Grouting, Sealing, and Well Abandonment
What the exam tests
This domain tests the annular seal and what happens at the end of a well's life. Questions often ask for grout volume, grout method, or the required abandonment seal.
Core rules
- Grout is placed by the tremie (pump-and-tube) method from the bottom of the casing upward, so the tube stays submerged and the annulus is not bridged.
- Approved materials include neat cement, cement-bentonite, and bentonite grout mixed to the manufacturer's density; the seal must be continuous to land surface.
- Abandonment requires a certified well contractor, removal of obstructions, disinfection, and filling so that no vertical pathway remains. The upper portion is sealed with grout and the casing is cut off and capped below grade as required.
- A well abandonment report must be filed with the state; the well is not "closed" just because the pump is pulled.
Worked example
A 300-ft, 6-inch well is to be abandoned with a full grout column. Casing area = π/4 × 6² = 28.3 in² = 0.196 ft². Volume = 0.196 × 300 = 58.9 ft³. At 1.15 ft³ per sack, that is 51 sacks; with 10% loss, plan on 56 sacks. If the rule allows sand or gravel in the lower portion and grout only in the upper seal, compute the grout only for the sealed interval - but never leave the upper 20 ft unsealed.
Traps
Grouting from the top; mixing grout so thin that it settles and leaves a channel; using the casing ID instead of the annular volume; and forgetting the report or the disinfection step.