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Upgradieriw� Environmental �ultants WORKPLAN FOR EXCAVATION OF CONTAMINATED SOIL Kwikee Food Mart .2081 Country Club Boulevard Stockton,CA EXECUTIVE SUMMARY The Kwikee Food Mart is a convenience store and gasoline station located at the intersection of Country Club Boulevard and Franklin Street in Stockton,California. The station sells unleaded gasoline,which is stored in two 10,000-gallon underground storage tanks. The tanks are single-walled and by law must be removed or replaced by the end of 1998 deadline. Three groundwater monitoring wells are located on the property,and trace amounts of petroleum hydrocarbons were detected in soil samples collected from these wells when they were drilled. In addition,various constituents of gasoline have been detected in water samples from these wells.Although these chemicals are unhealthy,they have been detected in such low amounts that they are not considered hazardous by the California Department of Toxic Substances or the California Water Quality Control Board. If the presence of these hydrocarbons in the soil and groundwater is due to leaks in the tanks or their related piping,removal of the tanks will prevent further contamination.However, any residual petroleum left in the soil could constitute a minor long-term source of contamination,and should be removed. The owner of the property therefore plans to excavate and dispose of any contaminated soil that may be encountered when the tanks are removed. Excavation is an accepted and highly efficient means of eliminating potential threats to public health from contaminated or hazardous soil. After the tanks have been removed, a hazardous materials specialist will examine the excavation for evidence of contamination, such as gasoline odors or petroleum staining. If evidence of residual contamination is observed, a backhoe will be used to deepen or enlarge the excavation as . necessary to remove the contaminated soil. However, because groundwater is relatively shallow and the tanks are located close to the convenience store, the excavation is expected to be no deeper than 15 feet and probably less than 30 feet by 30 feet in area. The excavated soil will be temporarily stockpiled in a convenient location near the excavation before being loaded into dump trucks for transport to an authorized disposal facility. We anticipate that the entire project, including repaving, can be completed in three to four days. Excavation, loading, and transport of the contaminated soil should be completed within one day, but if circumstances require that the excavation be left open overnight, a .sturdy wire mesh fence will be placed around the excavation to prevent accidents. Stockton: P.O.Box 8002,Stockton, CA 95208 (209) 772-3620 Cameron Park: 3369 Kimberly Road, Cameron Park, CA 95682 (916)677-3055