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INVESTIGATION INTO THE ~MPACTOF CHROMIUM
CONTAMINATION IN THE SOilS AND
GIROUNDWATER UNDERlY~NG A MANUFACTUR~NG
PLANT ON A COASTAL AQU~FER
by
Mokete Makhutla
Submitted in fulfilment of the requirements for the degree of
Master of Sciel1lce
In the Faculty of Natural and Agricultural Sciences
Institute for Groundwater Studies
University of the Free State
Bloemfontein
South Africa
Supervisor: Dr P.D Vermeulen
February 2010
DECLARATION
28 February 2010
I, Mokete Saladiel Makhutla, declare that the thesis hereby submitted by me for the Master of Science
degree at the University of the Free State. Is my own independent work and has not previously been
submitted by me at another University/faculty. I further cede copyright of the thesis in favour of the
University of the Free State.
MOKETE SALADIEL MAKHUTLA
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing
plant on a coastal aquifer
Univef'$Ïtait V(Ml dis
Vrystaat
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ACKNOWLEDGEMENTS
I have to express my thanks to many people for their support and encouragement during the process of
my thesis. The acknowledgements given below are just a small choice of the whole.
My special thanks go to, Mr Doughlas Mbatha, Mr Peter Madanda, Mr William Ansell,
MS Dolly Mthethwa, MS Heidi Ali, MS Leanne Van Rooyen, MS Jackie Roux, Prof JG Van Tonder
and Or B.H Usher for their great ideas that made it possible for this thesis to be completed.
I thank Or P.D Vermeulen as a supervisor who guided me throughout the studying period. Without his
guidance and support it would not be possible to finish this thesis
At Jast but not least I thank my wife (Mrs Malit'sitso Makhutla) and my daughter (Miss Lineo
Makhutla) for their understanding and support during my absence.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing ii
plant on a coastal aquifer
ABSTRACT
The study area is located within the residential, commercial and industrial area, approximately 20km
to the south west of the Durban CBD, between a turf club site and the international airport of Durban.
Between 1945 and 1990, the site was used for the production of sodium dichromate (SDC), chromium
tanning salts, chromic acid and sodium sulphate. In 1991, the production of sodium dichromate (SDC)
was discontinued on the site, and manufacturing activities were limited to the production of chromium
tanning salts. These salts are used in the production of leather where they are essential in converting
perishable raw hides into durable leather.
In 2004, an investigation was initiated in the study area following the discovery of hexava lent
chromium [Cr(VI)] in groundwater. Cr(VI) was detected in groundwater samples taken from an open
pit excavated j ust outside the perimeter of the manufacturing plant site. It is considered that the actual
main source of the groundwater plume are suspected hot spots in the soil within aquifer 1 and 2. It is
most likely that the hot spots originated from SDC spills during former production and handling at
certain locations within the manufacturing plant site. It is reasonable to assume that the SDC entered
the groundwater from these production and handling locations and is still present in the soil voids
within aquifer 1 and 2. SDC liquid slowly dissolved the groundwater flowing around the hot spots and
would appear to be feeding the observed groundwater plume at present.
The specific aims of this research were to:
o Provide a literature overview of chromium contamination in the subsurface
o Establish the nature of geology and geohydrology underlying the manufacturing plant
o Quantify the levels and extent of chromium contamination in the soils and groundwater
underlying the manufacturing plant
• Identify the source of chromium contamination in the soils and groundwater underlying the
manufacturing plant and related potential pathways and exposure scenarios to the point of
exposure of the receptors
• Conduct a risk assessment for the soils and groundwater
Field activities associated with this investigation included the following:
• Hydrocensus survey
o Installation of new boreholes
• Borehole pumping tests
Investigation into the impact of chromium contamination in the soils and ground water underlying a manufacturing
plant on a coastal aquifer III
o Groundwater level monitoring
o Groundwater sampling
o Soil sampling at test pits
A hydrocensus survey conducted within a I km radius of the plant site revealed that there were no
private boreholes in or close to the affected area. The boreholes found were mainly industrial
boreholes in other industries around the manufacturing plant including the turf club site. These
boreholes were in the uncontaminated aquifer and most of them were either blocked or destroyed.
The investigations revealed that the fill underlying the site occurs from the surface to depths in the
range of approximately 0.4 metres to 2.1 metres below existing ground level. The fill generally
comprises brown to dark grey, silty sand to slightly clayey sand, and contains abundant gravel and
rubble in places. The fill overlies the harbour bed sediments, which generally occur in four
predominantly sandy aquifer horizons interlayered with clay layers of various composition and
thickness. The harbour bed sediments overlie sandstone of the Natal Group or sandy siltstones of the
St Lucia Formation at depths of between approximately 28 and 32 metres below existing ground level
on the manufacturing plant site. The weathered sandstone immediately below the harbour beds
generally comprises residual, highly weathered, orange brown, slightly clayey to silty sand. With
depth the sandstone typically becomes less weathered, grading into pinkish maroon sandstone bedrock
which extends to depths in excess of 100 metres below the site.
The hydraulic conductivity values of between 0.02 mid to 2.23 mid were estimated in various
aquifers underlying the manufacturing plant site.
The depth to the groundwater table ranged from 0.0 m to 3.1 m across the manufacturing plant site
area, as measured in the installed monitoring boreholes. The elevation of the groundwater table
ranged from 13.5 mMSL to 17.5 mMSL, with an inferred direction of groundwater flow towards the
east in aquifers I to 3.Within aquifer 4 and the Natal formation the groundwater flow was towards the
south east in principle corresponding to the general regional groundwater flow at depth from the hills
towards the sea.
The highest measured Cr(VI) concentrations in groundwater samples were found in aquifer I and
aquifer 2 underlying closed or dismantled production facilities on the manufacturing plant site where
sodium dichromate (SDC) liquid was produced or handled between 1945 and 1990. The highest
measured Cr(Vl) concentrations in soil samples taken at the manufacturing plant site coincide with
the above mentioned locations.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing
plant on a coastal aquifer
Based on the site investigations, a risk assessment for the soils and groundwater underlying the study
area was conducted using the RBCA approach in order to evaluate and assess the exposure scenarios.
The risk assessment focused on the following exposure pathways:
o Soil to human - The potential exposure of humans by ingestion, dermal contact or inhalation
of Cr(VI) or Crï lll) of contaminated soil.
o Soil to groundwater - The receptor or subject of protection is the groundwater with the point
of exposure at the ground water surface.
o Soil to plant - Concerns the potential uptake of Cr(VI) by the plants from contaminated
soil/groundwater.
• Groundwater - Is the migration of the Cr(VI) contamination within the ground water to any
receptor. It is addressed in this context as groundwater plume or plume only.
The measured concentrations both for Cr(III) and Cr(VI) in the soil samples taken on the
manufacturing plant site were always below the soil screening levels (SSL's) for ingestion and dermal
contact for commercial/industrial areas. Beneath certain areas of the plant site, the Cr(VI)
concentrations in the soil exceeded the SSL's for inhalation of fugitive particulates. These
contaminant values do not pose a health risk to workers on the plant site or on neighbouring industrial
sites, as in all instances the ground surface is covered by buildings and/or paved in concrete/asphalt.
The measured concentrations ofCr (VI) and Cr(IlI) in the soil samples were well below the SSL's for
ingestion and dermal contact in the neighbouring area. Hence neither of the concentrations ofCr(VI)
and Cr(III) found in the soils of the neighbouring area pose risk to humans.
Based on the results of the risk assessment for the exposure scenario soil to groundwater, it is evident
that on the manufacturing plant site outside the groundwater plume area, the Cr(VI) concentrations in
the soils were below the screening levels. In the vicinity of the 'hot spots' (active sources) the Cr(VI)
concentrations were above the screening levels. Therefore these contaminated soil areas have an
impact on the groundwater plume. In the residential area and turf club site, the measured Cr(VI)
concentrations in the soil samples outside the plume area and within the plume were all below the
screening levels. Hence the migration ofCr(VI) from the soil to the groundwater in the neighbouring
area is of no concern and does not pose a risk.
Numerous studies and scientific papers have indicated that the soluble Cr(VI) is not taken up easily by
plants. If taken up by plants or in general by living tissue it is rapidly converted to Cr(III). Cr(III) in
plants does not pose any risk to human health since it is an important component of a balanced human
diet. Hence the exposure scenario soil to plant to human does not pose a risk.
Investigation into the impact of chromium contamination in the soils and ground water underlying a manufacturing v
plant on a coastal aquifer
The measured concentrations for Cr(VI) in the groundwater samples taken in the plume area exceeded
all risk based screening levels for drinking water, irrigation and livestock, the contaminated
groundwater is clearly not suitable for drinking, irrigation and livestock, as exposure to large
quantities of the contamination could lead to serious health effects. The contaminated ground water
starts approximately I to 2 meters below the ground surface, provided a person does not come into
direct contact with the contaminated groundwater through drinking or skin contact, there would be no
risk of adverse health effects to the person.
Remediation of soil and ground water contamination at the manufacturing plant site is not expected to
be a simple matter that is likely to be achieved over a short period. Therefore, it has been important to
establish the risks that have to be dealt with, and to set targets for remediation that will be realistic to
achieve over time. In response to regulatory obligations, the risk assessment has been used as a basis
to set short-term, medium-term, and long-term targets for cleanup. The assessment has also set
preliminary remediation target concentrations for chromium contamination in the soils and
groundwater on the site.
Investigation into the impact of chromium contamination in the soils and ground water underlying a manufacturing vi
plant on a coastal aquifer
TABLE OF CONTENTS
CHAPTER 1 INTRODUCTION 1
1.1 Background .•......................•....•...........................•..........•......•............................................ 1
1.2 Objectives of the study .....•.................•.......••.................•............•...••.................................. 3
1.3 Methodology ..................................•...........•..............•.....•................................................... 3
CJHJ:APTER2 SITE D!ESCRIPTION ..........................•...........................................•..... 5
2.1 location ••..•...•......•........................•.....................•..........••.....•............................•.....•....•...... 5
2.2 Surrounding land use .......•.••........•....•......•.........•..........•...••.••.......................•........••........... 6
2.3 layout .................................•.............•..••..................•......••.....•..•...••...•..•....••...............•....... 7
2.4 Site history ........••..•................•.••........•...•...••.........••..•..••.........•...•...•..•....••........•..•.........•... 8
2.4.1 General 8
2.4.2 Previous operation 9
2.4.3 Current operation 9
2.5 Topography ........•..•.•.••......•..••.....•.••.......••.•..•....•.........••..••.....••..•..••...•........•....•..•....•.••..... 10
2.6 Climatic conditions 11
2.7 Surface run-off 13
2.8 Regional geology ....••.............••.......•...........•••.........•..........•................•....•....................•... 13
2.8.1 Introduction 13
2.8.2 St lucia formation 15
2.8.3 Bluff sandstone and Berea formations 15
2.8.4 Harbour beds 17
CHAPTER 3 CHROMIUM IN THE ENVIRONMENT:
LITERATURJE STUDY 18
3.1 Occurrence ............•••................••..........................•..•..•..............•.............••........•.••........... 18
3.2 Chromium chemistry ......•..................••..•..•..•....•....•........••............••..••.••................•..•..•..•• 18
3.2.1 Aqueous chemistry and pH effect 19
3.2.2 Reactions and mechanisms in aquifer systems 21
3.2.2.1 Precipitation 23
3.2.2.2 Adsorption 24
3.2.2.3 Reductionandfixation 25
3.3 Toxicity .....•..•...•..••........•....•..••.......••..••.......•..........•........•..•..••..••.....••..•.••....................•.•... 27
3.3.1 Human health 27
3.3.2 Ecological impacts 30
3.4 Site characterization requirements ..•..•••...•..••.......•...•..••.••................•....•..•..••....•............. 31
3.5 Chromium treatment and remediation approaches 32
3.5.1 Introduction 32
3.5.2 Groundwater extraction and treatment method 33
3.5.3 In situ technologies 36
Investigation into the impact of chromium contamination in the soils and ground water underlying a manufacturing
plant on a coastal aquifer vii
CHAPTER 4 FIELDWORK AND DISCUSSION OF RESULTS 37
4.1 Hydrocensus 37
4.2 Borehole installations 39
4.2.1 Introduction 39
4.2.2 Hand auger drilling 41
4.2.3 Rotary washbore drilling 42
4.3 Materials testing of soil samples 47
4.3.1 Hydraulic conductivity estimation based on grain size analysis .47
4.3.2 Hydraulic conductivity estimation based on laboratory tests 50
4.4 Borehole pumping tests 51
4.5 Groundwater level monitoring SS
4.6 Groundwater sampling 66
4.7 Soil sampling 72
CHAPTER 5 CONCEPTUAL SITE MODEL ............................................•.............. 78
5.1 Introduction 78
5.2 Sources of contamination 78
5.2.1 Primary sources 78
5.2.2 Secondary sources 79
5.3 Potential transport mechanisms 80
5.4 Exposure pathways 80
5.4.1 Air 80
5.4.2 Surface runoff 81
5.4.3 Soil 81
5.4.3.1 Hydraulic conductivity 81
5.4.4 Groundwater 83
5.4.4.1 Groundwater recharge 83
5.4.4.2 Groundwater levels 84
5.4.4.3 Groundwater flow directions 85
5.4.4.4 Seepage velocity 86
5.4.4.5 Retardation factors 87
5.4.5 Potential receptors and complete pathways 89
CHAPTER 6 RISK ASSESSMENT 9.1
6.1 Risk Based Corrective Action 91
6.1.1 Overview of RiskBasedCorrective Action 91
6.1.2 Hazard characterization and response under RBCA 93
6.1.3 RBCAsite classification 94
6.1.4 Tiered evaluation of Risk-Basedstandards 94
6.1.4.1 Tier 1:Generic Screening-Level Corrective Action Goal 95
6.1.4.2 Tier 2: Site-Specific Corrective Action Goals 95
6.1.4.3 Tier 3:Site-Specific Corrective Goals 96
6.2 Tier 1 evaluation 97
6.2.1 Introduction 97
6.2.2 Soil to human 97
6.2.3 Soil to groundwater 102
6.2.4 Soil to plant 105
6.2.5 Groundwater plume 105
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing viii
plant on a coastal aquifer
6.2.5.1 Excavation works 107
6.2.5.2 Graundwater extraction from shallow boreholes 108
6.2.5.3 Groundwater extraction from deep boreholes 108
CHAPTER 7 CONCLUSIONS AND RECOMMENDATIONS I09
7.1 Conclusions 109
7.2 Recommendations 114
CHAPTER 8 REFERENCES 117
APPENDICES 120
Investigation into the impact of chromium contamination in the soils and ground water underlying a manufacturing ix
plant on a coastal aquifer
LIST OF FIGURES
Figure 2.1: Locality of the site 5
Figure 2.2: Locality plan and land zoning 6
Figure 2.3: Layout of the site 8
Figure 2.4: Old production facilities 9
Figure 2.5: Manufacturing process of chromium tanning salts 10
Figure 2.6: General topography of the site 11
Figure 2.7: Average monthly temperatures for Durban 12
Figure 2.8: Average monthly rainfall for Durban 12
Figure 2.9: Geological map ofthe province of Kwazulu - Natal. 14
Figure 3.1: Eh-pH diagram for chromium 20
Figure 3.2: The chromium cyele in the environment 22
Figure 3.3: Chromium reduction and fixation 26
Figure 3.4: Concentration versus pumping duration showing tailing and rebound effect 33
Figure 3.5: Conceptual geochemical model of zones in a contaminant plume 35
Figure 4.1: Boreholes found during hydrocensus survey 39
Figure 4.2: Borehole locations on the manufacturing plant site and neighbouring area .40
Figure 4.3: Hand auger hole with temporary casing 42
Figure 4.4: Rotary washbore drilling rig 44
Figure 4.5: Groundwater level monitoring using a dip meter 55
Figure 4.6: Groundwater levels in aquifer 1 boreholes 57
Figure 4.7: Groundwater levels in aquifer 2 bore holes 57
Figure 4.8: Groundwater levels in aquifer 3 bore holes 58
Figure 4.9: Groundwater levels in aquifer 4 boreholes 58
Figure 4.10: Groundwater levels in Natal Group aquifer boreholes 59
Figure 4.11: Correlation between topography and groundwater levels in aquifer 1.. 60
Figure 4.12: Groundwater levels and flow directions in aquifer 1 61
Figure 4.13: Groundwater levels and flow directions in aquifer 2 62
Figure 4.14: Groundwater levels and flow directions in aquifer 3 63
Figure 4.15: Groundwater levels and flow directions within aquifer 4 64
Figure 4.16: Groundwater levels and flow directions within sandstone aquifer 65
Figure 4.17: Groundwater sampling using peristaltic pump and flow through cell 66
Figure 4.18: Maximum Cr(VI) concentrations within aquifer 1 68
Figure 4.19: Maximum Cr(VI) concentrations within aquifer 2 69
Figure 4.20: Maximum Cr(VI) concentrations within aquifer 3 70
Figure 4.21: Maximum Cr(VI) concentrations within aquifer 4 71
Figure 4.22: Soil sampling locations on the manufacturing plant site and neighbouring area 72
Figure 4.23: Test pit excavated for shallow soil sampling 73
Figure 4.24: Cr(lIl) concentrations in the soils at the depth of 0.3m 74
Figure 4.25: Cr(lIl) concentrations in the soils at the depth 0.6 m 75
Figure 4.26: Cr(VI) concentrations in the soils at the depth of 0.3m 76
Figure 4.27: Cr(VI) concentrations in the soils at the depth of 0.6m 77
Figure 5.1: Suspected hot spot locations based on observed Cr(VI) concentrations in
aquifer 1 and 2 79
Figure 5.2: Temperatures and rainfall in Durban 84
Figure 5.3: Sources, pathways, exposure scenarios and receptors of concern at the
manufacturing plant site 90
Figure 6.1: ASTM risk based corrective action flowchart 92
Figure 6.2: Maximum Cr(VI) concentrations in the top soil on the manufacturing plant 99
Figure 6.3: Maximum Cr(lIl) concentrations in the top soil on the manufacturing plant l00
Investigation into the impact of chromium contamination in the soils and ground water underlying a manufacturing x
plant on a coastal aquifer
Figure 6.4: Maximum Cr(VI) concentrations in the top soil off the manufacturing plant 101
Figure 6.5: Maximum Cr(lIl) concentrations in the top soil off the manufacturing plant 102
Figure 6.6: Maximum Cr(VI) concentrations in the top soil on the manufacturing plant 104
Figure 6.7: Projected extent of plume 107
Investigation into the impact of chromium contamination in the soils and ground water underlying a manufacturing XI
plant on a coastal aquifer
LIST OF TABLES
Table 2.1: Layout of the plant site 7
Table 2.2: Summary of the geology ofthe South Durban BasinArea 13
Table 3.1: CECsfor soils 24
Table 4.1: Summary of hydrocensus results 38
Table 4.2: Summary of boreholes installed during this study 40
Table 4.3: Summary of geology underlying the manufacturing plant and neighbouring area .45
Table 4.4: Summary of particle size distribution analysis .49
Table 4.5: Hydraulic conductivities estimated from grain size analysis using empirical
formulae 49
Table 4.6: Hydraulic conductivity of clayey soils based on laboratory tests 51
Table 4.7: Boreholes selected for pumping tests 51
Table 4.8: Summary of results of analysis of borehole pump tests 53
Table 4.9: Summary of estimated hydraulic conductivities for various aquifers underlying the
Manufacturing plant 54
Table 4.10: Summary of measured groundwater levels in the boreholes 56
Table 5.1: Summary of estimated hydraulic conductivities for aquifers underlying the
Manufacturing plant 82
Table 5.2: Summary of measured groundwater levels in the boreholes 84
Table 5.3: Summary of estimated seepage velocities for aquifers underlying the
Manufacturing plant 86
Table 5.4: Estimated retardation factors for Cr(VI) 88
Table 6.1: RBCAsite classification and response actions 94
Table 6.2: Exposure pathways and scenarios identified by CSM 97
Table 6.3: USEPAgeneric soil screening levels 98
Table 6.4: USEPAgeneric soil screening levels for migration to groundwater 104
Table 6.5: USEPArisk based screening levels for groundwater 105
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing xii
plant on a coastal aquifer
LIST OF ACRONYMS
AEC Anion Exchange Capacity
ASTM American Society for Testing Materials
Cr(IIl) Trivalent chromium (reduced form)
Cr(VI) Hexavalent chromium (Oxidized form)
CEC Cation Exchange Model
CCA Copper Chromium Arsenate
CBD Central Business District
DOC Dissolved Organic Carbon
OAF Dilution Attenuation Factor
DWEA Department of Water and Environmental Affairs
ET Department of Environment and Tourism
MSL Mean Sea Level
mbgl metres below ground level
m metres
MCL Maximum Contaminant Level
NTC National Toxicology Program
N/A Not Available
PRB Permeable Reactive Barrier
POE Point of Exposure
RBCA Risk Based Corrective Action
RBSL Risk Based Screening Level
RME Reasonable Maximum Exposure
SDBA South Durban Basin Area
SPT Standard Penetration Test
SSTL Site Specific Target Level
SSL Soil Screening Level
SL Screening Level
SDC Sodium Dichromate
TOC Total Organic Carbon
USEPA : United States Environmental Protection Agency
Investigation into the impact of chromium contamination in the soils and ground water underlying a manufacturing xiii
plant on a coastal aquifer
CHAPTER 1. INTRODUCTION
1.1 Background
Chromium is an important industrial metal used in diverse processes, including ore refining,
production of steel and alloys, pigment manufacture, plating metal, corrosion inhibition, leather
tanning, wood preservation, and combustion of coal and oil ( Adriano 2001; Papp 2001). At many
industrial and waste disposal locations, chromium has been released to the environment via
leakage and poor storage during manufacturing or improper disposal practices (Palmer and
Wittbrodt 1991; Calder 1988).
Fortunately, releases represent a very small fraction oftotal use and improvements of the
infrastructure have dramatically reduced the potential for future releases. Nevertheless,
a result of the utilization of chromium compounds is a legacy of soil and groundwater impacted
by chromium. Over the last 30 years recognition of the need for better environmental stewardship
has driven rapid evolution of science and technology associated with managing releases of
chromium compounds.
In the environment, chromium is commonly found in two most stable oxidation states as trivalent
chromium [Cr(IlI)] and hexavalent chromium [Cr(VI)], each characterized by distinctly different
chemical properties, bioavailability, and toxicity. Trivalent chromium is an essential element for
living beings, has relatively low toxicity, immobile under moderately alkaline to slightly acidic
conditions, and strongly partitioned into the solid phases, while hexavalent chromium is very
toxic, carcinogenic, and mutagenic to both animals and humans and may cause liver and kidney
damage and internal respiratory problems (Doisy et al. 1976; Yassi & Nieboer 1988; USDH
1991; Fendorf 1995). It is also very soluble, mobile, and moves at a rate essentially the same as
the groundwater (Palmer and Puis, 1994). Industrial applications most commonly use chromium
in the Cr(VI) form, which can introduce high concentrations of oxidized chromium (chromate)
into the environment.
The study area is located within the residential, commercial and industrial area, approximately
20km to the south west of the Durban CHD, between a turf club site and the international airport
of Durban. Between 1945 and 1990, the site was used for the production of sodium dichromate
lnvestigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 1
plant on a coastal aquifer
(SDC), chromium tanning salts, chromic acid and sodium sulphate. In 1991, the production of
sodium dichromate (SDC) was discontinued on the site, and manufacturing activities were limited
to the production of chromium tanning salts. These salts are used in the production of leather
where they are essential in converting perishable raw hides into durable leather. In 2004, an
investigation was initiated in the study area following the discovery of Cr(VT) in groundwater.
Cr(Vl) was detected in groundwater samples taken from an open pit excavated just outside the
perimeter of the manufacturing plant site. It is considered that the actual main source of the
groundwater plume are suspected hot spots in the soil within aquifer 1 and 2. It is most likely that
the hot spots originated from SDC spills during former production and handling at certain
locations within the manufacturing plant site. It is reasonable to assume that the SDC entered the
groundwater from these production and handling locations and is still present in the soil voids
within aquifer 1 and 2. SDC liquid slowly dissolved the groundwater flowing around the hot
spots and would appear to be feeding the observed groundwater plume at present.
Currently, most of the manufacturing plant site is covered in concrete or asphalt. However, the
possibility that workers could come in contact with the impacted subsurface soils on the plant site
at non-sealed surfaces cannot be ruled out completely. That scenario could cause a risk of
inhalation of dust particles containing chromium or ingestion of chromium contaminated soils
with concurrent skin contact. The residential stands in the area are small, mostly built up and
exposed areas are either concreted or tiled. However, the possibility that the general public could
come in contact with the impacted subsurface soils in the residential area at non-sealed surfaces
cannot be ruled out completely. That scenario could cause a risk of inhalation of dust particles
containing chromium or ingestion of chromium contaminated soils with concurrent skin contact.
The contaminated groundwater originating from the plant site could migrate into the residential
area and downstream of the plant site, thus posing immediate danger or acute health risk to the
population living in the residential area and downstream of the plant site. The movement of
groundwater and dispersion within the aquifer spreads the contaminant over a wider area, which
can then intersect with groundwater wells, making the water supplies unsafe. The use of
groundwater for irrigation purposes and drinking would create the possibility that humans come
into contact with Cr(VI)-contaminated groundwater. The most likely exposure route would be
dermal contact and ingestion. Any excavations and below ground level construction within the
plume area would potentially expose workers and members of the public to dermal contact with
the contaminated groundwater.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 2
plant on a coastal aquifer
Due to its adverse health effects, Cr(VI) poses a serious health risk to human health and that of
the environment. Hence, Cr(VI) contamination of the soils and groundwater is considered a major
environmental concern. This thesis aimed to investigate the processes leading to the scenario
outline above.
1.2 Objectives of the study
• To provide a literature overview of chromium contamination in the subsurface
o To establish the nature of geology and geohydrology underlying the manufacturing plant.
e To quantify the level and extent of chromium contamination in the soils and groundwater
underlying the manufacturing plant.
\!) To identify the source of chromium contamination in the soils and groundwater
underlying the manufacturing plant and related potential pathways and exposure scenarios
to the point of exposure of the receptors.
• To conduct a risk assessment for the soils and groundwater
1.3 Methodology
This project aimed to investigate the risk of chromium contamination in the soils and
groundwater underlying the manufacturing plant. A hydrocensus survey was conducted in a 1 km
radius of the plant site in order to establish if any groundwater extraction boreholes or wells
occurred in the area, and to identify the usage of the groundwater extracted from such sources.
Several new boreholes were drilled on the manufacturing plant site and neighbouring area. The
boreholes were installed to establish the subsoil conditions and to facilitate the monitoring and
sampling of the groundwater in the various aquifers underlying the study area. Certain aquifer
parameters needed to be investigated by carrying out materials testing of soil samples, laboratory
permeability tests and conducting pump tests.
The groundwater was accessed in order to study the geohydrology of the aquifers underlying the
manufacturing plant and surrounding area. The groundwater levels needed to be measured over a
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing
plant on a coastal aquifer
period of time in order to understand the processes taking place within the aquifers underlying the
study area.
Chemical data was collected in order to quantity the levels and extent of chromium contamination
in the soils and groundwater underlying the manufacturing plant and neighbouring area, and to
gain a full understanding of the hydrochemistry.
Based on the results of site investigations, a risk assessment conceptual model was developed in
order to identity the sources and related potential pathways and exposure scenarios to the point of
exposure of the receptors. A risk assessment for the soils and groundwater underlying the study
area was also conducted in order to evaluate and assess the exposure scenarios.
The methodology steps are listed as follows:
• Literature and background information study
o Hydrocensus survey
• Installation of new boreholes
• Materials testing of soil samples
• Borehole pumping tests
• Groundwater level monitoring
• Groundwater sampling
• Soil sampling at test pits
o Development of risk conceptual site model
• Risk assessment
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 4
plant on a coastal aquifer
CHAPTER 2. SITE DESCRIPTION
2.1 Location
The manufacturing plant is located within the residential, commercial and industrial area,
approximately 20km to the south west of the Durban CBD, between a turf club site and the
international airport of Durban, as shown in Figure 2.1.
Figure 2.1: Locality of the site (not to scale).
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 5
plant on a coastal aquifer
2.2 Surrounding land use
In terms of urban planning the manufacturing plant is zoned noxious industrial, and the
surrounding area is zoned special residential, educational, private open space, institutional,
worship, special shopping and general industrial as shown in Figure 2.2.
TURF CLUB
SITE
Figure 2.2: Locality plan and land zoning,
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 6
plant on a coastal aquifer
2.3 Layout
The site is roughly rhomboid in shape and covers an area of approximately 3.2 hectares. It is
bounded on the north west and north east by a railway reserve. The south eastern periphery of the
site is separated from the residential area by a municipal road, with an industrial site for lIIovo
sugar located immediately on the south western boundary of the site.
The site is occupied by a chromium tanning salts plant, laboratory, workshops, technical stores
and administration offices, as detailed in Table 2.1 below. The plant site and surrounding area is
served by paved roads and a municipal sewer and stormwater reticulation system. The layout of
the plant site is shown in Figure 2.3.
Table 2.1: Layout ofthe plant site
BuildinglFacility Occupied area Location within the site
(m2)
Major buildin2S
Administration offices 200 Southeastern part
Laboratory 120 Southwestern part
Raw material storage 375 Eastern part
Raw material storage tanks 75 Southern part
Adsorption plant 125 Southtern part
Chromium tanning salts plant 2436 Western part
(Mixing plant)
Bagging, pelletising and 400 Western part
shrink wrapping warehouse
Finished goods storage 3168 Central part
Container loading bay 150 Eastern part
Other buildings and facilities
Workshop and technical stores 1125 Southeastern part
Guardhouse 16 Southeastern part
Canteen 150 Southern part
Carport 100 Southeastern part
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 7
plant on a coastal aquifer
Figure 2.3: Layout of the site.
2.4 Site history
2.4.1 General
The history of the site and the manufacturing activities are summarised below.
• Between 1945 and 1968, the site was used for the production of sodium dichromate
(SDC), chromium tanning salts, chromic acid and sodium sulphate.
• Between 1985 and 1991, substantial improvements were implemented to address the
storm water drainage pathways. This included paving the process areas, lining the
underground municipal stormwater pipe through the site.
• In 1991, the production of sodium dichromate (SDC) was discontinued on the site, and
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 8
plant on a coastal aquifer
manufacturing activities were limited to the production of chromium tanning salts.
• In 2004, an investigation was initiated in the study area following the detection of
hexavalent chromium [Cr(VI)] in groundwater, in an open pit excavation just outside the
perimeter of the manufacturing plant site.
2.4.2 Previous operation
Prior to 1991, Sodium Dichromate (SDC) was produced at the site from mono chromate liquor by
acidifying it with sulphuric acid. After acidification the sulphate precipitate was centrifuged off
and sold. The liquid dichromate was evaporated and centrifuged to a moist crystal state which
was further dried before packing into containers. Figure 2.4 below shows the old production
facilities.
A02 SDC liquor offloading
A 14 Sulphur burner/absorption plant
AI5 SDC dissolving tank, water tank
A 17 SDC storage tanks
3 SDC Finished goods store
, ._._ ... _op_ .. _ .. _ ....... "- .. ..JI •• sea .... s •• c' 7 Main Plant
~2.1 .....m.?:: 6 13 Leaching plant14 SDC Plant
§ 15 Reject reduction plant17 Reject bins
1 Kiln
2 Crystal Dryer
.. 3 Quenching Plant
'\ 5 Chromic Acid Plant
Figure 2.4: Old Production facilities.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 9
plant on a coastal aquifer
2.4.3 Current operation
The manufacturing plant produces chromium tanning salts. These salts are used in the production
of leather where they are essential in converting perishable raw hides into durable leather.
The plant currently produces, as its main product, a basic chromium sulphate called Chromosal B
and two technically advanced products called Chromosal BF and Baychrom A. These products
are in powder form and are supplied in paper bags, plastic drums or big bags.
Chromium tanning salt is produced by reacting sodium dichromate with sulphur dioxide on a
continuous basis as shown in Figure 2.5 below. The resulting chromium tanning salt liquid is
spray dried to yield Chromosal B powder which is conveyed to storage hoppers in the bagging
plant. The sodium dichromate is imported to the plant site in liquid form. Sulphur dioxide is
produced by heating liquid sulphur. The Baychrom product is produced by blending chromium
tanning salts and various additives such as dolomite, sodium formate and sodium bicarbonate in
order to achieve specific properties. The manufacture and blending takes place in a modern
computer controlled mixing plant and a state of the art multi purpose bagging plant.
·SOCliquor =Chrornosal S ·Chromosal S
·Sulphur =Chromosal SF ·Chromosal SF
-Dolornlte ·SaychromA ·SaychromA
·Sodium formiate
=Sodium bicarbonate
=Sodaash
Figure 2.5: Manufacturing process of chromium tanning salts.
2.5 Topography
The manufacturing plant site is located on a gentle southeast facing slope, which generally grades
towards the municipal road site boundary on the east. The elevation of the site varies between
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 10
plant on a coastal aquifer
approximately 17.5 m above MSL in the western corner to approximately l3.5 m above MSL in
the eastern corner, as shown in Figure 2.6.
-4050 -4000 -3950 -3900 -3850 -3800 -3750 -3700 -3650 -3550 -3500
Figure 2.6: General topography of the site.
2.6 Climatic conditions
Durban's climate is characterised by warm humid summers (October to March) during which the
region receives most of it's precipitation. Winters (April to September) are cool and relatively
dry. Average monthly temperatures for the warmest month is 24.6°C (December) and for the
coolest month it is 16.6°C (July). Average annual rainfall is approximately 1000mm.
Investigation into the impact of chromium contamination in the soils and ground water underlying a manufacturing 11
plant on a coastal aquifer
Figures 2.7 and 2.8 below illustrate the average temperature and rainfall records for Durban for
the period 2004 to 2007.
• 2005 • 2006 • 2007
25
20
~
a:!!
.:.:.! 15
Q.
.E.....
10
Figure 2.7: Average Monthly Temperatures for Durban - (2005 to 2007) .
300 • 2005 .2006 .2007
250
200
Ë
!.
=150
"Ë
to
Ill<
100
so
o
}.>o Feb Mar Apr May
Figure 2.8: Average Monthly RainfaU for Durban - (2004 to 2007).
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 12
plant on a coastal aquifer
2.7 Surface run-off
The majority of the manufacturing plant site is currently paved in concrete or asphalt, and all
surface runoff is collected in surface drains before being discharged into the municipal
stormwater reticulation system. The run-off that is collected in surface drains from the production
area of the site is tested prior to being discharged to the municipal stormwater system. Where the
test results exceed the discharge criteria, the water is pumped into holding tanks and used as
process water in the plant.
2.8 Regional geology
2.8.1 Introduction
Regionally, the study area is located on the South Durban Basin Area (SDBA) and is underlain by
recent alluvial soils and Quaternary sediments (Harbour Beds) flanked on both sides by aeolian
sands of the Berea Formation. These sediments overlie Cretaceous bedrock of the St. Lucia
Formation. The Cretaceous bedrock is, in turn, underlain by Sandstone of the Natal Formation
and Tillite of the Dwyka Formation. The regional geology of the site is shown in Figures 2.9, and
the stratigraphy of the SDBA is summarised in Table 2.2 below.
Table 2.2: Summary of geology in the South Durban Basin Area (Brink, 1986)
Age Thickness
Formation Name Description
Mio.a (m)
Recent Alluvial sediments Brown clayey sand
Harbour Beds Sand with c~_~ 0-60
Quartenary o 1.5 Berea Sandy clay 0-100
Bluff Sandstone Calcarenite 0-200
Cretaceous -80 St. Lucia Silty sandstone 0-60
Ordovician >100 Natal Sandstone >100
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 13
plant on a coastal aquifer
T
Figure 2.9: Geological Map of the province of KwaZulu-Natal.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 14
plant on a coastal aquifer
2.8.2 St. Lucia formation
During the Cretaceous period approximately 80 million years ago, which followed the break up
of Gondwanaland, this part of the KwaZulu Natal coastline was inundated by the sea, with a
paleo-shoreline formed along the base of the Isipingo hills to the west. During this period of
marine transgression, a thick deposit of silty fine sand was deposited in a marine environment on
the drowned eroded bedrock surface. The bedrock surface comprised sandstone of the Natal
Formation, tillite of the Dwyka Formation, and shales of the Ecca Group. The Dwyka Formation
and Ecca Group forming part of the Karoo Sequence. The silty sands subsequently consolidated
to form the very soft to soft rock, silty sandstone of Cretaceous Age. The Cretaceous bedrock
occurs beneath the area at depths of between approximately 35 and 55 metres below existing
ground level. These sediments are termed the St. Lucia Formation. As such the St. Lucia
Formation rests unconformably on a very well-planed, inclined erosion surface on the underlying
much faulted bedrock of the Natal Group and Karoo Sequence. The Cretaceous sediments form a
wedge which thickens markedly in a seaward direction, with a corresponding decline in the
elevation of the underlying bedrock surface. Formation thicknesses increase from zero at the sub-
outcrop line along the toe of the Berea Ridge to some 3000m about 50km offshore. This stratum
is weakly bedded and jointed, dipping a few degrees seaward, and shows no signs of disturbance
since their deposition. Both faults and erosion of the underlying bedrock appear to pre-date the
Cretaceous sediments of the St. Lucia Formation.
2.8.3 Bluff sandstone and Berea formations
During the Tertiary and Quaternary Periods that followed the Cretaceous Period, rivers flowing
into the area deposited a mixture of boulders, gravel, sands and clays within the coastal estuarine
environment that existed. In addition, aeolian coastal dunes also formed during this time, with
the Bluff coastal dune thought to be a remnant of an early Quaternary dune. The Tertiary and
Quaternary Periods have been characterised by repeated cycles of marine transgressions and
regressions, with widely fluctuating sea levels. In particular, during the Quaternary Ice Ages,
abstraction of sea water into Polar ice caps reduced sea levels world wide by 100 metres or more.
As a result there was renewed erosion and down cutting by the rivers during periods of very low
sea level. Consequently, much of the previously deposited alluvial and aeolian deposits were
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 15
plant on a coastal aquifer
eroded and in some cases new channels were carved into the soft sandstone of the St. Lucia
Formation.
The Bluff Dune which encloses Durban harbour and the southern portions of Durban on their
seaward side is underlain by the Bluff Sandstone Formation. This formation comprises up to
about 200 metres of generally strongly bedded calcareous sandstone or calcarenite, mainly of
aeolian origin deposited during the Quaternary period. The formation extends to a depth of about
lOOmbelow present sea level and rests unconformably on the Cretaceous sediments of the St.
Lucia Formation.
The Bluff Sandstone Formation is the parent material of the Berea Formation, which was derived
from the former by a process of insitu weathering. Outcrops of the Bluff Sandstone are common
on the seaward side of the Bluff Dune along its entire length. The Berea Formation, or the Berea
Red sand as it is locally known, occupies the upper and inner portions of the Durban Bluff Dune
as well as the elevated Berea Ridges which parallel the coast. The Berea Ridge west of the
central city and harbour areas is part ofa compound coastal dune system of varying width which
extends along the entire southeastern coast of Africa.
The Berea Formation has a thickness of up to about lOOmand frequently overlies the bedrock
surface. A basal boulder bed of water-worn pebbles and boulders in a clayey sandy matrix is
often present where the Berea Formation overlies the bedrock surface. The Berea Formation has
a marked variation in its clay content (mainly kaolin), which may range from 2 to 50%. The clay
content being influenced particularly by the initial amount of weatherable feldspar. In general,
the older the material the higher its clay content and the more red in colour. Wind and water
redistribution of the surface material gives rise to a lighter coloured brown or grey sandy
superficial horizon overlying more reddish brown clayey sand subsoil. With increasing depth
into the dune cone, the material generally becomes progressively less weathered and thus less
clayey and lighter in colour.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 16
plant on a coastal aquifer
2.8.4 Harbour beds
As sea levels rose after the last ice age, the Harbour Beds were deposited within a lagoonal area
that existed between the Bluff Coastal dunes and hillsides of the Isipingo area to the west. Many
of the deep river channels were infilled initially with boulders and then with coarse sands and
gravels. As the river gradients lessened coarse sediments gave way to fine sands, silts and clays
deposited on the new still waters of the lagoon behind the windblown sands of the Bluff Dune.
