polymers can be used to clarify stormwater, removing sediment and
reducing the total suspended solids.
It is far
better erosion control to treat the soil on the site, before it has a
chance to wash off-site. Water treatment as well, is much easier
when the soil is treated at the source. Less sediment being picked up by
stormwater means the less sediment that is moving off site, the less
turbid your stormwater is, and ultimately the more cost effective
Enhanced Stormwater Treatment Ditches are used to introduce
site-specific polymers to turbid waters in such a manner to facilitate
mixing and reaction between the polymer and the suspended particles.
The Floc Logs®
are designed for use in flowing conditions and can be used with passive
flow or active pumping systems. Mixing and reaction time with
the Floc Logs®
is extremely important to ensure the suspended sediment is fully
the flocculated particulate that forms will greatly reduce the turbidity
of the stormwater. The particulate formed can be captured by filtering
through silt fence, mulch, straw, settling in a sediment pond, or
flowing over jute fabric after the mixing reaction has been completed to
increase final water clarity.
of a Polymer Enhanced Water Treatment System:
Primary Sediment Pond / Grit
A primary sediment pond or grit
pit may be required to reduce the sediment load before treatment.
These are placed "upstream" of the mixing system to prevent sediment
from burying the mixing system with excess sediment loads. It
allows the heaviest sediment to settle out prior to treatment with the
polymer. If sediment loads of the turbid water exceed 40,000 NTU
or 4% solids, such as in active dredging operations, we suggest
including a primary sediment pond or grit pit.
Mixing / Reaction Systems
introduce site-specific Floc Logs® to turbid waters in such a
manner to facilitate mixing and reaction between the polymer and the
Open ditch design:
A ditch is created, either by
digging out the bed or building up the walls. The site-specific
are secured along the ditch, allowing the water to flow over and around
them. Checks can be placed along the ditchline to increase
turbulence and mixing with the Floc Logs®.
Water flows down the
split pipe, lined with jute to help collect the reacted sediment.
In the photo on the right, you can see where the water is flowing
out of the large red fractionation tank which was acting like a sediment
pond to collect the heaviest sediment and prevent the Floc Logs®
from being buried in sediment.
Tank Systems with Split Pipe Launder
The Water Clarification Treatment Split Pipe Launder System is designed to perform in a variety of flow conditions. The launder needs to be long enough to meet the required reaction time as seen on the site-specific lab report. Increasing the length of the launder will result in better mixing and reaction forming more flocculated particulate.
Filling the launder with sediment will reduce/ impair the reaction. The launder needs to be installed with a gradient drop that allows the turbid water to flow through it; higher sediment load will require a greater angle to allow the Floc Logs to mix effectively.
capture and filter out the reacted sediment, to discharge clarified
treated water to spread out over a delta to slow it's velocity and allow
reacted sediment to drop out of suspension. The photos below show
a series of checks built out of sandbags laid across the delta to slow
the velocity in a smaller area. Lining the dispersion field with
jute matting will provide surface area for the particulate to adhere to,
using APS Silt Stop®
on the jute matting will enhance it's "stickiness" thereby increasing
it's sediment collection capability.
are constructed of layers of geotextile fabric attached to a wooden
frame. Series of these frames are placed upright, perpendicular to
the flow of water. The water, after being treated with the Floc
passes through the baffle grid, where the treated sediment in captured
by the fabric, allowing the clarified water to pass through.
below are of waddle or check systems, lined with jute fabric. The jute fabric provides surface area for the flocculated sediment to
adhere to (as shown in the photo on the left). The treatment ditch
on the right shows the waddles, which slow the
velocity of the water and allow time for the sediment to drop out of
suspension and collect on the jute fabric.
curtains are used when working in a flowing stream. They are
constructed using open-weave geotextile fabrics attached to floats which
are hung in the water. When placed in rows one after another, they
are similar to a baffle grid, collecting reacted sediment as the water
passes through the curtains.