How To Install a Big Water Storage Tank Partially Underground…and Why It’s Worth Doing

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In September of 2013, understanding the why of it, we figured out how to install a big 2825 gallon Bushman water storage tank partially underground, in hybrid fashion, with two feet of the tank underground and the remaining five and half feet of height above the surface. These tanks are designed to catch and hold rainwater, but that’s not what this one is doing.

In fact, though we do live off grid, we don’t bother with rainwater catchment at all. Our home’s roof doesn’t even have gutters.

Instead, this tank is now serving as a batch storage tank for our well water. Pumped up some 325 feet from the aquifer, the water runs a circuitous route through our property (long story) to reach the homesite, traveling nearly half a mile in the process. It’s not a difficult task, just a matter of firing up the generator stationed at the wellhead and plugging in the well pump.

The system delivers enough water through one inch piping to fill our old 500 gallon tank in twenty minutes or so.

However, that older tank had its exposed supply and outlet pipes burst dramatically in single digit weather in 2011, with a lesser bit of damage in slightly warmer weather last year. We could finally afford to upgrade things a bit…so why not get as big a tank as possible and install it partially underground?

Doing it that way would provide a number of benefits:

    1. With the outlet pipe to the booster pump installed completely underground, that line would never freeze. Even in the Big Freeze of 2011, nothing froze below the surface of the Earth.

    2. The inlet pipe could be plumbed with an underground drain valve, opened after every tank fill in colder weather. This would protect the supply side of things as well.

    3. Being set even a couple of feet into the soil, sort of like a giant fence post, the big Bushman tank could laugh at the wind. The tank on the tower has to be lashed down, at least when it’s empty or nearly empty, but the big beast on/in the ground won’t be going anywhere.

    4. No more ladder climbing to check the water level in the tank. I can stand on the ground next to the tank and peer right down in there.

    5. Being mostly above ground, we’ll still have gravity feed water available if the booster pump fails. Only a trickle, to be sure, but anyone who’s ever lived rough knows that, compared to nothing at all, a trickle can be a real lifesaver.

    6. Size, of course. A 500 gallon tank full of water usually lasted us at least a week, often ten days, and not infrequently as much as two weeks. Still, Pam worried constantly about the water being low. She’s a worrier, my redhead is. Now, with the 2825 gallon tank in place, I can simply schedule monthly fills and know we’ll never run short.

Why did we go with the Bushman? After all, there’s no such thing (that we’ve been able to find online, anyway) as a tank designed for hybrid underground/above ground installation as we’ve done here. There are surface tanks (of which the Bushman is one) with built-in resistance to UV damage from the rays of the sun. There are underground tanks built strongly enough to withstand the pressures of being buried. But they’re never both; the underground tanks have no UV protection (moles don’t need that), and surface tanks aren’t built strongly enough to bury safely.

The Bushman, however, does appear to be built more sturdily than most surface tanks. The ribbed wall design looks pretty strong…so that was our choice. Since the water level in the tank would seldom if ever drop below surface level anyway, it should work.

Our 2825 gallon Bushman water storage tank, being installed in "hybrid" fashion, with the bottom two feet of height buried and the rest above ground.

Our 2825 gallon Bushman water storage tank, being installed in “hybrid” fashion, with the bottom two feet of height buried and the rest above ground.

The day after deciding on the Bushman tank, I drove to town for groceries and noticed a whole bunch of the exact 2825 gallon version we wanted, sitting right there in a dealer’s storage yard.

We’d had no idea there was a Bushman dealer in the area. Not only that, but he delivered the tank, towing his trailer right on across the one lane Stoner Trail, just a bit of packed earth filling in the road that had washed out during a flash flood in July. No commercial freighter would attempt that route, and the seller didn’t even charge any freight to get it here.

Wow. I do love it when a plan comes together.

Note: This tank cost under $1500, delivered.

