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Discussion Starter · #1 ·
Hi everyone,
I have a rental house which has issues with water sitting against the exterior wall (slab foundation) after a heavy rain. In once case where 4 inches of rain came down in a few hours, a minor amount of water came in the house. Of course, i am looking to remedy the situation. The house is on a flat lot and it is likely not possible to "daylight" the french drain. I would like to design a french drain/drywell and sump pump system with enough capacity to handle a 15 minute downpour with the power out before the pump comes on to dispose of the water in the dry well. I have 2 ideas detailed below, i hope it makes sense.

idea 1: Install a 1foot wide x 1 deep "french Drain" along the perimeter of the house, this section would not have dirt or grass but would remain gravel around the house for allow for quick drainage. This perimeter drain would be connected to a large "linear" dry well that runs the length of the yard in the middle of the yard (basically a 2 foot wide by 3 foot deep by 50+ feet long trench filled with gravel. At the end of the trench would be the sump basin with a 2" trash pump (high capacity). the drywell would be covered with topsoil and grass

idea 2: similar to idea 1, but rather than have a separate french drain and dry well, the idea would be to have one very large french drain along the perimeter. (imagine a a triangular ditch which starts at 6-9" deep along the foundation and gets deeper to 2-3 feet deep the further away from the house (6 feet or so). Similarly this would run the entire perimeter of rear sides of the house and end in a sump basin. teh outer 3-4 feet would be covered with top soil and sod leaving the bare gravel against the house to aide in fast drainage.

I have posted a photo, if it worked!

 

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Regrade the land so water flows away from the house.

If desired you could have a drywell somewhere away from the house where the water runs and you have a sump pump in case it overflows.
 

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Discussion Starter · #3 ·
Regrade the land so water flows away from the house.

If desired you could have a drywell somewhere away from the house where the water runs and you have a sump pump in case it overflows.
I should have clarified that with either of the plans i mentioned some degree of regrading would take place. I would like to avoid having a large swale right in the middle of the yard where folks will be using the yard. Plan 2 does change the effective grade right around the house, Gravel fills it somewhat level but the ground udnerneath has a quite substantial grade away from the foundation. The other issue is regrading the entire yard would also require resodding the entire yard. While an effective solution is required, this is a rental house so "good enough" is also an acceptable solution.
 

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Discussion Starter · #5 ·
The height of the outside grade does look rather high. How much higher or lower that outside grade is the top of the slab ?
It's pretty dang close to even. I'll do what I can to shave it down lower, but the layout of the property and surrounding properties will make significant regrading difficult. The intent of both of my solutions is to reduce the effective grade well below slab level. It is certainly a complex problem to resolve

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Have you done a perk test to see of the ground can absorb the water?

Downspouts are a problem if you do this plan add a second solid pipe for the downspouts.
 

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Discussion Starter · #7 ·
Have you done a perk test to see of the ground can absorb the water?

Downspouts are a problem if you do this plan add a second solid pipe for the downspouts.
No perc test, but it is Oklahoma clay- I dont expect much absorption which is the reason for the pump. The dry well is really just a large reservoir to collect a downpour in the event of a power outage where the pump will obviously not be working. The idea is power comes back on and the pump empties the dry well

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No perc test, but it is Oklahoma clay- I dont expect much absorption which is the reason for the pump. The dry well is really just a large reservoir to collect a downpour in the event of a power outage where the pump will obviously not be working. The idea is power comes back on and the pump empties the dry well

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but where will you be pumping too.
 

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The other issue is regrading the entire yard would also require resodding the entire yard. While an effective solution is required, this is a rental house so "good enough" is also an acceptable solution.
Although you might only see water in high rainfall events, my concern would be that in moderate rainfall events, the sill plate and joists could be getting wet and rotting away.
 

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Discussion Starter · #11 ·
Although you might only see water in high rainfall events, my concern would be that in moderate rainfall events, the sill plate and joists could be getting wet and rotting away.
Certainly a possibility on the sill plate, I would expect either of my solutions with some mild grading as possible may alleviate this. Home is a slab, no joists to worry about. I really wish I could just regrade away from house, problem is there is no significantly lower grade nearby to direct water to.

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Discussion Starter · #12 ·
I should add that I did have a pro out to take a look. He was going to do some grading where possible and then utilize a pump and french drain. His quote was over $10,000. Unfortunately not an option with this property

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It just amazes me nothing seems to be learned from history and houses are still being built on the flat or even in a hole with a basement. I suppose the reasoning is less expensive and simpler but has a builder ever seen rain like the record in Holt MO?

