Effect of Seepage from Unlined Municipal Waste Stabilization Lagoons on Chemical Quality of Groundwater in Shallow Aquifers

摘要

Groundwater quality changes were investigated around six unlined municipal waste stabilization lagoons in North Dakota. The lagoons chosen were constructed in permeable sediments directly over shallow, unconfined aquifers. Groundwater contamination at all sites is characterized by a plume of water with low redox potential and high dissolved-solids content extending downgradient from the impoundments. At McVille, the site with the most severe contamination, untreated wastewater is maintained in one cell throughout the year except when short intermittent discharges of wastewater are made into an adjacent cell. Seepage water quality is apparently better when adequate holding time is maintained in a cell with a basal sludge layer. Water downgradient from the intermittently-used cell has a very high ammonium concentration, which is subsequently decreased by adsorption. Evidence suggests that coliform organisms can move several hundred feet away from the lagoons in groundwater under favorable conditions.