As a result of the changing depositional environment, the Harbour Beds are extremely variable
both in depth and lateral distribution and comprise predominantly sands with layers and lenses of
clay. These sediments rest unconformably on various older strata, and underlie the Central
Business District (CBD) and Harbour areas of Durban and the low lying areas to the north and
south thereof. Sediment thicknesses are variable. Beneath the CBD the Harbour Beds are on
average about 30m thick. However, to the south and to the north of the CBD its thickness is in
excess of 60m.
Investigation into the impact of chromium contamination in the soils and groundwatcr underlying a manufacturing 17
plant on a coastal aquifer
CHAPTER 3. CHROMIUM IN THE ENVIRONMENT:
LITERATUTURE REVIEW
3.1 Occurrence
Chromium is an ubiquitous contaminant of soils and groundwater and is derived from both
natural and anthropogenic sources (Francoise & Alain 1991). It occurs in combination with other
elements as chromium salts, some of which are soluble in water. The pure metallic form does not
occur naturally. Chromium does not evaporate, but it can be present in air as particles.
Chromium is an important industrial metal used in diverse processes, including ore refining,
production of steel and alloys, pigment manufacture, plating metal, corrosion inhibition, leather
tanning, wood preservation, and combustion of coal and oil ( Adriano 2001; Papp 2001). At many
industrial and waste disposal locations, chromium has been released to the environment via
leakage and poor storage during manufacturing or improper disposal practices (Palmer and
Wittbrodt 1991; Calder 1988).
In the environment, chromium is commonly found in two most stable oxidation states as trivalent
chromium [Cr(lII)] and hexavalent chromium [Cr(VI)], each characterized by distinctly different
chemical properties, bioavailability, and toxicity. Cr(I1I) is an essential element for living beings,
has relatively low toxicity, immobile under moderately alkaline to slightly acidic conditions, and
strongly partitioned into the solid phases, while Cr(VI) is very toxic, carcinogenic, and mutagenic
to both animals and humans and may cause liver and kidney damage and internal respiratory
problems (Doisy et al. 1976; Yassi & Nieboer 1988; USDH 1991; Fendorf 1995). It is also very
soluble, mobile, and moves at a rate essentially the same as the groundwater (Palmer and Puis,
1994). Industrial applications most commonly use chromium in the Cr(VI) form, which can
introduce high concentrations of oxidized chromium (chromate) into the environment. Cr(VI)
does not always readily reduce to Cr(III) and can exist over an extended period of time.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 18
plant on a coastal aquifer
3.2 Chromium chemistry
The basic chemistry of chromium in the various oxidation states accounts for the behaviour of
this metal in the natural environment, and links this information to in situ technologies discussed
in the section 3.5.
3.2.1 Aqueous chemistry and pH effect
Chromium has a unique geochemical behaviour in natural water systems. Crfll'l) is the most
common form of naturally occurring chromium, but is largely immobile in the environment, with
natural waters having only traces of chromium unless the pH is extremely low. Under strong
oxidizing conditions, chromium is present in the Cr(VI) state and persists in an anionic form as
chromate. Natural chromate are rare. However, the use ofCr(Vl) in wood preserving CCA
solutions, metal plating facilities, paint manufacturing, leather tanning, and other industrial
applications has the potential to introduce high concentrations of oxidized chromium to the
environment (Rouse and Pyrih 1990; Palmer and Wittbrodt 1991).
Redox potential Eh-pH diagrams present equilibrium data and indicate the oxidation states and
chemical forms of the chemical substances which exist within specified Eh and pH ranges as
shown in Figure 3.1.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 19
plant on a coastal aquifer
1.2
oo ';exavalent ChromiumTrivolenl Chromium
1
0.8
0,6 -
+3
Cr
crC -2.'--" 4
G 0.4
.£: CrOH -1".2 Cr(OH) .-+2
lW
O.?
0
Cr(OH);
Cr(OHtcÏ
-0.4
·0.%
o 10 12 14
SI)Inee: Paltner ëllldWiUbrodL 1991 pH
Figure 3.1: Eh-pH diagram for chromium.
The data presented in Figure 3.1 above are derived from parameters representing typical aqueous
conditions. Although the diagram implies that the boundary separating one species from another
is distinct, the transformation is so clear cut. Concentration, pressure, temperature, and the
absence or presence of other aqueous ions can all affect which chromium species will exist. A
measure of cation must be exercised when using this diagram as site-specific conditions can
significantly alter actual Eh-pH boundaries. Palmer and Wittbrodt (1991) claim that chromium
exists in several oxidation states ranging from 0 to 6. Under reducing conditions, Cr(lII) is the
most thermodynamically stable oxidation state. However, Cr(VI) can remain stable for significant
periods of time.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 20
plant on a coastal aquifer
In soils and aquifer systems, the most prevalent forms are the trivalent and hexavalent oxidation
states.
Cr(H1) exists in wide Eh and pH ranges. Palmer and Wittbrodt (1991) have determined that the
following Cr(II1) species exist with respect to pH. Cr(IIl) predominates as ionic (i.e, Cr +3)at pH
values less than 3.0. At pH values above 3.5, hydrolysis of Cr(III) in a Cr(III)-water system yields
trivalent chromium hydroxyl species [CrOH+2, Cr(OH)/, Cr(OH)3o and Cr(OHk]' Cr(OH)3° is
the only solid species, existing as an amorphous precipitate. The existence of the Cr(OH)3o
species as the primary precipitated product in the process of reducing Cr(VI) to Cr(IlI) is
paramount to the viability of in situ treatment using reactive zone technology, such as microbial
bioreduction. Cr(IIJ) can form stable, soluble (and thus mobile), organic complexes with low to
moderate molecular weight organic acids (i.e., citric and fulvic acids) the significance of these is
that they allow Cr(IJI) to remain in solution at pH levels above which Cr(III) would be expected
to prescipitate (Bartlett and Kimbie 1976a ; James and Bartlett 1983a).
3.2.2 Reactions and mechanisms in aquifer systems
The chemistry of aqueous chromium in an aquifer is complicated, interactive between soil and
water, and cyclic in the reactions that occur as they relate to solid and dissolved phases and
various oxidation states present. The "Chromium Cycle" is presented in Figure 3.2 below.
Understanding this chemical process is important in the decision-making process in determining
which treatment technology (either singly or in combination) to use.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 21
plant on a coastal aquifer
Figure 3.2: The chromium cycle in the environment.
The two major oxidation states of chromium which occur in the environment are Cr(lII) and
Cr(VI). According to Bartlett (1991), the following conditions exist, Cr(VI) is the most oxidized,
mobile, reactive, and toxic chromium state. In general, under non-polluting conditions, only small
concentrations of Cr(VI) species exist [the result of oxidation of natural Cr(III)], with Cr(III)
species being the most prevalent forms. Most soils and sediments in partial equilibrium with
atmospheric oxygen contain the conditions needed in which oxidation and reduction can occur
simultaneously. Cr(IU) species may be oxidized to Cr(VI) by oxidizing compounds that exist in
the soil (i.e., manganese dioxide - Mn02), while at the same time Cr(VI) species may be reduced
to Cr(IH) by Mn02 in the presence of reduced manganese oxide (MnO) and organic acids from
soil organic matter (including humic acid, fulvic acid, and humin), soluble ferrous [Fe(II)], and
reduced sulphur compounds. Therefore, it is important to understand the geochemical
environment of any site where Cr(VI) is likely to occur.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 22
plant on a coastal aquifer
The success of geochemical fixation treatment techniques is based on forming insoluble non-
reactive chemical species. Precipitation and adsorption result in fixation or solid-phase formation
of Cr(lII), each depending on the physical and chemical conditions existing in the aquifer system.
3.2.2.1 Precipitation
Precipitation reactions can be further divided into three types, pure solids such as Cr(OH)3o
(amorphous precipitation), mixed solids or coprecipitates such as
CrxFel.x(OH )3, and high molecular weight organic acid complexes such as humic acid polymer
(Palmer and Wittbrodt 1991 and James and Bartlett 1983b). Pure solid Cr(IlI) hydroxide
precipitates result from changes in the Eh-pH parameters (Figure 3.1).
Chromium hydroxide solid solutions may precipitate as coprecipitates with other metals rather
than Cr(OH)3 ° . This is especially true if oxidized iron [Fe(n)] is present in the aquifer, it will
generate an amorphous hydroxide coprecipitate in the CrxFel_x(OH)3 form (Palmer and Wittbrodt
1991). This chemical reaction is particularly important due to the potential for Fe(H) to be
oxidized to the ferric state as previously discussed. Fe(Il) is the most common oxidation state of
dissolved iron in natural subsurface waters as well as aquifer minerals. Advantage is taken of this
chemical reaction when employing permeable reactive barrier (PRB) in situ treatment of
groundwater. Zero-valent iron (FeO)metal is used to reduce Cr(Vl) to Cr(III) and complex the
Cnlll) as a Fe(HI) hydroxide coprecipitate.
Insoluble organic acid complex precipitates with Cr(III) and soil humic acid polymers are
generally quite stable and present a barrier to Cr(HI) oxidation to Cr(VI). Cr(lIJ) is slightly bound
and immobilized by insoluble humic acid polymers.The name given to this complexation process
is chrome tanning because chromium has replaced aluminium in the tanning of leather. The
chrome tanning of soil organic matter limits the tendency for Crtlll) to become oxidized and for
the organic matter to be decomposed (Ross et aI., 1981).
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 23
plant on a coastal aquifer
3.2.2.2 Adsorption
Adsorption reactions generally consist of cation exchange capacity (CEC) mechanisms for Cr(l1l)
species and anion exchange capacity (AEC) mechanisms for Cr(Vl) species. Adsorption generally
involves cation exchange of Cr(III) as ct3 or hydroxy ionic species onto hydrated iron
manganese oxides located on the surface of clay soil particles. fn CEC mechanisms, an aquifer
mineral lattice or hydrated iron and manganese oxides located on the surfaces of fine-ingrained
soil particles adsorb cations. Competition with other similar ions is possible and may limit the
absorption of one particular species. Understanding CEC mechanisms is critical when considering
in situ treatment technologies, such as soil flushing/chromium extraction and electrokinetic
remediation. Generally, the lower the CEC of the soil, the better suited the soil for remediation by
these technologies. Table 3.1 presents the CECs for various soil classifications (Dragun, 1988).
The soil organic matter component of soil provides the greatest CEC, followed by the clay
minerals vermiculite, saponite and montmorillinite. Clay offers the greatest CEC of all the soil
types.
Table 3.1: CECs for soils - Components and types
CEC
c (meq/lOOe)
Soil clays
Chlorite 10-40
IIIite 10-40
Kaolinite 3-15
Montmorillonite 80-150
Oxides and Oxyhydroxides 2-6
Saponite 80-120
Vermiculite 100-150
Soil types
Soil Organic Matter >200
Sand 2-7
Sandy Loam 2-18
Loam 8-22
Silt Loam 9-27
Car port 4-32
Clay 5-60
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 24
plant on a coastal aquifer
In addition to soil cation exchange mechanisms for Cr(IU) species adsorption, soil anion
exchange is possible for adsorption of Cr(VI) anions [i.e., hydrochromate (HCr04-) and
chromate (Cr04-2)]. These species exchange with chloride (Cr), nitrate (N03), sulphate (SO/),
and phosphate (P04-3). Griffin et al. (1977) studied the effect of pH on the adsorption of Cr(Vl)
by the clay minerals kaolinite and montmorillonite, and found adsorption was highly pH
dependent; the adsorption of Cr(VI) decreased as pH increased, and the predominant Cr(VI)
species adsorbed was HCr04-. Bartlett and KimbIe (1976b) also found that while chromate is
tightly bound compared with anions such as cr or N03-, it can be released by reaction of the soil
with P04-3. The presence of orthophosphate prevented the adsorption ofCr(VI) anions,
presumably by competition for the adsorption sites. They concluded that the behaviour of Cr(VI)
remaining in soils is similar to that of orthophosphate, but unlike phosphate, Cr(VI) is quickly
reduced by soil organic matter, thus becoming immobilized. Cr(VI), they state, will remain
mobile only ifits concentration exceeds both the adsorbing and the reducing capacities of the soil.
Sulfate adsorption on kaolinite also varied with pH, although not as strongly as for chromate.
Zachara et al. (1988) suggested that, although S04-2 and Cr04-2 compete for adsorption sites on
noncrystalline iron oxyhydroxde, S04-2 and Cr04-2 bind to different sites on kaolinite and, thus,
do not compete for the same site. Studies by Zachara et al. (1989) of the adsorption of chromate
on soils found the following:
• Chromate adsorption increased with decreasing pH.
o Soils that contained higher concentrations of aluminium and iron oxides showed greater
adsorption of Cr(VI).
• Chromate binding was depressed in the presence of dissolved S04-2 and inorganic carbon,
which compete for adsorption sites.
3.2.2.3 Reduction and fixation
In situ treatment methods for chromium-contaminated soil and ground water generally involve
the reduction of Cr(VI) to Cr(ITI) with subsequent fixation of Cr(IlI).
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 25
plant on a coastal aquifer
~&s).; CrjVl) Ramaill!;
In Environment
(AqF~ueII(. o)us] __ I
Nalurnl~' Mn(llI) Organic '-........t Sodium MotaSic-tJlfite Chemical
R~::Iuclion .<\r;(i'dAJmp!~70e~/71'" Reduction
Sc-.ll OI!J<lnrC M<ïtt~J'
Cr{lll)
Inorganic (i.e, iron) Co-ppt
ami Insoluble Humic Hydrolysis
Acid CorlJpla:t~B
'~i.ÏOl1 Exchange --.
on Fin e Grflined Soil
Adsorption
1=1XATION
Figure 3.3: Chromium reduction and fixation.
Figure 3.3 presents examples of natural and chemical-induced reduction ofCr(VI) to Cr(U1) and
the mechanisms of subsequent fixation of Cr(JII). The permanence of fixation must be evaluated
since Cr(IIl) [as low molecular weight organic acid complexes (i.e chromium citrate)] can
migrate to the surface and reoxidize to Cr(VI) in the presence of manganese dioxide. Manganese
dioxide (Mn02) forms naturally in the upper vadoze zone by reduced manganese oxide (MnO)
reacting with atmospheric oxygen. 8artlett (1991) states "the marvel of the chromium cycle in
soil is that oxidation and reduction can take place at the same time." This is an important
principle for the application of in situ technologies for the treatment (reduction) ofCr(VI) and
permanent fixation of Cr(III).
Figure 3.2 illustrates the apparent paradox of simultaneous oxidation and reduction of chromium.
As shown, Mn(IV) (as Mn02) oxidizes Cr(IJI) to Cr(VI). However, under normal dry soil
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 26
plant on a coastal aquifer
conditions, mobile Cr(UI) [i.e.,Ct3 or chromium citrate] will not oxidize to Cr(VI) in the
presence ofMn02. Mobile Cr(lII) will not oxidize to Cr(VI) in the presence of Mn02 unless the
soil is moist and the Mn02 surface present in the soil is fresh (i.e., amorphous rather than
crystalline form) (Bartlett, 1991). Additionally, Mn(lII)-organic acid complexes reduce Cr(IV) to
its trivalent form. Mn(III) is formed when Mn(II) reacts with Mn(IV) in the presence of organic
acids formed from soil organic matter (Bartiett, 1991). The cycle repeats itself as the Cr(III)
formed may be chelated by low molecular weight organic acid complexes (e.g., citric acid) and
thus, be mobile enough to migrate to the soil surface and consequently oxidize to Cr(VI).
Bartlett (1991) states that as long as all Cr(VI) has been reduced and all Cr(UI) is bound by
decay-resistant organic polymers, the chromium will remain inert and immobile, provided that
oxygen is excluded. In other words, sealing of a landfill on the bottom to prevent leaching of
chromium is unnecessary as long as the top is sealed.
3.3 Toxicity
3.3.1 Human health
Chromium, a metallic element, is naturally occurring in rocks and minerals, most usually in its
trivalent state, Cr(IIl). Cr(lIl) is an essential nutrient, albeit in trace quantities. The element has a
role in the metabolism of glucose, fat and protein, by making the action of the hormone, insulin,
more effective. Chromium also exists in valence states other than Cr(III), and one of these forms,
Cr(Vl), has been released to the environment as a result of industrial processes. Cr(VI) is also
known as hexavalent chromium, and the name may be abbreviated to Cr+6• There is wide
industrial use ofCr(VI) compounds, and a few examples of the industries that utilize them
include wood preservation; hard and soft chrome plating; pigment manufacture, the aerospace
industry; leather tanning, and the textile industry. Cr(VI) was formerly in wide use as a corrosion
inhibitor in wastewater systems and to prevent degradation of iron and steel pipe. Although
uecades have passed since its use as a corrosion inhibitor, it may still be found plated to treated
pipes.
Occupational exposure to Cr(VI) generally occurs by inhalation and by skin (dermal) contact.
However, when a substance is inhaled, a small amount is inevitably ingested. Workers may be
exposed by inhalation to fumes and mists containing Cr(VI) when hot cutting or welding stainless
steel, or other chromium-containing metal alloys. Portland cement contains CrCvI) as an
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 27
plant on a coastal aquifer
impurity, and workers may be exposed by inhaling cement dust. Workers in the electroplating
industry can be exposed to Cr(VI) by inhaling mists of electroplating solutions and by dermal
contact with them. The production of Cr(VI) pigments, their use in sprayed-on coatings by
aerospace industry, has exposed workers by skin contact and inhalation. The general public may
be exposed to Cr(VI) by drinking from the contaminated groundwater wells, inhaling mists from
cooling towers where water flows over treated timber, inhaling fugitive dusts from cement and
chromate producing plants, and inhaling emissions from motor vehicles, catalytic converters.
Particulate Cr(VI) may be inhaled, and deposited in the lungs, but the pattern of deposition in the
lungs is dependent on airflow patterns in the lungs. Some sites in the lung may preferentially
build up Cr(VI) to create areas of high concentration. Cr(VI) is absorbed into the cells of the lung
by facilitated diffusion through non-specific ion channels and is thence rapidly absorbed into the
bloodstream. The readily soluble chromates reach the bloodstream more rapidly than less soluble
compounds, but even Cr(VI) encapsulated in paint may be absorbed from the lung. Some inhaled
Cr(VI) is removed from the lungs by mucociliary clearance. Mucociliary clearance and
swallowing can move inhaled substances to the digestive tract. Ingested Cr(VI) is largely reduced
to insoluble Cr(III) in the gastrointestinal tract. However, animal studies show that a proportion of
ingested Cr(VI) is absorbed. Cr(VI) is absorbed through intact skin, easily crossing the epidermis
to the underlying layer, the dermis, and from the dermis into deeper tissues. Once absorbed,
Cr(VI) is distributed through the body via the bloodstream. Tissues retrieved from autopsies of
chromate workers indicate high Cr(VI) concentrations in the lungs, and higher than background
concentrations in liver, bladder, and bone. Cr(VI) is excreted in urine as low molecular weight
Cr(III) complexes, and to a lesser extent by biliary excretion into faeces.
The toxicity Cr(VI) has been investigated in laboratory animal studies, and results have been
reported from both short and long-term investigations. A recent National Toxicology Program
(NTP) study, reported January 2007, examined the mid-term toxicity ofCr(VI) to rats and mice.
The test animals were administered sodium dichromate in their drinking water for 3 months, and
this exposure resulted in focal ulceration, metaplasia, and hyperplasia of the glandular stomach on
both rats and mice. Evidence of histiocytic infiltration of the liver, duodenum, and pancreatic
lymph nodes was also observed. Microcytic, hypochromic anemia was noted in rats, and, to a
lesser extent, in mice. The development of anemia was considered a toxic response to the oral
ingestion of Cr(VI). Other studies have demonstrated that rats exposed to Cr(VI) by inhalation for
a period of3 months show an increase in lung and spleen weight and in macrophage activity.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 28
plant on a coastal aquifer
Long- term (chronic) animal studies have primarily focused on the potential ofCr(Vf) to cause
cancer. The results of a recent 2 year NTP study on the effects of Cr(VI) in drinking water in rats
and mice found clear evidence of carcinogenicity of sodium dichromate. Carcinogenic effects of
oral administration ofCr(VI) were seen in both rats and mice of both sexes. Squamous cell
papillomas, or squamous cell carcinomas were seen in the oral mucosa or tongue of rats. Mice in
the same investigation developed neoplasms, and adenomas or carcinomas of the duodenum,
jejunum, or ileum. Lung implantation ofCr(VI) in rats has shown a statistically significant
increase in squamous metaplasia, a condition that may progress to carcinoma of the lungs. Some
investigations, but not all, have found statistically significant increases in bronchial carcinoma
after intrabronchial instillation of Cr(VI) compounds. Subcutaneous, "site of injection," cancers
have been reported for Cr(VI) .
Two animal studies show Cr(VI) to be toxic to the developing embryo. Mice and rats exposed to
Cr(VI) in drinking water during gestation exhibited retarded fetal development, and embryo and
fetotoxic effects that included reductions in the number of foetuses and fetal weight and a higher
incidence of stillbirth and post-implantation loss. Both studies found significantly reduced bone
ossification. However, a multigenerational dietary study performed by NTP observed no
reproductive changes due to the toxicity of Cr(VI). There is no clear evidence that Cr(VI) is a
human reproductive toxicant following occupational exposure. The only studies that address this
issue are of poor quality and provide insufficient data to draw any conclusions about the
reproductive toxicity ofCr(VI) in man.
Both soluble and insoluble Cr(VI) are able to cause structural damage to DNA, leading to
genotoxicity. Cr(Vl) compounds, such as sodium dichromate, are mutagenic in Salmonella
typhimurium reverse mutation assays, and in Escherichia coli tests. Studies indicate that Cr(VI)
induced DNA damage may result in c1astogenesis, altered gene expression, and the inhibition of
chromium replication and transcription. The genotoxic action ofCr(VI) is probably responsible
for the induction of neoplastic change.
There are strong occupational health studies in chromate production workers from the USA, UK,
Germany, Japan, and Italy. Chromate production plants in the USA and UK have been repeatedly
studied for extended periods, one in Painsville, Ohio for 50 years. These studies evidence that
Cr(VI) is carcinogenic to workers, as they report an elevated lung cancer mortality that is related
to cumulative exposure, and length of employment. Occupational health studies also provide data
for the non-cancer effects of Cr(VI). Inhalation of Cr(VI) leads to ulceration of nasal tissues 10
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 29
plant on a coastal aquifer
nasal septum perforation. Cr(VI) is an airway sensitizer and can produce occupational asthma in
sensitized individuals, and in addition, can cause allergy contact and irritant contact dermatitis.
Skin ulcers, known as "chrome holes," can occur on exposed skin. These ulcers are persistent,
painful, and may result in deep penetration of tissues underlying the skin.
A study of villagers in China using Cr(VI)-contaminated well water (20 mg per liter) for domestic
purposes reported the following effects of oral exposure: vomiting, oral ulcers, abdominal pain,
indigestion, and diarrhea. Hematological effects such as leucocytosis and immature neutrophils
were also noted. Cr(VI) has been classified by the US EPA under the 1986 cancer guidelines as
Group A known human carcinogen by the inhalation route of exposure, and as Group D
carcinogenicity cannot be determined by the oral route of exposure. Under the interim 1996
cancer guidelines EPA classifies Cr(VI) as a "known human carcinogen by the inhalation route of
exposure." The report on carcinogens (II th Edition) states that, "chromium hexavalent (VI)
compounds are known to be human carcinogens".
3.3.2 Ecological impacts
Chromium is an essential nutrient for human beings and chromium containing low molecular
weight peptides (chromodulin) have been identified in many mammalian species. However, it is
not known whether chromium is a dietary requirement for other terrestrial vertebrates. Although
chromium does bioaccumulate, it is not reported to undergo biomagnification in the food chain.
Many biotic and abiotic factors can modify the toxic effects of chromium in the environment. For
example, Cr(VI) is more toxic to freshwater biota in soft, slightly acidic water. Early life stages
are generally more sensitive to the effects of Cr(VI) than adults.
Cr(Vl), at a concentration of 10 parts per billion (ppb) reduced fecundity and survival of the
invertebrate Daphnia magna when the organisms were exposed to the metal for 32 days, but is
also associated with adverse impact to other invertebrates from widely differing taxa. Cr(VI) is
reported to be slightly to moderately toxic to aquatic polychaete and oligochaete worms in
median lethal concentration (LC50) studies. Some fish species are sensitive to Cr(VI), and
relatively low concentrations (1621 ppb) reduced the growth of young rainbow trout and Chinook
salmon during a 14 - 16 weeks exposure period. LC50 studies have determined that Cr(Vl) is not
acutely toxic, to slightly toxic to amphibians (Indian toad and skipping frog under test).
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 30
plant on a coastal aquifer
Very little information is available for the effects ofCr(VI) on terrestrial mammals and birds.
Laboratory animal studies have provided mammalian toxicity data. An egg injection study of the
effects ofCr(VI) on the developing domestic fowl resulted in deformities that included twisted
limbs, exencephaly, everted viscera, deformed beaks, and growth stunting. However, no effects
were seen in adult chickens fed Cr(VI) at 100 ppm in their diet for 32 days.
Plants can be adversely affected by Cr(VI). It reduces the growth and chlorophylls a and b
content of the small, floating aquatic fern Azolla caroliniana at concentrations of 1-2 ppm.
Reduced germination, a decrease in root length and dry weight, reduction in plant height, number
of flowers, leaf number, leaf area and biomass, and an up to 50% reduction in grain weight, with
increased seed deformity have all been reported in response to Cr(VJ).
3.4 Site characterization requirements
The remediation site should be characterized to determine how suitable it is for Crflll) fixation or
for other treatment application. Chemical characterization should include the following:
• Site characterization
e Groundwater
• Soil
Site characterization should include a determination oftotal organic carbon (TOC) and dissolved
organic carbon (DOC) in the groundwater and soil. Both tests will indicate not only the
availability of soluble organic ligands for Cr(nI) complexing, which provides a mobilization
vehicle for potential oxidation to Cr(VI), but also the availability of more complex organic matter
which has the potential for reduction ofCr(VI) to Cr(IlI). The particulate (or solid fraction) of
organic carbon in the aquifer can be determined by subtracting DOC from TOC. A total Cr(VI)
reducing capacity of the soil should be determined to measure the portion of organic matter in the
soil that is oxidizable by Cr(VI). The Cr(VI) not reduced is titrated with Fe(H). CEC should be
measured to determine if sites are available for Cr(III)-hydroxyl cation complexes to adsorb onto
the soil particles. Other tests that can be performed as needed are porosity, grain size, soil
moisture and total manganese.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 31
plant on a coastal aquifer
Both contaminated and treated groundwater should be analyzed for total chromium and Cr(VI);
Cr(lIl) is determined by subtracting the results of the Cr(VI) from the total chromium values. Eh
and pH should also be determined. Like the groundwater, both contaminated and treated aquifer
solids and unsaturated soil should be analyzed for total and Cr(VI). Additional tests should be
conducted for pH and the amount of dissolved Cr(lII) that is mobile (not fixed). Further, in order
to determine if, and how much of, the Cr(VI) was reduced, a mass balance should be performed.
Other soil tests that can be performed as needed are the standard chromium oxidation test; Cr(IIT)
oxidizable by excess Mn02; and oxidizability of inert Cr(III). The methods for these tests, along
with their rationale, are presented in Bartlett (1991). In addition to site chemistry, it is also
critically important for in situ technology implementation to understand the contaminant
distribution and geologic setting. This includes geologic structure, stratigraphy, and groundwater
hydrogeology. Complicated geology and low permeability zones will influence how a technology
is applied and its treatment effectiveness. Laboratory and pilot-scale tests can help to determine
the effectiveness of the treatment on the contaminated matrix prior to full-scale application of the
technology.
3.5 Chromium treatment and remediation approaches
3.5.1 Introduction
Groundwater extraction and treatment has traditionally been used to remediate chromium-
contaminated plumes. This method, while providing interception and hydraulic containment of
the plume, may require long-term application to meet Cr(VI) remediation goals and may not be
effective at remediating source-zone Cr(VI). Treatment approaches have been developed for
chromium-contaminated soil and groundwater treatment. A number of available in situ
technologies or treatment approaches use chemical reduction and fixation for chromium
remediation. These include geochemical fixation, permeable reactive barriers (PRBs), and
reactive zones. Other types of in situ treatment that are under development include enhanced
extraction, electrokinetics, biological processes that can be used with PRBs and reactive zones,
natural attenuation, and phytoremediation.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 32
plant on a coastal aquifer
3.5.2 Groundwater extraction and treatment method
Palmer and Wittbrodt (1991) discussed several remediation techniques for chromium-
contaminated sites. Applicable to many sites is a pump-and-treat method. The technology works
by extracting contaminated groundwater, usually over long time periods, and providing hydraulic
control (containment) of a contaminant plume. Initially, the concentration of the contaminant is
high in the affluent, but with continued pumping, the concentration decreases significantly. These
residual concentrations remain above the MCLs, and can persist for long periods of time, called
"tailing." This same phenomenon was observed by Stollenwerk and Grove (1985) in their
laboratory and batch column experiments.
PLlmpingOn Pumping Off
" .........~
". _.-_ TheoretiMllHem~ ...n1
'. ~ Witllouf Tailing
e
CD
<J
8
,6,ppar<olIl Residual
Co r.tëlll1i:Aent
>~C~oro_.e_.en'-trn-lb-n._.~--.-----.--- --"-.'-'.---'-"-"~---i"""~
"
"-!'i',
......... '..,., ....
o~~-·-=---~-----=---=-_-·-=-----~·-·-·-=---=-=-=-=-=-=-=-=-=-=-=-=-==-=-=-=-=-=-=-=-=-=-=-~-~-~-=-=.=~=====~============~
Figure 3.4: Concentration versus pumping duration showing tailing and rebound
effect.
Figure 3.4 shows tailing and rebound effects during and after groundwater pumping. Tailing is
the result of several physical and chemical processes:
• Differential time for contaminants to be advected from the boundary of the plume to an
extraction well;
• Diffusive mass transport within spatially variable sediments:
• Mass transfer from residual solid phases in the aquifer:
• Sorption/desorption processes:
Investigation into the impact of chromium contamination in the soils and ground water underlying a manufacturing 33
plant on a coastal aquifer
Differential time for contaminants to be advected from the boundary of the plume to an extraction
well; Groundwater flows, not only in response to an extraction well, but also to the natural
hydraulic gradient. As a result, not all of the water in the vicinity of an extraction well enters the
well. There is a limited area, the capture zone, from which the water is captured, and a stagnation
point, located downgradient from the well, where the velocity toward the well equals the velocity
induced by the natural gradient. The net velocity is zero, and there is little change in the
concentration of the contaminant during the pump-and-treat remediation. In addition, the
groundwater velocity ofa volume of water moving from the edge of the plume to the extraction
well is greater than a volume of water travelling along a streamline on the outside of the capture
zone. The time it takes the contaminated water to flow is controlled by the thickness of the
aquifer, the rate of groundwater extraction, the natural groundwater gradient, and the gradient
induced or impacted by other injection/extraction wells.
Diffusive mass transport within spatially variable sediments : Geologic materials are typically
heterogeneous; groundwater moves through higher permeable layers while water in lower
permeable layers remains immobile. Contaminants that have remained in the subsurface for
extended periods of time migrate to the lower permeable layers by molecular diffusion. During
pump-and-treat, clean water is moved through the more permeable layers at a relatively high rate,
while removal of the contaminants from the lower permeable lenses is limited by the rate of
diffusion into the higher permeable layers; thus maintaining the concentration of the contaminant,
often above the established MCL.
Mass transfer from residual solid phases in the aquifer: Contaminants can exist in the subsurface
in relatively large reserves as solid phase precipitates. A likely reserve for chromium
contaminated sites is barium chromate (BaCr04), the source of the barium either coming from
contamination or from the natural soil.
Palmer and Wittbrodt (1991) conducted a study at a United Chrome Products site and suggested
that the Cr(VI)-contaminated groundwater was in equilibrium with BaCr04• Column leaching
tests of the contaminated soil showed a significant levelling of the Cr(VI) concentrations,
indicating that a solid phase may be controlling the concentration in the extraction water.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 34
plant on a coastal aquifer
Sorption/desorption processes: As discussed previously, Cr(VI) exists in solution as the anions
HCr0 24-, Cr04- , and dichromate (Cr20 27- ), and is adsorbed onto the soil matrix. As the
concentration of Cr(VI) decreases, it becomes more difficult to remove the Cr(VI).
The use of in situ technologies such as chemical enhancement of the pump-and-treat method (the
addition of reductant or extracting agent) may be desirable to overcome the tailing phenomenon
and reduce the overall time required for remediation. However, the cause of tailing at a given site
needs to be determined and quantified. For example, if the tailing is controlled by physical
processes such as differential travel time along streamlines, then chemical enhancement may not
be advantageous. Further, regulatory agencies may require the removal of the chemical enhancer.
This is especially true if the chemical enhancer or its byproducts exceeds the concentration(s) of
applicable water quality standards. Typically, chromium-contaminated sites consist of three
zones:
• source zone soils where the concentrated waste resides;
• the concentrated portion of the groundwater plume;
• the diluted portion of the groundwater plume (Sabatini et aI., 1997).
Water
Table
'"
Derived from: Rou se et al., 1996 and Sabati ni et al., 1997.
Figure 3.5: Conceptual geochemical model of zones in a contaminant plume.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 35
plant on a coastal aquifer
Figure 3.5 illustrates these three zones of contamination. Applying conventional pump-and-treat
remediation methods to all three regions would be highly inefficient. An integrated technology
approach would probably be best suited for full-scale site remediation.
3.5.3 In situ technologies
A number of in situ technologies or approaches use chemical reduction/fixation for chromium
remediation. These include geochemical fixation, PRBs, reactive zones, and natural attenuation.
Understanding the Chromium cycle presented in Section 3.2 and site characteristics presented in
Section 3.4 is critical for the use of these approaches, especially natural attenuation. Chemical
reduction/fixation remediation techniques do not remove chromium from the aquifer system, but
are designed to immobilize chromium precipitates by fixing them onto aquifer solids or reactive
media, thereby reducing chromium in groundwater. Other types of in situ treatment that are
available or under development for remediation of chromium-contaminated sites include soil
flushing/enhanced extraction, electrokinetics, and biological processes including
phytoremediation. Biological processes include bioreduction, bioaccumulation, biomineralization,
and bioprecipitation which use specific substrates to drive the treatment and effect the reduction,
uptake, or precipitation of Cr(VI) based on the principles in Section 3.2. These processes can be
utilized within PRBs and reactive zones. Phytoremediation utilizes plant uptake of chromium
contamination as the in situ treatment approach.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 36
plant on a coastal aquifer
CHAPTER 4. FIELDWORK AND DISCUSSION OF RESULTS
4.1 Hydrocensus
A hydrocensus survey was conducted in a 1 km radius of the manufacturing plant site between
November 2004 and January 2005. The purpose of the hydrocensus was to establish ifany
groundwater extraction boreholes or wells occurred in the area, and to identify the usage of the
groundwater extracted from such sources. Boreholes identified in the study area were sampled
and the groundwater was analysed to determine the concentrations of hexava lent chromium
[Cr(VI)], in order to ensure that there was no health risk to users from such sources.
The hydrocensus involved approaching landowners, tenants, residents or occupants of the
properties, explaining the reason for the survey, completing a field questionnaire and gathering
borehole information on the depth to groundwater, groundwater quantity and quality and drilling
data. The following properties were surveyed in detail:
• Turf club site.
• Industrial and commercial properties to the south-west of the plant site.
• Residential properties and associated facilities (eg. Schools, religious institutions, sports
facilities)
A multitude of boreholes were found during the hydrocensus survey as shown in Figure 4.1, and
the information obtained is summarised in Table 4.1 below.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 37
plant on a coastal aquifer
Table 4.1: Summary of hydroeensus results
Borebole Borebole Pump Pump Groundwater
Location No. depth Equipment depth capacity
level Comments
(mbgl)* (mbgl)* (mJ/hr) (mbgl)*
Has not been pumped
BH_C4 70 None 35 N/A 0.902 since 1998, presently not
used
Used for irrigation
BH_ T 193 Submersible 48 9 0.506
Turf club site (7hrs/day)
Used for irrigation
BH -DP 70 Submersible 40 6 6.374 (7hrs/day)
BH_CT N/A None N/A N/A 0.000 Presently not used
Industrial properties BH_Ar 43.46 None N/A 2 1.579 Present! y not used
(southwest of plant N/A
BH_Ca 80 None N/A N/A
site) Presently not used
N/A - Not AVailable
·mbgl - metres below ground level
Based on the results above, it is clear that there were no private boreholes found in or close to the
affected area. The boreholes found were mainly industrial boreholes in other industries around the
manufacturing plant including the turf club site. These boreholes were in the uncontaminated
aquifer and most of them were either blocked or destroyed. Only two boreholes located on the
turf club site were being utilized for irrigation. The reported groundwater levels in the identified
boreholes ranged from 0.000 mbgl to 6.374 mbgl. The chemical results of the groundwater
samples are discussed in section 4.6 below.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 38
plant on a coastal aquifer
-3313400
-3314(0)
-3314200
-4200 -3IDJ -36lJ) -3400 -3200 -:DIl -2£II) -2EiOO
o 250 500 750m
Figure 4.1: Boreholes found during hydrocensus survey.
4.2 Borehole installations
4.2.1 Introduction
A total of 113 hand auger holes and wash bore drilled boreholes were put down in phases on the
manufacturing plant site and neighbouring area over the period May 2004 to August 2005. The
boreholes were installed to establish the subsoil conditions and to facilitate the monitoring and
sampling ofthe groundwater in the various aquifers underlying the study area. The boreholes
installed during this study are summarised in Table 4.2 below, and are shown on the site plan in
Figure 4.2. The boreholes installed during this study are discussed separately in sections 4.2.2 and
4.2.3 below.
lnvestigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 39
plant on a coastal aquifer
Table 4.2: Summary of boreholes installed during this study
Borehole Borehole Numbers Installation Date Final Borehole
Series Depths (m)
10 BHI to BH39 May 2004 to March 2005 2,2 to 4,8
100 BHIOI to BH12I September 2004 to 2,65 to 5,3December 2004
BH20lA to BH225A 6,5 to 11,0
200 January 2005 to August 2005
BH201 to BH225 9,0 to 16,0
BH301 to BH318 February 2005 to March 1,6 to 3,9300 2005
400 BH401, BH402, BH403 June 2005 to July 2005 30,45 to 32,45
0 01,03,05 November 2004 to March2005 51,0 to 84,0
-3313600-
Turf club site
-3313700-
IH21
o o
8H29
o .-
SItU o
""206 "'21
o
IH2S
-3313800-
..H".."..,UA ...o14Blf~
UH o= 5211HJD)
... :lDlA ..o.. "'ê)
...... o "Bo"'o6H16W"11A o 11<17-3313900 _ Positions of boreholes
SH2l4A ... 11 o
o SHtOII .... 11110, ri~ bo,£-hol~~
o 8H217100 SI:~if:$ bOlll'lTob
200 Sl:1'1:-s bcHehole.
• 2001\ ,er" ~bo<eholc~
• 300 ~if:$ bowhole.
