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Work Plan For A Limited Subsurface Investigation - Chevron Service Station #9-3232 October 2, 1998 the site consist of a station building with three service bays, two dispenser islands , and three 10 , 000-gallon gasoline USTs that share a common pit near the southern site boundary . Location of pertinent site features are shown on Figure 2 . PREVIOUS ENVIRONMENTAL WORK According to the data provided by Chevron, the service station was constructed in 1967 . Subsurface facilities consisted of one 5 ,000-gallon and two 10 , 000-gallon steel USTs , and one 500-gallon used oil steel UST . In August 1983 , the original USTs were replaced with three 10 ,000-gallon single-walled fiberglass USTs and one 1 , 000-gallon single-walled fiberglass used oil UST . In December 1993 , dispensers and product lines were removed . The dispensers were replaced and the product lines were upgraded from single-walled fiberglass to double-walled fiberglass . The three 10 , 000-gallon single-walled fiberglass USTs were not removed or upgraded . Touchstone Developments witnessed the removal of the subsurface facilities . Soil samples were collected from beneath the product lines and the waste oil UST remote fill pipe . Total Petroleum Hydrocarbons as gasoline (TPHg) were detected in one soil sample from beneath the product lines at a concentration of 7 parts per million (ppm) . Benzene was detected in one sample at a concentration of 0 . 81 ppm. Lead was detected in three of the five soil samples at concentrations of 5 and 6 ppm. The soil sample collected beneath the used oil UST remote fill pipe contained TPHg (3 ppm) . Total Petroleum Hydrocarbons as diesel (TPHd) were detected in this sample at a concentration of 350 ppm, and Total Oil and Grease (TOG) were detected at a concentration of 1 ,700 ppm. Trichloroethene (TCE) was also detected in this sample at a concentration of 0 . 037 ppm . SCOPE Or WORK To evaluate soil and groundwater conditions beneath the subject site , GR proposes to install four groundwater monitoring wells at the locations shown on Figure 2 . Monitoring data from other sites in the general vicinity suggest groundwater will be encountered at approximately 40 feet below ground surface (bgs) . GR ' s Field Methods and Procedures are included in Appendix A . To implement the proposed scope of work, GR proposes the following tasks : 346463.01-1 2 i