Abandoning a Dug Well and a Flowing Test Hole
A property in Monroe County is being redeveloped. The site has a 36-inch-diameter hand-dug well, 22 feet deep with a brick liner, and a 2-inch steel test hole drilled to 90 feet that flows about 1 gpm at land surface. The dug well is 35 feet from a wetland and 80 feet from a neighbor's active drilled well; the test hole is 15 feet from the foundation excavation. The contractor plans to pull the old pump, dump three cubic yards of crushed stone into the dug well, and backfill the test hole with drill cuttings. The town has issued a demolition permit but no well abandonment approval. The owner wants to finish before winter and asks whether the stone and cuttings are acceptable. The water table is at 8 feet; the upper 10 feet of the dug well is in sandy fill.
1. Evaluate the contractor's abandonment plan. Why are crushed stone and drill cuttings unacceptable here?
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Reject the plan. Crushed stone and drill cuttings are permeable and may contain contamination; they do not create a low-permeability seal. The dug well penetrates sandy fill and is close to a wetland, so it can act as a vertical pathway for surface water and shallow groundwater. The flowing test hole is worse: a 1-gpm flow can carry grout away and can connect aquifers if it is merely backfilled with cuttings. The excavation 15 feet away also creates a risk that the test hole will undermine the foundation if it is not properly sealed. A demolition permit does not authorize well abandonment. Work should stop until the local health department or other responsible authority approves a written abandonment plan that specifies methods, materials, and verification.
2. Design the abandonment sequence for both wells. Include materials, flow control for the test hole, and verification.
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Remove the pump, piping, debris, and unstable liner material. Disinfect the openings, then fill and seal them so they cannot transmit water. For the 36-inch dug well, a full-depth grout plug is practical because the volume is modest. Place neat cement, concrete, or approved bentonite/cement grout by tremie from the bottom up, or use an approved clean fill in the lower portion only if the design still provides a continuous low-permeability seal across the full opening. Do not bridge the grout on the brick liner. For the flowing test hole, control the flow first with a packer or valve, then pressure-grout with neat cement or approved bentonite grout from the bottom to surface. Verify grout returns, volume placed, and final seal. Cap both locations, record depths and materials, and confirm the test hole is not flowing after sealing.
3. What approvals and records are required before and after abandonment?
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Obtain abandonment approval from the local health department or other authority having jurisdiction before work begins; a demolition permit alone is not enough. Notify the neighbor with the active well if the work could affect it, and protect that well during grouting. Keep a written record for each abandoned well that includes location, diameter, depth, casing or liner details, static water level, flow, method of abandonment, materials and quantities, date, and driller or contractor. Submit the required abandonment report and provide a copy to the property owner. If the flowing test hole cannot be sealed or if grout is lost, stop and revise the plan rather than hiding the problem under fill.