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Each SUMMA canister valve was opened, which caused air to enter the canister due to the pressure differential. Partner remained on-site for the duration of sampling and checked the canister vacuum pressures each hour.The canister valves were closed after approximately 8 hours, with pertinent data (e.g., time and canister vacuum) recorded at the start and end of the sampling event. The SUMMA canisters were labeled for identification and stored away from direct sunlight prior to analysis. Refer to Appendix D for the field sampling data sheets. 3.5 Soil Sampling Borings 131 and B2 were overlain by asphalt, which was penetrated using a punch bit attachment advanced by the direct-push drill rig. Borings B3 and B4 were overlain by concrete, which was penetrated using a hand-held rotary hammer with a 3-inch diameter core barrel. Borings 131 through B4 were advanced to terminal depths of 40, 50, 16, and 16 feet bgs, respectively. Soil samples were collected using a 4-foot long by 2.25-inch diameter MacroCore sampler with a 4-foot long acetate liner, which was advanced by the direct-push drill rig using 4-foot long by 1.5-inch diameter drill rods.The sampler was driven into the subsurface to allow undisturbed soil to enter the open MacroCore barrel and retrieved in 4-foot intervals to recover the soil-filled liners. A lengthwise section of each acetate liner was removed with a splitting tool to expose the soil. The soil column was visually inspected for discoloration, monitored for odors, and classified in accordance with the Unified Soil Classification System (USCS). Select intervals were placed in sealable plastic bags and field- screened with a photoionization detector (PID) calibrated to isobutylene. Soil depths selected for laboratory analysis were sampled directly from the liners using a disposable plastic syringe and retained in one methanol-preserved and two sodium bisulfate-preserved volatile organics analysis (VOA)vials in accordance with United States Environmental Protection Agency (EPA) Method 5035 sampling protocol. The VOA vials were labeled for identification and stored in an iced cooler. None of the samples exhibited discoloration or an odor and none of the PID readings suggested the presence of elevated volatile organics concentrations. Soil samples were collected from boring 131 at 2, 5, 10, 15, 20, 25, 30, and 35 feet bgs; from boring B2 at 2, 5, 10, 15, and 20 feet bgs; and from borings B3 and B4 at 2, 5, 10, and 15 feet bgs. 3.6 Groundwater Sampling After soil sampling to the terminal depth in boring 131, a groundwater sample was collected by withdrawing the drill rods from the subsurface and installing a 3/4-inch diameter temporary monitoring well within the open borehole. After encountering drilling refusal at 20 feet bgs in boring B2, a groundwater sample was also collected by advancing the sampler fitted with an expendable steel point to the terminal depth and withdrawing the drill rods and installing a 3/4-inch diameter temporary monitoring well within the open borehole (i.e. hydropunching). The temporary monitoring wells consisted of 10- and 20-foot long, 0.010- inch factory-slotted polyvinyl chloride (PVC) screens at the terminal end and blank PVC risers from the top of the screen interval to the ground surface. Groundwater samples were retrieved from each monitoring well using a new section of 3/8-inch diameter polyethylene tubing fed through a peristaltic pump and conveyed into hydrochloric acid-preserved VOA Additional Subsurface Investigation Report PARTNER Project No.23-400162.14 July 31,2023 Page 6