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Pmpamf far Crmdafring Se"icm MACTEC Propowl Nn.05-RA1.-0302 <br /> Awcricrra Mmrlding amd Millwork Aagusr 37,200.5 <br /> Sux*ee n,Qrlifamia Page 2 <br /> Pentachlorophenol Areas <br /> • Install three soil borings to approximatelyU feet below ground surface(b n the truck parking alert <br /> and laboratory testing of three soil samples for phenols using test methods referenced in the <br /> Workplan <br /> • Install one soil boring to approximatel 10 Feet b . in the truck parking area and laboratory testing of <br /> one soil sample for phenols. <br /> Underground Stora of Tanks <br /> • Install a total of IS soil borings to depths between10 and 20 b at UST locations 18820001/18822, <br /> -0003,4(104,-0006,-0007,47008, -0009,-0011,-0012,-0013 and 014,and laboratory testing of soil <br /> samples for only those COC associated with previous contents of the respective tanks. Sampling <br /> protocols and laboratory test methods outlined in the Workplan will be utilized for this additional <br /> work. <br /> • Install a total of five soil-gas sampling probes in the UST 188200021-0005 grown ater-contaminant <br /> plume area, and colFi:cuon of depth-discrete soil-gas samples from depths of and I5 feet for <br /> laboratory testing for VOCs- using modified EPA Method TO-15 utilizing sampling protocols <br /> previously referenced in the Workplan. <br /> Septic Tanks <br /> On the basis of MACTEC's previous review of laboratory data collected by Advanced <br /> OeoLnvironmental, Inc. in their 2000 and 2001 field investigations, it appears that this laboratory data <br /> meets QA/QC and data-quality objectives necessary to conduct the risk assessment. Therefore, we are <br /> not recommending further assessment at the previously investigated septic tank locations. Although we <br /> do not have documentation of sampling at the three remaining septic tanks(east of the Cover Plant, south <br /> Of the former Nurse's Station, and west of the former Maintenance Building), MACTEC does not have <br /> evidence to support the meed for further assessment because we do not have knowledge that hazardous <br /> materials were discharged to their; tanks. MACTEC will utilize the risk assessment conclusions derived <br /> from the investigated septic-tank locations to evaluate these locations. DTSC stipulated at the February <br /> 9,2005 briefing on site status that further investigation was not needed for these areas. <br /> Transformers <br /> • Collect two wipe samples obtained from the concrete after removal of the four transformers at the <br /> Millwork Building,and testing of the wipes in the laboratory for PCBs utilizing EPA Method 8082. <br /> • Take pictures of the transformers and their test labels, and collect and present information <br /> documenting disposal of current and previously-used transformers at a licensed facility. <br /> Background Sampling <br /> • Collect six shallow soil sam les,one each at six locations, and test the samples forTitie 22 metals to <br /> establish bac r`oun metals concentrations in the vicinity of the site. Depending on the test results <br /> and the correlation among the samples, it may be necessary to collect and analyze additional soil <br /> samples to establish representative background concentrations. This decision will be made after the <br /> analysis results are known and a preliminary assessment of the data has been conducted. <br /> ,4MACTEC <br />