2016.05.31 Council Work Session (Tri-City)vk,4r
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TRI -CITY JOINT CITY COUNCIL WORK SHOP
(Crystal, Golden Valley, and New Hope City Councils)
AGENDA SUMMARY
MAY 31, 2016
6:30 P.M.
City of Golden Valley (Council Chambers)
7800 Golden Valley Road
Open for public observation
Light refreshments will be provided
Call to Order and Introductions (Chair Anne Norris)
2. Attendance (Tim Cruikshank) (list of attendees on back of agenda)
3. Technical Advisory Committee Update (Mark Ray)
(a) JWC Distribution System Study
(b) Joint Water Commission 36 -Inch PCCP Rehabilitation Project
(c) Emergency Water Supply
4. DeCola Ponds/Medicine Lake Road/Winnetka Avenue Flood Mitigation Project
(a) Introduction (Tim Cruikshank)
(b) Presentation (Barr Engineering)
(c) Discussion
(d) Future Council Actions
Approve Report (August 1, 2016)
Implementation Commission to Create JPA (August 1, 2016)
5. Other Business
6. Adjournment
Participants may include the following:
CRYSTAL COUNCIL:
Jim Adams, Mayor
Laura Libby, Council Member
Olga Parsons, Council Member
Elizabeth Dahl, Council Member
Jeff Kolb, Council Member
Casey Peak, Council Member
Julie Deshler, Council Member
CRYSTAL STAFF: Anne Norris, City Manager
Mark Ray, Director of Public Works/City Engineer
Randy Kloepper, Utilities Superintendent
NEW HOPE COUNCIL:
NEW HOPE STAFF:
GOLDEN VALLEY COUNCIL:
GOLDEN VALLEY STAFF:
Kathi Hemken, Mayor
John Elder, Council Member
Andy Hoffe, Council Member
Eric Lammle, Council Member
Jonathan London, Council Member
Kirk McDonald, City Manager
Bob Paschke, Director of Public Works
Chris Long, City Engineer, Stantec
Bernie Weber, Operations Manager
Dave Lemke, Utilities Supervisor
Shep Harris, Mayor
Steve Schmidgall, Council Member
Joanie Clausen, Council Member
Larry Fonnest, Council Member
Andy Snope, Council Member
Tim Cruikshank, City Manager
Marc Nevinski, Physical Development Director
Jeff Oliver, City Engineer
Sue Virnig, Finance Director
Bert Tracy, Public Works Maintenance Manager
Joe Hansen, Utilities Supervisor
R.J. Kakach, Engineer
Eric Eckman, Public Works Specialist
Sue Schwalbe, Recording Secretary
OTHERS: Barr Engineering, Inc.
Barr Engineering, Inc.
Medicine Lake Road and Winnetka Avenue Area
Long -Term Flood Mitigation Plan
Prepared for
Cities of Golden Valley, New Hope, & Crystal
Final Draft
May 31, 2016
Medicine Lake Road and Winnetka Avenue Area
Long -Term Flood Mitigation Plan
Prepared for
Cities of Golden Valley, New Hope, & Crysta
Final Draft
May 31, 2016
Medicine Lake Road and Winnetka Avenue Area
Long -Term Flood Mitigation Plan
May 31, 2016
Contents
1.0 Project Background ............................._........,..................._..............w_----------,,..,--------------_—---- ---------- ..----------- ..._-,,...1
1.1 History of ............................... _ _3
1.1.1 Medicine Lake Road Flooding...... �w.,m.,......... ............ 3
1.1.2 DeCola Ponds Flooding....._ ..... .,....,..... ,,..b....,
1.2 Past Studies..,,................................._..........................o............,......................................... ,...
1.3 Project Goals..._... ..........,------ ............. .___
5
2.0 Summary of Existing Flooding .,...,..._.......... .......,.... .....»................____ ---------------------- ....,...
2.1 Impact of Atlas 14 Precipitation Depths on Key Flood Areas P_-__.__.____________________________ ........ ....,.e,......,,.,,.7
2.2 Low Opening Survey and At -Risk Structures.. .............. .. .......... . ... . . . ................. . . . ............. ............ _10
3.0 Flood Mitigation Plan----.....................................,,,..,...,,,....,,......,......,,,.....,...,,,...__......,..,.,................,..,,,...........,.,.......15
3.1 Impact of Land Use and Policy Change (Impervious Surface Reductions).........................................15
3.2 Benefit
-Cost Analysis of Initial Flood Mitigation Alternatives....W...............
3.2.1
FEMA Benefit -Cost Analysis ....... ....,......,...n ......... ................. a...... .......... .......... .......... .� .............16
3.2.2
Damages .... ....................................... . ..................... ....v........ .............................
_17
3.2.2.1 Loss of Fu nctionR ... ....� . m .. .� . .. ,... ....
..�... �.......17
3.2.3
Project Useful Life.__... ..... ....................... ....... ,... .y ........ .Y
......... ............. —18
3.2.4
Project Costs-------------_--- ....................... ..._._....,,......... a...,......,..T.................. ................... .18
3.2.4.1 Flood Storage Mitigation Projects.—_ ................ __........ ........ .......... ............ 18
3.2.4.2 Flood Proofing .................._ .......................... ,,,. ......18
3.2.4.3 Voluntary Acquisition ----- `.... .._................................... ,...... ___
.Y ............... ___ 19
3.2.5
Benefit -Cost Analysis Results......., . .. W... ...W ...................20
3.3 Recommended Flood Mitigation Projects (Alternative 2.5) ...... ....�................ .._.....
..... .,...... .,...,....... ..22
3.3.1
Project Summary .............. ..... ......................................... ..................... .......................
..... ............ ..... _22
3.3.2
Impact on Flood Elevation and At -Risk Properties_______________„
3.3.3
Project Costs _. -A ...................... A... ... ........................ .................... .,,....... ............ -25
3.3.4
Implementation Order & Timeline....__-_-_-__-.. .......... ..........d...W
.. ......�......�� 26
4.0 Financing Strategies ---- ------
zLl Project Cost Allocations -
29
4.2 Project Financing ...... ........ ... ............ .............. -...... ........ _........ -----_-_-..~_...__........
3
4.2.1 Bonds ----- ---............ -------- -....... ------~-.-_-__-'------__-----____
........ 33
4.I1 Storm sewer improvement district ... _........... ... ... .
3�
4.2.2 Tax increment financing district ...... .-.-^---___-...... ___~~___'_._
................... 34
4.23 Tax abatement ............ ........ -...... ............ ............................. ................ .................
34
4L2/4 Stormwaterutility fees .....
........... 34
1.2-5 Ou/|dofunding sources
42.5.1 Minnesota Department ofNatural Resources ----------------------- -.........
-____35
4.2.5.2 Hennepin County ......................
4.2.53 Minnesota Board nfWater and Soil Resources (BVVSR)
36
42.5.4 Bassett Creek Watershed Management [ommission-'___
7
4.2.5.5 Other Grant Sources ... _-... .......... ................. ........ ...........................
... ........... 37
S]] Implementation Organization_
List of Tables
Table 1-1
DeCola Pends MnDNR PWI Summary .....................m.. Y r ....».,.....,.,.»
Table 2-1
Summary of ICP-S'WMM Precipitation Events.,.,...,. ..............., ..... .,...... .,................. .........
............... 7
Table 2-2
Key Flood Areas and Flood Elevation 5ummary., ....,.....,.......,..__...._ . ......................
Table 2-3
At -Risk #'roperties�,.. .. ...,..,.�.........�.....................................m,.............I.............I........-12
Table 3-1
Assumed Project Useful Life ........ ................................ ..............:..........................._,.-_--
.....18
Table 3-2
i'lanning Level Flood Proofing Casts,,. ,,. ...............,...e.®................................
.19
Table 3-3
FEMA Benefit -Cost Analysis Summary for the Flood Mitigation Alternatives.___-.-
................. 20
Table 3-4
Key Flood Areas and 100 -year Flood Elevation Summary for Alternative 2.5 .........................
