Discharge Structure

[BobThomasson]

I'm involved in a project where we will be piping about 6000 GPM of water into an existing drainage ditch. The ditch is on BLM land and I believe the project may fall under the jurisdiction of the US Army Corps of Engineers, and they will review the design. The existing ditch is about 15 feet wide by 15 feet deep and is dirt. Flow in the ditch is seasonal and ranges from nothing to about 10 feet of water - I don't as yet know the velocity or flowrates.

Can anyone tell me where I can find guidelines for designing the discharge structure into the ditch in order to prevent erosion, etc. We'll be working with a civil engineer, but I want to be an educated buyer and learn as much as possible in advance.

Thanks,

Bob

 

[TerryScan]

I would check for standard practices for your local NRCS office. BLM or whoever manages the ditch may have their own standards.

http://www.nrcs.usda.gov/technical/efotg/

The discharge you speak of is minor in relation to the channel you describe. Standard rip-rap outlet protection is probably what is called for. This would be a stone apron over geotextile fabric at the end of your discharge pipe.

 

[gbam]

The flow rate you are discharging into this channel is small, about 14 cfs. The outlet structure will depend on the outlet velocity which in turn depends on the pipe diameter. With that said a copouple of options will be available to the designer.
1. concrete lining
2. riprap lining (grouted or dumped)
3. siphon structure
ect.....

I would start with the local gov. entity to see what standards they have. Then I would look at design manuals from the Fed Highways Admin. and Army Corp. I do not have the web links handy right now or I would place links to them, just web search them. Look for HEC14 & 11 at FHWA. These may give some insight.

One other thought is that what ever you have designed make sure you look at the design storm for that channel to determine if this structure will be in place after the 100-year event or such.

I hope I answered your ?

 

[cvg]

try the following publications for plenty of information regarding the design:

FHWA Hydraulic Engineering Circular No. 14 - Hydraulic Design of Energy Dissipators for Culverts and Channels

or

BUREC Engineering Monograph No. 25 - Hydraulic Design of Stilling Basins and Energy Dissipators

 

[gbam]

CVG,
Does the BUREC have their publications online? If so, can you please post them here? I have searched many time but cannot find them.

Thanks in advance

 

[cvg]

all on here...

http://www.usbr.gov/pmts/hydraulics_lab/pubs/index.html

 

[gbam]

got it
Thanks