Need some DEEP French Drains, how can I do this or hire someone?

[mancho]

Thank you for the insights!

I am not aware of geotechnical engineering forums on the web, I will dig for those.

The problem with our property, much like the neighbors, is that we have some strange water sources, and the "clay" expands significantly.

Its not that our house is "sinking" as much as it's being heaved up into the air.

I will post the engineers report from 2005 (we bought the house knowing this info):
http://www.picklebush.com/05-187_Armstrong_Diagrams.pdf

I have another engineers report from 2009 that I will find...

What you see is the engineer recommending putting piers under 3/4 of the house to match the side that is HIGHER. The low side is because of all the heaving on the LEFT side in the diagram (the E> marks).

Thoughts? I like the pavement idea for run off, but I'm still thinking "extreme french draining" next to the foundation is the long term route.

 

[inveresk]

Thanks for fleshing out the picture. As well as drawings, did you get a purpose statement from your engineer advising what the nature of the problem was in layman's terms and what he was trying to achieve? That might explain everything and give you confidence in his solution. I'd also ask him for a method statement for how he would foresee the works being undertaken. That type of document is very helpful to a contractor.

Here is what I understand the nature of the problem is. As you say, clay expands and contracts as it gets wet and you've suffered substantial heave due to surface water run off from a neighbouring property and you have to do two things - solve the problem of heave and also level the house. If the piling is not to level the house, perhaps the piles are needed because once you install the french drain, the clay under the house will dry out and shrink and so the piles will stop the low side from subsiding? If the high side has no piles, is he hoping the house will level out and that if he lets the high side settle but not the low side, the house will reach an even keel? What does your engineer say he is trying to achieve? A purpose statement from him would remove any guesswork.

I'd still consider a drain on your uphill boundary to get rid of the surface water coming from uphill. This will reduce the amount of water getting to your foundations but also make your yard drier and so more usable.

I sit roughly in the middle of eleven gently sloping acres of heavy clay. The uphill boundary is about 500 feet away and once the ground gets waterlogged, the run off is severe. I've cut two swales between my house and my uphill boundary, both pretty shallow. One is about 80 feet from the house, the other on the other side of our riding ring about 300 feet away. All we have around the house is the normal circuit drain. Even during our wet season our yard remains good and firm.

A surface drain or swale on your boundary will be much cheaper and easier to do than a french drain around the house. As I understand it, it should also get rid of the water source which is the cause of much of your problem although, of course, it will do nothing to help level the house.

Has it been explained to you that to undertake the piling you're going to have to raise the house? How else do you get the piles under the foundations and those within the body of the house? Also using steel piling has it's risks and needs very competent operatives. This article explains. Steel Piling Method of Foundation Repair

You're in for an expensive and disruptive solution. Make sure you fully understand what is happening and why. It's not rocket science and your engineer should be able to describe the problem and the design solution so you understand it and have confidence in him. If he can't, get a second opinion.

Here is a link to a foundation repair forum. I'd make a posting and ask for advice. I woudn't mention you have an engineer, just tell them the nature of your problem - all of it - and ask what they would recommend. Do give them the whole picture.

Foundation Repair - NAWSRC Public Help Forum

 

[CurlyDave]

If you are not planning on leaving the house any time soon, you have time to try a much less expensive approach in stages.

1. Is the heaving any worse than in 2005? You have the engineer's plot and can check current elevations with a water level. Cost is a few hours and maybe $25.

If it isn't getting worse, or not much worse, I would try a swale to direct run off around the house. This can be inexpensive, and you can re-check interior elevations in a year or so to see if it did any good.

In my neck of the woods, a 9' deep french drain would be called a "curtain drain" and it may turn out that you don't need on that deep.

I would try a 3' one, hand dug close to the house. I know how cheap you can get unskilled labor in Texas, and this is probably in the $1000-1500 range. Again, let the result of this stabilize for a year and recheck interior elevations.

For a 9' trench you will need an excavator or a backhoe. It is extremely dangerous to enter a trench more than 3 to 4' without proper shoring. I would not ever ask someone to dig a trench that deep by hand.

