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Looking for Ideas for an excavation

5037 Views 26 Replies 13 Participants Last post by  Upchuck
I am getting ready to bury a 10,500 gal water tank for a fire suppression system. The tank is going in the ground 9' from an existing building, the top of the footing is 5'8" below grade(1 foot footing). The dimension of the tank is 13'2" top to bottom, with either 12" of stone under it or on undisturbed soil, there is a 4' round sump station located 5-10' away from it/building that is 4'8" deeper than the bottom of the tank.
My question is this: the tank was supposed to go in back in the early part of sept when the water table was much lower, but the engineers and precast co have been redesigning if for the last month and a half and the water table is up substantially, finish grade on top of the tank is 410' and the water table is at 394.
I need to make sure that the building does not shift but with the water up I am worried about the 45* slope leading up to the existing footing is going to undermine. Driving sheet piling will cost 22K, I was going to underpin the corner originally, but with the water up that doesn't seem like a good idea. I obviously will de water and drop the table some, but am nervous about the proximity of the building. It is up to me for BMP to design the support.
Any ideas?
to add insult to injury the engineers wont answer the questin how much ground cover over the tank.:laughing: I guess it is not that important

Thanks in advance.
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have a well driller pop you a couple of wells in order to get rid of the water, get some 20' long sched 80 spreaders for your trench box, weld some plate on the open ends...start digging inside it, pushing it down as you go. most boxes are 8' tall, so you'd only have to concern yourself with the 45 degree taper from the top of the box up to the existing ground elevation. done it quite a few times.
It's funny how engineers often overlook the complexities of performing the work they design. It is also funny that it takes a lowly excavator to point it out in order to cause the design to actually become cost effective.

Why do engineers make the big bucks?????? I was always told it was because they save you money in the long run. I say it is the tradesmen who should make the big bucks, as we are typically the ones uncovering the pitfalls of designs with regards to the financial burden on the owner.

Way to go on the reality check Guyute!!!
well...i'm often very flattered because i have local seasoned engineers.."btw, 3 of my brothers are engineers" me, and say....hey, i'm going to email you plans for this project......this is what we want/need to do....this is what we'd like it to look like, this is what it needs to do....can you build it...what do we need to tweek to make it work for both of us? you need to work with these guys...get into a good working relationship with them. word gets around you're butt blasting their design....they'll work around me, i've seen it happen....they're not your them 40% of the way, they're climb mountains to get the other 60%
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Please I need the house idea to design a sewage disposal system in a water logged area, where the groud water table is at 1.2 meters to the surface, the component includes septic tank, soak away and check tanks
huh? your profile says you're an engineer?
i'm guessing this is a HO that wants to go to the rental yard this wknd...get some equipment, stop by at home depot, grab some material, and do it himself.
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