• 400 _ if:$ bowhob
• D~rltB bcHehob Residential
I
-3900 -3700
Q lOOm lSOm 2DOm 2SOm
Figure 4.2: Boreholes locations on the manufacturing plant site and neighbouring
area-
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 40
plant on a coastal aquifer
4.2.2 Hand auger drilling
A total of 74 hand auger holes designated BHl to BH39, BHl Ol to BH121 and BH301 to BH318
were put down in phases on the manufacturing plant site and neighbouring area over the period
May 2004 to August 2005. The locations of these boreholes are shown in Figure 4.2 above. The
hand auger holes are discussed separately below.
o Boreholes designated BH 1 to BH39 (" I0 series") were installed to investigate the subsoil
conditions, and the levels and extent of the chromium contamination in the shallow
aquifer beyond the boundaries of the manufacturing plant site. The "10 series" boreholes
were installed over the period 14 May 2004 to 12 March 2005. They were installed on
the southern portion of the turf club site and in the residential area to the south-east of the
plant site.
• Boreholes designated BH IOl to BH 121 (" 100 series") were installed over a more
widespread area than the" I0 series" boreholes described above. These boreholes were
put down to investigate the levels of chromium in the shallow groundwater aquifer
beneath the area around the manufacturing plant and residential area, and turf club site,
within an approximately 1km radius of the manufacturing plant site.
• Boreholes designated BH30 I to BH318 ("300 series") were installed on the
manufacturing plant site to investigate the levels and extent of chromium contamination
in the shallow aquifer beneath the site.
The hand auger holes discussed above were installed in the first sandy aquifer horizon using
Eijkelkamp hand augering equipment of II Omm diameter and temporary steel casing, to depths
( shown in Table 4.2 above. The piezometers installed in these boreholes comprised 63mm
diameter uPVC standpipes.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 41
plant on a coastal aquifer
Figure 4.3: Hand auger hole with temporary casing.
4.2.3 Rotary wash bore drilling
A total of39 wash bore drilled boreholes designated BH201 to BH225, BH201A to BH225A,
BH401 to BH403, BHD1, BHD3 and BHD5 were put down in phases on the manufacturing plant
site and neighbouring area over the period May 2004 to August 2005. The locations of these
boreholes are shown in Figure 4.2 above. The wash bore drilled boreholes are discussed separately
below.
• Boreholes designated BH20 I to BH225 and BH201 A to BH225A ("200 series") were
installed over the manufacturing plant site, on the turf club site and in the adjacent
residential area. These boreholes installed for the purpose of confirming the subsoil
conditions down to the "hippo mud" clay, installing groundwater monitoring and
sampling piezometers in sandy aquifers 2 and 3 m above the "hippo mud" clay and to
conduct pump tests in order to determine deep aquifer parameters.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 42
plant on a coastal aquifer
o Boreholes designated BH401 to BH403 ("400 series") were put down on the
manufacturing plant site, and were drilled down to the weathered sandstone bedrock
underlying the Harbour Beds. These boreholes were put down to prove the nature of the
subsoils underlying the "hippo mud" clay and depth to bedrock, to facilitate the
installation of groundwater monitoring and sampling piezometers in aquifer 4 above the
sandstone bedrock and to conduct pumping tests to determine the parameters and
characteristics of aquifer 4.
o Boreholes designated BH Dl, BH 03 and BH DS ("0 series") were put down to the
sandstone bedrock at the positions shown on the site plan in Figure 4.2. These boreholes
were put down to confirm the stratigraphy beneath the manufacturing plant and
neighbouring areas, to facilitate the installation of groundwater monitoring and sampling
piezometers in the deep bedrock aquifers.
The "200" and "400" series boreholes discussed above were drilled using rotary wash bore
drilling techniques. After excavation of a test pit to prove the presence of underground services, a
200mm diameter temporary steel casing was installed and sealed into the first clay layer to
prevent cross-contamination occurred between the upper aquifer above the first clay layer and the
aquifers below. A second ISOmm diameter casing was then advanced through the 200mm casing
to the final depth of the borehole. The boreholes were drilled to depths shown in Table 4.2
above. A biodegradable drilling fluid was used during the washboring process. Standard
Penetration Tests (SPT's) were carried out at 1,0 metre depth intervals as the boreholes were
advanced to determine the consistency of the soils.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 43
plant on a coastal aquifer
Figure 4.4: Rotary wash bore drilling rig.
Once the boreholes had been advanced to their final depths, the boreholes were flushed to remove
the biodegradable drilling fluid and any sediment that had accumulated in the casing as a result of
the drilling process. Piezometers were then installed in the boreholes and the temporary casing
removed. The piezometers installed in these boreholes comprised IIOmm diameter uPVC
standpipes, with O,3mm horizontal slotted screen sections which were wrapped in a nylon filter
sock to prevent the ingress of fines.
The "D" series boreholes were also drilled using rotary drilling techniques. After excavation of a
test pit to prove the presence of underground services, an HX size (114mm diameter) steel casing
was advanced, together with washboring and Standard Penetration Tests (SPT's) to a maximum
depth of IOmetres. This temporary casing was used to prevent collapse of the shallow subsoils
during drilling operations. A 150mm diameter casing was first sealed into the first clay layer to
prevent cross-contamination between the upper and lower aquifers, before the HX casing was
advanced to a depth of about 12 metres. SPT's were carried out at 1,5 metre depth intervals as
lnvestigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 44
plant on a coastal aquifer
the boreholes were advanced. Once SPT refusal occurred in the rock strata at certain depths, the
boreholes were advanced into the bedrock by NX (75mm diameter) core drilling. Final depths of
the boreholes ranged between 51 and 84 metres in the weathered Cretaceous silty sandstone or
Natal Group Sandstone
The results of the borehole installations are displayed in geological logs included in Appendix A
(selected borehole logs), and the geology underlying the site is summarized in Table 4.3 below.
~abne 4.3: Summary of geology underlying the manufacturing plant site and
neighbouring area
Depth Range of
Range of Thickness Description Layer
Top of ..• I of Layer
Layer' (m)
(mbgl*) .
0.4 to 2.1 Brown to dark grey silty SAND, containing some gravel and0 Fillrubble (FILL)
Yellowish brown / greyish brown fine to medium grained,
0.4 to 2.0 0.0 to 4.0 slightly clayey sand to clayey SAND (Harbour Beds). Aquifer I
Grey mottled yellowish brown slightly sandy to sandy CLAY
1.5 to 5.0 0.7 to 5.0 Clay Layer I(Harbour Beds).
Yellowish brown / greyish brown fine to medium grained,
2.4 to 7.4 1.0 to 6.3 slightly clayey sand to clayey SAND (Harbour Beds). Aquifer 2
7.0 to 13.3 1.0 to 3.0 Grey mottled yellowish brown slightly sandy to sandy CLAY Clay Layer 2(Harbour Beds).
Yellowish brown / greyish brown fine to medium grained slightly
9.0 to 15.0 1.0 to 6.0 clayey sand to clayey SAND. (Harbour Beds). Aquifer 3
10.1 to 16.1 8.0 to 14.5 Dark grey silty CLAY, Hippo Mud (Harbour Beds). Hippo Mud
Greyish brown fine to medium grained slightly clayey to clayey
24.0 to 29.5 1.0 to 7.7 SAND. (Harbour Beds). Aquifer 4
28.2 to 31.7 >100 SANDSTONE (Natal Group) / Cretaceous (St Lucia Formation) Sandstone
*mbgl- metres below ground level
From the above it can be seen that the fill underlying the site occurs from the surface to depths in
the range of approximately 0.4 metres to 2.1 metres below existing ground level. The fill
generally comprises brown to dark grey, silty sand to slightly clayey sand, and contains abundant
gravel and rubble in places. The fill overlies the harbour bed sediments, which generally occur in
four predominantly sandy aquifer horizons interlayered with clay layers of various composition
and thickness. The harbour beds beneath the site may be described as follows:-
• Aquifer] - This aquifer directly underlies the fill, and generally compnses
yellowish brown to greyish brown, slightly clayey to clayey sand. This subsoil
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 45
plant on a coastal aquifer
horizon extends to a maximum thickness of about 4.0 metres, and is underlain by a
clay layer, designated clay layer 1.
e Clay Layer 1 - This clay layer appears to be continuous beneath the site, occurring
at depths ranging between approximately 1.5 to 5.0 metres below existing ground
level, with a layer thickness ranging from approximately 0.7 to 5.0 metres. This
layer generally comprises grey mottled yellow brown, slightly sandy to sandy clay,
and is underlain by the sandy soils of Aquifer 2.
e Aquifer 2 - This aquifer generally comprises yellow brown to greyish brown,
slightly clayey sands and clayey sands, occurring below the base of clay layer 1 at
depths of between approximately 2.4 to 7.4 metres. The Aquifer 2 subsoils range in
thickness between approximately 1.0 and 6.3 metres. Aquifer 2 contains occasional
localized thin lenses of clay.
I') Clay Layer 2 - This layer, comprising grey mottled yellow brown, slightly sandy to
sandy clay, occurs between Aquifers 2 and 3 at depths of between approximately
7.0 and 13.3 metres. The thickness of this clay layer ranges between approximately
1.0 to 3.0 metres.
o Aquifer 3 - This aquifer comprises yellowish brown to greyish brown, slightly
clayey to clayey sand, and occurs at depths in the range of approximately 9.0 to
15.0 metres, below Clay Layer 2. Occasional localized silty clay lenses occur within
this aquifer. The thickness of the Aquifer 3 horizon ranges between approximately
1.0 and 6.0 metres. Aquifer 3 is underlain by the "hippo mud" clays.
• Hippo Mud - These typically soft, dark grey silty clay deposits range in thickness
between approximately 8.0 to 14.5 metres, occurring at depths of between
approximately 10.1 and 16.1 metres below existing ground level beneath the
manufacturing plant site. The "hippo muds" form a relatively impermeable aquitard
between Aquifer 3 and Aquifer 4.
o Aquifer 4 - This aquifer occurs below the "hippo mud" clays at depths of
approximately 24.0 to 29.5 metres. Aquifer 4 comprises greyish brown slightly
clayey to clayey sand, interlayered with localised clay lenses in places. The
thickness of Aquifer 4, which represents the deepest harbour bed deposits, ranges
between approximately 1.0 and 7.7 metres.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 46
plant on a coastal aquifer
The harbour bed sediments described above, overlie sandstone of the Natal Group or sandy
siltstones of the St Lucia Formation at depths of between approximately 28 and 32 metres below
existing ground level on the manufacturing plant site. The weathered sandstone immediately
below the harbour beds generally comprises residual, highly weathered, orange brown, slightly
clayey to silty sand. With depth the sandstone typically becomes less weathered, grading into
pinkish maroon sandstone bedrock which extends to depths in excess of 100 metres below the
site.
4.3 Materials testing of soil samples
4.3.1 Hydraulic conductivity estimation based on grain size analysis
Eighteen representative soil samples recovered during the installation of boreholes on the plant
site and surrounding area were selected and submitted to commercial materials testing laboratory
for grading analysis. This was done in order to characterize the soils in terms of their particle size
distribution and clay content and to compare the results to the soil profile given on the borehole
logs. Soils samples were taken at selected depths from the Standard Penetrometer Test (SPT) split
spoon sampl ing carried out during the installation of boreholes.
Based on the grain-size analysis, hydraulic conductivities of soils were estimated using various
empirical equations discussed below. Kozeny-Carman empirical equation:
g -3 n 2
K=-;x8.3xlO [ (I-nY3 ] a;
Where:
K = hydraulic conductivity (m/day)
g = acceleration due to gravity (m/sec')
v = kinematic viscosity (m2/day)
n = porosity (dimension less)
dlQ= effective grain diameter (mm)
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 47
plant on a coastal aquifer
porosity (n) may be derived from the empirical relationship with the coefficient of grain
uniformity (U) as follows:
n = 0.255(1+ 0.83u)
where U is the coefficient of grain uniformity and is given by:
The Kozeny-Carman equation is one of the most widely accepted and used derivations of
hydraulic conductivity as a function of the characteristics of the soil medium. This equation was
originally proposed by Kozeny (1927) and was then modified by Carman (1937, 1956) to become
the Kozeny-Carman equation .It is not appropriate for either soil with effective size above 3mm
or for clayey soils (Carrier 2003).
Sherard et al (1984) developed the following equation:
Where:
K = hydraulic conductivity (m/day)
dis = represents the size at which 15% of the sample is smaller (mm)
Alyamani and Sen (1993) proposed calculating the hydraulic conductivity using the following
equation:
K = 0.015[10 + 0.025(dso - dlO)f
Where:
K = hydraulic conductivity (m/sec)
lo= intercept of the line formed by dsoand dlO with the grain size axis (mm)
dso= median grain diameter (mm)
dlO= effective grain diameter (mm)
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 48
plant on a coastal aquifer
The results of the particle size distribution analysis of the soil samples are given in Appendix B,
and summarized in Table 4.4 below. The results of the estimated hydraulic conductivities from
the grain size analysis using the three empirical formulae discussed above are summarized in
Table 4.5 below.
Table 4.4: Summary of particle size distribution analysis
.S.a.m.plc''N':i)!;'''~~- ''~:'I ":.:t, :,:,:,!~\{#~,t·:...,...:.~:.,l~;,<,'S'''~_: Pc~;'~)~/I';I~·~·~:·< _:; :~':'~,; i·~,,,:I'.;:",i,(~J1'Il~1ic~le)s:, ~"iz.?e\(%~, ) ',~.., 4\'1: ~,
.. ,"'~~~;_J, '~"~';', "'',,') ',:' "";,.:, ..>,.")!·,\ -,.,,l:.,,ClaY"·:··'Sllt··,~",Sai1d';'GraveF'
BH202(1m~ ",-...;_;;~___;'-t--'-'-'"'':;;S'7A~N';::D--''--''---p----'-~--'--r:;';;8~t-=-'';3:'-'-t=~87==t-'-'';.:_2~"--l
BH210 (3m) Aquiferl Silty SAND 8 5 72 16
~B~H2~0~9~~~m~I)_;- +-_~~S~AN~D~ __ ~ 4 2 86 8
BH202 (2m) Sandy CLAY 24 6 70 0
BH201 Srn Aquitard I Sandy CLAY 29 13 58 0
t-;'::B:-:H2:::04~=5m+_t- +-_--=S:.::an:..:;d?77y_C_==L::---Al :_:Y 53 14 33 0
BH204 7m SAND 8 2 86 4
BH205 7m Aquifer 2 SAND 6 8 84 2
I--:::-BH2:-::=-:0~2~(8::::m"'-:--t -+_--=.,--.;;.S:..:AN:,=D:::--:-:-:----l 11 5 81 3
BH204 (JOm) Silty Sandy CLAY Harbour bed 23 12 65 0
BH205 (lOm) Aquitard 2 Sandy Silty CLAY sediments 31 18 51 0
r=-BH2:-=-:0:,,-2-71~I.;_;_m7-);- +-_--=S.;;;;an.;.;:diL,-=-yC,::cLA;_;;Y';;'__--1 30 II 59 0
BH201 (IIm) SAND 10 6 81 3
BH203 (13m) Aquifer 3 Silty SAND 10 16 68 5
BH202 (16m) Silty SAND 9 22 61 8
I--:::-B:-::H2=-:0-t~--5---7-+(1-=-S=;2;-;:';i_-:mc'l7l)ty ::":'S?an'-'d7jy':=:C';:;L'-:Ac;'y.,----i 21 10 69 0
BH201(14m) Aquitard3 Sandy CLAY 19 21 60 0
t-;'::B:-:H2::;::0:.::;2'-;(:-:16;:-:m'7--tI-}'S--::-,f:I""=i-ig::htt::.llyS.:::.lan=:::=dy~Si:.::;lty'-C.:::.L=:A.9:..Y:......2j2 68 I
BH401 (27m) SAND 0 13 81 6
BH403 (27m) Aquifer 4 SAND 2 14 84 0
BHOI (27m) SAND 9 6 85 0
BHD5 (27m) Sandstone SAND 2 2 95 IBH03 (30m) SAND Natal Group 6 3 86 5
BHDI (3Im) Aquifer SAND 6 0 94 0
Table 4.5: Hydraulic conductivities estimated from grain size analysis using
empirical formulae
Samp·l·~·'·~":ó'·7":B' COCir(_fi',"il,:: ') dis d50 doo (~) . I. Hydraulic conductivi y (inId)(mm) (mm) (mm) (U),';"/"f>,, ',.lIJm (mm) x-c. Sherard AIS
BH202 (1m) 0.007 0.07 0.16 0.19 27.142 0.257 0.0034 0.010 0.015 0,068
BH210(3m) 0.01 0.07 0.18 0.23 23 0.259 0.0049 0.022 0.015 0.109
BH209(4m} 0.08 0.09 0.19 0.23 2.875 0.404 0.068 8.275 0.024 6.487
BH204(7m) 0.005 0.08 0.17 0.2 40 0.255 0.0022 0.005 0.019 0.052
BH205 (7m) 0.013 0.065 0.155 0.18 13.846 0.274 0.0063 0.046 0.013 0.126
BH202(8m} 0.0016 0.055 0.15 0.18 112.5 0.255 NA 0.001 0.009 NA
BH201 (1Im) 0.002 0.04 0.17 0.18 90 0.255 NA 0.001 0.005 NA
BH203 (13m) 0.001 0.004 0.15 0.17 170 0.255 NA 0.0002 0.00005 NA
BH202 (16m) 0,004 0.015 0.07 0.085 21.25 0.260 0.0016 0.004 0.001 0.014
BH401 (27m) 0,02 0.065 0.157 0.19 9.5 0.298 0.013 0.150 0.013 0.350
BH403 (27m) MI5 0.05 0.156 0.19 12.667 0.279 0.0085 0.065 0.008 0.187
BHOI (27m) 0,006 0.015 0.065 0.07 11.667 0.284 0.0033 Mil 0.001 0.030
BH05 (27m) 0.03 0.035 0.065 0.065 6 0.338 0.025 0.553 0.004 0,868
BH03 (30m) 0.07 0.08 0.18 0.21 0.929 0.469 0.05 12.517 0.019 3.606
BHOI(3lm) 0.04 0.055 0.07 0.07 5.25 0.351 0.032 1.140 0,009 1390
K-C=Kozeny-Carman; AIS =Alyarnani& Sen; NA - Not Available
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 49
plant on a coastal aquifer
Based on Table 4.4 above, it can be seen that the aquifer layers typically have higher sand
contents than the clay layers, whilst the clay layers generally show higher contents of soil fines
i.e. clay and silt, as expected. However, the variation of the various soil fractions identified in the
laboratory tests within specific soil layers is substantial, particularly within the clay layers where
clay contents range between 9 and 53% and sand content between 33 and 95%, although these
layers were identified from field samples to comprise predominantly clays. Such occurrences of
lower than expected clay content, and higher than expected sand contents within the clay layers,
resulting from the laboratory particle size distribution analysis, can be attributed to the following:
o The erratic occurrence of sand lenses within the clay sediments, as is typical of the
harbour bed sedimentary deposits.
e The characteristic under-estimation of the clay content of such estuarine sediments,
as is often experienced in the hydrometer analysis of soil fines on such materials,
presumably due to the soil particle characteristics and behaviour under dispersion.
This is particularly relevant to the hippo mud clays, where the test results reflect a
clay content in the range 9 to 21%, considered to be a severe underestimation.
4.3.2 Hydraulic conductivity estimation based on laboratory tests
The empirical formulae discussed in section 4.3.1 above are not appropriate for estimating
hydraulic conductivity of clayey soils. Therefore the hydraulic conductivity of clayey soils, were
estimated using the laboratory tests. The recovered continuous samples were consolidated and
recompacted in the laboratory to densities approximating the insitu densities. These samples were
then subjected to constant head permeability tests.The results of the estimated hydraulic
conductivities from the laboratory tests are summarized in Table 4.6 below.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 50
plant on a coastal aquifer
Table 4.6: Hydraulic conductivity of clayey soils based on laboratory tests
Particle size (%) Bulk** Hydraulic
Sample No. Unit Soil type Clay Silt Sand Gravel density conductivityp.,(kg/m3) K (mld)
BH202 2m) Sandy CLAY 24 6 70 0 1566 0.0000963
BH104 (Sm) Aquitardl Sandy CLAY 53 14 33 0 1587 0.0000422
BH201 Sm) Sandy CLAY 29 13 58 0 1594 0.0000865
BH104 lOm) Silty Sandy CLAY 23 12 65 0 1619 0.0000960
BH205 lOm) Aquitard 2 Sandy Silty CLA Y 31 18 51 0 1618 0.0000958
BH202 Ilm) Sandy CLAY 30 II 59 0 1625 0.0000964
BH205 (12m) Silty Sandy CLAY 21 10 69 0 1630 0.000864
BH201 (I4m) Aquitard 3 Sandy CLAY 19 21 60 0 1646 0.000874
BH202 (16m) SlightlySandy Silty CLA Y 9 22 68 I 1660 0.000996
mbgl - meters below ground level
·Samples consolidated from consecutive Standard Penetration Test (SPT) recoveries at approximate depths given
""Laboratory recompaction to approximate insitu densities based on SPT results
The results of the laboratory tests in Table 4.6 above show a general reduction in hydraulic
conductivity with an increase in density (and depth) as could be expected.
4.4 Borehole pumping tests
A total of sixteen "200 series" boreholes were selected for pumping tests in order to determine the
aquifer parameters and groundwater flow characteristics in the intermediate and deep aquifers,
referred to as Aquifer 2 and 3, respectively. Of the 16 pumping tests, 9 tests were conducted in
the "200A series" boreholes to target aquifer 2. The remaining 7 pumping tests targeted aquifer 3
in the "200 series" boreholes. In addition, a pumping test was conducted in borehole BH403.
This test was conducted to target the aquifer below the" hippo mud clay" (Aquifer 4). The
boreholes selected for the pumping tests are shown in Table 4.7 below.
Table 4.7: Boreholes selected for pumping tests
A uifer . 'Borehole number
2 BH203A, BH212A, BH204A, BH205A, BH215A, BH207A, BH206A,BH221A and BH217A
3 BH203, BH205, BH207, BH213, BH206, BH208 and BH217
4 BH403
All pumping tests were conducted as follows:
• Prior to the test, the final depth and static groundwater level were measured in the
borehole using a Heron interface probe.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 51
plant on a coastal aquifer
uv . UFS
BLOEMFONTEIN
BIBLIOTEEK - LIBRARY
o The test pump was installed in each borehole at the maximum depth possible to
optimise the available drawdown. This was influenced by the final depth of each
borehole and the set lengths of rods connecting the line shaft pump to the motor.
Step drawdown tests, which generally comprised four 1 hour steps at incremental
increases in pump discharge rates were conducted. The purpose of the step test was
to predict a constant discharge pumping rate, based on the observed drawdown
curves obtained during the steps. Ideally a drawdown of between 60% and 75% of
the available drawdown should be achieved at the end of the constant discharge
pumping phase.
o The step tests were followed by monitoring the recovery of the groundwater in the
borehole to the original static groundwater level measured prior to commencing the
test.
o Following the recovery stage of the pumping test, the boreholes were pumped for a
period of 24 hours at the constant discharge rate. The constant discharge rate was
predicted from the step test stage.
• Following the constant discharge pumping stage, the pump was switched off and
the recovery of the groundwater was monitored in the pumped wells. The recovery
was monitored generally to within 90% to 100% of the original static groundwater
level measured in the boreholes prior to testing. For most boreholes, the recovery
to this condition took the same amount of time as the period of constant discharge
pumping.
The results of the pump test data were analysed to determine the transmissivity of the respective
pumped aquifers, and hence the hydraulic conductivities. The transmissivity of an aquifer is a
measure of how much water can be transmitted horizontally, and is directly proportional to
hydraulic conductivity and aquifer thickness.
Transmissivity : T = KD (Kruseman et al 1991)
Solving fo K gives,
K=T/D
Where:
T = Transmissivity (m2/d)
K = Hydraulic conductivity (m/d)
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 52
plant on a coastal aquifer
0= Aquifer thickness (m)
The transmissivity values were estimated from the pump test data that was captured into the Flow
Characteristic Method (Van Tonder et aI200I). The results of the analysis of the pump test data
are given in Appendix C, and are summarized in Table 4.8 below.
Table 4.8: Summary of results of analysis of borehole pump tests
Maximum
Borehole No. Unit Pump rate drawdown Transmissivity
Hydraulic
(I/hr) (mz/d)(m) conductivity (mId)
BH204A 90 2.3 0.55 0.18
BH205A 36 2.3 0.25 0.04
B1-I206A 36 4.8 0.05 0.02
B1-I207A Aquifer 2 54 3.3 0.24 0.05
BH212A 288 5.1 0.67 0.12
BH215A 90 3.4 0.40 0.14
B1-I221A 216 2.8 1.05 0.29
Mean h draulic conductivity 0.12
B1-I203 252 6.7 0.92 0.12
B1-I205 108 5.7 0.47 0.12
B1-I206 216 5.1 0.95 0.16
B1-I207 Aquifer 3 324 4.7 1.45 0.48
B1-I208 792 6.4 2.32 0.33
B1-I213 648 6.7 1.54 0.5
B1-I217 288 4.5 1.81 0.3
Mean hydraulic conductivity 0.29
B1-I403 Aquifer 4 180 5.8 0.14 0.02
From the above it can be seen that the estimated aquifer transmissivities ranged between the
values of 0.05 m2/d to 1.05 m2/d in aquifer 2 and 0.47m2/d to 2.32 m2/d in aquifer 3. The
estimated aquifer transmissivity value of 0.14 m2/d was reported in aquifer 4. The estimated
hydraulic conductivities ranged between the values of 0.04 mid to 0.29 mid in aquifer 2 and 0.12
mid to 0.48 mid in aquifer 3. The hydraulic conductivity value of 0.14 mid was estimated in
r aquifer 4. The average results of the estimated hydraulic conductivities using the three methods
mentioned above (section 4.3 and 4.4) are summarized in Table 4.9 and discussed below.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 53
plant on a coastal aquifer
Table 4.9: Summary of estimated! hydraulic conductivities for various aquifers
underlying the manufacturing plant
. Particle size (%) Average', ,'"'-,.'HydraulicSampl , Unit Soil type Soil origin, , Clay, Silt Sand Gravel conductivity':~~.;,~,:~ ;'-<;; <.k-,"~,: ~ (mld)BH202(lm_l ' SAND 8 3 87 2
BH210(3m) Aquiferl SiltySAND 8 5 72 16 1.67
BH209 (4m) SAND 4 2 86 8
BH202(2m). Sandy CLAY 24 6 70 0
BH201 (5m) Aquitard I Sandy CLAY 29 13 58 0 0,000082
BH204 (5m) Sandy CLAY 53 14 33 0
BH204(7m) SAND 8 2 86 4
BH205 (7m) Aquifer 2 SAND 6 8 84 2 0.12
BH202 (8m) SAND II 5 81 3
BH204(IOm) Silly Sandy CLA Y 23 12 65 0
Harbour bed
BH202 (llm) Aquitard 2 Sandy CLAY sediments 30 II 59 0
0.000097
BH205 (lOm) Sandy Silty CLAY 31 18 51 0
BH101 (Ilm) SAND 10 6 81 3
BH203 (I3m) Aquifer 3 SiltySAND 10 16 68 5 0.29
BH202(16m) SiltySAND 9 22 61 8
BH205 (Ilm) Silly Sandy CLAY 21 10 69 0
BH201 (I4m) Aquitard 3 Sandy CLAY 19 21 60 0 0.000911
BH202(16m) SlightlySandy Silty CLAY 9 22 68 I
BH401 (27m) SAND 0 13 81 6
BH403 (27m) Aquifer4 SAND 2 14 84 0 0.02
BHDI (27m) SAND 9 6 85 0
BHD5 (27m) SAND 2 2 95 I
BHD3 (30m) Sandstone Natal Group 6 3 86 5 2.23
Aquifer SAND
BHDI (3Im) SAND 6 0 94 0
Based on the estimated hydraulic conductivities in Table 4.9 above, it is clear that the sandstone
aquifer had higher hydraulic conductivity than the harbour bed sediments which generally occur
in four predominantly sandy aquifer horizons (aquifers 1,2,3 and 4). This means that the
movement of groundwater in the sandstone aquifer would be faster than in the harbour bed
sediments. Of the harbour bed sediments, aquifer 1 had higher hydraulic conductivity, suggesting
that it would easily transmit water more than the other sandy aquifer horizons (aquifers 2,3 and
4).
The aquitards interlayering different sandy aquifer horizons had very low hydraulic conductivities
and this implies that groundwater movement through these layers would be very slow hence it is
suspected that contamination could diffuse through these layers.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 54
plant on a coastal aquifer
4.5 Groundwater level monitoring
Groundwater levels (piezometric levels) were monitored in the existing boreholes and new
boreholes put down on the manufacturing plant site and surrounding area on a monthly basis. The
purpose of the groundwater level monitoring was to establish groundwater flow patterns within
the manufacturing plant site and the surrounding area. The groundwater levels were measured
using a dip meter as shown in Figure 4.5 below.
Figure 4.5: Groundwater level monitoring using a dip meter.
The recorded groundwater levels in the boreholes are included in Appendix D, and summarized
in Table 4.10 below. Graphical plots of groundwater level monitoring data are presented in
Figures 4.6 to 4.10, and categorize boreholes per aquifer.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 55
plant on a coastal aquifer
Table 4.10: Summary of measured groundwater levels in the boreholes
Piezometric level (mbel)
Unit Soil type Soil origin Borehole Numbers Average Range
Aquifer I Sand BH301 to BH318 1.597 o to 3.321
Aquifer2 Sand Harbour bed BH20lA to BH225A 1.248 o to 2.093
Aquifer 3 Sand sediments BH201 to BH225 1.626 o to 3.286
Aquifer4 Sand BH401, BH402, BH403 2.125 1.361 to 3.474
Sandstone Sand
Aquifer Natal Group DI,D3,D5 14.322 1.354 to 36.07
mbgl = meters below ground level
Based on Table 4.10 above, it is evident that shallow groundwater levels occurred at the average
depths of approximately 1.2 mbgl and 1.6 mbgl in aquifer 2 and aquifer 1 respectively. Deep
groundwater level occurred at an average depth of approximately 14 mbgl in the sandstone
aquifer. This suggests that aquifer 1 and aquifer 2 could be more vulnerable to hexavalent
chromium [Cr(VI)] contamination through washout of soluble Cr(VI) in the soils by high
groundwater table, than aquifers 3,4 and sandstone aquifer.
Based on the chemical results ofCr(VI) (refer to Appendix E), it is evident that Cr(VI)
concentrations were always higher in aquifer 1 and aquifer 2 as compared to the concentrations of
Cr(Vl) in aquifer 3, 4 and sandstone aquifer.
The graphical plots of monitoring data (Figures 4.6 to 4.10) indicate that the groundwater levels
have remained relatively constant throughout the study period of approximately 5 years, and in
most boreholes the groundwater level fluctuations were less than 0.5 meters. This clearly suggests
that the groundwater flow could be close to steady state. The graphical plots of monitoring data
also indicate that the notable response in some boreholes could be associated with seasonal
groundwater fluctuations.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 56
plant on a coastal aquifer
Groundwater levels in boreholes in aquifer 1 (300 series boreholes)
o
-+-8H301
~'H)Ol
__ 8H10l
--8H)O.I
~8H307
__,._BH:UO
__ 8"311
8HlU
8H)U
8H115
8H)!'
4
Figure 4.6: Groundwater levels in aquifer 1 boreholes.
Groundwater levels in boreholes in aquifer 2 (200A series boreholesl
o
-aH20JA
I... ~'"202A
> 1
.!!
3
ec:
J!
:! --aH2QtI.
.30..: 2 ____ '"UIA
oD
j
.~!!
!• --&H217A.3.!.:
c:
:s s "'2J'"
0
~
4
Figure 4.7: Groundwater levels in aquifer 2 boreholes.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 57
plant on a coastal aquifer
Groundwater levels in boreholes in aquifer 3 (200 series boreholesl
o
.. -8H20J~. -'Mm:.- 1.!?..... --lH2O$
~~
0:: _IH2JO
.~. --lH:!H3:.0. 2 ..... --lH216..<:t
:.- lH217
..~.!.! ... 21'
too
.3..:. lH219
~0:: 3e lH210
I!)
'H212
4
Figure 4.8: Groundwater levels in aquifer 3 boreholes.
Groundwater levels in bore holes in aquifer 4 (400 series boreholesl
o
_--
_IH.,J
_____ .HJOl
aH-1Ql
4
Figure 4.9: Groundwater levels in aquifer 4 boreholes.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 58
plant on a coastal aquifer
Groundwater levels in boreholes in Natal Group aquifer
o
~*.* ......*..~*. .to * ..• .to ..
4
__ IHOI
_____ 'HDJ
_ 'HDS
............... ~ . • •
40
Figure 4.10: Groundwater levels in Natal Group aquifer boreholes.
Based on the recorded groundwater levels (piezometric levels) in the boreholes (see Appendix D),
the standing water elevations were determined. It was assumed that the groundwater level
distribution generally emulates the surface topography and therefore the contaminated
groundwater would flow from a topographic high to a topographic low. The Bayesian
interpolation technique, which uses the possible relationship between the topography and
groundwater levels, was used to interpolate groundwater levels and therefore the groundwater
flow directions. Figure 4.11 presents the topography against the groundwater elevations.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 59
plant on a coastal aquifer
Topocraphy vs Groundwater levels (Aquifer 1)
20
15 .»
:.
~'" 1
£. t
s>:- 10 ....
.Cl.:1.:.
0
Cl.
0 ?
l-
S
0 I-- ï
0 5 10 15 20
Groundwat4!rlevels ImMSl)
Figure 4.11: Correlation between topography and groundwater levels in aquifer 1.
The interpolated groundwater levels in various aquifers underlying the manufacturing plant and
the surrounding area are presented diagrammatically in Figures 4.12 to 4.16 as contours with flow
directions (based on monitoring data of December 2007). From the groundwater level contour
plots, it is evident that the direction of groundwater flow in aquifers 1 to 3 was from the west to
the east. Within Aquifer 4 and the sandstone formation the groundwater flow was from the north
west to the south east in principle corresponding to the general regional groundwater flow at
depth from the hills toward the sea.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 60
plant on a coastal aquifer
-4050 -4000 -3950 -3900 -3850 -3800 -3750 -3700 -3650 -3600 -3550 -3500
Figure 4.12: Groundwater levels and flow directions within aquifer 1.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 61
plant on a coastal aquifer
-4050 -4000 -3950 -3900 -3850 -3800 -3750 -3700 -3650 -3600 -3550 -3500
Figure 4.13: Groundwater levels and flow directions within aquifer 2.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 62
plant on a coastal aquifer
-331
-331
-331
-331
-331
-4050 -4000 -3950 -3900 -3850 -3800 -3750 -3700 -3650 -3500
Figure 4.14: Groundwater levels and flow directions within aquifer 3.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 63
plant on a coastal aquifer
-4050 -4000 -3950 -3900 -3850 -3800 -3750 -3700 -3650 -3600 -3550 -3500
Figure 4.15: Groundwater levels and flow directions within aquifer 4.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 64
plant on a coastal aquifer
-4050 -4000 -3950 -3900 -3850 -3800 -3750 -3700 -3650 -3600 -3550 -3500
Figure 4.16: Groundwater levels and flow directions within sandstone aquifer.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 65
plant on a coastal aquifer
4.6 Groundwater sampling
The sampling of the groundwater from both existing and new boreholes was carried out in
various sampling events over the period June 2004 to December 2007, in order to determine the
levels and extent of chromium contamination in the groundwater underlying the manufacturing
plant and neighbouring area. The locations of boreholes are shown in Figure 4.2.The boreholes
were purged and sampled using a peristaltic pump and flow through cell for the determination of
well head parameters in accordance with the US EPA (1996) Low Flow sampling procedure.
Figure 4.17: Groundwater sampling using peristaltic pump and flow through cell
Groundwater sampling was carried out as follows:
• The standing water levels in all of the boreholes were measured and recorded prior to the
commencement of any work on each borehole.
• The boreholes were then purged by pumping a volume of groundwater that was equal to
three times the measured volume of water present in the borehole. Purging is necessary
because a groundwater sample must be representative of the formation (aquifer) water.
This is because water that has been standing in the borehole above the borehole is
o Not free to interact with water formation
o In contact with borehole construction material (i.e.,casing) for long period of
time
o Jn direct contact with the atmosphere which is then subject to different chemical
equilibria.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 66
plant on a coastal aquifer
o The boreholes were purged at a very low rate in order to avoid:
o Cone of depression (caused by lowering the water table)
o Turbulence that would cause dilution in the water and then mask the presence of
contamination
o Exposure of portion of formation (aquifer) materials to air and other gases
o Drawing of contamination to boreholes which do not intersect contamination
plume, since this causes wide spreading of contamination.
e The boreholes were purged until the pH, EC, Redox potential and temperature stabilised
in accordance with the specified range for each parameter given in the sampling
procedure.
e When the water quality parameters of three conservative measurements met the set
criteria, samples of adequate volume were collected and sent to the selected laboratory
for analysis.
• The analysis of groundwater samples included the determination of the pH, total
chromium and hexavalent chromium [Cr(VI)] .
The results of the analysis carried out on the ground water samples are given in
Appendix E, and the maximum concentrations of hexavalent chromium reported in the
groundwater in the individual boreholes installed in aquifers 1,2,3,4 and Natal Group aquifer are
indicated in colour coded dots in Figures 4.18 to 4.21 below. Note that some of the private
boreholes could not be sampled during the sampling events due to the absence of the owners. The
sampling events were done in a frequency of a one monthly basis.
Based on the chemical results in Appendix D and colour coded dots indicated in Figures 4.18 to
4.21 below, it is evident that significant concentrations of hexava lent chromium were detected in
aquifers I and 2 underlying old closed or dismantled production facilities on the manufacturing
plant site where sodium dichromate (SDC) liquid was produced or handled between 1945
and 1991. Hexavalent chromium was only detected in aquifer 3, in the limited area underlying the
manufacturing plant, immediately above the "Hippo mud" clay. In the aquifers below the "Hippo
mud" clay, aquifer 4 within the harbour bed sediments and especially within the sandstone
bedrock where ground water is extracted for irrigation at the turf club site, no hexavalent
chromium was detected.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 67
plant on a coastal aquifer
It is therefore clear that the dissolved groundwater plume in the area underlying the
manufacturing plant was identified as a secondary source of chromium contamination.
-3313600-
Turf club site
-3313700-
o o
IOHl!I
o -
IHU -o o
IHZS
-3313800-
• ...•10
• 1HlU •IIOU '"113
8H307
1IH•J1O o
IIIfi
-3313900- CliVI) (mg/I]
0<0.02
00.021010
1010100
.100101000 o
• 1000 \0 10000 8Hl1
• >10000 Resid ntial IQ.
I I I
-3900 -3800 -3700 -3600
Om 50 no 100 m 150m 200m 250 m
Figure 4.18: Maximum hexavalent chromium concentrations within aquifer 1 for the
sampling events 14 to 24.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 68
plant on a coastal aquifer
-3313600-
Turf club site
-3313700-
-3313800-
-3313900- Cr(VI) (mg/I]
o <0.02 mg/l
o 0.02 to 10 me/I
10 to 100 msll
• 100 to 1000 mul
• 1000 LOlOOOOrnelI
• >10000 mell Residential ~
I I I
-3900 -3800 -3700 -3600
Om SO m lOOm lSOm 200m 2S0m
Figure 4.19: Maximum hexavalent chromium concentrations within aquifer 2 for the
sampling events 14 to 24.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 69
plant on a coastal aquifer
-3313600-
Turf club site
-3313700-
-3313800-
-3313900- Cr(VI, [mgflJ
o <0.02
00.02\010
10 \0100
.100\0 1000 o
• 1000 10 10000 1IH2l1
• >10000 Resid ntial
I I
-3900 -3700 -3600
Om SOm lOOm ISO m ZOOm Z50m
Figure 4.20: Maximum hexavalent chromium concentrations within aquifer 3 for the
sampling events 14 to 24.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 70
plant on a coastal aquifer
-3313600-
Turf club site
-3313700-
-3313800-
-3313900- Cr(VI, [mgfl]
o <11.02
o 0.02to 10
la to 100
.1ooto1ooo
• 1000 lo 10000
• >10000
I I
-3900 -3800 -3600
Om SOm lOOm 150 m 200m 250 m
Figure 4.21: Maximum hexavalent chromium concentrations within aquifer 4 for the
sam pling events 14 to 24.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 71
plant on a coastal aquifer
4.7 Soil sampling
The soils underlying the manufacturing plant site and neighbouring area were sampled in order to
investigate the nature of the shallow subsoil materials and to determine the levels and extent of
chromium contamination. A total of 41 test pits, designated TPI to TP45, were excavated across
the manufacturing plant site, and 12 test pits, designated SOl to S 12 were excavated in the
neighbouring area adjacent to the manufacturing plant. The locations of test pits are shown in
Figure 4.22.
