Leachate from Land Disposed Residential Construction Waste

Abstract

Solid waste from construction and demolition (C&D) activities is often disposed in unlined landfills. Leachate from unlined landfills poses a potential risk to groundwater quality. An understanding of the types of chemical constituents likely to be encountered in C&D waste landfill leachate and the concentrations at which they occur help assess this risk. An experiment was performed to characterize leachate from land-disposed residential construction waste. Four 54 m2 (580 ft2) test cells were excavated, lined, and filled with waste. Leachate samples were collected and analyzed for a number of water quality parameters over a 6 month period. No volatile or semivolatile organic compounds were detected at elevated constituent levels in the leachate. Inorganic ions were found to account for the bulk of the pollutant mass leached. Calcium and sulfate were the predominant ions in the leachate, resulting from the dissolution of gypsum drywall. The concentrations of several leachate constituents were found to exceed water quality standards. These constituents included aluminum, arsenic, copper, manganese, iron, sulfate, and total dissolved solids. Arsenic was the only primary water quality standard exceeded. The arsenic was concluded to result from chromated copper arsenate (CCA)-treated wood. The potential risk of impacting groundwater was examined by comparing the measured constituent concentrations with the water quality standards to assess the amount of dilution and attenuation needed in the groundwater so that a water quality standard would not be exceeded. The water quality standard exceeded by the greatest magnitude was manganese, followed by iron.