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22 November 2023 AdvancedGeo Project No. 23-7523 An Employee Owned Company Page 6 of 7 � • PCE detections in all soil-vapor samples collected during the investigation exceed the commercial ESL of 67 pg/m3 for a commercial/industrial setting. The maximum concentrations were detected in the rear of the 308 North Ham Lane suite as well outside to the east of the suite (Figures 2 through 5). • PCE-impacted soil vapor generally appears to decrease with depth in all locations, except V6 where an increase was observed (Table 2, Figures 2 through 5). • PCE impact in soil-vapor remains undefined laterally in all directions and vertically at depths greater than 15 feet bsg (Table 2; Figures 2 through 5). • TCE concentrations detected in two of the soil-vapor samples exceed thresholds that generally require immediate indoor air sampling. Indoor air samples collected during the Partner investigation in July 2023 only detected PCE at low concentrations but did not analyze for TCE. Therefore, additional investigation of indoor air is warranted at this time. • 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). 5.0. RECOMMENDATIONS Based on the findings of this investigation, AGI recommends the following: • Further investigation and assessment to define the lateral and vertical extent of the VOC-impacted soil-vapor. During the next phase of assessment, vapor extraction wells should be considered for performance of a soil-vapor extraction pilot test to mitigate impact detected during the investigations. • TCE was detected during this investigation at concentrations that trigger immediate indoor air sampling. Because Partner did not analyze TCE in their indoor air samples, additional indoor samples are recommended. 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.