Really long culvert ideas?

[Oaktree]

Hope it doesnt clogg. There is at least 1 access hole about half way.

That was my concern with a culvert as long as the OP proposed. Dunno what the soil is like in Texas, but here we have a lot of fine, silty sand that tends to clog culverts unless there's a really high pitch (not always possible). Lotsa luck cleaning that out of a 90' or longer pipe!!

 

[oosik]

You guys and your rainfall. I have a very accurate rainfall gauge here on my weather station. I have recorded the highest rainfall, in a 24 hour period, that we have had in the past twenty years. 0.76 inches of rain.

If this area EVER saw anything like eight inches in a 24 hour period - - even I might be convinced the rapture was upon us.

We can go year after year and never see eight inches of rainfall for the entire year.

Eight inches would produce flooding like only experience in pre-history, when the ice dams went out on ancient Lake Missoula.

 

[EddieWalker]

I have a 72’ x 300’ building (indoor arena and barn. My entire property slopes from the southwest down to the north east so we had to build up the whole north 72’ end quite a bit. The difference between the east and west corners is about 7’. Since there will be 2 aisle ways, we have 2 entrances. Obviously the NE entrance is much steeper which we’d like to fix, but first I have to put in some sort of culvert to allow the ditch along the west side of the building a place to drain without funneling it into storage sheds.

We’re talking probably a 90’ long culvert that has to withstand tractors and such. Culverts are so dang expensive! A 12” x 20’ HDPE corrugated pipe is like $250 and it probably needs to be a bigger diameter than that too. Any cheaper options?

View attachment 605919

McCoys has 12 inch culverts for $160 if you have one near your location. Lowes also sells them for about the same price. Shop High-Quality Plastic Culvert, 12" X 2' at McCoy's


The longer you go with a culvert, or any drain pipe, the harder it will be to keep it clear. You need a lot of slope to keep a long pipe clean.

French drains are a huge waste of money that always end up failing.

Nothing is more reliable, or cost effective then a ditch. Make it as wide as possible so it's barely noticeable, and easy to mow. Think about how the roads are built, they rely on ditches on either side.

Where you have to have culverts, look at what is used in your area that will be similar to what you will have to deal with during the worse case scenario. For me in East Texas, I've had several storms over the years of 5 inches in a day. I have 12 inch culverts in some areas on my land that can handle this, but I also have 15 and 18 inch culverts in other areas as more and more water accumulates in the lower areas of my land. The County required a 24 inch culvert for my driveway.

 

[4570Man]

You guys and your rainfall. I have a very accurate rainfall gauge here on my weather station. I have recorded the highest rainfall, in a 24 hour period, that we have had in the past twenty years. 0.76 inches of rain.

If this area EVER saw anything like eight inches in a 24 hour period - - even I might be convinced the rapture was upon us.

We can go year after year and never see eight inches of rainfall for the entire year.

Eight inches would produce flooding like only experience in pre-history, when the ice dams went out on ancient Lake Missoula.

Here’s a picture I took of a job I was going to do. After I decided the 4’ culvert they wanted was grossly inadequate I decided to pass. I don’t know how much water fell that night but it was a lot.

 

[RedNeckRacin]

The only proper way to size a culvert is to analyze the drainage area. It may be worth finding someone who specializes in this (a civil engineer) or someone who does site development. Looking around the area or arbitrarily choosing a culvert size is guessing at best. You may be surprised at how much water a 6" smooth walled pipe will move. I'm very skeptical that a 12" pipe is needed around a building but I'm not there nor have i done an analysis. Eddie is correct about needing some fall to scour the pipe to keep it clean unless you have inlet protection for it. Access ports would be a good idea if you start getting over 100' long. Water has a funny way of being a pay me now or pay me later type deal.

 

[Tractor Seabee]

Just remember to calculate the maximum amount of water to expect and add a fudge factor.
Last year, Sep 21-22, 2018, DFW reported 8.11 inches of rainfall. That's a respectable amount of rain for one day.

Lot of good ideas here to pick from.

Just remember; double the diameter=4 times the volume. Going from 12" to 24" is the same as 4 12" culverts side by side. Do the math.

Have an accessible manhole/clean-out at every bend of the pipe and no further than each 100' of run. Trash and silt collection at the beginning will save much frustration later. Try to unclog a tangled mess 100' away is no fun, dynamite time.

Ron

 

[4570Man]

Just remember; double the diameter=4 times the volume. Going from 12" to 24" is the same as 4 12" culverts side by side. Do the math.

Ron

I’ve done the math before and based on surface area you’re right, but I’m guessing double the diameter flows more than 4 times as much. Also the smooth wall pipe aka double wall pipe flows way more than corrugated or galvanized pipe.

 

[Tractor Seabee]

I’ve done the math before and based on surface area you’re right, but I’m guessing double the diameter flows more than 4 times as much. Also the smooth wall pipe aka double wall pipe flows way more than corrugated or galvanized pipe.

That formula is a basic premise. Yes you still have to subtract for actual ID and friction losses. That was our pipe fitter job-site engineering factor. The larger the pipe the less small details affect the end result. I doubt the average TBN DIYer is an engineer. Sheet metal workers use the same formula for on-site rough calculations on airflow.

I was a journeyman at both trades. We have had engineered drawings that at a quick glance were obviously wrong when adding up the flows. I never lost one of those arguments with the engineers.

Ron

 

[EddieWalker]

... Going from 12" to 24" is the same as 4 12" culverts side by side. Do the math...

The math that I was told by the water department people relates to residential drain lines, and for every half inch increase in pipe diameter, you doubled what would flow through the pipe. I never checked it to be sure since PVC drain lines in houses are so cheap and you just do what code requires without any real thinking involved.

For culverts, the more you have next to each other, the more issues that you will have with them. One big pipe is always a better choice then several smaller ones. The most obvious issue with the smaller pipes is stuff blocking the inlet side of the pipe. But the bigger, more concerning issue is erosion between the pipes that leads to catastrophic failure. It's VERY HARD to install two pipes next to each other and get good compaction between the pipes. For this reason alone, it's something that should be avoided.

 

[piaffepony]

The math that I was told by the water department people relates to residential drain lines, and for every half inch increase in pipe diameter, you doubled what would flow through the pipe. I never checked it to be sure since PVC drain lines in houses are so cheap and you just do what code requires without any real thinking involved.

For culverts, the more you have next to each other, the more issues that you will have with them. One big pipe is always a better choice then several smaller ones. The most obvious issue with the smaller pipes is stuff blocking the inlet side of the pipe. But the bigger, more concerning issue is erosion between the pipes that leads to catastrophic failure. It's VERY HARD to install two pipes next to each other and get good compaction between the pipes. For this reason alone, it's something that should be avoided.

I’ve dug ditches to help divert water around the lower barn and various other things after we’ve expanded and built more crap that changes the water flow. I’m in North Texas where it’s all or nothing when it comes to rain. Several inches all at once for weeks then 2 months of drought. Erosion is a constant battle with my Texas black gumbo soil and horses . Ditches always seem to fill up quick with soil.

I will never use side by side pipes for this very reason. Our soil moves way to much! This is why I was wondering if there were any cheaper options other than one giant pipe... like 55 gallon HDPE barrels or something (that i can get for free) lol.