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0 DRAFT 0 <br /> 2) A total of four grab groundwater samples were collected, one in the footprint <br /> area and three from perimeter locations. Relatively low concentrations of <br /> petroleum constituents were detected in two of the four groundwater samples <br /> collected. The levels detected at the depths (first encountered groundwater) and <br /> locations in groundwater at the site were below state and federal Maximum <br /> Contaminant Levels (MCLs) for drinking water. The extent and distribution of <br /> hydrocarbons in groundwater is unknown at this time. Based on the relatively <br /> low levels detected, and since applicable petroleum constituents are below <br /> drinking water standards (MCLs), Kleinfelder at this time does not recommend <br /> clean-up or additional groundwater monitoring activities related to petroleum <br /> constituents detected in groundwater, <br /> 3) Kleinfelder anticipates that approximately 47,000 cubic yards of soil was <br /> impacted by petroleum constituents. Please note onsite stockpiles of petroleum <br /> impacted soil from Chevron's clean-up activities are not included in this estimate. <br /> Kleinfelder anticipates remedial excavation depths will range from 5 to 13 feet <br /> bgs. The estimated depths of petroleum impacted soil and anticipated future <br /> excavation depths are illustrated on attached Plates 3 and 4. <br /> A 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 /> 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 <br /> any groundwater contamination issues <br /> • If the clean up goal of non detect cannot be achieved a risk assessment from <br /> DTSC is 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 <br /> handling <br /> 44843.T04/ST05R997/DH:Iv Page 3 of 14 <br /> ©2005 Kleinfelder, Inc. August 16, 2005 <br />