ARCHIVED REPORTS XR0001482 - Laserfiche WebLink

Home Browse Search

rA 440 West Charter Way, Stockton, California September 16, 1992 Texaco Environmental Services Page 1 1 0 INTRODUCTION This report describes the installation of four nested vapor extraction wells, and the results of a soil vapor extraction test performed at the site referenced above In addition, a vapor extraction system design is presented within 20 BACKGROUND Hydrocarbon impacted soil has been confirmed and defined beneath the site by soil samples that were collected from fifteen soil borings Seventy-nine soil samples were submitted to state certified laboratory for analyses of benzene, toluene, ethylbenzene and xylenes (BTEX), and total petroleum hydrocarbons-as-gasoline (TPH-G) Selected samples were also analyzed for total petroleum hydrocarbons-as-diesel (TPH-D) and for total oil and grease (TOG) Of the 79 soil samples analyzed, 15 samples contained detectable concentrations of petroleum hydrocarbons ranging in concentration from 2 to 2,500 parts per million (ppm) TPH-G Nine samples contained benzene concentrations ranging from 1 to 11 ppm No TPH-D or TOG were detected by laboratory analyses Based on the analytical results, hydrocarbon impacted sods beneath the site are confined to the northeastern part of the property It is not known how far the impacted soil extends beneath Charter Way (Figure 1) Further subsurface exploration is not feasible since Charter Way is State Route 4 and Caltrans will not permit borings in the right- of-way The impacted sods are encountered at a depth of 15 feet below ground surface (BGS) and extend to the water table at approximately 39 feet BGS These soils consist mainly of clays from 15 to 30 feet BGS and grade to silt and fine silty sand at depths below 30 feet BGS Figures 2 and 3 present generalized geologic cross sections of the subsurface soils and the approximate extent of adsorbed hydrocarbons The volume of impacted soil has been estimated at approximately 3,000 cubic yards with average concentrations of adsorbed hydrocarbons ranging between 500 and 1,000 ppm Assuming a soil density of 2,900 pounds per cubic yard, the weight of hydrocarbons in the soil is between 4,350 and 8,700 pounds A sod vapor extraction pilot test was performed on May 21, 1991 to determine if soil venting could be used to remediate the subsurface sods Existing MW's were used as vapor extraction points during the test, and vapors were extracted using a 1 5-horsepower (hp) regenerative GROUNDWATER �' ; TECHNOLOGY