# Determining culvert size



## Flaustin1 (Apr 6, 2015)

I just bought my first piece of property and wanna get started clearing/cleaning it up asap.  I have to put a driveway in first.

The drive is going to cross a creek which is only about 4ft wide at the widest.  About 2 ft where the drive will cross.  It has steep/sheer vertical banks about 3 ft tall.  

How do I determine the pipe size.  The creek shows no sign of flooding and getting out of the banks.  Im thinking a 24" pipe should handle it.  What do yall think?


----------



## OmenHonkey (Apr 6, 2015)

Just my .02 but the problem I have had in the past isn't the amount of water moving through the pipe it's the debris build up while your not there that usually causes a blow out. I have better success with tapering the slopes and back filling with large then small gravel. Also I have not seen your situation and they can of course vary greatly. Also look into a bridge PT 6x6's and some other good lumber would easily handle that span with ease unless your moving big equipment in.


----------



## j_seph (Apr 6, 2015)

how deep is creek


----------



## j_seph (Apr 6, 2015)

The idea of grading and making a gravel drive sounds like the est option


----------



## T-N-T (Apr 6, 2015)

Biggest pipe that will fit without digging.   Then fill gravel and dirt. Water is coming.   Might as well give it a nice hole to flow through.   And,  no need to dig out and have a low area that gets soft when it rains.


----------



## rip18 (Apr 6, 2015)

Some good observations above...especially about debris build up.

Span bridges can be good options that don't impede water flow and "usually" don't catch debris.

Low water crossings are fantastic - as long as you or emergency responders  don't need to get across (in OR out) during high water.  http://www.fs.fed.us/eng/pubs/pdf/LowWaterCrossings/Hi_pdf/6_Chapter5.pdf

There isn't enough information here to properly size a culvert (or culverts).  The main determinant of how large a culvert is needed is how large an area flows through that location (watershed size).  Pair the watershed size with soil type (larger-particled soils have higher infiltration rates) and maximum 24-hour rainfall, and you can then estimate the size of culvert you need....

http://warnell.forestry.uga.edu/service/library/b1083/node30.html

Good luck!


----------



## Flaustin1 (Apr 6, 2015)

Thanks guys, We have thought about a span bridge.  Rip18 that's a helpful link.  Thanks again.


----------



## OmenHonkey (Apr 6, 2015)

Check you local welding shops. You'd be surprised what kinda stuff they have laying around from something damaged that might fit the bill. I have seen old trailer frames fixed into nice bridges on the cheap!!


----------



## Milkman (Apr 6, 2015)

Flaustin1 said:


> I just bought my first piece of property and wanna get started clearing/cleaning it up asap.  I have to put a driveway in first.
> 
> The drive is going to cross a creek which is only about 4ft wide at the widest.  About 2 ft where the drive will cross.  It has steep/sheer vertical banks about 3 ft tall.
> 
> How do I determine the pipe size.  The creek shows no sign of flooding and getting out of the banks.  Im thinking a 24" pipe should handle it.  What do yall think?



Talk to someone at your County Road Dept.  They are experts on the situation you describe. 

Of course they wont do the work since it is on private property. But they do that kind of work routinely and can advise you on what will last vs what will wash out next winter.


----------



## BriarPatch99 (Apr 6, 2015)

Old mobile home frame overlayed with 3" or so planks ....


----------



## T-N-T (Apr 6, 2015)

BriarPatch99 said:


> Old mobile home frame overlayed with 3" or so planks ....



You would be surprised how many of these I see around.
Start looking and I bet you run up on one on your driving around.


----------



## DCHunter (Apr 6, 2015)

I'm a civil designer. Give me an address or latitude and longitude and I can give you exact options.


----------



## tree cutter 08 (Apr 6, 2015)

We have 4 crossings on our drive. 3 24inch and a 3 ft pipe. Do yourself a favor and put in a plastic culvert. Not much more and will outlast galvanized.  Need to clean out topsoil around creek and clean out creek bottom to bed the pipe. Only use good dirt when covering. Tamping and packing as you go. I like about 2 ft or more of dirt on top of pipe.  Also need to consider how much watershed is above you. Probably have that 1 and 100 year rain event after you put it in so you want one big enough. A 3 ft pipe will handle a lot of water.


