Water Quality Volume

[dgatlin]

I'm doing a project in a city with different standards than I am used to. The city sent me back some comments and one of them was simply "Calculate the Water Quality Volume and provide this volume." So I followed the GA Stormwater Manual and did the calculation, but it does not make it clear what I am supposed to do with the number when I get it (if anything). Is that the minimum volume my detention pond should be?

 

[gbam]

Is there anyone in your office you can ask? Or the stormwater reviewer?

 

[runoff]

dgatlin;

I have done many projects in Georgia. The water quality volume will be used in addition to the hydrologic calculation that you used for detention.

For example, if an underground detention is used, you will need to calculate the first flush water quality volume in addition to the detention volume because most municipalities want you to design that volume into the system. Then they require a water quality unit up front as a pretreatment to detention. It seems redundant but I don't make the rules.

I hope that helps.

 

[bigcat151]

In my part of Florida the water quality volume is the volume the pond must retain without discharging. For dry ponds the volume is percolated into the soils and anything in excess of that volume can be discharge through a control structure. For wet ponds the volume is typically released at a controlled rate through a small diameter orifice located at the normal (or seasonal high) water table in the pond.