The next step was getting out the Ryobi brush cutter and whacking the weeds in the area chosen to be the tank’s new home. The vegetation was high, thick, and rank, plenty of it…and still in chigger season, too.

With the site chosen for the new water tank cleared of vegetation, it's time to bring in the backhoe.

With the site chosen for the new water tank cleared of vegetation, it’s time to bring in the backhoe.

Then it was time to call our friend, Robert Stoner. He brought over his backhoe, threading through the mesquite trees and other bits of brush out back, maneuvering to reach the tank site without doing any more damage to the terrain than necessary.

Which was pretty impressive, the way he did it. There wasn’t any damage en route.

Robert Stoner tiptoes his backhoe through the mesquite, doing no damage whatsoever.

Robert Stoner tiptoes his backhoe through the mesquite, doing no damage whatsoever.

I’d staked out the area I wanted dug, roughly twelve feet square. Robert set up and went to work, finishing the excavation in under an hour. The man knows what he’s doing with that backhoe…and he’s a neighbor, just a mile up the road, which is handy and then some.

The backhoe stretches out and prepares to dig.

The backhoe stretches out and prepares to dig.

Yum!  That first bite of dirt is delicious!

Yum! That first bite of dirt is delicious!

Robert defines the excavation on the far side, then the near side...

Robert defines the excavation on the far side, then the near side…

...then down the middle.

…then down the middle.

And...done!

And…done!

October 19, 2013. The project sat idle for nearly a month while a computer brushfire took priority. For weeks, I slept very little, glued to the screen, migrating away from another site (where I’d written for years) to this one.

By the time that migration was finished, so for the most part were the chiggers, which was a good thing.

After digging down with a #2 shovel (carefully!) to expose the existing water pipes, a ten foot trench was extended from the lines to the excavation. After that, using a ten foot 2″ x 4″ board, a level, a shovel, and a hoe, the bottom center of the square hole was leveled as closely as possible.

I’d considered either (a) pouring a concrete pad in the bottom of the hole or (b) building a low deck of treated timbers…but in the end, that made no sense. The high clay content earth in the excavation floor is mighty solid stuff, liberally spiced with caliche (limestone rock). Even a full tank was unlikely to settle much.

Even if it did settle a little, there was no huge rush. The incoming piping could be plumbed, the tank filled to capacity, and the whole thing left to its own devices for a few days. That should stabilize things sufficiently, after which the outgoing piping could be added and the giant “post hole” filled back in to surface level.

With that decided, Robert brought his backhoe over one more time, strapped the tank, lifted and carried it delicately from the front yard around through the mesquite, and deposited it gently in the hole.

This Bushman tank came with two pre-plumbed outlets, both with one inch plugs screwed down but not too tightly. We wouldn’t be using the one on the back side, so that got removed, wound with Teflon tape, and replaced–tightly.

On the front side, the plug was removed and discarded, replaced by one inch outlet PVC piping. For the moment, only enough PVC has been added to allow the inclusion of a ball valve, so that the valve can be closed while the tank is filled for testing and settling purposes.

Yesterday, a twelve foot wooden post, constructed by lag bolting two 4″ x 6″ treated timbers together in an L shape, was planted in a post hole near the tank’s 4″ top opening. The post will support incoming PVC, allowing the pipe to pour well water freely down into the tank’s screened top hole (when the plastic debris-stopper lid is removed).

Then it was time to start the inlet piping run.

The post on the left of the tank will support the incoming vertical PVC pipe run.  The pipe will go up and over the post, then down to point free-falling water into the tank (when the little yellow lid is removed).

The post on the left of the tank will support the incoming vertical PVC pipe run. The pipe will go up and over the post, then down to point free-falling water into the tank (when the little yellow lid is removed).

The old incoming pipe, supplying the old 500 gallon tank, has been cut to allow inclusion of the 2825 gallon Bushman tank in the system.

