By running discharge water through HaloKlear DBP-2100 and GelFloc socks, RIV Construction was able to reduce the turbidity of affected water by 1,600 percent. |
The original plan entailed utilizing a pond to collect rainwater before it left the system, where gravity allowed the sediment to fall; however, the method was inefficient. "As the pond was designed to drain into a nearby creek, we had to block it off until we had no sediment in the discharge," noted Raum. "While working on a better solution, we confined it with a rubber ball in the pipe and a piece of plywood staked against the opening. This was mid-January, and the spring rains were right around the corner."
Accordingly, the construction group needed to control NTU levels of effluent stormwater leaving the water basins into a nearby creek. After using an anionic flocculant log product and jute matting with little to no effect, RIV employed a dual-polymer product by HaloKlear recommended by Keith Martin of Hanes Geo Components.
"The Chesapeake Bay is a very sensitive body of water under incredible public scrutiny," said Martin. "Although PAM products can be very effective, if you use the wrong one, the runoff will kill fish, and if the user doses the stream or basin too heavily, it can kill downstream. Having options is important for construction companies in this area."
Solution: Dual-Polymer
HaloKlear's dual-polymer product is an eco-friendly, all-natural flocculating treatment suited for handling stringent government compliance standards and returning water to the environment safely and well within regulations. The system consists of dual-polymer socks; a small weir and mixing chamber; a sediment bag; and excelsior blankets for small particulate capture escaping the sediment bag.
RIV applied HaloKlear DBP-2100 and HaloKlear GelFloc socks to two nearby stormwater basins. Influent stormwater contained 700-900 NTU, averaging 862 NTU. After the applied dual-polymer treatment, effluent discharge averaged 5.35 -- well below the 150 NTU threshold mandated by MDE.
The dual-polymer system is both anionic and cationic and uses polysaccarides (crumbled crab shells), and the anionic agent is a thickener used in foods. The product is stored in a sock and is placed inside the pipes: as the water rushes through the pipes, the polymers dissolve. Dewatering is processed by an absorbent gelling material, which in this case was provided by Hanes Geo in the form of a dewatering bag.
Moreover, water is pumped through the manifold system and into a sediment tank with a filter tank. The HaloKlear product then makes the residue flocculate, or bundle together, and water is passed through the tanks and into a silt bag, producing treated water. "The final silt bag may not have been needed, but we wanted to be sure," noted Raum.
The replacement of the anionic floc log with DPS MB kits enhanced the water quality in the existing stormwater pond and eliminated the possibility of competing chemistries when treated through the manifold optimizing floc characteristics within the sediment bag.
The manifolds pumped water through the sediment bags and transferred it across treated excelsior blankets and into the discharge basin. Following the success of HaloKlear DPS treatment in the first basin, the contractor deployed another system for future treatment in the second basin. It was determined that the results would be enhanced by increasing the sediment bag and channel footprint.