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Slopes, drains, driveways...oh my

Posted by eaton72 NC, Zone 8 (My Page) on
Sat, Aug 13, 11 at 14:13

We've been reading a lot for the last year and need advice specific to our situation.

We had a new home built this year, our forever home. We worked with the landscaper to best grade the lot to include bringing in close to 1000 yards of dirt. We are on a natural slope that backs up to protected wetlands, woods and a drainage easement. We are on a cul-de-sac lot with no neighbor to our left or rear; and a neighbor to our right that sits about 6-8 feet above us with a slope between our yards. Our back yard has a gradual slope and our left yard has a sharp slope. There are not really any flat spots in our sides or back yard. We will post pictures soon to give a better understanding.

We are having issues with drainage around the house and the driveway. When it rains or the irrigation system run, we have the runoff from our neighbor coming down the slope. We also have our own runoff from our gutters and irrigation system.

On the right side of the house by our neighbor slope, we are currently installing an underground drainage system with 4" corrugated pipe connected to the downspouts, tying into a 9x9 catch basin which is connected to a pipe that is buried down the backyard with a pop-up emitter. We've got 1/2 of this project completed, hope to finish the remainder today weather permitting. The pipe will be slightly mounded over to create a berm to prevent the slope run off from reaching the foundation of the house. We had considered creating a dry creek bed, but changed our minds.

On the left side of the house, we are not sure what to do. I am attaching a video of this issue, taken today. Our driveway has an extended parking pad. The driveway has a valley. When it rains, two gutters feed into that valley plus water travels across the yard to feed into that same low spot. It hits the grass and has no where to go. A big puddle forms into the yard and backs up across the driveway "valley". Running pipe from those gutters is not possible, as they would have to run across our driveway and sidewalk. We need advice for how to best disperse that water away and down towards the wetlands/easement.

We've got a mess on our hands. These are the two most pertinent issues at this time, but there are plenty of other problems we'll have to tackle.

Thank you for any insight or advice.

Here is a link that might be useful: Driveway rain


Follow-Up Postings:

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RE: Slopes, drains, driveways...oh my

You really have to be on the scene to asses this accurately but if I had to guess it would be the the 1000 yards of dirt that caused the problem.


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RE: Slopes, drains, driveways...oh my

Here is a slide show of photos walking around our house...
We've got dense clay soil that does not drain well.

The big bed to the right of the house is where we have been working on the underground drainage system. We're planning to plant ground cover (liriope, phlox, daylilies) on the slope b/w our house and the neighbors'. The large tripod shaped tree at the back of the bed appears to have died or gone into shock/early fall. This became noticeable mid July when the leaves suddenly turned brown. We only moved in late June.

The steep slope coming from the back patio is difficult to mow and will likely be a project for a later date.

Here is a link that might be useful: Drainage Concerns around the yard


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RE: Slopes, drains, driveways...oh my

Well those 1000 yards are there, and they probably aren't going away. I'm wondering if you could have your gutters rejigged so that your downpipes can be put somewhere else. That would be the easiest, but only partial, fix.

You don't say whether your back yard slopes up or down but "drainage easement" and the video suggest downward, is that right? In that case, the water must have been intended to go down that slope to the "drainage easement?" The intent would be to use it for drainage.

If the water doesn't go where it should, maybe have your landscaper back on a rainy day and discuss how they can amend the design to resolve your problem.

KarinL


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RE: Slopes, drains, driveways...oh my

The dirt created slopes versus drops.

The dirt was necessary and certainly isn't going to be dug up to create steeper grades.

The back yard slopes down away from the house. Everything flows towards the left back corner ultimately. The drainage easement is for the storm water runoff from the street.


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RE: Slopes, drains, driveways...oh my

Reconsider the dry creek bed or a french drain.

Reduce the amount of pavement in your driveway. There's lots of ways to do it, some more attractive than others.

Read up on rain barrels.

Those are my suggestions.


