How would you fix this? Road washed out...

[XM16E1]

Had a flood and the road to my recreational property/gravel pit washed out. Culvert could not handle all the water and here is what's left. At the peak water was 4' above the road. I have a Bobcat T650 and E35 mini on loan from the dealership until my T770 and E50 arrive. The mini ex and my dump trailer got trapped behind the road. Water went down enough so it I was able to walk across the culvert and grab the mini ex. Figured eh, no problem I'll just track out there and move the gravel back.

Well, that was a mistake. Ended up getting stuck for 2 hours. The grader slid into the middle of the culvert and put a nice hole in the middle along with dislodging the uncovered end so its barely flowing any water through it now. Didn't have enough reach with the E35 to retrieve the washed out gravel and tracking out on it was an impossible. Just sunk and the tracks would stall.

I'm an amateur operator having only ran the mini ex for 12 hours and the skid steer for about 20.

My plan now is to go back after things dry out more, dig out the existing culvert, lay it flat again and install a patch over the hole I made. I was thinking about getting a pallet of bagged concrete and lining the exterior of the culvert with the concrete bags. Along with adding a second culvert running in parallel. Then cover everything back up with gravel/dirt.

 

[redman135]

Photos please.
Also how much rain in what time?
What is catchment area,ie is pipe large enough for most rainfall?
After you repair the culvert would a floodway avoid a future washout?

 

[rademamj1]

Hard to prepare for those 100 year flood events. Your plan makes good sense. I assume you have the excavator or backhoe. Wait until it dries out onsite. Dig around the culvert and extract the culvert pipe. Retrench and clear out all gravel fill and debris. Insure its deep enough and at proper depth. Replace the culvert pipe back into proper position.

Backfill gravel onto the pipe. Bring in new gravel if needed. You need to put 24 inches minimum fill ontop the culvert as holding weight. You can also use bags of concrete laid down before the gravel as you suggested. These will turn to concrete at first rainfall. Leave 15 inches uncovered at each end of the pipe.

Later when it fully dries out, build and pour custom made concrete end caps over the exposed 15 inches of pipe, to limit future erosion and provide additional heavy weight on each end of the pipe, to prevent washouts.

 

[oosik]

Let's face it guys. If, during the peak of the flood, the water was 4' OVER the road - that single culvert is not big enough to handle the next flood.

I would consider something more capable of handling flood level waters. One very large culver or perhaps a bridge or a redesign of the channel at that location.

In any case - the OP definitely need design assistance - on-site.

 

[Thomas]

Excavator with good reach to do the work and 2 least same size culverts or bigger also header.

 

[DJ54]

One culvert twice the diameter of the existing pipe will carry approx. 30% more water, than twin pipes of that existing pipe. Smooth bore, even more due to less friction of the corrugations. Also, twin pipes without sufficient footers and head walls, or grouting in between with low strength grout, will allow critters like groundhogs to tunnel in between, and eventually a hole to form from the top. Grouting can be tricky, because culverts need to be tied down, or plugged, and let fill with water, to keep them from floating, when grouting.

As mentioned, when an event happens like this, whether it's a 100, 250, 500, or 750 year rain, it will take a pipe out. If it's encapsulated in concrete, water will seek the easiest path, and wash somewhere else.

 

[Jstpssng]

Let's face it guys. If, during the peak of the flood, the water was 4' OVER the road - that single culvert is not big enough to handle the next flood.

I would consider something more capable of handling flood level waters. One very large culver or perhaps a bridge or a redesign of the channel at that location.

In any case - the OP definitely need design assistance - on-site.

:thumbsup: Just looking at the photo, that culvert looks woefully undersized. We calculate size by measuring the width and depth of the high water mark of the channel, (preferably upstream and downstream) then multiply to get the square footage required. Even that isn't enough sometimes...

 

[LouNY]

If the flowing water was 4 feet above the roadway from the looks of the picture it must have been quite wide also but not flowing fast.
With that much slow moving water culverts will not handle the load.
Reinstall your existing culvert or a new and larger one,
then construct your roadway as a spillway for the dam your road is,
if you have a section of the roadway 20 feet long a foot lower then the rest with preferably sloped and concreted faces
for the water to flow across without washing it out you will be able to handle a multitude more water then a culvert can.
Spillways or concreted crossing work better then culverts, especially if not subject to icing.

 

[WranglerX]

Build it as a "ford"....

If you have 4 ft of water, you are not going in or out anyway...

We actually have large ford across a county road that is high water across it during flood stages, but it has four 18 to 24 inch culverts under it for low flow season ... Is sort of a dam/spillway concept....

Dale

 

[ovrszd]

I don't see enough roadbed above the bottom of the drainage ditch to handle a culvert large enough to handle the runoff of a large rain.

I like Dale's idea the best.

If just want to return it to previous flood condition, reset your culvert and be done with it.

I like my flood stage water to cross the roadbed away from the culvert.