HomeMy WebLinkAbout190910 Meeting 6 Staff Report
September 10, 2019
Flood Risk Reduction Strategy Task Force
Ross Bintner, P.E., Engineering Services Manager
Martha Allen, Water Resources Intern
Flood Risk Reduction Strategy Meeting 6
The questions outlined below were posed to maintenance staff by members of the City Manager’s Flood
Risk Reduction Task Force. These questions were intended to provide a better picture of maintenance
conditions, emergency response and preparedness, and communications regarding flooding concerns in the
City of Edina. Staff has attempted to provide answers to these questions and will be meeting with the Task
Force in person for additional clarification.
1. How many areas in Edina are under "flood threat"? Where are areas of the City that you see the
most flooding concerns? PW; engineering can better answer this.
2. How many of those areas are not adjacent to a body of water - i.e., creek or lakeside? PW;
engineering can better answer this.
3. Apartment Buildings/Condos/ Retail/Office - Do we know how many have experienced water in
their parking, storage areas or lower levels? None that we are aware.
4. Ground water - I've been told ground water is higher now - just how high is high? PW; engineering
can better answer this.
5. How many areas in Edina are set aside as water retention areas? PW; engineering can better answer
this.
6. What does routine maintenance on lakes, creeks, and basins look like? Routine maintenance from our
perspective is making sure that our pipes are not clogged thereby causing upstream flooding, making sure
that the storm sewer lift stations are operating properly, repairing and constructing storm sewer catch basins
and manholes that would add to sedimentation in pipes ponds, reservoirs, etc. if not properly maintained.
We sweep the streets more than two times every year. There is some streambank stabilization that the
watershed districts complete on the creeks (9 Mile and Minnehaha). This is not something that the Public
Works Department performs.
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We have recently completed some basin excavation but this task is much more challenging from a cost and
construction perspective due to the disposal and permitting necessary to perform these tasks.
7. What percentage of the Public Works budget is spent on dealing with flooding or water issues?
What is the overall budget? Approximately 14% of the entire utility budget is used for storm sewer
maintenance. $2,399,639 out of $17,368,876. Public Works also takes care of the streets and facilities but
those expenditures are not included in these numbers.
8. Have there been any studies in Edina re: land use in urban areas (heat islands) resulting in heavier
rainfall? None that I am aware.
9. Do you see flooding in new residential development caused by underground pipes bursting? None in
the past several years.
10. How do you find out when a residential home is being threatened by flooding? Normally we get a
phone call or we notice water threatening water levels due to our creek monitoring. The MCWD has done a
better job since 2014 in notifying us and reacting to incoming weather forecasts from the National Weather
Service in Chanhassen. They use this information to increase or decrease the discharge from Grays Dam on
Lake Minnetonka. We monitor this information during periods of high water daily. What are the remedies
you bring? We monitor and make sure our lift station pumps are operating when water levels are
threatening as any other day (We do this daily). We provide sand bags to those affected by creek or storm
flooding when the water levels affect their primary structure and offer advice to residential property owners
regarding cleanup after the home is flooded. We do not place or build the sandbag wall nor do we remove
the sandbags once the threat has receded. The height of the wall determines the level of protection and the
City does not take that responsibility. We will haul the sandbags away once they have been used.
11. Do you practice and have backup for emergencies? We have an emergency operation plan for flooding
activities. Our Public Works Supervisors have been trained in the ICS (Incident Command System). We work
directly with the Emergency Manager on nearly all citywide flooding emergencies. We have emergency
generator backup power supply for our sanitary and storm sewer lift stations.
12. What services do homeowners ask for when they call with flooding / wet basement issues? Mostly
looking for the cause in the case of a sanitary sewer backup and asking for sandbags when surface water is
breaching the lowest opening in the house.
13. Are the calls more about flood prevention or about remediation? More about flood prevention since
we do not offer remediation service.
14. What flooding related services are currently available to Edina homeowners?
15. What is the average annual cost to the city for these services to homeowners? See question 7
16. Does the city do any routine monitoring (e.g., of water gauges on creeks or lakes, rainfall totals,
etc.) to help predict flooding in various parts of the city? We monitor the Minnehaha and 9 Mile Creeks
daily during high water levels.
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17. Has the city identified weather related patterns that can help predict flooding in neighborhoods /
homes prone to flooding? Every storm is different. Flooding is really variable depending on the soil moisture
content, level of the creeks, precipitation and intensity. Atlas 14 is the newest flood model. Engineering can
answer that question.
18. Are there any extra precautions taken to prevent wastewater backup when flooding is imminent in a
neighborhood? Our biggest preventative measure is to clean 1/5th of the sanitary sewer system annually
and televise 1/12th of the system annually and to complete projects to eliminate and reduce infiltration and
inflow. Nearly half on the entire sanitary sewer system (which carries wastewater) is privately maintained
and managed. The entire sewer service that leaves a home is the homeowner’s responsibility to maintain.
Connections to the sanitary sewer system from sump pumps is illegal. If we notice a connection to the
sanitary sewer from a sump pump, it will be required for the homeowner to disconnect this connection and
pipe it to the street.
The CIP is the document that identifies our eventual long term fix to neighborhood flooding concerns,