Laserfiche WebLink
Awe SECOR www,secor.com <br /> 0 INTERN&ONAL 3017 Kilgore Road,Suite 100 <br /> S E C 0 R INCORPORATED Rancho Cordova, CA 95670 <br /> jrry x916-861;040ch <br /> July 27, 2007 <br /> 1 2007 <br /> HEAU <br /> Mr. Harlin Knoll <br /> San Joaquin County Environmental Health Department <br /> 304 East Weber Avenue, Third Floor <br /> Stockton, CA 95202 <br /> RE: Confirmation Soil and Groundwater Sampling Work Plan <br /> 7-Eleven Store#21756 <br /> 853 East Yosemite Avenue <br /> Manteca, CA <br /> SECOR Project No.: 77EL.21756.07.0514 <br /> Dear Mr. Knoll: <br /> This work plan was prepared by SECOR International Incorporated (SECOR) on behalf of <br /> 7-Eleven Inc. for the advancement of one direct push soil boring at 7-Eleven store #21756, <br /> located at 853 East Yosemite Avenue in Manteca, California (Figures 1 and 2). This work <br /> plan was prepared in response to the San Joaquin County Environmental Health <br /> Department (SJCEHD) letter dated June 19, 2007 requesting confirmation soil and <br /> groundwater sampling be conducted in the vicinity of existing groundwater monitoring well <br /> MW-1 at the site (Attachment A). <br /> SITE BACKGROUND <br /> On December 9, 1998, three 10,000-gallon steel single-walled USTs were removed from <br /> the site and not replaced (IT Corporation, January 1999). Six soil samples were collected <br /> from the base of the UST pit approximately 14 feet below ground surface (bgs), and two soil <br /> samples were collected from beneath the pump islands and associated fuel dispensing <br /> piping at approximately 4 feet bgs. Total petroleum hydrocarbons as gasoline (TPHg), TPH <br /> as diesel (TPHd), and benzene, toluene, ethylbenzene, and total xylenes (BTEX) were not <br /> detected above laboratory reporting limits. Methyl-tert-butyl ether (MtBE) was reported at a <br /> concentration of 0.18 milligrams per kilogram (mg/kg) in the northwest corner of the UST <br /> pit. <br /> Initial site assessment was conducted in June 1999 (IT Corporation, 1999) by advancing <br /> five push-probe borings to total depths up to 25 feet bgs. Soil samples collected during <br /> drilling contained up to 0.167 mg/kg MtBE; benzene and TPHg were not detected above <br /> laboratory reporting limits. MtBE in soil was detected in one location (GP-4) at a <br /> concentration of 0.167 mg/kg. Grab groundwater samples collected at the base of the <br /> borings contained up to 607 micrograms per liter (Ng/L) benzene, 32,200 pg/L TPHg, and <br /> 46,300 pg/L MtBE. The highest concentrations were observed in boring GP-3, located near <br /> the western end of the former dispenser island location. <br /> 1:17-EleveW-11 Stores121756(Closing)lworkplans121756 Confirmation GP 7-27-07.doe <br />