Ok here's my problem. I was hired to replace a grease trap. 12.5 feet deep. where I live is in a severe drought but my pit keeps filling with water. Obviously there is a water leak somewhere leaching back into my ditch. how can I get the mud and rock in the bottom of this ditch to solidify so I can set a 12k pound grease trap on a solid base. I've tried using 1.5" crusher run and it didn't work any help would be greatly appreciated I posted here because you guys/gals use big equipment and hopefully have had similar problem. I have a city fire main 20-30 feet from my hole that I believe is where the problem is coming from or I have a 8" private sewer main that is broken. either way I need a solution. that doesn't involve finding the leak if possible. can mixing lime in my ditch make it solid enough to compact?:Banghead:Banghead:Banghead
I would use 1 by 4 rock, we have used it as a base, then put a 3/4 rock on top. First push all the muck to one end, then fill backhoe bucket with rock and push bucket toward the end with the muck. This may require someone hand shovel rock from the bucket. You may also just need to muck and rock at the same time, if the muck is really bad
Any excavation with water entering is considered class III, slope 1 1/2 to 1 or trench shield. I would hope that you have a shield in place, Preferably 4 sided. That should slow down the water a bit. You can do the rock the opposite way also. Just pull as much of the muck to the hoe. then dump rock in the clean end, slow pull the muck again, while someone shovels rock behind the bucket. If it's really mucky, then you may need to pull the muck and rock behind the bucket as you dig.
Yeah you may need to over dig slightly and do what heavy says, put in 4 inch or maybe even 6 inch rock and then add your 3/4 or 1 inch bedding. That deep with the water just make sure you are sloped or benched properly or the best bet is to use a shield.
Ill add to what these guys have stated. Build yourself a kelly well. Take a piece of pipe big enough to get a 2 inch submersible pump inside. Take your chop saw and cut slots in this pipe. Pick a corner of the excavation that is out of your way. Dig an area deeper than your final grade, as deep and you can. Now put your pipe in, and backfill with a clean open graded stone that will let water pass through. Dewater long enough to make your final grade, place any stone you need for a base, and then set your grease trap and backfill. Put a choker around your well pipe, and yank it out, job done.
Around here we deal with ground water or dewatering in general three ways, using the most efficient method to accomodate the amount of water we're having to cope with. One, a wellpoint system. Two, hydraulic submersible pumps. Three, 3" trash pumps minimum. OSHA does require control of water in any trench or excavation prior to allowing any personnel into an open excavation. Where trench collapse is a concern we'll step ditch then dress the sides with #57 stone, if too deep and unstable an excavation we are required to use trench boxes "mules".