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California egional Water Quality C*rol Board <br /> Central Valley Region <br /> Katherine Hart, Chair ° <br /> 11020 Sun Center Drive,#200,Rancho Cordova,California 95670-6114 <br /> Linda S.Adams (916)464-3291 • FAX(916)464-4645 Edmund G.Brown Jr. <br /> Acting Secretary for http://www,w terboards.ca.govlcentralvalley Governor <br /> Environmental Protection <br /> RECEIVE® <br /> 7 July 2011 <br /> JUL i} �, ! <br /> Ms. Daisy Wei, P.E. EWRONMENTALHEALTH <br /> CH2M HILL PERMIT/SERVICES <br /> 155 Grand Ave Suite 800 <br /> Oakland, CA 94612-3767 <br /> CONDITIONAL CONCURRENCE WITH 10-YEAR SAMPLING EVENT AND <br /> ADDITIONAL INVESTIGATION WORK PLAN, KOPPEL STOCKTON TERMINAL, <br /> 2025 W. HAZELTON AVE., SAN JOAQUIN COUNTY <br /> California Regional Water Quality Control Board, Central Valley Region (Central Valley <br /> Water Board) staff reviewed the June 2011 Ten-Year Sampling Event and Additional <br /> Investigation at Former Bagging Plant Work Plan (Sampling Work Plan), prepared by <br /> CH2M Hill. The Sampling Work Plan proposes soil and groundwater samples to <br /> evaluate the extent of nitrate pollution identified in monitoring well KP-3, and proposes <br /> soil sampling to document the influence that phytoremediation is having on nitrogen <br /> concentrations in soil. As discussed below and as transmitted in a 1 July 2011 email to <br /> Ms. Daisy Wei of CH2M Hill, Central Valley Water Board staff conditionally concur with <br /> the Sampling Work Plan, provided that nothing is disposed of in a borehole. <br /> 10-Year Phytoremediation Review <br /> In 2000, Koppel Stockton implemented full scale phytoremediation to remove nitrate <br /> and ammonium from soil and shallow groundwater at the 2025 West Hazelton Avenue <br /> site in Stockton. As outlined in the February 2000 Remedial Action Plan, prepared by <br /> CH2M Hill, Koppel Stockton is preparing to conduct the 10-year review of the progress <br /> of phytoremediation. This review includes soil sampling to assess the change in <br /> concentration of nitrogen in the soil column. <br /> In the Sampling Work Plan, Koppel proposes to replicate the soil sampling strategy that <br /> was used in the 3-year and 5-year reviews. From each of 7 areas, 8 soil samples will <br /> be composited from each of 3 depths and analyzed for nitrogen and pH. <br /> In 2006, soil samples could not be obtained from the area north of the warehouse at all <br /> the targeted depths, due to subsurface compaction preventing the advancement of the <br /> hand auger. It is important for assessing the progress of the soil remediation to obtain <br /> soil samples from the targeted depths. Therefore, Koppel may shift the sample location <br /> within the area north of the warehouse if it is necessary in order to reach the targeted <br /> depths. <br /> California Environmental Protection Agency <br /> cliRecycled Paper <br />