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,ffAkT February 12, 2020 Page 5 of 6 On May 29, 30, and 31, 2018, ATC supervised the advancement of two off-site monitoring wells (MW12 and MW13) on the property to the north. On May 29, 2018, permanent soil vapor sampling points SG-1 and SG-2 were installed on-site by Gregg Drilling and initial soil vapor sampling was conducted on June 4, 2018. A description of field activities and results were presented in ATC's Subsurface Investigation Report, dated August 6, 2018. On November 29, 2018, the off-site SDW was purged and sampled. No constituents of concern were detected in the groundwater sample. ATC performed an evaluation of site conditions with regard to the State Water Resources Control Board Low-Threat Underground Storage Tank Case Closure Policy. The results were presented in ATC's No Further Action Request report dated, August 29, 2019. ATC concluded that all of the media-specific criteria of the Low-threat Underground Storage Tank Case Closure Policy appeared to be satisfied and recommended that the site be closed. The CRWQCB concurred with the recommendations. On November 18, 2019, a Public Notice was sent to select property owners, tenants, and government agencies inviting them to comment on ATC's request for closure. The comment period ended on January 22, 2020, with no comments received by the CRWQCB. SCOPE OF WORK Planning and Permitting Following approval of the workplan, ATC will obtain the necessary permit documents from the SJCEHD for the groundwater monitoring well destruction activities. ATC will schedule field personnel and equipment, notify Underground Services Alert to locate underground utilities as required, and perform other necessary field preparation and job start-up activities. Well Destruction Activities The existing well network consists of 11 groundwater monitoring wells identified as MW1 through MW6, MW8, MW9, MW11, MW12, and MW13; four vapor extraction wells identified as VW1 through VW4; and two soil vapor wells identified as SG-1 and SG-2. The locations of the wells are shown on Figure 3. The groundwater monitoring wells are installed to depths ranging from approximately 89 to 150 feet bgs, the vapor extraction wells are installed to depths ranging from approximately 45 to 70 feet bgs, and the soil vapor wells are each installed to a depth of five feet bgs. Monitoring well MW11 was installed inside an 8%-inch diameter steel conductor casing that extends from approximately 0.5 to 130 feet bgs. All of the groundwater monitoring wells and vapor extraction wells are constructed of 2-inch diameter Schedule 40 poly-vinyl chloride (PVC) and the soil vapor wells are constructed of 1/4-inch diameter Teflon tubing. Well completion details are summarized in Table 1. Soil samples were collected from most of the boreholes associated with the groundwater monitoring wells during well installation activities and submitted for laboratory analyses. Available soil data associated with the monitoring wells are presented in Table 2. Groundwater quality data are included in Table 3. Based on the data presented in the aforementioned tables, ATC proposes to destroy MW8, MW11, MW12, and MW13 via pressure grouting. These wells will be destroyed by placing tremie pipe into the well casing and pumping neat cement grout slurry from the bottom of the casing to the top and