ARCHIVED REPORTS_XR0009304 - Laserfiche WebLink

Home Browse Search

✓ice=� Geomatrix �• ammonia The Site is surrounded by industrial activities associated with the Port to ' a distance of at least 1,700 feet (Figure 1) The Site is anticipated to continue to be used for industrial or heavy industrial purposes in the future ' 2 Site Geology and Hydrogeology. The subsurface geology in this area consists of a thick sequence of alluvial deposits which overlie sedimentary rocks Groundwater beneath the Site is confined to semi-confined During the period of record, depth to ' water measured in the monitoring wells at the Site has ranged from about 9 to 14 feet bgs Seasonal fluctuations in the water table have ranged from about 2 to 4 feet The estimated horizontal flow of shallow groundwater at the Site has been ' predominantly to the south 3 Sensitive Potential Receptors. No water supply wells have been identified within ' 2,000 feet of the Site The nearest surface water body is the Stockton Deep Water Channel, which is located approximately 1,000 feet north of the Site Groundwater monitoring data indicate that shallow groundwater beneath the Site generally flows to the south, away from the Stockton Deep Water Channel The San Joaquin River is located about 4,000 feet southwest of the Site ' 4 Well Survey A survey conducted in 1999 indicated that no municipal or drinking water supply wells were identified within 2,000 feet of the Site (Ross, 1999b) Geomatrix conducted a recent search of California Department of Water Resources (DWR) files maintained by DWR personnel in May 2006 Results of the new search were consistent with findings of the 1999 survey No municipal or drinking water supply wells were identified within 2,000 feet of the Site 1 5 Site Map. A scaled map of the Site is shown on Figure 2 This map shows the former UST area, excavation and sample locations, boring and monitoring well ' locations, groundwater elevation contours, buildings, streets, and estimated extent of total petroleum hydrocarbons quantified as gasoline (TPHg) in groundwater ' 6 Site Lithology. Boring logs and cross sections showing site lithology were provided in a report previously submitted to the EHD (Geomatrix, 2003) Geologic cross sections (Figures 3 and 4) illustrate shallow lithology below the Site ' Locations of the cross sections are included on Figure 2 The shallow soil from the ground surface to about 10 feet bgs at the Site generally comprises fill sand Underlying the shallow soil is a clay and/or silt layer to a depth of about 20 to ' 32 feet bgs This layer is generally dark greenish gray in color, indicating reducing conditions ' 7 Excavated Soil. Approximately 180 cubic yards of affected soil were excavated and removed from the Site in 1988 during the removal of the USTs ' 8 Groundwater Monitoring Wells. Groundwater samples and groundwater level measurements are collected in six existing groundwater monitoring wells (MW3-1 through MW3-6) at the Site (Figure 2) These wells will be decommissioned in ' 116000s16437 0001Archive16437-041 doc 2