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13 June 2023 Project No. 23-7200 Page 2 of 3 AdvancedGeo An Employee -Owned Company �.�I Based on review of the historical data it is unlikely that the remaining soil/groundwater impact has impacted the two wells proposed for destruction. Lastly, groundwater samples were non -detect for all constituents of concern (analytical data is attached). A copy of the Kleinfelder-prepared Phase // Environmental Site Assessment Update report documenting the well installations and subsurface investigation performed in October 2003 is attached. The two remaining wells (MW -1 and MW -2) are screened from 44 to 64 feet bsg with 2 -inch PVC casing and 0.020 -inch slots. Both wells have blank casing from near surface to 44 feet bsg. The boring logs (which show screen installed to 70 feet bsg, conflicting with the text body) are attached. 2.0. PROCEDURES As required, a health and safety plan will be prepared in accordance with Occupational Safety and Health Guidance Manual for Hazardous Waste Site Activities (National Institute for Occupational Safety and Health Administration, U.S. Coast Guard and U.S. Environmental Protection Agency, 1985). Prior to drilling activities, each proposed drilling location will be clearly marked, and utility clearance obtained through Underground Service Alert. Well abandonment/destruction permits will be obtained from the EHD; additionally, the EHD will be notified a minimum of 48 -hours prior to commencement of well destruction activities. Prior to well destruction activities, all wells will be checked for total depth and well integrity using a Solinst water level meter. Any obstructions found in the wells will be removed. Because groundwater samples from these wells have not been impacted, AGI proposes to destroy wells MW -1 and MW -2 by pressure grouting. Pressure grouting will include the removal of the well box and cap to expose the well casing. Each well will initially be filled over its entire depth with a thick grout mixture (no less than 6 gallons of water per 94 bag of cement). Any groundwater displaced by the grout mixture will be routed into properly labeled Department of Transportation (DOT) -approved 55 -gallon drums. Once the well is filled with the grout, the well head will be fitted with a pressure tight adapter and air pressure will be added at approximately 10 pounds per square inch (psi) of pressure for a minimum of 10 minutes. The added pressure will be used to force a significant portion of the grout mixture out through the screen, sealing the well. Additional grout will be added to the casing as required. The wells will then be over-drilled to approximately three feet below surface grade (bsg) using 8.25 -inch diameter augers; The top 2.5 feet of the well casing will be removed, and grout will be used to the fill the boring to near surface ("mushroom cap"). The remaining borehole will be finished at the surface with concrete to match the existing surface.