The old incoming pipe, supplying the old 500 gallon tank, has been cut to allow inclusion of the 2825 gallon Bushman tank in the system.

The ball valve (red handle) can isolate the older 500 gallon tank.

The ball valve (red handle) can isolate the older 500 gallon tank.

The valve to the left (mid-trench) can isolate the new 2825 gallon Bushman tank.  Note:  all underground valves will have "sprinkler valve" type shafts protecting them from surrounding dirt; they will not be buried.)

The valve to the left (mid-trench) can isolate the new 2825 gallon Bushman tank. Note: all underground valves will have “sprinkler valve” type shafts protecting them from surrounding dirt; they will not be buried.)

Hooking the incoming line 45 degrees to the left, to begin quartering around the tank toward the support post.

Hooking the incoming line 45 degrees to the left, to begin quartering around the tank toward the support post.

The drain valve (far left, to the left side) will be used during the winter months to clear all water from above ground piping.

The drain valve (far left, to the left side) will be used during the winter months to clear all water from above ground piping.

At that point (above photo), the sun had set. The days are definitely getting shorter as we move toward November.

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October 25, 2013. Today, I got the incoming water pipe (from the wellhead) run up the support post next to the big water tank. From the top, the 1″ PVC continues over and then down toward the 4″ fill hole in the top of the tank. However, that bit of piping had presented a worrisome possibility: What if, over time, the weight of the pipe itself caused the water-drop pipe to bend until the outflowing water, intended to go into the tank, ended up splashing on the tank? That would not be good.

To guarantee that would never become a problem, the last vertical pipe drop (aimed at the tank fill hole) was constructed with a free-sliding sleeve some 12 inches or so in length. The sleeve is simply a piece of 1 1/2″ PVC with threaded couplings added to both ends. Fortuitously, those parts (pipe and fittings) were sitting around on hand, doing nothing, just waiting for a chance to be of use.

Between fills, the sleeve sits on the edge of the fill hole rim, close to the yellow debris-stopper cap. During fills, the cap is removed and the collar “locks” inside the edge of the fill hole. Not a drop of water is spilled this way, and the transition between pipe positions takes mere seconds to accomplish.

The free-sliding collar, assembled and ready to install on the water fill pipe.

The free-sliding collar, assembled and ready to install on the water fill pipe.

Sliding collar resting near the edge of the fill hole before the first fill.

Sliding collar resting near the edge of the fill hole before the first fill.

Moving the collar into position to fill the tank.

Moving the collar into position to fill the tank.

The wellhead pump is now running and filling the tank.

The wellhead pump is now running and filling the tank.

Once the tank filled to overflow–which took far less time than we’d expected–I heaved a sigh of relief. No matter what the wind might do now, the big water storage unit wouldn’t be shifting anywhere. Not even downward; that clay/caliche combo is some serious stuff.

However, one part of the system worked almost too well. The drain valve for the inlet pipe turned out to be low enough in elevation (roughly two feet lower than the old tank’s above ground drain outlet) that it allowed a whole lot of piping between the wellhead and the tank excavation to empty out. That’s great antifreeze protection, but it looked like 50 gallons or so of water down there.

An abundance of control valves were being included in the new two tank system, which would give us the ability to easily isolate either tank. Everything was looking good…but for this particular drain valve, we needed better drainage.

The drain valve allowed a lot of inlet piping to empty out.  We needed better drainage.

The drain valve allowed a lot of inlet piping to empty out. We needed better drainage.

An abundance of control valves will allow us to isolate (and/or drain) either tank.  In this photo, the upper valve controls incoming water to the big Bushman tank; the lower valve  controls water outflow from the tank to the booster pump.

An abundance of control valves will allow us to isolate (and/or drain) either tank. In this photo, the upper valve controls incoming water to the big Bushman tank; the lower valve controls water outflow from the tank to the booster pump.

