The Acacia Park Retention
Treatment Basin (RTB) was constructed as part of an $82
million national demonstration project. The demonstration
project is a three-phase project aimed at eliminating combined
sewage overflows (CSO) in the Rouge River watershed.
The Acacia Park RTB was constructed under the second phase
of the project, which implemented CSO controls. Phase
I included monitoring and optimizing existing combined sewer
systems and planning for CSO controls. Phase III
evaluates the results of Phase II CSO controls and initiates
further controls (if necessary) to meet water quality standards.
The Acacia Park RTB
services an 816-acre watershed, treating approximately 150
million gallons of CSO annually, of which 50 million gallons
are discharged to the Rouge River. The RTB has a
capacity of 4.0 million gallons and is 206' x 140' x 20'.
The facility is designed to provide 30 minutes detention
of the 1-year, 1-hour storm (1.0”).
The RTB receives
gravity flow from a 10' combined sewer. Two separate
cells are sequentially filled, as the facility provides
disinfection, settling and skimming. Flow exceeding the
storage capacity of the two cells is screened through 3/4”
x 3-3/4” openings and overflows via weir troughs to an effluent
channel that discharges to the Rouge River. Retained
flow in the RTB is pumped back into the Evergreen Interceptor
for treatment at the Detroit POTW. After the basin
is dewatered, a pivoting trough flushing system is used
to flush any remaining sediment from the tank bottom to
the interceptor sewer.
Construction of the
RTB was completed in February 1997. Located within
the Village of Beverly Hills Nature Preserve, construction
of the RTB included the re-establishment of a “Relic Prairie”
meadow and mitigation of 0.7 acres of wetland. The
siting of the facility allowed for several unique design
characteristics. An example of this is the control
building architecture that resembles a stable, thereby blending
with the aesthetics of the site.
The Acacia Park instrumentation
and controls are relayed into Oakland County's Supervisory
Control and Data Acquisition (SCADA) system. This
allows the County to monitor the facility from a remote
location and optimally operate the facility.