Questions on installing a culvert on my land

[chesterspal]

I have a mountain runoff "gully" that divides most of my property from where I drive in.

I need to be able to access the other side with my small (6000lb) pickup truck. Building a bridge to do this will be costly and, I feel, unwarranted since only I will be using it.

Installing a plastic culvert makes the most sense. I have the booklet from FEMA called Provate Water Crossings. They seem to frown on using culverts in favor of building bridges. If a culvert is built, they discourage using more than one pipe.

This is a sample if what I see around my area.



Where I live I see double culvert pipes all over the place. Just two, say, 15" pipes side by side under a driveway. No special entrance or exit features. They appear to work just fine and allow for dealing with shallow, but perhaps, wider runoff gulleys.

So, to get started, if I have a gulley that's 30" deep with the bed around 30 to 40" wide...



With around 4" of running water after a decent rain or snow melt



Is it feasable to use two 15 or 18" diameter plastic culvert pipes side by side so as to still
have (the required minimum of) 12" of compacted fill on top?

Appreciate the help and advice on this.

[clearcut]

Where you are located can make a difference. 

In many places a permit may be required. Check before you dig. 

The resource I recommend for landowners working on their roads is Handbook for Forest, Ranch, and Rural Roads: A Guide for Planning, Designing, Constructing, Reconstructing, Upgrading, Maintaining and Closing Wildland Roads. Free PDF. 

[chesterspal]

The head zoning official told me a permit is not required. I can go ahead and install the culvert.

Thanks for the booklet.  

[doc henderson]

go for it.  the entrance and exit matter more if the water runs fast, like in the mountains of Colorado.  It can start to undermine your culvert.  We hooked numerous bits of culvert together to make bends ext.  the road would otherwise get eroded to the extent that one corner required a 3-point turn of sorts to not fall into a 3-foot-deep bully. At our scout camp in Colorado.  Fun in a Fullsize crew cab one ton dually with a 14-foot trailer in tow.



 

no water now but always wet or muddy.  when it rains there will be a foot of water coming to this lower spot.  We made the bridge 36 feet, from the prev. 20 feet.  You can see the ends of where the old bridge was under the new one.  this new bridge is 6 feet wide to accommodate 4 wheelers.  It had approaches built on each end.  prev.  you had to go downhill to the bridge, and back up on the other side.  now just a slight gradual grade going up walking Right to Left side of the bridge.  Without the bridge, it added a half mile to archery and rifle areas at camp Alexander.

[Ljohnsaw]

Do you have a sawmill? Is there one near you? Looking at how small a span, I'd be tempted to have some massive beams span the gap and be done with it. Something like 8x12, and run some 3/4 all thread to snug them up.

[Wlmedley]

Small pipes tend to stop up easily with leaves and other debris.I have a small stream about the same size as yours and installed a 36" plastic culvert.Most of the time it's overkill but probably twice a year we'll have a gully washer and anything smaller wouldn't handle the flow especially with leaves and small limbs ect washing down the creek.Also recommend getting pipe with smooth liner inside.

[Magicman]

My vote is for two "used" utility poles across and deck with 2" White Oak.  Bridges don't cause problems whereas culverts overflow, clog up, & wash out.

Your pictures show a perfect example for a 10' or 12' bridge.

[chesterspal]

Small pipes tend to stop up easily with leaves and other debris.I have a small stream about the same size as yours and installed a 36" plastic culvert.Most of the time it's overkill but probably twice a year we'll have a gully washer and anything smaller wouldn't handle the flow especially with leaves and small limbs ect washing down the creek.Also recommend getting pipe with smooth liner inside.

The problem, as I see it, is I have only around 30" of depth to work with. Digging down and removing the rocks in there will add a few inches... but I will not have enough depth to bury and compact a 36" pipe to at least 50% it's diameter per best practices. A pipe, not properly compacted, will fail the first time I drive my 2004 Ford Ranger over it  :'(.

Hence, my reason for looking at using two smaller diameter pipes, side by side, as in my firsts image, to cover much of the bed width.

True, I will need to stay on top of it and clean out the inlet from time to time. However, that issue now exists even without the culverint being there. All kinds of crap land in there from apples to branches to whole tree limbs. Much of that would remain on top of the earth, in fact, after the culvert and would be easier to clean up.

