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ameo <br /> Memo <br /> To: Mike Infurna, SJCEHD Project: 6628.001 <br /> From: Mari Gilmore cc: <br /> Tel: (510) 663-4163 <br /> Fax: (510) 663-4141 <br /> 5 <br /> Date: April 24, 2009 0 e 5-7Z37 <br /> Subject: Workplan for 990 Beechnut, Tracy, CA, May 2009 <br /> AMEC Geomatrix is proposing to conduct pre-excavation investigation work at the 990 W. Beechnut Ave <br /> site in Tracy, CA. The work will consist of a series of hand-augered borings on approximately 15-foot <br /> centers outlining the currently proposed excavation limits (approximately 15 borings). See Figure <br /> attached. This excavation is being conducted to remove a limited amount of soil from the site that has <br /> elevated polycyclic aromatic hydrocarbon (PAH) impacts based on a Screening Level Risk Assessment <br /> that was performed (Geomatrix, 2008). <br /> Borings will be advanced to approximately 6 feet below ground surface, or to the total depth of the <br /> observed impacted soil. If impacted soil is observed in a boring, a step-out boring will be advanced 10 <br /> feet laterally from the impacted boring. If soil in a step-out boring appears unimpacted, a soil sample will <br /> be collected at the depth of the observed impacts in the nearby borings to define the "clean" boundary. <br /> Soil samples will be analyzed for PAHs only, as they are the risk drivers for the site. If no impacted soil is <br /> observed in an original boring, a "step-in" boring will be advanced 10 feet laterally into the proposed <br /> excavation limits and step-in borings will be advanced as above until the "clean" boundary is identified <br /> based on visual indications. <br /> This workplan was proposed to the California Regional Water Quality Control Board, Central Valley <br /> Region, and approved by the regulator, Dean Hubbard, in an email dated April 1, 2009 (see attached). <br /> Please let me know if you have any questions. <br /> Sincerely yours, <br /> AMEC eomatrix, Inc. <br /> Mari Gilmore <br /> Project Geologist <br /> E-mail: mari.gilmore@amec.com <br /> MMG <br /> is\project\6000s\6628.001\5000 investigation\memo.doc <br /> Attachments— Figure 1 <br /> 4/1/09 Email from Dean Hubbard, Central Valley Water Board <br /> AMEC Geomatrix, Inc. <br /> 2101 Webster Street, 12th Floor <br /> Oakland,California <br /> USA 94612-3066 <br /> Tel (510)663-4100 <br /> Fax (510)663-4141 AMEC Geomatrix ,: <br /> www.amecgeomatrixinc.com <br />