Abandoning a Flowing Well Near a School Replacement Well
A school has an old 6-inch steel well at 95 feet that flows about 2 gpm at the surface. The casing is corroded at the top, the cap is missing, and the well is 25 feet from a new replacement well that serves the school. The old well is not used, but the school wants to abandon it before the new well is put online. The casing is firmly set and cannot be pulled. The static water level is at grade, and the well penetrates 30 feet of sand and gravel over shale. The driller has neat cement, bentonite grout, a tremie, and a packer. The school wants the work done during spring break, with no interruption to the new well. The local health district asks for a copy of the sealing record.
1. What abandonment method and materials should be used for this flowing well?
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The old well should be abandoned by a licensed driller using an approved continuous sealing material, not sand or gravel. Because the well flows at the surface, the crew must first control the flow and remove the pump, wiring, and any obstructions. A packer or weighted tremie can be used to place neat cement or approved bentonite grout from the bottom to grade without dilution. For a flowing well, neat cement is often the more robust choice because it can set under water and resist flow. The seal must fill the entire well bore and casing to grade; a partial plug or sand backfill would leave a pathway between the shallow sand and gravel and the shale aquifer. The corroded top should be cleaned or removed so the seal is continuous.
2. How should the driller protect the new replacement well during the abandonment?
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The old well should be abandoned before the new well is placed online, and the work should be sequenced so the new well is protected from cement, turbidity, and pressure changes. The crew should control the old well's flow rather than letting it discharge uncontrolled near the new well. The packer and tremie should be set and the grout placed carefully so cement does not travel through the formation into the new well. The new well should be capped and its opening protected during the work, and any disturbance to its water level or turbidity should be observed. Because the wells are only 25 feet apart, the driller should avoid simultaneous pumping or development that could pull grout or fines toward the new intake. The sealing record should note the proximity and the protective measures.
3. What records and notifications are required, and what should be done if the old casing is too corroded to seal reliably?
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The driller should prepare a well sealing record that identifies the well location, depth, diameter, casing, water level, flowing condition, materials used, quantities, method, date, and driller license information. The record should be submitted to the Ohio Department of Natural Resources, Division of Water, and a copy provided to the local health district as requested. The driller should not wait until the next routine reporting cycle; the sealing report should be filed promptly under the applicable rule deadline. If the casing is too corroded to hold a reliable seal, the driller should clean, perforate, or remove the unstable section as needed and place the seal so it bonds to competent casing or formation. The driller should document the condition and the corrective method rather than covering a defective casing with a shallow plug.