Drainage ditch construction

[DJB132]

My brother has a road going up a hillside that needs a drainage ditch so the runoff doesn't wash out the roadway.

The road is fairly steep so my idea is to put down some stone in the ditch, lay down perforated pipe w/ cloth wrapped around it to prevent soil infiltration & then cover the pipe with more stone. My theory is that this will do a better job of preventing erosion than just lining the ditch with stone.

Any comments or suggestions are appreciated.

Thanks,
David

 

[JB4310]

Usually you wouldn't need a pipe on a steep slope unless your going under the driveway.

Larger stone 3-4" and up (Riprap) will prevent erosion, but typicaly a drain ditch like your describing would just be cut out and left alone.

http://www.stormwaterauthority.org/assets/Riprap.pdf

http://www.tennessee.gov/environment/wpc/sed_ero_controlhandbook/rr.pdf

JB.

 

[MarkV]

My brother has a road going up a hillside that needs a drainage ditch so the runoff doesn't wash out the roadway.

The road is fairly steep so my idea is to put down some stone in the ditch, lay down perforated pipe w/ cloth wrapped around it to prevent soil infiltration & then cover the pipe with more stone. My theory is that this will do a better job of preventing erosion than just lining the ditch with stone.

Any comments or suggestions are appreciated.

Thanks,
David

David is the road cut into a hill side? If so I think what you will find is that even with the stone and piping that enough silt will come off the hill side to eventually cover the stone. In heaver rains the covering silt will cause the water to run off on to the road before it can work its way to the pipe. And, you will have a heck of a time cleaning out the ditch with the stone and pipe in there. Every ditch will need cleaning eventually.

I think you will be better off if you can get a good crown on the road to divert the water to open ditches which lead to culverts or areas where the water can be diverted away.

MarkV

 

[DJB132]

JB - Thanks for the info

MarkV - The road is cut in at an angle to the hill, with earth above it on the right side. The road surface is pitched towards the hillside.

If we just cut a ditch in, won't we have to worry about undercutting the hillside?

 

[Egon]

With the steep hillside ditch there may be erosion from the water running down the ditch.

Sometimes straw bales are placed across a ditch at intervals to slow the rate of water flow down.

In the situation you have described placing some of these bale restrictions as well as installing culverts to divert water to the downhill slope of the road may be considered.

The object is to slow the rate of water flow down so that it cannot carry material and erode the ditch.

 

[EddieWalker]

My brother has a road going up a hillside that needs a drainage ditch so the runoff doesn't wash out the roadway.

The road is fairly steep so my idea is to put down some stone in the ditch, lay down perforated pipe w/ cloth wrapped around it to prevent soil infiltration & then cover the pipe with more stone. My theory is that this will do a better job of preventing erosion than just lining the ditch with stone.

Any comments or suggestions are appreciated.

Thanks,
David

Sounds like you are describing a french drain with the pipe and fabric. Every french drain will fail. It's just how long until the fabric gets covered with material and stops allowing water through it. For a road ditch, I would guess that it will fail fairly quickly. There is just too much debris that will end up in the ditch.

I like the use of rock. It will both protect the soil from erosion and slow down the speed of the water as it flows through the ditch.

The bigger you make the ditch, the more water it will handle and the slower the water will flow. Look at how the county does their roads and try to copy it. They are the standard and what you should be trying to copy.

Good luck,
Eddie

 

[JB4310]

With the steep hillside ditch there may be erosion from the water running down the ditch.

Sometimes straw bales are placed across a ditch at intervals to slow the rate of water flow down.

In the situation you have described placing some of these bale restrictions as well as installing culverts to divert water to the downhill slope of the road may be considered.

The object is to slow the rate of water flow down so that it cannot carry material and erode the ditch.

I think the bales idea could help as long as they were not blocking the channel acting as a dam, which might allow water to spill over the road/driveway, the culverts would be the ideal situation, every 100 ft or so.

If there is native stone on this hill use to line the trench and build up around the inlet and outlets of the culverts.

JB.

 

[Egon]

[I think the bales idea could help as long as they were not blocking the channel acting as a dam, which might allow water to spill over the road/driveway, the culverts would be the ideal situation, every 100 ft or so./QUOTE]

First the ditch has to be deep enough so the bales fit. Then they do act as a dam. They have a tendency to stop the flow of water. This effectively slows it down so it can't erode the bottom. When there is a lot of water it overflows the the bales.

It's a very common procedure used in ditches.

 

[woodchuckie]

When I'm working the trails I've made I avoid ditches as much as possible. I grade the road to get the water to flow off to the low side. once that water is off it's not a problem anymore. I may have a ditch for a very few feet before I send it on down hill off the side. This may be similar to the way loggers do their logging roads except I don't pile up the water bars, I cut a shallow dip to take the water away. I use the same principle on my driveway and don't have to work it till two or three years later.

 

[bearmtnmartin]

the usual way is to use a hoe and dig as deep a ditch as is practical and then heel in a good layer of 6 inch clear or thereabouts. (good size fractured rock that will knit). You can line the high side quite a way up the slope. This does take a little skill though. Don't need pipe.