----------



## Flaustin1 (Apr 6, 2015)

Long,lat.  34.447291,-83.010567.  Greatly appreciated too by the way.


----------



## DCHunter (Apr 6, 2015)

Flaustin1 said:


> Long,lat.  34.447291,-83.010567.  Greatly appreciated too by the way.



I'll let you know something by around lunch tomorrow.


----------



## Flaustin1 (Apr 6, 2015)

Awesome!  Thanks a million.


----------



## DCHunter (Apr 7, 2015)

I sent you a private message.


----------



## 7Mag Hunter (Apr 7, 2015)

Next door neighbor filled 4' ditch with 2 -
culverts approx 16" in diameter, and everytime it rains
 hard for a few days water spouts out of the ground 
about 3' from his driveway....He is
just about to have a sinkhole between his
driveway and mine !!!!!!

My advise is go BIG.....Put the biggest culvert pipe you 
can fit in the creek, and use gravel/dirt to level out for drive...


----------



## Flaustin1 (Apr 7, 2015)

It looks like im going to have to put in a bridge.


----------



## T.P. (Apr 7, 2015)

What are you planning on using the bridge for? A permanent crossing or just to drive equipment across?


----------



## T-N-T (Apr 7, 2015)

The creek/ditch is there for a reason.  Gotta keep it as open as you can...

Good luck with your bridge!


----------



## Flaustin1 (Apr 7, 2015)

I guess I will build it in place.  My pops has all the equipment to do it.  Concrete footers to anchor to with large structural I beams and C-Channel as the load bearing structure.  Not sure what to "deck" it with though.


----------



## T.P. (Apr 7, 2015)

I'd personally build it just like a trailer. Throw two W12x14's across the span, then some C5x6.7's for cross members then deck it with treated 2x's.

That's way overkill but if you put footings in the span will be longer that what you have now.


----------



## shakey gizzard (Apr 7, 2015)

Build it 3x what the pro's are say'n!


----------



## tree cutter 08 (Apr 8, 2015)

Might consider decking it with white oak 2x's. They seem to hold up longer on my equipment trailer than pressure treated pine.


----------



## Flaustin1 (Apr 9, 2015)

Im gonna have to put a pipe in temporarily.  I don't want to build a bridge that can support a concrete truck, pump truck, big flatbed etc.  Will build the bridge after the house is built.


----------



## Gaducker (Apr 9, 2015)

Some one in Newnan has a 30 inch iron culvert pipe for sale   30 inch x 20 ft long for 500 bucks   its on craigslist.  search Ductile Iron Pipe 30"x20'


----------



## GunnSmokeer (Apr 9, 2015)

That sounds expensive.

I bought two 20-foot sections of 18" diameter pipe to cross a big ditch (10 feet deep, 15 feet wide) that has a little stream in it (only a couple inches of water, 2 ft. wide, barely moving. Even after a day of heavy rain, I've watched it, and it doesn't get more than twice that high or deep.

I paid $60 for each length of that pipe. New, but old from storage outdoors. Faced and some corrosion, but not dented and never buried.

However, I did not actually use those pipes yet because of the huge amount of dirt and rock and then more dirt that I'd need to fill in the space around them. Probably 10 loads of a full-sized dump truck.

I also considered buying used, but good condition, railroad cross-ties and building a bridge out of them.  They're 9 feet long each, and I could have a center bridge support with a concrete base, holding up a set of 4 of these beams to support the middle of the bridge (two beams where each set of vehicle tires would go). The rest of the bridge would be made of joists using other RR cross ties, and the decking would be 8 ft. pressure treated landscape timbers that are 2.5" thick ($2 each, compared to the more conventional 2x6" boards that are only 1.5" thick and cost $5.70 per board).

