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• DRAFT 0 <br /> PURPOSE OF WORKPLAN <br /> The following scope of work was developed to address several of the issues noted by <br /> EHD as listed above and to present additional phases of work based on further <br /> evaluation of site limitations and clean-up options. The modifications and additional <br /> work were found necessary due largely to safety considerations related to the Chevron <br /> and PG&E pipelines. The safety issues will require leaving some petroleum-impacted <br /> soil in-place at the site. As a result, this workplan proposes a modified excavation plan, <br /> a follow-up human health screening evaluation and a groundwater monitoring program <br /> to address the residual soil left in place. The human health screening evaluation is <br /> proposed to evaluate risk to workers based on a industrial/commercial site use. The <br /> monitoring wells are proposed to monitor potential impact to groundwater from the <br /> residual petroleum impacted soil left in place. <br /> SCOPE OF WORK <br /> This workplan details the scope of work for groundwater monitoring well installation, soil <br /> excavation observation, confirmation sampling and analysis, and human health risk <br /> evaluation at 23577 Mountain House Parkway in Mountain House, California (Plate 1). <br /> TASK 1 — EXCAVATION OBSERVATION AND SOIL SAMPLING COLLECTION <br /> Kleinfelder proposes excavation of obviously impacted soil at depths ranging from 5 to 13 <br /> feet below ground surface (bgs) as approximately illustrated on Plate 4 not including the <br /> Chevron and PG&E Pipeline easement areas. Based on this workplan it is estimated that <br /> residual petroleum impacted soil will remain at beginning depths ranging from 5 to 13 feet <br /> to approximately 25 feet in some areas. Residual petroleum impacted soil will also <br /> remain in close proximity to the Chevron and PG&E Pipelines. <br /> Kleinfelder personnel will be present to observe excavation activities, document soil <br /> conditions and to collect confirmation soil samples. At this time Kleinfelder is not <br /> proposing excavation in Area A (See Plate 3), since field observations and analytical <br /> results in this area from Kleinfelder's previous pushprobe assessment does not appear to <br /> warrant remedial activities. <br /> Chevron Pipeline Easement Area <br /> It is Kleinfelder's understanding that approximately 300 feet of the Chevron Crude Oil <br /> Pipeline will be removed and replaced by Chevron. The Chevron Pipeline at this time is <br /> mostly exposed in the spill area and two PG&E natural gas pipelines trend parallel and <br /> within approximately 5 and 30 feet north of the Chevron Pipeline. The removal and <br /> replacement of the Chevron Pipeline presents a one-time opportunity to remove soil <br /> beneath the Chevron Pipeline. Kleinfelder proposes coordination of removal of soil <br /> beneath the Chevron Pipeline immediately after removal of the Pipeline by Chevron. <br /> Both Chevron and PG&E will be forwarded this workplan and will be contacted to be <br /> present for coordination of field activities. It is expected that California Gas Transfer <br /> 44843.T04/ST05R997/DH:Iv Page 4 of 14 <br /> ©2005 Kleinfelder, Inc. August 16, 2005 <br />