|
|
 The
City of Beverly Hills Master Plan of Drainage The City of
Beverly Hills, California, is characterized by premium commercial
and residential developments in which flood-associated damages
could easily total into the millions of dollars. The City needed
a comprehensive analysis to determine the adequacy of the existing
storm drain system. The City asked Exponent to determine the
locations of drainage deficiencies, the necessary dimensions
of any facilities needed to relieve these deficiencies, the
associated costs to build or renovate the proposed facilities,
and a facility construction prioritization based on an annual
capital improvement program (CIP) budget.
|
|
Exponent developed hydrologic parameters and hydraulic characteristics
in a geographic information system (GIS) environment and imported
them into drainage software that was developed by team members.
We also developed several other decision-making modules to
evaluate the existing drainage system deficiencies and the
costs of proposed drainage improvements in order to create
an effective construction prioritization ranking. As a result
of these analyses, the master plan we presented to the city
identified and outlined approximately $11.5 million in drainage
deficiencies and prioritized the construction of proposed
relief drainage facilities into 23 annual CIP projects with
an annual budget of $500,000 each. Pinpointing the priority
drainage projects will allow the city to relieve all but the
very lowest-risk drainage deficiencies in the first 10-12
years of CIP projects.
|
|
 Ventura
Keys and Arundell Barranca Watershed Project The Ventura
Keys is a residential waterfront development consisting of
three main channels, a stub channel, and a connecting channel
to Ventura Harbor, California. Flow patterns in the keys and
the harbor were severely affected by adverse sediment deposition
resulting from reconfiguration of the Arundell Barranca Channel
outlet structure. Homeowners claimed that this reconfiguration
led to shoaling in the channels—making the waterways
unnavigable—and to increased levels of bacteria in the
water, effectively prohibiting both human contact with water
and the recreational use of two private beaches in the Keys.
Exponent was retained by the City of San Buenaventura to
perform an investigation and feasibility study to improve
circulation in the Ventura Keys and Ventura Harbor. Our investigations
included a review of the physical model and of the underlying
conditions that resulted in the reconfiguration of the Arundell
Barranca Channel. Our team members created 2- and 3-dimensional
models that simulated the effect of a proposed channel reconfiguration,
the effect of tides on circulation in the Keys and Ventura
Harbor, the effect of a proposed debris basin on the amount
of sediment inflow into Ventura Harbor, and the potential
of the proposed channel geometry to create a density current
that would reduce dredging costs. We studied the sources and
quantities of bacteria deposition in the Keys and analyzed
an array of scenarios to mitigate the bacteria problem. As
work continues on this project, our team of scientists and
engineers has been instrumental in enabling the City of San
Buenaventura to develop a strategy to resolve residents' concerns
and improve circulation in both the Keys and Ventura Harbor
without incurring the unrealistic expense of diverting all
flow in the Arundell Barranca Channel to the Santa Clara River.
The proposed channel extension and debris basin will also
allow for a much less expensive dredging operation.
|
 Beverly
Hills Inundation Zone Delineation for Reservoir Hypothetical
Breach Conditions All municipal water supply systems depend
on treated water storage within their distribution systems.
Treated water storage is necessary for efficient and reliable
operation of the supply system. Storage allows the city to meet
peak demands, maintain fire flow pressures, and provide an emergency
reserve supply. The City of Beverly Hills, California, retained
Exponent to perform a breach and inundation analysis to help
determine what would happen if the city's proposed 2.2-million-gallon
reinforced concrete reservoir were to fail. Exponent's structural
engineers analyzed potential failure modes and developed three
possible breach sizes. Our hydraulic engineers then analyzed
the downstream impact of each of these possible breaches, which
included the development of outflow hydrographs from each of
the potential breaches. Flows could follow any one of five potential
paths downstream or split between these five paths. Exponent
also performed more detailed hydraulic analyses of the peak
flows at specific locations downstream to better define flow
velocities, depths, and top widths. As a result of our analyses,
the City of Beverly Hills now knows the potential worst-case
scenarios of inundation in the highly unlikely event that the
proposed reservoir were to suddenly fail and has effectively
evaluated safety response alternatives. These alternatives include
construction of a containment berm around the reservoir that
would capture and control any outflow in the event of a catastrophic
breach.
|
|
City of Northglenn Water Supply System Model Growth
and development in the City of Northglenn, Colorado, are causing
increased demands for water. The City meets these demands
by drawing from a number of sources using a complex system
of conveyance, storage, and treatment facilities. To ensure
an adequate, reliable water supply now and into the future,
the city must carefully plan and manage its water resources.
The City uses a computer model to help make water resources
planning and management decisions, but their current model
does not have the flexibility to keep pace with changing needs.
Exponent and City personnel are working closely together
to develop a new model that will serve the municipality's
current and future needs. The model will be used to evaluate
the benefit in yield that could be gained from adding new
sources of supply, increasing storage, and changing operations.
The modeling approach adopted is a radical departure from
the proprietary, black box models of the past. The new model
is an ExcelÁ-based tool that combines the inherent power and
capability of Excel with a Visual Basic program. The fundamental
compatibility and interrelation of Visual Basic and Excel
provide several advantages. City staff can change and modify
the program to fit their changing needs, and the utility of
the model is enhanced by a graphical user interface that capitalizes
on the graphic orientation of Visual Basic.
|
|
top | back
|
|
