I’ve been considering the idea of deepening the garage foundation on my next home to allow for one or two cisterns. One wall would adjoin the basement. Any reason why this would be a code problem?
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Replies
Not sure just where or what you are are placing for a cistern but be aware that engineering wise there are constraints.
The "Load " of the water and cistern combined will be considered to be spread down and away from the bottom of the cistern at a 45 deg. angle.
Any structure in that area will have to be constructed to withstand the lateral loads placed on it.
Sketch out your plan in elevation and draw a 45 deg. angle from the tank down and away. If you have the basement wall/footing falling within that line you have problems.
The cistern water is for lawns and gardens. The plan is to collect from the roof and possibly the driveway.
I've built forms for similar sized standing tanks at new sewage treatment plants so I'm acquainted with the basic requirements. I've also built various types of vinyl liner pools so I'm aware of that option. In fact it may work out that a big round above ground, placed under a deck with a cover on it, would be the simpliest and most economical means to my requirements.
Any reason why this would be a code problem?
Depends on whether your AHJ's code covers storage of what would probably be listed as non-potable water.
After that, it's a support issue, water is 62-63#/cf, or around 7-8#/gallon. 1200 gallon storage tank will hold 4-5 tons of water. When I was "doing" houses around Austin, rainwater collection is a pretty big deal. My rule-of-thumb cipher was to figure on a 500 gallon bladder running about 2 tons, all-up, full; and then see where the engineer went with those sorts of numbers.
I generally found it a bit easier, at least in those temperate climes, to create storage under decks & patios, at the lowest possible site location. Now, most of those sites also were on rock, with only 12-24" of topsoil, so excavated sites were, budgetarily, out of the question. Mostly.
Oh, and you definitely want to check with the plumbing inspector in your AHJ, as irrigation water (an excellent use for conserved rainwater) can require some "proof positive" (read obvious to Public Employees) plumbing connections that cannot mix your stored water with the potable water supply. (Like a visible-from-street filler pipe connected to float-driven pump dropping water, visibly, 24" into the rainwater collection system <what a pain>.)
<<I generally found it a bit easier, at least in those temperate climes, to create storage under decks & patios, at the lowest possible site location. Now, most of those sites also were on rock, with only 12-24" of topsoil, so excavated sites were, budgetarily, out of the question. Mostly.>>
So what did you use for storage? I assume it was round. I've considered corrogated galv. steel tanks, the kind that are usually seen in cattle country, next to a windmill driven pump. I don't know much about them. For example, can they be bolted to a concrete slab and sealed around the bottom?
Any of those plastic tanks worth a look? Or are they limited in size? I'm starting at a minimum of 10,000 gals. That's barely enough to keep lawns and gardens alive during a dry spell so I prefer to have double or triple that capacity.
I'm starting at a minimum of 10,000 gals. That's barely enough to keep lawns and gardens alive during a dry spell so I prefer to have double or triple that capacity.
10000 gallons is an enormous tank-think really big gasoline tanker truck. Why do you think you need so much, given where you live?
I suspect a pond would be cheaper if you have the room.
<<10000 gallons is an enormous tank-think really big gasoline tanker truck. Why do you think you need so much, given where you live?>>
Yeah, I'm already pretty well acquainted with the sizes of tanks, etc. And 10,000 gals isn't going to be enough to irrigate both lawns and gardens, not during a hot dry summer.
Imagine a country home on five acres with 300' of road frontage, set back 100' from the road. Front lawn is about 100'X200'. Then figure about 50' of lawn around the sides and back of the place. Now we're talking about 30,000 sq ft. of lawn, plus a fair sized vegetable garden and some flowers.
You can get a better idea of the requirements by reading this:
http://www.greenbuilder.com/sourcebook/RainwaterGuide2.html
Edited 3/27/2007 12:35 pm ET by Hudson Valley Carpenter
Now we're talking about 30,000 sq ft. of lawn, plus a fair sized vegetable garden and some flowers
My lawn and garden areas are probably a little larger, but in the summer, the lawn gets what mother nature provides. We're in Maine, about 45 inches of precipitation per year with frequent dry spells in the summer. We water the big vegetable garden (about 50x70) by pumping water out of the pond/swimming hole. The system you'll need for the occasional drought year will cost more than you'd spend flying to France for your vegetables.
