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California Regional Water Quality,*control Board: <br />Central Valley Region <br />Steven T. Butler, Chair <br />t,,,l J Gray Dais <br />Winston H. Hickox <br />Secretaryfor Sacramento Main Office Governor <br />Environmental Internet Address: http://wtivw.swreb.ca.gov/—rw•gcb5 <br />Protection 3443 Routier Road, Suite A, Sacramento, California 95827-3003 <br />Phone 916 255-3000 • FAX 916) 255-3015 <br />24 March 2000 <br />Mr. Harlin Knoll <br />Senior Registered Environmental Health Specialist <br />San Joaquin County Environmental Health Division <br />304 East Weber Avenue <br />Stockton, CA 95202 <br />1 7 <br />REQUEST FOR INTERINI REMEDIATION, FORMER CHEVRON SERVICE STATION #9-5773, <br />301 WEST KETTLEMAN LANE, LODI, SAN JOAQUIN COUNTY <br />During our 22 March 2000 meeting regarding the Chevron Service Station #9-5775 (Chevron), we <br />discussed the 1 March 2000 groundwater monitoring results provided by Gettler-Ryan Incorporated <br />(GRI). Groundwater samples in extraction well EX -1 contained up to 51,000 µg/1 of TPHg, 39,000 µg/1 <br />of benzene, 1,000 µg/1 of toluene, 1,800 µg/1 ethyl benzene, 1,300 µg/1 of xylenes, 720,000 µg/1 MtBE, <br />18,000 µg/1 ETBE, and 6,000 µg/1 TAME. A deeper monitoring well was installed at the southwest <br />corner of the site, and TPHg, benzene, and MtBE were detected at 160 µg/l, 67 µg/1, and 250 µg/1, <br />respectively during the 1 March 2000 sampling event. <br />According to the 2 November 1999 Offsite Source Survey (OSS) prepared by GRI, the USTs were <br />removed in August 1998, and all aboveground and subsurface facilities have been removed. The site is <br />currently an unpaved, vacant lot. The OSS report also identified a City of Lodi Municipal Well on South <br />Hutchins Street (Well 12) approximately 500 feet southwest of the subject site. In October 1999, GRI <br />placed data loggers in two on-site monitoring wells for a 3 -day period and recorded fluctuation changes <br />corresponding to pumping of Well 12. GRI, therefore, concluded that the shallow groundwater zone is <br />in communication with the municipal well. <br />Based on the high concentrations of petroleum hydrocarbons in groundwater, and the proximity and <br />communication with Well 12, this investigation is considered a high priority. Chevron must start site <br />remediation immediately to reduce the extent and concentration of site contamination. Chevron must <br />complete the following: <br />• Install and continuously operate an interim pump and treat system in the area of the highest <br />groundwater contamination by 24 April 2000. The pump and treat system must stabilize the <br />groundwater plume to prevent movement of contamination toward Well 12. <br />Chevron must sample and analyze Well 12 on a monthly basis for TPHg, BTEX, and fuel <br />oxygenates. <br />California Environmental Protection Agency <br />�d Recycled Paper <br />