Method to Remove Temporary Wood Lagging

[justbuildit]

I have been on several projects that use W14X145 or 120 soldier piles with 3x12 wood lagging. How should the lagging be installed to aid in removal without cutting the lagging. Is there an easy way out there to remove the lagging from the bottom up as backfill progresses? Our guys will just cut the lagging creating shorter pieces that cannot be resused on the next project without reducing the pile spacing. We generally space the piles 8'6" on center and use 8' long lagging. We install the lagging behind the front flange. How do you get the lagging loose to aid removal. Has any tried wrapping wire rope around all the lagging during installation and pulling up with a forklift or crane during removal? Our excavations typically are 10-15 ft deep. Thanks.

 

[crossframe]

I've seen contractors use lagging that is cut a little shorter than you describe (but not shorter than the flange-to-flange distance!), then wedged into place between the webs. To remove it, the wedges are removed to hopefully allow enough room to get the lagging out. I don't believe that every piece has wedges, since the more you remove, the easier it becomes.

 

[civilperson]

If steel plate is used between the piles, then a lift handle at the top can be used to slide the plate up to match the fill elevation with the bottom of the sheet. Reusable but a storage and handling chore.

 

[PEinc]

You take out the wood lagging the same way you install it, piece by piece. a few at a time, except you remove it while backfilling the wall. However, you may need to cut a board here and there to help relieve the confinement for other boards.

 

[justbuildit]

When you say you wedge it between the wedges, do you mean you put a wedge inbetween the lagging and the flange at each end of the lagging, then by removing the wedges you create relief to ease the removal?

 

[PEinc]

Lagging is not usually wedged in place. It is usually tucked behind or attached to the front flanges of the soldier beams. The lagging boards are cut at least half a flange width shorter than the center to center spacing of the soldier beams. The lagging should have full contact with the dirt behind the lagging.

 

[PSlem]

If you reuse you may want to consider contact sheeting as you could also reuse the clips. You would only lose the studs welded to the pile faces.

 

[PEinc]

Contact sheeting clips are expensive. Most contractors use low-carbon, threaded studs hand-welded to the soldier beams with 3" x 8" plates. The trick is to buy uniform width lagging booards so that the studs can be installed at a constant spacing. Ramdom width boards are cheaper to buy but more trouble to install when using clips or welded studs.

 

[VAD]

Justbuildit

Just some thoughts: It is presumed that your lagging is all horizontal and not a combination of vertical boards and horizontal members.

Instead of placing the lagging behind the flange as is customarily done. Could you consider welding some u -shaped rebar onto the piles with the free end of the u's turned upwards to retain the lagging. This would be done as you excavate so that lagging can be positioned on the outside of the flage or face of the flange. This way the lagging can be dropped in place. On backfilling, the lagging can be removed from the bottom upwards as the backfill progresses.

Extr time and material is required but you may be able to come up with a scheme that is efficient- eg predrilled holes in the flange and use of a threaded anchor bolts with a 90 degree bend and sufficent hook length to retain lagging.

Would the use of screw piles for the depth of excavation considered.

 

[DRC1]

Generally we remove the top 5 feet by sliding back 7 out. Belw that it is more cost effective to abandon

 

[DRC1]

Opps... That's "sliding back & out."