To provide a small drainfield for that main tank’s drain valve, an oblong hole (because of the restricted area between the excavation wall and the piping run) was dug some two feet deep and filled with large gravel rocks. Hopefully, that will be enough to handle the inlet pipe drainage during the winter months.

At any rate, it’s a lot better than nothing, which was what we had prior to digging the hole. The clay/caliche soil is next thing to impervious in that area and will hold water for days on end if left to its own devices.

This hole was dug and then filled with large gravel rocks to provide a small drainfield for the drain valve's outflow.

This hole was dug and then filled with large gravel rocks to provide a small drainfield for the drain valve’s outflow.

October 30, 2013. The area around the new tank could finally be filled in with dirt. First, each valve in the line was provided with a “tower” to keep it from being buried and put out of commission. The key element in such a tower is the largest round “irrigation sprinkler valve” cover available in the big box home improvement stores. However, none of those black plastic beasts with the green tops are tall enough to do the job by themselves.

To provide the needed extra tower height, a cheap plastic five gallon bucket is pressed into service.

The best of these are old paint buckets or buckets that once held hydraulic fluid–anything that came from the store with “stuff in it”. They’re a lot stronger than the sorry pieces of pail sold separately by Home Depot or Lowe’s for a couple of bucks each.

Still, any bucket will do in a pinch. I ended up using five different bucket types, no two of which were equal in strength.

Building a valve protection tower involves the following steps:

    1. Saw off the bottom of the bucket with a small handsaw.

    2. Saw the necessary notches in the top edges of the bucket to allow the “open cone” to fit upside down over the pipes in the trench.

    3. Shovel in enough dirt to (a) stabilize the upside down bucket and (b) provide support for an irrigation control valve cover.

    4. Set an irrigation control valve cover in place. I leave three inches (or so) of the cover jutting above the surface, which is not the way the pros do it–but it works a lot better for our application. Ground level cover installations (as done by lawn pros everywhere) just beg to be filled full of mud and dirt when the monsoon rains come.

    5. Fill in around the tower with dirt and…done.

A valve protection tower.  This one is a "three stacker" due to the valve's considerable depth.  First, there's a gray bucket (cut to fit) on the bottom, topped by a blue and white bucket, topped by a commercial irrigation sprinkler valve cover.

A valve protection tower. This one is a “three stacker” due to the valve’s considerable depth. First, there’s a gray bucket (cut to fit) on the bottom, topped by a blue and white bucket, topped by a commercial irrigation sprinkler valve cover.

There was still a good bit of pipe work to do in the trenches away from the new tank, but the main excavation could be filled in now. By the end of the day, much of the area around the tank had been brought back to surface grade, with the completion of that portion of the project finishing up the next afternoon.

What? Oh, no, I didn’t call Robert to bring his backhoe over for the backfill work. That was done with a #2 shovel, a wheelbarrow here and there, and carrying five gallon buckets of dirt to dump as needed.

By the end of the day, most of the area around the tank had been brought back up to surface grade.

By the end of the day, most of the area around the tank had been brought back up to surface grade.

November 2, 2013. We used up the remaining water in the smaller (500 gallon) tank atop the water tower, drained that, and switched over to the big tank. All of that went off without a hitch except that there was a lot of air in the lines for a while, which meant the booster pump couldn’t keep its prime. It kept shutting off prematurely.

That problem was solved by running the cold water faucets in the house for about 15 minutes. After that, the pump worked just fine.

Now there was just one aspect of the overall project that remained. With the gravity feed tank decommissioned for now, the laundry room water line had to be pressurized. Prior to this, the washer had always run off mere gravity feed. Pressurizing the line should make a big difference in the machine’s operation…but first, I needed to shut a few valves, pull the plug on the booster pump, open a few faucets, and get rid of the pressure in the house line. After that, the usually pressurized house line would be cut open and a connecting line inserted to run through a short trench, hooking into the laundry shed line.

To make this workable, the old gravity feed supply line was simply cut off and capped.

