A case study of On-site sanitation system on the quality of groundwater in hard rock terrain of Coimbatore city

摘要

The present case study has been undertaken to investigate the impact of On-site sanitation system on groundwater quality in the hard rock settings in Coimbatore city, India. Groundwater samples have been collected from the sites in Coimbatore city where the On-site sanitation systems are installed. The groundwater samples have been analysed for the major physico-chemical parameters and faecal coliform. Critical parameters considered in the analysis are namely nitrate, faecal coliforms and chloride. The presence of faecal coliform in bore wells indicates the contamination from On-site sanitation systems. A comparison of the present study with study carried out in the alluvial settings in India indicates that the contamination of groundwater in the hard rock areas is more as compared to the alluvial settings where On-site sanitation systems have been implemented. It is hypothesized that the secondary porosity in the hard rocks in the form of fractures leads to vulnerability of aquifer as compared to the porous sandy formations in the alluvial settings. It is desired that implementation of On-site sanitation systems in hard rock regions needs to be undertaken after detailed site specific hydrogeological studies.