Tuesday, November 4, 2003

The French Drain, Part 1

December 2002 to December 2003 

When the house was built, there was no fence. When we put the fence in, it only went between us and our neighbors, so it was still open to the front of the house. To keep the dog in the back yard, we needed to close it off, so we contracted for a guy to put in the section of the fence with gates on both the left and right side of the house. 

Before I did that, I wanted to make sure that there was enough dirt to put the fence posts in. When I dug down on the left (the East side), I got dry sandy dirt. On the right (the West side), I got water. The whole West side of the house was saturated with water. This was causing problems with the foundation of the house -- the outermost layer of the foundation was spalling off. 

and after it rained, the whole lawn was standing water. 

The problem was that there had been a swale that drained this part of the yard onto the empty lot next store, and then back and down the hill. But the empty lot had been built on and the builder filled in the swale, blocking the water from our front lawn which flowed down the yard, around the house and then just stopped. 

The solution was to dig a French drain to take all this water back down the hill. I dug a trench, about a foot wide down 2 to 3 feet. We then filled this with gravel and a couple of 4 inch PVC drainage pipes. This allows the water to filter thru the gravel and down the trench, past the slight raise that was keeping it in place. 

At the front of the house, the downspout from the gutters for the front of the house was tied directly into one of the drainage pipes in the French drain.


In addition, the other two drainage pipes just ran straight out to the lowest spot in the front yard. 

The trench, gravel, and drain pipes ran back under the fence and then turned left to run along side the fence to the back of the left side of the house.

At the end of the fence, we turn and continued until the back yard fell off enough that the yard was lower than the end of the drain pipe, so any water coming down it would drain off down the hill. 

This process took a year or so to dig out. I needed to be careful around the trees. Plus, as with much of the yard, the dirt is not very deep before I hit rock. These rocks had to be dug out to get down as far as possible -- generally down to bedrock about two to three feet down. Whenever a rock was encountered, a decision had to be made if it could be pulled out completely, or if it was too big to handle, and would have to be broken into pieces and removed. There were two sections where the bedrock itself was not level, but bulged up to stop the flow of water. I used a jackhammer to break thru these bulges to get a clear path for water entering the trench at the front yard to flow by gravity to the end of the trench. 

The actual installation of the pipe and rock, which is surrounded by a weed barrier form of landscape cloth, to allow water to flow in, but keep the dirt and roots away from the drainage pipes, was done by Drainage Specialist, for $2000 ($500 down, $1500 on completion). 

 This solved the drainage problem. It left us with a hole in the backyard with the three drainage pipes sticking in them, but we had other problems that needed to be worked on, and we weren't sure how to finish it off, so we just left it for later.