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0 <br /> _ ' Y <br /> e.. <br /> f <br /> t <br /> grained c1ayey sand that contains occasional pebbles. The <br /> saturated zone is sound in this layer at a depth of approximately <br /> 10.5 feet below surface grade. <br /> General Hydrogeologic Setting <br /> The site lies approximately 3 miles west of the San Joaquin <br /> River and the canal systems for the Sacramento Valley. The water <br /> supply in the area is provided by the city of Tracy. The Tracy <br /> area is on the west-central flank of the Sacramento Val:-ay drainage <br /> basin. The depth to groundwater is approximately 10 feet below <br /> surface grade. The direction of groundwater flow appears to be to <br /> t'�e northeast, based on topographic and surface drainage patterns. <br /> SITE HISTORY/BF,CRGROUND <br /> The current business activity at the site is a video <br /> rental/sales store. It was reported to TFCC. that the site was <br /> formerly used as a retail gasoline service stat:ion. Approximately <br /> 60 feet of underground product lines were connected to the <br /> underground fuel storage tanks and a product elispenser area (pump <br /> island) located on the southeastern portion of the property. <br /> According to interviews with the present tanant, the USTs were <br /> removed some time in 1971. There were no known details of the <br /> tanks' removal, contents or disposal, nor were any as-built plans <br /> available for review by TECC personnel. On July 18, 1939, TECC <br /> collected 3 soil samples of the soil/water interface (saturated <br /> zone) along the perimeter of the estimated former location of tho <br /> USTs. The report of findings entitled"Limited Subsurface Soil <br /> Investigation, 275 Grantline Road, Tracy, August 21, 19891' is <br /> included in Appendix A of this work plan. The four soil samples <br /> were analyzed for Total Petroleum Hydrocarbons (as gasoline) TPH(g) <br /> EPA Method 8015 and Benzene, Toluene, Ethylbenzene and Xylenes <br /> (BTEX) EPA Met-h.od 8020. Analytical results indicated <br /> concentrations of TPH(g) above the detection levels of 1 ppm in two <br /> samples near the northeastern and northwestern corner of the <br /> building. These samples are designated B1-1 and B4-1. on the chain <br /> of c:.3tody attached to the report. <br /> TEW removed a 250-gallon UST that had last contained waste oil. <br /> This removal was accomplished on December 6, 1989. The results of <br /> the soil sampling and report of findings is contained in the March <br /> 15, 1990 TECO Proposal entitled "Proposal for Soil Excavation, Soil. <br /> Sampling, Transport/Disposal and Site Restoration, 275 Grantline <br /> Road, Tracy, California." Analytical results indicated detectable <br /> amounts of TPH(g) in two of, the three soil samples collected from <br /> the base of the UST excavation. No detectable amounts of Purgeable <br /> Halogen compounds (EPA Method 8010) were detected above detection <br /> limits nor were any TPH (as diesel) concentrations observed. Oil <br /> and Grease concentrations of 10, 310 and 20 parts per million (ppm) <br /> were indicated in the analytical results. Further excavation was <br /> recommended to the client and the San Joaquin County Public Health <br /> H:\APPS\WP51\TOM\WRKPLNW\WRRPLNW275 PACE 2 OF 5 <br /> i <br />