French Drain Expansion

Our house it located near the bottom of a hill and our neighbors have told us there is an underground spring nearby as well. The water table near our house if very near the surface and just a little rain creates flooding around our house.

The back of the house has a French drain system that directs water from the back, around both sides, to a storm drain in the front. I’ve noticed a lot of water pooling in a couple of locations near the house, one of them being around the AC unit.

To try to move that water out, I’ve improved the existing drain by lowering the outlet end, which previously was routed up and over some buried telephone line. I also added 10 feet of EZ-Drain prefabricated french drain to catch a lot of runoff from our neighbor’s yard,

I also added another 6 feet of drain that curves around the AC on the uphill side using singlewall, perforated drain pipe with filter sock. I added a small retaining wall near the AC unit to hold back the dirt that was finding its way into the AC unit. Before I changed it, the hill sloped right down to the AC unit. I put all the dirt uphill from around the unit and was able to level that area and reshape it to direct the water away from the house toward the new 10’ EZ-drain extension. Any water that either rises with the water table or makes it past the retaining wall and EZ-drain should hopefully be caught by the new 6’ run around the AC unit. 🤞 I may also add a run from the downhill side of the AC unit along the old run to the storm drain, keeping two pipes in the trench to double the volume of that drain.

I used a Whye “Y” joint to tie into the existing drain. I also cleaned all of the old rock that covered the existing drain. Over the years a lot of erosion brought dirt into the system and reduced its effectiveness. There were also roots growing into the sock of the old system. I will likely need to dig up the entire run and clean it all out. It could have been installed with the original build, in ‘93!

Whoever put in the original French drains used catch basins at the origin end. I removed the catch basin on this side and replaced it with a 10’ extension that I capped at one end. This should reduce the amount of dirt and junk that finds its way into the drain. Because the drain is covered with rock, it’s considered an open drain and anywhere along the drain can catch runoff, so no need to have the catch basin.

I also made sure all of the runs I installed had a downhill grade to them.

I put the sock-covered drain directly on the dirt at the bottom of the ditch, then surrounded it with rock. The sock should keep dirt out of the perforated drain and the rock forces water into the drain by reducing the volume available to water in the ditch.

There were plenty of thick tree roots to remove. A sawzall made quick work of those.

The videos aren’t great quality. They are mostly for my use as notes. In the following video, you can see runoff from the neighbors yard being caught by a wattle and directed into the extension of the French drain:

And in this video you can see the improved French drain emptying into the storm drain. The improved drain is the one spewing brown, dirty water.

This was all learning for the larger project: installing a dry well and multiple runs of drain feeding into it, then tieing the well into another existing drain that leads to the storm drain. Once the drain system is done, install a fire pit in the area!