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28 October 2022 AdvancedGeo <br /> Project No. 02-0926 An Employee-Owned Company <br /> Page 2 of 2 <br /> will be notified a minimum of 48-hours prior to commencement of well destruction <br /> activities. <br /> Prior to well destruction activities, all wells will be checked for total depth and well integrity <br /> using a Solinst water level meter. Any obstructions found in the wells will be removed. As <br /> part of closure proceedings, AGI proposes to destroy wells MW-3, MW-5 through MW- <br /> 14, EX-1, EX-2, DPE-1, and DPE-2 by over-drilling. The wells will be drilled out to the <br /> total depth of each well utilizing a hollow-stem auger drill rig equipped with either 8-inch <br /> or 10-inch diameter augers. All original well construction materials will be removed <br /> (including well casing, screen, filter pack, and annular seal) by the drill rig to ensure that <br /> no residual contamination is sealed within the abandoned borehole and a vertical conduit <br /> does not remain. <br /> The boring will be completely backfilled to surface grade with a cement grout mixture <br /> (Portland type II) and finished at the surface with native soil or concrete to match the <br /> existing surface. The grout mixture will consist of a ratio of not more than six gallons of <br /> water for every 94-pound sack of Portland type II cement. The drill rig hollow stem augers <br /> will be utilized as a tremie pipe during deployment of the grout mixture. Any groundwater <br /> displaced by the grout mixture will be routed into properly labeled Department of <br /> Transportation (DOT)-approved 55-gallon drums. All investigation derived waste will be <br /> containerized in properly labeled DOT-approved 55-gallon drums and disposed as a non- <br /> hazardous waste. <br /> 3.0. REPORTING <br /> Upon completion of field work and disposal of waste, a soil sampling and well destruction <br /> report describing the activities and procedures, including documentation of waste <br /> disposal, will be prepared, and submitted to the SJCEHD. The report will be in a format <br /> acceptable to the SJEHD and will be reviewed and signed by a California Professional <br /> Geologist. <br /> If you have any questions or require further information, please contact our office at <br /> (800) 511-9300. <br /> Sincerely, <br /> AdvancedGeo, Inc. <br /> V <br /> Kylie E. Kucera Daniel J. Villanueva <br /> Staff Scientist Senior Geologist <br />