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to be sealed. 1. Perforate the casing opposite the interval 2. Place a packer or other sealing device in the casing below the bottom of the perforated interval. 3• Use a dump bailer or grout pipe to place grout in the casing opposite the interval to be sealed. Sufficient grout shall be placed to fill the annular space and extend out into the strata to be sealed-off. 4. Place a packer or other sealing device in the casing above the perforations. 5. Apply pressure to the top packer to force the grout through the perforations into the interval to be sealed. 6. Maintain pressure until the material has set. APPENDIX C 7. Drill out the packers and other material SUGGESTED PROCEDURES FOR remaining in the well. DISINFECTING WELLS Frequently, an assembly consisting of inflatable (balloon) packers and grout pipe is used. The packers are placed to enclose the interval to be sealed, they are inflated and the grout pumped down the hose (which passes through the upper packer) into the interval to be sealed. Water is then pumped into the interval, squeezing the grout through the perforations. When the grout is sufficiently hardened, the packers are deflated and removed. Liner Method. Where the annular space between the casing and the wall of the drilled hole is minimal, the liner method can be employed. to be sealed. 1. Perforate the casing opposite the interval 2. Place a smaller diameter metal liner, about 2 inches (50 millimetres) less in diameter, inside the casing opposite the perforated interval to be sealed, and extend it at least 10 feet (3 metres) above and below the perforated interval. 3. Provide a grout retaining seal at the bottom of the annular space between the liner and the well casing. 4. Extend the grout pipe into the opening between the liner and casing, and fill the annular space with grout in one continuous operation. 5. The botton end of the grout pipe should remain submerged in the sealing material during the entire time it is being placed. The grout pipe is gradually with- drawn as the sealing material is placed.