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RE: Slopes, drains, driveways...oh my

Just for the record, and in case any other prospective posters are reading this, I find it really difficult to work with photos that are posted in slide show format. Some photos you really need time to study, and the slide show never allows that, forcing the viewer, if they are so inclined, to watch the slide show again and again and again! Please, if you can, post to a photo album on a photo hosting site so we can study the photos at our own pace.

I would be interested in hearing what your landscaper has to say, but quite honestly, I wonder if you should be consulting a soils specialist or civil engineer - or did you? You could take steps to enhance absorption of water, for example, which might happen if you terrace that slope a bit or if you follow the ideas of Pinusresinosa, but I'd be concerned about site stability if you do.

Back to Inkognito, who can say much with few words: probably a problem for on-site specialists, not for internet generalists.

KarinL


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RE: Slopes, drains, driveways...oh my

Strange.

Strange that a lot with this topography was selected when a walk-out basement was not intended.

Strange that the house was not reversed so that the garage/drive would be on the high side of the lot.

Strange that the finished floor was not slightly higher to move the driveway water to the street.

Strange that so much money was used to import all that dirt that pushed all the vertical drop to the rear of the property creating a slope you will hate to maintain.

Strange that development is pointed at discharging all the rain water quickly, then paying for the water used by an expensive irrigation system.

Strange that a adequate grading / drainage plan was not done before the house construction started.

Strange that a plan was not done after house construction, when it should have been obvious that there would be problems.

Strange that drainage mitigation is underway and there still isn't a plan.


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RE: Slopes, drains, driveways...oh my

From the slide show-it is hard to take in all the info when you can't study each picture-the house next door is above yours and there is nothing to keep their water from your yard and house. This should have been addressed before building. My BIL has the same situation brought on by neighbor's re-landscaping after 16 yrs and there is no where near the slope you are dealing with. They have had to put in a berm and drains between their house to fix it.
You might be able to do a terrace with a drain behind it and slope your yard away from your home toward the terrace with another drain at the foot of it. This is what they have done at the back of their home due to runoff from a very steep natural area. They got professional help/plans and did part of it themselves.


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RE: Slopes, drains, driveways...oh my

Thank you for your time, all. We've seen a lot of great advice given here over the last year. We're sorry for asking for thoughts on our own situation and for the inconvenience of a slide show which we thought we be helpful.

Strange - Construction in our area does not include basements due to the water table being high. The reverse plan was the original plan, but was not possible due to reasons stated by the foundation engineers. There was not a significant expense on soil being brought in, most was free due to swimming pool installs in our area. We'd be happy to share the photos of what the grade was like before that dirt was added, but I doubt it'd matter. The lot was heavily wooded and has a natural slope due to the wetlands at the base, as do many others in this area. Our concern is getting rain water down there without ir pooling near the right of the house or at that section of the driveway. We have a well for our irrigation system; there is no paying for the water itself. And until we started getting heavy rains, there was no obvious drainage issues. Our builder is not delinquent here.

We'll consult elsewhere regarding these issues; and be sure to only ask about less significant topics here. Again, we thank you for the time you gave to our post.


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RE: Slopes, drains, driveways...oh my

Maybe getting a new topographical survey would clarify more precisely the origins of the water issues on your attractive property and suggest possible solutions. One caveat though. To maintain the integrity of the nearby protected wetland, there will most likely be prohibitions of some type as to the added runoff or possible interference with the prescribed buffer zone.

I would suggest asking a local expert. Good luck.


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RE: Slopes, drains, driveways...oh my

I'm sorry that you're taking offense; that's not necessary at all. My point about the slide show is because several posters have set their photos up this way lately and I'm getting dizzy :-) It's a form of technological advance that does not help.

