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MEMORANDUM CH2MHILL <br /> Soil and Residue Management Plan, Stockton former <br /> Manufactured Gas Plant Site <br /> TO: Patricia Sullivan/PG&E <br /> COPIES: Jim Maniord/CH2M HILL <br /> FROM: Paula Bolio/CH2M HILL <br /> DATE: September 15, 1998 <br /> The purpose of this memorandum is to present the plan for managing soil and residue for <br /> the soil remedial alternative approved in the Remedial Action Plan (RAP) (CH2M HILL, <br /> March 1998) for the Stockton former Manufactured Gas Plant(MGP) site.Due to recent <br /> regulatory developments and further sampling,the management of soil and residue <br /> presented in the soil remedial alternative in the approved RAP needs to be modified as <br /> outlined below. <br /> The selected remedial alternative for soil as discussed in the approved RAP included <br /> excavation of soil in nine areas,including three source areas.Soil management was planned <br /> as follows: <br /> 1. Excavated soil that is below threshold levels will be used as backfill. <br /> 2. Soil and residues impacted with chemicals below hazardous waste levels will be <br /> disposed at a Class II landfill(such as nearby Forward Landfill). <br /> 3. Residues above California hazardous waste levels would be reused through onsite <br /> asphalt batching. In the RAP it was assumed that some residue from the bottom of <br /> Source Areas 1 and 2 and all of the residue from Source Area 3 would be treated using <br /> asphalt batching. <br /> Recent regulatory developments have changed the criteria for MGP wastes and soils <br /> containing constituents above RCRA criteria. These wastes and soil which were formerly <br /> exempt from RCRA regulation,and are now subject to management as a RCRA waste after <br /> August 24, 1998 (Land Ban Phase IV final rule,May 26, 1998, 63 Fed. Reg.64504) if they <br /> exhibit a RCRA hazardous characteristic. <br /> In addition,samples were collected from the most concentrated residues in Source Areas 1, <br /> 2, and 3 on April 8, 1998 for the purpose of further determining the type of disposal <br /> required for the residues.These samples were analyzed for total-concentrations of;PNAs, <br /> metals, BTEX,TPH-gasoline,and TPH-diesel, and for the TCLP concentration of benzene.In <br /> addition, fish bioassay tests were performed on these samples.The results of the residue <br /> sampling indicate: <br /> • Residue concentrations from Source Areas 1 and 2 do not exceed TCLP and TTLC levels <br /> and passed the fish bioassay test. <br /> • Residue from Source Area 3 exceeds the TCLP for benzene only and therefore can not be <br /> used for asphalt batching.In addition,it did not pass the fish bioassay test.Because this <br /> SFO/RESIDUE.DOC 1 110716.RA.ZZ <br />