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TV GM FY [C. i 13 pumping well will be installed on site. An aquifer test will be performed using the pumping well to provide information for pump selec.ion and for determining the capture zone of the well. Based on the results of the aquifer test, an additional pumping well may be required to provide adequate hydraulic control over the entire groundwater plume. The goal of the remediation system is to remove and treat both'(i)the petroleum hydrocarbons adsorbed to the soil, in the vapor phase in the unsaturated zone, and floating as a separate-phase on the water table,and(e)to extract and treat petroleum hydrocarbon-impacted groundwater while nxening hydraulic control on the plume. The un.%aturated zone hydrocarbons are a continuing source c solved hydrocarbons to groundwater and must be removed if groundwater treatment is to be effective. 3.2 Site Safety Plan Prior to commencing the remediation phase of the project, the existing Site Safety Plan will be revised to reflect the additional activities to be conducted on site. The revisions will be prepared in accordance with occupational Safety and Health Administration(OSHA)guidelines set forth in'Hazardous Waste Operations and Emergency Response' (29 CFE° 1910.120). The document will be reviewed and personnel and subcontractors performing work on site. A copy signed by all Groundwater Technology will be present on-site at all times and kept in an easily accessed location. _ 3.3 Soil Vapor Extraction and Emission Control 3.3.1 Soil Vapor Extraction Pilot Test Methods Groundwater Technology conducted a soil vapor extraction pilot test from May S to May 14,1990. Prior to conducting the test,permission was obtained from the San Joaquin Air Pollution Control District to temporarily discharge the soil vapors through a ten foot high effluent stack. Existing monitoring wells were used as vapor extraction wells. These wells are screened through the unsaturated zone above the first clay layer from 10 feet to 25 feet BGS. The test was conducted to determine the radius of influence of each extraction well,and the concentration of hydrocarbons in the soil vapor extracted from each well. Vapors were extracted from the extraction well by a 1.5 horsepower regenerative blower. During the test, the flow rate was monitored with a Kurz model 440 air velocity meter, and was varied between 130 and 37 cubic feet per minute(cfm). To determine the radius of influence,the vacuum pressure was measured in monitoring wells at variable distances from the extraction well using a magnehelic gauge. Samples of soil vapor were collected in Tediar bags and shipped under a chain-of-custody to Groundwater Technology Environmental Laboratories, Inc. (GTEL) for analysis. The samples were T analyzed according to U.S.Environmental Protection Agency(EPA)Methods 8015 and 8020 fir benzene, T D, CRntlNIAVNrE R Trcit\t?LOGY,INC.