When I made the turn around the pump shed with handsaw in hand, the little Mojave green rattlesnake’s coil immediately got my attention. Had I not noticed it (highly unlikely), I’d have ended up bending over to cut the line in the trench with my right arm and shoulder within inches of the snake’s spade shaped, ultra venomous head.

I lost a little time taking pictures of the snake, blasting it with my Dad’s old .410 shotgun, and then digging out under the pump shed to make sure there were no more reptilian threats lying in wait under there…but that was time well spent. Better that than a whole lot of time in the ER at the hospital or, alternatively, at Hatfield’s Funeral Home.

This young Mojave green rattlesnake was in a resting coil behind our pump shed at approximately 3:00 p.m. on November 2, 2013.

This young Mojave green rattlesnake was in a resting coil behind our pump shed at approximately 3:00 p.m. on November 2, 2013.

When the 18 inch Mojave green rattlesnake was in its resting coil, before that area was shoveled out a bit, failing to notice the snake (Not likely!) would have put me in mortal danger.

When the 18 inch Mojave green rattlesnake was in its resting coil, before that area was shoveled out a bit, failing to notice the snake (Not likely!) would have put me in mortal danger.

With the snake issue put to rest, I had to hustle. I hadn’t even gone outside to start work till 3:00 p.m. or so; I was burning daylight.

With the necessary connections made, it was a matter of waiting an hour for the PVC glue to set before turning the booster pump back on. In the meantime, there were more connections to make. I called it quits when I could no longer see the ground clearly enough to be sure I wasn’t stepping on a snake. The house water powered up just fine, no leaks, good to go.

November 3, 2013. The standing spigot (an offshoot of the laundry shed line) was added today and strapped firmly to the water tower wall. Several more valve protection towers were assembled and installed. The trenches were finally filled in…and all that was left to do was to haul loads of gravel over from the pile by the house, constructing walkways that look good and really, really help when the monsoon rains come drenching down.

Valve covers, valve covers, valve covers everywhere!

Valve covers, valve covers, valve covers everywhere!

Downhole in the "blue tower".  These valves (a) isolate and (b) drain the outflow pipe from the currently retired 500 gallon gravity feed tank.

Downhole in the “blue tower”. These valves (a) isolate and (b) drain the outflow pipe from the currently retired 500 gallon gravity feed tank.

Downhole in the "orange tower".  Situated within inches of the blue tower, this shutoff valve prevents the older 500 gallon water tank from being refilled, at least for now.

Downhole in the “orange tower”. Situated within inches of the blue tower, this shutoff valve prevents the older 500 gallon water tank from being refilled, at least for now.

The gravel walkway around the newly installed 2825 gallon Bushman water storage tank.  Two feet of the tank's total height (a bit more than a quarter of the total) is buried, providing a low profile, wind resistance, and protection against frozen water pipes.

The gravel walkway around the newly installed 2825 gallon Bushman water storage tank. Two feet of the tank’s total height (a bit more than a quarter of the total) is buried, providing a low profile, wind resistance, and protection against frozen water pipes.

As happens with many of my building projects, this one has been a bit of a journey…but well worth it. Now there’s only one real remaining danger point when it comes to subfreezing temperatures at the Border Fort, and that project is next.

6 thoughts on “How To Install a Big Water Storage Tank Partially Underground…and Why It’s Worth Doing

  1. Ghost, does this tank supply water for all the plumbing in the Border Fort? What’s the tank made of? If it’s plastic, is it BPA free?

    You amaze me. You’re a modern day pioneer!

  2. Sha,

    1. Yes, it does supply water for all of the Border Fort plumbing.

    2. Yes, it is plastic and it is BPA free. I didn’t even think about that when choosing the tank, nor does Bushman comment on BPA one way or the other. However, the literature does state that these tanks are made of polyethylene (presumably high density polyethylene), which does not contain BPA.

