FIELD DOCUMENTS - Laserfiche WebLink

Home Browse Search

' • �� KLEINFELDER ' affected soil from this excavation has leached to groundwater found at a depth of about 9 to 10 feet below ground surface (bgs). ' 6.1.2.3 COMPOSITE STOCKPILE SAMPLING ' Two four-point composite samples were collected form excavated soil form SE-B. The two samples were analyzed for a more comprehensive suite of analyses (See Section 5.1.2) based on landfill acceptance requirements and to assess potential contaminants. The additional analytes ' revealed relatively low concentrations of purgeable hydrocarbons (32 mg/kg) and a trace concentration of xylenes (11 µg/kg). TPH-D and TPH-O were detected at concentrations of 340 ' and 3900 mg/kg, respectively. Oil and Grease was detected at a high concentration of 6,280 mg/kg. Four of five LUFT metals were detected (Cr, Pb, Ni, and Zn), but at concentrations below the TTLC and STLC Regulated Level for classification of the metals as a hazardous waste ' per California Code of Regulations 22CCR §66261.24. Based upon the analytical results described above it appears that both purgeable and extractable petroleum type hydrocarbons were detected. Metal contamination of the 5 LUFT metals does not ' appear to have occurred based on the results of the two composite samples. It is Kleinfelder's opinion that the reported metal concentrations are likely reflective of naturally occurring ' background concentrations. The source of the petroleum hydrocarbon contamination and the source of the PCBs is unknown. 6.1.3 Large Excavation C (LE-C) ' 6.1.3.1 FIELD OBSERVATIONS ' Approximately 4,000 yards of soil was removed from LE-C. The excavation measured approximately 120 feet by 70 feet by 9 feet deep and is located in the vicinity of a former maintenance shop previously owned by R&B Trucking Company (See Plate 2). Discolored soil ' was noted at depths of about 2 to 9 feet bgs in most of the excavated soil. Field observations of the excavation showed that discolored soil was largely removed except along ' most of the northern sidewall were a large windrow prevented further excavation of soil. Based on two exploratory potholes advanced in the windrow north of the excavation, it appears that a band of contaminated soil approximately one foot thick was found about 20 feet north of the current northern excavation boundary. This band of discolored soil was noted at a depth of about 7 feet bgs. A second pothole (an additional 20 feet north) did not encounter discolored soils or petroleum odors. Therefore it appears that discolored and petroleum affected soil is diminishing towards the ' north and terminates between 20 to 40 feet north of the existing northern sidewall of LE-C. Soil from LE-C was excavated to an approximate depth of 9 feet where groundwater was encountered. No bottom samples were collected for this reason. It appeared that discolored soils continued in areas below groundwater, therefore groundwater sampling and analyses was also conducted (See discussion of groundwater findings in Section 6.2). No sheen or floating product ' 204341-1I.E01/201IR959 Page 25 of 31 Copyright 2001,Kleinfelder,Inc. August 21,2001