BTW: Yes the culvert pipe I'd use is the double-wall ribbed on the outside, smooth on the inside.

[chesterspal]

My vote is for two "used" utility poles across and deck with 2" White Oak.  Bridges don't cause problems whereas culverts overflow, clog up, & wash out.

Your pictures show a perfect example for a 10' or 12' bridge.

Great idea. When can you start  :laugh:.
Seriously, at my age, which might be about your age, I am in no position to be dragging telephone poles around. I agree the bridge is cleaner but the cost, in body damage, far exceeds it if I have another option.  

[chesterspal]

Do you have a sawmill? Is there one near you? Looking at how small a span, I'd be tempted to have some massive beams span the gap and be done with it. Something like 8x12, and run some 3/4 all thread to snug them up.

Yes, there are sawmills in the area, but my thinking is similar to the one above.

I also think building a bridge will require getting a permit, having an engineer design it, and getting the town to OK it. That will take months and in the end they can not approve it.

[doc henderson]

I would not think a simple line of planks across a 4-foot ditch on your land for private use would be regulated.  you can even put tele poles on the sides and do culver and fill with stone and dirt.  we have one 20 feet long for 20 years.

[peakbagger]

If you have the potential for frost in the ground, the "rules" are different. 

[Magicman]

With two culverts they will have to be sealed between them to keep water from blowing through.

And don't worry about "body parts".  I am 80 and offer no excuse.  Build da bridge.

[beenthere]

How many individual culverts would handle/equal or come close to the volume of one 36" culvert?
Think six 15" culverts will equal about the same as one 36".

Still need the location of the OP to give good info, IMO

[Ron Scott]

If this is usually a maximum 4-inch straight flow as you describe and you prefer not to bridge it, I would not use anything smaller than a single 18-inch metal culvert with a 1-foot berm on top. 

Rock rip/rap each end of the culvert.

[Magicman]

https://gegcalculators.com/culvert-flow-calculator/

[thecfarm]

A metal culvert has ribs in it, slowing the flow of water. The smooth bore plastic culverts allow the sand, gravel to go through, keeping the bottom of the culvert clean and smooth.

[Wlmedley]

Around here corrugated metal culverts don't last long.Don't know if it is the water or what but I put one between the house and barn and the bottom rusted out in about 10 years.

[thecfarm]

The town put a metal one in my driveway.
It was dug up this summer,22 years later. Yes, rusted out on the bottom.
I have no idea what the smooth bore one will look like in 22 years. There was a lot of sand and gravel in the bottom of it.
There is a smooth bore plastic culvert down the road that is nice and clean. 

[chesterspal]

I would not think a simple line of planks across a 4-foot ditch on your land for private use would be regulated.  you can even put tele poles on the sides and do culver and fill with stone and dirt.  we have one 20 feet long for 20 years.

Well, to be on solid ground on each side of this gulley means the "bridge" has to be around 16' long. Remember, I need this to support at least 6,000 lbs of weight. 

[chesterspal]

With two culverts they will have to be sealed between them to keep water from blowing through.

I have thought about that. 
Thinking about using rock dust between the two ribbed plastic smooth on the inside culverts. Rock dust tends to harden up after getting compacked and wet almost like cement.
The other option is to use cement between them. 

[chesterspal]

If you have the potential for frost in the ground, the "rules" are different.

Can you please explain?

[chesterspal]

The town put a metal one in my driveway.... There is a smooth bore plastic culvert down the road that is nice and clean.

The smooth-on-the-inside, double wall, HDPE plastic culvert is the only way to go.
They will support the weight needed, as long as they are buried and compacted properly and they will last a good, long time.
Easy to clean out... if they ever even need it.

[nativewolf]

I'll add that a single pipe of larger diameter is going to carry more flood water than 2 smaller pipes, side by side.  Buy a single 30" pipe or even a 24" pipe.  Position it correctly (need to prepare a good bed so the pipe is on a good surface).  Like chesterspal say, it helps to compact the material around the culvert.  I also agree with him on the double wall HDPE pipe vs metal.  Stronger, better flow, won't rust.  Keep the ends covered with rock or wood to keep sunlight off the ends.

[rusticretreater]

A large diameter pipe works better than multiple small diameter pipes.

You might consider a D shaped culvert.  It is made to meet conditions such as yours.