Laserfiche WebLink
Cheaper#76, 890 N. Main St.,Manteca,Calzfonua <br /> December 22,1995 <br /> Page 18 <br /> iX1. Conclusions for QjIle closure <br /> • Potential sources of petroleum hydrocarbon release at this site were the <br /> underground storage tanks removed in 1987. The existing tanks and piping are <br /> double-walled steel with fiberglass coating and an automatic monitoring and <br /> alarm system <br /> • Soil sampling found petroleum hydrocarbon release near the underground <br /> storage tank location. <br /> • Approximately 650 cubic yards of soil containing petroleum hydrocarbons were <br /> excavated and removed off site. <br /> • Three monitoring wells were installed in 1987, and a fourth in 1991. <br /> Groundwater was monitored 14 times (12 times four wells) from March, 1987 to <br /> July, 1995. Shallow groundwater is about 20 to 29 feet below grade, averaging <br /> 24 35 feet and the gradient is toward the southwest. <br /> • Groundwater monitoring sample results were non-detect for TPH-g. A minimal <br /> amount of Benzene was detected from the samples taken when the wells were <br /> installed, and minute amounts Benzene, Toluene, Ethylbenzene and Xylenes <br /> were detected from the samples taken in January, 1995. <br /> • Calculations of gasoline remaining on-site show less than one gallon. This <br /> gasoline has been in place since before 1987, and has undergone natural physical <br /> and biological degradation for at least 8 years. <br /> XII. Recommendations <br /> Other than properly closing the four monitoring wells, no additional work is <br /> recommended for this site. <br /> i <br /> Parker Environmental Services, 190 East 7th Street, Pittsburg, CA 94565-2317 <br /> Phone (510) 439-1024 Fax (510) 439-2566 <br />