-3313600-
Turf dub site
-3313700-
0
~1
D
Sl
0 0o lP18Tf'll .h} TPZr;JQ,
-33138.00- nu;
1PlOD TPP
TP 0
~ 0'1'38
fYOW36 001P44 0
"lS "..I;l fP40 So
Tbl 0S1
-3313900- T0P41 0'l'Ol
0
SlO
0
S11
SDil
I I I I
-3900 -3800 -3700 -3600
o nl SO lOOm lSOm 200m 2S0m
Figure 4.22: Soil sampling locations on the manufacturing plant site and
neighbouring area.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 72
plant on a coastal aquifer
The test pits were excavated by hand to depths of 1.0 metres below existing ground level or to a
depth where the groundwater was encountered. Some of the test pits were located in paved areas,
necessitating the removal of the concrete or asphalt paving by saw cutting and breaking out of the
surfacing. The soil samples were taken at 0.3 metres ("shallow samples") and at 0.6 metres
("deep samples") in each test pit. The soil samples were then submitted to the selected laboratory
for analysis, and the analysis generally included the determination of the pH, total chromium and
hexavalent chromium [Cr(Vl)] content of the soil. The trivalent chromium [Cr(IIl)] results were
then computed by subtracting the analytical results for hexavalent chromium [Cr(VI)] from total
chromium (Total Chromium - Hexavalent Chromium).
The results of the analysis carried out on the soil samples are given in Appendix F, and the
concentrations of Cr(JII) and Cr(VI) reported in the individual test pits at different depths are
indicated in colour coded dots in Figures 4.24 to 4.27 below.
Figure 4.23: Test pit excavated for shallow soil sampling.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 73
plant on a coastal aquifer
Based on the results of the analysis carried out on the soil samples in Appendix F, and the colour
coded dots in Figures 4.24 to 4.27 below, it is evident that significant concentrations ofCr(III)
and Cr(VI) were detected in the soils underlying the old closed or dismantled production facilities
where sodium dichromate (SDC) liquid was produced or handled between 1945 and 1991 at the
manufacturing plant site. Within the residential area and turf club site, low levels ofCr(lTI) and
Cr(VI) were detected in the soil samples and this contamination could be due to the historical
surface run-off from the manufacturing plant site. It is therefore clear that the impacted
subsurface soils (>O.3m) in the area underlying the manufacturing plant site were found to be the
secondary source of contamination.
-3313600-
Turf club site
-3313700-
-3313800-
,p
0
ss
-3313900-
P.
100 l 1000
.100010 .wooo
.10000 LO1!lOOOO
.>l!lOOOO 0
Sll
I I I I
-3900 -3800 -3700 -3600
Om 50 lOOm 150 WOm 250
Figure 4.24: Trivalent chromium concentrations in the soils at the depth of O.3m.
investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 74
plant on a coastal aquifer
-3313600-
Turf club site
-3313700-
o
S2
-3313BOO-
-3313900 -.-- -,
Cr{III) [mg/kg]
oo <0.02 fSOl)O.02lO1DO
100 lo 1000
.1000 10000
.1DDDO lo 100000 0
.>1fJOOOO R i ential nl p.
I I I I
-3900 -3800 -3700 -3600
Om 5001 20001 250m
Figure 4.25: Trivalent chromium concentrations in the soils at the depth of O.6m.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 75
plant on a coastal aquifer
-3313600-
Turf club site
-3313700-
o
S2
-3313800-
Tl'J<•0 WI6 o
lPl5 ~
TP
S7
-3313900-.,...- -, o 0
lP4l "",42
Cr(VI) [mg/kg) 0
o SlOo <M20.02l010
10to 100
lOOlo 1000 Residential
.1000 10 10000 0
.>10000 su Id
I I I
-3900 -3800 ·3700 -3600
Om Sam lOOm ISDm 200m 2S0m
Figure 4.26: Hexavalent chromium concentrations in the soils at the depth of 0.3.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 76
plant on a coastal aquifer
-3313600-
Turf club site
-3313700-
o
sz
-3313800-
TP}
TP3lI
Tl' 0 ,,* • 0Tl>A4Olm ,o.
nH Tl'
TiJ
• 0
-3313900-.r---------, lP41 TP·U
Cr(VI) [mg/kg]
oo <1).02O.o2lol0
lOl01OO
.100 to 1000
.1000 10 10000 0
.>10000 su 0
lu
I I I
-3900 -3800 -3700 -3600
Om Sam lOOm ISO m 200m 250m
Fiaure 4.27: Hexavalent chromium concentrations in the soils at the depth ofO.6m.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 77
plant on a coastal aquifer
CHAPTER S. CONCEPTUAL SITE MUDEL
5.1 Introduction
The Conceptual Site Model (CSM) developed for the site has been used to evaluate the relevant
pathways from the potential sources of contamination identified to points of exposure and the
receptors. It has been developed from information gathered during site investigations carried out
at the manufacturing plant site. The CSM describes all known or potential sources of
contamination, and considers how and where the contamination is likely to move (pathways) and
identifies who or what is most likely to be affected by the contaminants (receptors).
Here the relevant chromium contamination is hexavalent chromium[Cr(VI)] in groundwater and
soil to a much lesser extent trivalent chromium[Cr(lIl)] in the soil. The CSM is shown
diagrammatically in Figure 5.3, and is discussed under the following headings:
• Sources: Primary and secondary sources of contamination
• Transport mechanisms: Pathways
• Receptors: The exposure pathways and other end users who may be impacted by
contaminants in soil or groundwater
5.2 Sources of centamination
5.2.1 Primary sources
The primary source of chromium contamination in the soils and groundwater underlying the
manufacturing plant is considered to be the previous sodium dichromate (SDC) spills during
production and handling at certain locations within the manufacturing plant between 1945 and
1991. It is suspected that the ingress of liquid SDC into the soils and underlying groundwater in
these areas has caused the contamination. The historic activities have lead to high concentrations
of contamination, so called "hot spots", which have subsequently acted as active sources of the
contamination plume that is now observed in aquifers I, 2 and 3. In 1991, the production of
sodium dichromate (SOC) was discontinued on the site, and manufacturing activities were limited
to the manufacture of chromium tanning salts. The production facilities of SDC were closed and
dismantled.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufactunng 7t
plant on a coastal aquifer
5.2.2 Secondary sources
Soil and groundwater sampling was conducted in order to identify the secondary sources at the
site. The highest measured Cr(VI) concentrations in groundwater were found in aquifer I and
aquifer 2 underlying old closed or dismantled production facilities where sodium dichromate
(SDC) liquid was produced or handled between 1945 and 1990 as shown in Figure 5.1. The
highest measured Cr(VI) concentrations in soil samples taken at the manufacturing plant site
coincide with the above mentioned locations. The secondary sources of contamination at the
manufacturing plant site were found to be the following:
• Affected subsurface soil (>0.3m) and
• Dissolved groundwater plume
-3313600-
Turf club site
0
..u IHV
lil>
0 0
1IIl19
0 - -
1HZ IMU 0
... :za
0
IH2>
-3313800- .. t).Hm
&HlA
0• 1
IHZ2lA
ef,a tJ'U
0
SH< ~
0 0IHt6
IHS 0
'IHTI
-3313900- Positions of boreholes 0.uI 0
&HUll ....
o 10, II~bowhoIQ'
o "'217
0
...lJ 0
100 . ~ bOlctToles 0 IIHl!
200 ~botetTob cr- IMIlO
• 200A ser ~ boreh!Hc~ IllIUM
• 300 _il:) bot ehc les (JI>on -e lUl
.400 '. bOfcl1ob ."..
~.HZ1lAO
• D~jco botatlOb ..J
I I
-3900 -3700 -3600
0 lOOm 150m 2DOm 250
Figure 5.1: Suspected hot spot locations based on observed Cr(VI) concentrations in
aquifer 1 and 2.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 79
plant on a coastal aquifer
5.3 Potential transport mechanisms
Having identified secondary sources the next step was to determine the different transport
mechanisms at the manufacturing plant. Based on the results of groundwater sampling (refer to
chapter 4, section 4.6), significant concentrations ofCr(VI) were detected in aquifers I and 2, in
the area underlying the manufacturing plant and neighbouring areas. Cr(VI) was only detected in
aquifer 3, in the limited area underlying the manufacturing plant, immediately above the hippo
mud" clay. In the aquifer below the "hippo mud" clay, especially within the sandstone bedrock
where groundwater is extracted for irrigation at the turf club site, no Cr(VI) was detected.
The results of soil sampling carried out at the manufacturing plant and its surroundings (refer to
chapter 4, section 4.7) indicate that significant concentrations of Cr(lll) and Cr(VI) were detected
in the soils underlying the manufacturing plant. Within the residential area and turf club site, low
levels of Cr(VI) were detected in the soil samples. Thus potential transport media for the
contaminants at the site are soil (through leaching to groundwater) and groundwater (through
dissolved plume migration).
5.4 Exposure pathways
Four possible pathways are defined by the RBCA methodology, i.e soil, air, groundwater and
surface water. The relevant pathways in the study area are air, soil and groundwater.
5.4.1 Air
Air is a potential pathway through inhalation of dust particles containing chromium from possible
wind erosion and atmospheric dispersion of chromium-contaminated surface soils on the site.
However the significance of air pathway in this study is limited due to the fact that most of the
manufacturing plant site is covered in concrete or asphalt, and the residential stands in the area
are small, mostly built up and exposed areas are either concreted or tiled.
Air is also a potential pathway through inhalation of vapours from dissolved chromium plume,
especially where groundwater is used for irrigation e.g groundwater extraction from the Natal
formation is undertaken on the turf club site for irrigation. However, based on the results of site
lnvestigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 80
plant on a coastal aquifer
investigations (refer to chapter 4, section 4.6), no Cr(VI) was detected in samples from pumped
groundwater on the turf club site. Hence the extraction of groundwater from the rock aquifer
revealed no risk at the point of exposure to potential receptors. This pathway was then not
investigated further.
5.4.2 Surface runoff
The majority of the manufacturing plant site is currently paved in concrete or asphalt, and all
surface runoff is collected in surface drains before being discharged into the municipal
stormwater reticulation system. The run-off that is collected in surface drains from the production
area of the site is tested prior to being discharged to the municipal stormwater system. Where the
test results exceed the discharge criteria, the water is pumped into holding tanks and used as
process water in the plant. Hence the present site surface drainage can be ruled out as primary
source for the identified groundwater plume.
5.4.3 Soil
The highest measured chromium concentrations in the soils underlying the manufacturing plant
were found in areas underlying old closed or dismantled production facilities where sodium
dichromate (SDC) liquid was produced or handled between 1945 and 1991. (refer to chapter 4,
section 4.7). It is suspected that the ingress of chromium into the soils from these areas led to the
contamination. Chromium contamination released into the subsurface can work its way down into
groundwater. Therefore the soil properties through which chromium contamination has to pass
through to reach the aquifer play an important role in determining the transport and fate of
chromium contamination. Below is the discussion of some of the soil characteristics.
5.4.3.1 Hydraulic conductivity
Hydraulic conductivity defines the rate of movement of water through a porous medium such as a
soil or aquifer. It is a constant of proportionality in Darcy's law and is defined as the flow volume
per unit cross-sectional area of porous medium under the influence of a unit hydraulic gradient.
Darcyequation:
Q = KiA (Kruseman et al 1991)
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 81
plant on a coastal aquifer
Solving fo K gives,
K=Q/iA
Where:
Q = Volume rate of flow (m3/d)
K = Hydraulic conductivity (mid)
i = Gradient (dimension less)
A = Area (m")
The hydraulic conductivities of the aquifers underlying the manufacturing plant and neighbouring
areas were estimated using grain-size distribution analysis, laboratory tests and borehole pumping
tests (refer to chapter 4, section 4.3). The results of the estimated hydraulic conductivities using
the three methods mentioned above are summarized in Table 5.1 and discussed below.
Table 5.1: Summary of estimated hydraulic conductivities Dlrnaquifers underlying
the_manurfact'uring plant Particle size (%) Average :7;" ~:I1',~;:~" '. " Hydraulic ,Samp Umt Soil type, Soil origi~ , Clay Sill' Sand Gravel" , conductivitY,~ r;;,~~~:;~" , (W1d) '.
BH202 (Im) SAND 8 3 87 2
BH210(3m) Aquiferl SiltySAND 8 5 72 16 1.67
BH209 (4m) SAND 4 2 86 8
BH202(2m) Sandy_CLAY 24 6 70 0
BH201 (5m) Aquitard I Sandy CLAY 29 13 58 0 0.000082
BH204(5m) Sandy CLAY 53 14 33 0
BH204(7m) SAND 8 2 86 4
BH205 (7m) Aquifer 2 SAND 6 8 84 2 0.12
BH202(8m) SAND II 5 81 3
BH204(lOm) Silty Sandy CLAY 23
BH202(lIm) Aquitard 2 Harbour bed
12 65 0
Sandy CLAY sediments 30 II 59 0 0.000097
BH205 (lOm) Sandy Silty CLA Y 31 18 51 0
BH201 (IIm SAND 10 6 81 3
BH203 (Bm Aquifer 3 SiltySAND 10 16 68 5 0.29
BH202(16m SiltySAND 9 22 61 8
BH205 (l2m Silty Sandy CLA Y 21 10 69 0
BH201 (14m Aquitard 3 Sandy CLAY 19 21 60 0 0.000911
BH202(16m SlightlySandy Silly CLA Y 9 22 68 I
BH401 (27m SAND 0 13 81 6
BH403 (27m Aquifer 4 SAND 2 14 84 0 0.02
BHOI (27m) SAND 9 6 85 0
BHD5 (27m) SAND
BH03 (3Om) Sandstone
2 2 95 I
Aquifer SAND Natal Group 6 3 86 5 2.23
BHOI (3lm) SAND 6 0 94 0
Based on the obtained hydraulic conductivities in Table 5.1 above, it is clear that the sandstone
aquifer had higher hydraulic conductivity than the harbour bed sediments which generally occur
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 82
plant on a coastal aquifer
in four predominantly sandy aquifer horizons (aquifers 1,2,3 and 4). This means that the
movement of groundwater in the sandstone aquifer would be faster than in the harbour bed
sediments. Of the harbour bed sediments, aquifer 1 had higher hydraulic conductivity, suggesting
that it would easily transmit water more than the other sandy aquifer horizons (aquifers 2,3 and
4).
The aquitards interlayering different sandy aquifer horizons had very low hydraulic conductivities
and this implies that groundwater movement through these layers would be very slow hence it is
suspected that contamination could diffuse through these layers.
5.4.4 Groundwater
The highest measured Cr(VI) concentrations in groundwater were found in aquifer I and aquifer
2 underlying old closed or dismantled production facilities where sodium dichromate (SDC)
liquid was produced or handled between 1945 and 1991 (refer to chapter 4, section 4.6). The
contaminated groundwater originating from the plant site could migrate into the residential area
and downstream of the plant site, thus posing immediate danger or acute health risk to the
population living in the residential area and downstream of the plant site. The movement of
groundwater and dispersion within the aquifer spreads the contaminant over a wider area, which
can then intersect with groundwater wells, making the water supplies unsafe. Below is the
discussion of some of the groundwater flow characteristics.
5.4.4.1 Groundwater recharge
Durban's climate is characterised by warm humid summers (October to March) during which the
region receives most of it's precipitation. Winters (April to September) are cool and relatively
dry. Average monthly temperatures for the warmest month is 24.6°C (December) and for the
coolest month it is 16.6°C (July). Average annual rainfall is approximately 1000mm.
Due to evaporation and surface runoff the recharge to the groundwater will be lower. The
recharge rate for this area was taken from the Royal Haskoning report (2008) which focused on
the South Durban Basin Area (SDBA), similar to that of the manufacturing plant. According to
the Royal Haskoning report, the study area has a recharge rate of l3% of the mean annual
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 83
plant on a coastal aquifer
precipitation (MAP) using the chloride method. Figures 5.2 below illustrates the minimum and
maximum temperatures and rainfall records for Durban
_Min.Temp -+-Max. Temp ~ Rainfall(mm)
30 180
160
25 140
eu.-.. 20 120
cu
.....
E
::J. 100 E
'.I.). 15 iii
cu 80
Q. -C
.E
.;
c.u. 10 60 cx:
40
5
20
0 r---r 0
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Figure 5.2: Temperatures and rainfall in Durban.
5.4.4.2 Groundwater levels
Groundwater levels (piezometric levels) were monitored in the existing boreholes and new
boreholes put down on the manufacturing plant site and surrounding area on a monthly basis. The
purpose of the groundwater level monitoring was to establish groundwater flow patterns within
the manufacturing plant site and the surrounding area. The recorded groundwater levels in the
boreholes are included in Appendix D, and summarized in Table 5.2 below.
Table 5.2: Summary of measured groundwater levels in the boreholes
Unit Soil type Piezometric level (mbgl)Soil origin Borehole Numbers
Average Range
Aquifer I Sand BH301 to BH318 1.597 o to 3.321
Aquifer 2 Sand Harbour bed BH201A to BH225A 1.248 o to 2.093
Aquifer 3 Sand sediments BH201 to BH225 1.626 o to 3.286
Aquifer 4 Sand BH401, BH402, BH403 2.125 1.361 to 3.474
Sandstone Sand
Aquifer Natal Group 01,03,05 14.322 1.354 to 36.07
mbgl - meters below ground level
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 84
plant on a coastal aquifer
Based on Table 5.2 above, it is evident that shallow groundwater levels occurred at the
approximat depths of 1.2 mbgl and 1.6 mbgl in aquifer 2 and aquifer 1 respectively. Deep
groundwater level occurred at an approximate depth of 14 mbgl in the sandstone aquifer. This
suggests that aquifer I and aquifer 2 could be more vulnerable to hexavalent chromium [Cr(VI)]
contamination through washout of soluble Cr(VI) in the soils by high groundwater table, than
aquifers 3,4 and sandstone aquifer.
Based on the chemical results ofCr(VI) (refer to Appendix E), it is evident that Cr(VI)
concentrations were always higher in aquifer 1 and aquifer 2 as compared to the concentrations of
Cr(VI) in aquifer 3, 4 and sandstone aquifer.
The graphical plots of monitoring data (Figures 4.6 to 4.10) indicate that the groundwater levels
have remained relatively constant throughout the study period of approximately 5 years, and in
most boreholes the groundwater level fluctuations were less than 0.5 meters. This clearly suggests
that the ground water flow could be close to steady state. The graphical plots of monitoring data
also indicate that the notable response in some boreholes could be associated with seasonal
groundwater fluctuations.
5.4.4.3 Groundwater flow directions
Based on the recorded groundwater levels (piezometric levels) in the boreholes (see Appendix D),
the standing water elevations were determined. It was assumed that the groundwater level
distribution generally emulates the surface topography and therefore the contaminated
groundwater would flow from a topographic high to a topographic low. The Bayesian
interpolation technique, which uses the possible relationship between the topography and
groundwater levels, was used to interpolate groundwater levels and therefore the groundwater
flow directions.
The groundwater level contour plots (Figures 4.12 to 4.16) indicate that the direction of
groundwater flow in aquifers 1 to 3 was from the west to the east. Within Aquifer 4 and the
sandstone formation the groundwater flow was from the north west to the south east in principle
corresponding to the regional groundwater flow at depth from the hills towards the sea.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 85
plant on a coastal aquifer
5.4.4.4 Seepage velocity
The movement of water through a soil mass is generally termed seepage. On a microscopic scale
the water when flowing follows a tortuous route through the voids in the soil. From a practical
point of view, however, it is assumed to follow a straight-line path. In Darcy's equation, the
velocity v is interpreted as the apparent or superficial velocity i.e the velocity of flow relative to a
soil section area A. The actual velocity through pores will be greater, and this is termed seepage
velocity (vs).
Seepage velocity: Vs= Q/nA = Kiln (Kruseman et al 1991)
Where:
Q = volume rate of flow (m3/d)
n = porosity (dimensionless)
A = Area (rrr')
K = Hydraulic conductivity (mid)
i = Gradient
The equation mentioned above was used to calculate the seepage velocities using the available
hydraulic conductivity, hydraulic gradient and porosity data from field investigations (refer to
chapter 4, section 4.3). The results are presented in Table 5.3 below.
Table 5.3: Summary of estimated seepage velocities for aquifers underlying the
manufacturing plant
1.67 0.0159 0.306 0.0864
0.12 0.0173 0.261 0.0079
Harbour bed
sediments
0.29 0.0443 0.257 0.0501
0.02 0.0084 0.287 0.0006
Sandstone
Aquifer Natal Group 2.23 0.0068 0.386 0.0391
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 86
plant on a coastal aquifer
Based on the obtained seepage velocities in Table 5.3 above, it is clear that the harbour bed
sediments which occur in four predominantly sandy aquifer horizons (aquifers 1,2,3 and 4)
generally had higher seepage velocities than the sandstone aquifer. This means that the rate of
movement of Cr(VI) in harbour bed sediments would be faster than in the sandstone aquifer. Of
the harbour bed sediments, aquifer 1 and aquifer 3 had higher seepage velocities than aquifers 2
and 4. This suggests that the rate of movement ofCr(VI) in aquiferl and aquifer 3 would be faster
than in the other sandy aquifer horizons (aquifers 2 and 4).
Assuming a cross-section of lOOmlength, the travel times for Cr(VI) in various aquifers
underlying the manufacturing plant were approximated. According to the results presented above
it would take 1157days for Cr(Vl) to travel through 100m of aquifer 1, 1996 days in aquifer 3,
2558 days in sandstone aquifer, 12592 days in aquifer 2 and 169237 in aquifer 4.
Based on the chemical results ofCr(Vl) (refer to Appendix E), it is evident that Cr(VI)
concentrations were always higher in aquifer 1 and aquifer 2 as compared to the concentrations of
Cr(V1) in aquifer 3, 4 and sandstone aquifer. However, the observed high Cr(VI) concentrations
in aquifers 1 and 2 could not be determined whether it was due to the rate of movement (seepage
velocities) of chromium-contaminated groundwater in the sandy materials.
5.4.4.5 Retardation
If contaminants undergo chemical reactions while being transported through an aquifer, their
movement rate may be less than the average groundwater flow rate, this effect is called
Retardation (Palmer, 1989a). Such chemical reactions that slow movement of contaminants in an
aquifer include sorption (i.e. adsorption, and ion exchange). Adsorption includes the processes by
which a solute clings to a solid. Iron exchange is when the cation/anion are attracted to the region
close to a positively/negatively charged clay-minerals surface and held there by electrostatic
forces.
Retardation is simply the ratio of the velocity of a dissolved contaminant plume in relation to the
bulk velocity of the groundwater. It can be described by the conventional retardation equation
(Lyman et al., 1992):
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 87
plant on a coastal aquifer
Where:
Rf = retardation factor (dimensionless)
Vw = the average velocity of water (cm/sec)
Vc = the average velocity of chemical contaminant (cm/sec)
Kt= distribution coefficient (crrr'zg)
Pb = bulk density of the aquifer (g/crrr')
n = soil porosity (dimensionless)
The equation mentioned above was used to estimate Cr(Vl) retardation factors using the available
data from field investigations (refer to chapter 4, section 4.3). The results are presented in Table
5.1 below.
Table 5.4: Estimated retardation factors for hexavalent chromium [Cr(VI)]
SAND 6.32
Sit SAND 6.35 1.52 19 0.306 lOO
SAND 6.42
SAND 7.08
Aquifer 2 SAND 12.16 1.52 17 0.261 102
SAND Harbour bed 6.32
SAND sediments 6.71
Aquifer 3 Sil SAND 6.21 1.52 19 0.257 114
Sil SAND 6.32
SAND 6.24
Aquifer4 SAND 6.02 1.52 19 0.287 102
SAND 7.74
SAND 6.78
Sandstone
Aquifer SAND Natal Group 7.05 1.52 19 0.386 77
SAND 7.74
According to the results presented in Table 5.4 above, it is evident that the harbour bed sediments
which occur in four predominantly sandy aquifer horizons (aquifers 1,2,3 and 4) had higher
retardation factors than the sandstone aquifer. This implies that Cr(VI) would be adsorbed more
in the sandy materials (aquifers 1,2,3 and 4) than in the sandstone aquifer. This suggests that the
sandstone aquifer is expected to have high concentrations ofCr(VI) as compared to the sandy
materials (aquifers 1,2,3 and 4) .
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 88
plant on a coastal aquifer
Based on the chemical results of Cr(VI) in Appendix E, it is evident that Cr(VI) concentrations
were always higher in aquifer I and aquifer 2 as compared to the concentrations ofCr(VI) in
aquifer 3 and aquifer 4. Within the sandstone bedrock where groundwater is extracted for
irrigation at the turf club site, no Cr(VI) was detected. Clearly the estimated retardation factors
were found to be not consistent with the chemical results, indicating that chromium
contamination could not be explained by retardation process only.
5.4.5 Potential receptors and complete pathways
Based on the results of the field investigations (refer to chapter 4, sections 4.6 and 4.7),
The following potential exposure pathways of contamination from the source to the point of
exposure and receptors have been identified in the study area.
e Soil to human - Is the potential exposure of humans by ingestion, dermal contact or
inhalation of Cr(VI) or Cr(IlI) of contaminated soil. For inhalation, exposure is via the
top 30cm of soil. For ingestion and dermal contact, exposure is via the top 60cm of soil.
• Soil to groundwater - The receptor or subject of protection is the groundwater with the
point of exposure at the groundwater surface.
• Soil to plant - Concerns the potential uptake of Cr(VI) by the plants from contaminated
soil/groundwater.
• Groundwater - Is the migration of the Cr(VI) contamination within the groundwater to
any receptor. It is addressed in this context as groundwater plume or plume only.
• Groundwater to construction worker - Addresses the potential exposure of construction
workers by dermal contact and involuntarily ingestion of contaminated groundwater
during below ground level construction work.
• Groundwater to shallow boreholes - Addresses the potential exposure of receptors by
groundwater extracted for use from shallow aquifers above the Hippo Mud. Potential
receptors could be humans (drinking water), livestock or plants (irrigation).
ct Groundwater to deep boreholes - Addresses the potential exposure of receptors by
groundwater extracted for use from the fractured rock aquifer (Natal Sandstone
formation) below the Hippo Mud. Potential receptors could be humans (drinking water),
livestock or plants (irrigation).
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 89
plant on a coastal aquifer
The identified exposure scenarios and potential pathways of the contaminant from the source to
the point of exposure of the receptors are shown diagramatically in Figure 5.3 below.
Site Neighbouring Areas
···.·.·.·.·.·.·..·...·.·..'0
CD @ GroundwaterSoil - Human
@ ® Groundwater - Construction SiteSoil - Groundwater
<y @ Groundwater - Groundwater WellSoil - Plant I Fruit (!) Deep Groundwater - Groundwater Well
Figure 5.3: Sources, pathways, exposure scenarios and receptors of concern at the
manufacturing plant site.
lnvestigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 90
plant on a coastal aquifer
CHAPTER 6. RISK ASSESSMENT
6.1 Risk Based Corrective Action
6.1.1 Overview of Risk Based Corrective Action
Risk Based Corrective Action (RBCA) is a decision-making process for assessment and response
to subsurface contamination associated with chemical substance releases. The guidelines for
RBCA are published in American Society for Testing Materials (ASTM E-1739-95). RBCA
integrates Environmental Protection Act (EPA) risk assessment practices with traditional site
investigation and remedy selection activities in order to determine the cost-effective measures for
protection of human health and environmental measures. Under this integrated approach,
chemical substance release sites are characterized in terms of sources, transport mechanism and
receptors. Remedial measures are then applied as needed to human health or environmental
exposure to harmful levels of site constituent. Risk Based Corrective Action can be used by
addressing any step in the exposure process such as (Connor et aI, 1995):
1. Removing or treating the source
II. Interrupting contaminant transport mechanism or
Ill. Controlling activities at the point of exposure.
Under RBCA, risk management strategies are developed and implemented in accordance with the
process flowchart as shown in Figure 6.1 below. Based on the available site information, a site
classification step is completed to characterize the relative magnitude immediacy of site risks and
prescribe immediate response actions (Step 2 on figure 5.2). After any acute or near-term hazards
have been properly addressed, risk-based clean-up standards are developed to protect against
potential chronic health or environmental impacts associated with long-term exposure to low
levels of contaminants (Step 3-7 on figure 5.2). To achieve the final risk management goals, the
remedial action program may involve:
I. Source removal/treatment
Il. Contaminant measures
lil. Institutional controls and
IV. Some combination thereof.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 91
plant on a coastal aquifer
Initial Site Assessment
Coodu<! Site Inve<lli9ation and compIe!e ~ 1 Sull1r1l31Y RE9O!t Il) OlO'lnir.e
3'J3Dallle sr.e i11omlllllon reo3J1llng pnnCip.a1contaminants, pres~nce of atreete<l
envlrcm18rml nleda, and pcIalIiaI mÓJralan paJ1~ and ret:.epWe.
Site Classification and Initial Response Action Interim Corrective Action
ClaSsify- IlIIe perspedfted seenanos Implemerrt approjlnate inbaJ response acoon. CoodUCl patiaJ sourc,;;
ReclasSify ste a~ a~nate (olowiJ19 1niti31and intem1 resporae actions cr rerrova or 001er acton iD
a~iO!}f1;J]Oata C1l!1eC!ian. reduce risk{~) and adjJst
Ili1s d:lSSiflcalioo.
Tier 1Evaluation
Idenary rsa!10113ll1!; pc<ef\:ial soc.rc:es, transport J)a!I;W3'/S, and inr.iaJ response aaioo.
ReclasSi~1sr" 3!) apprnpf13te rolov.inQ il'iO;1i,ml in:ertm roopons,;;actions 3ild:Oona
aam OlIleaion.
-----,
lier 3 Evaluations
C(>Ilectaddi~ona Ili1sdala 3!)ne,;;~.
Coodu<! TIer :1 asse5S1l1em per sp,;;áfied proceduR!s. C001p.areTP-f 3 Site-Spet'.ffic I
Target(S9TlA) 'l,itlllli!e coroiti0n9. ___I
Remedial Action Program
Ide11Ury I!CI!It-etreC!ivemeans of acnlevi1g nnal COITeC!i',,;; acoans ~s, Indud~
con1Ji1lTioro of rsmedia:ion, natLr.ll at!ei1UlTion, and irotillItional contrOls.
ImPlemern me prel,;;rre,J aternative.
Comptlance monitoring
Coodu<! mol'irm1rt9 progr,nn a~ needed to commi lIlat COlTeetr<e action gooI~
are saOOfied.
Figure 6.1: ASTM Risk-Based Corrective Action (RBCA) flowchart (Connor et al,
1995).
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 92
plant on a coastal aquifer
Further discussion of the underlying concepts of the RBCA process, as well as the specific tasks
involved in site classification and development of risk-based remediation goals are provided
below.
6.1.2. Hazard ebaracterization and response under RBCA.
Release of petroleum products or other chemical substances can result in an acute (i.e. ,
immediate) or a chronic (i.e. , long-term) hazard to life or health. In general, chronic hazards are
associated with long-term exposure to relatively low levels of the site constituents, whereas acute
hazards involve high concentrations sufficient to pose an immediate risk of fire, explosion, or
health impairment. The presence of an acute hazard can be ascertained based on established
threshold criteria (e.g. , lower explosive limit, vapour lDLH). However, chronic health effects are
not immediately evident and therefore require a more careful evaluation of long-term, future
exposure patterns in order to establish appropriate site cleanup (Connor et ai, 1995).
Consistent with EPA risk assessment protocol, the RBCA Tier I, 2, and 3 evaluations address
source zone cleanup standards that will protect against chronic health or environmental impacts,
i.e. , carcinogenic or toxic effects caused by long-term exposure to low level of contaminants.
Such analysis is appropriate only after any and all acute hazards associated with the site have
been identified and properly controlled. For this purpose, the RBCA evaluation process requires
site classification and implementation of appropriate interim response actions (see step 2 on
Figure 6.1) prior to analysis of media cleanup standards. Types of acute hazards to be addressed
in the site classification-response phase include explosive vapour levels, utility impacts, or the
presence of free phase hydrocarbon liquid in the groundwater. In addition, interim stabilization
measure may be applied to prevent incidence of short-term chronic impacts.
Following completion of step 1 to 4 ofRBCA process (Figure 6.1), the procedures outlined in
this ASTM Risk Based Corrective Action can be used to define site-specific soil and groundwater
cleanup levels necessary to protect against future health impacts. The general sequence of hazard
characterization and response under RBCA is illustrated on Figure 6.1. As shown, in some
applications, other non-aesthetic consideration (i.e. , odour, appearance and taste) may affect the
future use of a property or resources even after constituent concentrations have been reduced to
levels posing no further health concern (Con nor et ai, 1995).
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 93
plant on a coastal aquifer
6.1.3 RBCA Site Classification
Under the RBCA planning process, sites are first classified with regard to the current magnitude
and immediacy of human health and environmental risks. Appropriate emergency actions are then
implemented without delay to address acute hazards or near term-term impacts. Under the
classification scheme outlined in ASTM E-1739, applicable exposure scenarios are reviewed to
match the site with one of the four qualitative risk categories indicated in Table 6.1 below. For
each classification, an appropriate response action is prescribed to effectively manage the
potential site hazards as the site evaluation and remediation process. As shown on Table 6.1,
remedial actions are expected at near-term high-risk sites, while interim monitoring systems are
required to long-term, low-risk sites. This site classification represents a "snapshot" in time,
addressing hazards associated with current site conditions and land use.
Table 6.1: RBCA site classification and response actions (Connor et al, 1995)
Current Hazard Site Classification Initial Response Action
Acute Class 1: Immediate threat Abate release
Chronic Class 2: Near-term threat MonitorlRemediate
(O-2years)
Class 3: Future threat Monitor/Investigate
(>2years)
Aesthetic Class 4: No current Monitor only
demonstrate risk
6.1.4. Tiered Evaluation of Risk-Based Standards
To address the chronic human health or environmental hazards, site remediation requirements are
evaluated on the basis of risk-based soil and groundwater cleanup goals, developed in accordance
with U.S.EPA risk assessment guidelines. To provide an economical use at both small and large
facilities, the RBCA process has been designed to match the site evaluation effort to the relative
risk or complexity of each site. For this purpose, a tiered approach is employed for determination
of risk-based cleanup goals, involving increasingly sophisticated levels of data collection and
analysis. Upon completion of each sequential tier, the user reviews the results to determine
whether further data collection and evaluation is warranted. For purpose of efficiency, the site
investigation steps and decisions involved in this process are indicated on the RBCA flowchart
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 94
plant on a coastal aquifer
(Figure 6.1). The scope of Tiers 1, 2, and 3 are as follows (Connors et al, 1995):
6.1.4.1. Tier 1: Generic Screening-Level Corrective Action Goals
Tier I of the RBCA process involves comparison of site constituent concentration to generic Risk
Based Screening Levels (RBSLs) to determine whether further evaluation is required. RBSL
values are derived from standard exposure equations and reasonable maximum exposure (RME)
estimates per U.S.EPA guidelines. RBSL concentration limits are designed to be protective of
human health even if exposure occurs directly within the on-site area of affected soil or
groundwater (i.e., the source zone).
If Tier 1 limits are not exceeded, the user may proceed directly to compliance monitoring and/or
no further action (see Figure 6.1). However, if these generic levels are exceeded, the affected
media may be addressed by:
I. Remediating the generic Tier I limits, ifapplicable
II. Conducting a Tier 2 evaluation to develop site-specific remediation goals
Ill. Implementing an interim action to abate risk "hotspots".
In general, the Tier I evaluation serves to identify sites requiring no further action. For most sites
exceeding Tier I limits, a Tier 2 analysis will provide a more cost-efficient basis for evaluation of
appropriate remedial measures.
6.1.4.2. Tier 2: Site-Specific Corrective Action Goals
Under Tier 2, Site-Specific Target Levels (SSTLs) for soil and groundwater cleanup goals are
determined on the basis of site-specific information and/or points of exposure. Simple analytical
models are employed in conjunction with additional site data to calculate Tier 2 SSTL values in a
manner consistent with EPA-recommended practices. Modelling and calculation procedures are
streamlined so as to represent a minor incremental effort relative to Tier I.Both the Tier I RBSL
and Tier 2 SSTL values represent concentration limits for constituents within the source zone.
However, SSTLs differ from RBSLs in three significant ways:
I. Site-specific data are used to calculate the risk-based cleanup goals
II. Human exposure to affected media may be assumed to occur not at the source zone, but
at the separate "point of exposure" (POE) ani
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 95
plant on a coastal aquifer
The effects of natural attenuation of constituent concentration during lateral transport from the
source to an off-site POE may be considered in the SSTL calculation (Figure 5.3).
If site constituent concentrations exceed SSTL values, subsequent actions may involve the
following:
1. Remediation to site-specific Tier 2 cleanup goals
11. Further evaluation per Tier 3 of the RBCA process
111. Interim response measures targeted at principal risk sources (see Step 6 on Figure 6.1)
6.1.4.3. Tier 3: Site-Specific Corrective Goals
If Tier 2 results are judged inappropriate or impracticable, a Tier 3 evaluation can be conducted
to refine Tier 2 corrective action goals on the basis of a more complex risk and exposure
assessment, involving more detailed site information, probabilistic data analysis, and/or
numerical fate and transport modelling. Such Tier 3 evaluation will typically entail significant
additional data and expense relative to Tiers 1 and 2 should therefore be reserved for highly
complex, cost-significant sites. Tier analysis may be warranted at sites for which Tier 2
modeling methods are non-conservative or detailed ecological impact assessment are required.
Similar to Tier 2, the Tier 3 evaluation provides source zone cleanup levels designed to protect
against health or environmental impacts at a site-specific POE . The tiered evaluation process
concludes upon derivation of applicable and remediation standards. It should be noted that the
soil and groundwater standards developed under Tier 1, 2, and 3 are equally protective of human
health and the environment, based on applicable target risks and exposure criteria. However,
with each tier upgrade, the degree of uncertainty and conservation involved in the cleanup
standard calculation is reduced based upon a more detailed characterization of actual site
condition. As indicated on the RBCA process flowchart (Figure 6.1), the user reviews the results
of each tier to determine if further evaluation is necessary (Connor et ai, 1995).
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 96
plant on a coastal aquifer
6.2 Tier 1 evaluation: Generic screening-level corrective action goals
6.2.1 Introduction
In the course of the Tier 1 risk assessment the potential pathways and exposure scenarios
identified by the Conceptual Site Model (CSM) were evaluated. The identified potential pathways
and exposure scenarios are summarised in Table 6.2 and discussed below.
Table 6.2: Exposure pathways and scenarios identified by CSM
Exposure pathway Exposure scenario
Soil to human
Soil Soil to groundwater
Soil to plant
Groundwater to construction worker
Groundwater Groundwater to shallow boreholes
Groundwater to deep boreholes
The Tier I evaluation was done by comparing the detected contamination at the point of exposure
with internationally accepted general risk-based screening levels (RBSLs). Screening levels are
conservative concentrations below which an exposure would not pose a health risk to the most
sensitive exposed receptor. Where contaminant concentrations are below screening levels, no
corrective actions are required.
