Underground storage structures...

I promised one of the wonderful Monkey Mods that I would try to post a real prep oriented thread as penance for shamelessly hijacking one on Wednesday...this is what I could think of that might contribute to discussion.

One of the things that hasn’t been talked about much (at least in recent memory) is storage of preps…specifically underground storage.

There are various options for underground storage, starting with old school root cellars and continuing through state of the art multi room blast and fallout shelters with all the bells and whistles.

One that I was introduced to when I was first starting to build our BOL/Retirement Home was extra septic tanks. Septic tanks come in a variety of sizes and, especially in recent years, materials from concrete to reinforced fiberglass. I should mention that my introduction to them around the fire with local guys I had working with my on our land grew out the propensity in my neighborhood at the time for illegal marijuana growing operations. At one point it was estimated that something like 75% of the decent sized pieces of land on my road at the time had been paid for with the proceeds of high quality pot grows. Though I was a federal LEO at the time, my job was only apprehension people with federal warrants and not investigations of federal crimes. A few of the guys knew what I did for a living, but they also knew that I had no love for laws that were not my responsibility to investigate, AND (IMO) not only counterproductive but unconstitutional. (though nobody ever offered to show me their underground grow operation). I ended up using another method, but the extra work and degradation over 30 some years have made me often wish I had gone the septic route.

Septic tanks, depending upon capacity tend to have interior dimensions at least 8 ft high in the center and start at around 12 ft wide and 16 ft long. They tend to be sort of a bowl at the bottom rather than flat, but even the small ones can be flattened with lumber put in crosswise and still have around 6 ft “ceilings”. They can also be “strung together” using culvert pipe as passageways. They are better than shipping containers because they are designed to be buried and require no additional strengthening, unlike shipping containers that are strong only at the edges and require significant work to spread the weight of soil both on top and pressing against the sides. It is smart to use “clean” dirt next to the tank (especially the newer lighter weight reinforced fiberglass tanks) because sharp rocks with weight behind them can otherwise ruin one’s whole day. It is also easier to have a septic tank delivered to a hole in the ground without raising questions in the mind of the person doing the delivery.

One other caveat is that no matter what kind of underground structure you use, it will not be safe from a government agency with a strong suspicion that you may have contraband (for those who might consider burying their guns against a possible ban), but one can expect that the average thief/looter will not have the advantage of arial infrared imaging or ground penetrating radar/anomaly detectors.

What other underground structures might others that you monkeys know (since I won’t ask what you may use any more than I will tell what I might use) that would be a good option?

 

Used and cleaned Gas Station Fuel Tanks.

Dual wall fiberglass buried on their sides.

I had a design I did for one that would also be a Tornado Shelter.

But long gone on a older Cad Computer.

Dig the hole, back fill with sand, cover top with sand in an arch, cover with 6 inches of cement, cover with 2 feet of soil after cement cures.

Add an extra tank and camo the entrance and you could have secure storage or "other".

 

Hmmm. I'm not sure that any tank that held gasoline can ever really be "clean" afterwards. I know of an instance where an old above-ground gasoline tank had been emptied, abandoned and left open to the elements for more than fifteen years. It looked clean and smelled clean when you went inside it. The owner hired a guy to cut it up for scrap. As he was cutting, the heat of the torch apparently drove gasoline fumes out of the surface of the old rusty metal. Once they reached the right proportion, the tank blew up, killing the welder. Fiberglass might be different. IDK. With a new tank, though, I'd say great idea!

A person might start a business, using new tanks, because the demand for underground shelters.storage is high right now, and the numbers might be very advantageous.

 

EPA approved and already done here because all single wall tanks had to be replaced.

Many were converted to DEER stands, animal shelters, and other storage.

 

I was wondering about burying shipping containers. I always questioned how deep they could be buried and it they were able to hold the weight of earth over time.

Interesting idea using a septic tank. Like it @PaxMentis

 

When I was very young (yes, they had gasoline then) my uncle was welding a repair inside a supposedly clean crude oil tank and set off an explosion that killed him....that was in the '50s though and neither cleaning agents or OSHA regs were near what they are now.

 

Local concrete co here in NH builds well houses that are buried to keep from freezing. Will make almost any size you want to pay for. They also make large tanks used for water supply for fire sprinkler system. A sub division near me put in 2 separate 40,000 gal ones. They also make large 2 piece septic tanks and you can get 2 tops and leave out the bafffles. The sky and your pocket book are the limit, that and the local granite ledge that may even prevent a good sized fox hole.

 

Shipping containers make bad underground storage areas, they are constructed to take the weight of the container above it, and not dirt pressing in from the sides and top.
People ask this question all the time and unless you reinforce it with concrete and re-bar they will collapse, and it's cheaper to build a block building instead.

Rancher

 

Thanks @azrancher . I also heard that the shipping containers are toxic or some of them are. I see all these people making houses in them but you have to do certain steps to seal it or something. I have to go find that info again.

 

Actually, it is much easier and less expensive (especially if you have timber on the property...probably a rare option in AZ) to use logs the length of the container to spread the weight and brace against the "frame" of the container. However, a friend who did this around the same time I was building now has rust spots coming through...after a mere 30 odd years...who'da thunk?

