ARCHIVED REPORTS_XR0002675 - Laserfiche WebLink

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' 45 E Harding Way, Stockton, California September 1, 1993 Chevron USA Products Company Page 2 On February 24, 1988, four fiberglass underground storage tanks were excavated and removed Sod samples were collected from beneath individual tanks and analyzed Only one sample, from beneath the ' used-oil tank, contained 26 ppm high-boiling-point hydrocarbons However, samples from the sod pile contained up to 490 ppm low-boiling-paint hydrocarbons, 28 ppm toluene, and 26 ppm xylenes ' On November 7-15, 1988, six boreholes were drilled, as sampled, and completed groundwater P p ' monitoring wells Soil samples collected from MW-4 (Figure 2) contained benzene concentrations up to 9 6 ppm and total petroleum hydrocarbons (TPH) concentrations up to 3,300 ppm TPH concentrations In soil samples from all other well borings were below the detection limit of 1 ppm Groundwater ' samples collected from wells MW-1 through MW-6 In November 1988 contained TPH concentrations as high as 9,300 parts per billion (ppb) and 6,800 ppb from MW-3 and MW-4 respectively 1 In January 1989, three additional underground storage tanks were removed One of the tanks, ' discovered while drilling MW-5 in November 1988, still contained product Seven soil borings were drilled and sampled on January 23 through February 7, 1989 Two of the borings were converted to groundwater monitoring wells, and the remaining five borings were converted to vadose monitoring wells Hydrocarbon impacted sods were encountered in V-3, V-4, and V-5 ' On April 24, 1989, a soil vapor extraction test on V-3, V-4, and V-5 revealed total volatile hydrocarbons (TVH) concentrations from 4,500 to 16,000 ppm Operation of a vapor extraction and treatment system ' (VETS) began on November 15, 1990 On July 16, 1991, an additional sod boring was drilled at the site in the former tank field and converted Into a groundwater monitoring well (MW-9) ' On June 29, 1993, two additional soil borings were drilled lust east of the site in EI Dorado Avenue and were converted into groundwater monitoring wells (MW-12 and MW-13) The drilling results and ' Installation of these two wells are described In this report ' 2 1 QUARTERLY GROUNDWATER MONITORING AND SAMPLING ' The groundwater beneath the site was monitored and sampled at quarterly intervals from January 1989 through July 1993, however, several of the monitoring wells went dry during the recent drought A historical summary of a monitoring and sampling data are summarized in Table 2 GROUNDWATER 3399EAR RPT TECHNOLOGY