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Michael Kith 41RION San Joaquin County Environmental Health Department 2 December 2019 Page 2 Evaluation of Alternative Destruction Methods As described in the original variance request, per client and contractor safety standards, overdrilling within 5 feet of an underground utility poses an unacceptable safety hazard. In a phone call with SJCEHD on 22 November 2019, SJCEHD requested that Orion evaluate the feasibility of destroying the 12 ozone wells by perforating the well casings using explosives followed by grouting. Because the wells are located at active petroleum fuel terminal facilities and in the proximity of underground high-pressure fuel distribution systems, client safety standards prohibit the presence or use of explosives at the site. As a result, this well destruction method is not a feasible alternative. Recommendations In order to meet the regulatory agency directive of destroying all former ozone injection wells, Orion recommends destroying wells OS-57, OS-48, OS-47, OS-46, OS-45, OS-1613, OS-44, OS-15B, OS-43, OS-13B, OS-41, and OS-12B by grouting. Overdrilling and perforating the well casings using explosives are not feasible alternatives. For these 12 wells, Orion proposes to amend the SJCEHD standards for grouting by applying pressure to the wellheads after grouting in order to ensure sealing materials are effectively emplaced. Orion will destroy each well using the following procedures, in accordance with SJCEHD standards for grouting: 1. Tag the total depth of the well to confirm the well casing is free of obstructions. 2. Clear the annular space around the well casing using air-knife to a depth of approximately 3 feet below ground surface (bgs) and cut and remove the well casing to a depth of approximately 2.5 feet bgs. 3. Fill the well casing with neat Portland cement. ? 4. Apply at least 20 pounds per square inch of pressure to the wellhead and I V maintain pressure for 5 minutes. 5. Fill any void space in the well casing with neat Portland cement. Allow cement to overflow the top of the well casing and fill the cleared boring to a depth of approximately 2 feet bgs. 6. Complete the surface with a 2-foot-thick concrete surface seal. S:\Clients\52STTC\LTR\LTR004.docx 12/2/19