    Thanks for the amazement. Oddly enough, It really doesn’t strike me as though what I do should be all that impressive. Rather, most of “normal” society leaves me scratching my head a bit.

    I suppose it’s always been like that, though. In the 1800’s, no doubt the city folks back East considered the original pioneers to be out of their minds–and the pioneers thought the mountain men were going too far, living entirely alone in hostile territory as they often did. Reckon it’s all in your perspective. 🙂

  3. Interesting article. I was wondering how that thing handled the outgoing air when you filled it and then I saw the picture that explained it. Love it when you answer my questions every time. I missed this when you wrote it, I had a trip to the VA and have been really busy. We have another trip to the VA tomorrow and then that should be it for this month.

  4. Hm. I knew I should have added one more photo (which I could always do, of course). There’s another (four inch) way for air to escape, namely a screened overflow vent on the back side of the tank. It prevents a complete fill, but we don’t need that with this much total capacity. The bottom exit point on the overflow is 9 inches below the tiptop of the thing (out of 90 inches total, so it gets 81 one inches of water).

    I think the fact that I won’t need to climb any more ladders to check or fill a tank is making Pam happier than the gallonage. Despite the fact I’m an experienced monkey (aka oil patch workover rig derrick hand, water hauler, etc.), she still figures I’ll either get too cocky or too senile some day and make a mistake, so…:)

    The VA trips have got to be tiring, for sure. I remember when my Dad broke his back (ruptured a disc) in 1961 and had to have his spine fused at the VA (Fort Harrison, west of Helena, MT–where part of The Dirty Dozen was filmed). We only had a half ton pickup, other than the 2 ton stock truck, so a neighbor loaned me his Plymouth station wagon to haul the old man back home when they let him out of the hospital. It had one of those TorqueFlite push button automatic transmissions, shifted pretty smoothly, but even the slightest jiggle in the road was enough to spike Dad’s pain in his full body cast & set him to muttering about my driving.

    He was never the same after that, and that happened when he was 37 years old. I was 17 at the time.

  5. Those VA trips are totally exhausting. I usually drive anymore, he is getting to the point that his reactions are not fast enough in that traffic. He is aging so fast anymore. He is only 65 and acts like he is 85 most times. I am not used to driving in traffic like that and so I get totally tense, which wears you out, especially after pushing someone around the VA in a wheelchair all day.
    Only one appointment yesterday and three tomorrow. First one is at 11:30, and then 1 and 2. We might be home by 5, but since we usually stop for something to eat on the way home, who knows. We will eat before we go, but have to stop somewhere after we get out of there. Might go to the cafeteria for lunch, since we will have a long wait between appts. They make some really fine subs there. Lots of meat and vegs for not too much.

  6. I know exactly what you mean about exhausting driving in serious traffic. I always have to seriously cowboy up for jaunts like that. When I was trucking long haul, I got turned around, more or less lost, just about very time I had to make a run in to the company terminal in Elizabeth, New Jersey. The trickiest part of that is there are quite a few roads in that area that are closed to big rigs; getting caught on one towing a 53′ dry van would not have fun results.

    Most recently, of course, was my late July / early August run to Los Angeles for DreamCon. I was mighty glad that the rental car I was driving, while undersized and not exactly comfortable for the long miles, was clearly geared for the city. Step down on it and that little beast would zip in and out of tight spots in a hurry.

    I never drove once I got there, though, either hiked to the meetings and back or took the hotel shuttle van. Had to go in (not knowing the area at all) right smack in the middle of a workday but managed to time my exit for late enough on a weekend night that there wasn’t much traffic at all.

    Still didn’t completely relax till I was all the way back out of California, though. Lived in San Diego County for 4 years once (late ’80’s), but La La Land still gives me the heebie jeebies.

    Really fine subs sound helpful. Especially with Dennis having diabetes, I don’t reckon going too long between meals is a spiffy idea….

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