If concentrations at the point of exposure exceed screening levels, the receptors might be exposed
to an unacceptable risk. In such a case a detailed risk assessment (Tier 2) for the site specific
exposure/receptor relationship is needed to quantify the actual risk or corrective, mitigation or
remediation actions which are necessary. Furthermore, if general screening levels do not exist or
if they are not appropriate/applicable for the situation at hand, pathway and receptor specific risk
assessments are carried out to assess the actual risk and to deduce appropriate actions.
6.2.2 Soil to human
Most of the manufacturing plant site is covered in concrete or asphalt. However, the possibility
that workers could come in contact with the impacted subsurface soils on the plant site at non-
sealed surfaces cannot be ruled out completely. That scenario could cause a risk of inhalation of
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 97
plant on a coastal aquifer
dust particles containing chromium or ingestion of chromium contaminated soils with concurrent
skin contact.
The residential stands in the area are small, mostly built up and exposed areas are either concreted
or tiled. However, the possibility that the general public could come in contact with the impacted
subsurface soils in the residential area at non-sealed surfaces cannot be ruled out completely. That
scenario could cause a risk of inhalation of dust particles containing chromium or ingestion of
chromium contaminated soils with concurrent skin contact.
The Tier I risk assessment for the exposure scenario soil to human considered exposures to
Cr(lII) and Cr(VI). The risk was assessed by comparing the soil contamination with the
appropriate soil screening levels (SSL).Generally, inhalation, ingestion and dermal contact are
considered relevant routes of exposure for soil at all depths. Inhalation is only regarded as a
relevant route of exposure for near surface soils at depths of less than 30 cm below ground level.
The analytical results for Cr(VI) and Cr(lII) were compared to the US EPA soil screening levels
for Cr(VI) and Cr(III) as listed in Table 6.3. The results of the risk assessment for the exposure
scenario soil to human are given in Appendix G and discussed below.
Table 6.3: US EP A Generic Soil Screening Levels
Residential Scenario CommerciallIndustrial Scenario:
Outdoor Worker Receptor
Compound Ingestion Inhalation of Ingestion! Inhalation of/Dermal Fugitive Dermal Fugitive
(mg/kg) Particulates (Dlg/kg) Particulates
(m2lke> -. (melke)
Trivalent Chromium
c-rnn 120000
Low toxicity; no 1000000 Low toxicity; noguideline guideline
Hexavalent Chromium
Cr (VI) 230 260 3400 510
Based on the results of the risk assessment for the exposure scenario soil to human in Appendix
G, it is evident that the measured concentrations both for Cr(Ul) and Cr(VI) in the soil samples
taken on the manufacturing plant site were always below the SSL's for ingestion and dermal
contact for commercial/industrial areas. Beneath certain areas of the plant site, the Cr(VJ)
concentrations in the soil exceeded the SSL's for inhalation of fugitive particulates. These
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 98
plant on a coastal aquifer
contaminant values do not pose a health risk to workers on the plant site or on neighbouring
industrial sites, as in all instances the ground surface is covered by buildings and/or paved in
concrete/asphalt. Special safe working procedures should be established and applied where
infrequent excavations on the plant site are required. Further corrective actions concerning the
potential exposure of workers to soil on the plant site are not deemed necessary. In Figure 6.2 the
maximum measured Cr(VI) concentrations in the soil samples taken on manufacturing plant site
are visualized.
....
Turf club site
-3313700-
o • m
o.
o lPl8Tnt n lP" n
-3313800- TP Jó ,rin' 0 'r'P1s
Tno
mP o
OTl'lI
"'''0 ")6 0 rE
Tl'JS l'P40
TI'
-3313900-
Cr(VI) [mg/kg)
0<0.02 < detection li II)
o 0.02toS < SSL(lnh lalIGn)
• SJOt034OO < SSL(Ingestion/dermal)
• >3 ~ SSL(I eston/dermal]
I
-3900 -3800
Om
Figure 6.2: Maximum Cr(VI) concentrations in the top soil on the manufacturing
plant.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 99
plant on a coastal aquifer
ln Figure 6.3 the maximum measured Cr(III) concentrations in the soil samples taken on
the manufacturing plant site are shown.
-3313600-
N
A
Turf club site
0
lPlIO
o 0
0
1'26
o lP"Tm .J0;J-3313800- mi Th} Q5
'Q TI'3O
o 00Ef 927 0
mP 0
ma OmafPS
lP,kJ 0 rPM 0 0
lP)"cP TI'U Po r_
lPn
lP7 0 lPP lP40
JJ
bJ 0 rhJlP14
lP 0
-3313900 15 0 01NJ lP42
Cr(lIl} [mg/kg) '-op06m)
0<0.02
00.0 to 00000o
• >1000000
-3900
Clm lS0m
Figure 6.3: Maximum Cr(III) concentrations in the top soil on the manufacturing
plant.
The measured concentrations of Cr (Vr) in the upper 30cm of soil in the residential area and turf
club site were much lower than SSL's for inhalation as well as ingestion/dermal contact of 260
mg/kg and 230 mg/kg respectively. Similarly, the concentrations ofCr(VI) in the unsaturated
soils at greater depths were below the SSL's for ingestion and dermal contact. The majority of the
soil samples in the residential area and turf club site reported Cr (VI) concentrations at levels
below the method detection limit ofO,02mg/kg.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 100
plant on a coastal aquifer
All deduced Cr(lII) concentrations of the soil samples were well below the SSL of 120000 mg/kg
in the neighbouring area. Hence neither of the concentrations ofCr(V1) and Cr(III) found in the
soils of the neighbouring area pose risk to humans.
Figure 6.4 gives an overview of the maximum measured Cr(VI) concentrations in the soil
samples outside of the manufacturing plant site in the top 60 cm.
-nl3600-
lol
A
Turf club site
-3313800-
-3313900-
Residential
I I
-3700 -3600
lS0m
Figure 6.4: Maximum Cr(VI) concentrations in the top soil off the manufacturing
plant.
Lnvestigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 101
plant on a coastal aquifer
In Figure 6.5 the maximum measured Cr(III) concentrations in the soil samples off the
manufacturing plant site in the top 60 cm are shown.
-3313600-
lol
A
Turf club site
-3313700-
-331.3800- 0SJ
0
S4
0
S7
-3313900-
I
-3900 -3600
Om lS0m 200 2SOm
Figure 6.5: Maximum Cr(III) concentrations in the top soil off the manufacturing
plant.
6.2.3 Soil to groundwater
The highest measured chromium concentrations in the soils underlying the manufacturing plant
were found in areas underlying old closed or dismantled production facilities where sodium
dichromate (SDC) liquid was produced or handled between 1945 and 1990. (refer to chapter 4,
section 4.6). Besides the 'hot spots' (active sources), the site investigations revealed Cr(VI)
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 102
plant on a coastal aquifer
concentrations in the soil on parts of the manufacturing plant site and at some locations in the
neighbouring area.
It is suspected that the ingress of chromium into the soils from these areas led to the
contamination. Chromium contamination released into the subsurface can work its way down into
groundwater. This exposure pathway indicates whether an established soil contamination poses a
risk to the groundwater as a protected natural resource. The contaminant of concern for this
pathway is Cr(VI) only. Cr(lII) need not be considered due to its low solubility in water and its
general transport behaviour in groundwater.
It is believed Cr(VI) containing process residuals were used in the past for backfilling on the
manufacturing plant site. This might be an additional limited source for groundwater
contamination through washout of soluble Cr(VI) by infiltrating rain or high groundwater table.
However, the observed high Cr(VI) concentrations in aquifers 1 and 2 cannot be explained by the
latter processes only.
To assess the risk of soil contamination, US EPA generic soil screening levels for the migration
to ground water were applied as shown in Table 6.4. The results of the risk assessment for the
exposure scenario soil to groundwater are given in Appendix G and discussed below.
Table 6.4: US EPA generic soil screening levels for migration to groundwater
Migration to Migration to
Compound eroundwater eroundwaterDAF=20 DAF=l
< (mwk2) (mwk2)
Trivalent Chromium Cr (III) No concern No concern
Hexavalent Chromium Cr (VI) 38 2
DAF: Dilution Attenuation Factor
Based on the results of the risk assessment for the exposure scenario soil to groundwater in
Appendix G, it is evident that on the manufacturing plant site outside the groundwater plume
area, the Cr(VI) concentrations in the soils were below the SL of38 mg/kg. In the vicinity of the
'hot spots' the Cr(VI) concentrations were above the SLoTherefore these contaminated soil areas
have an impact on the groundwater plume. It is therefore considered a priority to take measures
that would further reduce the possibility of contact with the contaminated ground water and to
implement a strategy of corrective action to reduce the levels of contamination. Members of the
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 103
plant on a coastal aquifer
community should be made aware that deep excavations into the plume area should be avoided.
Corrective action concerning the groundwater plume is necessary
In the residential area and turf club site, the measured Cr(VI) concentrations in the soil samples
outside the plume area and within the plume were all below the SL of38 mg/kg. Hence the
migration ofCr(VI) from the soil to the groundwater in the neighbouring area is of no concern
and does not pose a risk. Figure 6.6 shows the maximum measured Cr(VI) concentrations in soil
samples on and off the manufacturing plant site.
-3313600-
lol
A
Turf club site
0
SI
0
$1
,..•.
!'1•7 wW ,.IIIs
-3313800- . 0TI'3O· S3."JI • ,.•ll,. lP)6 0
TP« 0
lPlS 11•'«1 W
lP
T&1 0S7
-33B900 TP• 0.J lP
0
SlO
Cr(VI) [mg/kg) tTop 0 Gm)
oo <0.02 < det non li t0.02 to~ < SSL(OAFal)
.2to Il <SSL(OAfa20)
• >38 > SSL(OAf 20)
I I I
-3900 -3800 -3700 -3600
Om SOm 100 lSOm 200 2SOm
Figure 6.6: Maximum Cr(VI) concentrations in the top soil on the manufacturing
plant.
lnvestigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 104
plant on a coastal aquifer
6.2.4 Soil to plant
The potential pathway of Cr(VI) from soil (and groundwater) to plants is of concern to the
residents of the neighbouring residential area adjacent to the manufacturing plant. Numerous
studies and scientific papers, i.e. Lytle et. al. 1998 or Zayed & Terry, 2003, clearly indicated that
the soluble Cr(VI) is not taken up easily by plants. Iftaken up by plants or in general by living
tissue it is rapidly converted to Cr(III). Cr(III) in plants does not pose any risk to human health
since it is an important component of a balanced human diet. Hence the exposure scenario soil to
plant to human does not pose a risk.
6.2.5 Groundwater plume
Based on the site investigation results (refer to chapter 4, section 4.6) the extent of the Cr(VI)
plume is well documented in aquifers 1,2 and 3. In aquifer 4 and within the underlying fractured
rock aquifer of the Natal Sandstone formation no Cr(VI) was detected. The main portion of the
actual plume is located within aquifer I and aquifer 2 where the maximum Cr(VI) concentrations
were observed. In aquifer 3, Cr(VI) was detected within a limited area at the manufacturing plant
site. In aquifer 4 and within the Natal Sandstone formation, where groundwater is extracted for
irrigation at the adjacent turf club site, no Cr(VI) was detected. Figure 6.7 shows the projected
extent of the Cr(VI) plume. Outside this area all the analysed Cr(VI) concentrations of the
groundwater samples were below the detection level ofO.02 mg/l,
To assess the risk of groundwater contamination in terms of the potential use of the groundwater
in the area, the analytical results for Cr(VI) were compared to the generally accepted Tier 1 risk-
based screening levels (RBSLs) for Cr(VI) in groundwater as shown in Table 6.5 . The results of
the risk assessment for the groundwater contamination are given in Appendix G and discussed
below
Table 6.5: US EP A risk based screening levels for groundwater
Hexavalent Chromium Cr
(VI) 0.05 0.1 1.0
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 105
plant on a coastal aquifer
Based on the results of the risk assessment for the groundwater contamination in Appendix G, it
is clear that the amount of the Cr(VI) concentrations in the groundwater plume exceeded all risk
based screening levels for drinking water, irrigation and livestock. The groundwater within the
plume is not fit for any use. It should be appreciated that the contaminated groundwater starts
approximately 1 to 2 meters below the ground surface. Provided a person does not come into
direct contact with the contaminated water, for example through drinking or skin contact, there
would be no risk of adverse health effects to the person. The contaminated groundwater is clearly
not suitable for drinking, irrigation and livestock, as exposure to large quantities of the
contamination could lead to serious health effects.
It is therefore considered a priority to take measures that would further reduce the possibility of
contact with the contaminated groundwater and to implement a strategy of corrective action to
reduce the levels of contamination. Members of the community should be made aware that deep
excavations into the plume area should be avoided. Corrective action concerning the groundwater
plume is necessary.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 106
plant on a coastal aquifer
-3313600-
N
A
Turf club site
-3313700-
-3313800-
o
IHU
-3313900- Cr(VI) [mg/I]
o <0.02
00.021 10
10 to 100
.10010 0
.100010
• >10000 Residential
I I I
-3900 -3800 -3700 -3600
Om 250m
Figure 6.7: Projected extent of plume.
6.2.5.1 Excavation Works
The groundwater within the plume is not fit for any use (refer to section 6.2.5). It should be
appreciated that the contaminated groundwater starts approximately I to 2 meters below the
ground surface. Any excavations and below ground level construction within the plume area
would potentially expose workers and members of the public to dermal contact with the
contaminated groundwater.
Therefore in a scenario of dermal contact with small quantities of contaminated groundwater with
concurrent ingestion, slight adverse systemic health effects may be possible, e.g. various degrees
of gastrointestinal effects, depending on the chromium concentration and volume ingested, as
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 107
plant on a coastal aquifer
well as the sensitivity of the exposed individual. Dermal allergic reactions, as well as dermatitis,
may be observed in chromium sensitive individuals exposed to chromium in the groundwater,
especially where levels of contamination are high.
Appropriate work procedures should be developed and applied during all future excavations and
below ground level construction within the plume area. These procedures should comprise
protective and safety measures to prevent worker exposure to the Cr(VI) contaminated
groundwater.
6.2.5.2 Groundwater extraction from shallow boreholes
Based on the results of the hydrocensus, it was revealed that there was no groundwater extraction
from the shallow boreholes on the manufacturing plant and the neighbouring areas. Hence the
potential exposure pathway does not exist and currently poses no risk to potential
receptors.Groundwater extraction boreholes or wells must not be installed within the plume area
except for remedial actions. The Department of Water Affairs and Forestry should be requested
to assist in this regard by applying the necessary controls.
6.2.5.3 Groundwater extraction from deep boreholes
Based on the results of the hydrocensus, it was revealed that groundwater extraction from the
deep fractured rock aquifer was being undertaken on the turf club site for irrigation. The use of
groundwater for irrigation purposes would create the possibility that humans come into contact
with Cr(VI) - contaminated groundwater. The most likely exposure route would be dermal
contact or accidental ingestion.However, based on the results of the site investigations (refer to
chapter 4, section 4.6), no Cr(VI) was detected in samples from pumped groundwater on the turf
club site. Hence the extraction of ground water from the rock aquifer revealed no risk at the point
of exposure to potential receptors.lt is recommended to regularly monitor the extracted
groundwater on the turf club site.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 108
plant on a coastal aquifer
CHAPTER 7. CONCLUSIONS AND RECOMMENDATIONS
7.1 Conclusions
Based on the theoretical research the following conclusions can be made:
e Chromium is an important industrial metal used in diverse processes. At many industrial
and waste disposal locations, chromium has been released to the environment via leakage
and poor storage during manufacturing or improper disposal practices
e In the environment, chromium is commonly found in two most stable oxidation states as
trivalent chromium [Cr(IlI)] and hexavalent chromium [Cr(VI)], each characterized by
distinctly different chemical properties, bioavailability, and toxicity.
o Trivalent chromium is an essential element for living beings, has relatively low toxicity,
immobile under moderately alkaline to slightly acidic conditions, and strongly partitioned
into the solid phases, while hexavalent chromium is very toxic, carcinogenic, and
mutagenic to both animals and humans. It is also very soluble, mobile, and moves at a
rate essentially the same as the groundwater (Palmer and Puis, 1994). Industrial
applications most commonly use chromium in the Cr(VI) form, which can introduce high
concentrations of oxidized chromium (chromate) into the environment.
Based on the results of the case study the following conclusions can be made:
• An investigation was initiated in the study area following the discovery of hexavalent
chromium in groundwater. Hexavalent chromium was detected in groundwater, in an
open pit just outside the perimeter of the manufacturing plant. The historical source of
this chromium contamination in the groundwater is considered to be the old sodium
dichromate production and handling areas. It is suspected that the ingress of chromium
into the soils from these areas led to the contamination.
Cl A hydrocensus survey was conducted in a 1 km radius of the manufacturing plant site in
order to establish if any groundwater extraction boreholes or wells occurred in the area,
and to identify the usage of the groundwater extracted from such sources. Boreholes
identified in the study area were sampled and the groundwater was analysed to determine
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 109
plant on a coastal aquifer
the concentrations of hexavalent chromium, in order to ensure that there was no health
risk to users from such sources.
o There were no private boreholes found in or close to the affected area. The boreholes
found were mainly industrial boreholes in other industries around the manufacturing
plant including the turf club site. These boreholes were in the uncontaminated aquifer and
most of them were either blocked or destroyed.
e A total of 113 hand auger holes and wash bore drilled boreholes were put down in phases
on the manufacturing plant site and neighbouring area over the period May 2004 to
August 2005. The boreholes were installed to establish the subsoil conditions and to
facilitate the monitoring and sampling of the groundwater in the various aquifers
underlying the study area.
• The fill underlying the site occurs from the surface to depths in the range of
approximately 0.4 metres to 2.1 metres below existing ground level. The fill generally
comprises brown to dark grey, silty sand to slightly clayey sand, and contains abundant
gravel and rubble in places. The fill overlies the harbour bed sediments, which generally
occur in four predominantly sandy aquifer horizons interlayered with clay layers of
various composition and thickness. The harbour bed sediments overlie sandstone of the
Natal Group or sandy siltstones of the St Lucia Formation at depths of between
approximately 28 and 32 metres below existing ground level on the manufacturing plant
site. The weathered sandstone immediately below the harbour beds generally comprises
residual, highly weathered, orange brown, slightly clayey to silty sand. With depth the
sandstone typically becomes less weathered, grading into pinkish maroon sandstone
bedrock which extends to depths in excess of 100 metres below the site.
• The aquifer parameter tests were conducted to determine the transmissivities and the
hydraulic conductivities of the aquifers underlying the manufacturing plant site. The
transmisivities ofO.12 m2/d, 0.29 m2/d and 0.02 m2/d were estimated in aquifer 2, aquifer
3 and aquifer 4 respectively. This implies that the ease with which the water moves
through aquifers 3 would be faster that in aquifer 2 and aquifer 4.
• The hydraulic conductivities of 1.67 mid, 0.12 mid, 0.29 mid, 0.02 mid and 2.23 mid
were estimated in aquifer I, aquifer 2, aquifer 3, aquifer 4 and sandstone aquifer
respectively, indicating the rate of movement of water through the sandstone aquifer and
aquifer 1 would be faster than in aquifer 2, aquifer 3 and aquifer 4.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 110
plant on a coastal aquifer
• Groundwater occurred at the approximate depth of 1.25 mbgl, 1.60 mbgl, 1.63 mbgl, 2.13
mbgl and 14.32 mbgl in aquifer 2, aquifer I, aquifer 3, aquifer 4 and sandstone aquifer
respectively. The shallow groundwater levels in aquifer 1 and aquifer 2 suggested that
these aquifers could be vulnerable to contamination through washout of soluble Cr(VI) in
the soils by high groundwater table. However, the observed high Cr(VI)-concentrations
in aquifer I and 2 could not be explained by the latter process only.
(0) Groundwater levels have remained relatively constant throughout the study period of 5
years, indicating the historical groundwater level in the area. The graphical plots of
monitoring data showed that the notable response in some boreholes could be associated
with seasonal groundwater fluctuations.
• Based on the groundwater level contour plots, it is evident that the direction of
groundwater flow in aquifers 1 to 3 was from the west to the east.Within Aquifer 4 and
the Natal formation the groundwater flow was from the north west to the south east in
principle corresponding to the regional groundwater flow at depth from the hills toward
the sea.
• The highest measured Cr(VI) concentrations in groundwater were found in aquifer I and
aquifer 2 underlying old closed or dismantled production facilities where sodium
dichromate (SDC) liquid was produced or handled between 1945 and 1990. Cr(VI) was
only detected in aquifer 3, in the limited area underlying the manufacturing plant,
immediately above the "Hippo mud" clay. In the aquifers below the "Hippo mud" clay,
aquifer 4 within the harbour bed sediments and especially within the sandstone bedrock
where groundwater is extracted for irrigation at the turf club site, no hexavalent
chromium was detected.
• The highest measured Crflll) and Cr(VI) concentrations in soils were found on the
manufacturing plant in areas underlying old closed or dismantled production facilities
where sodium dichromate (SDC) liquid was produced or handled between 1945 and
1990.
II) Within the residential area and turf club site, low levels of Cr(Ill) and Cr(VI) were
detected in the soil samples and this could be associated with the historical surface run-
offfrom the plant site.
• As part of risk assessment the primary source at the manufacturing plant was addressed
by removing old closed or dismantled production facilities where sodium dichromate
(SDC) liquid was produced or handled between 1945 and 1990.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufactunng 111
plant on a coastal aquifer
Soil and groundwater sampling was conducted and revealed the secondary sources to be
the affected surface soils «O.3m), affected subsurface soils (>O.3m) and dissolved
groundwater plume. The potential transport media for the contaminants at the site were
found to be the soil (through leaching to groundwater) and groundwater (through
dissolved plume migration).
• The exposure pathways of concern in the study area were found to be soil, air and
groundwater.
• Seepage velocity values ofO.0864 mid, 0.079 mld, 0.0501 mld, 0.0006 mld and 0.0391
mld were estimated in aquifer I, aquifer 2, aquifer 3, aquifer 4 and sandstone aquifer
respectively. This suggests that the rate of movement of hexavalent chromium in sandy
aquifer I and aquifer 2 would be faster than in the sandy aquifer horizons aquifers 2 and
4, and sandstone aquifer.
til Based on the calculated retardation factors it is clear that retardation of the Cr(VI) was
expected to occur at the investigated site. The retardation factors of 77, 100, 102, 102,
and 114 were calculated in sandstone aquifer, aquifer I, aquifer 2, aquifer 4 and aquifer
3 respectively. This implies that Cr(VI) would be adsorbed the most in aquifer 3 as
compared to the other aquifers. Based on the chemical results of Cr(VI), it was evident
that low levels of Cr(VI) in aquifer 3 were detected away the manufacturing plant as
compared to the concentrations in aquifer 1 and aquifer 2 , suggesting that Cr(VI) was
retarded the most in aquifer 3.
• Based on the results of the risk assessment for the exposure scenario soil to human in, it
is evident that the measured concentrations both for Cr(lII) and Cr(VI) in the soil samples
taken on the manufacturing plant site were always below the SSL's for ingestion and
dermal contact for commercial/industrial areas. Beneath certain areas of the plant site, the
Cr(VI) concentrations in the soil exceeded the SSL's for inhalation of fugitive
particulates. These contaminant values do not pose a health risk to workers on the plant
site or on neighbouring industrial sites, as in all instances the ground surface is covered
by buildings and/or paved in concrete/asphalt.
• The measured concentrations of Cr (VI) in the upper 30cm of soil in the residential area
and turf club site were much lower than SSL's for inhalation as well as ingestion/dermal.
Similarly, the concentrations of Cr(VI) in the unsaturated soils at greater depths were
below the SSL's for ingestion and dermal contact.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 112
plant on a coastal aquifer
The majority of the soil samples in the residential area and turf club site reported Cr (VI)
concentrations at levels below the method detection limit ofO,02mg/kg. All deduced
Cr(III) concentrations ofthe soil samples were well below the SSL in the neighbouring
area. Hence neither of the concentrations ofCr(VI) and Cr(III) found in the soils of the
neighbouring area pose risk to humans.
o Based on the results of the risk assessment for the exposure scenario soil to groundwater
in, it is evident that on the manufacturing plant site outside the groundwater plume area,
the Cr(VI) concentrations in the soils were below the SLo In the vicinity of the 'hot spots'
(active sources) the Cr(VI) concentrations were above the SLoTherefore these
contaminated soil areas have an impact on the groundwater plume.
ID In the residential area and turf club site, the measured Cr(VI) concentrations in the soil
samples outside the plume area and within the plume were all below the SL of38 mg/kg.
Hence the migration of Cr(VI) from the soil to the groundwater in the neighbouring area
is of no concern and does not pose a risk.
ID Numerous studies and scientific papers have indicated that the soluble Cr(VI) is not taken
up easily by plants. Iftaken up by plants or in general by living tissue it is rapidly
converted to Cr(IU). Cr(III) in plants does not pose any risk to human health since it is
an important component of a balanced human diet. Hence the exposure scenario soi I to
plant to human does not pose a risk.
• Based on the results of the risk assessment for the groundwater contamination, it is clear
that the amount of the Cr(VI) concentrations in the groundwater plume exceeded all risk
based screening levels for drinking water, irrigation and livestock. The contaminated
groundwater is clearly not suitable for drinking, irrigation and livestock, as exposure to
large quantities of the contamination could lead to serious health effects. However, the
contaminated groundwater starts approximately 1 to 2 meters below the ground surface.,
provided a person does not come into direct contact with the contaminated water through
drinking or skin contact, there would be no risk of adverse health effects to the person.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 113
plant on a coastal aquifer
7.2 Recommendations
Based on the findings of this research, and theoretical models, it becomes obvious that there is
need for further research, as recommended below:
• From the launched project Department of Water and Evironmental Affairs have to
establish the guidelines of assessing the chromium contamination, formulation of the
water quality standards with regard to chromium and finally generate the law which will
then enforce the industries to allocate enough budgets for environmental management in
South Africa.
• The authorities (i.e. DWEA, ET) have to be fully involved during the investigation of the
chromium contamination since their involvement can then help in the disclosure of the
research findings to the interested and affected parties. This is because most of the
contamination which is induced in the groundwater ends up with the negative impacts to
the public.
• An environmental awareness should be implemented in order to make the public aware of
the chromium in the subsurface environment. This awareness can be done through
workshops, by simply inviting the public as well as knowledgeable people who can then
discuss the issue of chromium contamination in the subsurface focusing on its detrimental
consequences to the environment.
• In terms of risk-based approach, DWEA accepts RBCA until South African risk
assessment protocols are developed. This should be communicated to all officials likely
to deal with chromium risk assessment. Eventually, DWEA should write an official
protocol about the acceptance ofRBCA so that there is consistency until South African
risk-based approach has been established.
In order to avoid and/or minimize the chromium soil and groundwater contamination in the
subsurface there should be:
• An inter-departmental collaboration as well as reporting incidents and progress reports to
both DWEA and DET. This means that there should be a close relation between the
departments as well as the consistency when it comes to the frameworks of assessing the
ground water contamination. Industries and consultants should supply the authorities
Investigation into the impact of chromium contamination in the soils and groundwatcr underlying a manufacturing 114
plant on a coastal aquifer
with the incident report which include all the actions taken to mitigate the problem in
question. The progress and pitfalls should be forwarded to the authorities in the form of
a report.
• An acceptance of some interim standard/approach for evaluating and monitoring the
contamination. Consultants should always keep in touch with the authorities in order to
be able to know if there is any interim approach developed to be used for conducting
contamination assessments.
Based on the results, findings and conclusions drawn from the Conceptual Site Model (CSM) and
the preliminary risk assessment it is recommended that the following corrective actions or
mitigation measure be implemented and administered:
• Appropriate work procedures should be developed and applied during all future
excavations and below ground level construction within the plume area. These
procedures should comprise protective and safety measures to prevent worker exposure to
the Cr(VI) contaminated groundwater.
• Residents and owners of neighbouring properties must continue to be made aware of the
extent of the chromium contamination in the groundwater beneath the study area, and the
need to avoid excavations and contact with the groundwater in the designated
precautionary area.
• Groundwater extraction boreholes or wells must not be installed within the plume area
except for remedial actions. The relevant authorities (DWEA) should be requested to
assist in this regard by applying the necessary controls to eliminate any future risk to
workers and residents.
• A detailed remediation plan to treat the "hot spots" (active sources) beneath the
manufacturing plant site should be developed. This plan should include selected
excavation and removal of contaminated soil and groundwater to landfill, and replace
with clean soil/concrete/or treated soil.
• Groundwater containment system should be designed and implemented to prevent
contaminants in the groundwater migrating off site.
• Groundwater extraction system at the hot spots should be designed and implemented in
order to lower the groundwater table and reduce chromium concentrations in the 1st and
2nd aquifers.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 115
plant on a coastal aquifer
• The effectiveness of the groundwater extraction and containment system should be
monitored in reducing chromium concentrations.
• Site-specific target levels (SSTL's) for soil and groundwater cleanup goals should be
established.
Investigation into the impact of chromium contamination in the soils and groundwater underlying a manufacturing 116
plant on a coastal aquifer
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APPENDIX A
Borehole logs (selected)
Borehole log - BH204A
Dept (mj ocahtv X: -3759.086 Y. -33 3782.392 Z: 15.440
Geology
o
0.00 0 85 SOil: Ora e brown gravelly wit fill
2
0.85·4.40 S/lND: Greyish brow silty
4
4 40 - 5 20 5/1 D: Yellowish brown cl yey
6 5.20 - 6.40 (lilY Yellowls grey sa dy
8 6.40 - 9.00 SAND: Yellow is brow silly
9.00 - 9.75 (lilY Orange brow sa dy
10
12
14
Borehole log - BH20SA
Depth (mj oe lity X: -3763.60 Y: -33 3844.535 Z: 15.534
lithology Geology
o
0.00 - L20 GRAVEL: Dark grey to purple sandy
L20 - 2.00 501 : Dark brow silty with fill
2
4 2.00 - 5.60 SA D. Yellowish brown clayey
6 560 - 6.40 CLIIY: Yellowish brown sandy
6.40 - 7.20 SA D Orange brown clayey
7.20 - 8.00 CLIIY: Dar grey silty
8
8.00 - 9.20 SAND. Yellowish grey silty
9.20 - 10 0 CLIIY: Dar grey silty
10
12
14
Borehole log - BH207A
De th (m) Locality X: -3661. 20 Y: 3313854.310 Z. 13.470
ithology Geology
0
000 200 SAND: Greyis brow clayey
2
200 - 3 00 SAND: Brow ish grey clayey
4 3 00 - 4 00 CL/\Y Reddis rown s i tly clayey
4 00 600 SAND: ellowis brow clayey
6 6 00 6 60 CL/\Y Dark grey sllty
660 - 7 40 SAND: Grey to brownis grey silry
8
7,40 - 9 20 CL/\Y Brow is grey sandy
10
12
14
Borehole log - BH212A
De th (m) Locality X: -3825.773 Y: 3313823.598 Z· 16 580
Geology
o
000 - 105 SOIL:YeUowis brown sandy Wit fill
2 1.05 - 3 00 SAND: Yellowish brown cl yey
3.00 - 4.00 SAND: Grey clayey
4
400 - 7,40 CL/\Y Yellowish brow sa dy
6
8
7,40 1000 SAND: Yellowls grey clayey
10
10.00 - 13.00 SA 0 Dark grey clayey
12
14
Borehole log - BH215A
til (fil) o dlily : -3723.2 Y:-33 378 .933
ilty
clayey
LAY:Gre ~ilty
Sorehole log - SH20a
Depth ( lo dhty X: 3585.732 Y: 3313763.598 Z: 12.071
lithology
o
0.00 1.30 SOil: Dark bro vn sandv with fill
1.30 3.00 SAND: Grey clayey
4 3.00 5.00 CLAY: Grey sa dy
5.00 6.00 SAND: li ht brownish rey ~ilty
6.00 9.00 CLAY: Grey sa dy
8
9.0 12.0 SAND' lie treddis erey silty
12
12.0 15.5 CLAY: Dark 'rey sandy
16
8orehole log - SH213
Depth (ml Lo hty X. 3706579 Y: 3313882.941 Z:13.923
LitholoBY G oloCY
0.00 1.30 SOIL' Greyish brown sa dy with rill
1.30 4.00 SAND: Brown silty
4.00 7.00 CLAY:Yellowis brown sal dy
7.00 8.00 SAND. Browrns grey
8.00 10.0 CLAY:Brown sandy
10.0 13.0 SAND: BI bh grey I yey
13.0 15.45 CLAY:Dark C'CY silty
Sorehole log - BH403
Deet" (ml Local ty X -3762.451 Y 3 13679.372 Z.15.721
o
.90 SI\ND. Greyis'l brow clayey
5 4.90 6.30 CLAY rey silty
6.30 - 6.80 SAND. Grev s Itv
6.80 - 7.20 CLAY. Grey silty
7.20 - 9.80 I\ND. Brownish rey clayey
10 9.80 - 10.80 CLAY: ght cr y si ty
10 80 - 1 .30 SA D: Grey to V low si brow-i
15
20 1 30 - 22.80 CLAY: Oa-k grey S Ity
25
22 80 - 32.45 SA D: Grey to Brownis rey clayey
30
5
Borehole log - BHD5
ept m L licy - X: 23 ~!8 Y.1 333
- 24. CLAY·Dar br wn il
- j. ~AND. Ye owish brown cl yey
3. - ~.:.. SA TO I: p,.. I aroon we t ered
APPENDIX B
Results of particle size distribution analysis
DETERMINATION OF SOil PARTICLE SIZE DISTRIBUTION
Particle size (mm) ("k) passing
19
13.2
4.75
2 100 100 100
0.425 98 84 96
0.075 16 17 10
0.06 11 12 8
0.05 10 12 8
0.026 10 10 8
0.015 10 10 8
0.01 10 10 8
0.0074 10 8 8
0.005 9 8 6
0.0036 8 8 6
0.002 8 8 6
0.0015 8 7 6
Figure 1: Grain-size distribution curves for soil samples
100
90 - P"_--_ f--+-
BH202(lm)
-BH209(4m)
BO -~V -BH210(3m)
~ 70 ------ f--
co
-c:: 60 -- --
t - 1-
50 -- " _.-Ol --
D-
ceo 40s.. 1,4c: 30 "
I! V
a.... 20
10
o
0.001 0.01 0.1 10
Particle size (mm)
BH202 BH210 BH209
3 4
BS 5930 Classification BS 5930 Classification
Gravel ("k) 2 16 8
Sand ("k) 87 72 86
Silt(%) 3 5 2
Clay {"k) 8 8 4
Material description SAND Silly SAND SAND
0.007 0.01 0.08
0.07 0.07 0.09
0.16 0.18 0.19
0.19 0.23 0.23
0.0034 0.0049 0.068
DETERMINATION OF SOil PARTICLE SIZE DISTRIBUTION
BH204 BH205 BH202
7 7 8
Partide size (mm) (%) passing
19
13.2
4.75
2 100 100 100
0.425 96 98 97
0.075 11 20 19
0.06 10 14 16
0.05 10 14 15
0.026 10 12 14
0.015 10 11 14
0.01 10 9 14
0.0074 10 8 12
0.005 10 8 12
0.0036 8 6 12
0.002 8 6 11
0.0015 8 6 10
Figure 2 : Graln-size distribution curves for soil samples
100
90 BH202(&n)
f -BH2o.1(7m)80 -BH205(7m)
70
.!.... 60 Vc.. 50 IIlO
Q. 40 - ~- .- 1--- II -~- f--
ti - --
Ol
Jc! 30 f--
.- -- - vI
ti
!! 20
at.i. _/
10 ----
0
0.001 0.01 0.1 10
Particle size (mm)
BH204 BH205 BH202
7 7 8
BS 5930 Classification BS 5930 Classification
Gravel (%) 4 2 2
Sand (%) 86 84 81
Silt(%) 2 8 5
Clay(%) 8 6 11
Material description SAND SAND SAND
0.005 0.013 0.0016
0.08 0.065 0.055
0.17 0.155 0.15
0.2 0.18 0.18
0.0022 0.0063 -
DETERMINATION OF SOil PARTICLE SIZE DISTRIBUTION
SH201 SH203 SH202
11 13 16
Particle size (mm) (%) passing
19 100
13.2 99
4.75 98 100
2 100 98 99
0.425 97 93 91
0.075 19 30 58
0.06 16 26 31
0.05 16 26 30
0.026 14 23 18
0.015 14 22 16
0.01 13 21 14
0.0074 12 18 12
0.005 12 17 11
0.0036 11 15 10
0.002 10 10 9
0.0015 9 8 7
Figure 3 : Grain-size distribution curves for soil samples
100
90 - L BH201 (11m)
eo V;i - BH202 (16m)
/ ï -BH203(13m)70 f-
~ V.. 60 t-r- -c.'". 50 ..... - /lOa... 40 V --r-
DI
E.. 30 -.~. ._- -~ ,.,..~ 1- 1--- r-20a.. l- t.- !-'10 T - -
I
0
0.001 0.01 0.1 10
Particle sIze (mm)
SH201 SH203 SH202
11 13 16
SS 5930 Classification SS 5930 Classification
Gravel (%) 3 5 8
Sand (%) 81 68 61
Silt(%) 6 16 22
Clay (%) 10 10 9
Material description SAND SiltySAND Silty SAND
0.002 0.001 0.004
0.04 0.004 0.015
0.17 0.15 0.07
0.18 0.17 0.085
- - 0.0016
DETERMINATION OF SOil PARTICLE SIZE DISTRIBUTION
Particle size (mm) (%) passing
19 100
13.2 100
4.75 100
2 100 100
0.425 95 100 99
0.075 19 17 79
0.06 13 16 24
0.05 13 15 16
0.026 11 12 16
0.015 9 10 15
0.01 6 6 14
0.0074 6 4 12
0.005 1 4 9
0.0036 1 2 8
0.002 0 2 5
0.0015 0 2 4
Figure 4 : Grain.size distribution curves for soil samples
100
90 .- -+-+-++H-ti- .-1--'- -- 1---7~V - - - - -1 -BH401(27m)
BO --+---+--+++hH'!-V---+----1--+1-HHt--t-. ----i BH403 (27m)
+---+--+-+-H+++~---+-+-j ++fH+-+Vf-lL-++H+lt- ---- - ---'t:R+r::,...~B'=tH=D5'1("'~4'fm="+")1"~170
~ 60
Ol I -
i"i 50 f-- -- - ---+-+++I---+-+-+--I--41+H:;
Q. 40 - .- - - 1-- -_. -!--- ._--
Cl
Cl
~.. 30 +-~f--I_-++-++Hr---t--r- ~~r-+-,_++++Hr---r-r---
.-----+-+----1-+.-1-+.+1
e 20 .. - r-·-f-- ..- - '.---Hr+-H--+_'-++-~
aC..l
10 - ,- --0
0.001 0.01 0.1 10
Particle size (mm)
SS 5930 Classification SS 5930 Classification
Gravel (%) 6 0 0
Sand (%) 81 84 85
Silt(%) 13 14 6
Clay (%) 0 2 9
Material description SAND SAND SAND
0.02 0.015 0.006
0.065 0.005 0.015
0.157 0.156 0.065
0.19 0.19 0.07
0.013 0.0085 0.0033
DETERMINATION OF SOil PARTICLE SIZE DISTRIBUTION
SHD5 SHD3 SHD1
27 30 31
Partide size (mm) (%)passing
19 100 100
13.2 100 100
4.75 100 100 100
2 100 99 100
0.425 99 94 99
0.075 85 12 72
0.06 42 9 19
0.05 28 9 13
0.026 6 8 6
0.015 4 8 6
0.01 2 8 6
0.0074 2 7 6
0.005 2 6 6
0.0036 2 6 6
0.002 2 6 5
0.0015 2 5 4
Figure 5 : Grain-size distribution curves for soil samples
100
.-::
90 n -BHD1(31m)
-: .- BHD3 (3Om)60 - -BHD5(27m)
70 f-. --
~ 60 r-- ~-- - --
Ccl
ti 50
:.I
Cl. 40 I
•8... 30 1/ë -~.. /20
D.. / V
10 - 'l- ._"
0 II
0.001 0.01 0.1 10
Particle size (mm)
SS 5930 Classification SS 5930 Classification
Gravel (%) 1 5 0
Sand (%) 95 86 94
Silt(%) 2 3 0
Clay(%) 2 6 6
Material description SAND SAND SAND
0.03 0.07 0.04
0.035 0.08 0.055
0.065 0.18 0.07
0.065 0.21 0.07
0.025 0.05 0.032
DETERMINATION OF SOil PARTICLE SIZE DISTRIBUTION
Sameie No. BH202 I BH203 I BH204 I BH205 BH201II De(!th (ml II II 2 5 5 5 I 6 II
Particle size (mm) (%) passing
19
13.2
4.75
2 100 100 100 100 100
0.425 98 98 99 98 99
0.075 34 44 70 21 55
0.06 29 36 67 18 42
0.05 27 33 65 18 40
0.026 27 31 63 18 36
0.015 27 31 61 18 36
0.01 26 31 60 18 35
0.0074 26 31 59 18 33
0.005 24 30 58 17 31
0.0036 24 29 55 16 30
0.002 24 28 54 16 29
0.0015 21 27 52 16 28
Figure 6 : Grain-size distribution curves for soil samples
110
100 i- - i-i- II f- .IJ. III lTI
~ ~ -BH201(6m)90
-BH202(2m)
80 i-
- 1~r .- -BH2Q3(Sm)~ 70 - BH20<4(Sm)Ol 60c: 1-' -- 1-1-- BH205(Sm)•: 50 1--1- I- I-Q.
