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29 January 2024 AdvancedGec Project No. 23-7523 An Employee-Owned Company Page 7of8 n � • Constituents of concern were not detected in any of the soil samples collected during the October/November 2023 or the January 2024 investigation. Based on the data collected, the subsurface of the site is impacted primarily by chlorinated hydrocarbons in the soil-vapor phase only. • The site lithology is generally composed of silty sand and sandy silt mixtures from near surface grade to 35 feet bsg. • PCE detections in all soil-vapor samples collected during this investigation exceeded the ESL of 67 pg/m3 for a commercial/industrial setting in five of the ten samples. The maximum concentrations were detected in the rear of the 308 North Ham Lane suite at a depth of 30 feet below surface grade. However, based on the reported concentrations, PCE concentrations in soil-vapor samples appear to generally attenuate across the site with the exception of the samples collected at V6with depth (Figures 2 through 6; Table 2). • PCE impact in soil-vapor generally decreases in concentration laterally away from the rear of the 308A suite, which appears to be the source area of the soil-vapor impact (Table 2; Figures 2 through 5). • In general, the additional VOCs detected in the soil-vapor samples were below their respective ESLs, with the exception of benzene. Benzene detections are more likely the result of historical releases at the adjacent fueling facility to the south of the subject property (Table 2). • Chlorinated hydrocarbon detections in indoor air samples were generally below commercial ESLs, with the exception of the sample collected within the former Boost Mobile suite. Furthermore, TCE was not detected in any of the indoor air samples (Table 3). 5.0. RECOMMENDATIONS Based on the findings of this investigation, AGI recommends preparation of a soil-vapor extraction pilot test work to evaluate mitigation of residual soil-vapor impact. 6.0. LIMITATIONS Our professional services were performed using that degree of care and skill ordinarily exercised by environmental consultants practicing in this or similar localities. The findings were based upon field measurements and analytical results provided by an independent laboratory. Evaluations of the hydrogeologic conditions at the site for the purpose of this investigation are made from a limited number of available data points (i.e. field data, soil samples, and soil-vapor samples) and subsurface conditions may vary away from these data points. No other warranty, expressed or implied, is made as to the professional interpretations, opinions and recommendations contained in this report.