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Californiaftegional Water Quality C&trot Board <br /> `- Central Valley Region <br /> W/ Karl E. Longley, ScD, P.E., Chair <br /> Linda S. Adams Arnold <br /> Secretary for 11020 Sun Center Drive#200, Rancho Cordova, California 95670-6114 Schwarzenegger <br /> Environmental Phone (916)464-3291 • FAX(916)464-4645 Governor <br /> Protection http://www.waterboards.ca.gov/centralvalley <br /> DEDDdDD <br /> 30 September 2009 <br /> OCT 0 2 2009 <br /> Ms. Jennifer Sedlachek ENVIRONMENT HEALTH <br /> ExxonMobil Environmental Services Company PERMITISERVICES <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 Pilot Test Work Plan Addendum (Workplan Addendum) received 14 September 2009 <br /> from your consultant ETIC Engineering, Inc. (ETIC). The Workplan Addendum requests a change <br /> from the approved pump test for two groundwater extraction wells (EX-1 and EX-2) to a rising head <br /> slug test, citing data gathered during well construction and development of EX-1 and EX-2 that <br /> indicated low hydraulic conductivity (K), which may make the pump test infeasible. The Workplan <br /> Addendum states that the method to analyze the slug test will be determined following collection of the <br /> field data. <br /> The Princeton Remediation Course states a rising head slug test is appropriate for a well that is <br /> screened across the water table; that the most problematic limitation for a slug test is due to borehole <br /> wall smearing during well construction, resulting in a lower than actual K value, and that the two most <br /> popular methods for determining unconfined aquifer K are the Hvorslev and Bouwer-Rice methods. <br /> Please ask ETIC to provide additional information concerning how the method to analyze the data will <br /> be chosen, and why that decision must wait until after the slug test is completed, in an email response <br /> to me at the email address listed below by 15 October 2009. 1 will make a final determination <br /> concerning the request at that time in my response to the email. Upon approval of the Workplan <br /> Addendum, provide at least three working days notice to me prior to starting fieldwork. If you have any <br /> questions, you may contact me at (916) 464-4615, or by email at jbarton@waterboards.ca.gov. <br /> /JAMES L. L. BARTON, P.G. <br /> Engineering Geologist <br /> cc: Ms. Carmen Harms, SWRCB, UST Cleanup Fund, OSCA Account, Sacramento <br /> Ms. Margaret Lagorio, San Joaquin County Environmental Health Department, Stockton <br /> Mr. Duane and Ms. Wendy Berdt, Guido Segarini Trust, PO Box 1810, Aptos 95001 <br /> Ms. Theresa Marler, 14245 Lora Drive, #16, Los Gatos, CA 95030 <br /> Mr. Brian Campbell, ETIC Engineering, 2285 Morello Avenue, Pleasant Hill 94523 <br /> California Environmental Protection Agency <br /> �a Recycled Paper <br />