River intake silt removal 1

[davecrimp]

On the Umpqua River of western Oregon...
To seasonally start up a 6,600 gpm self cleaning fish friendly drum screen in early spring requires removal of several feet of river silt which covers the intake. It can't be manually dug out because, at the time of startup, there is about 12 feet of water above the intake.
Please see attached plan and section.

What is the best way to remove the silt?

We are considering installing fixed, 3" or 4" draft tubes down to the intake at EL 50 from the landing at EL 64. At the landing, operators could either (1) pressurize the draft tubes to blow out sediment from around the intake, or (2) suck out rocks and sediment using a diaphragm pump such as a Sandpiper.

Other ideas? Thanks.

 

[BigInch]

Blowing the se diment to where? Into the current and downstream isn't very fish friendly and I doubt it is allowed by Oregon's natural resource agency. Consequently you should plan on pumping it out with a dredging pump, separating the sediment and water and disposing of the sediment according to Oregon's regs. If its a navigable stream or wetland area, you must secure COE permits as well.

http://virtualpipeline.spaces.msn.com

 

[ltho98]

I'm not sure what your budget is.. but this a possible solution. I also don't know what kind of flow rate you need but here's my .02

Pump into a large tank and allow the sediments to fall out of suspension. Allow for settling time and pump the water out and fill again to backwash out the sediment through a different outlet.

Else, why not use parallel cloth bag filtration units, fairly inexpensive. What is the turbidity of the water?