Nonmechanical Device for Stormwater Flow Control
W W ETCO, LLC
753 Grimes Bridge Road
Roswell, GA 30075
Telephone: 404-307-5731
http://www. wwe tco.com
Environmental Problem
To satisfy water quality criteria or total maximum
daily load (TMDL) allocations, regulated sources of
wet weather pollution (stormwater, combined sewer
overflows (CSOs), and sanitary sewer overflows) re-
quire cost-effective flow control and treatment tech-
nologies. Flow controls maximize wet weather flows
that can be treated without inhibiting drainage sys-
tem hydraulics or blocking the flow path. Conven-
tional flow control includes fixed weirs or more
expensive mechanical devices that can inhibit the
drainage system hydraulics or .create higher capital
and maintenance costs. Conventional approaches, in
which devices are placed in the flow path, risk up-
stream flooding or less than optimal wet weather
treatment.
SBIR Technology Solution
With support from EPA's Small Business Innovation
Research (SBIR) Program, WWETCO, LLC has de-
veloped a nonmechanical, passive-flow control de-
vice that will maximize flow attenuation and
diversion of wet weather volumes to treatment. The
WWETCO flow control can be installed at a cost
comparable to the most inexpensive fixed weir con-
trols. The device is simple, compact, and able to
handle high velocities carrying trash and abrasive
materials with virtually no maintenance. It is not af-
fected by corrosive environments. The passive flow
control device consists of a flexible bladder that
opens at the bottom in a structure containing a
static fluid that seals the bladder against a conduit
that transports dry and/or wet weather flow. The
technology can be used in a stream or water con-
veyance channel, piping network, storage basin or
structure, and as a part of a treatment system. The
WWETCO flow technology can be incorporated
into the outlet of stormwater ponds to carry a fixed
water level during dry weather or to completely
drain yet maximize their effectiveness for each
runoff event.
The flow control device uses differential hydraulic
pressure across the membrane to passively maintain
an upstream water level during changing flow con-
ditions. The flexible membrane takes on a shape to
create the head loss required to maintain the up-
stream water level and pass the excess flow to the
downstream level. The design allows the passage of
aquatic biology or other base flows during dry
weather. During runoff conditions after the up-
stream storage has been fully utilized, the flexible
membrane lifts upward as needed to pass any ex-
cess volume or debris. Because the bladder opens
from the bottom of the conduit, it is non-clogging
and provides full-bore peak flow. The technology
can be designed to seal the conduit completely or
partially, allowing passage for dry weather flow such
as sewage in a combined sewer inline storage appli-
cation or stream/groundwater base flows. The
WWETCO flow control provides diversion to treat-
ment, bypass around treatment, and/or attenuated
base flow through the flow control. It optimizes the
use of all available upstream storage before bypass-
ing any excess flow volumes not treated or stored. It
also has the ability to bypass peak flow with no sys-
tem capacity loss, eliminating any risk of upstream
flooding.
The WWETCO flow control does not require addi-
tional head or a vertical drop in the drainage system
to operate; It creates a differential head in the
drainage flow path between the maximum upstream
water level (set by the static level in the structure)
and the downstream attenuated flow depth. Flow
and treatment controls, therefore, can be placed at
any location in the collection network or drainage
system where there is existing infrastructure, avail-
able land/waterway for storage, or where residual
pollutant removals are advantageous.
Commercialization Information
Commercial applications include the optimization
of various flow controls, such as diversion, storage,
migratory tolerant stream attenuation, inline storage,
flow to treatment, creating head for treatment,
pond/stream level management, irrigation, fish lad-
ders, or other situations requiring the maintenance
of an upstream level. The preliminary commercial-
ization plan was developed from Phase I research
SBIR Success Stories

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results and combined with local, state, and federal
agency surveys of wet weather control needs. The
Phase II commercialization plan defined full-scale
hydraulic and operation performance, fabrication
and production, specific marketing strategies, infor-
mation dissemination, teaming arrangements, and
funding. Primary focus markets include the devel-
opment community and municipal governments
that are under regulatory requirements with an esti-
mated average value of $40 million per year for the
next 30 years (dependent upon geographic loca-
tion, state and federal regulatory activity, and new
development).
The flow control technology was tested in a project
that demonstrated an innovative retrofit of an exist-
ing stormwater pond serving a 300-acre commer-
cial impervious area in the Roaring Branch
watershed, a tributary to the Middle Chatta-
hoochee River in Columbus and Muscogee County,
Georgia, and in a demonstration of disinfection and
stormwater pollutant load reduction facility in Wer-
acoba Creek Watershed in Columbus, Georgia. Ad-
ditionally, the City of Columbus implemented a
stormwater treatment system to control flow and fil-
ter the runoff from its 7-acre vehicle maintenance
facility. The WWETCO flow control device was in-
stalled to provide passive wet weather treatment.
The first two projects above were tested under EPA
grant Quality Assurance Project Plan (QAPP) proto-
cols, with results showing that macro-invertebrate
species increased 100-fold and 60-fold, respec-
tively, downstream of these facilities. This improved
water quality raised the impaired stream segments
from a Class C to a Class A rating.
Company History
WWETCO specializes in the monitoring, measure-
ment, evaluation, control, and treatment of wet-
weather-related pollution. The managing principals of
this environmental products and services firm have
an average of 33 years of engineering experience, in-
cluding planning, design, construction management,
manufacturing, operations, and performance testing.
Since 1996, WWETCO has provided watershed
measurements and wet weather control technology
demonstrations for solutions to combined sewer
overflows (CSOs), stormwater, tertiary filtration,
nutrient control, optimization of biological treatment,
lagoon controls and filtration and industrial
pollution issues.
SBIR Impact
Cost-effective flow control and treatment technologies are required for
wet weather pollution, and conventional approaches are inadequate.
WWETCO has developed a non-mechanical, passive-flow control de-
vice that can be installed at costs comparable to the most inexpensive
fixed weir controls, and requires virtually no maintenance.
The device operates on a flow control-created hydraulic gradient that
allows placement of flow and treatment controls at any location along
the collection network or drainage system where residual pollutant
removals are advantageous.
| WWETCO s flow control device provides
passive wet weather treatment for the City
of Columbus, Georgia's stormwater treat-
ment system.
SBIR Success Stories

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