I’ve got serious drainage problems with the house I’ve recently purchased. I think the backyard drops quite a bit from the end of the deck to the fence. I would like to install a french trench drain around the house in addition to solid pipe drainage from the gutters.
However, also on my list is getting several yards or truckloads of dirt to bring the backyard up to grade. It is sufferring from years of erosion.
Which one of these two tasks should I address first? I think I should put in dirt–but I don’t want it to disappear while I wait a bit for it to compact. I don’t want to install a French drain and then bury it two feet further down with fresh dirt–which would defeat the purpose, I think.
While I’m at it I thought I could install a few underground rain barrels / mini-cistern that could provide water for landscaping purposes. Does anyone have any positive experience with a simple pump that can be used for this purpose?
I know I just submitted several questions in one feed–sorry for any confusion and thanks in advance for the advice.
Replies
A few thought....
Don't connect your gutter/downspout drains to a house perimeter drainage system. It's a good recipe for disaster.
Once you get some dirt in there and get it regraded, the best way to stabilize the soil is to get something growing on it - probably grass. If you feel that it needs to be compacted, the machine that you use to place the dirt will compact it enough. Even if you place it by hand, it still needs to be stabilized asap.
Regarding the french drain you are proposing, is that to go right up next to the house or is it more like a curtain drain that would kinda go out in the yard? Do you have moisture issues under the house?
How steep is this site? A pic might help. If you decide to take one stand back 75 or 100' from the house.
I discovered a moisture issue under the house about two weeks prior. During the home inspection, we could not access the crawlspace due to poorly designed ductwork orientation. Since the purchase, we have installed an additional access door to the tight crawlspace beneath the house. I found mold in both corners on the front of the house. This is exactly where the gutters drain the roof into flowerbeds in front of the house--the water seeps underground (and downhill) underneath the front curtain wall. Or through it--not entirely sure. There is moisture in these corners and in one other area. Otherwise it is bone dry throughout the rest. This has been going on for who knows how long, and as a result the house tilts towards the back about 5 to 6 inches from the front door to the back door. The house might only be 50 deep.
As for the grading of the yard, from a gate near the front of the house (on a side where there is a severe runoff problem) the ground drops about 16 inches before reaching the back corner of the house. It then drops another 24 inches to the back fence--which is probably about 50 feet further. These are rough guesses on the distances, but I did measure the drop with some accuracy.
I also live next to a city drainage ditch/creek. Lined with rip rap, that has washed away over the years. It is normally about 10 inches deep by 8 feet wide. When it really rains, the water triples in width and gets about 12-15 feet deep--these are also guesses. The point is, it's impressive. The back corner of the yard is the worst, it's near a slight bend in the waterway, which leads to erosion. Near the front of the lot the problem is minimal. This explains the drop from front to back--all the water landing on this lot is headed in the direction of the back corner. Being the lower house compared to the two adjacent lots (one on the side and one against the back) all of the water runs through the back part of the yard to get to this ditch. I plan to have the water surface/empty from this system somewhere right next to this ditch. I won't have the gutter drainage connecting with the curtain drain, simply might have the two share a trench to save my back. I believe I saw an FHB article outlining such a process.
I'm also considering consulting outside sources locally so I don't overlook something obvious and cost myself more in the long run.
I did talk with someone who pointed out that my problem is mainly with surface water, and therefore a french trench might not be of great benefit. They suggested something akin to a dry creekbed as an alternative to give the water a path that would not further the erosion.
What would be a proper grade for such a slope? I also have to factor in the chain link fence that is almost serving as a 10 inch retaining wall. Just beyond the fence the level drops about that much before it begins a steep slope (greater than 1:1) down to the water. It might drop 15 to 20 feet over 10 to 20 feet width. I may have to address this slope before I address the yard--I don't believe the two are mutually exclusive.
Thanks to all who provided insight into this project. I'll try and get pictures up first part of next week.
There are some things in your descriptions that I didn't understand, so I'll wait for the pics. Please take at least some pics standing far away from the house.
In the mean time I'll hit the high points...
It does indeed like you have some extreme topology to deal with - a revene is near your house, although most of the yard drops only 2 or 3 feet so the area around the house is not that bad.
