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07 December 2020 <br />Project No. 20-6249 <br />Page 2 of 6 <br />hydrocarbon impact to soil and groundwater in the location of the former UST. No <br />additional investigation was performed at the time. <br /> <br />In September 2015, AGI completed a Phase I environmental assessment of the subject <br />property. The following recognized environmental condition (REC) was identified: <br /> A vapor intrusion condition (VEC) exists at the site as a result of the historical UST <br />containing xylenes on the property. <br /> <br />Based upon the REC, AGI advanced three (3) soil borings (V1 through V3) to depths of <br />10 feet below surface grade (bsg) for collection of soil-vapor samples in October 2015. <br />Benzene, toluene, ethylbenzene, total xylenes (BTEX), and several other volatile organic <br />compounds (VOCs) were detected in the soil-vapor samples. At the time, only one VOC <br />concentration (benzene) exceeded the established environmental screening levels <br />(ESLs). AGI concluded there was minimal risk and a low threat for intrusion of VOC- <br />impacted soil-vapor to indoor air. <br /> <br />Since October 2015, the ESLs for indoor air, and subsequently soil-vapor, have <br />significantly decreased and become more conservative. While at the same time, soil- <br />vapor sampling and collection procedures have been perfected. Due to the changes in <br />ESLs and sampling techniques, AGI recommends collecting soil-vapor samples near the <br />locations of V1 and V3 to establish current soil-vapor concentrations and to evaluate the <br />potential threat for vapor intrusion into the site building (Figure 2). <br /> <br />Additionally, since soil and groundwater samples were not analyzed during the 2000 <br />investigation, AGI recommends analyzing soil and groundwater samples from four <br />locations on the property to assess the current conditions in the former UST area and to <br />verify that dissolved impact has not migrated onto the property from an offsite source. <br /> <br /> <br />2.0. SCOPE OF WORK AND PROCEDURES <br /> <br />AGI proposes to advance a total of six (6) soil borings at the site. Four (4) borings will be <br />advanced to total depths of 20 feet bsg for collection of soil and groundwater samples <br />and two (2) borings will be advanced to 5 feet bsg for collection of soil-vapor samples. <br />Borings will be advanced along the northern and western property boundaries, in the <br />former UST area, and downgradient of the former UST area. Proposed soil boring <br />locations are depicted in Figure 2. <br /> <br />The proposed scope of work includes the following tasks: <br /> <br /> Permitting and pre-field work activities. <br /> Soil boring advancement and sample collection. <br /> Soil-vapor point installation, sampling, and analysis