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' KLEINFELDER <br /> A summary of Kleinfelder's findings are summarized as follows: <br /> ' 1) Twelve discrete soil samples were collected and analyzed from perimeter pushprobe <br /> borings at depths ranging from 5 to 43 feet bgs. Based on this data, it is Kleinfelder's <br /> opinion that petroleum impacted soil has not migrated laterally a significant distance <br /> ' beyond the footprint area. Please note this finding does not include potential soil vapor <br /> migration of volatile compounds, since soil vapor sampling was not conducted as part of <br /> this assessment. <br /> t 2) A total of four grab groundwater samples were collected, one in the footprint area and <br /> three from perimeter locations. Relatively low concentrations of petroleum constituents <br /> were detected in two of the four groundwater samples collected. The levels detected at <br /> ' the depths (first encountered groundwater) and locations in groundwater at the site were <br /> below state and federal Maximum Contaminant Levels (MCLS) for drinking water. The <br /> extent and distribution of hydrocarbons in groundwater is unknown at this time. Based on <br /> the relatively low levels detected, and since applicable petroleum constituents are below <br /> ' drinking water standards (MCLs), Kleinfelder at this time does not recommend clean-up <br /> or additional groundwater monitoring activities related to petroleum constituents detected <br /> in groundwater, <br /> ' 3) Kleinfelder anticipates that approximately 47,000 cubic yards of soil was impacted by <br /> petroleum constituents. Please note, onsite stockpiles of petroleum impacted soil from <br /> Chevron's clean-up activities are not included in this estimate. Kleinfelder anticipates <br /> remedial excavation depths will range from 5 to 13 feet bgs. The estimated depths of <br /> petroleum impacted soil and anticipated future excavation depths are illustrated on <br /> attached Plates 3 and 4. <br /> IA Revised Workplan was submitted to EHD titled "Revised Workplan/Scope of Work, <br /> Soil Excavation Observation, Sampling and Analyses, Petroleum Pipeline Spill, 23577 <br /> ' Mountain House Parkway, Mountain House, California", dated September 2, 2004. The <br /> workplan detailed excavation of petroleum impacted soil and confirmation soil sampling. <br /> The workplan did not address specifics of removal around the Chevron Pipeline and <br /> 1 PG&E pipelines. <br /> EHD responded to the workplan in a letter titled "23577 Mountain House Parkway, <br /> Mountain House, California", and dated September 23, 2004. EHD in summary stated <br /> the following: <br /> Regional Water Quality Control Board (RWQCB) should be contacted to assess any <br /> groundwater contamination issues; <br /> If the clean up goal of non detect cannot be achieved a risk assessment from DTSC is <br /> recommended. <br /> • Address soil removal and health and safety issues near pipelines. <br /> Address backfill and compaction and source of material. <br /> • Address the existing onsite contaminated soil stockpiles and final disposition. <br /> • Provide documentation regarding the disposal arrangement. <br /> • Provide subcontractor information and certification of hazardous waste/material handling. <br /> 44843.T04/STO5R1333/DH:Iv Page 3 of 17 <br /> 0 2005 Kleinfelder, Inc. October 25,2005 <br />