French drain with no outlet

Is there ever a reason to have a French drain with no outlet, or with an outlet that's higher than the collector in the drain? This is in Florida -- north Florida, but still very sandy soil.
To make a long story very short, I've discovered that's what I have around my house. I had realized for a while that there must not be a down-sloped outlet -- that would require ground slope which isn't present. There's an outlet from the French drain around the foundation, but it rises at least a foot, making the outlet about the level of the top of the highest part of the French drain. To make it worse, the gutter drain Y-s into the French drain outlet about 6' from the house, in such a way that the gutter drain can feed back into the French drain, and probably does.
The French drain probably isn't needed anyway. Almost certainly isn't. But why it's there is part of the long story.
Anyway, if there's any excuse at all for this French drain, I'd like to know before I start shooting my mouth off. OK, before I continue shooting my mouth off.
Edward
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wrote:

Contractor that did the foundation probably just put it in without paying much attention to where it ended. Someone else then hooked the gutters to it. You're right, there is no temporary repeals of the law of gravity when it comes to water. You could dig up the of that goes out into the yard and bury it deeper with a some gravel at the outlet. But I would take the gutters off of it. Unless you make a really big drywell it will not be able to keep up and you will be running the water back around the foundation.
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wrote:

I have one built into my house with no outlet or sump pump. Think they just put it in just in case it were ever needed. My builder was a cheapskate, so maybe he had to do it according to code.
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Often on new construction they put in foundation drain systems to a sump pit or similar so that it's there and can LATER be completed, eg add a pump. It's easy to do at that time and then if you need it, it's there. Sounds like to complete this one would have required a pump and wiring, etc, so they avoided that cost unless it became necessary.
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Edward Reid wrote the following:

You didn't say what happens when it rains. Do you get flooding? Does the drain collect the water? Does the drain overflow? Maybe, the way it is installed is working well and that's why you think you don't need it. "Geez, it often rains heavily around my house and I never get a flood, so I don't really need this drain".
When asked which was more important, the Sun or the Moon, Professor Irwin Corey replied, "the Moon". When asked to explain, he said, "At night, it is dark so we need the Moon to see. During the day, it is so bright out that we don't need the Sun"
--

Bill
In Hamptonburgh, NY
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That really doesn't matter, he should not be directing the gutter down around the edge of the foundation and that's what it sounds like is happening. Even if that appears to not create obvious problems it's not a good idea. A lot of underground water flow can cause voids to be created depending on the composition of the substrate.
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That's right. A French drain without an outlet away from the building is not a drain, it is a gravel reservoir. These are used to *capture* water, not remove it. Gravel reservoirs are popular in desert climate landscaping, but I suppose they could be useful wherever monsoon rains occur. Reservoirs should not be located against a building foundation.
    Una
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Una wrote the following:

He didn't say it was up against the foundation, but maybe I missed that. He did say that the gutter (down pipe?) drains into the "french drain" (his words) 6' from the house. Could that mean the "french drain", or reservoir, or trench, is 6 feet away from the house? All we really know is that he doesn't think he needs it.
--

Bill
In Hamptonburgh, NY
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I think he made it pretty clear that he had a drain line around the foundation with the gutter connected in such a way that the gutter water was probably flowing back into the pipe around the foundation. And the thought by most was that is not a desirable arrangement.
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On 11/4/2010 10:34 AM, Una wrote:

I wish somebody woulda explained all this to the previous owner of this place... :^(
--
aem sends...

