Assessing the Suitability of sites for Reclaimed Water Recharge using Hydrogeophysical and Hydrochemical Analysis

An electrical resistivity survey was carried out in the premises of Chennai Metrowater Sewage treatment plants and Anna University to assess the suitability of underlying aquifer for reclaimed water recharge and also to understand groundwater conditions. The geo-electrical methods used in the survey are Vertical Electrical Sounding (VES) using the Schlumberger Configuration. The instrument used is ABEM Terrameter SAS 1000. The VES data from 5 locations were interpreted using IX1Dv2 software. The resistivity varies from 3.96 Ωm to 2796 Ωm while the thickness varies from 0.58 m to 43.05 m. The EC value for VES 1 and VES 3 are 26400 µS/cm and 1551 µS/cm, the TDS value for VES 1 and VES 3 are 16,896 mg/L and 993 mg/L respectively. From this investigation, the thickness of the first layer obtained by VES method along with clay and sand ratio is the deciding factor to assess the suitability of reclaimed water recharge. The study reveals that the Clay and Sand % should be between 30 - 40 and 60 - 70 respectively for reclaimed water recharge. Koyambedu and Anna University STP and surrounding area are found suitable for reclaimed water recharge using Soil Aquifer Treatment.