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21 December 2017 <br />AGE-Project No. 14-3154 <br />Page 6 of 23 <br /> <br />samples were significantly below the established RSL for industrial soil of <br />0.000022 mg/kg or 22 ppt. No other chemicals of concern were detected in the six <br />soil samples (Table 5). <br /> Subsurface Boring Investigation – July 2015: Between 29 and 31 July 2015, soil <br />borings AB26, AB27, AB28 were advanced within the former waste/glass handling <br />area (AB26) and on the eastern and northern boundaries of the waste handling <br />area (AB27 and AB28) to further evaluate the potential impacts from the <br />management of glass waste (Figure 3; Tables 1 -3). Groundwater samples were <br />collected from shallow monitoring wells W-0, W-1R, W-2. Wells W-0 and W-1R <br />were located in the North Waste Cell and along the southern property boundary of <br />the site, respectively. Well W-2 is located along the northern property boundary of <br />the site. Native soil was encountered in all the borings from surface grade to 15 <br />feet bsg, no glass waste was observed (Appendix A). Selected soil and <br />groundwater samples from all three borings were analyzed for CAM 17 metals, <br />VOCs (only AB26-W), PCBs, PNA, PAH or SVOCs, dioxin and furan and TPH. <br />TPH, VOCs, SVOCs and PCBs were not detected in the samples analyzed for <br />those constituents. Various metals were detected in the soil samples at <br />concentrations below the DTSC-SLs and RSLs or at levels consistent with <br />background concentrations in California soils (Tables 1 – 6). <br />Dioxin and furans were reported in two of the soil samples (AB26-5 and AB27-5). <br />One dioxin [Octachlorodibenzo-p-dioxin (OCDD)] was detected at a TEQ of <br />0.00526 ppt in AB26-5 and 0.0071 ppt in AB27-5. Though, the regulated dioxin <br />compound 2,3,7,8-TCDF was not detected. Also, one groundwater sample (AB26- <br />W) collected within the former waste/glass handling area had detections of dioxin <br />and furan (TEQ 0.141 ppt). Again, it was the unregulated OCDD that was detected <br />and not the regulated compound 2,3,7,8-TCDF which has a drinking water quality <br />standard MCL of 14.1 ppt. The two other grab groundwater samples (AB27-W and <br />AB28-W) collected within the former waste/glass handling area did not have <br />detections. Additionally, dioxin and furans were not detected above the reporting <br />limits in the groundwater samples collected from wells W-0, W-1R and W-2 <br />(Tables 5 and 6). <br /> Soil-Gas Investigation – July and August 2015: On 29 July 2015, soil-gas probe <br />VP-1 was installed in the waste/glass handling area at the direction of the LEA. <br />The soil-gas probe design is depicted in Figure 5. On 10 August 2015, two soil- <br />gas samples were collected under the inspection of the LEA (initial sample and <br />replicate); and in April 2017, an additional soil-gas sample was collected to verify <br />previous results. AGE followed the soil-gas sampling procedures outlined in the <br />Soil Vapor Investigation Work Plan Addendum - June 2015, dated 15 June 2015. <br />Based on the soil gas sampling results from August 2015, methane concentrations <br />within the waste area were detected at 4,800 microliters per liter (µL/L) or 0.48%; <br />and oxygen levels were detected between 15,000 µL/L and 17,000 µL/L or 1.5% <br />to 1.7%. Analytical data collected from the soil-gas probe in April 2017 did not <br />detect methane above the laboratory reporting limit of 2.0 µL/L, and oxygen was