40 - ... i~ I-
f· 30 - 1- l-I•! 20 L - - f-I- - I- i-- --a.. 10 - - -- - - r--r .~ -
0
0.001 0.01 0.1 1 10
Particle size (mm)
II Sample No. II II BH202 I BH203 I BH204 I BH205 BH201 II
II Depth(m} Jl II 2 I 5 I 5 I 5 I 6 II
BS 5930 Classification BS 5930 Classification
Gravel (%) 0 0 0 0 0
Sand (%) 70 64 33 82 58
Silt(%) 6 8 14 2 13
Clay (%1 24 28 53 16 29
Material description SAND Clay SAND CLAY Clay SAND Clay SAND
dla - - - - -
d15 - - - - -
dso 0.12 0.019 - 0.15 0.017
d60 0.15 0.14 0.0017 0.175 0.019
lo - - - - -
DETERMINATION OF SOil PARTICLE SIZE DISTRIBUTION
Sameie No. II BH204 I BH205 I BH202 BH203 II
II Deeth (ml II II 10 I 10 I 11 12 II
Particle size (mm) (%) passing
19 100
13.2 99
4.75 96
2 100 100 100 95
0.425 97 98 98 91
0.075 40 56 49 59
0.06 35 50 41 44
0.05 34 49 41 42
0.026 31 45 37 33
0.015 30 43 37 27
0.01 29 39 35 23
0.0074 28 37 33 18
0.005 27 35 31 16
0.0036 25 31 31 15
0.002 23 31 30 12
0.0015 21 27 29 9
Figure 7 : Grain~ize distribution curves for soil samples
110
100 t--- ,-- -I- - - I:! i~ HillJ
90 ,- - ~ "frf -BH202 (11m)
80 -- 1-'l- t--- -
1-- BH203(12m)
~- 70 ~ -1- ~ -,- -- - ,-~. -BH204(1Om)Cl 60 - - -- -1-- I_ k ~ -BH205 (1Om)c:
i·i 50 ~-1-- _• 1- - 1;:::- '---- -,-•Q. 40 ~ --;-I' -- - -- - - - -1..: 30 ~""7 k r--: - - 1- --I- -.. 1---!! 20 -e: - - 1-- - ,- I-- 1-1-a..
10 ~ I- c- -
0
0.001 0.01 0.1 1 10
Particle size (mm)
II Sample No. II BH204 BH205 BH202 BH203
Il Depth (m) Jl II 10 I 10 I 11 I 12 II
BS 5930 Classification SS 5930 Classification
Gravel (%) 0 0 0 5
Sand (%) 65 51 59 49
Silt(%) 12 18 11 34
Clay ("kl 23 31 30 12
Material description Clay SAND Clay SAND Clay SAND Silty SAND
d10 - - - 0.00155
d15 - - - 0.0013
dso 0.1 0.06 0.08 0.065
d60 0.15 0.09 0.12 0.075
ID - - - -
DETERMINATION OF SOIL PARTICLE SIZE DISTRIBUTION
Sample No. II BH205 BH201 BH202
Depth (m) II ~ 12 I 14 I 16 II
Particle size (mm) (%) passing
19
13.2
4.75 100
2 100 100 99
0.425 94 94 91
0.075 36 46 58
0.06 31 40 31
0.05 30 39 30
0.026 28 34 18
0.015 28 32 16
0.01 27 28 14
0.0074 26 25 12
0.005 24 23 11
0.0036 23 23 10
0.002 21 19 9
0.0015 19 13 7
Figure 8 : Grain..size distribution curves for soil samples
110
lOD - 1- - -BH201 (14m)~
90 ~ [/r -BH202 (lSm)
BO f- _- -- I~I- It - _ BH205(12m)
- 70 - - _t- t-~
. 60 f-- - - -- - ~ 1-- --ei.'i". 50 -
Cl. 40 r- I-
II
s'c" 30 ~ - v-t:::t 1- -I- - 1- -- -t-
II
!! 20
II l--- I--'V
Cl. I--
, 10 1-/ - t- -- -I- t--- r-t- - -- - - -0 .1
O.ODl 0.01 0.1 1 10
Particle size (mm)
II Sample No. II BH205 BH201 BH202
II Depth (m) II II 12 I 14 I 16 II
BS 5930 Classification BS 5930 Classification
Gravel (%) 0 0 1
Sand (%) 69 60 68
Silt(%) 10 21 22
Clay ("Ál) 21 19 9
Material description Clay SAND SIIty clayey SANe Silty SAND
dlO - - 0.004
dl5 - 0.00175 0.015
dso 0.12 0.09 0.07
dso 0.165 0.13 0.08
lo - - 0.002
APPENDIX C
Fe-Method (Data sheets and T-value estimation)

(To obtain correct S-value. use
BASIC SOLUTION
(Using derivatives + subiective information about boundaries)
(No values of Tand S are necessary)
sWell (Extrapol.time) =.~~~~~II
Q_sust (lIs) ='---Be~ase'-======-::----v;;or;tëiii;e4
(Using derivatives+ knowledge on boundaries and other boreholes)
(Late T -and S-values a priori + distance to boundary)
T-Iale [mz/d] = (enter) ---+
S-Iate = (enter) ---+
1. BOUNDARY INFORMATION (choose a or b)
(a) Barrier (no-flow) boundaries ---+
Bound. distance a[meter] : (enter)
Bound. distance b[meter] : (enter)
s_Bound(t = Extrapol.time) [m] =
(b) Fix head boundary + no-flow __.
Bound. distance to fix head a[meter] : (enter)
Bound. distance to no-flow b[meter] : (enter)
s_Bound(t = Extrapol.time) [m] =
Total amount of
abstracted per month (rn'') =
COMMENTS
Q_sust with 68% safety =
Q_sust with 95% safety =
SA Harbour beds
Durban
obtain correct S-value. lIse
BASIC SOLUTION
(Using derivatives + subjective information about boundaries)
(No values of Tand S are necessary)
sWell (Extrapol.tlme) =~!I]~~!I]ï
Q_sust (115)
Average Q_sust (lis) =~-""::-:~-l
with standard deviation: 0.00
no information exists about boundaries advanced solution and to final recom
(Using derivatives+ knowledge on boundaries and other boreholes)
(Late T-and S-values a priori + distance to boundary)
T-Iate [m2/d] = (enter) --+
S-Iate = (enter) ----.
1. BOUNDARY INFORMATION (choose a or b)
(a) Barrier (no-flow) boundaries -+
Bound. distance a[meter] : (enter)
Bound. distance b[meter] : (enter)
s_Bound(t = Extrapol.time) [m] :
(b) Fix head boundary + no-flow -..
Bound. distance to fix head a[meter] : (enter)
Bound. distance to no-flow b[meter] : (enter)
s_Bound(t = Extrapol.time) [m) =
2. INFLUENCE OF OTHER BOREHOLES
s_(influence of BH1,BH2) =
SOLUTION INCLUDING BOUNDS AND BH's
Fix head + No-flow: Q_sust (115)=I---:~~~+-~~~+-~~~--+-~~~--i
No-flow: Q_sust (lis) =~~:.::..:.yL~~:.::..:.yLL=~~_L___:E~L~
Enter selected Q for risk analysis = (enter)
COMMENTS
a_sust with 68% safety =
a_sust with 95% safety:
Harbour beds
Durban
obtain correct S-value, use
BASIC SOLUTION
(Usingderivatives + subjective Information ebout boundaries)
(No values of Tand S are necessary)
sWell (Extrapol.time)
Q_sust (lis) =I--fe~~-==::::===-::-~~~;;-I
Average Q_sust (lis) =1
with standard devlation-I--~'=--I
no information exists about boundaries advanced solution;;an;;;d~~;-fu;:;;r;'"r"nll"""nrl"tinn
ADVANCED SOLUTION
(Usingderivatives+ knowledge on boundaries and other boreholes)
(Late T-and s-vetues a priori + distance lo boundary)
T-Iate [ml/dJ- (enter) __.
s-tate - (enter) --+
1. BOUNDARY INFORMATION (choose a or b)
(a) Barrier (no-flow) boundaries __.
Bound. distance a[meter] : (enter)
Bound. distance b[meter] : (enter)
s_Bound(t = Extrapol.lime) [m) =
(b) Fix head boundary + no-flow _____.
Bound. distance lo fix head a[meter) : (enter)
Bound. distance to no-flow b[meter) : (enter)
s_Bound(t = Extrapol.tims) [m) =
2. INFLUENCE OF OTHER BOREHOLES __.
BH1~ ~ ~~~~~ __ ~~~ __ ~
BH2~~~ __ -+__~~ __+-~~~ __~ __~~~--4
,_(Influence of BH1,BH2) =
SOLUTION INCLUDING BOUNDS AND BH's I--___;;.;.;;.;:.._-'-_..;;.;.;;.;:.._--I-_::..;.;:..;..::....;;.;._-'- __ ...;;:..;'----;
Fix head + No-flow: Q_sust (lis) =1-:";";;";:':';;;':""-+-";;';:":-;":':-:--+--:-;;";:":'':'';:';:'--4---:';:''':'';'':'';:';:'---4
No-flow: Q_sust (lis) =~~~~~~~~L~~~_J____:~~~~
Enter selected Q for risk analysis = (enter)
COMMENTS
Q_sust with 68% safety =
Q_sust with 95% safety =

obtain correct S-value, use
BASIC SOLUTION
(Using derivatives + subjective information about boundaries)
(No values of Tand S ore necessary)
sWell (Extrapol.tlme) -1-----:~-=--+-----::=:-==--I-_;:;..;.;,,~-_t_--="=:7_-__;
Q_sust (115) =I--Be~~-==::::===~~~~;el
Average Q_sust (115) =1
with standard deviation= 1---".0"";:.0'""1----1
advanced solution and to final
(Using derivatives+ knowledge on boundaries and other boreholes )
(Late T-and S-values a priori + distance to boundary)
T-Iate [m2/dJ" (enter) _.
S·late = (enter) -+
1. BOUNDARY INFORMATION (choose a or b)
(a) Barrier (no-flow) boundaries -+
Bound. distance a[meter] : (enter)
Bound. distance b[meter] : (enter)
s_Bound(t = ExtrapoLtime) [m] =
(b) Fix head boundary + no-flow -+
Bound. distance to fix head a[meter] : (enter)
Bound. distance to no-flow b[meter] : (enter)
s_Bound(t = Extrapol.time) [m] =
lor barrier boundaries)
COMMENTS
a_sust with 66% safety =
a_sust with 95% safety =

(To obtain correct S-value, usa
BASIC SOLUTION
(Using derivatives + subjective information about boundaries)
(No values of Tand S are necessary)
sWell (Extrapol.time) =m~~~ljl
Q_sust (Ifs)
(Using derivatives+ knowledge on boundaries and other boreholes)
(Late T-and S-values a priori + distance to boundary)
T -late [mZ/dJ = (enter) ---+
S-Iate = (enter) -+
1. BOUNDARY INFORMATION (choose a or b)
(a) Barrier (no-flow) boundaries --+
Bound. distance a[meter] : (enter)
Bound. distance b[meter] : (enter)
s_Bound(t = Extrapol.time) [m] =
(b) Fix head boundary + no-flow
Bound. distance to fix head a[meter] : (enter)
Bound. distance to no-flow b[meter] : (enter)
s_Bound(t = Extrapol.time) [mj =
2. INFLUENCE OF OTHER BOREHOLES
s_(inftuence of BH1,BH2) "
SOLUTION INCLUDING BOUNDS AND BH's
Fix head + No-flow: Q_sust (Ifs) =I----'~~~_+_±::~~_+---::=±'_;::_:::___f_-~~~__I
No-flow: Q_sust (Ifs) =J-.;~~~~~~~L~~~-L___:~~~~
Enter selected Q for risk analysis = (enter)
COMMENTS
Q_sust with 68% safety =
Q_sust with 95% safety =

-F.e-METHOD: Estimation of the sustainable yield of a boreholeI:
Extrapolation time in years - (enter) 2 1051200 Extrapol.time in minutes
Effective borehole radius (r.) - (enter) 0.50 •r- #DIV/OI t- Est. r. [From rte) sheeta (115) from pumping test - 0.22 3.32E-03..t- S-Iate +r- Change r.5 (available drawdown), sigma 5 - (enter) 8.3 - Sigma_s from risk
Annual effective recharge (mm) = 830 s_available working drawdown(m)
tIend) and s(end) of pumping lest - 1440 6.44 End lime and drawdown of lest
Average maximum derivative - (enier) 1.5 .-i- 2.7 Estimate of average of max denv
Average second derivative - (enter) 0.0 •r- 0.0 Estimate of average second denyDerivative at radial flow pertod - (enter) 0.00 •i- 1.65 Read from derivative graphT-early[m'/d) - #DIV/OI AqUl thick (m) 1 3
Tand S estimates from derivatives T-Iate [m'/d] - 2.32 Est. S-Iate = 1.65E-04
(To obtam correct s-vaïue. use program RPTSOLV) S-Iate - 3.30E-04 S-estimate could be wrong
BASIC SOLUTION
(Using derivatives + subjective information about boundaries) Maximum influence of boundanes at long time
(No values of Tand S are necessary) No boundaries 1 no-flow 2 no-flow Closed no-flow
sWell (Extrapol.time) "I 10.58 14.88 19.17 32.06
Q_sust (lis) = 0.17 0.12 0.10 0.06
Best case Worst case
Average Q_sust (lis) =1 0,10
wilh standard devmtion> 0.05 I
(If no information exists aboul boundaries Skipadvanced solution and go to final recommendation)
ADVANCED SOLUTION
(Using derivatives+ knowledge on boundaries and other boreholes)
(Late T-and S-values a priori + distance to boundary
T-tate rmz/dj - (enter) __
)_. 2.32
s-tate - (enter) _. 1.00E-03
1. BOUNDARY INFORMATION (choose a or b) (Code -9999 - dummy value If not applicable)
(a) Barrier (no-flow) boundaries --+ Closed Square 1 Single Barrier Intersect. 90" 2 Parallel Barriers
Bound. dislance a[meter) : (enter) 9999 9999 9999 9999
Bound. distance b[meter) : (enter) 9999 9999
5_Bound(t = Extrapol.time) [m) = 0.00 0.00 0.00 #NUMI
(b) Fix head boundary + no-flow _.. Closed Fix Single Fix 90"Fix+no-f1ow /I Fix+no-f1ow
Bound. distance to fix head a[meter) : (enter) 9999 9999 9999 9999
Bound. distance to no-flow b[meter) : (enter) 9999 9999
s_Bound(t = Extrapol.time) [m) = 0.00 0.00 0.00 0.00
2. INFLUENCE OF OTHER BOREHOLES _. a (lis) rem) u r W(u,r)
BHl O.OOE+OO #NUMI
BH2 O.OOE+OO #NUMI
s_(influence of BH1,BH2) = 0.00 0.00 3.69E-08 16.54
SOLUTION INCLUDING BOUNDS AND BH's
Fix head + No-flow: Q_sust (lis) = 9999.00 9999.00 9999.00 9999.00
No·flow: Q_sust (lis) = 9999.00 9999.00 9999.00 9999.00
Enter selected Q for risk analysis = (enter) -+ Sigma_s = 0.000
(Go to Risk sheet and perform risk analysis from which sigma s will be estimated: only for barrier boundaries)
FINAL RECOMMENDED ABSTRACTION RATE
Abstraction rate (lis) for 24 hr/d = (enter)
Total amount of water allowed to be
abstracted per month (mJ) = 0
COMMENTS
a_sust with 68% safety =
a_sust with 95% safety =

-F.e-METHOD: Estimation of the sustainable yield of a borehole
Extrapolation time in years = (enter) 4320 2270592000 Extrapol.time in minutes
Effective borehole radius (r.) - (enter) 0.50 •- 37.03 if- Est. r, [From rIel sheet
a (Us) from pumping test = 0.18 3.27E-03 ..if- S-Iate +t- Change r,Sa (available drawdown). sigma s = (enter) 8.2 8 I-- Sigma_s from risk
Annual effective recharge (mm) - 8.20 s_available working drawdown(m)
tIend) and s(end) of pumping test - 1440
Average maximum derivative -' (enter) 1.9 .•.-...
6.74 End time and drawdown of test
3.1 Estimate of average of max deriv
Average second derivative - (enter) 0.0 i- 0.0 Estimate of averoge second denv
Derivative at radial flow period - (enter) 1.50 .- 2.16 Read from derivative graphT-earty[m</dJ - 1.90 Aqui. thick (m) I 3.1
Tand 5 estimates from derivatives T-Iate [m</dJ - 1.54 Est. S-Iate = 1.71E-04
(To obtain correct S-value, use program RPTSOLV) S-Iate= 3.41E-04 S-ostimate could be wrong
BASIC SOLUTION
(Using derivatives + subjective information about boundaries) Maximum influence of boundaries at long time
(No values of Tand S are necessary) No boundaries 1 no-flow 2 no-flow Closed no-flow
sWell (Extrapol.tlme) = 18.17 29.63 41.10 75.50
Q_sust (lis) = 0.08 0.05 0.04 0.02
Best case Worst case
Average Q_sust (lis) =1 0.04
with standard deviation= 0.03 I
(If no information exists about boundaries skip advanced solution and go to final recommendation)
ADVANCED SOLUTION
(Using derivatives+ knowladge on boundaries and other boreholes)
(Late T-and s-values a priori + distance to boundary)
T-Iate [m2/dJ = (enter) __._. 1.54S-Iate • (enter) 1.00E-03
1. BOUNDARY INFORMATION (choose a or bl (Code -9999 - dummy value if not applicable)
(a) Barrier (no-flow) boundaries ---+ Closed Square I Single Barrier Intersect. !:IU' 2 Parallel Barriers
Bound. distance almetar] : (enter) 9999 I 9999 9999 9999
Bound. distance b[meter] : (enter) 9999 9999
s_Bound(t = Extrapol.time) (m] = 57.12 2.13 5.88 8.36
(b) Fix head boundary + no-flow --+ Closed Fix Single Fix 9O°FlX+no-flow /I Fix+no-ftow
Bound. distance to fix head a[meter] : (enter) 9999 9999 9999 9999
Bound. distance to no-flow b[meter] : (enter) 9999 9999
s_Bound(t = Extrapol.time) [mj = -3.39 -1.13 -3.22 -2.83
2. INFLUENCE OF OTHER BOREHOLES ---+ 0(115) rim) u r W(u,r)
BH1 O.OOE+oo #NUMI
BH2 O.OOE+OO #NUMI
s_(influence of BH1,BH2) .. 0.00 0.00 2.58E-11 23.80
SOLUTION INCLUOING BOUNDS ANO BH's
Fix head + No-flow: Q_sust (lis) = 9999.00 9999.00 9999.00 9999.00
No-flow: Q_sust (lis) = 9999.00 9999.00 I 9999.00 I 9999.00
Enterselected Q for risk analysis = (enter) -+ Sigma_s = 0.000
(Go to Risk sheet and perform risk analysis from which sigma 5 will be estimated: only for barrier boundaries)
FINAL RECOMMENDEDABSTRACTION RATE
Abstraction rate (115f)or 24 hrld = (enter)
Total amount of water allowed to be
abstracted per month (mj) = 0
COMMENTS
O_sust with 68% safety =
a_sust with 95% safety =

.620 S.89 .19 0.: __ 1_ 4IOIVJOI
4870 S.89 0.92 O. __ 1_ jIOlVJOI
~ 5.9 087 022 __ 1_ 4IOIVIOI
49.20 S.91 l00 022 __ 1_ #OIVJO!
_50.20 5.92 13 0: __ 1_ #DIV/O'
SUO 5.93 1.21 0.2: __ 1_ IDIVlO!
5220 5.94 1.304 022 __ 1_ IDIVIOI
5.320 5.95 I.SI 3.n 022 IIE- ___ 1_ 1__ OIOIVIOI... 0 S6 0.s ' 022 ti.tiot_ .,_ _ __ 1rOIVIOI""20 .ss 0.'" 022 ti.tiuE~ _1 IfDIVIOIS620 1.56 0.22 8. _1 IDIV/I)!5160 1.80 0.: 6. WIVIOI
5620 2.10 022 6. _1 __ IIOIVIO'
~20 6.03 '33 022 6. "_1_1_ .OIVIOI
6020 5.05 2.2& 022 _1_1_ "OIVIOI
6620 6. __
6720 8.12 __
8820 8.13 __
6920 6.14 ., __
7020 6.15 ., __
7120 6.16 1.84 1.00 0.22 6.60E.Q4 _1_1_ 0",
,.20 -s ..3ti l.tiOE·1>I _ _ 1_ ..,IVIOI
7520 ·9.11 i.tiOE·1>I __ 1_ ..,IVIO'
.7.62.0 .... 1.6OE.Q4 _ _ 1_ .OIVIOI
7820 13.60 1.6OE.Q4 _ _1_ 'OIVIO!
7920 6.23 1.81 14.56 Il U.out:·... 1_ IOlVlO!
..,20 G.Z' Z.1' r."" U. U.out:..... __ 1_ IIOIVIO!
8120 8.25 ~38 4.e. 022 6.6OE.Q4 __ 1_ WIV/OI
8420 6.29 2.03 -3.48 0.22 8.6OE·1>I ", __ 1_ "OIVIOI
8520 6.3 2.03 US 0.22 6.6OE·04 __ 1_ IOIVIO!
8640 6.31 27;8 6.60E.Q4 I'll" _ _ JOIVlO!
8700 6.32 53)9 6.6OE.Q4 "''' _ _ OIV/OI
8760 6.33 81!3 6.6OE.Q4 ".,. - r.II## 1j)1V/O!
8190 6.33 12 53 8.6OE.Q4 "',. _ ,.,.. IOIVJOt
8840 6.304 56 Z4 8.6OE·04 ".,. _ ... IOIVIO'
8890 6.35 3.s9 -2727 0 19 6.6OE~ l1li__ 1_ 1JOIVIOI
8940 8.36 2.62 "'7.30 0.19 6.6OE.04 l1li_1_ 1_ 4IOIVJOI
8990 .8.37 .76 "'.66 019 6.6OE.04 l1li_1_1_ 1J01VIO!
9140 8.37 1.43 -0.119 0.19 8.6OE-04 __ 1_1_ 'lDIVJOI
10440 6.•9 2.28·1. 1.19 11# <ml i- lfl"V~
11540 6.61 3.22 ·15.45 0.19 .6OE-tl4 1_1__
11640 U2 Z.... I ·2'." 0 ,. . G.!!Ot:-U4 1_1_ •_ .OIVIOI
'12040 6.65 2.45 0.&3 0.19 6.6OE-04 1_1_ _ 'OIVIOI
12140 s, 66 2.30 ""'b U.lV ti.tiUt·1>I 1_1_ _ .uIV/O'
12340 6.67 ~04 5.68 019 6.6OE~ 1__ 1__ '01\'101
12440 6.68 5.54 0.19 6.6OE·04 1 __ 1_ _ IDI\'IO!
12540 6.69 2.23 ....73 0.19 MOE.~ 1_1__ *DlVIOI
12640 6.7 2.06 -9.47 U.I. ti.tillt-'" 1 WIV~
12840 6.' tOl 9.e' 0 19 6.6OE~ 1_ _ _ IDIV~
12960 6. .23 18.66 019 6..6OE·04 1" "OIV~
13020 6.72 2.55 4l.87 0.19 6.6OE·04 11l1_li IDIV~13080 6.73 3.23 tie.ti~ u rs O.!!Ot:-oo. ,__ ..,IVNI

Fe-METHOD: Estimation of the sustainable yield of a borehole
BH403
Extrapolation time in years =_(enter) 2 1051200 Extrapol.time in minules
Effective borehole radius (r.) - (enier) 0.30 ..- #NUMI f-- Est. r, From r(e) sheet
Q (Vs) from pumping lest - 0.05 3.52E-03 ..f-- S-Iate +-I-- Change rs (available drawdown), sigma s - (enter) 11.4 - Sigma_s from risk
Annual effective recharge (mm) - 11.43 s_available working drawdown(m)
l(end) and s(end) of pumping test - 14960
Average maximum derivalive - (enier) 5.5 .•..
6.88 End lime and drawdown of lest
- 5.5 Estimate of average of max deriv
Average second derivative - (enter) 1.0 - 1.0 Estimate of average second deriv
Derivative at radial flow period - (enier) #NUMI .. _ #NUMI Read from derivative graph
T.early[m Id]- #NUMI Aqui. truck (m) 6
Tand S estimates from derivatives T-Iate [m-Id] - 0.14 Est. S-Iate = 3.30E-04
(To ootam correct S-value, use program RPTSOLV) s-tate - 6.60E-04 S·estlmate could be wrong
BASIC SOLUTION
(Using derivatives + SUbjective information about boundaries) Maximum influence of boundaries at long time
(No values of Tand S are necessary) No boundaries 1 no-flow 2 no-flow Closed no-flow
sWell (Extrapol.tlme) -I 18.73 28.90 39.08 69.60
Q_sust (lis) = 0.03 0.02 0.01 0.01
Best case Worst case
Average Q_sust (lIs) =1 0.02
with standard deviation= 0.01 I
(If no information exists about boundaries Skip advanced solulion and go to final recommendation)
ADVANCEDSOLUTION
(Using derivatives+ knowtedge on boundaries and other bore holes )
(Late T-and S-values a priori + dislance to boundary)
T -late [m2/dJ - (enter) ___,. 0.14
s-tate - (enter) --+ 1.00E-03
1. BOUNDARY INFORMATION (choose a or b) (Code -9999 = dummy value if not applicable)
(a) Barrier (no-flow) boundaries --+ Closed Square ISingle Barrier Intersect. 90u 2 Parallel Barners
Bound. distance a[meter] : (enter) 9999 I 9999 9999 9999
Bound. distance b[meter] : (enter) 9999 9999
s_Bound(t = Extrapol.time) [m] = #NUMI #NUMI #NUMI #NUMI
(b) Fix head boundary + no-flow ~ Closed Fix Single Fix 90 Fix"'no-now /I Fix+no-flow
Bound. distance to fix head a[meter] : (enter) 9999 9999 9999 9999
Bound. distance to no-flow b[meter] : (enter) 9999 9999
s_Bound(t = ExtrapoLlime) [m] = #NUMI #NUMI #NUMI #NUMI
2. INFLUENCE OF OTHER BORE HOLES --+ Q (Us) r tm) u r W(u,r)
BH1 O.OOE+OO #NUMI
BH2 O.OOE+OO #NUMI
s_(lnfluence of BH1,BH2)" 0.00 0.00 2.15E-07 14.78
SOLUTION INCLUDING BOUNDS AND BH's
Fix head + No-flow: Q_sust (lIs) = 9999.00 9999.00 9999.00 9999.00
No-flow: Q_sust (lis) = 9999.00 9999.00 I 9999.00 9999.00
EnterselectedQ for risk analysis = (enter) -+ Sigma_s = 0.000
(Go to Risk sheet and perform risk analysis from which sigma s will be estimated: only for barrier boundaries)
FINAL RECOMMENDEDABSTRACTION RATE
Abstraction rate (115) for 24 hrld = (enter)
Total amount of water allowed to be
abstracted per month (mJ)= 0
COMMENTS
Q_sust with 68% safety =
Q_sust with 95% safety =
APPENDIX D
Groundwater level monitoring results
Parameter Groundwater level (rnbql)"
Borehole number
BH1 BH2 BH3 BH4 BH5 BH6 BH7 BH8 BH9 BH10 BH11 BH12 BH13 BH14 BH15 BH16 BH17 BH18 BH19 BH20 BH21
Monitoring date
2004/12/06 2.224 2.115 2.136 1.348 2.527 2.123 2.94 1.697 2.43 2.154 2.417 1.78 1.63 1.647 1.158 0.863 1.798 2.681 2.835 3.503 #N/A
2005/01/03 2.178 1.912 2.09 2.252 2.449 2.967 1.48 1.512 2.096 2.039 2.346 1.685 1.563 1.625 1.187 0.744 1.745 2.678 2.804 3.479 #N/A
2005/02/07 2.157 1.967 2.062 2.233 2.471 #N/A 1.51 1.556 2.134 1.986 2.292 1.687 1.634 1.709 1.268 0.923 1.642 2.707 2.842 3.462 1.519
2005/03/07 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2005/04/04 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2005/05/03 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2005/06/06 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2005/07106 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A 2.256 2.126 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2005/08/02 2.76 2.145 2.122 2.31 2.632 #N/A 1.72 1.754 2.289 2.184 2.525 1.525 1.7 1.685 1.316 0.84 1.81 2.823 2.916 2.551 1.637
2005/09/12 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A 2.365 2.268 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2005/10107 2.277 2.205 2.181 2.459 2.621 #N/A 1.82 1.763 2.351 2.259 2.652 1.684 1.849 1.826 1.386 0.819 1.866 2.775 2.898 3.595 1.534
2005/11/09 1.285 #N/A #N/A 2.509 #N/A #N/A #N/A 1.629 2.232 #N/A #N/A 1.638 #N/A #N/A #N/A #N/A 1.869 2.755 2.863 3.587 #N/A
2005/12/05 1.234 #N/A #N/A 2.418 #N/A #N/A #N/A 1.679 2.287 #N/A #N/A 1.629 #N/A #N/A #N/A #N/A 1.871 2.775 2.899 3.591 #N/A
2006/01/16 2.127 #N/A #N/A 1.894 #N/A #N/A #N/A 1.579 2.197 #N/A #N/A 1.601 #N/A #N/A #N/A #N/A 1.852 2.617 2.779 3.516 #N/A
2006/02/13 2.074 #N/A #N/A 1.843 #N/A #N/A #N/A 1.652 2.269 #N/A #N/A 1.614 #N/A #N/A #N/A #N/A 1.422 2.761 2.862 3.586 #N/A
2006/03/13 1.181 #N/A #N/A 2.271 #N/A #N/A #N/A 1.031 1.872 #N/A #N/A 0.865 #N/A #N/A #N/A #N/A 1.671 2.346 2.546 2.962 #N/A
2006/04/11 2.039 #N/A #N/A 2.114 #N/A #N/A #N/A 1.585 2.02 #N/A #N/A 1.264 #N/A #N/A #N/A #N/A 1.519 2.549 2.758 3.105 #N/A
2006/05/08 2.126 #N/A #N/A 2.106 #N/A #N/A #N/A 1.284 2.039 #N/A #N/A 1.259 #N/A #N/A #N/A #N/A 1.497 2.451 2.664 3.071 #N/A
2006/06/06 2.072 #N/A #N/A 1.871 #N/A #N/A #N/A 1.442 2.142 #N/A #N/A 1.346 #N/A #N/A #N/A #N/A 1.557 2.524 2.697 3.018 #N/A
2006/07/10 2.174 2.056 1.987 2.291 2.358 1.969 1.67 1.713 2.383 2.394 2.515 1.599 1.589 1.806 1.984 0.82 1.701 2.68 2.831 3.181 2.02
2006/08/21 2.312 #N/A #N/A 2.454 #N/A #N/A #N/A 1.808 2.489 #N/A #N/A 1.507 #N/A #N/A #N/A #N/A 1.709 2.675 2.835 3.397 #N/A
2006/09/18 2.186 #N/A #N/A 2.309 #N/A #N/A #N/A 2.351 2.398 #N/A #N/A 1.438 #N/A #N/A #N/A #N/A 1.647 2.641 2.808 3.238 #N/A
2006/10104 2.169 #N/A 1.864 #N/A #N/A #N/A #N/A #N/A 2.397 #N/A #N/A 1.442 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2006/11/06 1.993 #N/A 1.761 #N/A #N/A #N/A #N/A #N/A 2.037 #N/A #N/A 1.719 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2006/12/04 1.751 #N/A 1.461 #N/A #N/A #N/A #N/A #N/A 1.774 #N/A #N/A 0.938 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2007101/03 1.27 #N/A #N/A 1.82 #N/A #N/A #N/A 0.81 1.679 #N/A #N/A 0.775 #N/A #N/A #N/A #N/A 1.81 2.689 2.555 2.905 #N/A
2007102/05 2.131 #N/A 1.942 #N/A #N/A #N/A #N/A #N/A 2.172 #N/A #N/A 1.403 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2007/03/07 2.005 #N/A 1.863 2.025 #N/A #N/A #N/A 1.19 2.065 #N/A #N/A 1.215 #N/A #N/A #N/A #N/A 1.469 #N/A #N/A 3.045 #N/A
2007/04/03 1.865 #N/A 1.368 #N/A #N/A #N/A #N/A #N/A 1.994 #N/A #N/A 0.952 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2007/05/09 1.693 #N/A #N/A 1.96 #N/A #N/A #N/A #N/A #N/A #N/A #N/A 1.06 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2007/06/04 1.928 #N/A #N/A #N/A #N/A #N/A #N/A #N/A 1.645 #N/A #N/A 1.518 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2007/07102 1.928 #N/A #N/A #N/A #N/A #N/A #N/A #N/A 1.954 #N/A #N/A 1.558 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2007/08/06 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A 2.341 #N/A #N/A 1.56 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2007/09/17 #N/A #N/A #N/A 2.332 #N/A #N/A #N/A 1.814 2.614 #N/A #N/A 1.594 #N/A #N/A #N/A #N/A 1.784 #N/A #N/A #N/A #N/A
2007/11/05 1.324 #N/A #N/A 1.801 #N/A #N/A #N/A #N/A 1.825 #N/A #N/A 0.847 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2007/12/10 1.105 1.427 1.326 1.554 #N/A 1.175 0.49 0.709 1.634 1.885 2.498 0.634 0.864 1.011 0.714 0.546 0.851 #N/A #N/A 2.586 1.465
2008/02/01 #N/A 1.744 #N/A #N/A #N/A 1.916 #N/A 1.312 2.015 1.873 2.178 #N/A 1.169 #N/A #N/A #N/A #N/A #N/A #N/A #N/A 1.791
2008/04/03 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A 2.127 1.211 1.092 #N/A 0.934 0.561 #N/A #N/A #N/A #N/A #N/A
2008/07/14 .... #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A 1.803 1.054 1.025 #N/A 0.774 0.596 #N/A #N/A #N/A #N/A #N/A
N/A = Not available
Parameter Groundwater level(mbgl)'
Borehole number BH22 BH23 BH24 BH25 BH26 BH27 BH28 BH29 BH30 BH31 BH32 BH33 BH34 BH35 BH36 BH37 BH38 BH39 BH40
Monitoring date
2004/12/06 #N/A #N/A 0.893 1.062 1.134 1.669 1.668 2.354 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2005/01/03 #N/A #N/A 0.842 1.033 1.038 1.489 1.516 2.302 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2005/02/07 1.519 1.015 0.929 1.091 1.167 1.624 1.643 2.253 1.531 1.488 1.151 1.311 1.312 0.603 #N/A #N/A #N/A #N/A #N/A
2005/03/07 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A 1.173 0.945 1.193 1.027 0.503 2.197 1.837 1.863 #N/A #N/A
2005/04/04 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2005/05/03 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2005/06/06 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2005/07/06 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2005/08/02 1.637 1.11 0.99 1.203 1.185 1.631 1.666 2.261 1.562 1.621 1.209 1.405 1.358 0.526 2.4 1.975 2.047 2.211 #N/A
2005/09/12 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2005/10107 1.534 0.985 0.987 1.306 1.245 1.802 1.799 2.495 1.665 1.493 1.146 1.228 1.236 0.492 2.431 1.992 2065 #N/A #N/A
2005/11/09 #N/A 0.964 #N/A #N/A 1.194 #N/A #N/A #N/A #N/A #N/A 1.002 1.208 1.905 0.475 2.408 #N/A #N/A #N/A #N/A
2005/12/05 #N/A 0.936 #N/A #N/A 1.201 #N/A #N/A #N/A #N/A #N/A 1 1.201 1.899 0.472 2.406 #N/A #N/A #N/A #N/A
2006/01/16 #N/A 0.899 #N/A #N/A 1.181 #N/A #N/A #N/A #N/A #N/A 0.989 1.119 1.887 0.451 2.382 #N/A #N/A #N/A #N/A
2006/02/13 #N/A 0.784 #N/A #N/A 1.201 #N/A #N/A #N/A #N/A #N/A 0.863 1.117 1.828 0.409 2.396 #N/A #N/A #N/A #N/A
2006/03/13 #N/A 0.721 #N/A #N/A 1.002 #N/A #N/A #N/A #N/A #N/A 0.971 1.012 1.622 0.217 1.948 #N/A #N/A 1.917 #N/A
2006/04/11 #N/A 0.932 #N/A #N/A 0.971 #N/A #N/A #N/A #N/A #N/A 1.106 1.226 1.252 1.364 2.396 #N/A #N/A #N/A #N/A
2006/05/08 #N/A 0.846 #N/A #N/A 0.989 #N/A #N/A #N/A #N/A #N/A 1.109 1.178 1.369 1.401 2.139 #N/A #N/A #N/A #N/A
2006/06/06 #N/A 0.885 #N/A #N/A 0.959 #N/A #N/A #N/A #N/A #N/A 0.991 1.246 1.158 0.449 2.184 #N/A #N/A #N/A #N/A
2006/07/10 0.986 0.971 0.916 0.987 1.549 1.583 1.558 1.705 1.419 1.525 1.238 1.323 1.321 0.529 2.23 2.016 1.947 #N/A #N/A
2006/08/21 #N/A 0.949 #N/A #N/A 1.098 #N/A #N/A #N/A #N/A #N/A 1.051 1.288 1.16 0.453 2.304 #N/A #N/A #N/A #N/A:
2006/09/18 #N/A 0.857 #N/A #N/A 1.065 #N/A #N/A #N/A #N/A #N/A 0.964 1.176 1.053 0.426 2.306 #N/A #N/A 1.963 #N/A
