WORK PLANS - Laserfiche WebLink

Home Browse Search

' GEOMATRIX the residual crude oil. The residual crude oil may also contain low(less than 1 mg/kg) concen- trations of non-carcinogenic polyaromatic hydrocarbons (PAHs). ' The vertical extent of petroleum-affected soil is typically between 5 and 25 feet bgs in the vicinity of the project area. Soil affected by degraded crude/Bunker C fuel oil is typically constrained to within 50 feet of the right-of-way but may be present as far as 180 feet laterally from Byron Road. 2.2 SITE HYDROGEOLOGY AND GROUNDWATER QUALITY The subsurface soil within the project area is predominantly silt and clay with isolated sandy ' lenses to a depth of at least 20 feet. The recent depth to the water table is approximately 5 to 10 feet bgs and groundwater generally flows to the north- northeast in the project vicinity. Based ' on the results of the groundwater investigations performed at the subject sites,the Regional Water Quality Control Board(RWQCB), the Department of Toxic Substance Control (DTSC), ' and/or the San Joaquin County Environmental Health Department (EHD) have determined that the degraded crude oil is not a significant threat to shallow groundwater quality. It should be noted that shallow groundwater beneath the project area is prohibited for use as domestic or ! municipal supply by the City of Tracy Municipal Code (Section 11.1.16) for administrative reasons unrelated to the presence of degraded crude/Bunker C fuel oil. ' 2.3 EVALUATION OF HUMAN HEALTH RISKS ChevronTexaco completed an extensive site assessment and human health risk assessment for the Dividend property in response to the presence of degraded crude/Bunker C fuel oil in sub- surface soil (Geomatrix, 1995). The Dividend property is located directly adjacent to the northeastern section of the WCOS project area(Figure 1). Previous assessments for the Divi- dend property indicated that the residual petroleum in soil does not pose a significant health risk to future on-site residents. Because the former pipelines are the probable source of the degraded crude/Bunker C fuel-affected soil at the Dividend property, a comparison site condi- tions within the project area to the Dividend property regarding the potential health risk posed by the residual petroleum is appropriate. ' 3.0 SOIL MANAGEMENT PLAN This management plan is intended to describe options for handling the soil affected by ' degraded crude oil encountered during excavation activities associated with installation and/or repairing subsurface utilities. Oil-affected soil was encountered during previous investigations at several locations along the pipeline. 1 \\oak1\deptdata\Doc_Safe\6000s\6447.006\WC0SSMP.doc 3