Definition of dam 3

[tsli001]

Hi there:

Currently I am working on a job that there are two ponds are side by side a 2 lanes roadway. The drainage guy believe one of the pond consider is a dam base on two conditions. 1=it is a 8' deep pond. 2=inflow rate is more than 50 ac-ft. Me and other senior engineer dont think so. And, I think that the drainage guy should look into other things to consider as a dam. I was wondering anyone got any suggestion that what should the drainage guy should look into?

thanks

tsli

 

[civilman72]

I believe each state has their own requirements in how/when they define a fill berm as a "dam."

Here in Colorado, if your detention berm is 10' or higher, it would be considered a dam.

Here is a link:

http://water.state.co.us/damsafety/damguide.pdf

 

[cvg]

I believe that in nearly every state, it would be considered a "regulatory dam". That means you will need a permit from the state to construct and operate it and that permit is not an easy thing to get.

http://www.damsafety.org/

 

[tsli001]

I see, so anything build higher than certainly high consider 'dam'and there is no otherwise.

tsli

 

[cvg]

for small dams there are generally several things to consider.

Here is some general info from Arizona and I believe it is very similar in other states:

...jurisdiction over dams 25 feet or more in height or dams that store more than 50 acre-feet of water. Some dams are
excepted from jurisdiction, including (1) barriers less than 6 feet in height, regardless of storage capacity; (2)
barriers that have a storage capacity of 15 acre-feet or less, regardless of height; (3) any barrier for the purpose of controlling liquid-borne material; (4)any barrier that is a release-contained barrier; and (5) any barrier that is
owned, controlled, operated, maintained, or managed by the United States government as long as it is subject to a dam safety program that is at least as stringent as Arizona’s.


Look at the attached diagram from California which is identical to Arizona's.

 

[msquared48]

Some meandering thoughts on the subject:

Personally, I don't know of any beavers that have ever applied for or obtained a permit for one of their "dams"... And I've seen some pretty big ones.

If it's not navigavle water, then it's not regulated by the Corps of Engineers.

And there are "Check Dams" that are only 12" to 18" high...

SO...What is a "Dam".

Mike McCann
MMC Engineering

 

[cvg]

M^2
"If it's not navigable water, then it's not regulated by the Corps of Engineers."

Actually, the Corps regulates other "Waters of the US" that are non-navigable under Section 404. For instance, in the west there are many ephemeral streams (dry washes) existing in the desert that are regulated by the Corps. These streams may only see running water once or twice a year but are still regulated.

 

[msquared48]

cvg:

That's a new one on me.

I guess you can navigate it in a raft (or an inner tube) when it's running, huh.

Thanks...

Mike McCann
MMC Engineering

 

[francesca]

50 acre-feet is a volume (over 2 million cubic feet), not a flow rate. You seriously got 50 acre-ft stored behind an 8' berm? Are you in Kansas?