Abstract

In semi-arid areas water supply systems are mainly dependent on pumping groundwater. However, urbanization, industrial development and agricultural activities usually lead to deterioration of the groundwater quality. Therefore, in many cases water supply wells are abandoned when the quality of the water pumped from these wells is lower than required by the water consumers. Primarily, wells used for supplying drinking water are abandoned if not all restrictive water quality parameters' values are met. Therefore, the decline of groundwater quality is associated with decreasing the available quantities of water resources. Further, abandoning water supply wells leads to risks of contaminant migrating into other wells located in parts of the aquifer, which are currently free of contaminants. Documented case histories indicate the worst approach is well abandoning. As this approach does not control processes causing the aquifer contamination and may lead to expensive solutions of supplying drinking water to the population. As an example, presently in Israel water supplying wells are abandoned, and large scale plants of sea water desalination are constructed to provide the missing supply of groundwater, whereas treating the polluted groundwater often costs significantly less than desalting sea water. In some case histories reviewed by our study, we have found that continuing pumping water from the abandoned wells could serve as a proper means avoiding spreading of the contaminant in the aquifer. Therefore, our study extends the simplified method of our previous studies (Rubin et al. 2008; 2009) for preliminary evaluating the needs for hydraulic barriers in cases of groundwater contamination. Special attention is given to cases of groundwater contamination by non-aqueous-phase-liquids (NAPLs) that are entrapped in the aquifer. The method provides information about the hydraulic barrier controlling the contaminant plume spreading and also about the aquifer remediation as a by-product of the operating hydraulic barrier.