sailorman2,
Sorry 'bout the link. The USACE must have changed it, 'cuz it doesn't work for me now either. Take a look at
and search for "5-134", which is Field Manual 5-134. The site has all of the FM series manuals in pdf. The manual will tell you a lot about installing pilings and was very helpful to me.
We used a 3" pump several times for several different piling installation attempts, but I think, in retrospect, that a 2" would do fine and the water-filled hose would be easier to handle, 'cuz it gets very heavy. Water velocity is more important that gross flow rate anyway.
If you can figure out a way to hold the piling erect with the base on bottom at the location you want to install it, that's a good way to start. I built a tripod out of 2"x4"x12' lumber with a triangular hole at the top and a pulley installed on the bracing on top for hoisting the piling and lowering it under some degree of control. The legs were secured by eye bolts and rope around the outside of the rig.
We were installing a 20' heavy creosote post with a bunch of fishing buddies using 19-20' boats. We had 4-5 people involved and could not have done it with less, because of all the labor involved. I think you could do short (<10') posts with 2-3 people, if you had a system worked out.
I made a 2"x10' stinger out of PVC pipe and attached a 2"x3" coupling so I could screw the stinger onto the end of the pump hose. Other than the excessive weight of the hose the arrangement worked well. You simply get the pump running well with a good flow rate out of the stinger, and raise the stinger to near vertical, so you can get a vertically-directed jet at the base of the piling. The jetting action will create a sand/silt slurry at the base of the piling and you can work the stinger around the piling as needed to maintain the sediment in suspension. The piling will advance into the deepening hole automatically from its own weight.
We did it all with one pump and stinger, but two would probably work better, if you can swing it, so you can jet from both sides of the post.
During jetting, the intake hose was placed with a filter basket at some distance away from the piling location to minimize sediment uptake.
Short posts are a piece of cake. Much deeper ones are a challenge, because you need a way to stabilize the long, heavy piling and you have to work with some sort of derrick, tripod, etc. to handle the elevation. Also, you need to be able to adjust stinger length to get a longer one as you advance. If you quit jetting to make adjustments, the hole closes in and it's game over, requiring you to start the hole over.
The other issue is the huge crater that's left when you get the post in place and it's at the proper depth. We kept falling into the crater (3-4' deep) while working close to the piling. I think that it would be worth the extra step to have somebody carefully manage the intake hose with the sediment filter removed, and use it like a vacuum to suck up sand/silt and pump it into the remaining crater, filling it up to at least level with the bottom or perhaps above level. Then the fill should be compacted by stomping around on it or tamping the fill material with another post.
One of the downsides of jetting pilings is that the process destroys the soil cohesion, so backfilling a jetted hole around a piling leaves a much weaker piling completion than you might achieve by driving the piling. I think the manual describes that specific problem. So, anything you can do to improve the lateral strength of the piling foundation by backfilling and compacting would be helpful.
Hope this description helps. Lots of luck with your installation and may Allah give you strength!
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