Environmental impact of point pollution sources

English: Due to the importance of groundwater as an alternative for supplementing existing sources of this precious fluid, any study that may help in understanding the complexity of the groundwater environment is an asset. Therefore this dissertation was written with the sincerest hope that the people and organisations involved with groundwater will gain a better understanding of it. The need to protect our groundwater sources has become very important and therefore a different, more practical approach to delineate borehole protection zones was considered based on the existing standards set by Germany and other European nations. As part of the study, emphasis was placed on the effect of the unsaturated (vadose) zone on the migration of pollutants before it reaches the groundwater environment. Field tests on the saturated as well as unsaturated zones were conducted with a conservative tracer (Fluorecein) as well as microbial tracers (bacteriophages), to assist in the delineation process. Thereafter it was decided to propose that three protection zones should be assigned depending on i) the size of the population and ii) the vulnerability and importance of the aquifer. The effect of a pollutant on human health and the possibility of fatalities were the criteria for deciding which protection zone is applicable under given circumstances. Protection zone I involves fencing off the immediate area around the borehole (a radius of 5 m is proposed) as well as the necessity of a well-constructed sanitary seal. Where a borehole supplies water to less than 20 people, a sanitary seal will be sufficient. To determine the extent of protection zone II, the idea was to protect the drinking water from microbial (bacteria and viruses) and nitrate pollution. Emphasis was placed on these two parameters because of their association with pitlatrines and septic tanks. Methods to estimate the fracture extent are proposed and, depending on the estimation of the nitrate and bacterial travel times and loads, a guideline to use i) half the fracture extent, ii) the whole extent of the fracture or iii) double the fracture extent, is proposed. Only if there is the possibility of a hazardous substance that may pollute the groundwater, it is proposed that protection zone III be assigned. The use of the word "hazardous" could make the decision more complex and therefore the issue of risk assessment and management is also addressed very generally in this dissertation. The proposed extent for protection zone III is the whole catchment area of the borehole. A programme called Borehole Protection Zone (BPZONE) was developed by making use of Microsoft Excel to assist the person(s) responsible in the decision making processes of delineating borehole protection zones. Information gathered during the field tests conducted at the Campus Test Site of the University of the Free State as well as the Meadhurst Test Site outside Bloemfontein, yielded very positive results, in terms of delineating protection zones.