HomeMy WebLinkAbout190702 TF Staff Report
July 2, 2019
Flood Risk Reduction Strategy Task Force
Ross Bintner, P.E., Engineering Services Manager
Martha Allen, Water Resources Intern
Flood Risk Reduction Strategy Introduction
Comprehensive Water Resources Management Plan and Flood Risk Reduction Strategy
In September of 2018, City Council adopted the 2018 Comprehensive Water Resources Management Plan
(CWRMP). Within this document, a plan for creating a Flood Risk Reduction Strategy (FFRS) is outlined.
The CWRMP identified and characterized flooding problems throughout the city and laid out an incremental
approach to flood protection over a generational time frame. The plan involved a suite of tools and actions
to modify flood risk, modify susceptibility to flood risk, and/or reduce impacts of flooding with
implementation activities including new capital infrastructure investments, programmatic approaches (such as
development /redevelopment permit review), and regular operation and maintenance of stormwater
systems.
The Flood Risk Reduction Strategy will modify the CWRMP and could consider a wide range of policy and
technical approaches such as; increased service levels, new technology, new infrastructure improvements,
new programs and ways of doing business, or private improvements to address flooding.
In order to fully explore these options within a local context, the Morningside neighborhood was selected as
the focal geography that will frame the creation of the FRRS. The task force and staff can investigate various
policies, technologies and infrastructure and consider their cost, effect and fit with community values.
The Flooding Problem Defined:
Flooding has historically been considered a technical problem, requiring a technical solution. The reality is
that land ownership, space, legislation, and hydrology are interwoven with values about problem ownership,
water stewardship, service tradeoffs, and transferring risk. What was once considered purely a technical
problem may be more of a mix of a technical, scientific, political, and social one. This type of problem
requires a different set of strategies, skill sets, and tools.
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Timothy M. Gieseke. Shared Governance for Sustainable Working Landscapes
The Flooding Problem - Morningside Neighborhood Context:
Weber Pond is a constructed stormwater pond built in the late 1960s. At the time of construction, the
pond was sized to accommodate a 2-percent-annnual chance (50-year) storm event. Currently, a 1-percent-
annual chance (100-year) storm event is standard practice.
An increasing impervious trend in the Morningside neighborhood also contributes to increased flood risk.
Nearly one million square feet of impervious surfaces (structures, driveways, patios, swimming pool decks,
etc.) have been added since 1950. This equates to about 14% of the total size of occupied parcels in the
Morningside neighborhood (2019, City of Edina staff).
Service level expectations from the community have also increased.
Land use: “We want homes, driveways, patios, walkways, pools, trees, parks, roads and more.”
Drainage: “Drain the land, make it useable. Dry the soils so we can build homes and grow grass.”
Stormwater management: “Make the water flow away quickly in planned areas that do not erode or
back water on to my property.”
Flood management: “Protect lives and property.”
Finally, climatologists indicate that large, intense rainfall events are occurring more frequently and climate
change predictions indicate large rainfall events (such as 50-year or 100-year events) will become more
extreme in the future. With the update to the CWRMP, the most recent precipitation frequency estimates
were incorporated into the City’s flood model which showed increased flood risk throughout the City. It
should be noted that this data only brings us to current climate conditions and does not provide protection
for additional future risk caused by climate change.
Task Force Goals:
Based on Council and community feedback, the Morningside neighborhood was selected as the focal
geography for the creation on the FRRS. The task force is charged with supporting and providing
recommendations to inform the development of this strategy. This should:
Incorporate local challenges, opportunities, knowledge, and community values
Incorporate voices from throughout the City of Edina. While the Morningside neighborhood has
been identified as a focal geography for case study, strategies and outcomes ought to be scalable
city-wide.
Identify action steps for building community capacity to address flood risk and resiliency in Edina.
Recommendations made by the FRRS Task Force will be considered for adoption by the City Council and
incorporated as an amendment to the CWRMP.
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Key questions
Where do we go next? Where should we focus our effort?
What tradeoffs are we willing to make?
What does success look like?
Who do we involve and how?