ARCHIVED REPORTS_XR0012077 - Laserfiche WebLink

Home Browse Search

1 L7 Unocal Service Station #6981 November 28, 1994 Site improvements consist of three product dispenser islands and two 12,000-gallon underground storage tanks (USTs) in a common excavation east of the building The building is not utilized by Unocal The former USTs were replaced with new double-walled fiberglass UM in May and June, 1988 Locations of the pertinent site features are shown on the Site Plan (Figure 2) PREVIOUS WORK In May and June 1988, RESNA Industries collected soil samples during replacement of the UST and from test pits excavated adjacent to the product dispenser islands Petroleum hydrocarbons were detected in soil samples collected from the UST excavation, product lines, and test pits Approximately 1,600 cubic yards (yd') of hydrocarbon-impacted soils were excavated and treated onsite prior to disposal Overexcavation was terminated due to the proximity of roads and structures before all hydrocarbon-impacted soils could be removed A soil vapor survey was performed to assess the extent of residual hydrocarbons in the soil beneath the site Thirteen groundwater monitoring wells, four vapor extraction wells, and one groundwater extraction well have been installed at or near the subject site These wells were installed . between January 1990 and August 1992 A vapor extraction test (VET) was performed in March 1992 to evaluate the feasibility of vapor extraction as a remedial option for soil beneath the site An aquifer pumping test was performed in August 1992 to evaluate the feasibility of utilizing groundwater extraction to remediate hydrocarbon-impacted groundwater FIELD ACTIVITIES In July and August 1994, the existing product dispenser islands and product lines were replaced by Aronson Engineering of Sacramento, California, and a VES installed by Red Horse Constructors of San Rafael, California, and Gettler-Ryan Inc (G-R) of Dublin, California On July 22, 1994, GSI was present at the subject site to collect soil samples from areas adjacent to the product dispenser islands A GSI geologist returned to the site on August 2, 1994, to collect samples of stockpiled soil generated during trenching for the new product lines and remedial VES, and to collect samples of drummed soil generated during the installation of vapor extraction wells VW-5 and VW-6 by RESNA Finally, GSI and G-R were present at the subject site on September 22, 1994, to collect influent and effluent airstream samples during VES startup 4855701-1 2 GeoStrategies Inc.