Minimum Pond Outfall Pipe Encasement

[gunslinger25]

Hello all,
I'm wondering if anyone has any information on what the minimum length a pond outfall pipe has to be concrete encased. I'm in Maryland and haven't found anything in the MD 378 Pond Spec, but I may be looking in the wrong place. Also, my boss seems to think it is a national standard. Any help would be appreciated.
-Jay

 

[sam74]

Never heard of it in the sense it sounds like your talking about. Sounds like you mean the end of the pipe?

What I have heard of is an anti-seep collar in the midst of the berm around the culvert to prevent erosion along the pipe.

In my area we just backfill the culvert with clay and slap on a precast headwall.

 

[TerryScan]

I think you are referring to a cradle vs. encasement.

From Maryland's Stormwater manual, Appendix B1 (Pond Code 378) page Pond MD-378-16:

2. Bedding - Reinforced concrete pipe conduits
shall be laid in a concrete bedding /
cradle for their entire length. This bedding
/ cradle shall consist of high slump
concrete placed under the pipe and up the
sides of the pipe at least 50% of its outside
diameter with a minimum thickness
of 6 inches. Where a concrete cradle is
not needed for structural reasons, flowable
fill may be used as described in the
“Structure Backfill” section of this standard.
Gravel bedding is not permitted.

 

[BelspringKen]

I think Terry is right. I have worked on jobs requiring the pipe cradle for the RCP.

Is the cradle there to keep the sections of pipe from "parting company"?

As far as I know, its not a national standard, but it is used in MD and DE.

 

[dicksewerrat]

We used asphalt coated bolts to hold the pipes together. But prpoer bedding and a cutoff wall to prevent scour at the end of the pipe helped.

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[rconner]

you may also be interested in perhaps arguably some similar application I noticed some time ago discussed at

http://www.nwk.usace.army.mil/local_protection/pdf/pipe.pdf