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Burying downspouts- Northern climes......

Discussion in 'General' started by DrA5, Jun 22, 2022.

  1. DrA5

    DrA5 The OTHER Great Dane

    I am looking at finally burying the downspouts at my house. I have been told to go 4" PVC hard pipe. The problem is, with the terrain on the north end of my house, I would need to then dig down pretty far to get a constant sloping, un-undulating line from the house to the terminus. Plus, that would be tons more $$ compared to a roll of the drainage tile/pipe.

    Those who have done this, is flexible drain tile ok? I was told to wrap flexible tile with weed/landscape matting so the soil doesn't get into the perforations of the tile and block up the pipe. How deep would you dig to lay the drain pipe in an area that freezes hard in winter? I am going the easy route and rent both a sodcutter and a trencher, as I don't want to deal with seeding and watering again, and as the glaciers stopped right in my backyard, there are tons of rock here that I don't want to use a shovel vs trencher.

    Any tips or advice before I tackle this is highly appreciated.
  2. Sprinky

    Sprinky Well-Known Member

    We have a minimum bury of 5’ for water mains here (Madison). We try and go 6’ bury minimum. Winter melt off of roofs is going to be your biggest pain.

    My advice is spend the extra and go 4” pvc. If you have to rod it out later you’ll be a lot happier. Any humps and valleys in your pipe lay will be collection points for leaves, etc. make sure you lay as straight as possible.
    DrA5 and ducnut like this.
  3. R Acree

    R Acree Banned

    I don't have personal experience this century with the deep freeze you guys experience. However, I have read that freeze thaw cycles can push rocks to the surface. Even if you carefully set the slope underground, expansive soils could conceivably change your slope and result in an ice plug below grade. If the DS couldn't flow, what is the chance of damage to your eave or roof?
  4. pickled egg

    pickled egg There is no “try”

    If you’re not going to heat tape the downspout, you’re better off converting between underground drain and above ground discharge with the seasonal changes.
  5. bergs

    bergs Well-Known Member

    In the event you want this to last and if you're not consistently running heavy equipment or passenger vehicles across any part of the run of the drain pipe, I'd use 4" S&D pipe and start at a minimum of 12" down.

    The minimum target I aim for is 1/4" drop per foot on the drain pipe.

    Dig the trench at least 12" wide, roughly set grade, lay in the landscape fabric, minimum 4" bed of 3/4" angular crushed stone compacted/ tamped, install pipe, backfill (min of 4" coverage on top and sides of pipe) with 3/4" crushed stone compacted/ tamped, wrap the fabric over the top of the trench to cover/ close off the crushed stone, backfill with excavated material leaving room for a min of 4" of loam.

    The crushed stone adds a "cushion" during winter freezes that inevitably moves the fieldstone around. It will also serve as reinforcement if you ever need to drive across it.

    For the fabric, find the stuff that looks like thick felt. Don't use the thin garbage that HD or Lowe's stocks. Get the good stuff from a landscape supplier.

    I'll guess that the person who recommended using "hard 4" pvc" is likely going to be schedule 40 or 60 drain pipe.

    Very generally speaking, the grade of the trench doesn't have to be dead nuts however the amount of deviation would depend on the total run from the first section of horizontal pipe.

    As far as the black, flexible corrugated drain pipe, I'd avoid it completely. I've excavated plenty of that shit and it's always clogged or collapsed.
    Last edited: Jun 22, 2022
  6. auminer

    auminer Renaissance Redneck

    Move south.
    TurboBlew, GM GIXXER and Sabre699 like this.
  7. YamRZ350

    YamRZ350 Nicorette Dependent

    I used sch 40 when I did mine. Went down about 30 in deep, no issues in the past 5 years. It's been plenty cold up here.
    DrA5 likes this.
  8. ducnut

    ducnut Well-Known Member

    Do it right—do it once.

    Corrugated drain pipe will clog, because of the internal corrugating capturing debris. It will clog, because of undulations slowing flow. It will be penetrated by roots, which will cause it to clog. It will break down over time, allowing it to collapse, which will cause it to clog. You will be digging it back up, because it’s clogged. Even if you needed to relieve the backside of a wall, there’s perforated 3034 (rigid, green-colored, drain pipe) for that, as opposed to shitty, corrugated drain pipe. Don’t be tempted by cheap and easy.

