Plugging a Flowing 1950s Farm Well

Gravel and a slab would leave the well as an open vertical conduit, only hidden from view.

Why it fails:

• Gravel is highly permeable. It transmits water between the shallow sand and gravel, the fractured limestone, and the surface.
• The corroded casing and the annular space remain. The slab covers only the top and does not seal the casing or the annulus.
• The well flows about 2 gpm. Continuing flow means water will keep moving through the gravel and casing, carrying contaminants and potentially changing pressures in the aquifer.
• The pit holds standing water and the casing top is below grade, so surface water can enter directly.

What Part 127 requires in principle: An abandoned well must be plugged by a registered well driller using an approved method that restores the confining layers and prevents vertical movement of water. That normally means removing obstructions, disinfecting, and filling the well from the bottom to the top with an impermeable material such as neat cement or bentonite. A flowing well requires special measures because the flow can dilute or wash out the plug before it sets. The driller must also file the required abandonment record. The goal is a permanent seal, not a cover.

The plug must be placed from the bottom up and must stop the flow.

Preparation:

• Remove the pump, piping, debris, and loose corroded casing. Disinfect the well. Do not leave the pit water in contact with the plug.
• Because the well flows, the driller may need to divert the flow, use a packer, or add an accelerator to the cement so that it sets before being washed out.

Volume calculation:

• Diameter = 12 inches = 1 foot.
• Area = 0.7854 x 1^2 = 0.785 square feet.
• Height = 45 feet.
• Volume = 0.785 x 45 = 35.3 cubic feet = 264 gallons.
• At about 1.15 cubic feet per 94-pound sack of neat cement: 35.3 / 1.15 = 30.7 sacks. Add 25 percent for loss and irregularity: about 39 sacks.

Placement:

• Use a tremie pipe to the bottom and pump neat cement or a high-solids bentonite grout upward. Keep the tremie submerged.
• If the flow is strong, stage the plug or use a packer and pressure grout. The driller should not dump sacks from the surface.
• Fill to the surface, cap the well, and mound the surface to drain away.

Verification:

• Confirm that the flow has stopped and that the grout volume used is consistent with the calculated volume.
• Sound the plug or check for settlement after it sets, and top off if needed. Document the method, volume, and final condition.

The abandonment must be documented and the site made safe.

Records and notifications:

• File the required well abandonment record with the state and local health department. Include the well location, depth, diameter, casing, materials used, volumes, method, date, and driller information.
• Notify the property owner and provide a copy of the record. The local health department should know that the flowing well has been addressed.

Safety controls:

• The pit is a confined space. Do not enter it without atmospheric testing, ventilation, an attendant, and a rescue plan. Standing water and decaying material can produce a hazardous atmosphere.
• Control the flowing water and electrical hazards. Use proper PPE and keep the rig and equipment stable around the pit.

If the casing collapses:

• Stop work, remove the obstruction, and determine whether the casing can be re-established or overdrilled.
• Pressure-grout the remaining void from the bottom up. If the well cannot be sealed by the planned method, contact the state and local health department before proceeding.
• Do not leave an open hole, a gravel-filled hole, or an unsealed annulus. Document the collapse and the revised plugging method in the abandonment record.