In an effort to characterize the waste streams at a typical utility fly ash landfill, a large outdoor test cell of compacted fly ash was constructed in 1984 at the Pennsylvania Power & Light Company's Montour Steam Electric Station. The test cell is a scaled-down version of the active dry fly ash disposal facility at the plant and includes a liner, a leachate collection system, and surface water runoff perimeter drains. It is 100 feet by 100 feet at the base and 10 feet high with 2:1 vertical:horizontal side slopes, giving a top area of 60 feet by 60 feet. The test cell is instrumented to measure precipitation, infiltration, surface runoff, unsaturated flow, evapotranspiration and leachate drainage. This paper presents a preliminary evaluation of the chemical composition of leachate generated from the test cell during the first year of leachate production. Leachate samples are periodically collected from a concrete sump to which the leachate collection system drains. Leachate first appeared in the sump in October 1985, approximately one year after the test cell was constructed. Samples are analyzed for pH, specific conductance, 22 metals, and 10 ions. The concentrations of parameters present in the test cell leachate are compared to drinking water standards and to standard laboratory extraction results. Parameters not detected in the leachate are also identified. The preliminary findings of the leachate monitoring effort are providing valuable information on the initial quality of leachate generated under field conditions. This data will be useful in the design of leachate control systems, wastewater treatment facilities and ground water monitoring programs for future ash disposal operations.

No abstract

The Pennsylvania Power & Light Company, in cooperation with the Electric Power Research Institute, is studying leachate generation at a large outdoor test cell of compacted coal combustion fly ash constructed at the Montour Steam Electric Station in north-central Pennsylvania. The test cell design is identical to that of the plant's active dry fly ash disposal facility. Leachate initially generated at the test cell contained concentrations of chromium and selenium approximately ten times above EPA's assigned Maximum Contaminant Levels (MCL's) for drinking water. Concentrations of these two parameters have since decreased approximately five-fold. Similar reductions have occurred in the concentrations of several of the other trace metals measured in the leachate. The dominant reaction mechanisms controlling leachate composition were examined in an attempt to explain these and other observations. Deterministic chemical modeling was performed to aid in the interpretation of the data. The dynamics of leachate generation were also examined through an evaluation of the infiltration and redistribution of moisture.

No abstract

No abstract