I've driven over bridges made with railroad cross ties before, and they're solid. 

P.S. there is some significant cost in the long bolts needed to assemble this bridge, though.  I might consider  not trying to attach these cross ties directly to each other, but instead to use ordinary dimensional lumber around them to hold 'em in place, using 3.5" coated deck screws through the tw0-by lumber and into (but not through) the crossties.


----------



## Gaducker (Apr 9, 2015)

That's a ductile iron pipe in Newnan and it looks to be 2 inches thick.


----------



## Scrapy (Apr 9, 2015)

What did DC Hunter come up with? That's what civil engineers go to school for 4 years for. There is a good bit to it. rip18 also gave a good link for doing it yourself. You would probably find that mapping out the watershed on the ground would be fun. Might could even do it off a topo and soil maps  if the area is hilly enough.


----------



## tree cutter 08 (Apr 9, 2015)

I'd go overkill on the bridge if it was me. Never know when u may need a fire truck, dumptruck, bucket truck, or any other big trucks down the road. I still think the culvert pipe is the best route. I've seen a few small bridges on driveways that I woukdnt drive a ton truck across. Just something to think about.


----------



## calibob1 (Apr 9, 2015)

40 foot flatbed trailers are dirt cheap and make a good bridge.


----------



## GunnSmokeer (Apr 9, 2015)

Yeah, and flatbed trailers can carry really heavy loads. Rolls of steel that weigh 35,000 lbs.

Or all that freight on wooden pallets? Sometimes a pallet will weigh 3000 lbs and it gets lifted by a 10,000 lb. forklift.


But back to culverts for a second, and water flow...

This book, although old, has some calculations about pipe size and water flow. 

http://tinyurl.com/Gunsmoker

It says that if a 24" pipe is tipped down so the lower end is 1 inch below horizontal (over a 100 foot distance), water will flow at 4 m.p.h. and the pipe will carry 2300 gallons per minute.

If that same pipe is angled so that it drops 3 feet over a 100 foot run, now the water will flow at 22 m.p.h. 
A 24" pipe with that fast-flowing water will handle up to 14,500 gallons per minute.

Now then, how can you calculate the water flow in your little stream?

How about measuring the width of the water, the depth of the water, and an estimated cross-section of the stream channel (cross-section) including angles of the slope of the sides.

Then put your numbers in here and let it calculate the volume & discharge for you.  
http://www.eng.auburn.edu/~xzf0001/Handbook/Channels.html
...


----------



## Flaustin1 (Apr 10, 2015)

Yall have been a lot of help.  Thanks.  DCHunter said due to the watershed this creek flows into(appx 150 acres) and the rainfall history for the area, 2 24" pipes may not handle the really big rains that we can get.  He suggested a bridge as well.  He put it in a lot more technical terms than I did but that was the jist of it.


----------



## DCHunter (Apr 10, 2015)

GunnSmokeer said:


> How about measuring the width of the water, the depth of the water, and an estimated cross-section of the stream channel (cross-section) including angles of the slope of the sides.
> 
> Then put your numbers in here and let it calculate the volume & discharge for you.
> http://www.eng.auburn.edu/~xzf0001/Handbook/Channels.html
> ...



You don't size a pipe based on just what the creek is. It surely flows from a spring and the amount of water coming out of that spring has nothing to do with how much water would be flowing through there with a good rain storm. Every situation is different based on drainage area, vegetation type, amount of impervious area, fall of creek etc. So you can't compare what worked for one persons situation and apply it to another situation. He could pipe it, but the size pipe he would need to handle a 100 year storm would too big and costly to be worth it.


----------



## DCHunter (Oct 2, 2015)

Flaustin1, this weekend will be the perfect opportunity for you. If the weather report is right, you'll be getting rainfall that will be close enough to a 100 yr event. If you can, go check out how that water is flowing in that creek bank after its rained a good bit. See how far up the banks it goes, or if it tops over. If you can, let me know what you observe.


