# Huge Ditch crossing ideas



## Brandon1980 (Feb 2, 2017)

Hey all,

I am trying to figure out the best way to put a driveway across an 8' deep ditch. The ditch is 8' deep, 15' across at the top, and 6' across at the bottom. The ditch is in between two hills and is at the end of a large watershed that funnels into a creek. The ditch is dry unless it rains and with heavy rains there can be a large volume of water flowing through it. The bottom of the ditch is bedrock and the sides are clay.

My idea is to put in some sort of a large culvert. I'm trying to find the best solution that won't break the bank. The issue I see with the culvert is placing it on top of bedrock. I'm not sure if I would need to pour a concrete lip or facing around the culvert or just backfill to keep it from washing out.

Thoughts?....Suggestions?....

Thanks,
Brandon


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## griz (Nov 26, 2009)

Better check with the AHJ before coming up with a plan of your own....


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## Fouthgeneration (Jan 7, 2014)

Monkey copy several similar culverts in the area that have survived 50-100 years of rainfall and flooding.

Most likely you'll need local and state permits, maybe even a federal approval.."large watershed..." definitely a civil engineer who is a also a 'PE'

Your post makes anything following "premeditated" and Knowingly..not that it matters anymore for federal regs....

A few hours in an university library with an engineering program should get you some info on sizing the culvert for the # of acres drained, ground cover, permability, and hard surface % Rock and pavement and roofs, 

Don't forget to build a hundred year flood notch in the road bed to allow the overflow to pass with flooding any local existing structures in the watershed.

The 'splash block' water decelerator feature needed to stop erosion post culvert might cost more then the culvert. Avoid sharply graded culverts that will make water jet discharges....

Don't reinvent the wheel, seek out county engineers, and various State DOT web sites and pubs regarding drainage culverts.

Anything that "alters" the flow of water on the down hill or up hill land owners is an actionable tort.

Building a culvert under a road to several different properties is a whole different legal fish....

Cheapest: metal galvanized corrugated tube or tubes surrounded with washed rock, installed with a weep tile to drain arteasian water sources under the roadbed. Next round con create pipe, then box culverts either with bank side aprons in and out.
The intake end sealed with impervious clay or Benonite


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## dayexco (Mar 4, 2006)

bridge


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## rblakes1 (Jan 8, 2015)

Just check with your local army surplus store for one of these  






Or






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## Randy Bush (Mar 7, 2011)

Have seen lot of rail flat car beds used for bridges around here.


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## dayexco (Mar 4, 2006)

my 3 axle low boy had a 22' bed. nothing but steel beams, apitone plank. rated for 35 ton.


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## Moxley-Kidwell (Jan 28, 2011)

Couple concrete end walls, few sticks 48" CMP pipe, backfill and get the hell out of dodge. Just don't get caught!!


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## hdavis (Feb 14, 2012)

There are potentially multiple AHJs on this one. Get with your local BI guys and see what they'll require for either a culvert or bridge. You may have to use an open bottom box culvert, which would be pricey. Corrugated plastic would be a more usual solution.

Only an engineer will be able to size this, and I've seen them sized way too small some times. A lot of "ditches" are formal or informal parts of storm water management systems. I've seen ones like what you're talking about that had a trickle most of the year, but during Spring run off with raining, it would be 6' deep. Putting even a 5' a culvert in would cause a real problem, and wouldn't last, but a bridge does just fine.


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## Peter_C (Nov 26, 2014)

From someone who has had a few bridges wash out, at a very high cost...build it bigger and stronger than you think. That little dry creek can turn into a raging river in certain circumstances. Have fun with the watershed department too. Fortunately for us, they want us to build bridges to protect the salmon. In fact driving across a creek bed is not allowed during salmon season.

(The dirt road thru the creek was built by Oregon Department of Forestry during a fire to get their heavy equipment around without damaging our bridge further, then we had to have our logger remove it before the rainy season.)

The water will just about hit the bottom of the bridge sometimes, and that is normally a dry creek bed.


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## Brandon1980 (Feb 2, 2017)

Thanks for all the great advice! I know I have a lot of planning ahead of me, but I'm just trying to get an idea of what kind of system I'm going to need so I can project cost.
I haven't ruled out a bridge and I have even considered the suggestions mentioned about using trailer beds. I think an open bottom box culvert would probably be the best, but would cost too much for the project.
The good thing is that the entire watershed is on the same tract of land so I won't have to worry about the project effecting someone else. If cost run too high I may have to consider moving the bridge or culvert further up in the watershed where the ditch fans out wider. That would be the eaisy way, but I like to do things the hard way.


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## hdavis (Feb 14, 2012)

Brandon1980 said:


> I know I have a lot of planning ahead of me, but I'm just trying to get an idea of what kind of system I'm going to need so I can project cost.


About the best you can do is a SWAG based on bank erosion. You'd have to use the cross section of the stream at it's flood height to figure out how much flow your system has to handle, then see what size culvert would be needed. An engineer would take a different approach, and would probably come up with needing to handle more flow than what you get from just looking at the indicated high flow points on the ditch banks.

You'll need to do some research to find how to calculate flow in a ditch from the water depth / cross section and how much flow a given size of culvert can handle. One possible problem is the slope of the installed culvert is a critical factor in getting good flow through it, and you're dealing with a rock bed....

The size of the needed culvert is a big price driver.


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## tgeb (Feb 9, 2006)

I would agree with the suggestion of a bridge of some sort. If you size the pipe too small you can end up with a whole lot of trouble down the road when you get a freak storm.
And if the Gov. people get involved....that's another issue all together.


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## MonsieurBon (Feb 4, 2016)

Does your area have an agricultural extension program through a university? Quite often such programs will have ready-made guides to projects like these and have people to talk to.

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## NJ Contractor (Nov 12, 2016)

I suggest you hire an engineer to design it for you according to local, state and federal guidelines.


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## dayexco (Mar 4, 2006)

I just don't like playing, messing with a waterway, ditch. Nature has its way of making it the proper size. 

Throwing pipe, box culverts in there to me just adds issues. 

IMO, building over the channel seems so much simpler.


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## rino1494 (Jan 31, 2006)

Corrugated steel box culvert.


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