<<My lawn and garden areas are probably a little larger, but in the summer, the lawn gets what mother nature provides. >>
That's one approach, certainly, the one that most people have come to accept. But I'd much prefer not to watch my lawns burn out in August after tending them for a several months, not if I can help it. That's what happens all too often in the area where I'll be building. Eastern slope, lots of sun.
It would be great if I could put in a pond and I may do that, down in the bottom of my property, near where I intend to put the vegetable garden. But soil conditions may not allow it and even if that works out, there's way too much difference in elevation to pump the water back up to where the lawns are. Running power five hundred feet to operate a pump for the garden may not make a lot of sense either. That's a primary reason why I prefer to collect and hold the water at the higher elevation. Irrigating the garden by gravity has always been the preferred method, just because it's then a source of food which isn't dependent on anything outside.
i'll run in a completely different direction.do you do much with the lawn?
football with the kids or neighbors, or mostly just mow it?if it is a low traffic lawn you could replant to a fine fescue,
which is drought tolerant and slow growing.
less watering and less mowing.i like the cisterns for the garden though.
espalier
Edited 3/27/2007 4:33 pm ET by espalier
So what did you use for storage?
Well, at the time, I managed to run into a guy who could get 500 gallon triple-ply fuel bladders from the company that was turning them out to milspec. They'd "sit" middling nicely in 27" of clear space, and a I forget how big around just now. So, with a nice slope, you could make a short perimeter wall, and perch a deck over that, and make it a landscape feature.
10 kilogallons is a piece, ah, .1337 * gallons is 1337 cf is a bunch. About 27 square by 2 foot (so, that clearly wants to be multiple tanks. Multiple tanks reduce surface area, which reduces a number of woes with stored water, too.
Now, you might also consider a more drought-tolerant landscape plan, too. Though, around Austin, some of those sites limited lawn by having the storage tanks <g>.
The plastic tanks, from my experience need complete UV protection, and some provision for inspection. Galvanized, above ground tanks are the present "rage" around Austin now (just like they showed the other week on TOH, no less).
If you have room for a wind pump, though, look into a "tower" head tank, too. (If only to give the pump "something to do." Your irrigation system will define what sort of "head" you need; but you could also be "short" on less-breezy days. If you're thinking of off-grid answers, a PV-powered pump might be a good solution, which would also provide "juice" to run a programmed irrigation controller.Occupational hazard of my occupation not being around (sorry Bubba)
<<The plastic tanks, from my experience need complete UV protection, and some provision for inspection. Galvanized, above ground tanks are the present "rage" around Austin now (just like they showed the other week on TOH, no less).
If you have room for a wind pump, though, look into a "tower" head tank, too. (If only to give the pump "something to do." Your irrigation system will define what sort of "head" you need; but you could also be "short" on less-breezy days. If you're thinking of off-grid answers, a PV-powered pump might be a good solution, which would also provide "juice" to run a programmed irrigation controller.>>
Thanks for that UV hint. I hadn't thought about that angle. Funny to hear that folks in cow country could get excited about something that's been around as long as galvy stock tanks. I guess old Austin is getting pretty damned city-fied, huh?
I haven't been watching TOH (took me a minute to figure out the acronym, even) lately but I'll jump over to their website and see what I can learn.
I'll probably use a modest sized pump with a number of zone valves for the sprinklers. I installed a Champion automated sprinker system at my parents home in LA, couple years ago. The controller is mounted inside the back door where it's very easy to operate, on those rare occasions when a change in the program is needed. I'd probably use the same equipment at my country place, just run groups of fewer sprinkers so that a small pump would do the job.
A head tank would have to be too big to be practical.
Thanks for that UV hint. I hadn't thought about that angle.
Well, Austin & Colorado River basin get around 200 days of sunshine a year; if UV will kill it, it's died down there.
Funny to hear that folks in cow country could get excited about something that's been around as long as galvy stock tanks. I guess old Austin is getting pretty damned city-fied, huh?