 

[inveresk]

If you are not planning on leaving the house any time soon, you have time to try a much less expensive approach in stages.

1. Is the heaving any worse than in 2005? You have the engineer's plot and can check current elevations with a water level. Cost is a few hours and maybe $25.

If it isn't getting worse, or not much worse, I would try a swale to direct run off around the house. This can be inexpensive, and you can re-check interior elevations in a year or so to see if it did any good.

In my neck of the woods, a 9' deep french drain would be called a "curtain drain" and it may turn out that you don't need on that deep.

I would try a 3' one, hand dug close to the house. I know how cheap you can get unskilled labor in Texas, and this is probably in the $1000-1500 range. Again, let the result of this stabilize for a year and recheck interior elevations.

For a 9' trench you will need an excavator or a backhoe. It is extremely dangerous to enter a trench more than 3 to 4' without proper shoring. I would not ever ask someone to dig a trench that deep by hand.

Good advice.

 

[Joe H]

You mentioned a HOA so I assume you're in a built up area. Where is this proposed drainage to go? Onto a neighbor's property? Street? Storm drain?
Seems like diverting the water before it gets to your house would be the easiest, and making sure you have a good raingutter system that also flows the runoff far enough down hill.
A 9' deep trench the width of even a narrow bucket is one **** of a lot of dirt, better put an ad on craigslist right now for free dirt.
Good luck, I hope the purchase price reflected the needed repairs. Joe H

 

[mancho]

You mentioned a HOA so I assume you're in a built up area. Where is this proposed drainage to go? Onto a neighbor's property? Street? Storm drain?
Seems like diverting the water before it gets to your house would be the easiest, and making sure you have a good raingutter system that also flows the runoff far enough down hill.
A 9' deep trench the width of even a narrow bucket is one **** of a lot of dirt, better put an ad on craigslist right now for free dirt.
Good luck, I hope the purchase price reflected the needed repairs. Joe H

Thank you for all of the insight and expertise. I will review the links that have been submitted.

I have posted the last engineers report here, from 2008, and you'll see while he does NOT recommend piers, yes watering, and the last sheet explains why, he says nothing about french draining:

http://www.picklebush.com/Pranther_Engineering.pdf

To answer some of the great questions in this thread:

If the piling is not to level the house, perhaps the piles are needed because once you install the french drain, the clay under the house will dry out and shrink and so the piles will stop the low side from subsiding?

>>The thought is from the engineers in the area, is the concern if the water/expansive clay is removed, that the house will level back down to something, maybe not perfect, much more closer to a level original build.

If the high side has no piles, is he hoping the house will level out and that if he lets the high side settle but not the low side, the house will reach an even keel? What does your engineer say he is trying to achieve?

Yes, even keel and then consider piles if needed. What they want to achieve is obviously the heaving causing the house to be out of level... I guess I'm not really understanding the question, sorry.

>> A purpose statement from him would remove any guesswork. The second engineer report attached in this post has a purpose... I think?

I'd still consider a drain on your uphill boundary to get rid of the surface water coming from uphill. This will reduce the amount of water getting to your foundations but also make your yard drier and so more usable.

>> I totally agree, but oddly, if surface water typically travels in the top 24 inches of ground, then why is the neighbor going 9feet to prevent any surface water. The neighbor is to MY NORTH, where the maximum swelling is.


A surface drain or swale on your boundary will be much cheaper and easier to do than a french drain around the house. As I understand it, it should also get rid of the water source which is the cause of much of your problem although, of course, it will do nothing to help level the house.

>> Maybe, the water source, while not really known exactly, is to the "EAST, SOUTH EAST, the high point of the hill... but my house isn't suffering on on the South East/South side... that side is actually low!

Has it been explained to you that to undertake the piling you're going to have to raise the house?

>> Yes. We have bids from 15K to 50K to raise the house. Interior damage is not in those estimates (pipes, sheet rock, windows, etc)

How else do you get the piles under the foundations and those within the body of the house?

