Impact of sanitary landfill on groundwater quality

This paper presents the results of monitoring the shallow groundwater quality around two municipal landfill sites in the Eastern Province of Saudi Arabia. Boreholes were installed at Dhahran and Juaymah sites upstream and downstream of the landfill. Twenty water samples were collected from each borehole and analyzed for various parameters mainly for BOD, COD, TOC, NH₃-N, TKN, sulphate, chloride, hardness and metals. The result of the analysis of water samples from Dhahran boreholes shows an increase in the concentration of pollutants in downstream groundwater over that observed in upstream boreholes. The average concentration of BOD₅, COD and TOC in the samples obtained from the downstream borehole was found to be 6.5, 23.5, and 34.3 mg L^-1, respectively. On the other hand, the mean concentration of the same parameters in upstream monitoring wells was found to be less than 2.4, 11.5, and 10.0 mg L^-1, respectively. The ammonia-N and organic-N in the downstream wells were 0.37 and 0.29 mg L^-1, respectively, whereas, in upstream wells they were 0.11 and 0.15 mg L^-1, respectively. At Juaymah, the average concentration of BOD and TOC in groundwater samples obtained from upstream boreholes were less than 3.0 and 7.2 mg L^-1, respectively, while the concentration of the same parameters in downstream well samples were above 5.0 and 35.0 mg L^-1, respectively. A similar trend of increment of ammonia-N, organic-N, phosphate, sulfate and metals in downstream samples was observed. Since the water from these shallow aquifers at both places is not being used for human consumptions or for any other commercial purpose, therefore, the minor increase in pollutants concentration at downstream level is not of a great concern.