Flashboard riser installation
Posted: Wed Aug 19, 2020 12:24 pm
Looking for some do's and don't's of flashboard riser installation.
A little background:
This is a low field alongside a ditch that holds water annually. We've built a levee around the field, now it's time to install the pipe and riser. I've run the runoff calcs, time of concentration, the whole 9 yards. Ended up with a 36" pipe (this area drains a large hillside). Bought a steel painted riser from osceola machine for a plastic corrugated pipe. The soil where the impoundment is located is red clay, sometimes gray clay, so no issues with holding water. A problem with that dirt is it eats through metal quickly.
Most flashboard riser installs i've seen bury half of the riser into the levee. I'm worried that'll greatly reduce the life of my riser due to corrosion. I'm wanting to pull it out into the impoundment a few feet and have it stand alone. Now my next issue, that pesky buoyancy thing. Water will be 4' deep at full pool. Riser is 2' deep x 3.5' wide. that weight of water comes out to 1,750 lbs. Riser only weighs 185. Ideally, i'd pour a big chunk of concrete and anchor it to the concrete, but i doubt we can get a concrete truck back to that area. I've also considered anchoring it into the soil using auger-style anchors.
My most recent idea is to put the riser on the back end of the pipe, outside of the levee. It'd basically be turning the system around backwards. Water flows in the pipe first, then through the riser and over the boards. No buoyancy problems then but water will be trying to push the riser off the pipe and once a stick gets in there, it won't be able to escape (unless there' s a big rainfall event) until i pull a board or two. Beavers are around, so i'll install a hog wire fence guard around the inlet. Also planning on putting in a seep collar.
Anyone ever seen a flashboard riser installed outside of the levee?
A little background:
This is a low field alongside a ditch that holds water annually. We've built a levee around the field, now it's time to install the pipe and riser. I've run the runoff calcs, time of concentration, the whole 9 yards. Ended up with a 36" pipe (this area drains a large hillside). Bought a steel painted riser from osceola machine for a plastic corrugated pipe. The soil where the impoundment is located is red clay, sometimes gray clay, so no issues with holding water. A problem with that dirt is it eats through metal quickly.
Most flashboard riser installs i've seen bury half of the riser into the levee. I'm worried that'll greatly reduce the life of my riser due to corrosion. I'm wanting to pull it out into the impoundment a few feet and have it stand alone. Now my next issue, that pesky buoyancy thing. Water will be 4' deep at full pool. Riser is 2' deep x 3.5' wide. that weight of water comes out to 1,750 lbs. Riser only weighs 185. Ideally, i'd pour a big chunk of concrete and anchor it to the concrete, but i doubt we can get a concrete truck back to that area. I've also considered anchoring it into the soil using auger-style anchors.
My most recent idea is to put the riser on the back end of the pipe, outside of the levee. It'd basically be turning the system around backwards. Water flows in the pipe first, then through the riser and over the boards. No buoyancy problems then but water will be trying to push the riser off the pipe and once a stick gets in there, it won't be able to escape (unless there' s a big rainfall event) until i pull a board or two. Beavers are around, so i'll install a hog wire fence guard around the inlet. Also planning on putting in a seep collar.
Anyone ever seen a flashboard riser installed outside of the levee?