Asked on Apr 23, 2012

Trenching for Downspouts

Woodbridge Environmental Tiptophouse.comScott WJoey C


Where I live we have a high water table and a significant problem with water absorption in the soil. Sump pumps are the norm and run every 90 seconds or so to keep water out of the basement - I have two with battery backup to prevent flooding in the event of a power outage.
I am considering installing underground drainage tube to take the downspout runoff and route it to a section of the lawn where it can drain away normally. I intended to use rigid PVC pipe but have heard that professional installers use the flexible pipe. My concern is that the flexible pipe is not smooth on the inside and had a potential for settling and creating low spots. I suspected that I could direct bury the rigid PVC but would have to encase the flexible in gravel. Anyone done this or had it done? Thoughts?
9 answers
  • KMS Woodworks
    on Apr 23, 2012

    I did one of these projects for a client last summer. Not due to any heavy water issue but more of a cosmetic issue. We routed a down spout across the bulk of the gravel and rock drive / area in front of the garage doors. We went out over 35 feet, and used 4" sch 40 PVC. A large trencher / "ditchwitch" was rented to dig the channel. Here in the rockies that was the biggest headache as our ground is full of large rocks / boulders

  • 360 Sod (Donna Dixson)
    on Apr 23, 2012

    Even if you use hard pipe you will need to get the fall right or it will pool and maybe even bust the pipe looking at how far north you are. And yes we line it with gravel. For us that 4" PVC is very expensive compared to the 4" corragated pipe

  • Nothing especially professional about the flex corrugated elephant snout drainage pipe except that it is cheaper. It can collapse much easier if there is ever any traffic over it. I prefer scedule Forty solid. sometimes thirty or twenty The flz is bottom of the list where I need to work around rock ledge, trees, etc. Your plan is good. Always better to have a daylight drain instead of sumps

  • 360 Sod (Donna Dixson)
    on Apr 24, 2012

    We have installed these in some new builds lately, don't know how this compares to your sump pump though....

  • KMS Woodworks
    on Apr 24, 2012

    The one we did was a "daylight" drain with about 1/2" per foot slope.

  • Scott the reason that landscapers use the flex black pipe is its faster to use. Quite often then not there are issues with digging the soil so the flex type of pipe will move up and down and around these bumps. I would not worry much if this happens as the water will find a way out if not through the end opening but perhaps through the slots cut into the pipe if you use that type. I would suggest you use the hard pipe for at least 10 if not 20 feet away from the house, then convert over to the black flex pipe with the slots. Put a sock over the pipe and place it in gravel bed before back filling. A fabric cloth put on top of the gravel is also suggested. This way water will drain into the soil long before it has to leave the end of the pipe. Many landscapers simple use a large pipe such as this with lots of holes and the pressure of the water allows the pipe to drain when the end of the pipe never even sees daylight.

  • Joey C
    on May 11, 2012

    i would use all flex pipe dig trench deep and put a little stone down then pipe then put more stone on top then little dirt

  • Scott W
    on May 18, 2012

    Thanks for all the replies. Flex pipe seems to make sense from a cost perspective as well as ease of installation. What about the stone? What size is recommended?

  • 1/2" crushed stone would be fine. Do not bother with the stuff in the bags, way to expensive. Go to any supply house that sells crushed stone for gardens. Do not use the river stone however, It will never pack and the ground around the pipe will remain soft. They can deliver for you in truck.

Your comment...