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Rain garden next to driveway

Discussion in 'Landscape Architecture and Design' started by Velo781, Nov 1, 2019.

  1. Velo781

    Velo781 LawnSite Member
    Messages: 86

    I've been wanting to dig out a rain garden in our lawn next to our concrete driveway. Currently the earth is a couple inches above the driveway, so in heavy rains the whole area floods and leaves a bunch of dirt in the driveway.
    My question is if it may not be a good idea to have water collect directly next to the driveway. Will the draining water erode under the driveway? I'll attach a pic of the area.
    I don't want to create a problem over time that will undermine the driveway. Thanks.

  2. ed2hess

    ed2hess LawnSite Fanatic
    Messages: 16,097

    Rain garden:dizzy: Take picture
  3. OP

    Velo781 LawnSite Member
    Messages: 86

    Basically just a depression in the surface (bowl) with some appropriate plants and mulch maybe. Our city utility gives some rebates if you jump through all their hoops of an 'approved' rain garden. That's not why I'm doing it though.
  4. TPendagast

    TPendagast LawnSite Fanatic
    Messages: 16,565

    Rain gardens shouldn’t have mulch in them
    Don’t create a depression next to your driveway like a swimming pool (straight down)
    You’d need a shoulder (slope) to the bottom

    a few feet off and sloped should cause any havoc

    I’m not a big fan of rain gardens
    Make sure you’re building it to spec for what the city wants.
    There’s little difference between a retention pond/cesspool and a rain garden If you don’t make it right
    Velo781 likes this.
  5. AGLA

    AGLA LawnSite Bronze Member
    Messages: 1,825

    A rain garden is only good if your soil percolates so that the water infiltrates into the ground. If you have a lot of clay in the soil, you'll only be making a bigger puddle.

    Take a picture from farther away so that it tells more of the story.
  6. TPendagast

    TPendagast LawnSite Fanatic
    Messages: 16,565

    If you make the rain garden to spec
    Then it doesn’t matter what the indigenous soil is
    That’s the point of “making” a rain garden:
    You dig a hole and install a rain garden, including sands, soils, rocks, plants etc
  7. phasthound

    phasthound LawnSite Fanatic
    Messages: 5,873

    hort101 likes this.
  8. AGLA

    AGLA LawnSite Bronze Member
    Messages: 1,825

    A proper spec' has to consider the existing soil below. If you use a generic spec' and you have clay immediately below it will be a bath tub with nicely spec'd sand and soil media bathing in it.

    The point of a rain garden is to treat runoff first by keeping it out of surface water bodies (ponds, rivers, lakes, …) and then
    by having plants use the excess nutrients captured in the soil
    during the infiltration process before those excess nutrients get down into the groundwater and migrate to other surface water bodies or wells.

    If the runoff does not infiltrate into the soil it is just a skanky puddle / mosquito farm and once it is full the runoff continues past it on the surface bypassing the rain garden.
    Idlewild, rlitman and hort101 like this.
  9. TPendagast

    TPendagast LawnSite Fanatic
    Messages: 16,565

    I have installed 3/4 of the rain gardens in this state and the three largest ones.
    I’m well versed on them and how most designs don’t work.
    They drain off into storm water sewers more often than not
    It’s main purpose is to filtrate pollutants (than are collected by rain off hard surfaces like roof tops and asphalt) and to slow storm water erosion.
    SOME rain gardens can work in a flood puddle way (fill up then percolate) but most are designed with overflow run off into storm water system.

    most I have seen are just designed like crap (unless they let me alter them to work right)
    And DO become mosquito farms.
    thats mainly why I don’t like them very much.

    each one really needs to be specd for the area it’s in.
    But I suspect designers grab a copy paste and throw it into a details page, which is why most ultimately don’t work

    then you end up will ALL the wrong plants (I was forced to install one with red twig dogwood)
    Was nearly impossible to keep the red twig watered because it’s designed to drain not hold water and dogwood isn’t draught tolerant.

    that was a fight we’ve had running since early 2017 - that literally just ended last week, with a “we promise not to do it that way next time”
    I kinda hope they won’t do another raingarden - tbh.
    There’s other ways to manage storm water run off.
  10. AGLA

    AGLA LawnSite Bronze Member
    Messages: 1,825

    I agree with just about everything that you just wrote. The only thing that could be more clear is that the overflow is not really part of the rain garden. It is to bypass the rain garden when there is more water than the rain garden can handle. I definitely agree that every rain garden should have an overflow even if it is just a swale to continue to flow somewhere else.

    Let's face it, these are mostly inadequate because they are undersized simply because the amount of space necessary is too costly (whether in dollars or room on the site) to be practical. They are almost always done because someone is forced into it by regulation. The rest of the time they are being done so that someone can tell everyone else what a great eco-warrior they are.

    I appreciate that you do your best to do them right.
    hort101 likes this.

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