 

Beware, even concrete tanks can float. Yes, floating can happen in sandy soil with a high water table but it can also happen in heavy clay if the hole fills with water. So, if a tank will not be filled with water, you need to bury it deep enough that the weight of the tank plus the weight of the dirt on top exceeds the gallon capacity of the tank times 8 pounds per gallon. So a 1000 gallon fiberglass tank that weighs 400 pounds needs 7600 pounds of dirt on top of it. (this is a conservative calculation but if you factor in the shear strength of the soil it can be reduced, but sandy soil has very low shear strength so the above covers worst case.) As you may guess wider, flatter tanks have more area on top so need not be planted as deep to get the necessary weight on top of it to prevent floating.

Many septic tanks being used in the mid-west now are polyethylene plastic. Most of the 1000 and 1500 gallon tanks I've seen in both plastic and concrete at building suppliers in last few years were only 4 to 4 1/2 feet tall. It can be more expensive to set a taller tank because the hole depth and boom height to lift the tank can be beyond the capabilities of a typical backhoe and excavators are often needed and much more expensive to bring in for the job.

AT

 

Some of what you mention was considered in my decision to go with a round (horizontal placement) tank.

Also the reason I suggest 6 inches of concrete and a top fill of two feet of native soil.

Also it is best if you have a hill to burrow into. This allows drainage from rain as well as a way to have a septic system for the tank. This allows a less complicated way of digging the hole and placement of the tank. Given time and a good diesel tractor, with a heavy duty box blade, will do the trick. Then a front end loader can replace the soil.

OPSEC all the way.

Underground construction should not be taken lightly.

 

Good idea going in hillside. If you build on or in a hill, you can also run footer drains to daylight and eliminate the issue of floating.

 

Interesting.

I'm quite intrigued with the idea of underground storage, both for OPSEC and for keeping preserved foodstuffs and ammunition in a stable temperature environment for effective long term. Being well hidden in combination with a good heavy steel door it should discourage most common pillaging.

It could also act as an exterior "safe room", a place to retreat that would be difficult for perps to find or penetrate even if it is found. Even better would be to have an alternate means of escape, a second well hidden exit.

If using a concrete septic tank buried in the side of a hill, could one cut an entrance hole in the side of the tank for a door using a concrete saw? Could such a void weaken the tank structurally to the point where safety would be an issue?

 

If you look at the "old" root cellars in NH, most were built in a trench cut into the side of a hill with "french" drains to keep the water level below the floor. If you are digging by hand or with a bucket loader, it is much easier to dig into a hill, you are on the same level, than to dig a hole and lift all the dirt. My biggest regret is that 30 years ago I didn't plant black walnuts, butternuts, apple and fruit trees and such. I didn't plan ahead enough and get my greenhouse etc. At the time I bought a 4 wheel drive snowplow pickup that I needed instead. It was junked 15 years ago. Another regret is not doing it right the first time. When I built my tractor shed, I did not put in a good concrete foundation and floor. I have replaced the "pressure treated" sills twice and the building is 6 inches out of level and it is a total pain to use a jack or work on equipment. I am 77 and my clock is running out, but those of us who are younger might take care to prevent that "for now" project becoming something you put up with for 30 years. If things do fall apart you will not be able to replace those parts that were good enough for now or redo correctly. Guess I would rather have one good Collins axe that holds an edge, bought in an antique store, than 10 China mart axes that almost work. I have a room in the basement with a dirt floor and I use that as a root cellar. Keeps potatoes etc, handy to get to, snow doesn't have to be dug out, and OPSEC isn't to bad. Guess that the lesson I have learned was that I would prefer a well built small multi purpose shelter now, to either no shelter as I can't afford a big one, or a large half a**ed one that either doesn't really work or requires constant upkeep. The second thing I have learned is that time goes by so fast that putting things off does not work. My wife and I don't smoke or drink. don't care to, but in the last nearly 60 years, the money we did not spend has added up to enough to buy a home. That a small investment made each day, towards a garden, good roto tiller, greenhouse, good chainsaw, etc just keeps on saving money now and may save you and your loved ones lives tomorrow.

Love to read one of the most thought provoking threads here. What did you put away today? How often do you say I never thought of that.

 

Oh Yeah, I lived in Kalifonia for the first 4 years of my career, LA had real hard rains, mud flowed down into many people's swimming pools, so what do you do with muddy water... you pump it out. Swimming pools float, and they make boats out of concrete also...

Rancher

 

Just to mention...concrete tanks could conceivably float.

That said, my area is right on a river that floods every 10 yrs or so to the point where most of these of which I am aware could be partially underwater. We have a highly clayey soil with a goodly amount of rock and sand...I have yet to hear of one doing so. Even the "plastic" 8' tall 24' diameter round holding tank (neither room nor base able to pass a perc test so we must have it pumped out every 5 yrs or so) at the little house in town, which has been underwater 3 times since my son bought the house, has shown any signs of buoyancy.

As always...YMMV

 

Not too late, a small well insulated dome will serve you well.

No doubt, the day I left the Mil was the day I stopped drinking and I never did smoke. The amount you save can make a big impact on your life and your health.

I always suggest you build small but plan for big. In this, for us, it was a core building for the shop. Designed to be expanded and set up for small expansions as time and money permit.
This meant slab, heavy duty double wall construction with king post roof truss of 3" x 5" angle iron.

Most of the building material was salvaged from an economic downturn. The building and land was developed with a plan and no dead line to cause me to hurry.

Many helped with suggestions and at times labor or equipment.

In the process I purchased a large capacity Rod Hot Box that is still in use and allowed me to weld solid and proper seams.

 

@HK_User can you elaborate on the 'small well insulated dome'? Did you have something specific in mind?