23
Table 3-5
Alternative 2.5 Impact on At -Risks Structrares..............e_......----_.-----._----..,.--- ............ ..,,,,,,..,.._...,,....24
Table 3-6
Alternative 2.5 planning Level Cost ............... ............. ....... ............. _r.......... ..... 25
Table 3-7
Alternative 2.5 Implementations girder, .. W � �W..„_ .,,,,,,, ,,,
_ ......2
Table 4-1
Cost -Share Alternative' (as a Percentage and Cost) for Full Implementation of
Alternative
.5... ..... .................... ........... ....... ___ .........._d..............-----...-----..._..._......-- 31
Table 4-2 Cost -Share Alternative' (as a Percentage and Cost) to Beneficiary Properties for Full
Implementation of Alternative 2.5 ........ ................................. ........... ........................ ..,...... ..... ............. – 31
List of Figures
Figure 1-1 Project Area---.. -..._......_ ........... ... . ..... ....rt. ..... ..................... ..........
..�...
Figure 2-1 Key Food Areas and At- Ri sk Structures ................ -»..„„............ ..,.,...,...... 9
Figure 3-1 Benefit Cost Analysis Flood Mitigation Projects (Alternative 3) .................................................... 21
Figure 3-2 Recommended Flood Storage Mitigation Projects (Alternative 2.5) ...........................................27
Figure 3-3 Remaining At -Risk Structures After Implementation of Alternative 2.5 Flood Storage ......28
Figure 4-1 Beneficiary Properties for Cost -Allocation ..........W .........0 .. ........... .Y .... ..... --- ..v__._ ----- ____W___..32
List of Appendices
Appendix A Medicine Lake Road and Winnetka Avenue Long -Term Flood Mitigation Plan – Phase 1
Surnmary Memo September 5, 2014
Appendix B Medicine Lake Road and Winnetka Avenue Long -Term Flood Mitigation Plan – Strategies
for Financial Implementation Memo April 23, 2015
Appendix C Medicine Lake Road and Winnetka Avenue Long -Term Flood Mitigation Plan – Summary
of Alternative 2.5 February 16, 2016
Certifications
I hereby certify that this engineering document was prepared by me or under my direct personal
supervision and that I am a duly licensed Professional Engineer under the laws of the State of
Minnesota.
5/31/2016
Jennifer Koehler, PE Date
MN PE #: 47500
Karen Chandler, PE
MN PE #: 19252
5/31/2016
Date
Acronyms
Acronym Description
BCWMC
Bassett Creek Water Management Commission
DFA
Damage Frequency Assessment
EPA
United States Environmental Protection Agency
FDR
Flood Damage Reduction grant
FEMA
Federal Emergency Management Agency
JWC
Joint Water Commission
MLRWA
Medicine Lake Road and Winnetka Avenue
MnDNR
Minnesota Department of Natural Resources
NOAA
National Oceanic and Atmospheric Administration
PWI
public waters inventory
SSID
storm sewer improvement district
TIF
tax increment financing
USACE
U.S. Army Corps of Engineers
USDC
United States Department of Commerce
1.0 Project Background
The Medicine Lake Road and Winnetka Avenue area long-term flood mitigation plan was the outcome of
several studies and a long history of flooding in the area, including flooding at the low point on Medicine
Lake Road east of Winnetka Avenue, and downstream in the DeCola Ponds system. The Cities of Golden
Valley, New Hope, and Crystal recognized the magnitude of flooding, the potential public safety issues,
and the contribution of the watershed runoff to this problem. To begin addressing the flooding issues,
the three Cities supported the development of this long-term flood mitigation plan that outlines critical
flood mitigation projects and planning level costs that can be used to direct future efforts. Additionally,
this plan outlines the preferred cost -allocation methods, potential sources of funding, and the
organizational structure for the implementation of this plan. Hennepin County was also involved in the
flood mitigation discussions and supported the direction of this flood mitigation plan.
Figure 1-1 shows the Medicine Lake Road and Winnetka Avenue project area including the subwatersheds
and flow patterns used in the evaluation and development of the long-term flood mitigation plan (flood
mitigation plan).
Several meetings were held with staff from the three Cities to discuss the project at various points in the
flood mitigation plan development. At these meetings, the Cities' staff discussed specific items related to
the flood mitigation plan and came to consensus about the preferred approach and directed future
efforts in the flood mitigation plan development. Meetings between the staff of the three Cities were held
on the following dates:
September 12, 2014
October 7, 2014
January 23, 2015
• April 30, 2015
■ February 23, 2016
■ April 4, 2016
This report summarizes the Medicine Lake Road and Winnetka Avenue long-term flood mitigation plan as
defined through the process of this study and the input from the staff from the Cities of Golden Valley,
New Hope, and Crystal.
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1.1 History of Flooding
1.1.1 Medicine Lake Road Flooding
Several feet of flooding has been observed at the low point along Medicine Lake Road during intense
storm events, resulting in the road being temporarily impassable and posing a potential public safety
issue. The flooding at Medicine Lake Road is the result of runoff from the cities of Golden Valley, New
Hope, and Crystal. Approximately 275 acres contribute runoff to the low point along Medicine Lake Road
which during large, intense storm events, significantly contributing to the flooding on Medicine Lake Road
with the majority of the flows coming from surface overflows from the upstream areas.
Flows from the Medicine Lake Road low point reach downstream DeCola Pond B via a storm sewer pipe or
overland flow. The capacity of the current storm sewer pipe (60 -inch equivalent arch pipe) that carries
flows from the Medicine Lake Road low point south along Rhode Island Avenue to DeCola Pond B is
restrictive and cannot convey all of the flows reaching the low point. Also, high water levels in the
downstream DeCola Ponds system causes increased flood levels at the low point on Medicine Lake Road;
ultimately, the drainage from the Medicine Lake Road low point is controlled by the 15 -inch outlet from
DeCola Pond C. Surface overflows from the Medicine Lake Road low point can reach the downstream
DeCola Pond B by flowing south through existing parking lots and along Rhode Island Avenue N.
Significant flooding has occurred along Medicine Lake Road during recent intense storm events. The
flooding at the low point on Medicine Lake Road is located at the boundary of the cities of Golden Valley
and New Hope and poses a complex intercommunity water management issue resulting in serious public
safety and access issues and damages to adjacent structures.
Examples of rainfall events that have resulted in significant flooding along Medicine Lake Road include:
May 7-8, 2006 (4.0 inches of rainfall within 3.5 hours)
• June 25, 2010 (3.0 to 3.7 inches of rainfall (varying across the watershed) within 1.9 hours)
Both of these events resulted in flooding around Terra Linda Drive, Rosalyn Court, and the low point along
Medicine Lake Road, including flooding of the VFW building located at the corner of Medicine Lake Road
and Rhode Island Avenue.
More recently, rain events on June 21, 2013 (approximately 2.7 inches of rainfall) and July 28, 2015
(2.5 inches of rainfall within approximately an hour) resulted in flooding around the Medicine Lake Road
low point with ponded water observed above the curb and on adjacent turf grass.
1, 1.2 DeCola Ponds Flooding
Just downstream of the Medicine Lake Road low point are the DeCola Ponds. The DeCola Ponds system is
comprised of a series of six ponds (DeCola Ponds A through F) located in the northwestern part of the city
of Golden Valley, southeast of the intersection of Rhode Island Avenue and Medicine Lake Road (see
Figure 1-1). The DeCola Ponds system also receives flows from the cities of Crystal, New Hope and
Golden Valley. Chronic flooding has occurred historically, especially in the most downstream ponds in the
system (DeCola Ponds D, E, and F), resulting in private and public property damage. There is also one
(known) home on the southeast corner of DeCola Pond A (the most upstream pond) that has experienced
flooding issues in the past. This area is not within a Federal Emergency Management Agency (FEMA)
mapped floodplain, due to its size. Despite this, information provided by the Minnesota Department of
Natural Resources (MnDNR, 2015) shows there have been five flood insurance claims from property
owners in this area, and 11 of the residents on the DeCola Ponds have flood insurance policies.
