The foundations for poles are just as important as the structure above ground. The pole back fill should be capable of withstanding structure reactions. Pole-setting equipment should be moved clear of the structure site prior to back filling.

Differences in ground elevation at each pole location, and pole length tolerances permittedby ANSI O5.1-1987 [9] should be considered to ensure a level structure. The tops of poles should not be cut. If cutting is necessary, the pole top should be covered with a mastic-type cap.

Under no circumstances should the butt of any pole be cut. The design engineer should specify a minimum hole depth. The actual hole depths required to obtain a level structure are the responsibility of the installing contractor.

Digging operations should not be too far in advance of the setting operation. Holes open too long may deteriorate due to ground water seepage and/or heavy rains and increase the chance for accidents. Unattended pole holes should be temporarily covered. All Local, State, and Federal safety regulations must be met.

Structure Alignment
When the structure is set and the load line completely released, the structure should remain plumb and level. If the structure is not plumb or the crossarm is not level, additional material will have to be placed under one pole. The additional material should be approved by the design engineer.

Pole Holes
All holes should be in the correct locations and large enough to provide a minimum of 6 in of space for tamping around the pole to the full depth of the hole. Pneumatic tamping equipment is recommended to expedite the setting operation.

The poles should be placed to prevent damage to the structure grounding materials. Poles not required to be raked should be set plumb and in alignment. Unless otherwise specified, structures at angles should be set to bisect the line angle.

The holes may be back filled with earth excavated from the hole, provided this material can be properly compacted. Frozen material for back fill should not be permitted.

The back fill should be compacted to a dry density not less than the natural in-place dry density of the surrounding earth. Since the measurement of the density may not be practical, no more than one shoveler should be utilized for three tampers.

Front-end loaders are not recommended during back filling. Back fill should be banked and tamped around the poles to a height of 12 in above the natural ground surface.

Excessive water should be pumped out, leaving not more than 6 in of water in the bottom of the hole, and 6 in of granular material should be placed to firm up the bearing surface. Care should be exercised where pumping will cause excessive sluffing of the bottom of the hole.

Casing should be used where moving water and/or gravel is encountered, working the casing down as the material and/or water is removed.

Related post

No comments: