Existing Water Tank Support

I looked at a 16 ft. diameter, 45 ft circumference and 10 ft. height for an existing Redwood Water Tank. It is full of water......... It is supported underneath by 4x6 and posts about everywhere. The foundation is faulty, the water is necessary for the Trailer Park and the owner wants me to pour a concrete slab under that..............tank...... There is no room to speak of, lifting the tank is out of the question, a decent footing, and steel in a slab would be impossible to do. The tank leaks also........... What does the owner think? The ground under the tank is wet and soggy......... You cannot crawl under it. The tank also has sides that go down past the floor. The floor is keyed into the wall. Steel straps support the sides of the tank. What does a guy do? You cannot drain the tank...........hum? any ideas? jloomis
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wrote:

Just the water weighs 125,000 pounds.
Bring in a temp tank or truck. Pump the water into the temp and hook up temporarily. The waterlogged tank may weigh 10,000#. If it is leaking, it needs reworking or the bands tightened. It can be moved intact using cable bridles and a pretty stought crane. Either move it aside while pouring the slab or pour next to it and move it over. When setting it down, make sure the 4x4s are perpendicular to the bottom planks.
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Thanks for the thoughts. I spoke with the owner concerning these issues. I would be afraid to lift the tank since it is "grandfathered into its area, and "settled" in a way that putting a new foundation under it would give it a new posture.(leaks) tough one. Hey, Thanks for the ideas. jloomis

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jloomis-
You've got a tough one there. Owner / situation is placing so many constraints on the system that is will be close to impossible to fix it properly.
As Andy said, you've got ~15,000 gallons ~125,000 lbs of water & my estimate ~ 6,000 lbs of water logged tank.
The leaking tank has caused the soil to fail. You need a redwood tank expert (is the tank in Northern Cal? Mendo?) My suggestion would be to try to stop the leaks OR collect the leaking water & channel (or pump) it away so the soil can dry out.
It's going to be very difficult to deal with the soil while its soggy.
Andy's suggestion of the temp water system / tank is the way to go.
Get the leaks under control, let the local soil dry out (trench & pump or drain). Consider a new slab very nearby (if the soil is dry enough). Build a new slab, crane the tank onto the new slab & refill it. Fix the leaks (tighen straps as you go) or just properly deal with the leakage water.....are be talking about gallons per minute or gallons per day?
If you can pour a new slab you'll only have to crane the tank once. If the tank has to wind up back in the same place you'll need two crane visits. :(
A 16' x 16' (min) concrete slab of decent thickness (& the dry soil under it) will easily support the full tank but with saturated soil you'll always be in trouble.
You need a decent foundation with a provision to handle any potential water leaks, like a curb & a sump or drainage channel depending on the relative elevations of things.
That redwood tank should be very forgiving of repositioning, it wood & wet.
Maybe the owner should consider selling the redwood & using the $'s to buy a new plastic or metal tank. It's most likely old growth r/ w...worth a fair amount for sliding & trim.
This is relatively simple job IF the owner allows you some wiggle room.
cheers Bob
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Thanks for your information. There are a lot of problems with this situation. One is that this is a trailer park with little or no room. The water is used by the residents. The tank leaks like a sieve....... The side are longer than the bottom.......... A foundation would need to be built that would support the floor and let the side hang down. The soil is compromised........ The best thisng to do is build a foundation elsewhere and put new tanks on it.....Plastic....... Anyway........the owner realizes the situation and his Dad put this in 24 years ago on post and beam.......4x6.......on earth....... It is not a simple fix. jloomis Mendocino County
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Feel your pain. A trailer park doesn't have much allowance for upkeep regarding water or anything else for that matter.
Ideally, should use a temp storage tank of minimum capacity. Repair or replace the current tank, plumbing and foundation. Dave
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If the tank isn't lined, it may be leaching into the park's water supply.
Install a plastic liner into the existing tank & couple the water service into that. That would stop the leaks and allow the ground to dry out over a period of a few weeks. Reinforce the existing tank at this time with stainless banding.
Then place new individual piling footings & shore up the tank with secondary pilings.
When the new pilings are taking part of the load, individually dig under the existing pilings & pour conic footings (may have to do just a few at a time as the secondary pilings will only take a percentage of the load). Then (if he still wants or needs it) pour a slab.
Dennis

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