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' GEOMATRIX <br /> ' constrained to within 50 feet of the right-of-way but may be present as far as 180 feet laterally <br /> from Byron Road. <br /> ' 2.2 SITE HYDROGEOLOGY AND GROUNDWATER QUALITY <br /> The subsurface soil within the project area is predominantly silt and clay with isolated sandy <br /> ' lenses to a depth of at least 20 feet. The recent depth to the water table is approximately 5 to 10 <br /> feet bgs and groundwater generally flows to the north-northeast in the project vicinity. Based <br /> ' on the results of the groundwater investigations performed at the subject sites,the Regional <br /> Water Quality Control Board(RWQCB), the Department of Toxic Substance Control (DTSC), <br /> ' and/or the San Joaquin County Environmental Health Department (EHD) have determined,that <br /> the degraded crude oil is not a significant threat to shallow groundwater quality. It should be <br /> noted that shallow groundwater beneath the project area is prohibited for use as domestic or <br /> ' municipal supply by the City of Tracy Municipal Code(Section 11.1.16) for administrative <br /> reasons unrelated to the presence of degraded crude/Bunker C fuel oil. <br /> 2.3 EVALUATION OF HUMAN HEALTH RISKS <br /> ' ChevronTexaco completed an extensive site assessment and human health risk assessment for <br /> the Dividend property in response to the presence of degraded crude/Bunker C fuel oil in sub- <br /> surface soil (Geomatrix, 1995). The Dividend property is located directly adjacent to the <br /> northeastern section of the WCOS project area(Figure 1). Previous assessments for the Divi- <br /> dend property indicated that the residual petroleum in soil does not pose a significant health <br /> risk to future on-site residents. Because the former pipelines are the probable source of the <br /> degraded crude/Bunker C fuel-affected soil at the Dividend property, a comparison site condi- <br /> tions within the project area to the Dividend property regarding the potential health risk posed <br /> by the residual petroleum is appropriate. <br /> ' 3.0 SOIL MANAGEMENT PLAN <br /> This management plan is intended to describe options for handling the soil affected by <br /> degraded crude oil encountered during excavation activities associated with installation and/or <br /> repairing subsurface utilities. Oil-affected soil was encountered during previous investigations <br /> at several locations along the pipeline. <br /> ' 3.1 REUSE OR DISPOSAL OF EXCAVATED SOIL <br /> Soil may be reused at the site pending appropriate approvals since the residual crude oil in soil <br /> does not pose an unacceptable risk to human health or the environment. Upon encountering <br /> ' oil-affected soil during excavation, the following steps should be taken: (1)notify <br /> ' I:\Doc_Safe\7000s\7243.011\Rev WCOS SWAM 3 <br />