DeCola Ponds A, B, and C were historically wetlands and are classified on the public waters inventory
(PWI) by the MnDNR. Table 1-1 summarizes the DeCola Ponds MnDNR PWI identification numbers.
Table 1-1 DeCola Ponds MnDNR PWI Summary
DeCola Pond A 27-0630P
DeCola Pond 8 and Pond C 27-0647P
The DeCola Ponds system was built in the 1960s and the ponds were originally designed for the 50 -year
storm event, which was standard at that time. However, approximately 18 of the homes were not built
according to recommendations, and as a result, the low floors/openings in many of the homes adjacent to
the ponds are below the 50 -year and 100 -year flood levels. On July 7, 1978, a large rain event resulted in
damage to about 12 of these homes on DeCola Ponds E and F. In addition to the flood damage during
the 1978 event, flood insurance claims have been made for properties on the DeCola Ponds during
several other storm events including: July 23, 1987, April 21, 2001, and June 24, 2003. In addition,
anecdotal evidence suggests there has been damage to properties that has gone unreported.
As the result of the 1978 flooding, various alternatives were evaluated (Barr Engineering Co., July 1979) to
alleviate the flooding. The alternatives evaluated included removing the stoplog weir, removing the weir
and excavating the ponds to maintain water quality treatment capacity, building a 48 -inch bypass to the
Honeywell Pond, and additional home flood proofing.
After the 1978 flooding, the City of Golden Valley and the homeowners affected by the flooding
(Wildwood Weir Association) reached a settlement. As a result of the settlement, the City and the
Association entered into an agreement in 1984 that lays out the responsibilities of the two parties with
respect to the operation of the DeCola Ponds outlet. This agreement can be found in Appendix F of the
2012 DeCola Ponds study (Barr, 2012).
In 1985, the stoplog weir outlet at DeCola Pond F was replaced by a manually -controlled adjustable gate
outlet. The residents living around the DeCola Ponds (Wildwood Weir Association) operate the gate, not
the City of Golden Valley, consistent with the 1984 agreement. When rainfall is predicted, residents lower
the gate to create additional flood storage. Under normal conditions, the DeCola Pond F gate is fully
closed, which maintains the maximum normal water level in DeCola Ponds E and F at 888 feet MSL. When
the DeCola Pond F gate is fully open, it maintains the minimum normal water level for DeCola Ponds E
and F at 886 feet MSL, 2 feet lower than when the gate is fully closed.
DeCola Ponds A, B and C are the most upstream ponds in the system. The water levels in these three
ponds typically equalize, acting essentially as one large basin. The normal water level for the three ponds
is 894 feet MSL, which is controlled by the 15 -inch outlet from DeCola Pond C. During large storm events,
DeCola Pond B receives a significant amount of flow from the upstream subwatersheds (via the storm
sewer along Rhode Island Avenue N), which is very large in comparison to the size of the pond. During
these events, flows typically back-up into DeCola Pond A for storage before discharging downstream into
DeCola Ponds B and C later in the runoff event. Additionally, DeCola Pond C receives flows from the
subwatersheds east of the railroad tracks. High water levels in DeCola Pond D are due to overflows from
DeCola Pond C during large storm events.
Although DeCola Ponds E and F are at the downstream end of the DeCola Pond system, the majority of
the flows reaching these ponds during large storm events come from their direct subwatersheds rather
than the upstream ponds. This is because DeCola Ponds A, B, and C provide for extended detention of
the runoff volumes from the upstream sub watersheds, discharging slowly via the 15 -inch outlet from
DeCola Pond C. DeCola Pond E receives flows from the upstream DeCola Pond D as well as its direct
subwatershed. DeCola Pond F receives a significant amount of flow from fairly large, developed
subwatersheds to the east of the railroad.
1.2 Past Studies
In 2011 and 2012, the City of Golden Valley completed the DeCola Ponds Area Flood Mitigation Study
(2012 DeCola Ponds Study) (Barr, 2012) to address flooding at the low point on Medicine Lake Road east
of Winnetka Avenue and around the downstream DeCola Ponds. As part of the study, Barr developed an
XP-SWMM model for the project area within Golden Valley, and incorporated an existing model originally
developed for the City of New Hope for the area upstream of Medicine Lake Road. The XP-SWMM model
was used to evaluate engineering alternatives to reduce flooding at Medicine Lake Road and in the
DeCola Ponds system.
Although several of the evaluated flood mitigation alternatives were expected to reduce flooding at
Medicine Lake Road and around the DeCola Ponds, no alternative fully resolved the flooding issues (some
structures would remain at -risk of flooding even with implementation of the project). Additionally, the
most promising flood mitigation projects came with a significant cost.
1.3 Project Goals
Because of the significant capital costs of a flood mitigation project that would only partially resolve the
flooding issue, one of the 2012 DeCola Ponds Study recommendations was for the Cities of Golden Valley,
New Hope, and Crystal to develop a long-term flood mitigation plan for the project area. Based on that
recommendation, the three Cities agreed to participate in the development of a long-term flood
mitigation plan (this study). The objective of the long-term flood mitigation plan was to evaluate other
alternatives such as property acquisition, development of flood storage, reductions of impervious cover in
the DeCola Ponds watershed, flood proofing, and to perform a cost -benefit analysis to help the Cities
make informed decisions in relation to flood mitigation alternatives.
The ultimate goal of the long-term flood mitigation plan is to reduce flood risk for properties within the
project study area and address the public safety concerns related to the inundation of Medicine Lake
Road with several feet of standing water during certain flood events. Through the plan development
process and discussions with the three Cities, the specific goals identified by the Cities were to:
• Reduce flood depth at the low point on Medicine Lake Road to approximately 1.5 to 2.0 feet
during the 100 -year design storm event to accommodate emergency vehicle routes and protect
public safety.
Reduce flood elevations at Medicine Lake Road and the DeCola Ponds to minimize property
damage.
2,0 Summary of Existing Flooding
2.1 Impact of Atlas 14 Precipitation Depths on Key Flood Areas
For this study, Barr used the XP-SWMM model that was developed for the 2012 DeCola Ponds Study. For
the 2012 study, the XP-SWMM model used the rainfall amounts for the 10-, 50-, and 100 -year, 24-hour
duration events outlined in the City of Golden Valley Surface Water Management Plan (Barr, 2009), which
were based on the precipitation events included in Technical Paper 40 (TP -40) (USDC Weather Bureau,
1961), which was the design standard at that time. These events used the SCS Type II storm distribution.
However, in 2013, the National Oceanic and Atmospheric Administration (NOAA) completed an update to
the TP -40 values to reflect more current precipitation data (NOAA Atlas 14, Volume 8 (Atlas 14)). Barr
revised the XP-SWMM model to reflect the Atlas 14 precipitation depths and used the Atlas 14 nested
storm distribution.
Table 2-1 summarizes the TP -40 precipitation depths used in the 2012 DeCola Ponds Study and the
Atlas 14 precipitation depths used for the XP-SWMM model revisions.
Table 2-1 Summary of XP-SWMM Precipitation Events
10 -year, 24-hour
50 -year, 24-hour
100 -year, 24-hour
200 -year, 24 -hours
4.2
5.3
6.0
N/A
4.3
6.4
7.4
8.6
1 - The 200 -year, 24-hour storm event was used for the benefit -cost analysis (see Section 3.2)
In addition to revising the precipitation events and storm distributions, Barr made modifications to the
infiltration parameters in the pervious areas of the model subwatersheds. When Barr developed the
XP-SWMM model for the 2012 DeCola Ponds Study, the available soils data suggested that much of the
watershed had soils classified as either HSG B (moderately drained soils) or as undefined. All undefined
soils were assumed to be HSG B. However, to address anecdotal comments from City staff that the soils
in the project area are "tight" (not conducive to infiltration), Barr revised the subwatershed infiltration
parameters as part of the model updates. Infiltration parameters were not changed in subwatersheds that
had predominantly HSG B soils. However, infiltration parameters reflective of HSG C (poorly drained soils)
were selected in subwatersheds with primarily undefined soils.
