French drain help.....

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My neighbors yard is higher than my yard by about 3'. His property slopes away from his house and towards my house. The grading around my foundation on that side is not correct (i.e. its pretty much level) so the water from his property ends up against my foundation during a bad rain (like what we just got in the Northeast).
Aside from correcting the grading at my foundation, I wanted to add a french drain. It would be about 10' from my foundation, basically at the low spot between his yard and where the grading from my foundation would end. I also have 2 downspouts to drain out on that side of the house, and I figured while I have the Kubota I might as well bury the downspouts too.
A couple questions......can I use the same trench for the downspout drainage and the french drain? I would keep them as separate pipes, but I wasnt sure if the downspout pipe would interfere with the correct operation of the french drain.
Also, any recommendations on fill material? We have what seems to be normal soil for the area........definitely little to no clay content. I was thinking just normal 3/4" gravel from the local stone company. 2 or 3" in the bottom of the trench, followed by 4" drain pipe (was going to use the PVC stuff, not the black flexible stuff), followed by enough of the same 3/4" gravel to fill the trench to within 2" of the yard, followed by a layer of sod so I dont have to look at the gravel forever.
Does the plan seem OK? I know a lot of people recommend different fill materials, figured Id ask what everyone thinks.
Thanks! -Chris
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...
Is this the natural/original grade or was the house next door built after yours and the drainage changed? If the latter, it may be possible to require the neighbor to resolve the problem.
Guy bought empty lot next to us and tried the same trick -- finally took a letter from the lawyer to really get his attention, but he had to rearrange the initial idea for his driveway drainage to not impinge.
It depends on local zoning rules/requirements and what the local attitude towards enforcement of same, but in general it's a tenet that new construction can't change runoff to the detriment of existing.
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Nope the houses were built at the same time. After chatting with my neighbor he explained to me that the previous owner (of my house) actually built the side of our house UP to what it is now (at best, it might be a 4" rise over a 20' run from my neighbors house) As it is, I cant go up very much more, the siding of the house is about 6" off the ground now, didnt want to get the yard within 4", so I can add another 2" height and Ill have to grade it to a steeper slope, but I dont care.....cant use the yard in that area anyway, and its more important to stay dry.
Id love to force someone else to fix it for me :) but alas Im on my own with this one (unless I choose to hire it out, but the machine is coming to my house for another project, figured Id just do it myself if I could).
-Chris
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says...

Sounds like you need to excavate a swale, and slope upwards from the swale towards your house. You can place a french drain in the lower part (valley) of the swale.
Banty (doing that myself)
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In that case, I'm w/ Norminn that what I'd go for rather than trying the french drain as the only techniqe is to build a berm between to deflect the runoff away from the house and if needed in addition, a gravel-bed channel to carry the runoff. That was actually a significant portion of the solution between myself and the neighbor I spoke of before.
If you try the french drain, there's a lot of water capacity needed and from afar it's hard to advise on how much or what would be needed. Depending on the slope and what soil and weather conditions are like where you are, it's possible simply a shallow channel can be seeded w/ grass and/or ground cover and be able to hold.
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Thanks for the suggestions.
The only reason I immediately thought "french drain" was because I figured (possibly wrongly) that it would have more water carrying capability.
Seeing as how I need to re-grade from my foundation, I can probably re- grade to a point 10' from my foundation, and then just have a drop off of about 3" or so. That would qualify as a "swale", but I wouldnt be able to run that ridge all the way to the back of my property (we do use the back yard on that side of the house). It would re-direct the water but eventually Id run out of ridge/swale, probably not far enough away from the house. However, I might be able to gradually lower the "ridge" into flat ground.
The amount of water we get usually is not an issue. We've had good size downpours already this year and not had a problem. During extreme circumstances, however, it becomes one. Extreme being 5" of rain in a 10 hour period (this weekend) or 19" of rain over a 9 day period (2 years ago). I went outside during the storm and could see the issue.........water was puddled right up against my foundation. Since water doesnt travel uphill (very well anyway :) ) correcting the grading at the foundation would probably correct 85 or 90% of the issue. I will definitely put a gravel covered channel at the bottom of the new grading (does that make the new grading a "swale"? or does a swale have to involve some sort of ridge that the water would run up against?).......while i was digging, my thought was to drop pipe into the gravel channel, so that it would help the water that does go in, get out faster. This "french drain" would then be the "first line of defense" for the water, and the foundation grading would be the second line........presumably the foundation grading being the more important of the two.
-Chris
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My reason for suggesting putting in some kind of landscape feature with a berm is that a a rise of a couple of inches might be enough to divert water that runs down from your neighbor. It would be exceedingly easy (on a normal sized lot) to lay down that much soil and keep it in place with sod or other plants. You would need to figure out where the water will go if you divert it.
We had lots of small problems in the lawn at our condo that I fiddled with. One was that after many years of running edgers along the same line, there was quite a hump of lawn along the building with a ditch next to it. In some places, it had exposed sprinkler pipes that would then get run over by the mower. In some places I just hit it with a strong stream of water - the grass stayed in place and the dirt went into the ditch. Wasted some water :o) I found concrete doughnuts 6" down, with no protection of sprinkler heads that hubby had to keep fixing. Landscape problems sometimes have simple solutions.
We also had a great deal of erosion behind our seawall - not visible in places because the sod was so healthy it covered the tunnels between the washouts - kind of dangerous to walk on. That was fixed by putting some filter fabric behind the weep-holes in the seawall, gravel behind it, and filled up with soil.
You may need French drains, but that is a major project. If soil is saturated, from continuous rain, they might not do any good, but I really don't know.
