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r � <br /> Ms.Amy Terrell ERM-West,Inc. <br /> 18 March 2011 <br /> Page 2 <br /> PROPOSED INVESTIGATION AND MONITORING ACTIVITIES <br /> The results of previous investigations indicated that combined <br /> concentrations of ammonia and nitrate are present in soil at <br /> concentrations above the established protection of groundwater soil <br /> screening level(PGW SSL) of 100 milligrams per kilogram(mg/kg). <br /> With the exception of two locations (SB-9 and SB-25), combined <br /> concentrations of ammonia and nitrate above the PGW SSL were <br /> primarily detected in soil in proximity to the Former Mixing Area,Truck <br /> Loadout, and Former Liquid Tank Farm. The presence of the Former <br /> Mixing Area building and the concrete slab of the Former Liquid Tank <br /> Farm precluded the collection of samples within the areas occupied by <br /> those structures during previous investigations. <br /> Additionally,lead above its residential Regional Screening Level(RSL) <br /> and California Human Health Screening Level(CHHSL), but below the <br /> industrial RSL,was detected in a sample collected at a depth of 2 feet <br /> below ground surface (bgs) at one location(SB-8)in the northwest corner <br /> of the property (Figure 2). <br /> As previously indicated, the Former Mixing Area building and the <br /> concrete slab of the Former Liquid Tank Farm were demolished and <br /> removed from the site in November 2010. Therefore, Deere proposes to <br /> conduct additional soil sampling to address the data gaps in ammonia <br /> and nitrate results in those areas and to further evaluate the presence of <br /> lead at location SB-8. Soil samples will be collected from 25 soil borings <br /> (SB-27 through SB-51) at the site (Figure 2). Soil samples will be collected <br /> from 13 borings(SB-30 through SB-42) within the area previously <br /> occupied by the Former Mixing Area building and 9 borings (SB-43 <br /> through SB-51)within the area of the Former Liquid Tank Farm to <br /> evaluate the presence of ammonia and nitrate at concentrations above <br /> their combined PGW SSL. Soil samples will be collected from three <br /> borings (SB-27,SB-28, and SB-29) in the vicinity of boring SB-8 to <br /> characterize the extent of lead in soil. <br /> Additionally, groundwater samples will be collected from the four <br /> on-site monitoring wells (MW-1 through MW-4) to obtain current <br /> groundwater concentration data(Figure 2). <br /> Permitting and Utilities Clearance <br /> Prior to initiating field activities,necessary permits will be obtained from <br /> San Joaquin County Environmental Health Department(SJCEHD). This <br /> Workplan, a master file record information form, site mitigation fees, and <br />