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DATA GAP ASSESSMENT WORK PLAN AND PATH TO CLOSURE REVIEW <br />Chase Chevrolet, 424 N. Van Buren Street <br />LTCP Closure Evaluation <br />January 2, 2018 <br />performance of a vapor intrusion investigation at the site. This data gap will be addressed in the <br />scope of work proposed below in Section 4.0 <br />3.2.3 Direct Contact and Outdoor Air Exposure <br />The available historical data set has a limited number of soil samples within the top ten feet of <br />the subsurface at the site that were submitted for laboratory analysis. During the January 2004 <br />site investigation performed prior to excavation activities at the site, soil samples were collected <br />from borings advanced surrounding the former UST pit (borings 16B-6b, 16B-7b, 16-B-8, and 16B- <br />9). These samples were reported with concentrations of benzene and ethylbenzene below the <br />most stringent LTCP residential screening levels for direct contact and outdoor air exposure; the <br />presence of naphthalene in these samples was not evaluated. These samples, collected in the <br />immediate vicinity of the former UST pit (16B-6b, 16B-7b, and 16B-8) and in the downgradient <br />direction to the north-northeast (16B-9) indicate that residual petroleum hydrocarbon mass is not <br />present in shallow depths of up to 10 feet bgs. This distribution model is supported by the nature <br />of the site configuration at,the time of the release, with one UST that did not have a network of <br />near surface conduits for the retail petroleum fuel dispensing. <br />While this is not a data gap at the site, it would be prudent to analyze soil samples from shallow <br />soil depths (0-10 feet bgs) for the presence of benzene, ethylbenzene, and naphthalene during <br />additional data gap assessment activities proposed below in Section 4.0. <br />Stantec <br />arn \\us1312- <br />f02\workaroup\ 1857 \ active\ 185703766 \ 05_report_deliv \ deliverable \ work_plan \185703766_20180102_424_van_buren_work_plan_final.docx 3.4