Perched Aquifer Property Damage

Hi all, need some advice.  I heard that some folks living in my metroplex had their homes built on what ended up being a perched aquifer (going with the terminology from the experts quoted in the article).  Lots of finger-pointing*, but long story short, folks are getting foundation damage and sump pumps aren't quite cutting it.  For context, these are slab-on-grade, and we're dealing with clay and limestone (this is central Texas).

I emailed the city employee who's heading up the work an idea to use eucalypts to suck out the water (like the swamps around Rome in the '30s).  Her answer was along the lines of "that's interesting, here's a citizen committee you can join".  I'm thinking of attending to help however I can from a permie perspective, but would like to have more than one real idea to share.

So yeah, anyone got ideas?  Earthworks may or may not be an option (these are tight-packed houses with only 5 feet of offset from plot boundaries...not much space).  Here are the ideas the committee has been looking at so far:
1. Do nothing.
2. Route sump pump discharge directly into storm sewer.
3. Pursue installation of City-owned dewatering infrastructure.
4. Provide guidance to homeowners on sump pump improvement.

I'm no expert, but all those sound pretty bandaid-ish to me and I really think we can do better.  Ideas very welcome.  Many thanks!

[EDIT] - Here's a link to the study done on it:  https://www.ci.buda.tx.us/DocumentCenter/View/9459/Buda-WH-Seepage-Findings?bidId=

* Builder says their soil tests before building all checked out.  Homeowner's don't think that's good enough, and there's a legitimate worry that property value essentially drops to zero with this problem.  Foundation warranties expired years ago, and there's already been a lot of foundation repair (which still didn't fix the problem) from the builder throughout the neighborhood.  City has been experiencing some road damage due to this as well.

What if you put in a well and used that water for gardening, washing the car, and the siding etc. You could perhaps put the well in a corner so that 4 neighbors could plug into the well and pay for pumping their water. It wouldn't have to be deep which would make the cost of the well much less. This would cut your water and sewer bills.

When I think of how much water my Christmas tree uses your tree idea sounds good. Seems as though your tree needs a tap root, which means a tree grown from seed. Peaches are said to grow edible fruit from seed. Or perhaps citrus. You can grow an apple seed and then graft a tasty apple scion to it. Something appropriate for your USDA. Fameuse apples grow apples from seed which are similar to the apple you ate and saved the seeds from. but that apple doesn't sound like it would match up with an area where eucalyptus would grow.

Once you have a well you can have the county test the water. Here they only test for bacteria for free. It's possible that the water table is potable especially if you go deep enough. Might be worth finding someone who has a well and has tested it to find out how deep they are. But then if your water source comes from a municipal well you may already be sucking water out of that aquifer.

Hey neighbor,

I read a local news story about the perched aquifer issue a couple of weeks ago. Thanks for the link to the study. I think for the near term John's multiple shallow well pumps sounds like the best option but I think for the longer term I like the idea of planting water loving trees. There's that water detention area right there that would be a great spot for a stand of cypress.

Oh, Groan.

I imagine these buildings never had proper footings did they?

All buildings, no matter how solid the ground may appear, need a proper foundation with a proper footing poured, but it looks like that information is too little too late.

If it were my house I would go with one (or both) of two options.

Option #1.  A real set of outdoor sump pumps should be able to take care of the problem.  It involves digging one or more deep (10’+) hole in the ground complete with concrete lining and a gravel base to allow water to percolate in.  Once pumped, the water will need to go somewhere so that means above ground grading or plumbing into existing storm sewers (not my favorite option).  I don’t really like this option because it requires power, won’t work during a blackout, requires maintenance in a deep hole (I have done it!) and generally has numerous points of failure.

Option #2 is far simpler but won’t work on every parcel of land.  Simply grade the land to drain the water away from the building.  It takes some upfront work, but is totally passive and works extremely well during a heavy rain.  When looking for a place to build our house we deliberately chose a place with a good gradient to drain water away passively.  The footings to our foundation actually have a piping system built in (called form-drain) that drains every drop of water that reaches the foundation.  We have an almost dusty dry basement in a humid climate.  Water is not a concern.  But obviously this works where the land works.

I wish I had a cheap and easy alternative but I don’t and my experience is that water problems are rarely cheap or easy.

Best of luck,

Eric

I don't have time to read the whole article right now, but this statement is really important and has been an issue in communities on the Island I live on:

Shallow groundwater in a perched aquifer can cause expansive clays underneath slab foundations to shrink and swell, leading to the shifting of those slab foundations.