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OK, thanks. I like "no temporary repeals of the law of gravity".
The long story, based on the comments. Layout at
http://paleo.org/house/house.html
I did the diagram eight+ years ago while buying the house, but it's still correct in what matters here. I don't think it says, but the front of the house is about 100' to the road, 70' my property and 30' ROW (the paved road is butted against the far side of the ROW).
House was built in 1953. French drain and gutters installed in 2002 as part of my purchase, based on inspector's and contractor's recommendations. The seller was paying most of the cost, and I didn't pay a lot of attention to the details. Obviously should have paid more attention. (And in the end I may have paid most of the cost, as total required repairs exceeded the seller's contracted maximum.) The seller had been given the same report (same inspector even) when she bought the house three years prior, but had not taken any action.
Symptoms at that time:
1) Fungus on a few joists. Inspector could not say how old, but saw no change in three years.
2) Standing water or wet sand in the crawl space after rain.
3) Standing water at the south end of the house after a rain, pretty much covering the space between this house and the one next door.
Contractor, who came with multiple good recommendations, recommended a) the French drain, b) gutters, c) a low wall to protect the crawl space access door, and d) a berm in the back yard to divert runoff. (The crawl space access is at the SW corner of the house -- upper left on the diagram -- so water flowing from the back yard could enter easily.) AFAIK, the only evidence of water intrusion was on the south end and the south part of the back (west) side. Work was completed and we closed on the house. Though I paid less attention than I should have, I saw enough to know that they did install the French drain, and of course the other items are visible.
The French drain is against the foundation -- I didn't make that clear before -- on the west, south, and east sides of the original house (as marked on the diagram), about 110' total. The outlet pipe runs from the SE corner of the house to the ditch at the road, just off the bottom of the diagram.
Short term followup: though the berm was a good short term remedy, in a few months I completely solved the backyard runoff problem -- by doing nothing. Previous owner hired a "gardener" who came in with his lawn tractor and scalped the yard to within an inch of its life, then pulled out his leaf blower and took away the fallen leaves (the yard is shaded by large oak and sweet gum trees) and grass cuttings. I mowed as seldom as possible and at 3" height when I needed to, and never removed any organic material. Wonder of wonders, in a few months the ground was absorbing even the heaviest rain with no runoff at all (remember, this is Florida, very sandy soil). Neither the inspector nor the drainage contractor had noted this simple solution.
I got a remote-reading thermometer/hygrometer. Asked both the inspector and the contractor what RH was needed to prevent damage to the wood (fungus or rot). Neither could tell me. IIRC the inspector had noted that the wood itself was dry enough, just had this old fungus on it. Contractor basically said "I know how to dry it out, I don't know how dry it needs to be". He was proposing forced ventilation, which to me would just bring more hot moist air under the house, where it would cool since the house now has A/C (of course it did not in 1953, I think A/C was first installed in the late 1970s) and make it damper. I finally found someone who said the figure is 70%. My hygrometer shows that the RH is usually under 70% in the crawl space, and is only higher when it's higher outside. My conclusion is that the fungus observed on the joists probably grew 30+ years ago, before the house had A/C. No way to prove it of course.
I still had some trouble with water pooling, but it was clear that some of it was backing up from the road. The ditch had not been maintained, and water from uphill (north) was coming into my yard instead of staying in the ditch. After several calls, I got the city to pull the ditch and sod it. (The workers love throwing those sod staples, or whatever they are called, into the sod. I'm sure those do the job of holding it in, but I need a metal detector to get rid of them. Just yesterday -- some six or seven years later -- I found another one.) Since then, I've kept the ditch clear -- I learned that a narrow channel is better than a wide one, because the slope lessens in front of my house and the water drops its load of sediment if I don't keep it running fast. Neither the inspector nor the contractor noted the problem with backup from the road.
Long term followup: eventually the shingles made it clear they had reached end of life. Also had continuing problems with a "homeowner job" (a term I've come to use as a pejorative even as I continue to do some things myself) on the screened sun room (see diagram), including a valley with no slope. This year, had a new roof built over roughly the north half of the house, redecked the rest (was only 3/8 at most, not up to code), and metal roof put on the whole thing. Looks great, and only a single puncture through the roof -- got rid of two unused chimneys, used air admittance valves for two vents and ran the third through a gable, leaving only a skylight over the porch.
But I didn't plan adequately for replacing the gutters, and they didn't tie in well to the way we did the lower end of the metal roof panels, so I spent a good while figuring out how to add flashing and leaf guards to get all the water into the gutters and keep the leaves and acorns out. Finally completed that last week and got to test it the next day in a big thunderstorm. The gutters, flashing, and leaf guards seemed to work fine. Three downspouts were spewing water from joints, indicating blockage. The base of the downspout at the SW corner was a veritable spring, water gushing up from where the downspout entered the drain pipe. Not surprisingly, there was a puddle at the south end of the house. (Which verified that the original recommendation to install gutters was absolutely correct, since the flooding reappeared when the gutters didn't work, even though the backyard runoff and front ditch backup had been fixed.)
