Evaluation of Urban Groundwater Contamination from Sewage Network in Kuwait City

Abstract

To investigate the possible contamination of groundwater by wastewater leaked from the underground sewage network, water samples from 29 monitoring wells, drilled at strategic locations across Kuwait City and the adjacent residential areas, were analyzed for their inorganic and organic constituents including isotopic composition (oxygen-18 and deuterium) that can be used as tracers for source identification. As a non-conventional method, statistical processing in the form of hierarchical cluster and discriminant function analyses of the inorganic and organic data was used to group the wells according to the degree of possible contamination of groundwater. It was concluded from this analysis that more than half of the wells (17) showed little evidence of such contamination. Sample from only one of the wells suggested high degree of contamination (concentrations of total coliform bacteria (TCB) and fecal coliform bacteria (FCB) >2,000 MPN/100 ml and boron (B) concentration >11 mg/l) whereas another well appeared significantly contaminated (TCB > 2,000 MPN/100 ml; FCB > 900 MPN/100 ml; B > 4 mg/l). Three of the wells were possibly contaminated (1,000 < TCB < 2,000 MPN/100 ml; 15 < FCB < 500 MPN/100 ml; 3 < B < 11.5 mg/l), and the rest of the seven wells were classified as possibly not contaminated (TCB > 2,400 MPN/100 ml; FCB < 40 MPN/100 ml; B < 5 mg/l). The overall conclusion was that the leakage from sewage network was affecting groundwater in localized areas only. Isotope data, available for water samples from eight of the monitoring wells, tended to support the aforesaid conclusions. However, because of the use of bailing as the sampling method and lack of actual leakage surveillance, further studies need to be carried out to strengthen the reliability of these findings.