In simple-speak, to save those foundations, you *have* to get the water levels low enough that the clay underneath the slab doesn't change its state. One thing the homes on the Island were told to do was Xeriscape - water-free landscaping with rocks and extremely drought tolerant plants - as a pre-requirement for gov't funding to help repair the foundations.
What I haven't gotten to is how the water in the "perched aquifer" is connected to ore interacting with the rest of the local aquifer system - does the article go into this? I always worry that solving one problem might create a much bigger problem downstream if the solution doesn't preserve overall water supply. Testing that water for potability seems crucial. If it's near potable, using it for showers/toilet flushing for the region would require a lot of plumbing work!

Hi all, thanks for the feedback (and hi, Aaron, good to see other permies nearby).  I haven't read through the whole report, but from what I can tell there's the Edwards Aquifer down deep.  Above that is limestone, and then nearer the surface (< 10' from the surface) there's a sandwich where the "bread" is relatively impermeable clay and the filling is sand, gravel, cracked limestone, etc (stuff water flows through).  And it's that middle layer that's forming this near-surface aquifer and causing all the trouble.  As to the construction of the foundations, I can't really speak to that.  If I had to guess, it's a slab poured with a grid-like shape underneath and a bunch of pipes running through it.

Speaking of unintended effects, elsewhere in the report it was mentioned that the overall grading of the land changed since before construction, and that seems to have shifted the underground water flow.

I had a similar idea about that water retention area: prime real estate for some water loving trees.  It looks like there are more of those areas throughout the neighborhood as well, as well as nearby parks (uphill, even).

The idea of one or more shared wells is a good one.  It sounds like a larger set of pumps that flush the water into the normal stormwater runoff system is what the city was already leaning towards, so it'd be nice if the water could be put to better uses.  Surface uses might be okay, not sure if it would just feed back into the problematic system underground.

As mentioned, power outages can be problematic so ideally something passive would be best.  That said, the only time I can recall this part of Texas having significant power outages was last year's "snowpocalypse" (I prefer to call it the Midwinter Jicker).

folks are getting foundation damage and sump pumps aren't quite cutting it.  For context, these are slab-on-grade, and we're dealing with clay and limestone

Brian, I understand your concern.

Are you having issues or have heard of the issues and want to help?

I emailed the city employee who's heading up the work an idea to use eucalypts to suck out the water (like the swamps around Rome in the '30s).  Her answer was along the lines of "that's interesting, here's a citizen committee you can join".  I'm thinking of attending to help however I can from a permie perspective, but would like to have more than one real idea to share.

I feel it would be good to join this Citizen Committee so that you can learn more.

I don't know about using "eucalypts to suck out the water" as I don't know what this is.

I am on the Edwards Plateau, one plant that I have always hear that a person does not want because it sucks up the water is Salt Cedar.  This is not the Junipers that ranches also say they don't want because of that same reason.

I do not see this as the City's problem.  The homeowners need to be getting together to take action themselves that is why I asked if you are having issues.

Brian Guetzlaff wrote:

I had a similar idea about that water retention area: prime real estate for some water loving trees.  

Yes, planting trees from seed (for a good deep root) would definitely be a low tech way to solve the problem.

Have you considered starting a specific thread in the growies tree forum to get some ideas of a guild of trees and shrubs that might provide food for the community as well as other benefits? I've heard that pecans are an issue because they need a lot of water - same with almonds, although I don't know if they grow in your eco-system. Eucalyptus is actually considered invasive in many areas, but if firewood is considered useful, there might be a place for some of them - I don't know if anyone has tried a "coppice" system for Eucalyptus, but coppiced wood is not just for firewood - charcoal, garden stakes, fencing, and many more uses. Peaches and Kiwi vines also both like water.

So what I'm hinting at is to take a map of all the green space that is available or could be made available, and start designing a permaculture-based food forest with a lot of variety of plants that both bloom and produce fruit/nuts at different times of the year, and that will soak up that water. My idea is to plant the neighborhood and greenspaces in an inviting, people-friendly way that gets everyone on board. Brad Lancaster actually planted Mesquite, but it pumps water down into the soil in the wet season from my understanding. The question is, how deep do its roots grow - would that plant increase the problem, or coupled with plants that want water, would it be a valuable part of a integrated system?

