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RECEIVE JUL 13 2012 EOMIIHO G. Baowry JR. ovcnxon ENVIRONMENTAL HEALTH M Er^w Ronniouez Water Boards PERMrr/SERVICES rr OR...u4ldl W.rr.N.x Central Valley Regional Water Quality Control Board 11 July 2012 Mr. Robert C. Brod John Deere Landscapes One John Deere Place Moline, IL 61265-8010 SOIL EXCAVATION COMPLETE, FORMER LESCO FACILITY, 2829 AND 2835 WEST WASHINGTON BLVD., SAN JOAQUIN COUNTY The former bulk fertilizer handling facility operated by Lesco has been vacant since 2005. In about 2007, John Deere Landscapes bought Lesco, including this facility at 2829 and 2835 West Washington Boulevard within the Port of Stockton. In 2010, John Deere removed most of the structures on the northern parcel, and in 2011, its consultant, ERM, excavated soil from the northern parcel that contained elevated concentrations of nitrate and ammonium. The description of the soil excavation event and confirmation sample results are presented in the Soil Remediation Summary Report dated May 2012, prepared by ERM. Central Valley Regional Water Quality Control Board, Central Valley Region (Central Valley Water Board) reviewed the report and concur with John Deere that the contaminated soil has been removed from the site. Soil Excavation Guided by soil sampling conducted between 2005 and 2011, John Deere excavated and disposed of about 7,800 cubic yards of soil that contained predominately nitrate and ammonium. During excavation, monitoring well MW-1 needed to be destroyed, and ERM unearthed a septic tank and a concrete vault that had not been previously identified. These three structures were removed with San Joaquin County oversight. The stormwater pond liner was removed and the pond was backfilled. The excavation work was concluded in early 2012. Confirmation Samples The lateral and vertical extent of excavations was determined by confirmation samples which met the cleanup goal of 100 mg/kg nitrogen (the sum of nitrate-as-nitrogen plus ammonium). In a few places, the cleanup goal could not be met laterally due to the potential of undermining structural features, or vertically due to the presence of groundwater. During excavation, the groundwater surface elevation varied between 5 and 7.5 feet below ground surface. In the.Soil Remediation Summary Report, Table 3 shows that if the sum of nitrate (as nitrate) plus ammonium exceeded 100 mg/kg, then additional excavation was conducted, if it was possible to do so. Based on Table 3, it appears that numerous samples contained more nitrogen than the 100 mg/kg cleanup goal. However, when the table is adjusted to count nitrate as nitrogen, instead of as nitrate, then very few of the confirmation samples exceed the 100 mg/kg cleanup goal. Of the 62 wall samples, the 3 that contained nitrogen between 128 mg/kg and 185 mg/kg were removed in subsequent excavations. As a result, none of the remaining perimeter wall samples contained nitrogen above the cleanup goal. KARL E. LONDLEY Sc D, P.E., cRAIR I PAMELA C. CREEDON P.E., BCEE, E%ECUTIVE OEEICEN 11020 Sun Center Drive#200,Rancho Cordova,CA 05070 Iwww.watarboartls.ca.gov/centralvalley C.,arn.ccea.erex