No, it's like to be the huge growth Austin (Travis & Williamson Counties, particularly) had through the 90s (the number quoted was 1000 per month for new residents in the 2-2.5 county area). While subdivisions popped up like mushrooms, the utilities didn't necessarily follow. In addition, those who could, moved out into the less-developed areas. That area of Texas is a precipitation sincline west of here, they average about 20" of rain annually (vice my 30-35"). Being hillier geography, the rain tends to be convective, and fall in great huge gouts over a short period of time.
Does not take any huge logic leaps to go "hey, if we harvest the rain water, we don't have to buy it in June, July, August, and September to keep the plants green."
Now, open galvanized stock tanks are stock-in-trade as close as a half-hour from Austin in just about any direction. The trick is keeping them filled (many of the aquifers are state regulated).
I haven't been watching TOH (took me a minute to figure out the acronym, even) lately but I'll jump over to their website and see what I can learn.
Yeah, their "winter" project is a "green" remodel in Austin. It's been interesting for me, as I keep seeing some characters I may (or may not) have spent too much time around . . .
A head tank would have to be too big to be practical.
Well, I was actually thinking about a 6'dia. x 8' open top from the windmill man (your climate might mandate a closed top). That'd be 200± gallons, oh, 12-15' up, feeding into the PV-powered pump. Just to make it a tad easier to charge the irrigation lines out at the far edges of the property.Occupational hazard of my occupation not being around (sorry Bubba)
<<Now, open galvanized stock tanks are stock-in-trade as close as a half-hour from Austin in just about any direction. The trick is keeping them filled (many of the aquifers are state regulated).>>
I'd suspect that floating solar pool covers are being used on stock tanks that are meant solely for irrigation. If not, that's a great way to slow evaporation to near nothing. Basically bubblewrap, they are easily affordable.
After checking a bit further, the most economical and probably best all around storage tank seems to be an oval above ground pool. Several reasons jump out at me. First, I doubt that an expensive cistern would be an attractive feature to most home buyers so, no payback. Second, it looks like the concept of using the garage foundation to lessen the cost probably isn't as viable as I'd first imagined. Third, codes and permits for a permanent under ground tank would require engineering, etc., whereas an above ground pool may not even require a permit. A 15'X30" oval above ground will hold the 10,000gals I'm looking for and can be easily hidden under a large deck. Average retail, about $2,000.
probably best all around storage tank seems to be an oval above ground pool
That's an interesting idea, that could be both good and bad.
The bad has two fronts--if it looks like a pool, it can get used like a pool. Using it as a pool means treatment. Treatment means say goodbye to irrigation water. The other "bad" is that it looks like a pool, so insurance will hazard it as an "attractive nusiance." That, then requires fencing and the like.
The good is that it's an inexpensive way to store some depth of water. And store that depth in some quantity, too. Ok, so, it ought to have a cover so as to not evaporae dry (or collect debris that needs screeening from the irrigation system).
Hmm, a fly in the ointment occurs to me. Logically, you want this on the higher slope. Ok, no prob. Except that it sounds like it's higher than the downleaders on the house (maybe). Pumping rainwater uphill during a rainstorm poses some interesting questions, doesn't it?
May take some more cogitation on this.Occupational hazard of my occupation not being around (sorry Bubba)
Installing prior to building the deck, just a foot below the joists, would make it impossible to use as a pool. So no chemicals and no insurance worries. Disassembly would still be possible, just a bit awkward.
The elevation of the pool would be below the lowest collection point, roof or driveway, so no worries about pumping water until it's needed for the lawns.
Installing prior to building the deck, just a foot below the joists
Ah, gotcha.
Deck would "want" access points, I'm thinking, to get to the "Runoff Collection Unit" (to use the fancy terms the CEs put on site plans now-a-days <g>).
Oh, and don't forget a "dump" pipe. That's about 6' of vertical 6-8" pipe on a tee that feeds your storage tank. The first nnn gallons of water, and al lthe debris, bird droppings, etc., will fill that "leg" up from the tee. Once full, the water will "climb" to the fill point on the tank. (Many installations need backflow preventers to stop siphoning, and in peculiar configurations.)
Oh, and if you install the tank in a perimeter wall under a deck, leave scuppers so the tank can drain (or if it springs a leak).
