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�` ■ KLEINFELDER 6.1.2 Small Excavation B (SE-A) ' 6.1.2.1 FIELD OBSERVATIONS ' Approximately 75 yards of soil was removed from SE-B. This excavation measured approximately 14 feet by 28 feet by 5 feet deep and was located on proposed residential Lot 23 ' near the western border of the subject site. Field observations of the excavation showed that discolored soil was largely removed except along a 10-foot section of sidewall located near the northwest portion of the excavation. Additional soil could not be excavated in this area due to ' proximity of a boundary fence ' 6.1.2.2 CONFIRMATION SAMPLING Six confirmation soil samples were collected from within the excavation. Each of the six ' confirmation samples collected within the excavation were analyzed for TPH-D and TPH-O. One of the six confirmation soil samples was also analyzed for PCBs. The two four-point composite soil samples collected from the excavated material from SE-B were analyzed for the following: ' TPH-D, TPH-O, Oil and Grease, Volatile Organics, Semi-Volatile Organics, TPH-P, BTEX and LUFT 5 metals (Cd, Cr,Pb,Ni and Zn). ' Three of six confirmation samples had detections of extractable hydrocarbons. The highest concentration of TPH-O and TPH-D found at 2,100 and 170 mg/kg, respectively was taken from ' a sample collected in discolored soil in the 10 foot section of sidewall noted above. A PCB compound, Aroclor 1260, was detected at a concentration of 34 µg/kg from this same soil sample. A bottom sample also had TPH-O and TPH-D detected at 46 and 6.5 mg/kg. A trace ' concentration of TPH-D of 1.6 mg/kg was detected in a western sidewall sample, collected just south of discolored section of soil. The concentration of 34 µg/kg for Aroclor 1260 (PCB Compound) detected in soil was found to be below the PRG for residential use for this compound,which is 220 µg/kg. This concentration of 34 µg/kg was also well below the Total Threshold Limit Concentration (TTLC) Regulated ' Level for classification of total PCBs as a hazardous waste per California Code of Regulations 22CCR §66261.24. Additionally these concentrations were not greater than 10-times the Soluble Threshold Limit Concentration (STLC) Regulated Level for PCBs as expressed in 22CCR ' §66261.24. The factor of 10-times the STLC Regulated Level is commonly used as an indicator as to whether or not a STLC analysis is appropriate to be ran on the sample ' Based on these results and field observations it appears that most of the petroleum affected soil has been removed except along the '10 foot section of discolored soils near the northwest portion of the sidewall. The bottom sample did have concentrations of diesel and oil hydrocarbons as ' noted above. However in Kleinfelder's experience these concentrations would generally not trigger additional action or mitigation from local and state regulatory agencies. Based on groundwater sampling results discussed later in this section is does not appear that petroleum ' 20.4341-11.1301/20118959 Page 24 of 31 Copyright 2001,Kleinfelder,Inc. August 21,2001