2006/10104 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2006/11/06 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A I
2006/12/04 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2007101/03 #N/A 0.885 #N/A #N/A 0.799 #N/A #N/A #N/A #N/A #N/A 0.885 #N/A 0.94 0.39 1.81 #N/A #N/A 1.739 #N/A
2007102/05 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2007103/07 #N/A 0.975 #N/A #N/A 0.919 #N/A #N/A #N/A #N/A #N/A 1.05 1.115 0.96 0.478 2.19 #N/A #N/A 1.89 #N/A
2007104/03 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2007105/09 #N/A 1.009 #N/A #N/A 0.884 #N/A #N/A #N/A #N/A #N/A 1.162 #N/A 1.174 0.513 1.88 #N/A #N/A 1.75 #N/A
2007106/04 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2007107102 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2007108/06 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2007109/17 #N/A 1.084 #N/A #N/A 2.371 #N/A #N/A #N/A #N/A #N/A 1.23 1.251 1.176 0.389 2.4 #N/A #N/A #N/A #N/A
2007/11/05 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2007/12/10 1.221 0.835 0.453 0.378 0.726 0.97 0.816 1.097 0.364 0.691 0782 1.077 1.008 0.428 1.854 1.525 1.574 1.679 #N/A
2008/02/01 1.607 #N/A 0.686 #N/A 0.926 #N/A #N/A #N/A 0.771 #N/A 1.193 #N/A 1.425 #N/A #N/A #N/A #N/A 1.874 #N/A
2008/04/03 #N/A #N/A 0.57 0.739 0.943 #N/A #N/A #N/A 0.838 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2008/07/14 #N/A #N/A 0.534 0.672 0.836 #N/A #N/A #N/A 0.735 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
N/A = Not available
Parameter Groundwater level (mbgl)*
Borehole number
BH10l BH102 BH103 BH104 BH105 BH106 BH107 BH108 BH109 BHll0 BHlll BHl12 BHl13 BHl14 BHl15 BHl16 BHl17 BHl18 BHl19 BH120 BH121
Monitoring date
2004/12/06 1.429 0.062 1.632 2.882 2.128 3.384 0.628 1.462 1.741 1.657 2.623 1.326 1.094 1.479 1.381 0.851 0.711 0.726 1.143 2.294 0.997
2005/01/03 1.346 0.01 1.57 2.798 2.103 3.337 #N/A 1.389 1.607 1.467 2.577 1.118 0.908 1.391 1.204 #N/A #N/A #N/A #N/A 2.249 0.725
2005/02/07 1.368 0 1.579 2.817 2.169 3.372 0.588 1.431 1.615 1.278 2.389 1.095 0.946 1.317 1.21 0.821 0.692 0.72 1.152 2.235 0.889
2005/03/07 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2005/04/04 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2005/05/03 #N/A #N/A #N/A 2.795 #N/A #N/A 0.533 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2005/06/06 #N/A #N/A #N/A 2.86 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2005/07/06 #N/A #N/A #N/A 2.835 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2005/08/02 1.635 0 1.525 2.792 2.085 3.568 0.745 1.582 1.718 #N/A 2.682 1.381 1.17 #N/A 1.456 0.912 0.859 0.775 1.216 2.344 0.927
2005/09/12 #N/A #N/A #N/A 2.643 #N/A #N/A 0.671 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2005/10107 1.713 0 1.599 2.816 2.031 3.686 0.641 1.459 1.337 #N/A 1.942 1.487 1.347 1.596 1.661 0.796 0.817 0.706 1.229 2.339 0.995
2005/11/09 #N/A 0 1.551 2.772 #N/A 3.693 0.529 1.145 1.886 1.669 3.007 #N/A 1.346 #N/A 1.194 #N/A #N/A 0.632 1.216 1.414 1.01
2005/12/05 #N/A 0 1.55 2.917 2.036 3.685 0.503 1.152 1.889 #N/A 3 #N/A 1.329 #N/A 1.191 #N/A #N/A 0.63 1.219 1.401 1.01
2006/01/16 #N/A 0 1.506 2.916 1.264 3.682 0.516 1.121 1.795 1.629 2.997 #N/A 1.321 #N/A 1.184 #N/A #N/A 0.619 1.197 1.362 0.997
2006/02/13 #N/A 0 1.462 2.652 2.019 3.616 0.329 0.919 1.881 1.652 2.998 #N/A 1.316 #N/A 1.182 #N/A #N/A 0.482 0.936 2.233 0.685
2006/03/13 #N/A 0 1.782 1.961 1.971 3.189 0 1.042 1.116 1.271 1.454 #N/A 1.269 1.481 1.162 #N/A #N/A 0.512 1.146 1.521 1.187
2006/04/11 #N/A 0 1.428 2.624 0.863 3.401 0.01 1.251 1.099 1.134 1.164 #N/A 1.876 #N/A 0.174 #N/A #N/A 0.996 0.942 2.04 0.659
2006/05/08 #N/A 0 1.516 2.268 0.896 3.359 0.06 1.172 1.11 1.159 1.216 #N/A 1.899 #N/A 0.206 #N/A #N/A 1.006 1.001 2.02 0.598
2006/06/06 #N/A 0.04 1.425 2.764 #N/A 3.267 0.07 1.231 0.942 1.029 1.724 #N/A 0.634 #N/A 0.886 #N/A #N/A 0.622 0.891 2.051 0.664
2006/07/10 1.653 0.026 2.119 2.562 #N/A 3.465 0.023 1.429 0.997 1.274 1.643 1.599 1.368 #N/A 1.235 0.876 0.794 0.715 1.029 2.659 2.806
2006/08/21 #N/A 0.004 1.545 2.899 #N/A 3.058 0.541 1.427 #N/A 1.248 2.469 #N/A 0.941 1.138 1.234 #N/A #N/A 0.661 1.031 2.154 0.802
2006/09/18 #N/A 0 1.521 2.85 #N/A 3.42 0.391 1.314 1.299 1.175 2.453 #N/A #N/A #N/A 1.103 #N/A #N/A 0.665 0.99 2.14 0.634
2006/10104 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2006/11/06 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2006/12/04 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2007/01/03 #N/A 0 1.22 2.54 1.48 2.889 0 0.852 0.459 0.69 1.095 #N/A #N/A #N/A 0.558 #N/A #N/A 0.686 0.639 1.645 0.405
2007/02/05 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2007/03/07 #N/A 0 1.41 2.675 1.678 2.948 0 1.209 0.756 0.77 1.87 #N/A #N/A #N/A 0.786 #N/A #N/A 0.548 0.82 1.91 0.658
2007/04/03 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2007/05/09 #N/A 0 1.23 2.71 1.602 2.62 0 1.125 0.514 0.995 1.259 #N/A #N/A 1.248 0.778 #N/A #N/A 0.65 0.714 1.553 0.334
2007/06/04 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2007/07/02 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2007/08/06 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2007/09/17 #N/A #N/A #N/A 2.803 #N/A #N/A 0.396 1.376 #N/A #N/A #N/A #N/A #N/A #N/A 0.826 #N/A #N/A 0.69 #N/A #N/A #N/A
2007/11/05 #N/A #N/A #N/A 1.347 #N/A #N/A 0 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2007/12/10 0.67 0 1.099 1.234 1.413 2.396 0 0.555 0.337 0.724 0.985 0.276 #N/A #N/A 0.603 1.004 0.411 0.478 0.523 1.145 0.01
2008/02/01 1.223 0 1.295 #N/A 1.64 #N/A #N/A #N/A 0.612 1.015 #N/A 0.487 #N/A #N/A #N/A #N/A 0.498 #N/A #N/A #N/A #N/A
2008/04/03 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A 0.885 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2008/07/14 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A 0.559 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
N/A = Not available
mbgl = metres below ground level
I
Parameter Groundwater level (mbgl)*
Borehole number
BH201A BH202A BH20JA BH206A BH208A BH211A BH212A BH214A BH217A BH218A BH220A BH221A
Monitoring date
2004/12/06 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2005/01/03 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2005/02/07 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2005/03/07 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2005/04/04 #N/A #N/A 0.894 0 #N/A #N/A 2.072 #N/A #N/A #N/A #N/A #N/A
2005/05/03 #N/A #N/A 1.088 0.774 1.605 1.114 2.031 #N/A 1.769 1.361 #N/A 1.512
2005/06/06 1.416 1.695 1.156 1.63 1.442 0.938 2.032 1.926 1.906 1.469 1.249 1.659
2005/07/06 1.075 1.258 1.178 1.693 1.325 0.924 2065 1.589 1.923 1.479 0.685 1.714
2005/08/02 1.47 1.275 1.226 1.831 1.454 0.96 #N/A 1.618 1.945 1.51 0.739 1.736
2005/09/12 1.149 1.265 1.166 1.958 1.442 0.862 #N/A 1.631 1.899 1.465 0.7 1.836
2005/10/07 1.074 1.344 1.084 1.951 1.541 0.877 #N/A 1.619 1.872 1.416 0.701 1.841
2005/11/09 #N/A #N/A 1.269 1.962 1.534 0.832 4.514 1.848 1.815 1.372 0.649 1.849
2005/12/05 #N/A 1.498 1.214 1.875 1.526 0.852 3.096 1.801 1.889 1.462 0.647 1.846
2006/01/16 #N/A #N/A 1.27 1.909 1.589 0.814 5.432 1.865 1.779 1.364 0.565 1.61
2006/02/13 #N/A #N/A 1.101 1.692 1.459 0.662 #N/A 1.701 1.596 1.197 0.444 1.846
2006/03/13 #N/A #N/A 1.082 1.118 1.102 0.581 9.51 1.609 1.524 1.301 0 1.162
2006/04/11 0.928 #N/A #N/A 1.34 1.189 0.714 #N/A 1.903 1.738 0.326 0.502 1.579
2006/05/08 #N/A #N/A 1.156 1.368 1.101 0.581 #N/A 1.784 1.681 1.269 0.396 1.681
2006/06/06 #N/A #N/A 1.185 1.416 1.214 0.762 #N/A 2.069 1.734 1.314 0.476 1.549
2006/07/10 1.144 1.185 1.384 1.679 1.355 0.879 #N/A 1.928 1.878 1.435 0.615 1.45
2006/08/21 #N/A #N/A 1.171 1.799 1.387 0.833 2.965 2.093 1.848 1.391 0.591 1.789
2006/09/18 #N/A #N/A 1.038 1.831 1.368 0.76 #N/A 1.714 1.752 1.308 0.542 1.752
2006/10/04 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2006/11/06 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2006/12/04 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2007/01/03 #N/A #N/A 0.68 0.855 1.042 0.715 #N/A 1.472 1.579 1.16 0.309 #N/A
2007/02/05 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2007/03/07 #N/A #N/A 0.755 1.345 1.2 0.95 #N/A 1.739 1.762 1.365 0 1.513
2007/04/03 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2007/05/09 #N/A #N/A 0.76 1.11 1.17 1.06 #N/A 1.61 1.81 1.4 0.426 #N/A
2007/06/04 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2007/07/02 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2007/08/06 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2007/09/17 1.098 #N/A 1.085 2013 1.335 1.114 #N/A 1.799 1.938 1.51 0.654 1.786
2007/11/05 0.91 #N/A 0.623 1.762 1.057 0.395 #N/A 1.196 1.595 1.118 #N/A #N/A
2007/12/10 0.854 0.773 0.516 0.944 0.955 0.956 #N/A 1.168 1.476 1.328 0.355 0.856
2008/02/01 0.897 0.973 0.514 #N/A #N/A #N/A #N/A #N/A #N/A 1.494 #N/A 1.44
2008/04/03 #N/A #N/A #N/A 1.234 1.218 #N/A #N/A #N/A #N/A #N/A #N/A 1.294
2008/07/14 #N/A #N/A #N/A 1.025 1.199 #N/A #N/A #N/A #N/A #N/A #N/A 1.322
N/A = Not available
mbgl = metres below ground level
Parameter Groundwater level (rnbql)"
Borehole number BH201 BH202 BH203 BH205 BH206 BH208 BH209 BH210 BH211 BH213 BH214 BH216 BH217 BH218 BH219 BH220 BH221 BH222 BH223
Monitoring date
2004/12/06 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2005/01/03 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2005/02/07 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2005/03/07 0.694 1.012 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2005/04/04 0.828 0.948 OA06 2.859 0.515 0.967 OA68 0.383 0 2.861 2.505 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2005/05/03 0.935 1.012 OA65 2.99 1.868 1.196 0.62 0.581 0 2.913 2.538 2.571 1A18 0.952 #N/A 0 1.349 1.619 #N/A
2005/06/06 1.035 1.126 0.547 3.05 0.779 1.338 0.715 0.726 1.56 3.003 2.671 2.655 1.5 1.035 2Al 1.15 lA79 1.734 1.21
2005/07/06 1.065 1.204 0.617 3.005 0.83 1.294 0.647 0.716 OA45 3.035 2.677 2.655 lA98 1.019 2A07 0.3 lA72 1.747 0.543
2005/08/02 1.119 1.279 0.675 3.085 0.923 lA07 0.767 0.785 0.511 3.089 2.701 2.71 1.565 1.075 2A45 0.359 1.544 1.83 0.59
2005/09/12 1.158 1.329 0.748 3.164 1.022 1.398 0.756 0.772 0.501 3.069 2.759 2.703 1.542 1.081 2A53 0.385 1.583 1.849 0.531
2005/10/07 1.11 1.262 0.74 3.217 1.025 1.463 #N/A 0.786 OA95 3.135 2.778 2.747 1.573 1.076 2A71 OA03 1.582 1.864 0.532
2005/11/09 1.321 1.857 1.521 3.286 1.145 lA52 #N/A 0.755 OA94 3.105 2.899 2.714 1.556 1.067 2A49 0.384 1.592 1.864 OA57
2005/12/05 1.271 1.799 lA98 3.001 1.099 lA06 #N/A 0.757 OA69 3 2.951 2.701 1.762 1.056 2A48 0.371 1.59 1.864 OA52
2006/01/16 1.212 1.875 1.742 3.187 1.876 1Al #N/A 0.628 OA73 3.099 2.945 2.573 1.57 1.024 2.369 0.36 lA41 1.709 OA46
2006/02/13 1.171 1.779 1.675 3.045 0.944 1.309 #N/A 0.749 0.256 2.956 2.746 2A53 1.258 0.895 2.169 0.195 1.586 1.859 0.285
2006/03/13 1.121 1.633 1.641 2.995 0.522 1.02 #N/A 0.517 0.09 2.713 2.611 2.614 1.102 0.801 2.271 0 1.017 1.016 0.341
2006/04/11 1.148 1.524 1.371 2.872 0.681 1.089 #N/A 0.464 0.324 2.761 2.823 2A99 1.307 0.849 2.261 0.01 1.351 1.639 0.956
2006/05/08 1.096 1.521 1.169 2.991 0.561 1.026 #N/A 0.516 0.189 2.754 2.617 2.386 1.25 0.817 2.289 0 1.529 1.587 0.991
2006/06/06 1.119 1.331 0.994 2.931 0.714 1.137 #N/A 0.542 0.389 2.653 2.831 2.538 1.385 0.843 2.194 0 1.314 1.584 0.37
2006/07/10 1.132 1.295 0.917 2.986 0.941 1.271 #N/A 0.705 OA82 3.002 2.827 2.664 1.545 0.982 2.375 0.22 1.805 1.723 OA92
2006/08/21 1.099 1.326 0.813 3.079 0.956 1.324 #N/A 0.664 OA37 3.032 2.965 2.632 1A73 0.982 2.319 0.254 1A63 1.728 OA46
2006/09/18 1.032 1.225 0.667 3.075 0.882 1.272 #N/A 0.625 0.376 2.959 2.996 2.575 1All 0.934 2.244 0 1.397 1.689 0.395
2006/10/04 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2006/11/06 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2006/12/04 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2007/01/03 0.797 1.112 #N/A #N/A OA8 0.95 #N/A 0.37 0.22 #N/A 2.979 2A85 1.23 0.761 1.964 0 #N/A 1.493 0.259
2007/02/05 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2007/03/07 0.825 1.105 0.579 2.87 0.65 1.119 #N/A 0.535 0.33 #N/A 1.575 2A45 1.328 0.85 2.145 0 1.523 1.528 0.387
2007/04/03 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2007/05/09 #N/A 0.966 #N/A #N/A 0.62 1.01 #N/A 0.305 0.305 #N/A 2A93 2.384 1.275 0.795 2.015 0 #N/A lA35 OA68
2007/06/04 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2007/07/02 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2007/08/06 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2007/09/17 1.219 #N/A #N/A #N/A 1.105 1.29 #N/A #N/A 0.541 #N/A 2.635 2.661 1.552 1.097 2.281 0.224 #N/A #N/A 0.568
2007/11/05 #N/A #N/A #N/A #N/A 0.563 0.915 0.394 #N/A 0 #N/A 2.114 #N/A 1.137 0.674 #N/A 0 #N/A #N/A #N/A
2007/12/10 0.786 0.945 #N/A #N/A OA3 0.825 0.375 0.37 0 #N/A 2.143 2.257 1.134 1.114 1.956 0 0.826 1.654 0.631
2008/02/01 0.834 1.008 #N/A #N/A #N/A 1.095 0.54 0.562 0.373 #N/A #N/A 2A03 #N/A 0.862 2.086 0 1.02 1.32 #N/A
2008/04/03 #N/A #N/A #N/A #N/A 0.506 1.096 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A 1.097 1.327 #N/A
2008/07/14 #N/A #N/A #N/A #N/A OA24 1.068 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A 1.119 1.324 #N/A
N/A = Not available
mbgl = metres below ground level
Parameter Groundwater level (mbglr
Borehole number
BH301 BH302 BH303 BH304 BH307 BH308 BH309 BH310 BH311 BH312 BH313 BH314 BH315 BH316 BH317 BH318
Monitoring date
2004/12/06 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2005/01/03 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2005/02/07 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2005/03/07 #N/A 0.597 0.57 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2005/04/04 0 0.51 0.382 1.354 0.61 1.546 1.755 2.067 1.713 1.896 2.201 2.455 2.651 1.584 1.762 1.172
2005/05/03 0.399 0.798 0.64 1.519 0.869 1.676 1.801 2.174 1.775 1.896 2.29 2.547 2.689 1.929 1.885 1.169
2005/06/06 0.625 0.92 2.039 1.556 0.973 1.77 1.937 2.347 1.885 1.976 2.418 2.622 2.793 2.116 1.959 1.505
2005/07/06 #N/A 0.952 0.809 1.617 1.023 1.875 2.039 2.435 1.935 2.065 2.472 2.666 2.835 2.223 2.013 1.479
2005/08/02 0.762 0.997 0.892 #N/A 1.055 1.886 2.079 2.479 1.971 2.059 2.512 2.679 2.875 #N/A 2.03 1.496
2005/09/12 0.636 0.959 0.852 1.676 0.932 1.917 1.995 2.491 1.995 2.079 2.548 2.702 2.857 3.321 2.074 1.465
2005/10/07 #N/A 0.903 0.805 1.661 0.851 1.924 1.998 2.493 1.993 2.075 2.516 2.684 2.845 2.342 2.085 1.556
2005/11/09 #N/A 0.872 0.775 #N/A 0.856 #N/A 2.502 #N/A #N/A 2.106 #N/A 2.575 2.815 2.403 #N/A 1.452
2005/12/05 #N/A 0.852 0.723 #N/A 0.941 #N/A 2.439 #N/A #N/A 2.069 #N/A #N/A 2.809 2.374 #N/A 1.439
2006/01/16 #N/A 0.637 0.739 #N/A 0.789 #N/A 2.389 #N/A #N/A 2.091 #N/A 2.547 2.719 2.356 #N/A 1.343
2006/02/13 #N/A 0.569 0.519 #N/A 0.692 #N/A 2.356 #N/A #N/A 1.99 #N/A 2.487 2.664 1.681 #N/A 1.248
2006/03/13 #N/A 0.617 0.511 #N/A 0.721 #N/A 2.209 #N/A #N/A 1.893 #N/A 2.417 2.518 1.401 #N/A 1.307
2006/04/11 #N/A 0.613 0.481 1.697 0.693 1.952 2.487 #N/A 1.903 1.914 #N/A 2.487 2.708 1.712 #N/A 1.29
2006/05/08 #N/A 0.619 0.561 #N/A 0.829 #N/A 2.581 #N/A #N/A 2.164 #N/A 2.519 2.695 2.001 #N/A 1.287
2006/06/06 #N/A 0.694 0.59 #N/A 0.968 #N/A 2.59 #N/A #N/A 2.152 #N/A 2.564 #N/A 1.904 #N/A 1.327
2006/07/10 #N/A 0.81 0.855 1.921 1.021 #N/A 2.789 2.659 2.267 NA #N/A 2.651 2.818 2.148 1.97 1.455
2006/08/21 #N/A 0.804 0.695 #N/A 0.91 #N/A 1.574 #N/A #N/A 1.985 #N/A 2.756 2.944 2.355 #N/A 1.394
2006/09/18 #N/A 0.796 0.742 #N/A 0.817 #N/A 1.275 #N/A #N/A 1.803 2.496 2.439 2.864 2.226 #N/A 1.335
2006/10/04 #N/A #N/A #N/A #N/A #N/A 1.371 #N/A #N/A #N/A #N/A #N/A 2.563 #N/A 2.16 1.964 #N/A
2006/11/06 #N/A #N/A #N/A #N/A #N/A 0.884 #N/A #N/A #N/A #N/A #N/A 2.414 #N/A 1.873 1.752 #N/A
2006/12/04 #N/A #N/A #N/A #N/A #N/A 0.667 #N/A #N/A #N/A #N/A #N/A 2.148 #N/A 1.498 1.646 #N/A
2007/01/03 #N/A 0.299 0.22 #N/A 0.317 #N/A 0.575 #N/A #N/A 1.169 #N/A 1.749 1.83 1.219 #N/A 0.97
2007/02/05 #N/A #N/A #N/A #N/A #N/A 1.246 #N/A #N/A #N/A #N/A #N/A 2.418 #N/A 1.993 1.865 #N/A
2007/03/07 #N/A 0.58 0.355 #N/A #N/A 0.859 0.595 #N/A #N/A 1.425 #N/A 2.332 2.644 1.79 #N/A 1.2
2007/04/03 #N/A #N/A #N/A #N/A #N/A 0.79 #N/A #N/A #N/A #N/A #N/A 2.13 #N/A 1.758 #N/A #N/A
2007/05/09 #N/A #N/A 0.569 #N/A 0.59 #N/A 0.999 #N/A #N/A 1.55 #N/A 2.086 2.46 #N/A #N/A #N/A
2007/06/04 #N/A #N/A #N/A #N/A #N/A 1.268 #N/A #N/A #N/A #N/A #N/A 2.504 #N/A 1.964 #N/A #N/A
2007/07/02 #N/A #N/A #N/A #N/A #N/A 1.359 #N/A #N/A #N/A #N/A #N/A 2.067 #N/A 1.822 #N/A #N/A
2007/08/06 #N/A #N/A #N/A #N/A #N/A 0.795 #N/A #N/A #N/A #N/A #N/A 2.558 #N/A 2.089 #N/A #N/A
2007/09/17 #N/A 1.095 0.52 #N/A 0.865 1.183 0.579 #N/A #N/A 1.986 #N/A 2.658 2.91 2.251 #N/A 1.423
2007/11/05 #N/A #N/A 0.507 #N/A #N/A 0.914 0.554 #N/A #N/A 1.114 #N/A 2.047 #N/A 1.168 #N/A #N/A
2007/12/10 0.395 0.854 0 1.41 0.225 0.753 0.23 #N/A 1.146 0.924 1.674 1.916 2.445 1.069 #N/A 0.948
2008/02/01 #N/A 0.715 0.639 1.342 #N/A 0.895 #N/A #N/A 1.29 1.421 #N/A 1.265 2.576 1.764 #N/A 1.114
2008/04/03 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2008/07/14 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
N/A = Not available
mbgl = metres below ground level
Parameter Groundwater level (mbgl)*
Borehole number
BH401 BH402 BH403 BHD1 BHD3 BHD5 BH_T BH_CT BH_C4 BH_DP BH_Ar BH_Ca
Monitoring date
2004/12/06 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2005/01/03 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2005/02/07 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2005/03/07 #N/A #N/A #N/A 7.862 #N/A 2.194 #N/A #N/A #N/A #N/A #N/A #N/A
2005/04/04 #N/A #N/A #N/A 7.793 32.788 2.049 #N/A #N/A #N/A #N/A #N/A #N/A
2005/05/03 #N/A #N/A #N/A 7.519 32.808 1.354 #N/A #N/A #N/A #N/A #N/A #N/A
2005/06/06 #N/A #N/A #N/A 8.242 32.731 2.326 #N/A . #N/A #N/A #N/A #N/A #N/A
2005/07/06 #N/A #N/A #N/A 8.355 32.705 2.717 #N/A #N/A #N/A #N/A #N/A #N/A
2005/08/02 2.626 3.474 2.313 10.466 32.809 2.535 #N/A 0.000 0.871 #N/A 1.495 #N/A
2005/09/12 2.773 2.863 #N/A 8.505 32.747 2.637 #N/A #N/A #N/A #N/A #N/A #N/A
2005/10/07 2.586 2.798 1.947 8.676 32.704 2.492 #N/A 0.000 0.761 #N/A 1.390 #N/A
2005/11/09 2.546 2.654 1.599 8.546 32.686 2.456 #N/A 0 0.764 #N/A 1.579 #N/A
2005/12/05 2.822 2.291 1.997 8.529 32.681 2.185 #N/A 0.000 0.760 #N/A 1.456 #N/A
2006/01/16 2.791 2.751 1.972 8.906 32.791 2.579 #N/A 0.000 0.791 #N/A 1.334 #N/A
2006/02/13 #N/A 2.302 1.526 7.896 32.695 2.334 #N/A 0.000 0.741 #N/A 1.019 #N/A
2006/03/13 2.511 2.131 1.827 7.642 32.694 2.012 #N/A 0.000 0.613 #N/A 0.769 #N/A
2006/04/11 #N/A 2.214 1.692 8.056 32.625 2.147 #N/A 0.000 0.619 #N/A 1.001 #N/A
2006/05/08 #N/A 2.016 1.785 7.995 32.699 1.867 #N/A 0.000 0.583 #N/A 0.989 #N/A
2006/06/06 #N/A 2.026 1.472 7.378 32.594 3.978 #N/A 0.000 0.366 #N/A 0.996 #N/A
2006/07/10 #N/A 2.253 1.551 7.998 32.749 2.227 #N/A 0.000 0.459 #N/A 1.24 #N/A
2006/08/21 #N/A 2.192 1.51 7.861 #N/A 2.087 #N/A 0.000 0.393 #N/A 0.994 #N/A
2006/09/18 2.243 2.253 1.574 7.585 #N/A 2.052 #N/A 0.000 0.000 #N/A 1.195 #N/A
2006/10/04 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2006/11/06 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2006/12/04 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2007/01/03 1.805 1.985 #N/A 7.07 36.07 1.739 #N/A 0.000 0.080 #N/A 0.849 #N/A
2007/02/05 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2007/03/07 2.045 2.289 1.478 7.81 32.37 1.99 0.462 0.000 0.425 #N/A 1.648 #N/A
2007/04/03 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2007/05/09 1.909 2.031 #N/A 7.183 32.164 #N/A 0.506 0.000 0.295 #N/A 0.941 #N/A
2007/06/04 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2007/07/02 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2007/08/06 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2007/09/17 2.274 2.403 #N/A #N/A #N/A 2.197 #N/A #N/A #N/A #N/A #N/A #N/A
2007/11/05 #N/A 2.213 #N/A #N/A #N/A 1.955 #N/A #N/A #N/A #N/A #N/A #N/A
2007/12/10 1.885 2.084 1.361 6.84 31.744 1.824 #N/A 0.000 #N/A 6.045 1.02 0.894
2008/02/01 1.938 2.081 1.415 7.356 31.56 1.831 #N/A #N/A #N/A #N/A #N/A #N/A
2008/04/03 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
2008/07/14 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A
N/A = Not available
mbgl = metres below ground level
APPENDIX E
Analytical results of groundwater samples
Sample type Groundwater chemistry
Aquifer Aquifer 1
Borehole number BH1 BH2 BH3 BH4 BH5 BH11 BH12 BH13 BH14 BH15 BH16 BH17 BH18 BH19 BH20 BH21 BH22
Chemical substance
Sampling Hexavalent chromium concentration (mg/I)
Event Date
1 2004/11/03 342.00 503.00 862.00 269.00 NT NT NT 70.00 936.00 142.00 NT NT NT NT NT 10.40 25.80
2 2005/05/05 321.00 482.00 618.00 NT 0.01 0.01 0.01 60.00 847.00 181.00 0.02 0.03 0.01 0.04 0.84 10.40 23.00
3 2006/02/03 NT NT NT 31.00 NT NT NT NT NT NT NT NT NT NT NT NT NT
4 2006/03/13 279.00 NT 700.00 245.00 NT NT NT NT NT NT NT NT NT NT NT 8.80 14.00
5 2006/04/05 NT NT NT 32.10 NT NT NT NT NT NT NT NT NT NT NT NT NT
6 2006/05/03 306.00 NT 781.00 36.00 NT NT NT NT NT NT NT NT NT NT NT 4.90 21.00
7 2006/06/13 NT NT NT 21.00 NT NT NT NT NT NT NT NT NT NT NT NT NT
8 2006/07/10 140.00 NT 731.00 30.90 <0.02 <0.02 <0.02 74.00 915.00 123.00 <0.02 <0.02 <0.02 <0.02 <0.02 6.00 17.00
9 2006/08/30 292.00 NT 552.00 23.00 NT NT NT NT NT NT NT NT NT NT NT 5.60 24.00
10 2006/09/27 NT NT NT 48.00 NT NT NT NT NT NT NT NT NT NT NT NT NT
11 2006/10/20 278.00 NT 693.00 32.00 NT NT NT NT NT NT NT <0.02 NT NT NT 2.70 19.00
12 2006/11/21 NT NT NT 12.00 NT NT NT NT NT NT NT NT NT NT NT NT NT
13 2006/12/07 260.00 194.00 705.00 7.50 <0.02 <0.02 <0.02 69.00 920.00 129.00 <0.02 <0.02 0.07 <0.02 <0.02 6.60 19.00
14 2007/01/24 270.00 NT 780.00 217.00 NT NT NT NT NT NT NT <0.02 NT NT NT 6.30 NT
15 2007/02/06 NT NT NT 18.00 NT NT NT NT NT NT NT NT NT NT NT NT NT
16 2007/03/22 NT NT 560.00 5.60 NT NT NT NT NT NT NT <0.02 NT NT NT 4.80 8.30
17 2007/04/16 NT NT NT 9.00 NT NT NT NT NT NT NT NT NT NT NT NT NT
18 2007/05/31 216.00 NT NT 15.00 <0.02 <0.02 <0.02 32.00 721.00 109.00 <0.02 NT <0.02 <0.02 <0.02 7.00 19.30
19 2007/06/11 NT NT NT 19.00 NT NT NT NT NT NT NT NT NT NT NT NT NT
20 2007/07/30 NT NT NT NT NT NT NT NT NT NT <0.02 NT NT NT NT 7.00 19.00
21 2007/08/20 NT NT NT 25.00 NT NT NT NT NT NT NT NT NT NT NT NT NT
22 2007/09/17 NT NT NT 20.00 NT NT NT NT NT NT NT <0.02 NT NT NT NT NT
23 2007/10/30 NT NT NT 7.00 NT NT NT NT NT NT NT NT NT NT NT NT NT
24 2007/11/30 212.00 108.00 350.00 11.00 <0.02 0.05 <0.02 15.00 322.00 104.00 <0.02 <0.02 <0.02 <0.02 0.03 4.00 3.00
25 2008/03/03 NT NT 625.00 NT NT NT NT NT NT NT NT 0.25 NT NT NT NT 15.00
26 2008/04/02 NT NT NT NT NT 0.05 0.05 10.50 NT 208.00 0.12 NT NT 0.10 NT NT NT
27 2008/05/13 165.00 150.00 NT NT NT NT NT NT NT NT NT NT NT NT NT 5.40 NT
28 2008/06/09 NT NT 457.00 NT . NT NT NT NT NT NT NT <0.02 NT NT NT NT 14.00
29 2008/07/23 NT NT NT 5.00 NT 0.03 0.02 10.60 NT 164.00 <0.02 NT NT 0.27 NT NT NT
30 2008/08/05 185.00 348.00 NT NT NT 0.05 NT NT NT NT NT NT NT NT NT 2.80 NT
31 2008/09/04 NT NT 395.00 NT NT 0.02 NT NT NT 213.00 NT NT NT NT NT NT 38.00
32 2008/10/14 NT NT NT 5.50 NT <0.02 <0.02 8.30 NT 36.00 <0.02 NT NT <0.02 NT NT NT
33 2008/11/17 304.00 152.00 NT NT NT NT NT NT NT NT NT NT NT NT NT 3.13 NT
34 2008/12/18 192.00 242.00 329.00 8.10 NT NT NT 8.80 NT 113.00 <0.02 <0.02 NT 0.32 NT 7.30 18.00
NT = Not Tested
Sample type Groundwater chemistry
Aquifer Aquifer 1
Borehole number BH23 BH24 BH25 BH26 BH27 BH28 BH29 BH30 BH31 BH32 BH33 BH34 BH36 BH38 BH39 BH108
Chemical substance
Sampling Hexavalent chromium concentration (mg/I)
Event Date
1 2004/11/03 68.90 0.08 0.03 0.07 0.02 NT 0.79 0.08 0.07 3.60 0.05 0.05 194.00 45.00 0.02 162.00
2 2005/05/05 107.00 0.02 0.02 0.02 0.05 36.00 0.56 0.04 0.04 1.34 0.01 0.01 239.00 29.00 0.02 173.00
3 2006/02103 NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT
4 2006/03/13 7.00 NT NT NT NT 28.00 0.28 NT NT 2.60 NT NT 74.00 88.00 NT 157.00
5 2006/04/05 NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT
6 2006/05/03 2.10 NT NT NT NT 14.00 0.06 NT NT 0.10 NT NT 116.00 60.00 NT 188.00
7 2006/06/13 NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT
8 2006/07/10 0.90 <0.02 <0.02 NT NT 7.00 <0.02 42.00 <0.02 0.02 <0.02 <0.02 128.00 <0.02 <0.02 179.00
9 2006/08/30 0.70 NT NT NT NT 17.00 0.09 NT NT 0.04 NT NT 125.00 17.00 NT 176.00
10 2006/09/27 NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT
11 2006/10/20 <0.02 NT NT NT NT 8.80 <0.02 <0.02 0.10 NT <0.02 <0.02 89.00 21.00 NT 186.00
12 2006/11/21 NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT
13 2006/12/07 <0.02 <0.02 <0.02 NT NT 1.00 <0.02 <0.02 <0.02 0.40 <0.02 <0.02 113.00 104.00 <0.02 188.00
14 2007/01/24 1.90 NT NT NT NT 0.80 0.20 <0.02 <0.02 0.08 NT <0.02 44.00 78.00 NT 169.00
15 2007/02106 NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT
16 2007/03/22 <0.02 NT NT NT NT 0.20 1.00 <0.02 <0.02 <0.02 <0.02 <0.02 42.00 83.00 NT 38.00
17 2007/04/16 NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT
18 2007/05/31 9.00 <0.02 <0.02 NT NT <0.02 <0.02 0.03 <0.02 0.10 <0.02 NT 49.00 52.00 <0.02 163.00
19 2007/06/11 NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT
20 2007/07/30 26.00 NT NT NT NT 0.60 <0.02 <0.02 0.50 <0.02 <0.02 <0.02 47.00 24.00 NT 167.00
21 2007/08/20 NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT
22 2007/09/17 NT NT NT NT NT 0.40 <0.02 NT NT NT 0.03 <0.02 44.00 21.00 NT 172.00
23 2007/10/30 NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT
24 2007/11/30 0.90 <0.02 2.00 0.50 <0.02 0.20 0.09 <0.02 <0.02 0.05 <0.02 <0.02 2.00 30.00 <0.02 102.00
25 2008/03/03 15.65 NT NT NT NT NT NT NT 0.17 0.34 0.16 0.17 NT NT NT 113.00
26 2008/04/02 NT <0.02 0.75 2.66 NT NT NT <0.02 NT NT NT NT NT NT NT NT
27 2008/05/13 NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT
28 2008/06/09 10.50 NT NT NT NT NT NT NT <0.02 0.12 <0.02 <0.02 NT NT NT 123.00
29 2008/07/23 NT <0.02 12.40 12.40 NT NT NT <0.02 NT NT NT NT NT NT <0.02 NT
30 2008/08/05 NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT
31 2008/09/04 16.40 NT NT <0.02 NT NT NT NT <0.02 <0.02 <0.02 <0.02 NT NT NT 151.00
32 2008/10/14 16.40 <0.02 8.80 2.90 NT NT NT <0.02 NT NT <0.02 NT NT NT <0.02 NT
33 2008/11/17 NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT
34 2008/12118 3.50 <0.02 26.70 6.60 NT NT NT <0.02 <0.02 0.17 <0.02 <0.02 NT NT <0.02 142.00
NT = Not Tested
Sample type
Groundwater chemistry
Aquifer Aquifer 1
Borehole number BH301 BH302 BH303 BH304 BH307 BH308 BH309 BH310 BH311 BH312 BH313 BH314 BH315 BH316 BH317 BH318
Chemical substance
Sampling Hexavalent chromium concentration (mg/I)
Event Date
1 2004/11/03 7.06 0.59 0.03 404.00 0.06 247.00 459.00 4592.00 3886.00 3515.00 3886.00 1406.00 422.00 257.00 237.00 0.08
