Sediment pond design (another post about)

[SMIAH]

Background about the region where I live/work :
Statistical analysis reveal that 90% of storm event are equal or less than:
[ul]
[li]1 in of total precipitation[/li]
[li]Duration of 6 hours.[/li]
[/ul]
Then, 1 in of precipitation is a 2-year 1 hour duration rainfall runoff.

I'm trying to convince regulators (who are not hydrologists) that if you design a sediment pond based on a 2-year rainfall runoff (rainfall runoff exceeded only 10% of the time) and you try to minimize the outflow (detention over the maximum possible duration), you may get a sediment pond working 90% of the time (ok let's say 80%).

If you take care in the design process to check the area of the pond to ensure the settling of a particule of a certain size (e.g. 0.05 mm) + check the length/width ratio + minimum depth, you may increase the efficiency of this sediment pond.

They don't get this. They tell me that this kind of sediment pond will have a 60% efficiency, based on lab some test made in New Jersey.

I'm thinking of changing job

 

[cvg]

well, first step would be to obtain the study and determine if it has any relevance to your situation

 

[SMIAH]

Done. It has nothing to do with our climate, the abrasive we're using (snow), our soils, etc.

New Jersey's sand...

 

[beej67]

Well, you could start with Stokes Law and work your way forward, which is how many sediment pond sizing methods are done. The problem with that, is you start with an assumption that your grains are spheres, which is a very poor assumption when you get down to clays.

Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East -

http://www.campbellcivil.com

 

[SMIAH]

I don't go under 0,02 mm.