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Phase II Environmental Site Assessment Report Yosemite Senior Housing 309 W.Yosemite Avenue and 105 Sycamore Avenue APNs 217-210-100 and 217-210-110 Page 6 respective laboratory reporting limits in groundwater is unlikely to pose a risk to human health of the future occupants. The Site-specific CSM is included in Appendix F. Laboratory analytical results and the human health screening levels for the groundwater samples are included on Table C,Appendix E. 5.0 CONCLUSIONS The Site comprises approximately 0.223 acres designated as APNs 217-210-100 and 217-210-110, located at 309 W. Yosemite Avenue and 105 Sycamore Avenue in Manteca, San Joaquin County, California. According to the Phase I ESA prepared by Condor,based on review of historical documents, the western Site parcel was used as a printing shop from the 1900s until the early 1960s,when the building was replaced with the asphalt driveway and lot. The eastern Site parcel was used as a hotel and apartment from the late 1910s until the 1990s, when the building was replaced with asphalt driveways and parking lot. Condor identified one former fuel station and boiler room on the southern adjoining property (across Yosemite Avenue approximately 75 feet south)from at least the 1920s to 1940s.No documents were found pertaining to the southern adjoining property's oil and gas station or boiler room. Condor also identified a total of one former underground storage tank(UST) location and a dry-cleaning operation located approximately 550 feet west-southwest of the Site. Previous investigations related to a historical fuel release from the UST location at 420 West Yosemite Avenue identified the presence of PCE in groundwater at a maximum detected concentration of 2,160 µg/L. Because the former UST location has no historical documented use of PCE,the Central Valley Regional Water Quality Control Board identified the French Cleaners location as a potential source. Condor recommended a Phase II ESA be performed to continue the due diligence process. A total of six(6) soil gas samples,three(3) soil samples, and two(2)groundwater samples were collected. Soil gas samples were analyzed for VOCs by TO-15, and soil and groundwater samples were analyzed for VOCs by EPA Method 8260B. Concentrations of VOCs in soil were compared to the most recent USEPA RSLs or DTSC-SLs, concentrations of VOCs in groundwater were compared to SF-ESLs, and concentrations of VOCs in soil gas were compared with attenuated(attenuation factor of 0.03) DTSC-SL or USEPA RSLs indoor air screening levels. None of the VOCs in soil gas detected above their respective reporting limits exceeded their respective attenuated indoor air screening levels, except for PCE in three (3) of the collected samples and in two locations. PCE was detected in all collected samples. PCE was detected at 45 µg/m3 at ASG-1-5.5; 6.5 µg/m3 at ASG-1-15; 6.5 µg/m3 at ASG-2-5.5; 11 µg/m3 at ASG-2-15; 41 µg/m3 at ASG-3-5.5; and 16 µg/m3 at ASG-3-15. The DTSC-SL for indoor air for PCE with the applied default 0.03 attenuation factor is 15.3 µg/m3. 1,1 DFA was detected at low to moderate concentrations in all of the collected soil gas samples. The presence of the tracer gas suggests that the sample may have been diluted; therefore, PCE concentrations may be higher than what was reported. VOCs were not detected at or above their respective reporting limits in the collected soil samples.Reporting limits were sufficient for comparing to the USEPA RSLs or the DTSC-SLs for residential soil in most instances.VOCs were not detected at or above their respective reporting limits in the collected groundwater samples. While not all reporting limits were sufficient for comparing concentrations to the SF-ESLs for groundwater,the exposure pathway for the COCs is by inhalation;therefore,the potential presence of COCs at concentrations below the respective laboratory reporting limits in groundwater is unlikely to pose a risk to human health of the future occupants. ILA CONDOR