Barr utilized the revised XP-SWMM model for the existing watershed conditions to evaluate the 10 -year,
50 -year, 100 -year, and 200 -year, 24-hour storm events, based on the Atlas 14 data and the revised
infiltration parameters.
Figure 2-1 shows the existing conditions 100 -year floodplain within the project area, based on the results
of the revised XP-SWMM modeling. The figure calls out each of the flood areas within the project area
and shows the 100 -year flood inundation area. Figure 2-1 also shows the at -risk properties within the
project area (see additional discussion in the following sections). Table 2-2 summarizes the estimated
flood elevations for each flood area for the Atlas 1410 -year, 50 -year, 100 -year, and 200 -year, 24-hour
storm events. Also included in Table 2-2 is the TP -40100 -year, 24-hour flood elevation, for comparison.
Table 2-2 Key Flood Areas and Flood Elevation Summary
Area Flood A 1cripplion
1 Terra Linda Low Point
2 Medicine Lake Road Low Point/Rosalyn Court
904.6
905.3
TP -40
1 1.
905.2
D
905.6
905.9
903.8
904.7
904.5
905.1
905.4
3
4
Rhode Island Ave Low Point
Dover Hill Apartments
902.6
903.7
903.4
904.1
904.4
900.8
901.6
901.3
902.6
903.6
5
DeCola Pond A
899.7
901.6
900.8
902.6
903.6
6
DeCola Pond B
899.7
901.6
900.8
902.6
903.6
7
DeCola Pond C
899.7
901.6
900.8
902.6
903.6
8
DeCola Pond D
895.1
901.6
900.8
9016
903.6
9
DeCola Pond E
893.6
895.9
895.4
896.2
896.3
10
DeCola Pond F
893.5
895.6
895.0 895.9
896.1
11
Medicine Lake Road East of Railroad
912.9
899.7
913.2
913.1 913.2
900.8 902.6
913.3
12
East of Railroad to DeCola Pond C
901.8
903.6
13
East of Railroad at Low Point on Nevada 902.8
East of Railroad at Low Point on Sandburg 901.4
902.9
902.9
903.0
903.0
14
902.0
902.0
902.3
902.6
15
16
East of Railroad to DeCola Pond F
Honeywell Pond3
897.5
900.5
899.5
901.4
902.1
881.9
883.6 1
882.7
884.2
884.5
1- Flood elevation based on XP-SWMM modeling utilizing the Atlas 14 precipitation depths and nested storm distribution
(including adjustments for soil type and hydraulic modifications made during the Atlas 14 modeling)
2- Flood elevation based on XP-SWMM modeling utilizing the TP -40 100 -year, 24 -hr. SCS Type II storm distribution
(including adjustments for soil type and hydraulic modifications made during the Atlas 14 modeling) - for comparison
only
3- The Honeywell Pond does not include properties at -risk of flooding but flood elevations will be considered during the
evaluation of the flood mitigation alternatives.
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2.2 Low Opening Survey and At -Risk Structures
To determine which structures are at -risk of flooding, Barr conducted a survey of the lowest openings of
the structures near the key flood areas. Barr developed a preliminary list of potentially at -risk
properties/structures to be surveyed based on: (1) review of the floodplain mapping using the revised
XP-SWMM model results for the 100 -year and 200 -year events; and (2) 2007 topography data collected
by the National Geodetic Survey and available from the U.S. Army Corps of Engineers (USACE), which was
used in the original 2012 DeCola Ponds study.
Our work scope assumed that approximately 40-45 at -risk properties would be surveyed. However, upon
review of the revised XP-SWMM model results and the floodplain mapping, Barr identified approximately
90 potential at -risk properties/structures where low opening information would be needed. Because the
number of structures requiring a survey was nearly double the original estimate, Barr utilized available
past survey data as much as possible to stay within budget. Past survey data sources included:
Survey of select structures in the Terra Linda Drive and Rosalyn Court area — this survey data was
collected as part of the Terra Linda Drive, Rosalyn Court, and Medicine Lake Road — Local Flood
Improvement Project Study (Bonestroo, 2006) completed for the City of New Hope.
Survey of low opening of 7500 Winnetka Heights Drive provided by the resident in 2011.
Survey of structures on DeCola Ponds E and F collected in 1978 by Barr Engineering (Barr
Engineering Co., 1979).
Barr conducted the lowest opening surveys of potentially at -risk structures on May 13, 2014, May 15,
2014, May 21, 2014, and May 22, 2014. The lowest openings of the main structures at 48 addresses were
surveyed during this period. In addition to collecting the lowest opening data, the survey crew also
described the lowest opening, made note of the approximate depth to the lowest floor (based on the
location of the lowest opening) and the type of structure. Additionally, the survey crew photographed
each of the structures and the surveyed lowest openings.
The low opening survey utilized benchmarks from the City of Golden Valley's recent benchmark
reestablishment project, and three (3) of the structures surveyed in 1978 were resurveyed as part of the
2014 survey effort to verify the 1978 elevations. Based on the resultant similar survey elevations, the City
of Golden Valley staff indicated they were comfortable with the use of the 1978 surveys around DeCola
Ponds E and F for this flood mitigation study.
Table 2-3 summarizes the at -risk structures within the project area, based on the results of the XP-SWMM
modeling and the surveys of the low openings. At -risk structures are defined as those with low opening
elevations on the main structure that are located lower than the estimated 100 -year flood elevations for
the adjacent flood areas. It should be noted however, that structures identified as not at -risk (low
opening above the 100 -year flood elevation) may not provide the 2 feet of freeboard required by city
policy for new construction/redevelopment. Based on the results of the XP-SWMM modeling and the
lowest opening surveys, there are currently 39 structures at -risk of flooding in the project area during the
10
100 -year storm event (see Figure 2-1). Two properties historically at risk of flooding have been flood
proofed through the construction of a brick and mortar wall around the property edge or through the
closing off of the walkout basement and grading around the property and are no longer considered at -
risk of flooding.
Table 2-3 also summarizes the type of property, the associated flood area identification number, a
summary of the storm events that result in potential flooding of the structure, the lowest opening
elevation, the flood elevations for the various storm events, and the depth of flooding above the lowest
opening of the structure for each of the storm events.
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1
3.0 Flood Mitigation Plan
3.) Impact of Land Use and Policy Change (impervious Surface
Reductions)
In an effort to quantify the potential impact of land use policy changes on the reduction in flooding in the
DeCola Ponds watershed (instead of construction of expensive flood mitigation storage), Barr evaluated
the impact of impervious surface reductions within the DeCola Ponds watershed.
The first task used the existing conditions XP-SWMM model to evaluate the impact of reductions in
watershed imperviousness by 1, 2, 5, 10, and 25 percent throughout the project area on the expected
flood elevations in the key flood areas within the DeCola Ponds watershed.
The second task included determining potential reasonable reductions in imperviousness within the
DeCola Ponds watershed. The most significant opportunities to reduce imperviousness within this
watershed would be through the reduction in road widths and in parking lot area. Barr evaluated
opportunities to reduce street widths using the current road width guidance from the Cities of Golden
Valley, New Hope, and Crystal and comparing with actual road widths within the project area using GIS
software. However, the measured widths of the existing roads are already 3 to 6 feet narrower than
outlined in the Cities' current guidance, limiting opportunity to further narrow these streets. Additionally,
the pavement management plans as provided by the Cities indicate that only a few road reconstruction
projects are expected within the DeCola Ponds watershed in the next 20 years.
