Geohydrology and Ground-Water Geochemistry at a Sub-Arctic Landfill, Fairbanks, Alaska

摘要

The Fairbanks-North Star Borough landfill is located on silt, sand, and gravel deposits of the Tanana River flood plain, about 3 miles south of the city of Fairbanks water-supply wells. The landfill has been in operation for about 25 years in this sub-arctic region of discontinuous permafrost. The cold climate limits biological activity within the landfill with corresponding low gas and leachate production. Chloride concentrations, specific conductance, water temperatures, and earth conductivity measurements indicate a small plume of leachate flowing to the northwest from the landfill. The leachate remains near the water table as it flows northwestward toward a drainage ditch. Results of computer modeling of this local hydrologic system indicate that some of the leachate may be discharging to the ditch. Chemical data show that higher-than-background concentrations of several ions are present in the plume. However, the concentrations appear to be reduced to background levels within a short distance along the path of ground-water flow from the landfill, and thus the leachate is not expected to affect the water-supply wells.