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Mr. Alan M. Buehler
<br /> May 19, 2017
<br /> o The soil sample collected at 6 feet bgs from B-55 will also be analyzed for PAI-Is by
<br /> USEPA Method 8260B
<br /> Soil samples collected from boring B-57 (6 feet and 13 feet bgs)will be analyzed for the following
<br /> constituents:
<br /> • Title 22 metals by USEPA Method 8260B
<br /> As mentioned in Section 4.2.3 of the CSM, although no naphthalene soil data are available, as suggested
<br /> in the technical support document to the LTC Policy (SWRCB 2011), the LTC Policy exclusion criteria
<br /> derived for benzene are assumed to be conservative for naphthalene, which is relatively less volatile than
<br /> benzene (i.e., has a much lower solubility value and Henry's Law coefficient than benzene) and similarly
<br /> susceptible to biodegradation.
<br /> Investigative Derived Waste Transport and Disposal
<br /> Investigative derived waste (IDW) generated during drilling operations will be containerized in 55-gallon
<br /> drums and temporarily stored onsite pending characterization for offsite disposal. A composite sample of
<br /> the IDW will be collected for waste profiling purposes, if necessary. Following receipt of waste
<br /> characterization sampling results, the IDW will be transported to an appropriate disposal facility.
<br /> Dry Well Evaluation
<br /> An evaluation of dry wells and summary of most recent available groundwater data are presented in
<br /> Table 1 and shown on Figures 3 and 4. Current and historical groundwater analytical data are
<br /> summarized on Tables 2 and 3, and well construction details are summarized on Table 4.
<br /> Shallow Zone Wells
<br /> Groundwater samples were collected from seven of the 27 shallow zone wells (including vapor extraction
<br /> wells) during the first quarter 2017 (MW-2, MW-8, VW-2, VS-3, VW-5, VW-6, and VW-10). Seven of the
<br /> 27 shallow wells have often been dry since they were installed (MW-4, MW-6, MW-13, VW-1, VW-4,
<br /> VW-14, and VW-19). Ten shallow zone wells have been dry since they were installed, and groundwater
<br /> samples have not been collected from these wells (MW-14, VW-7, VW-8, VW-9, VW-11, VW-12, VW-13,
<br /> VW-16, VW-18, and VW-20).
<br /> Deep Zone Wells
<br /> Groundwater samples were collected from nine of the 21 deep zone wells (including air sparge wells)
<br /> during the first quarter 2017 (MW-1, MW-10, MW-12, MW-16, MW-17, MW-18, MW-20, AS-313, and
<br /> AS-6). Three of the 21 deep wells have often been dry since they were installed (MW-5, MW-9, and
<br /> M"Ll5). Three deep zone wells have been dry since they were installed, and groundwater samples have
<br /> not been collected from these wells (MW-3, MW-7, and MW-19). Groundwater samples were collected
<br /> from three air sparge wells during the third quarter of 2016 (AS-1, AS-4, and AS-5); these wells were not
<br /> accessible for sampling in first quarter 2017. Additionally, groundwater samples have not been collected
<br /> from air sparge wells AS-2, AS-7, and AS-8; however these wells were not sampled due to inaccessibility,
<br /> not due to insufficient water.
<br /> arcadis.com Page:
<br /> CA 06100 170519 SP Revised Work Plan docx 4/6
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