Old Hand-Dug Well Discovered in a Wellhead Protection Area
You are drilling a new 10-inch public-supply well for a village. The proposed well is 600 feet from the existing municipal well and inside the state-approved Wellhead Protection Area. At 12 feet depth, your auger breaks into an old hand-dug well: 36-inch diameter, brick-lined, open at the surface, with water at 18 feet. It is not on any map, and the village's source water assessment lists the area as highly vulnerable. The village wants to keep the new well at the same location to save money. The old well is 25 feet from the proposed new casing. The village operator says the old well has been dry for years and can be filled with gravel from the top. The new well is needed before summer demand.
1. What risk does the open hand-dug well pose to the village's water supply?
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It is a direct conduit from the surface to the aquifer. The brick lining may be cracked, the top is open, and surface water, animals, septic effluent, road salt, or spilled chemicals can travel down the annular space or through the brick into the water table at 18 feet. Because the village's existing well is 600 feet away and the area is already rated highly vulnerable in the source water assessment, this old well is a potential contaminant source inside the WHP area. It also complicates the new well: the proposed 10-inch casing is only 25 feet away, so the old well could short-circuit grout, introduce contamination during construction, or create a preferential pathway after the new well is completed. Filling it with gravel from the top would not seal the aquifer.
2. Can the new public-supply well stay at the proposed location? What must be done with the old well?
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Do not complete the new well at that location until the old well is properly abandoned and the separation is evaluated against Nebraska well construction standards and the WHP plan. Abandonment should be done by a licensed water well contractor: remove the pump and debris, break out or perforate the lining as needed, disinfect, and fill or grout from the bottom up with an approved grout or fill material so no void remains; cap and document. The new well may still need to be relocated if the required isolation distance cannot be met or if grouting the old well cannot be verified. The village should not save money by leaving the old well open next to a new public-supply well. The state drinking water program should review the abandonment and the new well siting.
3. What notifications and WHP or source water protection follow-up should occur?
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Notify the state WHP and drinking water program, the local WHP committee, and the village's water operator; document the old well's location and abandonment in the source water assessment and WHP plan. Update the potential contaminant source inventory to mark the old well as abandoned. If contamination is suspected, sample the existing municipal well for the relevant parameters, such as bacteria, nitrate, and volatile organics, before and after construction. The village should review its WHP contingency plan and ensure the new well has a sanitary seal, proper grout, and a dedicated protection area. The driller should provide as-built logs and a sealed abandonment record; verbal assurances are not enough for a public water system.