Regarding reducing the amount of imperious surface in parking lots, Barr considered the United States
Environmental Protection Agency (EPA) guidance related to green parking (EPA, 2014), which summarizes
the typical design criteria for parking stalls for a given land use along with the actual parking demand
(national average). Barr compared the actual parking demands (summarized in the green parking
guidance) with the Cities' parking requirement information. Barr determined there may be the
opportunity to reduce the number of parking stalls by up to 20-25 percent in commercial and industrial
areas, which translates to an overall reduction in the parking lot imperious area by approximately
10 percent.
Based on the analysis related to street widths and parking lot area, Barr estimated that a reasonable
reduction in the project area total imperiousness ranges from 0.5 to 6 percent. The XP-SWMM modeling
of different reductions in imperiousness in the DeCola Ponds watershed showed that imperious
reductions in this range will have minimal impact on the flood elevations, with a typical reduction in the
flood levels of less than 0.1 feet for the 100 -year storm event. Assuming a reasonable five (5) percent
reduction in imperiousness, no at -risk structures would be removed from the 100 -year floodplain. A
more significant reduction in imperiousness (e.g., 25 percent reduction) also would not result in the
removal of any properties from the floodplain.
The overall impact of land use changes and reductions in the DeCola Ponds watershed imperiousness on
flood elevations is less than originally expected. To alleviate flooding in the DeCola Ponds watershed, the
':3
flood mitigation plan needs to focus on the incorporation of additional flood storage throughout the
watershed to reduce flood elevations and the number of at -risk structures.
Additional details regarding the evaluation of changes to land use policy and imperviousness are
summarized in the Medicine Lake Road and Winnetka Avenue Long -Term Flood Mitigation Plan — Phase 1
Summary Memo (dated September 5, 2014) included as Appendix A to this report.
3.2 Benefit -Cost Analysis of Initial Flood Mitigation Alternatives
Based on discussions with the staff from the Cities of Golden Valley, New Hope, and Crystal, three flood
mitigation alternatives were initially evaluated to evaluate the impact on flood damage reductions, using
the XP-SWMM model for the 2-, 10-, 100-, and 200 -year design storm events. Additionally, Barr
performed a benefit -cost analysis to help the Cities select the most preferred flood mitigation alternative
to pursue.
The three flood mitigation alternatives evaluated in the benefit -cost analysis included:
Alternative 1: Existing Conditions
This alternative is the same as existing conditions (Do Nothing scenario with no flood
proofing, voluntary acquisition, or flood mitigation projects).
• Alternative 2: Flood Proofing and Voluntary Acquisition of At -Risk Structures
Based on the estimated depth of flooding and assumptions described later, this alternative
includes flood proofing of 19 structures and acquisition of 20 structures.
* Alternative 3: Flood Mitigation Projects
This alternative focuses on the construction of 14 flood storage mitigation projects within the
project area (see Figure 3-1). This evaluation included conceptual evaluation of all projects
and locations identified by the Cities' staff, with the goal of reducing the flood depth at the
low point on Medicine Lake Road to approximately 1.5 feet (18 inches) to 2.0 feet, maximizing
reductions in the 100 -year flood elevations at all key flood locations, and flood proofing
and/or voluntary acquisition of any remaining at -risk properties.
3.2.1 FEMA Benefit -Cost Analysis
Barr utilized the Federal Emergency Management Agency (FEMA) benefit -cost analysis protocol and
software (BCA Tool 5.0) to evaluate the benefit -cost of each of the initial flood mitigation alternatives
outlined above. The FEMA software ultimately determines a benefit -cost ratio that can be used by project
developers, planners, and reviewers to make it easier to determine the most cost-effective approach to
selecting projects addressing a range of natural disasters. Typically, the software is used to evaluate
individual projects for FEMA funding, with funding going to projects with a benefit -cost ratio greater than
1.0. However, FEMA usually prefers acquisition, which eliminates all flood risk.
16
For the evaluation of the proposed flood mitigation alternatives outlined above, Barr utilized the Damage -
Frequency Assessment (DFA) module to evaluate the flood mitigation alternatives. The module requires
the following information to use the software and determine the benefit -cost ratio:
• Mitigation type (acquisition, elevation, relocation, flood proofing, and drainage improvements).
ALL anticipated project costs (e.g., easements, permitting, engineering and design, construction,
and maintenance).
+ Project useful life.
■ Loss of function (e.g., roads service, utility service) BEFORE and AFTER mitigation.
• Damages BEFORE and AFTER mitigation.
Based on the inputs to the software, the FEMA benefit -cost software annualizes the expected benefits and
costs to determine the benefit -cost ratio. The benefit of the project is the difference in the expected
damages before a project and the expected damages after a project. The cost of a project is the total cost
of a proposed mitigation project.
3.2.2 Damages
To perform the benefit -cost analysis, the flood damages before and after project mitigation were
quantified for each of the various storm events. For single-family residential properties, Barr determined
flood damages based on depth -damage relationships for residential structures developed by the USACE
(USACE, 2003). With the exception of one home, all of the single-family residential properties at -risk of
flooding have walk -out basements. For these homes, Barr applied the depth -damage relationship
developed for homes that are "Two or more stories, no basement." For the remaining at -risk single-family
residential home, Barr applied the depth -damage relationship for "One story, with basement."
To determine flood damages for multi -family residential, commercial, and industrial properties, Barr staff
and a real estate consultant (Dan Wilson) conducted in-person interviews with the property owner and/or
property tenant following the USACE commercial and industrial flood damage survey primary survey form.
3.2.2.1 Loss of Function
Loss of function is part of the damages and includes loss of road service, utility service, etc. during a
flooding event. In the case of the Medicine Lake Road flood mitigation alternatives, the primary loss of
function is the flooding at the low point on Medicine Lake Road, which is impassible at times. The
frequency and duration of loss of function could be estimated based on the XP-SWMM modeling results
along with daily average traffic counts available for Medicine Lake Road (available through Google Earth
Pro, as directed by FEMA guidance and derived from Minnesota Department of Transportation, Hennepin
County and city data) to quantify damages associated with the loss of function of Medicine Lake Road as
outlined in the BCA guidance (FEMA, 2009; FEMA, 2011).
3.2.3 Project Useful life
The project useful life is a way of quantifying the lifespan of any given alternative based on available
guidance. Table 3-1 summarizes the assumed project useful life of the mitigation project types proposed
as part of this study.
Table 3-1 Assumed Project Useful Life
Flood Proofing
30 years
FEMA BCA Guidance (2011)
Acquisition I 100 years j FEMA BCA Guidance (2011)
Flood Mitigation Projects 80 years National Cooperative Highway
(Constructed Detention) I Research Program Report 792 (2014)
3.2.4 Project Costs
3.2.4.1 Flood Storage Mitigation Projects
Planning level cost estimates were developed for the various flood storage mitigation projects based on
the conceptual design of each project. Although the point estimate of cost was used for the benefit -cost
analysis, there is cost uncertainty and risk associated with this concept -level cost estimate. The costs
reported for flood mitigation projects include contingencies (25 percent), engineering and design
(30 percent), construction management (10 percent), and estimated land acquisition/easement costs (if
applicable). The costs do not include any wetland mitigation costs and assume that the excavated soils are
not contaminated. The range of probable costs presented reflects the level of uncertainty, unknowns, and
risk due to the concept nature of the individual project designs. Barr used industry resources for cost
estimating (ASTM E 2516-11 Standard Classification for Cost Estimate Classification System) to provide
guidance on cost uncertainty. Based on the current level of design (planning level estimate), the cost
range is expected to vary by -20 percent to +40 percent from the planning level point opinion of cost.
Additionally, since this is a long term flood mitigation plan, the planning level costs may need to be
adjusted for inflation.
3.2.4.2 Flood Proofing
For planning purposes, Barr assumed that any structure with a depth of flooding between 0 and 3 feet
during the 100 -year design storm event would be targeted for flood proofing measures. The planning
level costs for flood proofing of structures were based on depth of flooding, as summarized in Table 3-2.