I've personally seen it rain 3" in 12 minutes. 12" of rain on a 2,000 sq.ft. house is nearly 15, 000 gallons and 3" of rain is about 3,700 gallons. Although swales aren't desired, that's the only thing that will come close to handling heavy rains and be nearly maintenance free.
 

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If I am reading it right, your solutions are just long linear gravel pits with no pipe taking the water at the house away. Don't forget those "linear pits" will be collecting the surrounding water too, which might saturate before water at the house even makes its way there. You want to transport the water away as quick as possible, not have it sitting like in a leach field.

No location, but if you have freezing, none of this works.

Rent a bobcat, regrade the entirety lower and sloped back to a small detention area that will percolate into the ditch.
 

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I should add that I did have a pro out to take a look. He was going to do some grading where possible and then utilize a pump and french drain. His quote was over $10,000. Unfortunately not an option with this property

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Alex, love the house! Wish I could have that kind of brick out here in the Land of Shaky Ground. Alas, after a quake, it would become one of those funeral stone piles.

I'm going to make a slightly desperate out of the box suggestion:

That looks like a new tract, where the clay was compacted for construction. We had a lot of developments like that out here, with similar issues. One dude came in after he ended up with about 5 inches of water in his living room, because it drained the wrong way, and there was no good place to run the water.

So, out of desperation, knowing the top soil was compacted, he, me and a sturdy helper dug deep through the hard stuff on top and hit a softer more permeable layer below. That provided a place for the water to run through, and he was able to avoid further trouble after that.

It was not easy. It was masochism. It would have made a great punishment for someone you really hated. We dug about eight feet. I was 25 then; after, I felt more like 125. Maybe 126.

One reason we decided to do that horrible digging was I ran across a map of by US Geological survey at the library that showed soil types; it turned out that his soil had been graded over another type of dirt. So it was worth a shot.

So, maybe get someone with an auger out to your place to bore down a few yards and see what's there? Or check a USGC map for where you are? Or, just get or force some people to dig and dig and see?

Okay, it's okay to laugh, but it sounded you were getting desperate and I don't blame you.

Let us know what happens, one way or another. Really hope this helps. :vs_cool:
 

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Discussion Starter · #17 ·
If I am reading it right, your solutions are just long linear gravel pits with no pipe taking the water at the house away. Don't forget those "linear pits" will be collecting the surrounding water too, which might saturate before water at the house even makes its way there. You want to transport the water away as quick as possible, not have it sitting like in a leach field.

No location, but if you have freezing, none of this works.

Rent a bobcat, regrade the entirety lower and sloped back to a small detention area that will percolate into the ditch.
Sorry for the confusion - Both of my ideas include perforated pipe to carry the water to a sump. Southern Oklahoma - no major freezing concerns -at least during wet season.
 

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Discussion Starter · #18 ·
Alex, love the house! Wish I could have that kind of brick out here in the Land of Shaky Ground. Alas, after a quake, it would become one of those funeral stone piles.

I'm going to make a slightly desperate out of the box suggestion:

That looks like a new tract, where the clay was compacted for construction. We had a lot of developments like that out here, with similar issues. One dude came in after he ended up with about 5 inches of water in his living room, because it drained the wrong way, and there was no good place to run the water.

So, out of desperation, knowing the top soil was compacted, he, me and a sturdy helper dug deep through the hard stuff on top and hit a softer more permeable layer below. That provided a place for the water to run through, and he was able to avoid further trouble after that.

It was not easy. It was masochism. It would have made a great punishment for someone you really hated. We dug about eight feet. I was 25 then; after, I felt more like 125. Maybe 126.

One reason we decided to do that horrible digging was I ran across a map of by US Geological survey at the library that showed soil types; it turned out that his soil had been graded over another type of dirt. So it was worth a shot.

So, maybe get someone with an auger out to your place to bore down a few yards and see what's there? Or check a USGC map for where you are? Or, just get or force some people to dig and dig and see?

Okay, it's okay to laugh, but it sounded you were getting desperate and I don't blame you.

Let us know what happens, one way or another. Really hope this helps. :vs_cool:
Thanks for the info, i can dig an exploratory hole and check it out.

This house was actually built in the late 70s.
 

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Discussion Starter · #19 ·
The contractor's quote actually included $1500 to regrade around the house. I may have him go ahead and do this only - i can come back later and drain the low spots into a sump.
 

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Thanks for the info, i can dig an exploratory hole and check it out.

This house was actually built in the late 70s.
It looks a lot newer because of the lack of vegetation around it.

Thanks for the info, and try, if you can, to be prepared to dig a deep hole.

You've obviously chewed on this a while, hope you'll succeed. :vs_cool:
 
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