Culvert

[Jim Timber]

Home Depot was to the store delivery up at my property, but the Menards 4 miles away has all kinds of culvert options in stock, so that's what I went with.

Any decent building supply store will be able to get you 12" culvert in double wall. They might not have one on hand, but they'll be able to order it.

 

[Coyote machine]

Seek out where your town buys culverts when they need them. Depending, you might be able to buy from them on a stock delivery to the town garage.

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I wouldn't use anything smaller than 15" diameter. When you go 1/2 increase in diameter you increase volume by nearly 5 times. So a 12" to 18" would handle 5 times the amount of water. Your 12 was obviously undersized, and jammed because of that. Design for worse case, highest water situation, then you're covered and don't have to worry, or tear it up again down the road.

Search google for double walled HDPE culvert.
Link:https://www.google.com/webhp?source...2&ie=UTF-8#q=double wall hdpe corrugated pipe

 

[LD1]

IMO, too many people saying to go too big.

Let the terrain dictate height.

The culvert as a whole cannot be dug deeper than the outlet. So the "bottom" is gonna be fixed in the same location weather you use a 4" or a 36" culvert. So let the height be the deciding factor. A 18" culvert with 9" of dirt on top is 27" from the fixed "bottom" point. If that is significantly higher than the rest of the driveway, its gonna leave a hump, create a speed bump, and just look like crap IMO.

So look at the rest of the drive and determin the maximum height that would be acceptable. Size accordingly assuming 50% fill on top. Then if you need more flow, add a second or third culvert.

Oh, and adding 50% to the diameter( in the example above going from 12 to 18) only adds about double the capacity. (2.25 times to be exact). Not 5x's. Doubling diameter gets you 4x's the volume.

Of course all this assuming that the culvert getting crushed was the issue to begin with. Maybe I missed it but didn't see plugging as the primary issue

 

[Richard]

I found a brand on internet....sent local rep a question as to where to buy. Turns out my local co-op carries it! He went on to say that the county requires a 15"pipe, not 12". (he lives in same county)

So it's looking like we might have a 15". I'm calling the co-op on Monday. Nice thing is, the co-op is actually closer to me than the "local" HD or other large store!

 

[Jim Timber]

Perfect!

 

[Coyote machine]

I found a brand on internet....sent local rep a question as to where to buy. Turns out my local co-op carries it! He went on to say that the county requires a 15"pipe, not 12". (he lives in same county)

So it's looking like we might have a 15". I'm calling the co-op on Monday. Nice thing is, the co-op is actually closer to me than the "local" HD or other large store!

Well, there you go; and 15" is pretty standard for residential driveways. I did the dia./volume capacity from memory- sorry - guess I make mistakes.:confused3:
You did say the culvert was plugged with silt, no?

 

[PhysAssist]

IMO, too many people saying to go too big.

Let the terrain dictate height.

The culvert as a whole cannot be dug deeper than the outlet. So the "bottom" is gonna be fixed in the same location weather you use a 4" or a 36" culvert. So let the height be the deciding factor. A 18" culvert with 9" of dirt on top is 27" from the fixed "bottom" point. If that is significantly higher than the rest of the driveway, its gonna leave a hump, create a speed bump, and just look like crap IMO.

So look at the rest of the drive and determin the maximum height that would be acceptable. Size accordingly assuming 50% fill on top. Then if you need more flow, add a second or third culvert.

Oh, and adding 50% to the diameter( in the example above going from 12 to 18) only adds about double the capacity. (2.25 times to be exact). Not 5x's. Doubling diameter gets you 4x's the volume.

Of course all this assuming that the culvert getting crushed was the issue to begin with. Maybe I missed it but didn't see plugging as the primary issue

As usual, LD-1 is on point.

From my point of view, however, I would mention that resistance to flow is squared by each 50% reduction in diameter with the reverse also being true (but of course, my ability to relate to it comes from understanding airway resistance, as in with asthma and COPD.)

Thomas

 

[redman135]

One thing that nobody has said, make sure the water has a clear exit(20'-40'). This is to keep the water speed up to prevent silting up of the culvert. Many culvert failures are due to a blocked exit causing silt to be dropped in the pipe until it is completely blocked.

 

[Coyote machine]

One thing that nobody has said, make sure the water has a clear exit(20'-40'). This is to keep the water speed up to prevent silting up of the culvert. Many culvert failures are due to a blocked exit causing silt to be dropped in the pipe until it is completely blocked.

That's more of a factor in single wall culverts that aren't smooth interior. Double wall with smooth interior pretty much keeps anything from clogging the culvert, possible exception is ice.

 

[Streetcar]

That's more of a factor in single wall culverts that aren't smooth interior. Double wall with smooth interior pretty much keeps anything from clogging the culvert, possible exception is ice.

Red man is correct make sure outlet is clear. No matter how smooth the pipe ,sediment will build up just upstream from obstruction in the channel.