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. � I ET TL ER - RYAN INC . P 19S9 ENVIRONMENTAL HEALTH DIVISION 304 E. Weber Ave. Third Floor P. O. Box 388, Stockton CA 95201 -0388 January 21 , 1999 Approved �$( Denied ❑ Mr. Brett Hunter Conditions Chevron Products Company P .O. Box 6004 Date by_ „_ . San Ramon, California 94583 Subject: Contingency Work. Plan For Excavation of Soil at Chevron Station #9-3232, 8660 Lower Sacramento Road, Stockton, California. Mr. Hunter: At the request of Chevron Products Company (Chevron), Gettler-Ryan Inc. (GR) has prepared this Contingency Work Plan in anticipation of excavating soil to evaluate extent of hydrocarbon-impacted soil if detected in compliance samples following removal of the underground storage tanks (USTs) and associated piping atthe subject site (Figure ] ). It is our understanding that the subject site is tentatively scheduled to be demolished and associated facilities removed on February 25, 1999. A new retail station is tentatively scheduled to be constructed starting on March 21 , 1999, BACKGROUND The site is currently a Chevron Service Station, with a station building, two dispenser islands, three gasoline USTs, and used oil UST. Pertinent site features are shown on Figure 2. According to Chevron records, the service station was constructed in 1967. The original facilities consisted of one 5,000-gallon and two 10,000-gallon steel USTs, and one 500-gallon used oil steel. PREVIOUS ENVIRONMENTAL WORK Ln August 1983, the original USTs were replaced with three 10,000-gallon single-wall fiberglass USTs and one 1 ,000-gallon single-wall fiberglass used oil UST. In December 1993 , the dispensers were replaced and the product lines were upgraded from single-wall fiberglass to double-wall fiberglass. Soil samples collected beneath the former product lines contained a maximum concentration of total petroleum hydrocarbons as gasoline (TPIIg) and benzene at 7 and 0 .81 parts per million (ppm), respectively. The maximum lead concentration was 6 ppm . A soil sample collected beneath the former used oil remote fill line contained TPI-Ig ata ppm, total oil & grease (TOG) at 1 ,700 ppm, TPI-I as diesel (TPHd) at 350 ppm, and trichloroethene (TCE) at 0 . 037 ppm . In October 1998, GR drilled three soil borings and installed groundwater monitoring wells in each boring. Well locations are shown on Figure 2. The soil samples analyzed from borings MW- 1 and MW-3 did not contain detectable concentrations of TPHg, BTEX, or MtBE with the exception of tine sample from well MW-3 at 49.5 feetbsg. This sample contained TPHg and benzene at a concentration C1193232.WP2 346463.02 6747 Sierra Court , Suite J Dublin , California 94568 ( 925 ) 551 - 7555