2 2005/05/05 8.90 0.87 0.03 332.00 0.03 464.00 696.00 3838.00 7320.00 3819.00 3392.00 1428.00 446.00 267.00 178.00 0.03
3 2006/02/28 2.60 NT NT 173.00 NT 1057.00 443.00 NT 6580.00 2597.00 5887.00 520.00 NT 121.00 130.00 NT
4 2006/03/13 NT 0.17 NT 192.00 1.80 944.00 525.00 192.00 4058.00 2099.00 5596.00 525.00 595.00 78.00 122.00 NT
5 2006/04/21 NT NT NT 169.00 NT 1121.00 646.00 NT 2436.00 978.00 9750.00 920.00 NT 195.00 337.00 NT
6 2006/05/03 NT 3.30 NT 155.00 2.00 1218.00 729.00 377.00 2425.00 649.00 NT 1009.00 724.00 181.00 329.00 NT
7 2006/06/13 NT NT NT 151.00 NT 1297.00 1100.00 NT 2772.00 984.00 NT 1170.00 NT 220.00 320.00 NT
8 2006/07/10 NT <0.02 0.66 156.00 0.40 NT 1285.00 295.00 3405.00 NT NT 1220.00 654.00 206.00 299.00 <0.02
9 2006/08/30 NT <0.02 NT 151.00 1.30 809.00 80.00 NT 4185.00 1361.00 NT 920.00 NT 194.00 195.00 NT
10 2006/09/27 NT NT NT 161.00 NT 394.00 118.00 NT NT 195.00 8160.00 994.00 NT 186.00 274.00 NT
11 2006/10/20 NT <0.02 NT 167.00 5.40 221.00 136.00 97.00 7050.00 190.00 7180.00 715.00 679.00 177.00 NT NT
12 2006/11/21 NT NT NT 175.00 NT 250.00 95.00 NT 7350.00 283.00 NT 725.00 NT 252.00 232.00 NT
13 2006/12/07 NT <0.02 <0.02 183.00 2.30 103.00 74.00 21.00 2265.00 190.00 NT 523.00 714.00 179.00 125.00 <0.02
14 2007/01/24 NT NT <0.02 196.00 1.70 33.00 58.00 330.00 735.00 80.00 7080.00 590.00 670.00 57.00 15.00 NT
15 2007/02/19 5.00 NT NT 240.00 NT 100.00 260.00 NT 530.00 420.00 7000.00 680.00 NT 160.00 250.00 NT
16 2007/03/22 NT <0.02 <0.02 280.00 80.00 160.00 480.00 NT 820.00 NT NT 720.00 710.00 81.00 NT NT
17 2007/04/16 NT NT NT 370.00 NT 140.00 400.00 NT 670.00 590.00 7000.00 670.00 NT 99.00 NT NT
18 2007/05/31 NT <0.02 <0.02 252.00 1.70 123.00 567.00 NT 885.00 274.00 9260.00 730.00 690.00 79.00 NT <0.02
19 2007/06/11 NT NT NT 206.00 1.00 117.00 700.00 NT 1118.00 440.00 6830.00 820.00 NT 89.00 NT NT
20 2007/07/30 NT <0.02 <0.02 173.00 NT 152.00 497.00 NT 1758.00 315.00 5945.00 928.00 NT 93.00 NT NT
21 2007/08/20 4.00 NT NT 202.00 NT 204.00 391.00 NT 1413.00 486.00 6437.00 543.00 NT 102.00 NT NT
22 2007/09/17 NT NT NT 252.00 NT NT 303.00 NT 1372.00 319.00 NT 865.00 NT 96.00 NT NT
23 2007/10/30 NT NT NT 543.00 NT 326.00 320.00 NT 4630.00 430.00 NT 924.00 NT 39.00 NT NT
24 2007/11/30 2.91 0.30 <0.02 337.00 3.00 347.00 170.00 NT 4050.00 289.00 4150.00 910.00 448.00 48.00 NT 0.02
25 2008/03/03 NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT
26 2008/04/02 NT NT NT NT NT NT NT NT NT NT NT NT 760.00 NT NT NT
27 2008/05/13 2.87 0.19 <0.02 242.00 0.51 244.00 31.00 NT 3572.00 140.00 6518.00 1179.00 402.00 32.00 NT <0.02
28 2008/06/09 NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT
29 2008/07/23 NT NT NT NT NT NT NT NT NT NT NT NT 164.00 NT NT NT
30 2008/08/05 2.61 0.38 <0.02 254.00 0.21 218.00 65.00 NT 2499.00 334.00 5938.00 1282.00 498.00 34.00 NT <0.02
31 2008/09/04 NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT
32 2008/10/14 NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT
33 2008/11/17 2.64 0.28 0.10 143.00 1.22 162.00 143.00 NT 784.00 218.00 5907.00 1458.00 624.00 62.00 NT 0.02
~ 2008/12/18 NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT-
NT = Not Tested
Sample type Groundwater chemistry
Aquifer Aquifer 2
Borehole number BH201A BH202A BH203A BH204A BH205A BH206A BH207A BH208A BH211A BH212A BH214A BH215A BH217A BH218~BH221A BH223A BH224A BH225A
Chemical substance
Hexavalent chromium concentration (mg/I)
Sampling
Date
Event
1 2004/11/03 0.50 0.90 14981.00 23668.00 16249.00 95.00 5634.00 0.04 NT 66764.00 0.03 25939.00 3429.00 31.00 402.00 I NT NT NT
2 2005/05/05 NT NT 31623.00 24872.00 20964.00 51.00 4961.00 NT 0.02 64313.00 NT 18701.00 3731.00 50.00 427.00 0.03 11600.00 14763.00
3 2006/02/28 NT NT 42770.00 26320.00 23550.00 NT 3809.00 NT NT 15930.00 NT 17547.00 NT NT NT NT 23878.00 40252.00
4 2006/03/13 NT NT 41624.00 25424.00 22918.00 53.00 3580.00 NT NT 15756.00 NT NT 3497.00 42.00 700.00 NT 22386.00 39525.00
5 2006/04/21 NT NT 35500.00 23435.00 21337.00 NT 3847.00 NT NT 18888.00 NT NT NT NT NT NT 19900.00 38600.00
6 2006/05/03 NT NT 41500.00 22735.00 20287.00 83.00 3847.00 NT NT 18538.00 NT 15506.00 2690.00 79.00 530.00 NT 17200.00 29750.00
7 2006/06/13 NT NT 36600.00 22053.00 20158.00 NT 3704.00 NT NT 20158.00 NT 15130.00 NT NT NT NT 16100.00 32300.00
8 2006/07/10 <0.02 <0.02 40880.00 22429.00 20382.00 76.00 4183.00 NT <0.02 NT NT 14236.00 NT NT 414.00 NT 15800.00 36300.00
9 2006/08/30 NT NT 34700.00 20563.00 19860.00 63.00 4393.00 NT NT 26363.00 NT 13467.00 3175.00 49.00 NT NT 11650.00 18350.00
10 2006/09/11 NT NT 17750.00 18713.00 20462.00 19.00 4372.00 NT NT NT <0.02 14660.00 1360.00 NT NT NT 12400.00 16600.00
11 2006/10/20 NT NT 22750.00 18369.00 22785.00 80.00 3356.00 NT <0.02 25257.00 NT 15134.00 3220.00 108.00 NT NT 11250.00 10450.00
12 2006/11/06 NT NT 23360.00 NT NT NT 3647.00 NT NT NT NT 14910.00 NT NT NT NT 12345.00 11965.00
13 2006/12/07 <0.02 <0.02 NT 19490.00 21610.00 122.00 3170.00 <0.02 <0.02 21300.00 <0.02 12880.00 3680.00 51.00 290.00 <0.02 16910.00 14770.00
14 2007/01/24 NT NT 30000.00 18790.00 20210.00 130.00 4320.00 NT NT 21980.00 NT 13000.00 3500.00 80.00 510.00 NT 15000.00 15070.00
15 2007/02/19 NT NT 33000.00 16000.00 20000.00 NT 4000.00 NT NT 18000.00 NT 11000.00 NT NT NT NT 15000.00 22000.00
16 2007/03/22 NT NT 32000.00 14000.00 17000.00 130.00 3500.00 NT <0.02 18000.00 NT 12000.00 3500.00 44.00 300.00 NT 13000.00 18000.00
17 2007/04/16 NT NT 34000.00 16000.00 17000.00 NT 4000.00 NT NT 19000.00 NT 10760.00 NT NT NT NT 13000.00 13000.00
18 2007/05/31 <0.02 <0.02 40900.00 17110.00 18580.00 132.00 4000.00 <0.02 <0.02 21710.00 <0.02 10510.00 3100.00 33.00 448.00 <0.02 17120.00 13400.00
19 2007/06/11 NT NT 41300.00 15870.00 17800.00 NT 2804.00 NT NT 20740.00 NT 10520.00 NT NT NT NT 15780.00 11220.00
20 2007/07/30 NT NT 34250.00 15970.00 NT 157.00 3670.00 NT <0.02 20260.00 NT 10460.00 3410.00 49.00 502.00 NT 10470.00 10450.00
21 2007/08/20 NT NT 41080.00 15550.00 19130.00 NT 3605.00 NT NT 19950.00 NT 10170.00 NT NT NT NT 11420.00 10630.00
22 2007/09/17 NT NT NT 15640.00 18190.00 NT 4060.00 NT <0.02 18710.00 NT 9859.00 3040.00 31.00 498.00 NT 11330.00 10810.00
23 2007/10/03 NT NT 36480.00 14910.00 16540.00 31.00 3736.00 <0.02 NT 19600.00 NT NT NT NT NT NT 12030.00 11330.00
24 2007/11/30 <0.02 <0.02 34300.00 9808.00 21589.00 254.00 3676.00 <0.02 <0.02 21000.00 1.82 2932.00 3200.00 26.00 545.00 <0.02 10920.00 9069.00
25 2008/03/03 NT NT NT NT NT NT NT NT 0.16 NT NT NT 2952.00 19.00 NT 0.16 NT NT
26 2008/04/02 NT NT NT NT NT 212.00 NT <0.02 NT NT NT NT NT NT <0.02 NT NT NT
27 2008/05/13 0.10 0.59 232.00 12980.00 11604.00 NT 4655.00 NT NT 19054.00 <0.02 7876.00 NT NT NT NT 9755.00 7894.00
28 2008/06/09 NT NT NT NT NT NT NT NT <0.02 NT NT NT 2812.00 15.80 NT <0.02 NT NT
29 2008/07/23 NT NT NT NT NT 218.00 NT <0.02 NT NT NT NT NT NT <0.02 NT NT NT
30 2008/08/05 <0.02 <0.02 17823.00 11913.00 14207.00 NT 3792.00 NT NT 18909.00 <0.02 232.00 NT NT NT NT 8748.00 9876.00
31 2008/09/04 NT NT NT NT NT NT NT NT <0.02 NT NT NT 1634.00 38.00 NT <0.02 NT NT
32 2008/10/14 NT NT NT NT NT 344.00 NT <0.02 NT NT NT NT NT NT <0.02 NT NT NT
33 2008/11/17 0.10 0.27 28807.00 11485.00 12946.00 NT 1899.00 NT NT NT 0.10 251.00 NT NT NT NT 7293.00 9117.00
34 2008/12/18 <0.02 <0.02 NT 10970.00 2490.00 320.00 624.00 <0.02 <0.02 NT <0.02 243.00 4236.00 21.00 0.12 <0.02 NT NT
NT = Not Tested
Sample type Groundwater chemistry
Aquifer Aquifer 3
Borehole number BH201 BH202 BH203 BH205 BH206 BH208 BH209 BH210 BH211 BH213 BH214 BH216 BH217 BH218 BH221 BH222
Chemical substance
Sampling Hexavalent chromium concentration (mg/I)
Event Date
1 2004/11/03 0.10 0.06 0.03 371.00 0.11 0.02 0.03 0.03 0.05 0.03 0.02 0.01 0.02 0.04 0.02 0.02
2 2005/05/05 0.25 0.02 0.03 408.00 0.03 0.01 0.01 0.03 0.01 0.01 0.16 0.02 0.06 0.04 0.03 0.03
3 2006/02128 NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT
4 2006/03/13 NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT
5 2006/04/21 NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT
6 2006/05/03 NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT
7 2006/06/13 NT NT NT NT NT NT NT NT NT NT NT NT NT NT <0.02 NT
8 2006/07/10 <0.02 <0.02 1085.00 NT <0.02 <0.02 <0.02 <0.02 <0.02 46.00 <0.02 <0.02 <0.02 <0.02 NT <0.02
9 2006/08/30 NT NT 685.00 NT NT NT NT NT NT NT NT NT NT NT NT NT
10 2006/09/11 <0.02 <0.02 478.00 2990.00 NT NT NT NT NT 18.00 <0.02 <0.02 NT NT NT NT
11 2006/10/20 NT NT 463.00 NT NT NT NT NT NT NT NT NT NT NT NT NT
12 2006/11/06 NT NT 97.00 3200.00 NT NT NT NT NT NT NT NT NT NT NT NT
13 2006/12/07 <0.02 <0.02 50.00 42 <0.02 <0.02 <0.02 <0.02 <0.02 NT <0.02 NT NT NT <0.02 <0.02
14 2007/01/24 NT NT 218.00 79 NT NT NT NT <0.02 14.00 NT <0.02 NT NT NT NT
15 2007/02/19 NT NT NT 87 NT NT NT NT NT NT NT NT NT NT NT NT
16 2007/03/22 NT NT NT 1500.00 NT NT NT NT NT NT NT NT NT NT NT NT
17 2007/04/16 NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT
18 2007/05/31 <0.02 <0.02 NT NT <0.02 <0.02 <0.02 <0.02 <0.02 12.00 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02
19 2007/06/11 NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT
20 2007/07/30 NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT
21 2007/08/20 NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT
22 2007/09/17 NT NT NT NT NT NT NT NT NT NT NT NT 172.00 NT NT NT
23 2007/10/03 NT NT NT NT NT NT NT NT <0.02 NT NT NT NT NT NT NT
24 2007/11/30 <0.02 <0.02 NT NT <0.02 <0.02 <0.02 <0.02 <0.02 11.00 0.11 <0.02 <0.02 <0.02 <0.02 <0.02
25 2008/03/03 NT NT NT NT NT NT NT NT 0.16 NT NT <0.02 0.21 0.14 NT NT
26 2008/04/02 NT NT NT NT 0.10 <0.02 NT <0.02 NT NT NT NT NT NT <0.02 <0.02
27 2008/05/13 <0.02 <0.02 NT NT NT NT NT NT NT NT <0.02 NT NT NT NT NT
28 2008/06/09 NT NT NT NT NT NT NT NT <0.02 NT NT <0.02 <0.02 <0.02 NT NT
29 2008/07/23 NT NT NT NT <0.02 <0.02 <0.02 <0.02 NT NT NT NT NT NT <0.02 <0.02
30 2008/08/05 <0.02 <0.02 NT NT NT NT NT NT NT NT <0.02 NT NT NT NT NT
31 2008/09/04 NT NT NT NT NT NT NT NT <0.02 NT NT <0.02 <0.02 <0.02 NT NT
32 2008/10/14 NT NT NT NT 0.10 0.10 NT 0.10 NT NT NT NT NT NT <0.02 <0.02
33 2008/11/17 0.10 0.10 NT NT NT NT NT NT NT NT 0.10 NT NT NT NT NT
34 2008/12/18 <0.02 <0.02 NT NT <0.02 <0.02 <0.02 <0.02 <0.02 NT <0.02 <0.02 <0.02 0.17 0.12 <0.02
NT = Not Tested
Sample type Groundwaterchemistry
Aquifer Aquifer4 I Sandstone
Boreholenumber BH401 BH402 BH403 BH D1 BH D3 BH D5 BHC4 BHT BH OP BHCT BHAr BHCa
Chemicalsubstance
Sampling Hexavalentchromium concentratio(nmgII)
Event Date
1 2004/11/03 NT 0.04 0.03 <0.02 0.04 0.03 NT NT NT NT NT NT
2 2005/05/05 0.06 0.01 0.04 0.06 0.08 0.06 <0.02 0.01 NT <0.02 NT NT
3 2006/02/03 NT NT NT NT NT NT NT NT NT NT NT NT
4 2006/03/13 NT NT NT NT NT NT NT NT NT NT NT NT
5 2006/04/05 NT NT NT NT NT NT NT NT NT NT NT NT
6 2006/05/03 NT NT NT NT NT NT NT NT NT NT NT NT
7 2006/06/13 NT NT NT NT NT NT NT NT NT NT NT NT
8 2006/07/10 NT <0.02 <0.02 NT NT NT NT NT NT NT <0.02 NT
9 2006/08/30 NT NT NT NT NT NT NT NT NT NT NT NT
10 2006/09/27 NT NT NT NT NT NT NT NT <0.02 NT NT NT
11 2006/10/20 NT NT NT NT NT NT NT NT <0.02 NT NT NT
12 2006/11/21 NT NT NT NT NT NT NT NT NT NT NT NT
13 2006/12/07 NT <0.02 <0.02 NT NT NT NT NT <0.02 <0.02 <0.02 NT
14 2007/01/24 NT NT NT NT NT NT NT NT <0.02 NT NT NT
15 2007/02/06 NT NT NT NT NT NT NT NT NT NT NT NT
16 2007/03/22 NT NT NT NT NT NT NT NT <0.02 NT NT NT
17 2007/04/16 NT NT NT NT NT NT NT NT NT NT NT NT
18 2007/05/31 NT <0.02 0.20 NT NT NT NT NT NT NT NT NT
19 2007/06/11 NT NT NT NT NT NT NT NT NT NT <0.02 NT
20 2007/07/30 NT NT NT NT NT NT NT NT NT NT NT NT
21 2007/08/20 NT NT NT NT NT NT NT NT NT NT NT NT
22 2007/09/17 NT NT NT NT NT NT NT NT NT NT NT NT
23 2007/10/30 NT NT NT NT NT NT NT NT NT NT NT NT
24 2007/11/30 <0.02 <0.02 <0.02 NT NT NT NT NT NT NT NT NT
25 2008/03/03 NT NT NT NT NT NT NT NT NT NT NT NT
26 2008/04/02 NT NT NT NT NT NT NT NT NT NT <0.02 <0.02
27 2008/05/13 NT NT NT NT NT NT NT NT NT NT NT NT
28 2008/06/09 NT NT NT NT NT NT NT NT NT NT NT NT
29 2008/07/23 NT NT NT NT NT NT NT NT NT NT NT NT
30 2008/08/05 NT NT NT NT NT NT NT NT NT NT NT NT
31 2008/09/04 NT NT NT NT NT NT NT NT NT NT NT NT
32 2008/10/14 NT NT NT NT NT NT NT NT NT NT NT NT
33 2008/11/17 NT NT NT NT NT NT NT NT NT NT NT NT
34 2008/12/18 <0.02 <0.02 0.05 <0.02 <0.0_2_ <0.02 NT NT NT NT NT NT
NT = NotTested -
APPENDIX F
Analytical results of soil samples
TP1
TP2
TP5
TP?
TP8
TP11
TP13
TP14
TP15
TP16
TP1?
TP18
TP19
TP20
TP21
TP22
TP23
TP24
TP25
TP26
TP27
TP28
TP29
TP30
TP31
TP32
TP33
TP34
TP35
TP36
TP37
TP38
TP39
TP40
._.
·.·.1'."·· '," Sciiichenlistry 77
Depth .•p~ Total chromlum Chromium'(VI) Chr~m(il~,(IU) ,
.u, .2~ ...• ~Ji:i:ll:1gJ) .;, . (rmJUmL (r:i:lgL~gr (t.n9!kg)•• _··"A
Sand 0-0.3 8.32 432 4.34 427.66
Sand with reject 0.3 - 0.6 8.04 1950 3.11 1946.89
TP41 Sand to sandy gravel 0.6 - 0.9 8.19 187 9.05 177.95
Sand 0.9 -1.2 7.8 21764 15.8 21748.2
Sand 1.2 - 1.6 8.03 3281 108 3173
Sand with gravel 0.3 - 0.6 8.53 621 <0.02 620.98
TP42 Sand with gravel 0.6 - 0.9 8.4 1099
<0.02 1098.98
Sand with gravel 0.9 - 1.2 8.22 3855 0.1 3854.9
Sand with gravel 1.2 -1.6 8.64 4836 1.98 4834.02
Sand with gravel 0.3 - 0.6 8.47 2484 0.68 2483.32
TP43 Sand with gravel 0.6 - 0.9 8.58 4792 2.52
4789.48
, Sand with gravel 0.9 -1.2 8.27 12168 8.65 12159.35
Gravel 1.2 - 1.6 8.43 15289 3.99 15285.01
Sand with some boulders 0-0.3 8.51 9.56 0.16 9.4
Sand with some boulders 0.3 - 0.6 8.33 13.3 1.03 12.27
TP44 Sand with some boulders 0.6 - 0.9 7.73 59.4 0.32 59.08
Sand 0.9 - 1.2 5.39 3161 35.4 3125.6
Sand 1.2 - 2.2 7.36 10918 242 10676
Sand 0-0.3 6.99 111 2.74 108.26
Gravel 0.3 - 0.6 6.76 106 1.15 104.85
TP45 Sand 0.6 - 0.9 7.72 735 3.43 731.57
Sand 0.9 -1.2 7.27 12242 19.9 12222.1
Silly clay 1.2 - 2.0 6.38 19640 0.43 19639.57
Sand 0-0.3 8.72 168 <0.02 167.98
S01
Sand 0.3 - 0.6 8.05 121 <0.02 120.98
Sand 0-0.3 7.68 129 <0.02 128.98
S02
Sand 0.3 - 0.6 8.08 53 <0.02 52.98
Sand 0-0.3 6.91 122 <0.02 121.98
S03
Sand 0.3 - 0.6 8.05 167 <0.02 166.98
Gravel 0-0.3 7.48 81 <0.02 80.98
S04
Sand 0.3 - 0.6 7.61 825 <0.02 824.98
Sand 0-0.3 8.36 56 <0.02 55.98SOS
Sand 0.3 - 0.6 7.91 240 <0.02 239.98
Gravel 0-0.3 8 <0.02 7.98
S06 6.44
Sand 0.3 - 0.6 5.47 30 <0.02 29.98
Sand 0-0.3 7.81 611 0.02 610.98
S07
Sand 0.3 - 0.6 7.69 559 0.02 558.98
Sand 0-0.3 7.69 659 0.02 658.98S08
Sand 0.3 - 0.6 7.7 625 0.05 624.98
Sand 0-0.3 7.22 39 <0.02 38.98
S09
Gravel 0.3 - 0.6 6.86 508 <0.02 507.98
Sand 0-0.3 7.25 356 <0.02S10 355.98
Sand 0.3 - 0.6 7.77 1027 <0.02 1026.98
Sand
S11 0-0.3 7.36 21 <0.02 20.98
Sand 0.3 - 0.6 6.16 2 <0.02 1.98
Sand 0-0.3 7.41 44 <0.02 43.98
S12
Sand 0.3 - 0.6 6.71 30 <0.02 29.98
mbgl = meiers below ground level
APPENDIX G
Preliminary risk assessment (Tier 1 evaluation)
n.r 1 !:v.....uon
US8'A SOl c:roenIng guIcIeIIneo
Commerclalllnd __ rio
llepCIt ChromIum (VI) MIgrotlon to IIfOUn-
Tntpil No. (mbglr (~l
~_roupIor
IngeoIIonIIlenMI _
(~l pooff-ugullv. DAF-lO DAFa1(mgA<gl (mtA<gl
I_I
0-0.3 8.82 3400 510 38 2lP1
0.3~.8 1.22 3400 510 38 2
TP2 0.3-0.S 3M 3400 510 38 2
lP3 0.3-0.S 10.7 3400 510 38 2
TP4 0-0.3 325 3400 510 38 2
TP5 0.3-0.6 0.7 3400 510 38 2
0-0.3 1.2G 3400 510 38 2
TP7
0.3-0.6 0.91 3400 510 38 2
0-0.3 0.13 3400 510 38 2
TP8
0.3-0.S 1.75 3400 510 38 2
TPll 0.3-0.6 1.,46 3400 510 38 2
0-0.3 0.52
TP13 3400
510 38 2
0.3-0.8 0.36 3400 510 38 2
TP14 0-0.3 0.7 3400 510
38 2
0.3 -0.8 O.IT 3400 510 38 2
0-0.3 0.73
TP15 3400
510 38 2
0.3-0.8 0.23 3400 510 38 2
TP16 0.3-0.8 8.4 3400 510 38 2
TP17 0.3-0.8 8.39 3400 510 38 2
0-0.3 37S 3400 510 38 2
TP18
0.3-0.S 720 3400 510 38 2
0-0.3 4.22 3400 510 38 2TP19
0.3-0.S 3.31 3400 510 38 2
0-0.3 3.78 3400 510 38 2
lP20
0.3-0.6 7.53 3400 510 38 2
0-0.3 <0.02
TP21 3400
510 38 2
0.3-0.8 0.33 3400 510 38 2
lP22 0.3-0.8 2799 3400 510 38 2
0-0.3 1.78 3400 510 38 2
TP23
0.3-0.8 24 3400 510 38 2
0-0.3 1815 3400 510 38 2
TP24
0.3-0.8 1178 3400 510 38 2
0-0.3 454 3400 510 38 2
lP25
0.3-0.6 164 3400 510 38 2
0-0.3 3.07
TP26 3400 510
38 2
0.3-0.8 24.7 3400 510 38 2
0-0.3 421 3400 510 38 2
lP27
0.3-0.8 3188 3400 510 38 2
0- 0.3 787 3400 510 38 2
TP28
0.3-0.S 1340 3400 510 38 2
0-0.3 915 3400 510 38 2TP29
0.3-0.8 140 3400 510 38 2
0-0.3 17.7 3400 510 38 2
lP30
0.3-0.S 221 3400 510 38 2
0-0.3
lP31 23.4 3400 510
38 2
0.3-0.8 S2.2 3400 510 38 2
0-0.3 17.9 3400 510 38 2lP32
0.3-0.8 25.2 3400 510 38 2
0-0.3
TP34 536 3400
510 38 2
0.3-0.8 1827 3400 510 38 2
0-0.3 11.3
1P35 3400 510 38
2
0.3-0.8 27.1 3400 510 38 2
0- 0.3 50.1
TP36 3400 510
38 2
0.3-0.8 n.S 3400 510 38 2
lP37 0- 0.3 330 3400 510 38 2
0.3-0.6 623 3400 510 38 2
0-0.3 19.9
lP36 3400
510 38 2
0.3-0.8 58.4 3400 510 38 2
0-0.3 2.119
lP39 3400 510
38 2
0.3-0.6 2.03 3400 510 38 2
TP40 0.3-0.8 98.5 3400 510 38 2
TP41 0-0.3 4.34 3400 510 38 2
0.3-0.6 3.11 3400 510 38 2
TP42 0.3-0.S <0.02 3400 510 38 2
TP43 0.3-0.S 0.68 3400 510 38 2
0-0.3 0.18 3400 510 38 2
TP"
0.3 -0.8 1.03 3400 510 38 2
0- 0.3 2.74
TP45 3400 510
38 2
0.3-0.6 1.15 3400 510 38 2
mbgr = meteB below gl'OU'ld level
OAF = OikJlion AIIenuation FlICIor
TIer IEv_
US EPA Sol ."...Ina DUI_
Chromium (.1
Test pil No. (rngIk.1
In_on of fugutlvo DAFc20 DAF-1
(rngIk.1 (rnglkgl(mgllc.1 (mgllc.1
0-0.3 4347.18 No_"
0.3~.6 1271.78 1000000 UJw laxidtv. no guideine Noconcern
TP2 0.3 - 0.6 815.5<4 1000000 UJw lald:itv. no auideine Noconcern No_"
0.3-0.6 8160, 1000000 UJw told:itv. no auideine Noconcem
0-0.3 1<4&4.75 1000000 Low told:itv, no auideine Noconcern
lP5 0.3- 0.6 700. 1000000 Low lald:itv, no auldeine No concern
0-0.3 38A1 1000000 Low lald:itv, no auidein. No concern Noconcem
0.3-0.6 240.08 1000cx No c:oncem
0- 1.3 29.8 1000000 Low loldc:l!y,no guideine No c:onc:em No concern
0.3- 0.6 1006.25 Low lolddtv, no auideine ~ No c:oncem
lP11 3- J.6 206.5<4 1000000 Low loxldly, no .lOdeine No c:onc:em
0-0.3 315.48 1000000 UJw 10xldly' no auideine No eonc:em Noconcem
0.3- J.6 285.64 1000< Low 10xidtv, no auideine Na concem
0- 0.3 656.3 1000000 Low tolddtv, no auldein. No c:oncem No_"
0.3-0.8 263. 1000< Low 10lddtv, no ~ No conum ,.Noconeem
0- 0.3 53. 1000000 Low ,_, no aoidein. No concern
0.3-0.6 47.n 100C No concern
lP16 0.3-0.6 '331.l5 1000000 Low toxldly, no aoideine No c:oncem Noconcem
lP1' 0.3-0.6 10720.61 1000000 UJwtoldc:itv, noauidein. -NOconcem Noconcem
0-0.3 129524 100000c Low loldc:itv. no auldein. No concem
0.3 -0.6 186860 1000000 Low toldc:itv, no aoidein. . No concein Noconum
-0. 7253.78 1000000 Low loldc:itv. no au!deine No concem
0.3-0.6 93556.61 1000000 Low 10_, no guldein. No concern Noconcem
-0. 396.2;1 1000000 Low 1_, no auldein. No concern
0.3-0.6 626.47 1000000 Low t_, no aoideln. No concern Noconcem
0-0.3 5.16 ',000000
0.3-0.6 187.67 1000000 UJw toxldly, no auidein. No c:onc:em
TP22 0.3·0.6 15<40 UJwtoXicilv. no auideine ~ 'No concern
0-0.3 875.22 1000000 Low loldcilv, no auidein. No concern Noconcem
0.3-0.6 383076 1000000 Low loldcilv. no auidein. 'NOCOOCenl' Noconcern
0-0.3 308085 1000000 Low 10ldclty, no lI1Jidein. No conum
0.3-0.6 47652 1000000 No concern
0-0.3 161146 1000000 UJw loldcilv. no auldeine No concem Noconcem
0.3-0.6 360736 1000000 Low toldcilv. no auideln. No oancem No concern
0- o. 1189.8: 00000o UJw 10_. no auldeine No concem
0.3- 0.6 4165.3 1000000 UJw loldc:itv, no guldeine No c:oncem No concern
0-0. 115~ UJw to_. no auidein. No concem
0.3-0.6 39676 1000000 Low 10ldcitv, no guldeine No c:oncem No concern
0-0. 13393 0000 UJw loldcilv. no auldein. ~
0.3-0.6 162668 1000000 Low laldcilv, no guldeine No concern Noconcem
0-0.3 735:
0.3-0.8 20507 1000000 Low loldclty, no aoideine No concern Noconcem
0-0.3 42274.3 1000000 UJw 1_. no auidein. 'NOc:Oiiaim
0.3-0.6 13478 1000000 Low loldcilv, no guideine No concem
0-0.3 18788.6 1000000 Low toJÓ<Iv.no auideine No concern No concern
0.3-0.6 71950.8 1000000 Low 10JÓ<1v.no auidein. No concem Noconcom
0-0.3 35395. 1000000 UJw toldelv, no guidein. No concern Noconcom
O. -0.8 28591.8 lOOOOO1J UJw toxldv. no auideine No cancem Noconcem
0-0.3 65621 1000000 Low I_Iv, no auldein. No concern No concern
1.3-0.6 lllOOOOO Low 10JÓ< . no aUiileiin. ~
0-0.3 1412: 1DOOOOO Low taJÓ<Iv,no guldein. No concern No concern
0.3-0.6 4413.9 -iOOOOóO LDWloldcilv.noauldein. ~
0-0.3 62007.8 1000000 UJw loldcilv, no guideine No concern Noconcem
0.3-0.6 58507.2 1000000 Low 10ldcitv, no guldein. No concem-
0-11.3 4181 1000000 Low loldcilv. no auldeine No concom
0.3-0.6 9010 1000000 UJw loldcilv, no guidein. No c:oncem No conc:em
'-I '.3 6561. 1000000
0.3-0.8 152729.6 1000000 Low toldcilv, no guldeine No concern No concern
0-0.3 23 3.01 1000000 L- tolddtv. no auldein. ~
0.3-0.6 171 1.97 1000000 Low toldcitv, no guldein. No concern Noconcem
0.3-0.8 80401.5 1000000 Low toldcitv. no .uideine No concern No concern
-0. 427.88 1000000 Low 10_. no auldein. No concom Nocancem
0.3-0.6 1948.89 1000000 Low loldcitv, no gu!dein. No concern No c:onc:em
lP4: 0.3- ~.6 620.96 100Q00( LowtDidcliv, no .uldein. No concem Noconcem
0.3-0.8 2483.32 1000000 UJw loldclty, no guldein. No concern Noconcem
0-0.3 9A 1000000 Low taldcitv, no auideine -NCiCOIiCeii1
0.3-0.8 12.2 100000I UJw ,_, no auldein. No eoeeern No concern
0-0.3 106.28 1000000 Low toldcitv, no auidein. No c:oncem
104.85 1000< Low to_, no auldeine Nooonc:em Noconcem
mbgl" = mete~ below ground level
OAF = Dilution Attenuation Factor
n.r 1 Evaluation
US EPA Soil screening guldellIIM
0epIh Chromium (VI) ResIdentIII scenario Migration to groundwater
Test pit No. (mbglr (mg/kg) IngestlonlDenMl Inhlllllion of fugutive DAF=20 DAF=1
(mg/kg) p.rtlcul_ (mg/kg) (mWkg)
(n>g/I<g)
0-0.3 <0.02
S01 230 260 38 2
0.3 -0.6 <0.02 230 260 38 2
0-0.3
S02 <0.02 230 260 38 2
0.3-0.6 <0.02 230 260 38 2
0-0.3 <0.02
S03 230
260 38 2
0.3-0.6 <0.02 230 260 38 2
0-0.3
S04 <0.02 230 260 38
2
0.3-0.6 <0.02 230 260 38 2
0-0.3 <0.02 230 260 38 2
505
0.3 - 0.6 <0.02 230 260 38 2
0-0.3 <0.02 230 260 38 2
506
0.3-0.6 <0.02 230 260 38 2
0-0.3 0.02 230 260 38 2
507
0.3-0.6 0.02 230 260 38 2
0-0.3 0.02 230 260 38 2508
0.3-0.6 0.05 230 260 38 2
0-0.3 <0.02 230 260 38 2
509
0.3-0.6 <0.02 230 260 38 2
0-0.3 <0.02 230 260 38 2510
0.3-0.6 <0.02 230 260 38 2
0-0.3 <0.02 230 260 38 2
511
0.3-0.6 <0.02 230 260 38 2
0-0.3 <0.02 230 260 38 2
.-512 0.3-0.6 <0.02 230 260 38 2mbgl - meiers below ground level OAF - Dllullon Attenuation Factor
n.r 1 Evaluation
US EPA Soil screening guidelines US EPA Soil screening guidelines
0epIh Chromium (II) Resldentlll "".nul<> Migration to roundwaler
Test pit No. (mbglr (mg/kg) Ingestion/Dermal Inhlllllion of fugutlve DAF-20 DAF=1
(mg/kg) pmic:ul.es (mWkg) (mg/kg)
Irnlllkg)
0-0.3 167.98 120000 NS Noconcem No concern
501
0.3-0.6 120.98 120000 NS Noconcem Noconcem
0-0.3 128.98 120000 NS No concern No concern
502
0.3 -0.6 52.98 120000 NS No concern No concern
0-0.3 121.98 120000 NS No concern No concern
S03
0.3-0.6 166.98 120000 NS No concern No concern
0-0.3 80.98 120000 NS No concern No concern
S04
0.3-0.6 824.98 120000 NS Noconcem No concern
0-0.3 55.98 120000 NS Noconcem No concern
S05
0.3-0.6 239.98 120000 NS No concern No concern
0-0.3 7.98 120000 NS Noconcem No concem
506
0.3-0.6 29.98 120000 NS Noconcem No concern
0-0.3 610.98 120000 NS No concern Noconcem
507
0.3-0.6 558.98 120000 NS Noconcem No concern
0-0.3 658.98 120000 NS No concern No concern
508
0.3-0.6 624.98 120000 NS Noconcem No concern
0-0.3 38.98 120000 NS Noconcem No concern
509
0.3-0.6 507.98 120000 NS No concern No concern
0-0.3 355.98 120000 NS No concern No concern
Sla
0.3-0.6 1026.98 120000 NS Noconcem No concern
0-0.3 20.98 120000 NS No concern No concern
511
0.3-0.6 1.98 120000 NS Noconcem No concern
0-0.3 43.98 120000 NS Noconcem No concern
S12
0.3-0.6 29.98 120000 NS Noconcem No concern
mbgl.- meters below ground level OAF = Dilution Attenuation Factor
TIer 1Evaluation
Grou""-ter· RIsk based ScreenInfIlevela
Bonhole number Mulmum CrjVI)
("'11/1) Drlnldng_ lITIgation Uvatocl<
(~) (mall) (mall)
BHl 34200 0.05 0.10 1.00
BH2 503.00 0.05 0.10 1.00
BH3 862.00 0.05 0.10 1.00
BI« 269.00 0.05 0.10 1.00
BHS 0.01 0.05 0.10 1.00
BHl1 0.05 0.05 0.10 1.00
BH12 0.05 0.05 0.10 1.00
BH13 74.00 0.05 0.10 1.00
BH14 936.00 0.05 0.10 1.00
BH1S 21300 0.05 0.10 1.00
BH16 0.12 0.05 0.10 1.00
BH17 0.25 0.05 0.10 1.00
BH18 0.07 0.05 0.10 1.00
BH19 0.32 0.05 0.10 1.00
BH20 0.84 0.05 0.10 1.00
BH21 10.40 0.05 0.10 1.00
BH22 38.00 0.05 0.10 1.00
BH23 107.00 0.05 0.10 1.00
BH24 0.08 0.05 0.10 1.00
BH25 26.70 0.05 0.10 1.00
BH26 12.40 0.05 0.10 1.00
BH27 0.05 0.05 0.10 1.00
BH28 36.00 0.05 0.10 1.00
BH29 1.00 0.05 0.10 1.00
BH30 4200 0.05 0.10 1.00
BH31 O.SO 0.05 0.10 1.00
BH32 3.60 0.05 0.10 1.00
BH33 0.18 0.05 0.10 1.00
BH34 0.17 0.05 0.10 1.00
BHJe 239.00 0.05 0.10 1.00
BH38 104.00 0.05 0.10 1.00
BH39 0.02 0.05 0.10 1.00
BHl08 188.00 0.05 0.10 1.00
BH301 8.90 0.05 0.10 1.00
BH302 3.30 0.05 0.10 1.00
BH303 0.86 0.05 0.10 1.00
BH304 543.00 0.05 0.10 1.00
BH307 80.00 0.05 0.10 1.00
BH308 1297.00 0.05 0.10 1.00
BH309 1285.00 0.05 0.10 1.00
BH310 4592.00 0.05 0.10 1.00
BH311 7350.00 0.05 0.10 1.00
BH312 3819.00 0.05 0.10 1.00
BH313 97SO.00 0.05 0.10 1.00
BH314 1458.00 0.05 0.10 1.00
BH31S 724.00 0.05 0.10 1.00
BH316 267.00 0.05 0.10 1.00
BH317 337.00 0.05 0.10 1.00
BH318 0.08 0.05 0.10 1.00
BH201A O.SO 0.05 0.10 1.00
BH202A 0.90 0.05 0.10 1.00
BH203A 42770.00 0.05 0.10 1.00
BH204A 26320.00 0.05 0.10 1.00
BH205A 235SO.00 0.05 0.10 1.00
BH206A 344.00 0.05 0.10 1.00
BH207A 5634.00 0.05 0.10 1.00
BH206A 0.04 0.05 0.10 1.00
BH211A 0.18 0.05 0.10 1.00
BH212A 66764.00 0.05 0.10 1.00
BH214A 1.82 0.05 0.10 1.00
BH21SA 25939.00 0.05 0.10 1.00
BH217A 4236.00 0.05 0.10 1.00
BH218A 108.00 0.05 0.10 1.00
BH221A 700.00 0.05 0.10 1.00
BH223A 0.18 0.05 0.10 1.00
BH224A 23878.00 0.05 0.10 1.00
BH22SA 40252.00 0.05 0.10 1.00
_oIenu_ Tler 1 EvalulltlonGroun"_er- Risk basedScreening LewisMaxlmum Cr(\III
(mgIII DI1nklng_er ln1g11t1on Uvestodc
(maft) (mall) (maft)
BH201 0.25 0.05 0.10 1.00
BH202 0.10 0.05 0.10 1.00
BH203 1085.00 0.05 0.10 1.00
BH205 3200.00 0.05 0.10 1.00
BH206 0.11 0.05 0.10 1.00
BH208 0.10 0.05 0.10 1.00
BH209 0.03 0.05 0.10 1.00
BH210 0.10 0.05 0.10 1.00
BH211 0.16 0.05 0.10 1.00
BH213 46.00 0.05 0.10 1.00
BH214 0.16 0.05 0.10 1.00
BH216 0.02 0.05 0.10 1.00
BH217 172.00 0.05 0.10 1.00
BH218 0.17 0.05 0.10 1.00
BH221 0.12 0.05 0.10 1.00
BH222 0.03 0.05 0.10 1.00
BH401 0.06 0.05 0.10 1.00
BH402 0.04 0.05 0.10 1.00
BH403 0.20 0.05 0.10 1.00
BHD1 0.06 0.05 0.10 1.00
BHD3 0.08 0.05 0.10 1.00
BHD5 0.06 0.05 0.10 1.00
BHC4 <0.02 0.05 0.10 1.00
BHT 0.01 0.05 0.10 1.00
BHOP <0.02 0.05 0.10 1.00
BHCT <0.02 0.05 0.10 1.00
BHAr <0.02 0.05 0.10 1.00
BHCa <0.02 0.05 0.10 1.00
UV - UFS
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