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kTJ KLEINFELDER 6 CONCLUSIONS AND RECOMMENDATIONS Kleinfelder conducted a limited soil and groundwater assessment to assess the lateral and vertical limits of potential petroleum impacted soil at the petroleum pipeline spill area (subject site). Kleinfelder collected much of the data in 4-point composite soil samples for the anticipated profile- process for disposal purposes (Class II Landfill). Please note however acceptance criteria may include additional sampling and analyses depending upon the specific landfill and gate acceptance criteria, therefore, additional analysis may be needed. Kleinfelder has preliminarily noted that the highest concentration of constituents detected in composite samples may exceed gate acceptance criteria at a Class H Landfill/s. If concentrations limits are not acceptable to local Class H Landfill/s, excavation activities may need to involve onsite stockpiling and additional sampling and analyses for additional detailed profiling of the petroleum impacted soil. Potential disposal at a Class I Landfill will markedly increase transportation and disposal costs. Additional details regarding these items will be addressed under separate cover in a workplan to be submitted to SJC/EHD. The following conclusions and recommendations were developed based on the data and information obtained from Kleinfelder's Limited Soil and Groundwater Assessment 1) Based on field indications (PID reading, discolored soil and odors etc.) and analytical results significant petroleum impacted soil was noted primarily north and east of the Chevron crude oil pipeline at depths ranging from 5 to 12 feet bgs (See Plate 3). A portion of significant petroleum impacted soil was also noted west and immediately south of the rupture area (south of the Chevron pipeline) at depths estimated at 5 to 8 feet bgs. The southern-most portion of the footprint area, with an estimated area of 27,000 square feet did not appear to be impacted by petroleum constituents. These estimates do not include a significant underlying leaching(transition zone)noted prior to encountering"clean" soil. 2) Kleinfelder estimates an in-place volume of 17,710 cubic yards of obvious petroleum impacted soil and an estimated excavated volume of 23,440 cubic yards. Including the transition zone Kleinfelder anticipates remedial excavation depths will range from 12 to 20 feet bgs and volumes to approximately double. For anticipated clean up excavation activities (including the transitions zone) Kleinfelder estimates an in-place volume of 35,844 cubic yards and an estimated final excavation volume of 47,000 cubic yards. Please note onsite stockpiles of petroleum impacted soil from Chevrons clean-up activities are not included in this estimate. 3) Nine discrete soil samples were collected and analyzed primarily to assess the vertical limits of petroleum impacted soil. These nine discrete soil samples were collected from the approximately total depths of pushprobes PP2, PP6, PP10, PPI 1, PP17, PPI 8, PP19, PP21 and PP25, located mostly in obviously petroleum impacted areas. Sampling depths ranged from 7 to 24 feet. Eight of these nine soil samples were non-detected for the requested petroleum constituents. One of the nine soil samples collected from PP19 at a depth of 19 feet had a reported TPH-D concentration of 9.5 mg/kg. Based on the discrete soil sampling results of these nine samples it appears the vertical migration of petroleum constituents is 44843.T03/ST04RIO25 Page 13 of 16 Copyright 2004 Kleinfelder,Inc. August 6,2004