----------



## jimbo4116 (Oct 2, 2015)

DCHunter said:


> Flaustin1, this weekend will be the perfect opportunity for you. If the weather report is right, you'll be getting rainfall that will be close enough to a 100 yr event. If you can, go check out how that water is flowing in that creek bank after its rained a good bit. See how far up the banks it goes, or if it tops over. If you can, let me know what you observe.



It want take but a few fallen branches in a swollen creek to negate the best of calculations as to the size of a culvert needed.  Better check around before starting in construction on a flowing branch or creek.  Big Brother has RULES.


----------



## Old Crusty (Oct 4, 2015)

jimbo4116 said:


> It want take but a few fallen branches in a swollen creek to negate the best of calculations as to the size of a culvert needed.  Better check around before starting in construction on a flowing branch or creek.  Big Brother has RULES.



^^^^^ This^^^^^^^
  You better tread lightly. Especially since you wisely put the coordinates on here.


----------



## DCHunter (Oct 5, 2015)

jimbo4116 said:


> It want take but a few fallen branches in a swollen creek to negate the best of calculations as to the size of a culvert needed.  Better check around before starting in construction on a flowing branch or creek.  Big Brother has RULES.



Yeah, the rules are to size it for a 100 year rain event. In his case would be about a 72" pipe. So that's why i told him it would be better to just bridge over it.


----------



## Flaustin1 (Oct 5, 2015)

jimbo4116 said:


> It want take but a few fallen branches in a swollen creek to negate the best of calculations as to the size of a culvert needed.  Better check around before starting in construction on a flowing branch or creek.  Big Brother has RULES.



I checked.  County, Corps, and EPD.  No permits were necessary for installing a culvert as long as it was installed  in a manner that made the driveway cross at a 90 degree angle.


----------



## Flaustin1 (Oct 5, 2015)

DCHunter said:


> Flaustin1, this weekend will be the perfect opportunity for you. If the weather report is right, you'll be getting rainfall that will be close enough to a 100 yr event. If you can, go check out how that water is flowing in that creek bank after its rained a good bit. See how far up the banks it goes, or if it tops over. If you can, let me know what you observe.



I didn't make it over there this weekend but I did install a temporary culvert to allow access to the property to do the underbrushing, cleanup etc.  It was 24" diameter.  Gonna go by there wed. morning when I get off work and see if its still there.


----------



## shakey gizzard (Oct 9, 2015)

Flaustin1 said:


> I didn't make it over there this weekend but I did install a temporary culvert to allow access to the property to do the underbrushing, cleanup etc.  It was 24" diameter.  Gonna go by there wed. morning when I get off work and *see if its still there*.



Should be interesting! Don't forget the pics!


----------



## Flaustin1 (Oct 9, 2015)

Well, the pipe is still there, but 24" ain't enough! It washed out.  I'm not sure if the pipe clogged then backed up the water and overflowed or if the pipe just couldn't handle it.  Below the pipe, the creek never came out of the bank.  Above it, it did.


----------



## DCHunter (Oct 9, 2015)

The pipe couldn't handle it. Never stood a chance.


----------



## Flaustin1 (Oct 9, 2015)

Nope, gonna build a bridge.


----------



## JustUs4All (Oct 10, 2015)

Flaustin1 said:


> Im gonna have to put a pipe in temporarily.  I don't want to build a bridge that can support a concrete truck, pump truck, big flatbed etc.  Will build the bridge after the house is built.



 After your home is built the bridge might still have to accommodate a septic tank pump truck or, God forbid, an ambulance or fire truck.


----------



## Flaustin1 (Oct 10, 2015)

Box culvert maybe?


----------



## Timberchicken (Oct 10, 2015)

Will you be hauling any timber out in the future? If so bridge needs to be strong.


----------



## tree cutter 08 (Oct 10, 2015)

Just go over kill on the culvert. I think it will be a lot cheaper than a bridge and permanent if done right.got 4 on our drive and had dump trucks, well trucks and cement trucks in and out over 100 times with out any trouble.if height is a issue go 2wide or 3 wide. A good head wall wouldn't hurt.


----------

