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Petroleum/Solvents: Recommendations <br />While many soil reporting limits are not tabulated and two petroleum-related compounds were <br />detected in Hydropunch samples, these data do not indicate petroleum-related issues at OU 1. <br />TPHueh detected in initial Hydropunch samples does not exceed EPA Tap Water or Tier 1 <br />Groundwater ELSs, and neither TPHueh nor Bis(2-ethylhexyl)phthalate was detected in <br />subsequent samples collected immediately downgradient of initial detections, indicating that <br />groundwater concentrations were anomalous and spatially limited and therefore not indicative of <br />a larger plume. Moreover, soil data indicate there is likely no petroleum-related contamination at <br />OU 1. Most reporting limits have not been tabulated and can therefore not be analyzed against <br />Protection of Groundwater SSLs, but potential concentrations would be expected to be normally <br />distributed. Such a distribution resulting in no detections would have to fall well below reporting <br />limits. Kleinfelder therefore recommends spot-checking reporting limits to confirm they are <br />reasonably low and therefore constrain potential concentration distributions as expected. It is <br />anticipated that this exercise will provide the Board with data it needs to demonstrate due <br />diligence with respect to demonstrating that these data warrant no further action. <br />General Chemistry: Existing Data <br />Initial Phase II data do not include general chemistry analyses. <br />General Chemistry: Recommendations <br />The Regional Water Quality Board (Board) indicated it will want to review general chemistry data. <br />Specifically, the Board is interested in salts and nitrates. Kleinfelder therefore recommends <br />samples be collected and analyzed for carbonates, bicarbonates, and nitrates. Kleinfelder has <br />not encountered documents during review that provide details about the former septic system, so <br />Site-specific knowledge with which to anticipate results is not available. <br />OU 1 Work Plan <br />Spot <br />Check <br />Slide <br />Hammer <br />Passive <br />Soil Gas <br />Survey <br />Soil <br />Vapor Soil Hydropunch <br />Explorations <br />OU_BG-01 <br />through <br />OU_BG-05 <br />0U15-1 and OU1 5-2 <br />Samples 5 samples 6 samples 2 samples <br />Analyses CAM 17 <br />Metals <br />Carbonates, <br />Bicarbonates, <br />Nitrates <br />Carbonates, <br />Bicarbonates, <br />Nitrates, <br />potentially CAM <br />17 Metals <br />Kleinfelder will advance two pushprobe explorations (Figure OU1-1, samples OU1_5-1 and <br />OU1_5-2) in the vicinity of Phase II explorations 5-1 and 5-7. Soil samples will be collected at <br />depths of 5, 10, and 15 feet (below ground surface) bgs and analyzed for carbonates, <br />bicarbonates, and nitrates. A Hydropunch groundwater sample will also be collected from each <br />boring and analyzed for carbonates, bicarbonates, nitrates, and CAM 17 metals. Groundwater <br />20173951.001A/SAC17R68420 Page 4 of 26 <br />© 2017 Kleinfelder <br />November 2, 2017 <br />www.kleinfelder.com <br /> <br />KLEINFELDER 2882 Prospect Park Dr., Suite 200, Rancho Cordova, CA 95670 P1 916.366-1701 f I 916.366-7013