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lay landscape fabric first, then a layer of rock, then perforated drain pipe, then more rock, layer of small rock, landscape fabric, then cover with dirt.
dont install drainpipe without landscape fabrick or dirt will soon infiltrate and clog drain lines.
you could create a natural catch basin, add landscape drain and seperate line to daylight somewhere.
that way excess surface water has a place to go.
its best to overbuild this system or otherwise in 5 or 10 years you will be doing it again.
a little extra cost now can save lots of work later!
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Overbuilding is good :)
But I didnt want to go too crazy, in case something I add effects something that is already there (i.e. draining the gutter runoff into the same trench as the French drain....would the second pipe from the gutter interfere with the operation of the french drain pipe).
The french drain pipe will be open to daylight, about 60' away, down a hill. So I should get good gravity flow. I might be able to use the berm idea for some of that 60' run, which would help keep the water over the french drain area, and give it a chance to get out (in the case of torrential downpours). The only question I have at this point is if I should tap the gutters into the same pipe, run another pipe in the same trench, or run a separate trench for the gutter pipe.
BTW, what depth are you suggesting for the french drain? I was thinking 24" at its highest....with a pitch of 1/4" per foot, the depth where it sees daylight would be about 40" or so. Could the pitch be lowered to 1/8" per foot? I think I saw that suggested, but again, overbuilding is better than underbuilding.
-Chris
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well, you can use the same pipe for the landscape drain and the downspout drain, as long as it's big enough. for both. To figure that out, you could estimate the maximum amount of water you expect to have to move per minute. Or you could just go with a 30" culvert, so you've got a big enough pipe for wild animals, and small children, and a weapons cache.
In any case, bury it deep enough to be below the frostline, if any.
You'll want to build a spreader dam or rockfall or something at the outflow, or it will build you a nice gulley in a year or so.
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DONT USE THE SAME PIPE! pipe is cheap, better they be kept seperate.
why add more water to a french drain system, it just lessens its efficency.
one inch of water over a whole roof can be thousands of gallons of water
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No problem using separate pipe. The issue I was thinking would be the separate pipe in the same trench causing a problem with the water getting to the french drain. I suppose its no
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Actually didnt think about the frost line, but I was planning on having the downspouts as they are now, but i would put a drain grate at the bottom of each for them to flow into. If for some reason the drain pipe froze up, I could always just redirect the downspouts farther away.
I *think* the bucket size on the mini-loader is either 18" or 24" wide. Would 18" be wide enough for 2 4" pipes? Obviously the pipes would fit, but would they be too close to each other? For the downspout drain, Id use regular PVC (non-perforated) because the perforated pipe in the same trench should do the job of the french drain. Although........would 2 sets of perforated pipe be better than 1 in this case? Im not sure.
-Chris
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Well, I suspect that If you're using a separate pipe to handle the roof water, that pipe shouldn't be perforated. You use perforated pipe if you're trying to either collect water, or distribute it, and you don't want to distribute water into the the trench, because there's already too much water there, and you're not using that pipe to collect water, because there's a different pipe doing that job.
You might consider talking to a landscape architect. I'd think this would be a fairly well-studied problem so it shouldn't take days of consultation to come up with an optimal solution.
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Its a possibility.......I could take the 2" extra rise than I can get without hitting the bottom of the siding, and basically make a ledge out of it......2" of soil out 10', would create a decent height berm between us and the neighbors. French drains are a lot of work...the only reason I even thought of it is because I have the machine coming for another project (son needs a swing set!), but since it will be here for almost 3 days and 8 machine hours, I figured while I was at it I might as well fix some things around (literally!) the house.
I like the berm idea.......the issue I have with it is where it will run off into my yard. My back yard is basically a hill, my plan was to divert the water back there to let it run right down the hill. It would be a pretty long berm :) its about a 60' distance. It would be a long french drain as well, but that would be level with my yard, and less intrusive. In the area next to the house (where my neighbors water flows), I might do both the berm and the french drain, gradually lowering the berm into the level of the rest of the yard.
-Chris
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It's not that hard to fix, as long as you have someplace you can dump the excess water.
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I've never built a French drain. Can you terrace the soil on this side of the house? Say, in tiers and then plant landscape plants? As to the drain, a landscape show I watched recently built a small one. They used a screen (landscape type) along the sides, to prevent silt into the gravel. The gravel was "river rock", the round stone edges allowed better drainage.... The screen fabric was then folded on top of the gravel. They went three feet deep for just a smaller area than you mention.
Good luck.
-- Oren
"If things get any worse, I'll have to ask you to stop helping me."
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Unfortunately it wouldnt be easy to landscape the area. There is a window well on that side (the well itself was causing some of the issues), and I cannot go much higher with the ground level before it hits the siding on the house. If I wanted to tier landscape, Id have to dig out quite a bit of soil to make a low spot, and that would probably make things worse (water would just flow faster from my neighbors side).
Re-grading is my best option, the only question was if (how) to put a french drain at the low spot between our yards.
River rock you say? Did they use it for the whole drain? The price of river rock vs .75" gravel here is astounding........80.00/yd vs 26.00/yd. I estimate Ill need 7 yards total. The local stone co. suggested the 3/4" (non river rock).
-Chris
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When I heard the guy say river rock I was surprised, because of the cost. It was only .75" or so. The drain was only 2X2X3. I thought the point of the smooth edged rock made sense, so to facilitate drainage and the point of using fabric to reduce silt in the drain. As I mentioned, never built one :-) -- Oren
"If things get any worse, I'll have to ask you to stop helping me."
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I used 2" & 3" rock in most of mine and just covered the top with 1's & 2's.
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