French Drain Project.

[DMF]

Nice project! I did the same thing last year at our house although the bank wasn't as steep. In my case I had originally pitched the grade so it came up from a swale at the bottom of the hill back to the house. Water in the basement wasn't an issue, but I couldn't get anything to grow/hold in that swale. In the spring it became a brook and eroded it into a trench.
Last year I rented a mini-excavator, trenched along my swale, tied the two downspouts at that end of the house and my water softner line in as well. I brought it a good 150'+ and dug a big drywell. I used landscape fabric in the trench (I thought it would help the stone stay free of silt) and I used 3/4 stone up to 3" - 4" to the original grade. Seeded it all and (knock on wood) it's been working great ever since!

[dholly]

Looks great, you're taking no chances with the scuppers! I just finished laying almost 200' of the same drain line and found getting a 100' fabric sock on a 100' pipe is a real PITA. It's like 'Chinese Fingers', the harder you pull the harder it stays put! Thankfully, the sock label included a very handy tip. It bears repeating for those who don't know... cut a 2-1/2' section of 6" pvc to feed the sock onto, then feed the 4" drain tile thru the sock loaded 6" tube, slipping the sock off as you slide the 6" tube down the drain line. Tada.

[Highbeam]

Our local home improvement stores, Home Depot, sell the perf pipe pre-socked. I need to do some underdrains/curtain drains/french drains/farm tiles whatever you want to call them. I am an engineer and have seen several ways to do it. It seems that rock and perf pipe without a filter is the traditional way to do it. We have had success in the city with a socked pipe and sand to the surface. It seems the sand is less likely to clog with sediment than the rock.

What is the general consensus about pipe, fabric, and backfill in clay type soils. The pipe will be 4 or 6 inch perf pipe.

[Donman]

In your second post I saw a red paint line in the dirt and guessed from another post it was for the gas line. I didn't see any sign of a gas line in the pic by the downspout. Gas lines in Michigan are only about 18 inches deep that close to the house. How deep was yours?

[Highbeam]

Here in WA, yellow is for gas and red would be phone or power. Good idea to get locates.

[dholly]

Highbeam - what I read is that soils with a higher clay content have a lower ability to move water both horizontally and laterally; therefore, they require tile to be placed shallower and closer together for rapid drainage. Sandier soils can be drained with deeper widely-spaced tile, but tend to need sock or sleeve filters to prevent smaller soil particles that lack cohesiveness from entering the tile.

In clay soil, the U.S. Golf Association recommends 4" corrugated, perforated drain pipe installed at a depth of 2 to 3' with lines spaced from 10' apart when 2' deep to 20' apart when 3' deep and. Backfill the trench with 6 to 12" minimum of #57 washed gravel (1/2-3/4" in size average). For maximum effectiveness, the trench should be backfilled leaving no more than 1' to the ground surface. Use topsoil (not clay) to fill up to the surface layer and use a pipe sleeve regardless of soil type or if in rock or not.

You are lucky, my HD does not offer pipe with preinstalled sleeve. [img]/forums/images/graemlins/tongue.gif[/img]

[Highbeam]

Does width of trench really matter? I ask because rather than dig a big trench with a hoe I can use a chainsaw type trencher and run the pipe quickly and cheaply. Less gravel too. Would want a wide enough trench to work in though.

My boss engineer actually recommends sand as backfill since the surrounding soil is less likely to migrate into the gravel voids and plug it. The sand could be run clear to the surface to pickup surface water more effectively.

Socked pipe seems to be ideal but I'm sure the cost is higher than socking your own.

[dholly]

</font><font color="blue" class="small">( Does width of trench really matter?)</font>

Yes, see Chapter 6 of The Complete Corrugated Polyethylene Pipe Design Manual and Installation Guide at www.plasticpipe.org.

[Highbeam]

I don't think that applies to what I meant. Does the width of the trench matter in terms of the pipes ability to dewater the site? Constructability and proper bedding of the pipe being a seperate issue. The reference gave me a 22 inch trench for 6 inch pipe.

[dholly]

The trench width should be no wider than what is represented in the attached table, except as necessary to construct the trench or install the pipe. According to ASTM D 2321, the trench width should be no wider than what is required to safely and conveniently compact backfill material on either side of the pipe. As I understand it, in clay soils you do not want to make wider trenches, rather, you will need additional drain line laterals. More info HERE.