Drainage Help Needed!

[VaTractorGirl]

This will be the second time I am attempting to fix this problem. The first pic shows the house site and grade so you kidnda get the idea. The problem is that to the right of the house there is a hill that goes steadily up and finally levels so that the house is basically sitting in a hole. The second pic shows the far right side of the house (if your looking at it) which is right outside our bedroom window and is also where the septic tanks and pump station is located and everything pumps up to the top of the slope/hill about 560ft away. Water comes down the hill in a hard rain and we orignially had a swale (quite large) to divert the water away from the tanks (didn't want to overload the pump by having to pump rain water and bog out the septic field) and also away from the house. I didn't like how the swale looked and have tried various things now to try and fix it. The latest has been that I took the box grader and set it at an extreme angle so I could dig a trench, which worked. I then laid the 4" black pipe connected all the downspouts on that side of the house to it and took it around the front of the house. Problem now is that even though I checked the fall for the pipe, that in a hard rain it can't get rid of the water fast enough. So any suggestions? My husband wants to rent a trencher for this weekend (now he gets involved) and bury the pipe deeper. While we are doing this I am also trying to lower the grade on the right side of the house, it is only about 6-8' until the sidings starts and it is too hard to weedeat and such. But the more I lower the grade the lower everything would need to be. I also still have not planted my grass seed because I ended up getting zoysia seed and the last date to plant in this area is around the beginning of July. So I guess I will be planting next spring! Sorry this is so long winded, I think I just spent way to much time trying different things on my own.

 

[VaTractorGirl]

I can only get the second pic to come up. It is saying the first is too big

 

[Knight9]

Tried to lighten the photo.

Kevin

 

[VaTractorGirl]

This pic is from the back of the house so it kinda shows the problem This pic is older, the black pipe seen has now been buried and everything is hooked up and goes around the front of the house

 

[Knight9]

2nd photo lightened.

Hope it's not just my machine that sees the originals too dark to see /forums/images/graemlins/blush.gif

Kevin

 

[MicroPilot]

No, it's not your machine, those pictures are dark.

 

[beenthere]

Thanks for 'brightening' those pics. They were black on my screen. (I think I have a monitor that is on the very edge of being tossed, as the 'bright' is as far as it will go, and most pics I bring up are on the dark side - except ones I download from my camera).

Can't tell from the description, but water will only run when there is enough slope and enough room to run. Frustrating to deal with and, as in my case, my house is about 2' lower in the ground than it should be. But that (house elevation) isn't something that seems to become evident until the final landscaping and big rainstorm. /forums/images/graemlins/crazy.gif

 

[MicroPilot]

So is the problem that the run-off from upslope gets in the septic tank and/or that the downspout drains can't handle the flow of the water?

Maybe look at the threads here dealing with installing French Drains . These should be able to be scaled to handle any amount of water. Another suggestion would be to seperate the downspout drains from the run-off diversion.

 

[VaTractorGirl]

Both things are the problem. Along with with house sitting too far in the ground, but unless I wanted to walk up a flight of stairs to get in the house from my garage that is how it had to be. I orignially was going to take all pipe and put it into one large french drain. By the way when I was reading other posts on this subject most are using perforated pipe, I am not I am using solid black flexible pipe. The problem with the french drain is that I would need a very big hole and the fact that at this end of the property the soil doesn't perk, so IMO if I installed a french drain that had that much water coming into it, it would never dissipate. And I would think just start bubbling out the top of the ground.

 

[MicroPilot]

Well, you have to have the drain go somewhere. It's just not a hole in the ground filled with gravel. You'd have to plan it out and slope the trench to someplace lower. Is there anywhere on your property thats lower than your house?

 

[Cliff_Johns]

</font><font color="blue" class="small">( Is there anywhere on your property thats lower than your house? )</font>

This is really the key question. If there's no where for the water to go (drain away rather than fill a hole), you have to pump it, or siphon it somewhere else.

