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�� KLEINFELDER <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. Excavation in <br /> and around the Chevron and PG&E pipelines are discussed separately within this <br /> workplan. Based on this workplan, it is estimated that residual petroleum impacted soil <br /> will remain at beginning depths ranging from 5 to 13 feet to approximately 25 feet in some <br /> areas. Residual petroleum impacted soil will also likely remain directly beneath PG&E <br /> ' Line 401 and potentially in proximity to PG&E Line No. 2 and Chevron's pipeline as <br /> limited by geotechnical and safety considerations. <br /> Existing soil piles generated during Chevron's emergency response activities are also <br /> proposed to be removed and disposed of at an appropriate landfill. Waste manifests and <br /> subcontractor information will be provided as part of the remedial activities. At this time, <br /> ' Kleinfelder understands Pacific States Environmental Contractors of Dublin California, a <br /> hazardous waste contractor and subsidiary of De Silva Gates will be the general <br /> contractor for excavation of impacted soil at the site and arrangement of offsite <br /> ' transportation and disposal. Pacific States is not a Kleinfelder subcontractor and is <br /> contracted with Pegasus MH Ventures I. <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 /> 44843.T04/STO5R1333/DH:ly Page 4 of 17 <br /> 0 2005 Kleinfelder, Inc. October 25,2005 <br />