>> I found mold in both corners on the front of the house. This is exactly where the gutters drain the roof into flowerbeds in front of the house--the water seeps underground (and downhill) underneath the front curtain wall. <<
Get some black flexible pipe and pipe the water away from the house immediately. Just laying it on top of the ground is OK. If you want to make something more permanent later, OK See attached pic. Inside the crawl space there needs to be plastic on the ground, and any joints need to lap a min 12". Use 6 mil black poly, and since there is already somewhat of a moisture problem it wouldn't be a bad thing to run it up the walls 1/2 way or so. The plastic can be glued to the walls with certain types of construction mastic.
Pier and curtain foundation.... A little unusual around here, but OK - they work fine. BTW - what state and county do you live in?
>> This has been going on for who knows how long, and as a result the house tilts towards the back about 5 to 6 inches from the front door to the back door. <<
You are saying that the house is 5 or 6" out of level and that the foundation is than much out of level?
>> The house might only be 50 deep. << I assume the house is 50' front to back?
>> I also live next to a city drainage ditch/creek. Lined with rip rap, that has washed away over the years. It is normally about 10 inches deep by 8 feet wide. When it really rains, the water triples in width and gets about 12-15 feet deep--these are also guesses. The point is, it's impressive. The back corner of the yard is the worst, it's near a slight bend in the waterway, which leads to erosion. <<
If this is a "City drainage" can you get the city to come and fix or extend the rip rap? If it on some kind of right-of-way generally that means that you are limited as to what you can do there, but the insinuation is also that the city is responsible for maintaining it.
>> I'm also considering consulting outside sources locally so I don't overlook something obvious and cost myself more in the long run. <<
If you find a local grader he may come and look and give a few opinions for free. I wouldn't contact the city. They may come up with something like your runoff is adding sediment to natural waterways and force you to spend megabucks.
>> I did talk with someone who pointed out that my problem is mainly with surface water, and therefore a french trench might not be of great benefit. They suggested something akin to a dry creekbed as an alternative to give the water a path that would not further the erosion. << << That would be a swail that is done to direct water away from where you don't want it. They have to be not to steep along the length and width as as not to cause erosion though. See attached pic "swail" >>Would it be lined with something?
>> What would be a proper grade for such a slope? << Do you mean the proposed "dry creekbed"? 3 to 1 is about the steepest you can grow grass on and have it mowable, but you don't want something that steep if there are already erosion problems. >> I also have to factor in the chain link fence that is almost serving as a 10 inch retaining wall. << Sounds like that definitely needs to stay, even if it were buried more in which case you may likely need something on both sides of it. >> Just beyond the fence the level drops about that much before fore it begins a steep slope (greater than 1:1) down to the water. It might drop 15 to 20 feet over 10 to 20 feet width. << . Slopes that steep can only be stabilized via rip rap or retaining walls. Certain vegetation can be used for slope stabilization, but that is a pretty extreme slope. Also, again, we don't know what climate you live in and it depends on sun exposure, soil conditions, etc. See attached pic "foundation drain...".
A quick sketch might help too. Attached is one I did for another guy here who has drainage problems around his house. Your sketch could include some rough relative elevations in which case you would assign the number 0 to either the lowest or highest corner of the property.
If you're worried about the erosion and not compacting enough (the loader should be enough) can you tolerate building in terraces, temp or otherwise? I'm not talking terraces like in a garden but wide steps (10', 15', as wide as the yard will handle) in the soil that will slow the erosion.
Your French drain/foundation drain will have to daylight at some point, or slope into your rain buckets/drywell/whatever. I would assume that would be at some point in the existing slope if not below. I put that in first so that you don't have to dig through the new dirt to put it in later, if it would be mid slope you can fill around your drain with the new material and not have to install the end at all.
As far as the cistern idea I like gravity. It is simple and won't fail. If you use a pump make sure you have a gravity overflow and can't back up water into your drain if the pump fails, or can't keep up with the drainage. For the material for it I would check with (I think they all will turn up with a web search): Contech or Atlantis off the top of my head, but they might only do bigger stuff than you are interested in.