How Much Rock?

[Big Barn]

I’m guessing 2 tri axel loads and a smaller truck load using the previous posters math of 29.8 yards.

^^^ agreed^^^

 

[Big Barn]

Funny how terminology varies region to region. Around here a three axle truck ( one steer and two drive axles) is called a “tandem”.

Two front steer axles and two rear drive axles is a “tandem-tandem”.

One front steer and three drive axles is a “tridem”

 

[4570Man]

^^ Because I want to be able to draw water out. The plan is to set a 6-8" pipe down the center and surround it with rock. The bottom few feet of the pipe would be perforated to allow water in but not rock. I'll drop a shallow well point in the pipe, so I don't want mud or sand in there. The cistern is old, cracked and leaking, so rainwater settles int to it. I need to be able to pump that rain water out to keep the surrounding ground dry. If it gets full and seeps out, I have a giant muddy mess next to the house.

That will also give me an emergency water supply in some sort of disaster, though it will require boiling or other treatment.

So, why fill it at all? Because it's cracked and I don't want to risk it falling in on itself.

Rock will prevent collapse, but allow water collection.

Any gravel would do that. Why go through the difficulty of trying to use big rock?

 

[Diggin It]

Any gravel would do that. Why go through the difficulty of trying to use big rock?

I don't want to use big rock. I figure 1-2" would do the job and not get into the pipe. I could drill a couple of dozen 1/2" holes in the pipe instead of a bunch of smaller holes if I used smaller gravel. I don't know of a perforated pipe that diameter available locally, though I might be able to use the 4" I can find if I knew it wouldn't crush over time.

To complicate things, I can't get a tri-axle in my driveway and I wouldn't want that much weight on my blacktop at one time. There are a couple of guys here with single axles that could bring 5-6 ton or so each load. I'd have to see how they would price multiple loads over a couple of days.

It's only about 10-15' feet off the driveway, but not in a position they can dump direct, so I'll have to do it by loader which will take time.

 

[LD1]

Where are you located?

Around here, what we call #4 gravel is what I would use. Roughly golf ball sized.

30 yards is about 45 tons if gravel. A little less if limestone.

 

[Gary Fowler]

The larger the rock, the more water it will hold for your emergency use although I don't know how you could justify putting a pump into it for no more water than you will get. For the cost of gravel and labor to install it, you could likely put a sealant into the cistern so it doesn't leak. I seriously doubt that cracked concrete is going to collapse inward on a round structure. They are pretty well self supporting. If it were square, it might fold inward, but not a round structure. Pressure forcing inward would have to crush the concrete in order to collapse, outward pressure from the water inside would have a better chance of causing a failure, but with solid dirt around it, that is unlikely also.

I would fix it to hold water if you really need the water, otherwise I would fill it in with dirt, not rock, so there is no possibility of water seepage causing mud as you now have.

 

[Jstpssng]

I did similar to what you had when I had my spring dug, except that I used 10 yards of gravel screenings. Since then I have read that it was the wrong material to use. If you use finer material it will act as a filter for water percolating down through.