>> They drill a man size hole through the foundation and f'up the floors.... not something we really want to do.

1. Is the heaving any worse than in 2005?

>> Looking at the 2008 report, I would suspect yes. Our cracks on that side of the house continue to expand and we're seeing new movement/damage in other areas.

I hope the 2nd engineer report gives some good information. I would of hired the original firm, but they never returned my phone calls. Both of the reports cost around $400.

I think my next steps:

1. Get french drain quotes for a "Horse Shoe" shallow (3 to 4 feet max) around the pool backside (see image) . This is the PURPLE.

2. Consider a "curtain drain" next to the foundation but only 5 feet deep? This is an uneducated guess.

Notes: When the neighbor to the NORTH put in a sump pump on the alley back side of the house (east), it didn't do any good, because the water flow is from the EAST/SOUTHEAST. However, the south side of MY house has no movement UP, only down.

The ORANGE 1 foot deep french drain between our properties has little to NO effect on stopping water to the neighbors house.

I frequently still have a puddle of water sitting between our houses, so I am not sure it is really doing anything, might be clogged.

THE LIGHT GREEN is my house PROPERTY LINE and the circular area over the house is the area that is HEAVING EXTREMELY.

I think with the image I presented, the 2 engineering documents, and some good insight from you folks, I can at least start phase 1, and that would be the horse shoe drain, approximately 4 feet deep. It might not get the HEAVING to stop on the NORTH side of the house, but it should cut down on the amount of water getting to the house.

Thoughts?

 

[mancho]

You mentioned a HOA so I assume you're in a built up area. Where is this proposed drainage to go? Onto a neighbor's property? Street? Storm drain?
Seems like diverting the water before it gets to your house would be the easiest, and making sure you have a good raingutter system that also flows the runoff far enough down hill.
A 9' deep trench the width of even a narrow bucket is one **** of a lot of dirt, better put an ad on craigslist right now for free dirt.
Good luck, I hope the purchase price reflected the needed repairs. Joe H

Sorry, forgot to answer this directly, yes, the water goes down to a drain runoff system near a golf course.

Diverting the water is good idea, but how deep is the real question.... more than 24 inches, but not sure a 10 foot deep french drain will solve all problems. This is a strange one.

 

[inveresk]

Seems to be a regional problem and your engineer seems to be on top of it. I wonder why the 9' deep french drains were not installed at construction. So much easier at that time. How long ago did your neighbour install the 9' french drain, and did it work?

That maximum heave is occurring on the lee side of the slope is odd and I'd suggest that be investigated. It could be due to something simple like rainwater or circuit drains being blocked or broken. Might be worth having a cctv survey to determine condition of drains on that side of the house, including the french drain between you and your neighbour.

 

[mancho]

The 9 foot drains are being installed by the neighbor now. So we won't know for some time if they worked... but sure has to be better than the sump pump on the back of the property.

I do not know what you mean cctv survey... a camera? There isn't any network drains. but interesting note, the "top of the hill" behind me has a massive water main that had sever issues 3 years ago and they dug up the entire street. However, that didn't stop the flow of water from that source, or somewhere near it.

Perhaps the "top fill" was over an old creek bed or something... this area was created by a developer that had no prior experience with this type of neighborhood... so there is many foundation problems in this area. Some of these hills are not natural, they are man made with some crappy clay.

Hopefully I answered your questions and NO, the engineers just come out, take measurements and give me a guessitmate that they are willing to sign. I need a hydrologist engineer I am told.

 

[inveresk]

Yes, I mean a video survey of your surface water drains.

Observing the operation during your neighbour's french drain install will give you some idea as to how it might be undertaken. Although if you have to raise your house it should be much easier and cheaper to do at that time. The services, for example, will have already been disconnected. At least get some feedback on your neighbour's operation and it's success before you sign up for major works.

Were it me, the french drain and piling would be the methods of last resort. There's a lot meantime you can investigate that might possibly help resolve the problem.

Not an easy diagnosis to make nor course of treatment to decide on. Good luck with the investigation and cure. Keep us posted, (with photographs wherever possible).