What are my downspout discharge options?


Old 10-01-18, 02:42 PM
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What are my downspout discharge options?

I had a new garage built and am looking at rain mitigation options. The garage is built on elevated terrain such that water runs away from the structure. I live in a northern climate so snow and ice would be a consideration.

I'm looking at three options:

1. Simple discharge chutes that sends the water down the sloped driveway.
  • Easiest to do
  • Easiest to unclog
  • Lowest cost
  • Concerned about creating a very icy driveway on days where it rains and freezes
2. Running a pipe out to daylight under the driveway and letting it discharge out the side of a hill.
  • Second easiest to do (just need to dig a trench and make sure it's sloped)
  • Can service two gutters at once
  • Easy to unclog with very long pipe arbor if needed
  • Concerned about potentially heaving/sagging driveway overtime, creating a crack or split
  • Concerned about an ice dam forming at the end, and damaging pipe by chipping away at the ice over time
3. Burying some dry wells to capture and store the water, and let it percolate down into the soil.
  • Most effort
  • Highest cost
  • Water table and soil infiltration tests allow for this
  • Does not interfere with driveway in any way
  • Potentially very difficult to unclog, even with a catch basin / cleanout port
Here are rough top-down views of what the layout would look like:


The rear discharge I'm not as concerned about as the front. I can sort of do whatever works back there. The front discharge though, is more complex.

Just wondering what people might recommend.
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Old 10-01-18, 03:25 PM
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I don't like the idea of tunneling under the driveway. Although there are a variety of methods, it is difficult to re-compact the dirt around the drain pipe and in turn and over time the driveway is very likely to sag and crack.

Dry wells should not be installed near the foundation. Doing that is likely to lead to basement flooding.
Old 10-01-18, 03:47 PM
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Why not just let the water run out on to the grass?
Old 10-01-18, 04:43 PM
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Option 3 if there is slope that the pipe can go to the left for the 2 downspouts and out the front with another pipe.

Under the drive would be ok if you got it in before the drive was installed, very difficult to make a small hole and impossible to back fill.

I agree, I always have all my down spouts in pipes draining away from the structure!
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