Cliff

 

[VaTractorGirl]

Everything to the left of the house is lower, that is not the problem, I have hooked up now the downspouts on the side of the house and from the porch buried and hooked up to one single 4" solid pipe that goes way in front of the house and discharges (right now) beside the driveway. I have quite a bit of pipe extra and wasn't sure what I was going to end up doing so I have just left it to drain out. The rains have been so hard that the 4" pipe cannot handle the amount of water that is coming through (possibly because I don't have the correct fall?) My husband now wants to rent a trencher and dig everything deeper and continue it out to the ditch. I don't really have a problem with the water once it leaves the pipe, we don't really use the property on the left side of the driveway. I just don't know if this 4" pipe is big enough

 

[Currmudgeon]

</font><font color="blue" class="small">( The rains have been so hard that the 4" pipe cannot handle the amount of water that is coming through (possibly because I don't have the correct fall?) )</font>

If the pipe doesn't have sufficient slope, then its flow capacity will be decreased. You'll want to plan this out and determine where the drain will discharge, and then slope the pipe uniformly to that point. If you don't have enough grade to make the slope, you may be able to get by with a larger diameter pipe. Rent a surveyor's level or rotating laser level to determine your grades and get the slopes even.

If you have a low spot to grade to, you can probably dry up the house by grading swales to that spot. The swales should be away from the house with the ground sloping down to them, to get the water away from the house. I try to keep grades on dirt or grass to 2% minimum (1/4" / ft).

The theory is easy. Water flows downhill. In practice, finding an acceptable downhill that goes from here to there can be a real bear.

 

[ByronBob]

The swail is the only thing I can think of. You might try running more perforated pipe because you gain all the soil absorption footage you don't have with solid pipe. Gravity will do a good job keeping the water down and not bubble up.

See the problem in hard rains is that it can't soak into the ground fast enough so it runs to your house. Perforated pipe will give you more soaking of the soil ability while you run it to daylight. The trencher with perforated pipe along with gravel can be your best bet. Until grass is in the problem is you have nothing to stop the water flow. Good luck

 

[Darren]

If you build a swale built according to permaculture standards you have to be meticulous on the earthwork. Ideally the rim of the swale should be the same elevation everywhere. The reason for that is a swale on a hillside is supposed to be a flat flat surface that disperses the water. As water flows down the hillside. the swale not only intercepts the water but it acts to spread the water over the entire area of the swale. Some of that water because it's no longer flowing down a slope will sink into the soil. The rest will flow off the swale at points all around the rim which reduces the flow at any one point.

the other way to stop or slow the runoff isto plant the hillside with stuff other than grass. Grass is better at slowing runoff than bare soil, but shrubs and trees are better yet. If you could transplant a mature forest onto the slope, you might see little or no runoff depending on the season. If it's the winter with frozen ground and the air temps increase followed by a rain, you'll still get some sheet flow runoff .

I don't know how much land drains past your house but the National Resource Conservation Agency office, NRCS, located in or near your county seat will have a booklet on building ponds that makes it simple to figure out how much runoff a drainage system might have to accomodate. The Farm Service Agency should have the same booklet. Figure the runoff based on a 10 or 11" rain to size the pipe (solid .. no perfs) needed. that should cover you for a worse case situation.

Another possibility is reworking the hillsides so you have multiple swales. You might be able to avoid needing a drainage sytem completely but you're looking at a lot of earthwork that few understand how to do correctly.

 

[Junkman]

You have received some excellent advise so far. The basic problem should have been realized and addressed before the home was built. Now it is too late, but this comment is meant for others that will read this post in the future..
A few things to add would be that the black perforated or solid pipe that comes in rolls has ridges in it. These ridges work to slow the movement of water and create resistance to flow. I would always prefer to see the white PVC smooth pipe used for these drainage projects for this reason. Also landscape fabric should be used in all instances to minimize any infiltration of silt. Follow carefully all the information in the French drain thread. If you increase the size of a pipe by double.... 4" to 8"...... you will increase the capacity by 4 times. For this reason, when you want to move a lot of water in a hurry, you should install extra pipes. There is no rule that restricts the number of pipes that may be laid alongside of each other, however people in their conservative financial thinking, feel that one is usually sufficient. In some applications, it might call for the use of more than 2, 3, or even 4. The time it takes to install 1 pipe vs. 4 is a small factor. Once the trench is dug, the rest is a piece of cake. If I were involved in the resolution of this problem, I wouldn't use a trencher, but a backhoe to dig the trench. Lay in landscape fabric, put down a thin bottom layer of 3/4" stone and set the down hill slope at 1/8" per foot for long runs and 1/4" slope for shorter runs assuming that you have the proper elevation to get this degree of slope. Then backfill with 3/4" stone to about 2" - 3" from the top surface. Cover the top stone with landscape fabric again, so there is no infiltration of silt in the entire trench, and then put down loam for the last 2" - 3" of soil. This trench would be at least 2' wide and 2' or more deep. The water will flow through the stone and the pipe, so this should accommodate most torrential rains. Without knowing the area that is collecting the rain water and running down toward the house, I have no way to determine how many 4" plastic pipes that you will need to accomplish this. The more the better. Remember, that you only want to do this project once and a length of plastic pipe isn't that expensive in relationship to the cost of the project or the damage that can occur if your home is flooded. This project is going to be expensive, but just consider the additional expense if you have to do it over. Do it correctly the first time and you will never regret it. One final thought.... you can also put a French drain part way up on the hill to pick up some of the water as it comes down. Also consider setting up a terrace effect so the water is slowed as it come down. If you set up the terraces properly, each terrace will act as a water collector holding some of what comes down before it rolls over the edge onto the next terrace. Then you could put in a few French drains, one on each terrace and know that with a few terraces and French drains on each one, that very little watter will reach the house barring a massive hurricane downpour. Planning is the most important step and I wouldn't rush into this project until you have a complete plan of attack. If it is a financial burden to do everything at once, then the terrace method will be the least expensive way, putting in the French drains starting at the bottom and working up the terraces as you determine how many more you will need based on experiences with future rain fall.