Checked the downspouts, only one was blocked, and that was above where it was spewing. So I started working with the drain pipe, which is that black polyethylene corrugated crap. Pulled out one downspout, reached in, and pulled out a 4' long hairball. (OK, root ball, but I have cats and it looks like a hairball.) Not enough to account for the symptoms, but told me that roots were readily invading. I had seen roots one other place, where a joint had been added later, so I wasn't totally surprised.
Experimenting, I found that putting a hose down one of the front downspouts got water flowing at the ditch, though it took about ten minutes to get there. Putting a hose in a back downspout, however, never got anything to the road, and the water was well above the top of the pipe, but the hose could not put out enough water to make it overflow. So there was a blockage along the south side, serious enough to prevent significant flow. Yet there was an outlet large enough to consume the input from an wide-open hose at less than 1/2 psi. Puzzled.
By this point I had decided, both from these observations and from reading various places, that the corrugated crap had to be replaced with PVC. So I started digging it up, no longer being careful to avoid making holes (and it's nearly impossible to dig the stuff up without making holes anyway). Got about half way from the SE to the SW corner, saw where I'd made a pretty big hole, and decided to test again. Water came spewing out of the hole. So I'd exposed the part with the blockage. Only took a minute to find a root as big as a finger growing into the pipe. Had to cut open 2' of pipe just to pull out the hairball, which ran 10' downstream and 4' upstream. After that, another test showed that water from the back flowed to the road, though it still took about ten minutes to get there.
(I still don't know why the drain was working before the gutters came off and were replaced, and not after. My guess is that it's a combination of it wasn't working very well before and that if I'd looked carefully during a hard rain I'd have seen some backup, that 3 months with no flow allowed the roots to grow tighter, and that some debris got in and plugged the remaining gaps before I got the gutters protected again.)
So yesterday I started digging full speed (which for me is not very fast) to expose the rest of the corrugated crap for replacement. I was about 6'-8' from the SE corner (going toward the road) when I noticed that I was hitting two corrugated pipes instead of one. I found that they were tied together in a tight Y -- both pointed toward the road, perhaps with the idea that this would mean one wouldn't back up into the other. Still more digging revealed that the one I hadn't seen before dove into the ground under the other. I didn't try to follow it, but it's surely connected to the French drain. There's certainly no other outlet from the French drain -- remember, I saw the work being done, so I know it's not draining into a reservoir, and although there's a little bit of slope, there's no place to hide a drain pipe and lead it to an unexpected location.
So slow-moving water could back up from the gutter drain into the French drain. Even some fast-moving water, especially with the corrugated crap. And if the corrugated crap is partly blocked farther downstream, a LOT of water could back up into the French drain. Possibly this has something to do with the long time for water to reach the ditch, though I haven't figured out any way to determine that.
So that's the background for my post last night. In eight years, no one has asked me for a recommendation on the inspector or the drainage contractor, so probably it will never happen. I'm unlikely to act to publicize what happened -- heck, I haven't even checked whether they are still around, and the worst I can make it out to be is incompetence, not fraud. But still there's this nugget in my brain that wants to make sure I've got it right in case someone asks.
As for my belief that the French drain was not needed ... well, obviously I have no way to remove it for testing. The fact that the situation seems to be under control even though there's no effective outlet weighs strongly in my mind. Of course, since the soil is sandy, it's possible that the French drain is acting as a reservoir to get the water to the bottom of the foundation to percolate, instead of being against the foundation wall. (The foundation wall is brick, painted on the outside. I think the paint was there before the French drain was installed, but I'm not totally certain.) I know, as described above, that the French drain doesn't solve the puddle -- blocked gutters alone re-created that, even with no backyard runoff or backup from the ditch.
As for installing a French drain with the idea of adding an outlet or pump later ... well, I've explained that I know that was not the case here. But in this environment, a French drain with no maintenance is just a mass of roots anyway. If I dug up my French drain now, I'd probably find solid roots in the pipe -- after all, that pipe has to have holes in it, which are invitations to the roots.
Now, aren't you glad you asked?
Edward
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Hi Ed,
As I said before, what you have in effect is a reservoir, not a drain. The intrusive root balls are proof. Also, French drains should not be used with gutters and downspouts. They are used to drain water *from* the ground, not introduce water *to* the ground.
One reason you had root balls plugging the drains was that until you put the new roof on and put screens on the gutters, oak leaves and Spanish moss etc were going down into the drain and being snagged in there.
Personally I would redo the French drains with PVC as you are already doing and remove the gutters from the roof. It sounds like your sandy soil is fully up to the task, with assistance from the French drains to remove excess, now that you have fixed the surface runoff from your west neighbor. If you do this, the ditch won't back up quite so much because your property will be draining less into the ditch.
With so much water and your layout, you could also have a spectacular rain garden and/or koi pond in the front yard.
    Una
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On Nov 4, 9:23pm, snipped-for-privacy@att.net (Una) wrote:

