Cistern

[Darren]

Egon, there is an opening at the far end of the pit to the downhill side. That's for the water lines to feed and drain the cistern. It would have to be enlarged quite a bit to get anything in. I'm planning on setting the mixer on the flat around the pit. The slope below the cistern is too steep to set equipment on.

There's maybe a foot or so of earth on the top and then it's all rock from there on down. I stopped digging when the excavator couldn't break the rock out. I'm not sure whether the idea was to line the pit or the cistern. The liner wouldn't last long against the rock. If the cistern is built right, it won't leak.

I'm open to any ideas. Even something oddball might either work or trigger another idea or modification.

 

[gerard]

Have you considered bladders? There are bladders that are designed for long term fuel storage. Nice thing is when not full they are all collapsed on itself and you could probably haul it up on a trailer. Do a search on storage bladders and you'll find some companies that make them.

 

[em14]

It looks like Moss Road has a very good suggestion ... bury a plastic tank in the ground or just pour a pad and set either a metal or plastic tank on it ... I bet you could get one of those up to the site about as easy as building a cistern if not easier.
Leo

 

[Darren]

I checked the water tank link. A 50,000 gal tank costs around $75,000. It weighs somewhere between 15,000 and 18,000 lbs. Even if I had the money the weight and the length, 59' long, make it impossible.

Besides that those tanks require an in-tank pump. I was planning to let gravity do the work after the water was in the cistern.

 

[Egon]

If I'm understanding right your mixer will be above the cistern, How do you get the aggragate and cement to the mixer.

I'm having trouble visualizing the area but then that is a common problem for me.

Egon

 

[Anonymous Poster]

Re: Cistern Plan \"B\"

Coleman's Surplus has a lot of the military water bladders and the price overall would be a lot cheaper than cistern construction. They can be piped together with very little difficulty. These bladders were designed to work with mobil water plants for the Miltiary.

 

[Darren]

When my neighbor leveled off the bench on the hillside he also cut a road out to a pipeline R/W. I lucked out because I found an old road that ran from the upper pasture diagonally uphill across the pipeline.

The neighbor cut the road out to the pipeline so that it intersected the road coming up from the pasture. It's a really sharp angle but they intersect on the pipeline R/W

Sometimes when it's dry I can get a 2 ton single axle dump truck up to the pipeline and then backup to the bench. The pipeline R/W is too steep to turn around on. I did get one spot dug back farther into the uphill side between the pipeline R/W and the bench for turning around.

When I was hauling material from the pit, I'd either drive or winch the dump truck up to the pipeline then back up to the bench. On the way down with a load I would pull out to the one wide spot, backup so the truck's rear was toward the uphill side and then turn and drive the truck forward to the bench. Then I would back out to the pipeline R/W and then drive down the old road.

All the materials for the cistern will go up the same way. Either by using the truck or the loader on the tractor.

When I had the excavator the first thing I did was cut farther back into the uphill bank to increase the amount of level space. I don't have a lot of room but I should be able to stockpile enough stuff to mix the concrete.

I'll probably have to store some of it on the road between the pit and the pipeline R/W which will be ok because I'll leave just enough room to sneak the tractor by.

I've seen the bladders. I'm curious how long they'd last and how well they stand up to freezing temperatures.

 

[Egon]

If I read correctly your concrete mixing operation is above the level of the cistern.

Would it be possible to use a pipe, chute, canvas pipe to direct the concrete to where you want it? This is assumming the concret mixer can be moved around the site or you can move the concrete around the top of the site with equipment. Gravity would do the rest.

My only fears are continuity in the pour due to delays between mixing.

I would still consider a plastic liner just in case there are expansion/contraction cracks or some settlement occurs becuse of subsurface loading.

Again just thoughts which can be integrated with other ideas.

Egon

 

[Anonymous Poster]

"I've seen the bladders. I'm curious how long they'd last and how well they stand up to freezing temperatures. "
Bladders are a fantastic system of containment, that are hard to beat as long as you can protect them from UV degradation from sunlight. A bladder would probably suffer less damage from freezing than a concrete tank because it can flex.
You said you'll only be able to mix & pour about 1 yard of concrete at a time, so you will definitely wind up with problems in poured concrete. I've seen large tank pours, and in those situations, before pumps, it wasn't uncommon to have 20 men running georgia buggys from 3 truck mixers for 10 hours straight to preclude a seam from occuring in the pour.
A possible alternative if you use concrete might be the Gunite concrete placement. There are probably gunite contractors in the area, and it would be simple for them to add hose to reach the tank site.

 

[Darren]

The excavation is down to rock that the excavator couldn't break out. I had a 40,000 lb excavator that had a fair amount of muscle. Removal of any more material would mean using a jackhammer. I doubt settlement would be a problem. The idea of using a chute might work if I had several of them. I've seen 20' aluminum chutes. I'd need at least three to get to the far side of the pit not taking into account the depth of the pit. That means some sort of temporary structure to support them.

Seams are a potential problem. I'm not sure how fast the cycle time will be for mixing a yard. That's key. I'll probably have to test that. I can check the amount of time needed to load the mixer. I'll be using a tractor mounted weigh system to load. I doubt the base slab will be over 12" thick which means I have to get 28 yards or less into the pit. I'd like to run a minimal slump for maximum strength which could be a problem with the chutes.

I may have to look at some sort of admixture to ****** setting. Rather than relying on a handbook mix, I may have to get a mix designed. I need the minimum slab thickness which will carry the loads to minimize the amount of concrete.

The other problem with bladders is space. With a cistern as long as I can get the concrete into the pit and the wall design will allow it, I can get more capacity by going deeper. Every additional foot of capacity means another 4600 gals of water storage. Freezing shouldn't be a problem since the cistern is underground. For worse case situations I could include some sort of bubbler system.

I already know I'll need power for the level instrumentation. It wouldn't be a problem to add the capability to run a small compressor. In the past I've used fish tank air pumps to keep open areas in the ice covering a fish pond.

I appreciate the responses. You guys are bringing up some good points. Better now when things are still preliminary. Just talking this through is a big help.