I'm kind of coming back to an idea another poster had, of a pond. Other than the excavation & bedding, the only other real cost would be in the pond liner, and sometimes bigger in liners is cheaper. A pond is also somethign to consider "downstream" of your storage tank for when it's full (it's never leak or be aproblem until the day you have above-average rain . . . <sigh> had to go home and take a shower to get dry . . . )Occupational hazard of my occupation not being around (sorry Bubba)
The five acre site slopes with the difference in elevation, about one hundred and twenty feet. The only viable location for a pond is at the bottom of the property, approximately one acre of flat rich soil where it's anticipated that the vegetable garden will be. Even there, a pond may not be permissible or advisable.
Vegatables can be grown in terraced beds.
I used to have a 10 A spot. The pond ended up being such a cheep addition to the overall plan. Allowed me to move all ove that rich black dirt up higher on the hills for lawns and gardens.
Seriously, price it out. And use some imagination on just how that pond could look.
Terracing the upper elevation, near the house, is planned but I don't want to alter the rest of the property or the old growth areas all that much. Unless my sweatheart develops major organic gardening aspirations, we'll be happy with a simple plot, one which doesn't require major amounts of stored irrigation water.
Even there, a pond may not be permissible
In many rural locations, so-called "farm ponds" can be installed, even though local zoning or land use regulations might seem to preclude them. If you have clay soil (who doesn't in the NE) you don't need a plastic liner.
<<In many rural locations, so-called "farm ponds" can be installed, even though local zoning or land use regulations might seem to preclude them. If you have clay soil (who doesn't in the NE) you don't need a plastic liner.>>
Yep. I supervised the construction of a farm pond on a neighboring property many years ago but that was then. The town's zoning has since changed so that, even though there's no village in our township, my property is now in an area designated the "town center" and is zoned strictly residential. That has it's good and bad points, none of which are pertinent to this discussion but it does mean that I'd probably have to go before the ZBA board to get a pond approved. As there are two homes in close proximity to that part of my property, the desires/concerns of those homeowners might trump mine.
I have often considered the idea and think it's a good one.
After the obvious question of load bearing, I think cross buttresses of CMU laid sideways will prevent wall collapse in empty times.
Something not so obvious is keeping car contaminants out. There are several makers of membranes that can be used as lids, but all would require a layer of concrete topping. Might only have to be a couple of inches thick. You would need a curb around the access port.
The inner walls can be waterproofed with Xypex, a cementious product.
A 20' x 24' cistern would hold about 3800 gals for each foot of depth.
SamT
Anyone who doesn't take truth seriously in small matters cannot be trusted in large ones either. [Einstein] Tks, BossHogg.
Sam,
Thanks for getting back to the question. You make the one point which has always drawn me back to this idea. The capacity of such a cistern, even at only four feet deep, is more in keeping with the amounts which my lawns and gardens could require during a long drought.
Ever since working on the construction of two federally funded sewage treatment plants, I've known that this idea was feasible. We built concrete forms for large free standing tanks, 16' high. The walls were 8" thick with a serious amount of rebar tied in the middle. It seems to me that a tank of half that height could be built with a lot less rebar, more like what would normally be required for a foundation. I've also had in mind to add a center dividing wall, both for support and to have the option of separating the water collected off the roof from what might come off the driveway.
I don't know if you are familiar with Harrowsmith Magazine. It was a back-to-the- lander type publication, and I remember it ran several articles on basement cisterns that were used for drinking water. Not sure if they have an archive online.
Several years ago, I poured a 20' x 20' x 8' high concrete cistern that stood above ground. Recently I was driving by and some clown had used it as the foundation for an addition to the house. Seems fine.
I just bought two 2,500 US gallon plastic potable tanks. Here they run about a dollar (Canadian) per gallon. That buys quite a bit of concrete and steel.
<<Several years ago, I poured a 20' x 20' x 8' high concrete cistern that stood above ground. Recently I was driving by and some clown had used it as the foundation for an addition to the house. Seems fine.>>
Do you remember any of the specs? Or do you know where they can be found?
I see that you live on Vancouver Island. I've had the pleasure of exploring a bit of your country, beginning with a day ferry trip down the coast from Prince Rupert to Port Hardy, then a few days driving around, visiting with some wonderful BC folks in various places, both coasts and some smaller islands. I sure could get used to living the BC life, no question.
