Sizing Rip Rap Down stream of large dam spillway
Sizing Rip Rap Down stream of large dam spillway
(OP)
Working in Georgia. I've been asked to size a rip rap channel downstream of a large 16' tall concrete principle spillway. Spillway is the primary outlet control to a large golf course lake. Common practice for our company, during civil site work, for outflowing storm pipes is to use a Rip Rap (St) nomograph (see attached). My problem is that I have been informed by the dam design engineer that their Q100 is approx 30000 cfs with a Velocity (100 yr) of approx 9 fps. I cannot read from my attached chart with that high of a Q, let alone,... I'm not confident this is the best resource to pull from. This is traditionally for sizing rip rap pads for storm pipes with lower Q's. Can anyone help? Spillway's concrete chute is 25' wide. I'm not sure why the dam engineers did not spec this during their design.... but that is my dillema





RE: Sizing Rip Rap Down stream of large dam spillway
Do you have the book "Design of Small Dams"?
Mike McCann
MMC Engineering
RE: Sizing Rip Rap Down stream of large dam spillway
RE: Sizing Rip Rap Down stream of large dam spillway
RE: Sizing Rip Rap Down stream of large dam spillway
RE: Sizing Rip Rap Down stream of large dam spillway
RE: Sizing Rip Rap Down stream of large dam spillway
You can design riprap based on incipient motion and shear?
RE: Sizing Rip Rap Down stream of large dam spillway
RE: Sizing Rip Rap Down stream of large dam spillway
You did not mention something about the slope of the rip-rap. The chart you attached is not the right one.
First sort out the allowable velocity using slope and flow capacity before you start to select stone sizes.
RE: Sizing Rip Rap Down stream of large dam spillway
Another consulting engineer recommends slurrying the rip rap and sizing it to larger than 24" dia stone.
Where do I find a reference to specifying stone that large?
Where can I get familiar, enough to specify...slurry operations. I know what it is, but apart from that...?
RE: Sizing Rip Rap Down stream of large dam spillway
You would have to divert and do in sections.
Intrusion Prepakt /marineconcrete.com
RE: Sizing Rip Rap Down stream of large dam spillway