An Assessment of Groundwater Quality in the Land Area around the University of Sri Jayewardenepura

Abstract

The groundwater quality in the land area around the premises of University of Sri Jayewardenepura which belongs to Boralesgamuwa, Gangodawilla and, Nawinna in Colombo district was investigated. The land area was divided in to 4 clusters depending on the population and water samples from 96 randomly selected domestic wells were obtained during the wet season (October-March 2008/2009). Samples were analyzed for 14 water quality parameters, namely pH, temperature, conductivity, turbidity,NO2-, NO3-, total hardness, total iron, TS, DO, COD, BOD, heavy metals (Zn, Mn, Cr and Pb), and total coliform and E.coli using the standard methods specified by SLSI.

Results showed that the pH (3.2-6.9) of about 95.8% of the samples were not within the SLS standards while with respect to conductivity (61.2-719 ìS cm-1), total hardness (8.3-233.8 ppm), and NO3- (0.09- 4.0 ppm), samples were within the permissible level. Very few samples showed high turbidity values (0.1-133 NTU), total iron (0-3.12 ppm), and TS (20-1643 ppm). NO2- concentration (0-0.34 ppm) was found to be rather high in the area and also when considering the DO (1.8-8.69 mg O2 dm-3), COD (3.81-60.85 ppm), and BOD (0.41-19.27 mg O2 dm-3) values some of samples were not within the permissible level. Groundwater contamination by Zn (0-0.798 ppm) and Mn (0.016-0.291 ppm) was significant in the area around the university, but all the values were below the permissible level. Cr and Pb were found to be absent in all samples tested.

Most of the samples tested showed high MPN numbers (3-1100) exceeding the levels given in SLS standards, the samples obtained from the area around Nawinna dumping site was contaminated with E.coli.