    Use rigid PVC, of some sort. It’s generally not permeable by roots at your needed depth and the interior is slick so clogs don’t develop. There’s DWV SCH40 (red printing), which is the strongest and most expensive. It’s pressure-rated and what you most commonly see at box and hardware stores. There’s foam core SCH40, which is still strong enough for this application and cheaper. It’s not rated for pressure and is commonly used for sewer lines where code doesn’t require DWV. There’s 3034 sewer pipe, which is the green stuff you occasionally see. It’s very thin wall and where you terminate it, a string trimmer will chip it off. I wouldn’t go this route, just for that weakness. You’ll most likely need to go to a commercial plumbing distributor, like Ferguson Enterprises, to find foam core SCH40. They have all the options in 20’ sticks. If you need a whole mess of stuff, just have them deliver it.

    Wherever you terminate these extensions, you’re going to encounter erosion, because you’re concentrating all your runoff to a single spot coming out of the pipe. You’re going to need to figure out some type of mitigation. If you choose stone, be sure and dig a basin and line it with landscape fabric, before laying in stone. The fabric will keep your stone from disappearing into the earth and this basin will slow and disperse your water flow. If you’re dumping into a creek, you’ll want the pipe to exit over water, so you’re not eroding a trench in/to the shoreline.

    You’ll want to do stacks at every downspout. Make sure they’re at least 24” above the elbow. Use the correct downspout adapters to fit PVC, as this will make for a cleaner look and tighter junction. The purpose of a stack is to give any water that might backup a place to stand, without leaking from the pipe. In heavy rains and minimal stack, the water will push out of the gutter-to-PVC junction. Obviously, you don’t want that.

    As for depth, in central IL, I’ve been as shallow as 12” and never had issues. If water is flowing, it’s above freezing, so you shouldn’t see issues.

    Again, do it right—do it once.
  9. In Your Corner

    In Your Corner Dungeonesque Crab AI Version

    Is it currently causing problems? If not, I'd leave it alone.
    BigBird likes this.
  10. bergs

    bergs Well-Known Member

    Regarding the suggestion of sending runoff straight into any body of water, look into your respective state's environmental policies for runoff mitigation before breaking ground.

    While I don't know how the state of Wisconsin feels about it, I can say for certain the states in the Northeast aren't too keen on it.
  11. G 97

    G 97 Garth

    Meh, you should concentrate on keeping your bird feeders filled so Cardinals don’t get angry and wake me up with their incessant mad chirping. What is wrong with you? :crackup:
    DrA5 likes this.
  12. Norton 357

    Norton 357 Well-Known Member

    You can use 4"double walled corrugated pipe, it's smooth on the inside and holds up to traffic but still has a little flexibility. We never connect more than 2 downspouts to a single 4" so you may need a larger trunk line and 4" to the downspouts if you have multiples.

    I work for a landscape architect/ install company so we do this a lot but not in colder climates.

    As was said above, do not use the roll corrugated pipe. You will regret it. If you have rocky soil that trencher will beat your ass, be careful
    ducnut likes this.
  13. DrA5

    DrA5 The OTHER Great Dane

    Between the raccoons pulling down feeders, blue jays pushing out the cardinals and the aerial battle between hummingbirds, feeding birds has become too stressful.
  14. bullockcm

    bullockcm Well-Known Member

    Come on now, Top Gun has nothing on a good hummingbird dogfight.
  15. cyclox

    cyclox moving chicane specialist

    For folks like me who are clueless about this stuff, what's a stack?

    We're getting a patio put in and the path from the side door to the patio is going to run over where I believe our buried drainpipe is routed. It's the cursed corrugated stuff, so before the concrete goes in, we're going to want to replace the corrugated drainpipe with rigid PVC, so this is a timely thread.
    ducnut likes this.
  16. ducnut

    ducnut Well-Known Member

    I probably should’ve put “stack” in parentheses, as it’s just a layman term.

    It simply refers to a vertical section of pipe. A lot of installers will cut off whatever it is they’re using right at the surface. Then, when a heavy rain occurs, the water can’t evacuate the horizontal pipe fast enough (corrugated is especially prone to this) and water starts overflowing from the downspout junction, flooding that area.

    Where I currently live, the hacks installed corrugated drain pipe that barely breaks the surface. With every single rain, nearly every junction overflows, which leads to my courtyard flooding. It’s because corrugated doesn’t flow very well, the runs are very long, there’s too much square footage dumping into them, and definitely not enough drop. Everything done at the place is on the cheap, which is why there are so many problems.

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