18
Table 3-2 Planning Level Flood Proofing Costs
�? $15,000
1 $30,000
$90,000
$180,000
Although the point estimates were used for the benefit -cost analysis, the final flood proofing costs for the
flood mitigation plan were buffered by the same -20 percent to +40 percent that was applied to the flood
mitigation project costs, to reflect uncertainty in the planning level flood proofing costs.
3.2.4.3 Voluntary Acquisition
For planning purposes, Ban- estimated that any structure with a depth of flooding greater than 3 feet
during the 100 -year design storm event would be targeted for potential acquisition.
To estimate the cost of acquisition of at -risk properties for the cost -benefit analysis, Barr evaluated
acquisition costs, estimated property removal/demolition costs, and estimated relocation costs. Barr
determined the acquisition and removal costs for single-family residential properties using the current
Hennepin County taxable market values (from 2014 Hennepin County parcel data) and multiplying by a
factor of 1.5. This factor was provided by the City of Golden Valley based on recent property acquisition
and demolition costs. A real estate appraiser subconsultant (Dan Wilson) estimated the acquisition costs
for the at -risk multi -family residential, commercial, and industrial properties. These estimates were based
on in-person interviews, the current Hennepin County taxable market value, and other sources to establish
market values. Removal costs were assumed to be equivalent to 20 percent of the acquisition costs,
based on the guidance provided by the City of Golden Valley.
Although Barr originally included relocation costs in the cost estimates for each at -risk property and
included the costs used in the benefit -cost analysis, Barr removed relocation costs from the final
acquisition costs. These relocation costs were removed based on feedback from City staff at the April 30,
2015 meeting where City staff noted their assumption that any acquisitions would be voluntary.
Additionally, to account for potential increases in market values for voluntary acquisition, the estimates
were also buffered by the same -20 percent to +40 percent that was applied to the flood mitigation
project costs.
19
{
3.2.5 Benefit -Cost Analysis Results
Table 3-3 is a summary of the FEMA benefit -cost analysis for the three initial flood mitigation alternatives
for the Medicine Lake Road and Winnetka Avenue project area.
Table 3-3 FEMA Benefit -Cost Analysis Summary for the Flood Mitigation Alternatives
Alternative 1- Existing Conditions (Do Nothing) $0 $0 0.0
Alternative 2 - Flood Proofing and Acquisition Only $6,800,000 $12,300,000 0.6 G
1
Alternative 3 - Flood Mitigation Projects $6,300,000 $27,500,000 0.2
IN
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3.3 Recommended Flood Mitigation Projects (Alternative 2.5)
At the January 23, 2015 meeting where Barr presented the initial flood mitigation projects and the results
of the FEMA benefit -cost analysis, the City staff from the Cities of Golden Valley, New Hope, and Crystal
acknowledged that the most likely alternative would be some combination of Alternatives 2 and 3
(outlined above). This resulted in the evaluation of Alternative 2.5, which includes a combination of flood
mitigation projects along with voluntary acquisition and flood proofing for any of the remaining at -risk
structures. The Alternative 2.5 projects are expected to have the most significant impact on flood
elevation reduction and are primarily located on publicly owned land; however, there are several projects
that are located on private property and will require the purchase of a parcel or an easement. Appendix C
includes the memo summarizing the complete evaluation of Alternative 2.5 (dated 2/16/2016).
3.3.1 Project Summary
For Alternative 2.5, Barr evaluated eight (8) of the 14 flood storage mitigation projects from Alternative 3
using the XP-SWMM model of the project area. Figure 3-2 shows the location of the recommended flood
storage mitigation projects. The following paragraphs briefly describe each of the recommended flood
mitigation projects:
Yunker Paric Flood mitigation in Yunker Park in the City of Crystal will include development of
approximately 4.7 additional acre-feet of flood storage and diversion of storm sewer to the flood
storage site. City staff indicated that land in this park is low and often wet under existing
conditions. There may also be an opportunity to incorporate water quality treatment volume
along with the flood storage volume and create wetland habitat in this area.
Rosalyn Court: Flood mitigation at Rosalyn Court in the City of New Hope will include
development of approximately 3.3 acre-feet of flood storage on the parcel adjacent to the low
point on Medicine Lake Road. This parcel has the most at -risk structure in the Rosalyn Court
complex (2740 Rosalyn Court) and will require the purchase of the parcel for the development of
the flood storage.
Liberty Crossing: Approximately 7.8 -acre-feet of flood storage will be developed at the Liberty
Crossing redevelopment site in the City of Golden Valley. This area will provide flood mitigation
storage and convey flows from the low point on Medicine Lake Road to the expanded storage at
Pennsylvania Woods and around DeCola Ponds B and C (once constructed). The City of Golden
Valley is working with the Liberty Crossing developer on the final design and construction of the
flood mitigation project and has established a TIF district to finance the project.
• Pennsylvania Woods/DeCola Pond B and Pond C: This set of projects is intended to be
constructed together and are located in the City of Golden Valley. However, the Pennsylvania
Woods portion of this project will require acquisition of easements from the Dover Hill
Apartments property owner, while the DeCola Ponds B and C portion of the project is located on
City -owned property. The combined project will include development of approximately
24.5 acre-feet of flood storage on the wooded portion of Pennsylvania Woods and DeCola
22
Ponds B and C. Additionally, the overflow from DeCola Pond C to DeCola Pond D will be raised to
elevation 901.2 feet MSL (NGVD 1929). In addition to the development of the flood storage in
this area, there is also the opportunity to improve the habitat and ecological function while
preserving the existing recreational uses.
Isaacson Industrial Parcel/Isaacson Park: This set of projects is intended to be constructed
together and are located in the City of Golden Valley. However, the Isaacson Industrial parcel
portions of this project will require the acquisition of the property at 7145 Sandburg Road while
the Isaacson Park project is located on City -owned property. These projects will include
development of approximately 19.8 acre-feet of flood storage on an industrial parcel east of the
railroad and 0.7 acre-feet of storage at the south end of Isaacson Park. This combined project will
also include diversion of the majority of flows away from DeCola Pond F, along the east side of
the railroad, which will require coordination with the railroad. Additionally, there may be the
opportunity to incorporate water quality treatment volume along with the flood storage volume.
+ SEA School: This project will include development of approximately 8.3 acre-feet of flood storage
on the publicly owned area north of the SEA school in the City of Golden Valley. In addition to the
development of the flood storage in this area, there is also the opportunity to incorporate water
quality treatment, develop habitat, and provide educational opportunities for the SEA school.
3.3.2 Impact on Flood Elevation and At -Risk Properties
Table 3-4 summarizes the existing conditions peak flood elevations for the Atlas 14 100 -year design event
at key locations in the DeCola Ponds watershed and the expected peak flood elevation upon
implementation of the Alternative 2.5 projects.
Table 3-4 Key Flood Areas and 100 -year Flood Elevation Summary for Altemative 2.5
IN
e
Terra Linda Low Point
905.6
905.5
-
Medicine Lake Road Low
Point/Rosalyn Court
905.1
901.8
-3.3
=v
I Rhode Island Ave Low Point
904.1
901.8
-2.3
4 Dover Hill Apartments
902.6
901.8
48
DeCola Pond A
6 DeCola Pond B
902.6
901.8
4
902.6
901.8
4.8
7
DeCola Pond C
902.6
901.8
-0.8
8
DeCola Pond D
902.7
899.2
-3.5
9
DeCola Pond E
DeCola Pond F
896.2
895.9
894.0
•2.2
2.2
ID
893.7
IN
Key Flood
Area Key Flood Area Description
Existing Conditions
Flood Elevation (ft
Alternative 2.5 Flood
Elevation (ft MSQ
Change in .,
Elevation (ft)
Medicine Lake Road East of
22
Acquisition (for Construction of a
Flood Mitigation Project)
0
11
912.2
91220
23A
Railroad
4
16
Total Number of Structures
East of Railroad to DeCola
143
902.7
902:2
t7.5
Pond C
East of Railroad at Low
13
903.0
903.0
0.0
Point on Nevada
East of Railroad at Low
-4
902.3
902.3
0.0
Point on Sandburg
East of Railroad to DeCola
901.4
900.0
-1.4
Pond F
16
Honeywell Pond
884.2
884.2
-D.0
Table 3-5 summarizes the number of at -risk properties that remain after the implementation of
Alternative 2.5. Figure 3-3 shows the remaining at -risk properties after the implementation of
Alternative 2.5
Table 3-5 Alternative 2.5 Impact on At -Risk' Structures
Mitigation Type
At Risk, No Mitigation
Existing Conditions
39
Altenutiva 2-5
0
Voluntary Acquisition
0
22
Acquisition (for Construction of a
Flood Mitigation Project)
0
2�
Flood Proofing
0
23A
No Flood Risk
4
16
Total Number of Structures
a,
143
'At -Risk structures defined as those with low openings below the estimated 100 -year flood elevation
'Properties located in Golden Valley (2); There may be an opportunity to flood proof these structures and will be evaluated at each
location.
