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w ' <br /> San Joaquin County <br /> Environmental Health Department DIRECTOR <br /> Donna Heran, REHS <br /> 2 �-~ 600 East Main Street <br /> Q. PROGRAM COORDINATORS <br /> { Stockton, California 95202-3029 Robert McClellon, REHS <br /> • �. Jeff Carruesco, REHS, RDI <br /> • Kasey Foley, REHS <br /> /FO <br /> Cq --.R•�j�P Website: www.sjgov.org/ehd Linda Turkatte, REHS <br /> Phone: (209) 468-3420 <br /> Fax: (209) 464-0138 <br /> August 31, 2011 <br /> Mr. Dung Thanh Phan and Ms. Nhuan Thi Phan <br /> 3524 Morningside Drive <br /> Stockton, California 95219 <br /> Subject: California Stop <br /> 2224 Manthey Road <br /> Stockton, California 95206 <br /> Dear Mr. and Ms. Phan: <br /> The San Joaquin County Environmental Health Department (EHD) has reviewed Additional <br /> Site Assessment Work Plan - June 2011, dated 29 June 2011, and Soil Vapor Extraction Pilot <br /> Test/Ozone Feasibility Work Plan, dated 12 July 2011, both prepared and submitted by your <br /> consulting firm Advanced GeoEnvironmental, Inc. (AGE) on your behalf. In Additional Site <br /> Assessment Work Plan -June 2011, AGE proposes the advancement of one on-site borehole <br /> to collect grab groundwater samples; installation of one off-site and two on-site shallow <br /> groundwater monitoring wells; and installation of two on-site deep groundwater monitoring <br /> wells to delineate the dissolved petroleum hydrocarbon plume at this site. In Soil Vapor <br /> Extraction Pilot Test/Ozone Feasibility Work Plan, AGE proposes to perform an eight-hour soil <br /> vapor extraction (SVE) pilot test followed by a six-month in-situ ozone sparge (IOS) pilot test. <br /> The EHD had directed by letter dated 30 March 2011 the submittal of a work plan to install <br /> additional wells, and the performance of an ozone bench-scale test (BST) and an SVE pilot <br /> test. <br /> Although the diagram in Figure 5 of Additional Site Assessment Work Plan - June 2011 for <br /> the proposed shallow monitoring wells illustrates a screen interval from 20 to 30 feet below <br /> surface grade (bsg), Sections 2.0 and 3.0 of this work plan describe the screen interval as <br /> between 10 and 30 feet bsg for the three proposed shallow wells, and between 70 and 80 feet <br /> bsg for the two proposed deep wells. Since all seven shallow wells currently at this site are <br /> screened between 10 and 30 feet bsg and the depth-to-groundwater measurement at the site <br /> is commonly less than 20 feet bsg, the EHD directs that the two proposed on-site shallow <br /> wells be screened between 10 and 30 feet bsg unless your consultant can provide an <br /> adequate technical justification for the 20 to 30 feet bsg screens. The shallow off-site well <br /> proposed by AGE on the east side of the Interstate-5 (1-5) south-bound on-ramp should be <br /> screened deeper than 10 to 30 feet to compensate for the additional elevation of the 1-5 on- <br /> ramp. Provide the revised screen interval for this off-site well to the EHD prior to submitting <br /> the encroachment and boring permit applications to install this well. <br /> The EHD has reviewed the locations of the two proposed deep wells and approves the <br /> installation of only the deep well, approximately 15 feet northwest of MW-1. The EHD does <br /> not believe it necessary to install the proposed deep well at the east side of the building <br />