TDS Removal in Stormwater Ponds

[RedBauer]

I'm in the process of designing/researching the removal of TDS from a stormwater pond at a mining facility. The facility that I'm working on is pumping mine water to a stormwater pond. TSS settles in the forebay, however, TDS (currently a stained, greenish tint in the water) is present in the forebay, the pond, and at the discharge. Google search, stormwater handbooks, referencing other facilities indicates there isn't much information available regarding the removal of TDS. From what I've found, it appears my options may be: 1. Flocculation/chemical additive. 2. Subsurface discharge. 3. Larger pond to promote percolation/evaporation.

Does anyone have any input or dealt with TDS?

 

[SMIAH]

First, you may want to gather more data about what kind (size, nature) of TDH you'll have to remove.
This could lead you to use different options as a sediment pond (using law stokes and flow rate and some lengh to width ratio), flocculation (ouch!), infiltration (if possible), etc.

 

[beej67]

Polyacrylamide works great on suspended sediment. Try hanging a floc log in the discharge between the forebay and the main pond and see if it does the trick. It might not take much to get it to fall out.

I saw a presentation from a guy who was using PAM on a lake down in Florida, and it worked too well. After a week the lake was so crystal clear everyone could see the old tires and whatnot on the bottom, so they had to dial it back a lot. I think they were injecting it. I've done the "hang a floc log at the inlet" trick in sediment ponds in GA before and it works great. Not particularly expensive either, particularly for a mining operation.





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

http://www.campbellcivil.com

 

[SMIAH]

Liquid polyacrylamide (concentrates) require predilution. To do so, you'll need mixing & storage equipment. Then, once diluted, you can't store it for a long period of time.

With some room, you could be able to remove most TDS with a sediment pond. You have to know what you're dealing with.

Water sample ?

 

[murdock]

not sure what the cost comparison is to chemical flocculant, but there are several vendors out there selling concrete structures with removable filter media cartridges, targeted at urban stormwater sites mostly. It may be worth looking at installing one of these in-line with the sediment pond's outlet pipe. It's only effective at low flows, though, so you would need a bypass pipe to convey larger flows out of the pond.