It had 8" walls with a 6" slab covering it. There was also a centre wall, so the slab only spanned 10'. I recall the engineer had steel both ways at about 16" in the walls and 12" in the slab. We did not line it, I painted on zypex and it held water fine.
When we were stripping the forms, a large piece of concrete fell off a whaler onto my head. My buddy, who couldn't see me, asked if I was alright. He says I replied "No, I'm knocked out". I don't remember. That night the homeowner called me and asked if we had slaughtered a deer by his backdoor there was so much blood.
Glad you liked B.C. For me, New England in the Fall beats any scenery out here hands down.
Yes, fall colors in NE are like nowhere else on the planet. Even in Europe they don't see anything like it, just some vague yellows. Nonetheless, Vancouver Island has many unique charms, most of which are not limited to one season.
Hope your attached garage foundation is located where a tank failure would not put water into lower level of home!
On 10 Acre lot with mostly trees, not lawn, I will be putting a 5000g tank under roof in a detached shop building. Plastic tank, 8-10'dia and set on compacted fill, not conc. floor or foundation. We will be using it for potable water supply so collect from roof only. Large dia line from gutter to tank. Then pump thru treatment & filters to adjacent 200gal conventional pressure tank.
5000gal more or less 20 ton in a flat bottom tank is not a problem to support if not involved with floor or foundation concreate. Look at small contact points where truck tires are on the ground.
Okay I'm going to just come out and say it. Why in the world do you need so much lawn? Don't you live in a Desert area? Why import a lifestyle from places where it rains in the summer to an area that has very little water? Ever fly into the Las Vegas airport? It is high desert and you can see all these green lawns spreading out with the suburban sprawl. It just doesn't make any sense. They are sucking all that water up for green lawns in the desert.
Daniel Neuman
Restoring our second Victorian home this time in Alamdea CA. Check out the blog http://www.chezneumansky.blogspot.com/
Oakland CA
Crazy Homeowner-Victorian Restorer
Don't you live in a Desert area? Why import a lifestyle from places where it rains in the summer to an area that has very little water?
He's in New York, so he gets plenty of rain. He's using rain water to irrigate, so he isn't doing anything but collecting runoff and spreading it around. If anything, he's helping replenish the ground water by storing it and spreading it gradually. Now, why he wants to spend the money and time and trouble to keep his grass green is another question, but I don't think he deserves criticism on the environmental front, at least as to water usage.
wait I thought this was somewhere in Arizona we were talking about...new york....huh well then my original critisism doesn't really apply...
Daniel Neuman
Restoring our second Victorian home this time in Alamdea CA. Check out the blog http://www.chezneumansky.blogspot.com/
Oakland CA
Crazy Homeowner-Victorian Restorer
<<Okay I'm going to just come out and say it. Why in the world do you need so much lawn? >>
I probably won't have that much lawn but I'd like to have that option and some others that require plenty of water.
Maybe I'll put in a putting green or a lawn tennis court. Putting green is on the boards. They need water, every night.
I'd also like to keep the native stuff thriving all summer and fall too. There are about one hundred species of wild flowers in the area. Keeping them blooming in profusion could require water.
Another possibility is a swimming pool. I spent several summers installing them so it's a skill that I'd like to put to use for my own pleasure now. The evaporation from a pool can run into the hundreds of gallons per day.
I'd like to work a small waterfall into my landscape too. I've built a few concrete fish pounds with waterfalls. They're easy to put in and they add a lot to an informal garden, particularly when the property slopes like ours does. So that's another place where water evaporates.
A big vegetable garden is a strong probability. We've got an acre or more of rich soil. We could get serious about growing our own organic food. The way stem cell research is going, we may all end up living an extra fifty-sixty years. That means that world populations will rise. And the way oil prices are going, and climate changes are going we might need to feed ourselves or pay dearly for our food. I want to be self sufficient in my retirement and enjoy living as long as God and medical science allow me to live.
I believe that when a large property is involved, putting a four to eight foot deep cistern under a two car garage, as an extension of the foundation, is a good investment. Just like it makes sense to face the garage south and build a 12/12 roof on it. It may take another ten years but the day will arrive when photovoltaic panels become more efficient and economical, worth the investment.
Don't forget the outdoor rain water solar heated shower. It's great.