Need an innovative way to disperse concentrated stormwater??

[bbengineering]

Its not uncommon to have to design a stormwater system where you have to divert off-site stormwater around a site. For example, I am designing a site on the side of a mountain where, for storm quality purposes, I have to divert all runoff coming down off the hill around the site. The problem is that now I am channeling all of the water to a single point location. My question is, does anybody have some innovative way to disperse the collected runoff in a safe and undetrimental manner? I have used level spreaders and rip-rap aprons, but they don't work well enough. I have also used a partial spreader and infiltration galley system, but it ends up being a very expensive option. Any ideas are appreciated.

Bryan Nesteriak, P.E.
B&B Engineering

http://www.bbengrs.com

 

[gbam]

I have used a lateral weir to slowly let flow exit a collection channel. I have also used a weir at the end of a channel.

 

[bbengineering]

I don't have a collection channel to discharge to. The system is located on the side of hill where all storm water sheet flows down. That is what makes this tricky.

 

[TerryScan]

You mention you have used level spreaders, but they were not satisfactory. What was the configuration? One approach I thought would be to collect the runoff on the upslope end into a pipe. On the downstream end, the pipe would run to a releatively flat section of perforated pipe parrallel to the contour in a stone trench (lined with appropriate geofabric). The idea here is to allow the flow to "bubble up" through the stone trench to the surface in order to restablish sheet flow. (by your description, I am assuming you can achieve the necessary head).