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°uuuxu O.S.aw J. <br /> awnnorv_ <br /> ..........�0 <br /> eec eYPn. ePanmuez <br /> Water Boards <br /> Central Valley Regional Water Quality Control Board <br /> 30 October 2014 <br /> Mr. Sergio Morescalchi Mr. Dave Patten <br /> Atlantic Richfield Company Chevron Environmental Management Company <br /> P. O. Box 1257 6101 Bollinger Canyon Road, BR1X 5222 <br /> San Ramon, CA 94583 San Ramon, CA 94583 <br /> Mr. Perry Pineda Ms. Kacey Fung <br /> Shell Oil Products US Bimbo Bakeries USA, Inc. <br /> 20945 S. Wilmington Ave. 8550 W. Bryn Ave., Suite 1000 <br /> Carson, CA 90810 Chicago, IL 60631. <br /> ADDENDUM to DATA GAP ASSESSMENT WORK PLAN, STOCKTON CHARTER WAY <br /> COMMINGLED PLUME SITE, 440, 441, 508 WEST CHARTER AND 1444 SOUTH LINCOLN <br /> STREET, STOCKTON, SAN JOAQUIN COUNTY <br /> The California Regional Water Quality Control Board, Central Valley Region (Central Valley <br /> Water Board) staff reviewed the 15 October 2014 Addendum to Data Gap Assessment Work <br /> Plan (Work Plan Addendum). The Work Plan Addendum was prepared by Stantec Consulting <br /> Services, Inc. (Stantec) on behalf of Atlantic Richfield Company, Chevron Environmental <br /> Management Company (Chevron), Shell Oil Products US (Shell), and Bimbo Bakeries USA, <br /> Inc., for the Stockton Charter Way Commingled Plume. Stantec proposes to properly destroy <br /> 17 monitoring wells and install 13 new monitoring wells to further delineate petroleum <br /> hydrocarbon impacts and fill existing data gaps. A revised Gantt Chart project schedule was <br /> provided separately on 9 September 2014. 1 concur with the list of wells proposed to be <br /> destroyed and the list of new wells to be installed with minor modifications as provided below. <br /> Comments: <br /> 1. The target screened intervals proposed in Table 2 of the Work Plan Addendum are <br /> generally appropriate for investigation at this Site. However, the Geologist in the field <br /> should understand the objectives for the investigation such that, water table (A zone) <br /> wells should be screened across the water table interface with about 5 feet of screen <br /> above the current water level and 10 feet of screen below the water table to allow for <br /> fluctuations in water levels. B, C and D zone screen intervals should target higher <br /> permeable sand zones. If these zones are not encountered at the exact depth specified <br /> in Table 2, drilling should continue for at least an additional 10 - 15 feet in each boring to <br /> assure the target sand zone does not occur at that location. The best approach may be <br /> to drill the deepest wells first so the presence of sand zones may be noted in the drillers <br /> log before constructing the shallower well(s). <br /> KAnL E. LONoLEY SCD, P.E.,CHAIR I PAMELA C. CREEOON P.E., BCEE,Es¢cunvc orriocrt <br /> 11020 Sun Center Drive#200,Rancho Cordova,CA 95610 1 www.weterboard$.ce.gov/centmWelley <br /> RECEIVED OCT 3 12014 <br /> �)nICYGtIO IPHa <br />