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AOC Work Plans <br /> residential PRG of 23,000 mg/kg. All other analyses from all samples wei e below the applicable <br /> PRGs. PCP and TCP,analyzed in two of the samples collected in the ditc ,were also below <br /> reporting limits. <br /> AGE subsequently drilled one soil boring(DP-1)in the Western Ditch Arc a to first encountered <br /> groundwater in the vicinity of sample location DS 1 to assess the vertical a tent of contamination <br /> previously encountered in sample DS 1. One grab groundwater sample an two soil samples(10 <br /> and 15 feet bgs)were submitted for laboratory analyses for TRPH, chronui mi, lead, and zinc. <br /> TRPH was below reporting limits in both soil samples. Chromium,lead,and zinc were all within <br /> background levels(AGE, 2001). The grab groundwater sample was analy2 ed for TRPH and total <br /> metals. TRPH in the groundwater was below reporting limits while conce itrations for total <br /> chromium, lead, and zinc were 0.95, 0.17,and 2.07 mg/L,respectively. T1 Le elevated <br /> concentrations for chromium,lead,and zinc were believed to represent soi components(they were <br /> not filtered)and not representative of dissolved concentrations. Based on I he results of the <br /> December 2000 assessment,AGE determined that contamination associated with the former steam <br /> cleaning operation appeared to be limited to shallow soil(less than 5 feet b gs). <br /> In December 2001,AGE installed two additional borings(PB-5 and PB-6)in the western ditch area <br /> (Plated 4.4b)and collected soil samples at depths of 5 and 10 feet bgs and b groundwater <br /> samples from each boring. All samples were analyzed for TPHg,TPHd,TPHmo, SVOCs, <br /> formaldehyde,chromium,lead,and zinc. In addition,the 5.0 foot sample Jirom PB-5 was also <br /> analyzed for pH. <br /> TPHd and TPHmo were only detected in soil samples collected from PB-5 at maximum <br /> concentrations of 4.3 and 6.8 mg/kg respectively. Formaldehyde was detected in both borings at a <br /> maximum concentration of 43 mg/kg. Metals were also detected in both borings at concentrations <br /> Draft <br /> KB61125 workplan-ESC MACTEC Engineering and Consulting, Inc. 40 <br /> September 28,2005 <br />