'Properties located in New Hope (1) and Golden Valley (1)
'Properties located in Golden Valley (23)
Under existing 100 -year flood conditions, there is approximately 5 feet of standing water at the low point
on Medicine Lake Road and there are 39 structures identified as being at -risk of flooding (the estimated
100 -year peak flood elevation is above the surveyed low opening). Again, the structures in Table 3-5
identified to not be at -risk (low opening above the 100 -year flood elevation) may not provide 2 feet of
24
freeboard as required by city policy for new construction/redevelopment. Based on the evaluation of
Alternative 2.5, the following is a summary of the general conclusions:
Implementation of the Alternative 2.5 projects will result in approximately 18 inches of standing
water at the low point in Medicine Lake Road during the 100 -year flood event, thus achieving one
of two project goals. This reduction in flooding will improve public safety and allow for
emergency vehicles to travel through this area during the 100 -year flood event.
Alternative 2.5 significantly reduces flooding at DeCola Ponds D, E, and F, reduces the number of
at -risk structures by 12, and minimizes the number of voluntary acquisitions, thus achieving the
second project goal.
3.3.3 Project Costs
Planning level costs were developed for implementation of Alternative 2.5, including the flood mitigation
project costs and the associated voluntary acquisition/demolition and flood proofing costs. Barr
developed the estimated costs based on the methodology discussed in Section 3.2 above.
Table 3-6 below summarizes the planning level cost estimate range for each component of
Alternative 2.5, which includes the most critical flood mitigation projects needed to help improve the
flooding around the low point on Medicine Lake Road and the DeCola Ponds.
Table 3-6 Alternative 2.5 Planning Level Cost Estimates
1— Voluntary acquisition and flood proofing costs are based on the full implementation of flood mitigation projects in Alternative 2.5
and the associated reduction in flood elevations.
25
WIP - JNq;;-
M.
Liberty Crossing Flood Mitigation Project
$ 3,750,000
$ 4,690,000
$ 6,570,000
DeCola Ponds B and C Expansion &
$ 3,660,000
$ 4,570,000
$ 6,400,000
Pennsylvania Woods Flood Mitigation Projects
Rosalyn Court Flood Mitigation Project
$ 1,790,000
$ 2,240,000
$ 3,130,000
Yunker Park Flood Mitigation Project
$ 860,000
$ 1,080,000
$ 1,510,000
Isaacson Park/Industrial Parcel Flood
$ 4,580,000
$ 5,730,000 $ 8,020,000
Mitigation Project
SEA School Flood Mitigation Project
$ 1,700,000
$ 2,130,000 $ 2,980,000
i
Flood Storage Mitigation Project
$16,340,000
$ 20,440,000 $ 28,610,000 �
Subtotal
$ 82Q000
Voluntary Acquisition and Demolition of At
$ 1,020,000 $ 1,430,000
Risk Structures)
Flood Proofing of At -Risk Structures'
$ 720,000
$ 900,000 I $ 1,270,000
Total Project Cost
$17,880,000
$ 22,360,000 $ 31,310,000
1— Voluntary acquisition and flood proofing costs are based on the full implementation of flood mitigation projects in Alternative 2.5
and the associated reduction in flood elevations.
25
? 3.3.4 Implementation Order & Timeline
Table 3-7 outlines the recommended order of flood mitigation project implementation for the projects
identified in Alternative 2.5. The order is based on engineering judgement and the expected impact of
the given project on reductions in flood elevation and the number of at -risk structures. However, the
actual sequencing of the flood mitigation projects is flexible and will be based on opportunities within the
DeCola Ponds watershed and availability of funding. For example, the Liberty Crossing flood mitigation
storage is already being pursued with a redevelopment project in the DeCola Ponds watershed.
Table 3-7 Alternative 2.5 Implementation Order
lBased on the current level of design, the cost range is expected to vary by -20 percent to +40 percent from the planning level point
opinion of probable cost.
2Reflects properties that need to be flood proofed (or voluntary acquisition) following implementation of flood mitigation projects in
Alternative 2.5; however, this plan does not preclude a property owner from pursuing flood proofing or voluntary acquisition at any
time during the life of this plan.
Additionally, as projects are implemented, the impact of the final project design should be evaluated
utilizing the XP-SWMM model for the project area to estimate the resulting flood elevations and
remaining numbers of at -risk properties which can be used to inform future decisions.
Implementation of the Alternative 2.5 flood mitigation projects has already started with the design and
construction of the Liberty Crossing flood mitigation storage and conveyance project as part of the
Liberty Crossing redevelopment project in Golden Valley. Additional projects identified in the flood
mitigation plan will be implemented as funding allows once the implementation commission is
established (see discussion in Section 5.0). Full implementation could take as long as 10 or 20 years (or
more) depending on the availability of funding for the various projects (see Section 4.1).
26
1
Liberty Crossing Conveyance/Storage
; Golden Valley
I $ 4,690,000
I
Expansion of Pennsylvania Woods & DeCola
Golden Valley
$ 4,570,000
l
Ponds B/C
Storage at Isaacson Park/Industrial Parcel;
Golden Valley
3
$ 5,730,000
Diversion from DeCola Pond F
+4
Storage at Rosalyn Court
New Hope
$ 2,240,000
S
Storage at SEA School
Golden Valley
$ 2,130,000
6
Expansion of Storage at Yunker Park
Crystal
$ 1,080,000
Ongoing
Voluntary Acquisition & Flood Proofing'
Golden Valley
$ 1,920,000
Total Project Cost
$22,360,000
lBased on the current level of design, the cost range is expected to vary by -20 percent to +40 percent from the planning level point
opinion of probable cost.
2Reflects properties that need to be flood proofed (or voluntary acquisition) following implementation of flood mitigation projects in
Alternative 2.5; however, this plan does not preclude a property owner from pursuing flood proofing or voluntary acquisition at any
time during the life of this plan.
Additionally, as projects are implemented, the impact of the final project design should be evaluated
utilizing the XP-SWMM model for the project area to estimate the resulting flood elevations and
remaining numbers of at -risk properties which can be used to inform future decisions.
Implementation of the Alternative 2.5 flood mitigation projects has already started with the design and
construction of the Liberty Crossing flood mitigation storage and conveyance project as part of the
Liberty Crossing redevelopment project in Golden Valley. Additional projects identified in the flood
mitigation plan will be implemented as funding allows once the implementation commission is
established (see discussion in Section 5.0). Full implementation could take as long as 10 or 20 years (or
more) depending on the availability of funding for the various projects (see Section 4.1).
26
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4.0 Financing Strategies
This section outlines the preferred cost allocation method as presented to, discussed with, and agreed to
by staff from the Cities of Golden Valley, New Hope, and Crystal. Additionally, this section summarizes
potential project financing options for the recommended flood mitigation projects. Further information in
relation to these items can be found in the memos includes in Appendices B and C.
