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Californieegional Water Quality Cool Board <br /> Central Valley Region <br /> Katherine Hart, Chair <br /> 11020 Sun Center Drive,#200,Rancho Cordova,Califomia 95670-6114 <br /> 4643291 •FAX( )4 5 <br /> Matthew Rodriquez htip://www.waterboards,ca.gov/centmlvallcy EC E M <br /> r. <br /> Secrelarvfor <br /> Environmental Proleclian DEC 0 � 2011w <br /> 2 December 2011 ENVIROMIEWAL <br /> PER+ IT/SERVICES HEALTH <br /> CH2M HILL <br /> Attn: Daisy Wei, P.E. <br /> 1737 N. First Street, Ste. 300 <br /> San Jose, CA 95112-4524 <br /> REVIEW OF TEN-YEAR EVALUATION, KOPPEL STOCKTON TERMINAL, 2025 WEST <br /> HAZELTON AVE., SAN JOAQUIN COUNTY <br /> California Regional Water Quality Control Board, Central Valley Region (Central Valley Water <br /> Board) reviewed the October 2011 Ten-Year Evaluation and 2011 Annual Groundwater <br /> Monitoring Report (Ten-Year Report) prepared by CH2M Hill for the Koppel Stockton Terminal. <br /> At the Koppel Stockton Terminal, the consortium of owners and operators implemented <br /> phytoremediation in 2000 to remove nitrate and ammonium from soil and shallow <br /> groundwater. In 2011, the tree species include Hybrid Poplars, Sycamore Maple, Sycamore, <br /> Fruitless Mulberry, Paulownia, Willow,Black Locust, Sour Gum, and Water Gum. <br /> As discussed below, the Ten-Year Report shows that nitrogen concentrations in soil and <br /> groundwater have generally decreased since 2000, although some areas still retain high <br /> nitrogen concentrations. As a result of the high concentrations, possible sources of nitrogen <br /> concentrations in monitoring well KP-3 were investigated. <br /> Nitrogen in Groundwater <br /> South of the warehouse, nitrogen concentrations in shallow groundwater declined from <br /> roximately 300 mglL in 2006. In 2011, these Nlstill <br /> approximately 800 mg/L in 1999 to app <br /> area, <br /> contain approximately 300 mg/L of nitrogen. East of the warehouse, in the bagging plant <br /> nitrogen concentrations have been stable in monitoring well TG-4 at approximately 300 mg/L, <br /> but began increasing in monitoring well KP-3 from approximately 400 mg/L in 2006 to <br /> approximately 1,000 mg/L in 2011 . The data suggest that with the exception of KP-3, the <br /> phytoremediation has reached a plateau for nitrogen removal from groundwater. <br /> Downgradient of the phytoremediation plantings, groundwater has generally contained less <br /> than 60 mg/L nitrogen since 2000. Upgradient concentrations of nitrogen are approximately <br /> 200 mg/L. <br /> Nitrogen in Soil <br /> In soil the reductions of nitrogen are significant. The Ten-Year Report presents composited <br /> soil data from regular 5-year soil sampling events, in which nitrogen concentrations as high as <br /> 900 mg/kg in shallow soil in 2000 have declined to 16 mg/kg in 2010. North and south of the <br /> warehouse and beneath the stormwater ponds, nitrogen concentrations in the composited soil <br /> samples at four to six feet below ground surface have declined significantly in the past ten <br /> California Environmental Protection Agency <br /> 0d Recycled Paper <br />