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• • `'\ EDMUND
<br /> o ELAND G. 6ec.N JR.
<br /> RECEIVED(, �� a
<br /> #..,..NN,. AUG 0.2 2012 v M0CNoxax,ouF=
<br /> Water Boards ` —F Ao..FNr..
<br /> ENVIRONM
<br /> Central Valley Regional Water Quality Control Board PERMIT/SERVICES
<br /> Ms. Jennifer Sedlachek 1 August 2012
<br /> ExxonMobil Environmental Services Company
<br /> 4096 Piedmont Ave, #194
<br /> Oakland, CA 94611
<br /> DOCUMENT REVIEW, FORMER MOBIL STATION 99CAS (AKA MARLER PROPERTY,
<br /> (AKA JH GRIFFIN MOBIL SERVICE), 75 EAST ALPINE AVENUE, STOCKTON,
<br /> SAN JOAQUIN COUNTY (CASE# 390857)
<br /> 1 reviewed the Groundwater Monitoring and Remediation Status Report, Second Quarter 2012
<br /> (Report) received 30 July 2012 from your consultant Cardno ERI. On 3&4 May 2012, maximum
<br /> groundwater concentrations were total petroleum hydrocarbons as gasoline (TPHg),
<br /> 110,000 micrograms per Liter (ug/L); TPH as diesel (TPHd), 7,400 ug/L; benzene, 5,800 ug/L;
<br /> toluene, 70,000 ug/L; ethylbenzene, 3,700 ug/L; and xylenes, 22,000 ug/L. Depth to
<br /> groundwater varied from 30' below ground surface (bgs) to 32' bgs. Groundwater flow direction
<br /> varied from northeast (shallow zone) to east (deep zone).
<br /> The soil vapor extraction (SVE) ran from 27 March 2012 to 6 June 2012 and removed
<br /> 1,680.88 lbs. of total petroleum hydrocarbons as gasoline in 19.4 days of operation (high levels
<br /> in water condensate tank caused four shutdowns).
<br /> The Report recommends changing the frequency for offsite monitoring wells MW-6 through
<br /> MW-8 and DW-4 from quarterly to annual due to a history of non-detects, and MW-1, MW-3 and
<br /> DW-2 from quarterly to semi-annual due to a history of very low contaminant concentrations.
<br /> The remaining monitoring wells are adequate to continue quarterly monitoring of the
<br /> groundwater plume and to assess the effectiveness of the SVE system.
<br /> I concur with the recommendations, with annual monitoring during the first quarter of each year
<br /> and semi-annual monitoring during the third quarter of each year. If you have any questions,
<br /> u may contact meat 0916) 464-4615, or by email at jbarton@waterboards.ca.gov.
<br /> JAMES L. L. BARYON, P.G.
<br /> Engineering Geologist
<br /> cc: Nuel Henderson, San Joaquin County Environmental Health Department, Stockton
<br /> Duane and Ms. Wendy Berdt, Guido Segarini Trust, PO Box 1810, Aptos 95001
<br /> Theresa Marler, 14245 Lora Drive, #16, Los Gatos, CA 95030
<br /> Arthur Lavagnino, 1466 W. Magill Ave., Fresno 93711
<br /> Scott Conner, First Baptist Church of Stockton, 3535 N. EI Dorado St., Stockton 95204
<br /> Jennifer Lacy, Cardno ERI, 601 N. McDowell Blvd., Petaluma 94954
<br /> KARL E. LONGLEY SOD, P.E., CHAIR I PAMELA C. CREEDON P.E.. DCEE. EXECUTIVE OFFICER
<br /> 11020 Sun Center Drive#200,Rancho Cordova,CA 95870 1 www.waterboartle.ca.gov/centralvalley
<br /> C',nrc.c.ro rnrrn
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