Power Jack Services – Drill Bell Bottom Pier

Drill Bell Bottom Pier

1. Pressure-check water supply lines for leakage.
2. Dig top holes (approximately 3′x3′x3′) underneath the perimeter grade beam of the structure at pre-determined pier placement sites.
3. Place all loose dirt on plywood for ease in clean up and to minimize disturbance of lawn and landscaping.
4. Use earth drill to drill one (1) twelve-inch (12″) diameter shaft out of bottom of the top hole at a pre-determined specified angle, as referenced by the structure. Then use a bell bit to drill a thirty-inch (30″) bell shaped bottom.
5. Place three (3) grade 40 #3 rebar tied on twelve-inch (12″) centers using stirrups. These are placed in bottom of hole and extend into top hole.
6. In top hole, place six (6) grade 60 #4 rebar in a crossing pattern. Tie #3 rebar to #4 rebar, using rebar ties.
7. Fill shaft and hole with 3,000 PSI concrete (five sack mix). Fill a minimum of twelve inches (12″). Trowel smooth.
8. Cover holes with plywood and mark off area for safety. Allow concrete to cure for a minimum of five days.
9. Remove plywood and place hydraulic jacks on pier cap. Place pre-cast cement cylinders beside hydraulic jack. Using a pre-determined sectional approach, raise areas of structure in small increments until the structure’s natural position has been attained.
10. Using steel shims to secure the lift of the structure, place steel shims on top of cylinder that was placed in Step 9 above.
11. Remove hydraulic jacks, then size and place another pre-cast cement cylinder beside the cylinder placed in Step 9, using steel shims to secure cylinders in place.
12. Place soil in top hole surrounding pier cap. Use a mounding approach to allow for soil subsidence. Remove excess soil from site.
13. Low pressure mud pump under slab area to fill voids left by raising structure. This is strongly required when lifting slab more than two inches.
14. Pressure-check water supply lines for leakage.
15. Discard plywood and rake areas free of debris.

General Notes

1. Reinforcing steel shall be deformed new billet steel bars in accordance with A.S.T.M. specifications A615 grade 40 or better.
2. Concrete shall have a minimum 28-day compressive strength of 3,000 pounds per square inch.
3. Slope-finish grades away from foundation to prevent pooling of water near foundation.
4. Should any unusual foundation, framing or soil conditions be encountered during construction, contact engineer.
5. Contact engineer prior to concrete placement for observation of excavations and reinforcing steel.
6. Reinforcing steel, pier diameter and depth may vary with individual site conditions.