There are two issues at play here. One is that if you are asking people for advice, they need a certain amount of information. Most of the people here are pretty conscientious - even if, like me, we're not professional landscapers, we are pretty careful not to give advice that can make situations worse or create further problems. In order to to maintain that standard, we need to understand the problem thoroughly, which includes having good photos and being able to study them, and in this case, the second issue: understanding why this problem was created in the first place. And it was created - you may believe that there were no obvious drainage issues until you started getting heavy rains, but water flows downhill and you've said you have clay soils (and now a high water table). As such, any builder, landscaper, or engineer who was involved should have foreseen that water flow from your neighbour would be a problem, among other issues. But sometimes the construction choices made were made for good reason, and it helps us to understand what those reasons were - for instance, you've pointed out that the drop-off was initially much worse. The fact that you don't have a basement is also important information, because the pictures don't tell that - is it a crawl space then - or something that does not need to be kept dry?

The other thing we need in order to be helpful to you is feedback to what we say and also answers to whatever additional questions we feel we need to ask. You have responded on some issues, but not on others. My point as to whether the gutters can re rearranged to discharge to the back of the house stands unanswered, and it's also not clear to me whether that would help because the video doesn't show the water pooling as clearly as you might expect it to. As does the question of what professionals you have consulted so far, and what their views have been.

The possibility does exist, and we've seen it here before, that your house was very poorly sited and that litigation might be more suitable than mitigation. You've stated pretty clearly that you do not think that's the case, but I hope you can appreciate that based on what you've shown and how you've described the water issue, the average observer would be led to think in that direction.

I hope you'll engage further so that we can understand your problem better. Even if you do end up needing professional consultation, people here may be able to help establish the range of options or questions you should ask.

KarinL

PS: for me in particular I am always concerned that I not contribute to a situation like the one that set up a tragic mudslide in my area a few years ago. Story linked below. Not that you have houses below, but I wouldn't want to hear of your house taking a slide either.

Here is a link that might be useful: North Van mudslide story


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RE: Slopes, drains, driveways...oh my

Karin, I think the OP found offense with my post, not yours. I hesitated to make that reply since it held no value to him. I'm really speaking to those who might read this thread and avoid the mistakes in their future projects. If I was harsh, it was to make the point that the entire property should be considered before home construction begins.

Actually, I liked the video slide show presentation. I let it run through the first time and I quickly saw a thumbnail of the material covered. The second time through I hit the pause button on each photo to get a more in-depth picture of the situation.

Most of you don't live in a climate like North Carolina or Arkansas where I live. So you may not understand the significance of what was said.

"Construction in our area does not include basements due to the water table being high."

The same is generally true for Arkansas. Ground that is bone dry during part of the year can have a substantial underground spring in wet periods. And in warm climates wet basements or crawl spaces can result in dry rot or termites. There is not a single competent homebuilder in my area that will build a hole in the ground basement. The exception to this is a walk out basement on a lot where protective drainage can surround the home and be discharged to an area lower than the house foundation. This usually requires a down sloping lot of 8 to 12%.

In the upper south, a walk out basement cuts the energy costs for heating and cooling on a per foot basis. Per foot construction costs of the home are also often reduced. For this reason, down sloping lots typically sell for about 10 to 20% more than flat or up sloping lots. What I saw here seemed to be a miss-match of house to lot.

On placing the garage / driveway on the high side of the lot ...

Here in Arkansas, and I suspect in North Carolina, the top 18 inches of soil never develops the level of compaction of deeper soil that has not been disturbed for millions of years. Thus below 18", you will usually find soil to have a greater load bearing capacity more suitable to garage slabs. Put the garage on the high side with a cut to hard soil, and the step-up to house finished floor gives the needed height above ground for the crawl space on the lower side of the lot. Do the reverse and you must either do an expensive compacted fill for the garage slab or make a substantial excavation to create a crawl space, one that is well below natural grade (not good). So for the house presented, there is the neighbor's water flowing to the foundation where the crawl space is at a much lower grade than the outside grade.


Drive through subdivisions here and for lots with more than a 1 foot side slope, it will be the rare exception to see a garage on the low side of the lot.


It is much cheaper to anticipate and prevent drainage problems than it is to fix drainage post construction. And it's much cheaper to build walls to avoid the slopes that homeowners grow to hate if done before or with foundation construction. It's a big mistake to begin construction without a detailed grading and drainage plan done by someone that knows what he/she is doing.


