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Treatment of Nonvolatile Petroleum Hydrocarbon Contaminated Soil The "Operation and Maintenance Manual, Soil Treatment System, Forward, Inc., Landfill Unit WMU G, Stockton, California" (Harding Lawson Associates, April 1991) describes the treatment system for nonvolatile petroleum hydrocarbon contaminated soils. The specifications and reporting requirements of the treatment system are specified in the WDRs, Order No. 97-141 and in the October 31, 1990, letter from SJCPHS to Forward. The contaminated soil treatment system consists of an area where appropriate fertilizers are added to the contaminated soil and the soil is mechanically aerated to accelerate biodegradation of hydrocarbons (bioremediation process). The objective of the treatment process is to biodegrade the hydrocarbons to levels appropriate for landfilling. After the contaminated soils have been adequately treated, the soil can be used for daily cover, intermediate cover, or foundation layer for the closure cap. If necessary, the treated soils can be disposed in a Class II or Class III WMU. Although there are currently no Land Treatment Units (LTUs) at the site, LTUs have been constructed in the past and may be utilized in the future. LTUs for contaminated soil are permitted within WMU G-North or G-South. The units are approximately 40 feet wide by 500 feet long. The number of operating LTUs at any given time will vary according to the market need for the soil treatment process. Previously constructed LTUs have consisted of a 40-mil polyvinyl chloride (PVC) liner covered with a 6-inch-minimum thickness layer of sand and gravel, an 18-inch minimum thickness layer of compacted clay, and a 6-inch-minimum thickness layer of a sand and gravel buffer zone. A layer of contaminated soil approximately 18 inches thick is placed within each LTU for treatment. Berms contain stormwater within the LTUs, and a drainage system removes storm- water that accumulates. The surfaces of the LTUs will be sloped so that excess rainwater drains to a storage tank. Water stored in the tank will be used for soil moisture control during the treatment process or pumped to the leachate evaporation pond. A monitoring system has been designed to test the soils to ensure the efficiency of hydrocarbon biodegradation. Soils in the LTUs will be sampled regularly to evaluate and manage the key treatment parameters such as soil moisture, soil pH, Forward Landfill JTD 6-15 J:\Allied\Forward\JTD Amendment\Final JTD Amendment\JTD Rev Sec 6 080105.doc:5/22/02 Rev.1:7/2002:Rev.2:4/2003;Rev 3:6/2003 Amendment No.1:8/1/2005