Permaculture is know for saying, "the problem is the solution" - it's just figuring out a few options for getting there.

I am puzzled as to why a clay layer that far down, topped by gravel, sand, [okay the limestone could "help" transmit heaving pressures] are causing these problems. Are they uniform thru out the housing development? ie. are all house "foundations" being affected? Are all slab on grade or do some have perimeter footings independent of the slabs. My guess is that the live loads [eg. snow] are nonexistent in that climate.

Maybe screw piles could be of some help. Pretty much everywhere in the world has clay.

Anne Miller wrote:I do not see this as the City's problem.  

I see a potential for it being at least partially the city [State] to blame, or if there was at developer, as they/whoever ought to have done overall studies to ensure that the ground conditions were okay to meet seviceable conditions for foundations used in that area/city. If this is a very localized problem then someone other than the homeowners bear some responsibility.

Some information on the Edwards Aquifier may help people understand what is going on:



https://www.edwardsaquifer.net/intro.html

The Aquifer is divided into three main zones: the contributing zone, the recharge zone, and the artesian zone.  The contributing zone occurs on the Edwards Plateau, also called the Texas Hill Country.  It is about 5,400 square miles, and elevations range between 1,000 and 2,300 feet above sea level.  The rugged, rolling topography is covered with thick woodlands of oak and cedar.  Today, the Edwards Plateau bears little resemblance to the prairies the pioneers to the area saw, but it is home to several endangered species and is itself the subject of increasing environmental concerns.  The contributing zone is also called the drainage area or the catchment area.  Here the land surface "catches" water from rainfall that averages about 30" per year, and water runs off into streams or infiltrates into the water table aquifer of the plateau.  Runoff from the land surface and water table springs then both feed streams that flow over relatively impermeable limestones until they reach the recharge zone.

The recharge zone is a 1,250 square mile area where highly faulted and fractured Edwards limestones outcrop at the land surface, allowing large quantities of water to flow into the Aquifer.  For this reason, the Edwards is often called a fault-zone aquifer (see section on Faults & Caves for fault map and photos).  About 75-80% of recharge occurs when streams and rivers cross the permeable formation and go underground.  This is called allogenic recharge. Most of the remaining percentage of recharge occurs when precipitation falls directly on the outcrop. This is called autogenic recharge.  A surface water reservoir built partly on the recharge zone,

Here are some of the problems from the past:







I am sorry this is happening to these homeowners.

Terry Byrne wrote:

Anne Miller wrote:I do not see this as the City's problem.  

I see a potential for it being at least partially the city [State] to blame, or if there was at developer, as they/whoever ought to have done overall studies to ensure that the ground conditions were okay to meet seviceable conditions for foundations used in that area/city. If this is a very localized problem then someone other than the homeowners bear some responsibility.

The tendency in so many things that might involve large amounts of money, is to start finger-pointing and playing the blame-game. In a perfect world, people would meet and come up with multiple creative solutions to solve the water problem - situations like this may take multiple approaches to get the over-all fix. Yes, eventually, people will have to negotiate who will pay for this in the short term or longer term, but the city would have access to levels of government who may have experts in hydrology whose job it is to know some of these options and the people who may be able to arrange either home-owner grants or low/no interest loans so that no one loses their house over a problem that should have been identified before houses were built.  I'm no expert, but it seems to me from all the reading I've done about permaculture that this problem can not only be fixed, but if it can be done with trees, it may be a pretty reasonable cost.

