Question

Diagram   QUESTION: Greetings from a fellow "expert". I have a situation which I think calls for a French drain, but I want to double check that my plan is, to some degree at least, reasonable. I'm fairly handy, and from all the research I've done I'm confident I can do it.

I've attached a crude drawing to refer to because using only words could get...tedious. The basic problem is that right outside our front door is a hill leading up to the street. The hill is about 2.5 car lengths long. When it rains, water pools in the blue area of the pic to a depth of several inches (it has never lapped over the top of the sidewalk, however). And the area with the bushes gets slightly swampy (but not totally underwater, I think).

We have had zero water problems, primarily I think because the 2 front rooms are on a slab. FWIW, the house is > 30 years old.

My plan was to put in an FD where the red line is, hooking it up to standard drain tile (the green) once it's clear of the house.

I was going to make the FD trench 6" wide, and start at a 2-foot depth near the driveway with at least a 1-degree slope.

I think that's enough detail, but if you need more please let me know.

Thanks!
-Dave

ANSWER: Looks very good. You might want to be sure the FD is 12x12 wrapped in filter fabric with a perforated pipe in the center.

---------- FOLLOW-UP ----------

QUESTION: Thanks! (I think... because now I have to actually get to work :-> ).

3 Followups, if I might be so bold:

1. You said: "FD is 12x12 wrapped in filter fabric with a perforated pipe in the center". So you're recommending 12" wide, instead of 6"? Also, the summation of my research + advice from others is to not use regular corrugated drain tile, but rather to use 4 inch rigid PVC drain pipe (with 2 rows of holes in an "inverted V" configuration) to reduce the amount of dirt which gets into the pipe. Also, to put a "sock" (can't recall the proper name) around that pipe to further reduce dirt. Also, rigid PVC will be easier to clean out. Does that sound right to you, or is that overkill?

2. Can FDs be "T-ed"? It occurred to me that I could use a short FD section at right angles (in the diagram, it's the blue area between the right bush and the sidewalk), but I'm afraid that might complicate matters somewhat.

3. I said "2-foot depth", but that wasn't clear if I meant the total depth of the trench or to the top of the pipe or just where. So what I'm thinking of, from bottom to top, is:
* landscape fabric
* 4" pipe (sock-covered, PVC or corrugated, as described above)
* 6" of gravel
* 3" of soil, seeded with grass.
* landscape fabric (same piece, just "wrapped" around the gravel and pipe)

That's only a little more than a foot deep at the high end.

Will that work? I'm thinking "yes", since you described a 12" inch deep trench above. I'm getting conflicting information as to whether or not there should be gravel UNDER the pipe, or if it should rest directly on the landscape fabric. DIYNet says directly on the fabric.

Thanks once again for your assistance!

Answer
1. Yes 12x12. Yes rigid is better. Yes sock is better.
2. Yes you can and yes it will complicate grading. You need 1-2% slope on all pipe.
3. From top: grass, 3" soil, filter fabrick, 4" min gravel, 4" pvc pipe, filter fabrick, original soil. Dig 12" trench or greater to acount for required slopes. Lay in fabrick with excess folded out on each side. Place pipe, cover with gravel, fold fabrick over, cover with light soil and grass.
Sorry, did not get notified on your follow up and just happened to log on for another question.
Best of luck.