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12 October 2023 Project No. 07-1537 Page 2 of 3 AdvancedGeo An Employee -Owned Company Monitoring wells MW -1 through MW -10, MW -14 and MW -16 through MW -19 are single - completed with 2 -inch diameter polyvinylchloride (PVC) casing in 8 -inch diameter boreholes to a total depth of 50 feet below surface grade (bsg); monitoring wells MW -12, MW13, and MW -15 are single completed with 2 -inch diameter PVC casing in 8 -inch diameter boreholes to a total depth of 65 feet bsg. Monitoring well MW -11 is single completed with 2 -inch diameter PVC casing in an 8 -inch borehole to a total depth of 110 feet bsg. All nine soil -vapor wells are installed in a 4 -inch diameter borehole to a total depth of 5 feet bsg. AGI proposes to destroy all wells utilizing over-drilling techniques. The wells will be drilled out to the total depth of each well utilizing a hollow -stem auger drill rig equipped with either 6 -inch or 8 -inch diameter augers. All original well construction materials will be completely removed (including well casing, screen, filter pack, and annular seal) by the drill rig to ensure that no residual contamination is sealed within the abandoned borehole and a vertical conduit does not remain. All excavated borings will be completely backfilled to surface grade with a cement grout mixture (Portland type II) and covered with either concrete or asphalt, depending on the surrounding surface material. The grout mixture will consist of a ratio of six gallons water for every 94 -pound sack of Portland type II cement. The drill rig hollow stem augers will be utilized as a tremie pipe for installation of the grout seal. Rinseate generated during drilling and decontamination activities will be containerized in properly labeled Department of Transportation (D.O.T.)-approved 55 -gallon drums and stored on-site until proper disposal is arranged to a suitable non -hazardous waste facility. Additionally, soil cuttings, well materials and construction waste will be containerized in 20 -yard soil bins until proper disposal is arranged to a suitable non -hazardous waste facility. 3.0. REPORTING Upon completion of field work and disposal of waste, a well destruction report describing the activities and procedures, including documentation of waste disposal, will be prepared, and submitted to the San Joaquin County Environmental Health Department (SJCEHD) and CVRWQCB. The report will be in a format acceptable to the SJCEHD and the CVRWQCB and will be reviewed and signed by a California Professional Geologist. If you have any questions or require further information, please contact our office at (800) 511-9300. Sincerely, AdvancedGeo, Inc.