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KLEINEELDER Approximate Approximate Anticipated Approximate Approximate Area Estimated Area Average Excavation In-Place Volume Final Excavation Designation Volume (cubic (Square feet) Depth (cubic yards) yards) B 34,800 12 15,470 20,110 C 19,519 15 10,844 14,100 D 12,872 20 9,530 12,400 TOTAL 67,191 NA 35,844 46,610 �1 Therefore, Kleinfelder at this time estimates approximately 47,000 cubic yards of soil will need �] to be removed during remedial activities. 5.3 GROUNDWATER SAMPLING ANALYTICAL RESULTS Four groundwater samples were collected from the four deep pushprobe locations GI through G4. Three of these locations were located to assess expected downgradient and upgradient groundwater conditions at location G2, G3 and G4, respectively. One of these-probes (Gl) was advanced to assess groundwater condition beneath the oil impact footprint area northeast of the rupture point. The groundwater samples collected from one of the estimated upgradient locations (G4) and estimated downgradient location (G3) were non-detected for the requested petroleum constituents. Extractable hydrocarbons (TPH-D and TPH-O) and ethylbenzene were not detected in groundwater from any of the four groundwater samples collected. Relatively low concentrations of TPH-G was detected in groundwater samples collected from G1 at a concentration of 0.053 mg/l,just over the detection limit of 0.05 mg/l. Benzene was detected from GI at a concentration of 0.80 µg/1 and toluene was detected at 1.3 µg/1. Total xylenes were detected in the groundwater sample collected from Gl at a concentration of 1.69 µg/1. TPH-G was the only requested analyte detected in groundwater from the perimeter pushprobes, at location G2 (0.21 mg/1). The State and Federal Maximum Contaminant Level (MCL) for drinking water for benzene is 1 and 5 µg/1, respectively. The State and Federal MCL for toluene is 150 and 1,000 µg/1, respectively. The State and Federal MCL for xylenes is 1,750 and 10,000 µg/1, respectively. Based on the sampling results it appears trace levels of petroleum contaminants have migrated to groundwater at locations Gl and G2. However 4 of the 5 analytes detected were from Gl and within the footprint area. Since the concentrations are relatively low the potential exists that these values may have been generated from cross contamination from overlying petroleum impacted soil at this location. Additionally the nature of grab type samples are generally more suspect for cross contamination as compared to temporary or permanent monitoring wells that are properly developed and purged. oil 44843.703/ST04R1025 Page 12 of 16 Copyright 2004 Kleinfelder,Inc. August 6,2004 �l