Siting a Bedrock Well on a Glacial Slope
Two adjoining 1.5-acre lots are being evaluated for a bedrock well. Lot A is on a gentle slope, 80 ft from a regulated wetland, and 150 ft from a neighbor's well. A mapped fracture lineament crosses about 60 ft upslope. Two nearby wells completed in the same schist are reported at 1.5 and 3 gpm, with depths of 200 and 300 ft. Lot B is in a shallow bedrock valley with seasonal high water within 3 ft of the surface; a nearby 400-ft hole was dry. The owner wants the highest possible yield and proposes drilling directly on the lineament at Lot A. The local health department has not yet issued a well permit, and the wetland commission has asked for a site plan. The driller has a 6-inch air-hammer rig and can drill a test hole before setting casing.
1. Evaluate the two lots from a hydrogeologic perspective. What are the likely controls on yield?
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In fractured schist, yield is controlled by interconnected fractures, not by proximity to a lineament alone. A lineament may reflect a fracture zone, but it can also be a topographic or soil feature; drilling directly on it improves odds but does not guarantee yield. Lot A has modest nearby yields (1.5–3 gpm), which suggests a marginally productive fracture system; 80 ft from a wetland may be a setback and contamination-risk issue. Lot B's shallow water table and nearby dry hole suggest limited saturated thickness or clay-filled fractures. The best approach is a test hole on Lot A, with fracture logging followed by a yield test. Do not promise high yield based on the lineament.
2. Outline the test-hole and yield-test program, including what would make you stop or relocate.
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Drill a 6-inch test hole, record penetration rate, water strikes, fracture depth, and casing stability. If the hole is dry or yields less than about 1 gpm after penetrating the target fracture zone, consider deepening or relocating before committing to a production well. If water is encountered, set casing and conduct a step-drawdown test followed by a constant-rate test (commonly 24 hours) with water-level measurement and recovery. Measure pumping level, specific capacity, and drawdown at the proposed pump setting. Stop or relocate if the hole intersects a wetland-connected fracture, if the water is turbid or contaminated, or if yield cannot support the house. Document all data for the well completion report.
3. What permits and setbacks apply before drilling, and how should the driller handle the wetland commission?
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The driller should not drill until the local health department issues the well permit and any required wetland approval is in place. In Connecticut, inland wetlands are regulated by the local wetland commission; a well within the regulated upland review area may need a permit or site plan showing disturbance, erosion controls, and setback. The private-well setback from the wetland and from property lines must be confirmed with the local health code and the commission. The driller should provide a scaled site plan, proposed well location, access route, and sediment controls, and avoid equipment tracking in the wetland. If the proposed location cannot meet setbacks, relocate the well or seek a variance. Keep the permit and completion report records.