CHENNAI: Concerned over the finding that the groundwater in Namakkal has been highly polluted due to sewage seeping from septic tanks, a study is on at Nammakal and Erumaipatti towns to arrive at a scientific solution to resolve this issue.
The ‘Groundwater Sanitation Nexus Research’ is a collaborative effort by the Municipal Administration and Water Supply department of the State government, IIT-Madras and two private organisations to develop an improvised septic tank design for these towns.
Namakkal in western Tamil Nadu is one of the fastest-growing municipalities in terms of ground cover (40 % in the last five years). In the absence of an underground sewerage network, individual households have set up quick pit latrines, septic tanks or sewage dumping sites at their backyards for collection of waste from their toilets.
According to government norms, these tanks should desludged (emptied) using vacuum trucks once in three years. “But during our inspection, we found out most houses haven’t desludged in over 20 years,” said S L Sathyanethan of LEAF Society, an organisation that is working with the government on this. Over the years, he added, water mixed with faeces has seeped through the base soil, contaminating the groundwater table.
Motorised pumps or hand pipes (in high groundwater table areas) located close to these pits directly pump out contaminated water, which the people consume without any effective treatment, said M Sundar from Bengaluru-based Arghyam Foundation which is funding the project alongside the State government. Drinking untreated water with bacterial (faecal coliforms) and chemical contamination will have adverse effect on the health of the people, he added.
However, underground drainage projects involve high capital, operation and maintenance cost, and more importantly, consumes water twice the amount when compared to conventional systems (60 litre per capita). This project is trying to address the issue with an technical and engineering solution.
In the first phase, a survey is being conducted by IIT-M, LEAF and Arghyam to identify the level of groundwater contamination. The team’s recent meeting with the Tamil Nadu Water Supply And Drainage (TWAD) Board officials revealed that there were only three observation wells in the district, and data were insufficient. So LEAF has been assigned the task of collecting groundwater samples from 5,000 households in and around Kosavampatti Lake. In the meanwhile, IITM will monitor water quality from 40 wells located in Namakkal and Erumaipatti towns, and rest from wells located away from the two towns in the proximity of Cauvery river where the groundwater level will be high.
Water will be collected once in three months for one month duration and will be analysed for bacterial and chemical parameters, which will help establish the connection between septic tanks and pit latrines and their impact on groundwater quality.
During the second phase, improvised septic tanks designed by IIT-M will be built and pilot scale studies conducted to analyse performance and improvise on it, sources added. While the Tamil Nadu government has sanctioned Rs 40 lakh as a part of the ‘Vision 2023’ program, Arghyam foundation will spend close to Rs 30 lakh on the project.