filling material for underground strucutre
filling material for underground strucutre
(OP)
We have been tasked to close under ground storage tank in place. The tank was constructed but was never used. The tank top is made up with 1 ft concrete slab. The top of the concrete slab is 5 ft below the grade filled with soil. The tank is 130 ft long 35 ft wide and 25 ft deep (it's huge!)Void volume is close to 5000 cubic yard. One idea is to use cement/sand mixture which could flow. This is not done under any environmental law and we don't have to do any sampling.
Any comments on the idea of using cement/sand mixture? Any thoughts on how to implement it? What would be the cost of flowable fill per cubic yard?
Thanks for your responses!
Any comments on the idea of using cement/sand mixture? Any thoughts on how to implement it? What would be the cost of flowable fill per cubic yard?
Thanks for your responses!





RE: filling material for underground strucutre
Back in the early 1990's, I designed a similar application for a "major theme park" to fill the voids of very large artificial rocks. Worked well.
RE: filling material for underground strucutre
I'd bet it would be less expensive to break in the top slab and fill with ordinary earth handling equipment and hauled in earth than to work up mixtures and somehow get it into the tank and completely fill it.
RE: filling material for underground strucutre
If you had the lid off, then you can just fill it with gravel, sand, etc.
If you have to leave the lid on then using a flowable fill of some kind seems like a good idea. You're probably talking some pretty serious money for that much flowable fill.
It seems like the cost of concrete varies quite a bit from location to location so you will probably get your most accurate answer on pricing by calling a local supplier.
Just had another idea. I'm not sure if it would work, but could you use a sand/water slurry, then devise a way to get the water out of the tank? You could pump the water out or poke a hole in the tank to let it drain out if the water table isn't too high.
RE: filling material for underground strucutre
RE: filling material for underground strucutre
1. Flowable fill-material cost is high and labor cost is low since no mechanical compaction needed.
2. Well graded gravel - no mechanical compaction needed. Remove concrete cover. Fill the space up to the top of the concrete storage. Cover the top with non-woven geotextile. Place another geotextile with enough area to cover the rest of the gravel. The gravel layer above the concrete storage will be wrapped with the geotextile just like a "burrito wrapped". This geotextile prevents tiny particles migrating out of the sorrounding area into the gravel area.
3. Gravel mix-material cost is relatively cheap, hauling cost, and compaction cost.
Option number 2 I think is the best.
RE: filling material for underground strucutre
RE: filling material for underground strucutre
Secure/remove whatever access there was. Is it failing? If they need the space in future, there will be just more debris to remove.
Dik