Why on earth would you remove the gutters? The first rule in getting rid of water is to correctly deal with the roof water by channeling it away from the foundation. Makes no sense to change it so that rain water falls from the roof to the ground and then try to deal with it there. In addition to all the addional water at the foundation, he would then have potential erosion problems from the falling water too.
Bottom line, deal with the roof runoff and french drains seperately.

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Roof gutters and French drains are alternative, not complimentary solutions. Roof gutters are a maintenance nuisance, and they aren't very satisfactory in climates where rainfall has a monsoon pattern (short, heavy showers).
    Una
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On Fri, 5 Nov 2010 15:29:33 -0600 (MDT), snipped-for-privacy@att.net (Una) wrote:

I hear you, but in my case it's clearly essential to get most of the roof runoff away from the house. Or to look at it another way, the French drain clearly isn't moving the water away, so I'll do it with gutters. Actually if there were evidence of water moving under the surface toward the house, the two might indeed be complementary. But I agree that in this case, the French drain probably duplicated the function of the gutters.
I just don't believe there's enough slope to move the water away from the house once it hits the ground. If it goes into the French drain, it's something like 18"-24" underground. Even if the exit hadn't been installed uphill, what was the choice? A leach field? The bottom of the French drain is possibly lower than the ditch, and certainly not enough above it for proper flow. It has no place to exit. The gutters at least let me capture the water at the ground surface rather than below it.
Yes, the gutters require maintenance. I hope to reduce that by installing PVC pipe to drain the downspouts to the ditch. That should greatly improve the passage of leaves, and make it possible to root out the pipes should they ever clog. (I will install cleanouts.) The odd way the gutters join my roof means that it's difficult to raise the leaf guards for cleaning, so what gets through the guards will mostly go down the downspouts. But overall, I'll accept that I have to maintain the gutters, not ignore them. I also have to blow the leaves off the roof regularly anyway -- it's only a 3/12 slope or a little less, so even with metal, the leaves don't all blow off by themselves. There's a large live oak and a clump of bamboo that drop a lot of leaves on the roof.
And the French drain would probably need a lot of maintenance too, were I to depend on it. I don't plan to expose it to find out, but I expect that I would find a lot of roots in it already. At least I can see gutters, except for the drain pipe, and know what's wrong.
I thought "monsoon" referred to seasonal rainfall variation, not daily or hourly, so I'm not sure what you're getting at. Rainfall in my area varies from 4" to 7" average per month over the course of the year, so there is no particularly wet or dry season. It is true that much of it comes in thunderstorms, often at a high rate. (A couple of years ago, during Tropical Storm Fay, some places in the area got 17" of rain in two days.) I accept that the very heaviest storms might overflow the gutters (I used the small ones), but that's OK. A little water on the ground occasionally won't hurt anything here. I just don't want it there consistently.
I love watching the rain drip from the edge of the roof. I just don't like watching it form a pond at the edge of my house.
Thanks again,
Edward
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snipped-for-privacy@att.net (Una) wrote:

I agree. What I am saying is that a French drain would serve well for that. The thing you have, that was supposed to be a French drain, is not one. It is a long skinny underground reservoir.

They put corrugated plastic 18-24 inches down? No wonder the job went over budget. That is far too deep. Good news is, it means you have a lot of room to raise the drain tile to nearer the surface under the drip line, and have a good slope down to the conduit leading away from the house. It would be less work though to abandon the underground stuff and build a ground surface channel from the downspouts to the ditch. You can make the channel look like a stream bed, if you like that sort of thing in a garden.
    Una
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On Sun, 7 Nov 2010 09:02:43 -0700 (MST), snipped-for-privacy@att.net (Una) wrote:

Some slope. Not good slope. This is Florida ;-) ... north Florida, but still Florida. The state whose high point is about 350' about sea level. I'm happy if there's a downslope at all.

I like the idea, but not in the short term. Don't know if it could work in this yard at all. And the channel would still have to be solid material, not soil -- not here -- would have to be concrete, PVC, rubber lined, some such. The sandy soil and minimal slope limit what can be done. And it would take a long streambed to pick up all the water from the back side gutters.
Edward
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