Well, Brian, It doesn't look like your city is very cooperative but there is an app for that. It is called Citizen engagement.
First, I had to look at what a 'perched'  aquifer might be because I had never heard that term. Looking at the pictures:
https://www.waterscience.co.za/dictionary/index.html?introduction_perched_auifers.htm
and at the study you linked, it looks like those properties are essentially above a basin of water which is very close to the surface, so that every time you get more rain, your feet get wet.
Something that is troublesome is that in 2002, there was no subdivision there. Did it *look* like low land even before the first construction began? Unless the *construction* itself is what brought headaches for the residents, I'd say the builders didn't do their required due diligence and now, they want to wash their hands of your problems. It looks to me like they did a 58 page study to tell you essentially nothing you didn't know before. I recognize the pattern of behavior from officials we have around here dealing with groundwater too. I'm a water officer for our local ground water that is getting manured plenty and getting legislators to move is like pulling teeth!!
I gleaned this from Springer link:
" Perched aquifers do not usually make large or reliable sources of water supply, and it sometimes happens that [b]the act of drilling or deepening a well in a perched aquifer penetrates the impermeable layer and allows perched water to drain through to the aquifer beneath. Common occurrences of perched aquifers" .[/b]
https://link.springer.com/referenceworkentry/10.1007/1-4020-4497-6_109#:~:text=Perched%20aquifers%20do%20not%20usually,through%20to%20the%20aquifer%20beneath.&text=Common%20occurrences%20of%20perched%20aquifers.
I'm giving you the link where that quotation came from but trying to open it, I could not get the whole article.
From the quotation above, it sounds like John might have the best solution: Pierce through to the groundwater and that might solve your problems. You might engage your neighbors to pitch in for a common goal of piercing through. I notice that the groundwater might be around 140 ft deep, so that is not something that 9 property owners could deal with.
Would the town be amenable to piercing through? [after all, you mention road damage, which also costs $$$, and there may have been negligence, so...?]
Here, in Wisconsin, we have folks that bought low laying property [it was cheaper, so trailer homes area and little taxpayer $$$ available for remediation] they threatened to sue the town and the town tried to fix it. We will see this spring if they did. I feel for those folks but in all fairness they bought the wrong properties, yet our town helped. Your town might be moved to do something too. Don't despair.
How do you get your drinking water? If it is town water, it is entirely possible that your town is pumping from it, in which case drilling through to groundwater might cause more problems than it solves.
Start making every town meeting and don't hesitate to make yourselves obnoxious [within reasonable limits, of course] until they come up with a better solution.
As far as planting vegetation that would 'sop up' the excess, I like basswood, and if it grows in zone 8 *and* you can plant it far enough from foundations, it might be the ticket [looking at how close the properties are, though, I wouldn't].
Another idea would be to request the town build a big public swimming pool where the neighborhood kids could go play. The pool should be built some distance and all the water for it pumped from the problem zone and the water from periodically emptying the pool could be run off farther away. Think of it not as a problem but an opportunity, I guess.
Good luck to you!

As for water loving tress I would consider Weeping Willows. They provide lots of shade and use lots of water.

Chris Tully wrote:As for water loving tress I would consider Weeping Willows. They provide lots of shade and use lots of water.

Looking at the scenery, this is a suburban area with lots of houses. It is true that weeping willows [all willows, really] grow fast and a mature tree weeping willow can drink 100 gallons of water *a day*, which might be really helpful, were it not for the ability of their roots to displace stuff we don't want displaced.
"Weeping willow tree roots are aggressive, invasive and shallow, and they can spread up to three times the length of the tree (from the trunk to the canopy). The roots often lie close to the soil surface, causing bumps in the lawn, which interferes with mowing. They can also lift cement patios".  https://sciencing.com/root-system-weeping-willow-6300180.html
The linden Tilia Americana that I mentioned in a previous post is less aggressive but it too does not have a deep taproot, so for the problem mentioned this may not work as the best solution either if the goal is to pierce through to the lower aquifer but I agree with you that something that would suck water aggressively might help.
"Basswood has large lateral root system and usually not a taproot. Seedlings do well in shade but development requires full to partial sunlight. Moist rich soils are best.".
https://www.friendsofthewildflowergarden.org/pages/plants/americanbasswood.html
The Tilias  may bring their own problems such as bees, which, [I'm a beekeeper] would not be a big problem since they would land on the flowers, but still, if a person is allergic, that requires consideration.
For a band aid solution, I was wondering about water loving trees and shrubs. This is what I found, for trees:
"Some of the best trees to plant in an area with a lot of water are willows, coast redwood, California sycamore and Eastern red cedar". For bushes:
"Try blue elderberry, Pacific wax myrtle, Western false indigo, desert willow, highland blueberry or Western dogwood shrubs in areas with lots of water. They'll flourish, instead of dying, because they are able to continue getting nutrients from very wet soil." https://homeguides.sfgate.com/waterloving-trees-shrubs-25213.html
If a person doesn't care about having a large lawn, perhaps planting tightly a lot of bushes that like wet areas would work better than one or 2 trees which might take a long time to reach the mature size at which they suck the most water. In the list of shrubs above, realize that highland blueberries require a very acid soil, so do a soil test before planting.
It might help to ask the town to provide these since the problem seems due [IMHO] to negligence by the developers/ the town that gave the building permit?
Why did they give the green light on construction as the site seems to have been unsuitable for such a large development?

