DETERMINATION OF CONTAMINATION DISTANCE FOR BOREHOLES IN OKIGWE ZONE, IMO STATE NIGERIA
Groundwater contaminants in Okigwe zone in Imo state made up of six local government areas were investigated. Four (4) groundwater samples were collected from each local government area. This amounted to twentyfour groundwater samples. These samples were collected randomly from sites close to septic tanks and to avoid contamination from tanks, the samples were collected at the well head, before water enters into storage tanks. The samples were stored in a sterilized 250 ml bottles and then taken to the laboratory for analysis. The chemical parameters were determined using a HA-CH 44600-00 and using standard methods as contained in Chessbourgh (2014). These samples were refrigerated and analyzed within 24 h. All plastics and glass wares utilized were pre-washed with detergent water solution, rinsed with tap water and soaked for 48 h in 50% HNO3 then rinsed thoroughly with distilled- deionized water. These results were used to ascertain the levels of groundwater contamination in Okigwe zone. An equation was generated from the chemical parameters using SPSS and E-view softwares to estimate the minimum allowable distance for locating borehole from sources of contamination in Okigwe zone in Imo state Nigeria. The minimum allowable distance calculated for groundwater from sources of contamination (septic tanks) is 15.81meters.