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RE: Slopes, drains, driveways...oh my

Beautiful setting. I hope you can resolve the problems you're having.

Re the slideshow: to spend time on an individual picture just click on the PAUSE button.


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RE: Slopes, drains, driveways...oh my

Not an expert like others here, but we have some similar issues here-steep hill in backyard, neighbors' properties drain into ours and we have a driveway that also floods with heavy rain.

If possible, I would contact the builder because the driveway had to have been graded incorrectly, no matter what he says. It should drain away from the middle and there definitely shouldn't be a valley. Ours is more than 50 years old and we are considering using permeable material when we redo it, but we will definitely have it graded to drain into the yard rather than pool in the driveway itself! Everyone we have contacted said that was a given when putting in a driveway.

I would also spend a good amount to landscape and terrace those slopes if budget allows and make sure the builder didn't put in drainage from neighbors that allows runoff to go into your yard. One of our neighbors had landscaping done and the contractor aimed her flexible black drain pipes right into our yard. I pointed it out to her and she had them redirect them into her yard. We have another neighbor who struggled with standing water in his backyard and tried all kind of drainage systems until he finally settled on a cistern that sounds similar to what you are getting. It worked like a charm!

Oh, and I think you were right to decide against the dry creekbed. We had one put in and it is a mess with leaves and debris that need to be cleaned out on a regular basis.

I hope you come back to read these posts. Many of the folks here are pros who offer their expertise to others for free which is quite something I think and well worth consideration.

I agree that you have a pretty home and that yard will be something once you landscape it. Don't give up on this forum or any of the others. You could also check out Hillside Gardening, Trees, and Shrubs forums for ideas.


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RE: Slopes, drains, driveways...oh my

Had one other thought as I walked the dogs the other day. It might help to add an extender to your downspout to direct the water away from the problem areas. We use those as do most of our neighbors, I noticed!


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RE: Slopes, drains, driveways...oh my

Looks like I'm coming into this conversation late...maybe too late. But if not, here's my 2 cents...

easton72, I looked at your pictures and watched the video. Clearly, you have a ready place for water to go. No problem there. So your task is simple; make sure that nothing gets in its way. On the right side of the house (it's hard to tell from the pictures, but it looks like it might be a little flat across the front of the house leading into the swale (valley.) The solution to that is making the swale more pronounced or in other words, a little deeper. I'm only talking about an inch or 2 or 3. This must be blended into the area where it's collecting water. Wherever water lands, there must be some kind of downhill direction for it to go that is away from the house...at least for a few feet. This "deepening" must continue to the point where water will continue to run downhill freely. Depending on the actual grade, if it's very flat, it could mean shallowly "scraping" out an area 50 or 100 square feet or so. (Nothing a couple of Canadians with shovels couldn't take care of in a quick hurry!) I hope I'm not describing it so that it sounds major, it's not.

To check the conditions, place a 4-level at the foundation, perpendicular to it, at grade. Hold it so that it reads level. How much fall shows up at the other end of the level? I would want at least 2 inches of drop within 4' of horizontal distance (as measured away from the foundation.) A little more would even be better. Follow any path the water might take as it runs away. If you meet a place where it is penned in or can't "decide" which way to go (too flat,) then it must be dug out. As long as water continues in a direction that is acceptable and with constant fall, there is not a problem.

On the left side, where water is puddling at the edge of the drive (looks like you have it marked with a brick or something) the driveway itself appears to pitch to the edge. It looks like water is only being blocked by sod that is a little to high...and the brick marker itself. If you reduce the elevation of the sod by about an inch in that area, I think you would have resolution. Have it end up so that about 1/2" vertical of the driveway edge is exposed for about 3' of length centered on that swale. (Running the truck tires over it a couple of times might do the job.) If you expose the driveway edge a little too much, it's no worry. You can always add a little dirt back on top of the grass later.


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