Cecile said, "negligence by the developers/ the town that gave the building permit?
Why did they give the green light on construction as the site seems to have been unsuitable for such a large development?

What people do not understand is that the whole Hill Country part of Texas has these problems.  It is a large amount of land with a very large population.

I live there on top of a mountain.  Who knows what is under my house?  

Cities were once small then as the city's populations grew larger there had to be land for these people to live on.  Then these cities grew even larger and some of the least likely lands became developments, etc.

Whispering Hollow Subdivision, Buda, Tx
https://www.ci.buda.tx.us/DocumentCenter/View/9459/Buda-WH-Seepage-Findings

I had time this morning to read the finding of AquaStrategies which is a Water Planning, Science & Engineering Company.

The City of Buda, Tx hired them. If anyone is interested in the findings:

On p.42 is the recommendation. 3.  Conclusions.

p 51 3.2.1.3 Option 3 talks about the installation of city-owned dewatering infrastructure.

p55  3.2.1.4 Option 4  Provide guidance to homeowners on sump pump improvements

News articles:

https://haysfreepress.com/2022/01/17/dewatering-solutions-discussed-for-buda-subdivision/

https://www.kxan.com/investigations/somebody-messed-up-water-flowing-under-buda-homes-for-11-years/

I feel it is best not to place blame on people.

Brian wants to talk about plants that use a lot of water.

Let's talk about plants.

I had not realized that weeping willows have such a shallow and wide root system. With the comments about needing a tap root, consider the long leaf pine. It starts life as not much more than a tall sprig of grass. It spend the first ten years putting down a a tap root at a rate of about 1 ft per year. Then in the 11th year it starts to look like a tree!

Great ideas!  To answer a few questions I saw posed:

I live nearby, but am not in one of the affected homes, so this is more of a "want to help" situation.  That said, it wouldn't surprise me if this was happening more broadly as well (I live nearby, so this isn't purely selfless, I must admit).

All the houses in the neighborhood are slab-on-grade.

Snow is relatively rare around here.

Buda gets its water from several places.  Much is pumped from the ground, some is piped in from elsewhere.  Groundwater pollution is a consideration.

Salt cedar is interesting, I'll need to look into it.  As I read through these responses it got me thinking more about the kinds of root structures that would be helpful here.  It seems likely that plants that have the shallow aggressive roots can get very thirsty, but may be drinking from the wrong water source in this case (too near the surface).  Thirsty taprooty trees might be more fitting here.

Hadn't considered the Growies forum, but that's an excellent idea and I'll put something over there as well.

Going for a full-on food forest would be fantastic!  Since the most likely mass-planting areas are the drainage/retention areas, though (and city-owned), not sure I could swing that.  Maybe get it planted to some initial trees, and other useful goodies just, you know, happen to appear over time.  I imagine lots of folks go on walks around there.  ;)

In terms of who is to blame and who should pay, at this point I think it's too far past (over a decade) to establish blame, and frankly it doesn't really matter much.  The people will pay, either directly or through taxes (or reduction in property value).  My hope here is that whatever solution we come up with is long lasting (dare I say, PERMA-nent?) and cheap, hence my focus on well-chosen plants.

The suggestion to pump from this problematic layer into something usable like a public pool is definitely intriguing.  Looking at the maps, the only area downhill is drainage into Garlic Creek.  Nearby there does seem to be a new housing development going in (east of Whispering Hollow).  Not sure if a pool of any sort is planned there, but that's certainly something to consider.

Weeping willows might work.  Shrubs are definitely fair game as well!  I wish we could grow blueberries and other acid-loving plants here, but it's tricky (limestone = fairly alkaline soil... 8.5 in my yard last time I tested, it ain't pretty).  But still, I think there are likely lots of good options that would be able to handle alkaline clay soil.

Thanks for the ideas everyone!  Please keep them coming. :)

[EDIT] - Growies thread here:  https://permies.com/t/176819/THIRSTY-tappy-plants-alkaline-clay

With a soil Ph at 8.5, you can put a cross on blueberries. They would do well in a damp area, but unless you can go down to 4.5 to 5 with amendments, it is not likely to work. I have a Ph of 6.5 and they need to get yearly amendments or I don't get blueberries.[ plus it is sandy here!
Packing in water loving plants may indeed be the best option.