PVC Pipe Drainage Question

[raydefan]

I am designing a drainage system for a parking lot using 12" PVC pipe. I have to have a couple of angles in my alignment, and want to know my options on how to do this. People in my office have different opinions. Some say to use a catch basin or clean out at all angle points in order to get access if the drain gets clogged. Others say that no access is required because a "snake" can be used to clean the pipe. This person said that there was some limitations on the length and total degrees of angle points between cleanout using this philosophy. What do you guys think?

 

[dicksewerrat]

If you don't use a Catch basin, only one bend persegment and try not to use any more than a 45 degree bend.

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[LHA]

A snake on 12"? Anything big enough to clog that is going to take a heck of stiff snake, which will take Governor Swartzenegger to push it, unless a truck can get down to the outlet, which is not always the case. On the other hand, it will be almost impossible to clog, provided your inlets are protected and your pipes can self-scour.

If the pipe is fed by standard rdl's, everything in the 12" will be under 12" anyway, so you are OK. If fed by grated inlets, everything in the 12" will be under 12" anyway, so you are OK. If fed by an open endwall, you'll need a trash rack on the inlet endwall, then everything in the 12" will be under 12" anyway, so you are OK.

Throw an O&M note on the plans requiring vaccuum cleaning of the inlets when sediment reaches 6" deep, if you have them. If you have an NPDES permit, O&M will be required.

If the pipes can't be laid at a slope to proved scouring velocity of 2.5 fps, you need some way to flush the pipes, and a cleanout is probably the cheapest. Careful though, 12" PVC fittings are expensive. An inlet, if less than, say 5 feet deep, might just be cheaper.

Remember: The Chinese ideogram for “crisis” is comprised of the characters for “danger” and “opportunity.”
-Steve

 

[gbam]

Well said lha.