Well Construction and Siting
This domain tests whether you can put a well in the right place and build it so it stays clean and productive. Expect questions on setbacks from contamination sources, casing and grout design in overburden versus bedrock, screen and gravel-pack selection, well development, and how a yield test is run and reported.
Location
- Keep the wellhead upslope and as far as possible from septic tanks, subsurface disposal fields, sewer lines, fuel tanks, and manure or road-salt storage. Maine's minimum separations include 50 feet from a septic tank and 100 feet from a disposal field. Measure to the nearest point of the source, not to its center.
- Finish the head above grade with a sanitary seal, a vermin-proof cap, and a pitless adapter, so surface water cannot run back down the casing.
Casing and completion
- In sand and gravel, case through the unconsolidated material and set a screen with a properly graded gravel pack. In bedrock, seat the casing into competent rock and grout the annulus.
- Develop the well by surging, air-lifting, or bailing until the water clears, then test yield. Record static level, pumping level, pumping rate, and test duration. Specific capacity, in gallons per minute per foot of drawdown, is the number the completion report actually needs.
Worked example
A customer proposes a well 40 feet from the septic tank and 70 feet from the leach field, on ground that slopes downhill from the field toward the proposed spot. Both separations fail, and the slope drains contaminated water toward the hole. The answer is not a better cap: relocate the well upslope and beyond both setbacks, then document the new distances.
Traps that cost marks
- Measuring to the septic tank but forgetting the disposal field.
- Ignoring surface drainage and groundwater flow direction.
- Stopping the casing at the first refusal instead of in solid rock.
- Reporting a yield with no pumping level or test duration attached.