Mixing Treated Stormwater with Untreated Stormwater - calculating TMDLs
Mixing Treated Stormwater with Untreated Stormwater - calculating TMDLs
(OP)
So if you are proposing a design that treats water in a separate pond and then discharges into a larger pond so that that water mixes with untreated water before it all discharges to the outfall - how do you treat the lbs/removed for total phosphorous and nitrogen? Is it the same straight calculation for that volume that was treated or is there some dilution effect going on when it mixes with untreated water? Has anyone addressed this properly via research and testing?





RE: Mixing Treated Stormwater with Untreated Stormwater - calculating TMDLs
If not, you already have your answer.
Do your best not to wade into the highly confusing morass of whether the discharge criteria should be in pounds per acre per year, or in concentration of pollutant. I did a project in South Florida where we were required to discharge water that was eight times cleaner than the undeveloped site, because we were held to a lb/ac/yr threshold instead of a pollutant concentration threshold, so our increase in volume of runoff hurt us instead of helping us. Lost that argument with SFWMD.
Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East - http://www.campbellcivil.com
RE: Mixing Treated Stormwater with Untreated Stormwater - calculating TMDLs
RE: Mixing Treated Stormwater with Untreated Stormwater - calculating TMDLs
If you're talking about converting some but not all of a single existing large detention pond into a bioretention facility, I'd say take some caution. When you overload bioretention facilities, they can turn into a real mess.
Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East - http://www.campbellcivil.com
RE: Mixing Treated Stormwater with Untreated Stormwater - calculating TMDLs
RE: Mixing Treated Stormwater with Untreated Stormwater - calculating TMDLs
Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East - http://www.campbellcivil.com