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California Ifgional Water Quality Coreol Board <br /> Central Valley Region <br /> Karl E. Longley, ScD, P.E., Chair a <br /> Linda S. Adams Arnold <br /> Secretary for 11020 Sun Center Drive#200, Rancho Cordova, Qalifornia 95670-6114 Schwarzenegger <br /> Environmental Phone (916)464-3291 • FAX (916) ����� Governor <br /> Protection http://www.waterboards.ca.gov/cen <br /> Ms. Jennifer Sedlachek UtL 2 4 200922 December 2009 <br /> ExxonMobil Environmental Services Company ENVIRONMENT HEALTH <br /> 4096 Piedmont Ave, #194 PERMIT/SERVICES <br /> Oakland, CA 94611 <br /> DOCUMENTS 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 Slug Test Report (Report) and the Work Plan for Dual Phase Extraction Pilot Test <br /> (Workplan), both received 21 December 2009 from your consultant ETIC Engineering, Inc. (ETIC). <br /> The Report stated the Bouwer-Rice method was used for rising and falling head slug testing of two <br /> existing groundwater extraction wells (EX-1 and EX-2); the data indicated an average of both wells <br /> hydraulic conductivity (K) of 7.38x10-" centimeters-persecond-which-correlates to a silt or fine sand; <br /> and recommended conducting a dual phase extraction (DPE) pilot test for soil vapor and groundwater <br /> contamination. The Workplan proposes a one day DPE pilot test, to be scheduled for January 2010, <br /> with a DPE pilot-test report to be submitted by 28 February 2010. Vacuum will be initially applied <br /> individually to EX-1 and EX-2 in a step test, using 5 inches of mercury increments increasing up to the <br /> maximum vacuum achieved for each extraction well, while measuring temperature, vapor flow and <br /> extracted liquid flow from the extraction well. Changes in water in nearby monitoring wells MW-2, <br /> MW-4 and MW-5 and the unused extraction well, with the vacuum measured in vapor extraction wells <br /> VEW1 through VEW 4, will be used to determine the radius of influence for DPE. Upon conclusion of <br /> the step test, the DPE pilot study equipment will then be modified to extract soil vapor and groundwater <br /> simultaneously from EX-1 and EX-2 as a constant vacuum test, while measuring changes in water <br /> levels and vacuum as stated above, and collecting soil vapor and groundwater samples while recording <br /> photo ionization detector (PID) readings of the vapor stream, to calculate the mass of petroleum <br /> hydrocarbons extracted during the pilot test. <br /> The Workplan is approved with the condition that field readings by PID be conducted during the step <br /> test, to provide an indication which extraction well is most effectively removing petroleum hydrocarbons <br /> under DPE. Please provide me at least three working days notice prior to starting fieldwork. If you <br /> have any questions, you may contact me at (916) 464-4615, or by email at <br /> j rtonawaterboards.ca.gov. <br /> JAMES L. L. BARYON, P.G. <br /> Engineering Geologist <br /> cc: Ms. Carmen Harms, SWRCB, UST Cleanup Fund, OSCA Account, Sacramento <br /> Mr. Nuel Henderson, 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 /> Qi Recycled Paper <br />