pared to an entirely new basin, and were able to mitigate
downstream improvements at the same time,” said St. John.
Thanks to these improvements, the city is well on its way to
solving the flooding issues in the Covington Woods region. The
off-line pond improvement project was completed in December
2016. The A- 22 Bournewood trunk line is currently under construction. The city is phasing the other projects over a number
of years and several are currently under various stages of design
and construction. The city’s holistic approach is an excellent example of how flood risks can be reduced cost-effectively while
planning for future growth and development at the same time.
“We are continuing to be good stewards for our community,” said Steubing. “The fact that the city is growing rapidly
is wonderful. But with that growth, we need to improve our
infrastructure in an efficient, cost-effective manner. The drainage projects at Covington Woods are an important component of that improvement.” WW
About the Author: Matt Manges, P.E., C.F.M., is a team leader and regional stormwater manager at Lockwood, Andrews & Newnam Inc., a national civil engineering
firm. He can be reached at MJManges@lan-inc.com.
Circle No. 229 on Reader Service Card
are controlled by a weir inlet structure. The advantage of the
offline detention facility with weir control structure is that storage can be reserved for later in the storm event in order to
capture the peak flow of the channel.
The western portion of the existing basin was excavated to
lower storage elevations while providing an overall increase
in effective storage volume. The excavated material was then
used to construct a berm along the newly established offline
basin adjacent to the channel. As part of the berm construction,
a weir was constructed in order to control flow into and out of
the detention basin. An additional low-flow outfall structure
was also constructed to fully drain the pond once the storm
peak receded. This low-flow outfall structure included a backflow device to prevent channel water surface elevations from
backfilling the detention basin ahead of the weir control structure coming into operation. In tandem with the weir control
structure, modifications to the existing control culvert structures located west of the existing detention basin were also
included. These improvements expanded the storage capacity
of the basin and mitigated potential downstream impacts from
other projects scheduled to be implemented in future phases.
“We took an existing city-owned property in a highly-developed area, expanded it for a greatly reduced cost com-
---- COMMUNITY con’t FROM page 17
ation of this secondary containment system utilized a hinged
door, with an 18-nut locking system. Tightening those 18
nuts seemed rather labor intensive for our disinfection program. We average a chlorine container change out every
two weeks in the summer, so this locking system would have
been cumbersome,” he said.
Rovanpera and his team worked with the manufacturer,
TGO Technologies, to change to a two-bolt version operated
by a jack-screw drive system. Similar to a submarine hatch, the
Chlor Tainer’s locking mechanism is based on a wheel-operated
drive chain that closes two clamshells around the door.
“That innovation resolved our problem,” he concluded,
“and led to us changing our course of action in 1998-99 to
establish a secondary containment system using a pressure-tight vessel design rather than building a bleach delivery system that would’ve cost us twice as much. Our containment
system effectively seals any potential chlorine releases in a
secure and leak-proof vessel.”
The containment system and its conveyor racks were simply positioned on a concrete pad and bolted down. Vacuum
breaker regulators are attached for fail-safe shutdown if there
is a leak downstream from the containment vessel.
The vessels are designed for not less than 40 years of ser-
vice. They enclose chlorine gas cylinders, the chlorine transfer
hose, and seismic lock-down brackets that prevent the cylin-
ders from moving during an earthquake.
A 1-ton chlorine container is pushed into the secondary
containment vessel on rollers. The chlorine transfer hose is
attached to the supply valve, pressurized, and tested for any
leaks at the hose ends. Then the door is closed and secured by
the clamshell locking mechanism.
Operators switch from the standby containment vessel by
opening the vacuum breaker valve. The switch-over is performed by a single operator and does not require the wearing
of a self-contained breathing apparatus.
To test for leaks within the containment vessel, there are
valved ports that can be opened for testing for chlorine gas. If
a leak is discovered within the containment vessel, the operator can withdraw the chlorine gas through a vacuum line that
delivers the gas into the treatment process. Thus, not only are
chlorine gas leaks contained within the containment vessel
but the gas can also be extracted and delivered via the typical
chlorine feed system. WW
About the Author: Cliff Lebowitz heads Catalytic Reporting LLC, which specializes in
third-party case history reporting for industrial equipment manufacturers. Reporting is
based on interviews of end users and is approved by them for accuracy and completeness.
Circle No. 231 on Reader Service Card
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