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Geosyntec Consultants <br /> 5, LEACHATE FROM LAND DISPOSED RESIDENTIAL <br /> CONSTRUCTION WASTE <br /> Presently, the SWDD disposes C&D debris in unlined landfills . The leachate created <br /> from the interaction of C&D waste with rainfall or groundwater may contain trace <br /> amounts of hazardous chemicals. Sources of such chemicals include solvents and <br /> adhesives, as well as the primary construction material themselves. While the chemicals <br /> leaching from materials such as wood, drywall and concrete are not typically toxic, they <br /> can contribute to an overall degradation of groundwater quality. Simulated leachate <br /> from C&D debris containing drywalls was found to exceed the secondary maximum <br /> contaminant levels for drinking water for Total Dissolved Solids (TDS) and sulfate (3 ). <br /> Also, sulfides were formed from the conversion of sulfate by sulfate-reducing bacteria <br /> under the unsaturated and anaerobic conditions. <br /> In another study of the quality of C&D debris leachate, which included both laboratory <br /> and field tests, leachate generated from C&D debris was found to be turbid and black in <br /> color and contained a strong hydrogen sulfide odor (4). The source of sulfate was <br /> believed to be the dissolution of gypsum drywall (CaSO4 2H2O). Also, aluminum, iron, <br /> and manganese were detected in all of the leachate samples. Arsenic, chromium, <br /> copper, and lead were also routinely detected. The most likely source of arsenic , <br /> chromium, and copper was chromated copper arsenate (CCA)-treated wood. CCA- <br /> treated wood was a common construction component in Florida. Trace organic <br /> compounds may be found in paint thinners, stains, motor oils, plastics and paints, which <br /> are not uncommon, but occasionally observed in the construction waste stream. <br /> 6. COST COMPARISON OF C&D DEBRIS DISPOSAL IN AN UNLINED <br /> LANDFILL VS. CO-DISPOSAL IN A CLASS I LANDFILL <br /> The methodology of the cost comparison study of the two C&D debris landfill disposal <br /> alternatives includes the following steps: <br /> I . Estimate the landfill capacity of Cell 2 for commingled waste <br /> 2 . Estimate the cost of constructing Cell 2 as a Class I landfill <br /> 3 . Estimate the Closure cost of Cell 2 as a Class I landfill <br /> 4. Estimate the operation and maintenance cost of Cell 2 as a Class I <br /> landfill <br /> 5 . Compute a $/ton cost estimate for construction and operation and <br /> maintenance of Cell 2 as a Class I landfill <br /> JR70184 7 7/13/2007 <br />