 

[Poncho]

I agree with Junkman and others who have recommended the terracing. Even though I have soil which is a sandy loam... I still get extreme runoff off of my property onto the neighborhood road (also dirt) and 2 neighbors yards (their houses actuall sit about 25' below the grad of my property with about 400 feet seperating us. What I did was about 20' inside the fence line (we left this natural for privacy for all parties) I layed old railroad ties down a stretch of about 300' and then used my box blade to build berms or swales as the water is slowed down and allowed to soak in. There is now virtually little runoff from my property to theirs. Please make sure where you direct your runoff to will not infringe on other neighbors.... like the HGN show says... we all share the same backyard. Good luck and lets us know how things go.

 

[CTyler]

</font><font color="blue" class="small">( I have hooked up now the downspouts on the side of the house and from the porch buried and hooked up to one single 4" solid pipe that goes way in front of the house )</font>

If I am reading this correctly you hooked up multiple down spouts to one 4" pipe? This is ok for a nice rain but storms and torrencial rains would back it up in a hurry.

I have 6 down spouts off my house each going to 4" perf pipe aprox 50' long. The first 10' goes out away from the house. The rest goes into a 2' deep 2' wide trench with pea gravel topped with 8" of dirt and grass. We have had a lot of torrential rains and they handle it fine. My 50'x64' shop has 4 down spouts with the same 50' set up except for one that is about 80' that helps drain a very shallow slope. The 50 footers need to be a bit longer cause there is a small hole at the ends of the pipe.

For example our storm the other day dumped 2+ inches in less than 3 hours. This was one of the lighter storms, this year has just been nuts!!! /forums/images/graemlins/crazy.gif

Looking at the pic with the slope toward the house made me cringe. Theres a good amount of work to be done to get it to slope back farther away from the house. I think the easiest way, still a fair amount of work, is to terrace the slope as was suggested. Adding a french drain would help as well. However if you can get enough slope away from the house its probably not needed. The work wont be hard but may take some time to move all that dirt to obtain the proper slope.

 

[Junkman]

I had also thought of this before making my answer and forgot. Glad that you caught it. I went back to look at the pictures and realized that with that amount of dirt, that the job would best be done with a bulldozer and a transit to make sure that the terraces were set correctly. There is a lot of material there to be moved and I can see where it would take 2 or 3 days with an experience bulldozer operator to get the banks of terraces into proper prospective. What a bulldozer can do in one hour, will take 4 or 5 hours with a box blade and tractor. If the project it started and not finished in a timely manner, and you get a bad rain, you are headed into having one heck of a mud slide headed toward the house. I would want to get it terraced and grassed as quickly as possible. We are headed into the best grass growing season next month. Warm days and cool evenings. Some triple 10 or 15 fertilizer and some seed and water and you will have an instant lawn. You can plant grass on almost any soil if you feed it properly.

 

[Degree]

So your saying water from the top of the hill flows down and fills up your septic system?

Easy solution! Plant sod, sod and more sod. When it rains the sod will soak up the water and the grass will slow water movement and will catch the water. This is what we've always done.