Water discharge from French Drain

[kbmcdowell]

I just installed 100-ft french drain in a swale on my land. I also tied in the downspouts from the house, and the sump pump discharge. The land for the most part is clay and rocks, with some left over topsoil sprnkiled on top from a very poor final grade in 1998.

I used 4-inch perforated rigid pipe, #1 crushed stone, landscape fabric around the pipe, plenty of grade (about 1 inch per 40-ft). I ran the solid pipe out to the road, and cut the pipe at an angle and put down some stone, the water drains into the town’s concrete drainage around our cul-de-sac.

We just had our first rainfall with the system in place, and tt works like a charm, and I am getting a ton of water through it.

Question # 1: Should the water be a light brown color? How muddy should it be, and will this last a long time? I am assuming there is suspended sediment in the water, and am expecting the neighbors to put up a complaint if I run a lot of sediment into the gutter.

Question # 2: I have had a couple of landscape people with conflicting opinions on this one. I wanted to lay straw over the french drain prior to placing about 6-8 inches of screened topsoil on top, then plant grass, creating in affect a less severe swale over the franch drain. One guy says no problem on that plan. The other guy says that the topsoil will reduce the effectiveness of the franch drain, and that I should spread decorative stone on top of the drain, and live with that, no topsoil. Which finish method is more commonly in use? Will I kill my french drain if I cover it with straw and topsoil?

Kip

[Unregistered-HarryC]

After the first rain or two, the gravel and pipes etc should be washed off, and the water should run clear, with little noticeable color. The color is obviously soil, and if it keeps up its because theres an erosion problem somewhere in your system.

How you cover the system depends on what it needs to do. Topsoiling over it will prevent surface water from getting into the pipe, but will allow groundwater into the pipe. Fully backfilling with gravel will allow surface and groundwater into the pipe.

A swale is open ended, and therefore doesn’t impound water. A depression is closed, and will impound water. Since you mentioned you have a swale, you probably dont need to collect surface water, therefore topsoilling over it will be okay.

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