I am in the process of redigging the trench to daylight the draintile around my house.
This is the third time I am digging this trench.
The first time the trench did not have enough fall, and over the course of a year the pipe settled and then wouldn’t drain at all.
The second trench was much longer and had plenty of fall. While the trench was open the water level in my sump crocks was 16 inches below the slab. However once I filled the trench with 57 stone wrapped in filter cloth after a day or so the water level in the sump crocks increased by 10 inches.
Now I am digging the trench wider and deeper still and I plan to put a corrugated pipe in a sock inside the stone inside the filter cloth.
Is this the most effective way of draining this water? The water table is very high in my area and I am preparing to finish my basement, so as much as I like playing with the backhoe I want this to be the last time I dig the trench.
In general what is the percentage of water flow possible through a trench filled with gravel compared to an open trench? I should note that the water still drains so that my sump pumps never have to run, its just that they had to fill such a great amount of the stone depth that the water level backed up under the house. The lack of buffer is just unacceptable in what is about to be a finished space.
Thanks
Jeff
Replies
If you are truly daylighting it shouldn't matter.
If you are truly going to daylight, then the permeability of the 57 agg, is pretty high, it moves at about 2-ft per minute with three feet of head.
I'm kind of confused about wrapping the gravel if you are truly going all the way to daylight and not building a french drain.
Wrapping the gravel would be done to prevent silt infiltration from the adjacent soil.
If you run your line to daylight make sure you put a screen over the end or you will have critters building a home.
Daylighting draintile
Thanks for the replies.
Will a large #2 stone drain better than 57s? I plan on using 2 or maybe 3 runs of 4" corrugated pipe in the bottom of the trench to relieve the water but I would like the stone backfill to be as permeable as possible. Maybe a riprap type of stone would be best?
Thanks,
Jeff
Generally the larger the better, up to the point where the rock will no longer keep the soil out (or punches holes in the fabric). 57 contains a lot of small aggregate and is not ideal.
But the pipe is what you really want.
>>>Now I am digging the
>>>Now I am digging the trench wider and deeper still and I plan to put a corrugated pipe in a sock inside the stone inside the filter cloth.
Around here people tend to avoid the corrugated black pipe in favor of perforated PVC. The PVC pipe is considerably more rigid, and doesn't have that nasty "pre-curled" tendancy. Hence, it tends to avoid the crests and troughs that the black stuff gets. It's also nicer to work with IMO, and only moderately more expensive.
We usually cover the drain rock with a layer of high quality filter cloth, essentially making a giant burrito of drain rock, with the pipe at the bottom of the burrito.