Drainage Problem

[RF]

Hello forum,
This is officially my first post on this forum. Before I ask for any solutions to my problem, allow me to give some background info/history:

Problem 1:

- About 15 years ago, my house began sinking. It was eventually jacked up and raised. Unfortunately, my dad built a patio in the backyard before the house was raised. As the contractor raised the house, the patio stayed as is and eventually connected back to the rear of the house. Presently, when it rains here in southern Louisiana, the backyard tends to fill with a lot of water. What I am proposing to do is to establish a drainage system from the backyard to the front street. Here's my question: How do I determine the difference in height from the backyard to the front. What I would like to do is connect a catch basin from the patio gutters and connect it to PVC towards the front where it finally drains. The distance from where the catch basin would be in the back to the front would be about 100 feet. Normally, drainage occurs from back to front, but since the house was raised, not enough fill dirt was was placed back into the backyard. So now, rainwater tends to collect in the backyard.

Problem 2:
When the contractors jacked up the house, they tunneled their way through beneath the foundation. When work was finished, they did not fill underneath the house with soil. What they did instead was "skirt" around the foundation with a black tarp, connect the tarp to the foundation then filled in dirt around the house. So now, we have a 3 foot void beneath the house. As time went on, the black tarp eventually tore, allowing sourrounding fill to erode underneath the house. As this happened, guess where the rainwater eventually drained to? Yes, underneath the house. So when a heavy rain should occur, the void underneath the house will fill with water. Once filled, it will begin to flow back into the backyard. This is where I want to start a drainage system, but I believe the backyard may be about level with the front. What's everyone's best advice to determine the difference in height from back to front? I've tried using string and a line level, but I think the difference is too great to get an accurate level.

Any and all advice is much appreciated. Thank you.

Regards,

RFerrer

[mrcaptainbob]

Backing a void covered with a tarp? Those guys should be shot! Well, on to your question....checking the level front to back. Get a small diameter clear plastic tube that would span that distance plus another ten or so feet. Fill it with colored water. Raise the 'taller' end until the water level would be pouring out both ends at the same time. Once you get it to dribble from both ends at the same time, that is the level. Subtract the shorter distance of tube end to ground from the longer one, and that's the diff in height.
Trenching a couple/few feet around your house for a french drain would stop most surface and underground from going to the underside of the house. A sump pump might be needed to help. That water under there can't be healthy for wood rotting or mold creation or increasing a chance of foundation cave in. Using the PVC to drain the water away is a good plan. There is a thread relating to that issue on TBN. Some good suggestions there. Welcome to TBN, sorry it has to be under such a serious circumstance.

[RF]

Yeah, I guess my parents were misled, simply because the contractor did not want to fork up the money to fill underneath the house. I will try the water level method, though I'm not sure the french drain system will work here in southern louisiana. If I dig a foot down, I'm already hitting the water table. I'm just hoping I get a good grade from the back to the front. That way I'll install a catch basin for the gutters and let gravity lead the water via pvc pipe to a pop up drain near the curb of the street. If not, then a sump pump would have to be installed.

Thanks for the help!

Regards,

RFerrer

[mrcaptainbob]

Oh yeah, Louisiana. Had the good fortune to visit there many years ago. Digging down a foot and hitting water isn't good. You're right about that French drain not working in a situation like that. I was thinking of a way to upset any water tables from accessing the foundation. Too bad we can't just place a nice thick membrane all around the place....I knew some people who purcheased a house built on some old limestone pit. Over a period of time the house started 'settling'. They were having to step up to their driveway after a couple years. after taking the builder to court, they did manage to get most of their money back. The house was unsalvageable and is now probably past the eves!

[LazyPup]

RF,, I prefer to use a laser level to shoot grades.

Fortunately I happened upon a laser 2' level at my hardware store on the cheapie tool pile for $8 and it will shoot a line over 100 yrds in daylight.

I attach the laser to a photo tripod then i can measure grade at any convenient point along the laser reference line. I find it very helpful when running drain lines as 4 inch drain lines are required a 1/8"/ft pitch (one inch in 8 feeT)

[ksfrioux]

Greetings to one and all. This is my first posting on this list.

We have a 30 year old house that we brought about 8 years ago. The previous owner was a do-it-yourself kind of guy. Although we love many of the improvements he made, we are having difficulties with water drainage in our backyard. The previous owner added on a summer room. Any time there is any rain/snow water is not draining down the natural hill in our yard. Instead it is draining towards our house and coming up under the concrete slab into your summer room. We have had a couple of contractors come out and give suggestions. One contractor suggested digging up our concrete padio and putting a new one down. This option is a bit pricey and we are not sure if it will even work. I also had someone come out regarding mudjacking and raising the foundation up. This gentleman said that we did not need this and to try digging drainage ditches coming down from our downspouts and draining down the hill in our backyard. In particular the area right where the water is seeping in, he suggested digging a trench in the concrete and adding a drainage pipe there. Does this sound like a good idea? Any other suggestions? Thanks,

[kactuskid]

The last guy is on the right track. Though I'm not sure the ditch needs to be right through the concrete, it could be dug around the perimeter of the concrete and then drain tile installed to drain via gravity to the backyard. Drain tile could also be installed to pick up the downspouts and route this water also towards the backyard. Here's some links to explain subsurface drainage and how to go about installing it. I had this done in my backyard and it's worked great for the last 10 years.

http://grounds-mag.com/mag/grounds_maintenance_install_drainage/

http://www.houstonlandscape.com/Drainage.htm

http://www.ndspro.com/subsurface_drainage_install.html