4,1 Project Cost Allocutions
As part of the Alternative 2.5 analysis, four (4) cost allocation methods were further evaluated based on
input from staff from the three Cities (see Appendix Q. After careful consideration of the cost allocation
methods, the staff from the Cities of Golden Valley, New Hope, and Crystal, and a representative of
Hennepin County selected the cost allocation approach shown in Table 4-1 as the preferred method. The
approach is generally described below:
Half of the total project costs (50%) will be paid for through funding secured from outside sources
(described in Section 4.2.5)
A portion (27%) of the total project costs will be shared amongst the Cities based on the formula
listed in Table 4-1
Another portion (3%) of the total project costs will be paid by Hennepin County Transportation
Department based on its percentage of contributing drainage within the DeCola Ponds watershed
Another portion (15.8%) would be funded through the cities stormwater utility fees. The fee
increase could be limited to property owners within the DeCola Ponds watershed or spread over a
larger area such as an entire City.
• The remaining portion (4.2%) of the project costs would be paid by the direct beneficiaries
(existing at -risk properties — See Figure 4-1).
Ultimately, each City will decide what their funding sources are and how to best fund their share of the
total project. If any of the Cities determines that special assessments to benefitting property owners will
be used as a funding mechanism, the assessment terms should be according to that City's policies.
For the preferred cost allocation method to be successful, the new implementation commission (see
Section 5.0) must include a policy or an objective in the final plan to pursue outside funding sources.
Table 4-1 summarizes the breakdown of the preferred cost -share alternative, showing the percentage that
would be applied to the implementation projects. Table 4-2 further breaks down the cost assigned to the
beneficiary properties, including the cost per property and the estimated annual cost assuming recovery
periods of 10 years, 15 years, and 20 years for the special assessments. Barr also assumed that the cost
allocated to each property within the DeCola Ponds watershed is equal, regardless of property type or
value. As the Cities begin moving toward implementation of the flood mitigation projects, they may want
29
to consider a cost allocation method that considers property type or valuation to allocate costs to the
properties within the DeCola Ponds watershed.
Figure 4-1 shows the location of 36 remaining at -risk structures after the implementation of the
Alternative 2.5 flood mitigation storage. The 36 at -risk structures represent 69 individual properties (3 of
the 36 at -risk structures are condominium buildings in the Rosalyn Court complex, each containing 12
units). The following is the breakdown of the properties:
32 single family homes
36 condominium units (3 buildings x 12 units each)
1. bus ness
69 properties
The allocation to the beneficiaries does not include the following properties due to acquisition for project
construction: 7775 Medicine Lake Road (former VFW, to become the Liberty Crossing development), 7145
Sandburg Road, and 2740 Rosalyn Court.
30
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4.2 Project Financing
Cities finance capital improvement projects using a variety of tools, including:
bonds
storm sewer improvement district
* tax increment financing district
■ tax abatement
+ stormwater utility fees
outside funding sources
The above financing methods are described in in the following sections.
4.2.1 Bonds
Cities borrow money by issuing and selling municipal bonds, also known as general obligation bonds.
Cities have limits on the amount of debt they can take on through issuing and selling bonds. The current
"net debt" limit is 3% of the estimated market value of taxable property in the city (from 2014 Handbook
for Minnesota Cities, League of Minnesota Cities).
Other types of bonds include:
+ Revenue bonds — these bonds are tied to a specific funding stream
General obligation revenue bonds — these bonds are tied to both the "full faith and credit" of
the City and a specific funding stream
+ Bonds by purpose — general obligation bonds issued for a specific purpose — not a legal
requirement, but used to conveniently identify bonds to a specific project
Bonds by user — these are also called "private activity bonds" and are used partially or entirely for
private purposes, but are still tax exempt.
In some situations, city residents must vote in favor of a bond before City issuance of a bond, but there
are many exceptions to this requirement.
The Cities could sell bonds to help pay for the projects. The amount each City would need to fund
through bonding would depend on the amount of funds available in its stormwater fund (fund balance) —
i.e., the smaller the fund balance, the more bonding that would be required. The bonds are rated based
on the City's bond rating.
4.2.1 Storm sewer improvement district
The Cities may fund specialized city infrastructure by creating a storm sewer improvement district (SSID).
Cities must pass an ordinance to create an SSID. Once established, the City "may acquire, construct,
reconstruct, extend, maintain, and otherwise improve storm sewer systems and related systems" within
the SSID. The City "may also acquire, maintain and improve stormwater holding areas and ponds" for the
benefit of the SSID. The City pays for the improvements in the SSID by levying taxes on the property in the
district. Tax levies also pay for principal and interest on bonds.
4.2.2 Tax increment financing district
Cities may use tax increment financing (TIF) to fund more than local improvements. For example, the City
of Golden Valley established a TIF district to fund the Liberty Crossing flood storage/conveyance project,
which is scheduled for construction in 2016.
The TIF tool segregates tax dollars from a defined area for use in developing and improving the area,
which can include local improvements. The following is from the Handbook for Minnesota Cities (2014,
League of Minnesota Cities):
TIF takes advantage of the increases in tax capacity and property taxes from development or
redevelopment before the development actually occurs to pay for public development or redevelopment
costs. The difference in the tax capacity and the tax revenues the property generates after new
construction has occurred, compared with the tax capacity and tax revenues it generated before the
construction, is the captured value. The taxes paid on the captured value are called "increments." Unlike
property taxes, increments are not used to pay for the general costs of Cities, Counties, and Schools.
Instead, increments go directly to the development authority to repay public indebtedness or upfront
costs the City incurs in acquiring the property, removing existing structures, or installing public services.
4.2.3 Tax abatement
Through this financing tool, Cities can authorize the issuance of bonds, which are paid back with funds
collected by tax abatements. The tax is not actually forgiven (abated), but is paid normally, with the
amount of property tax levied by the City used to pay for the bonds. The following example is from the
Handbook for Minnesota Cities (2014, League of Minnesota Cities):
A City may "abate" all or a portion of City property tax on one or more parcels of real or personal
property, including machinery, for economic development purposes. And Cities may issue general
obligation or revenue bonds to construct public improvements. As the property owners pay the abated
taxes, rather than the local property taxes, the payments go directly to paying off the bonds.
Tax abatement bonds do not require a referendum approval and are excluded from debt limits. However,
in any year, the total amount of property taxes abated by a City may not exceed 10 percent of the net tax
capacity of the City for the taxes payable year applicable to the abatement or $200,000, whichever is
greater.
4.2.4 Stormwater utility fees
The three Cities have stormwater utilities in place that generate fees that could be used to help pay for
the identified projects. Stormwater utility fees may be based on the size of the property, the type of
property, or the quantity and quality of runoff and disposal difficulties. Each of the three Cities bases their
stormwater utility fees on the type of property.
Cities could impose a "user surcharge" for flood mitigation on top of the usual stormwater utility fee for
properties within the DeCola Ponds watershed or spread over a larger area such as an entire City. An
advantage of the user surcharge is that it would start generating the funds immediately.
4.2.5 Outside funding sources
As noted in Section 4.1, the preferred cost allocation alternative calls for a large percentage of the project
implementation costs to be paid for through outside sources of funding—e.g., grants, state funding
(legislation), and other outside funding sources. The following paragraphs outline several of the potential
funding sources to help implement the flood mitigation projects identified in this plan; however, this is
not an all-inclusive list and there may be additional funding sources not identified below.
4.2.5.1 Minnesota Department of Natural Resources
Grants for flood reduction/management projects are more limited than for water quality improvement
projects. The Minnesota Department of Natural Resources' (MnDNR) Flood Damage Reduction grant
(FDR) is the only state grant available for flood reduction projects. Under this program, the state can
provide cost -share grants to local units of government for up to 50 percent of the total cost of a project.
Cities, counties, towns, watershed districts and watershed management organizations, lake improvement
districts, soil and water conservation districts, and joint powers organizations composed of any of these
units (e.g., the new MLRWA implementation commission discussed in Section 5.0) may apply.
Currently, there are two different classes of grants available through the FDR Program:
1. Small grants—these grants are for projects with a total cost up to $300,000 (maximum state
share $150,000). The MnDNR grants these funds directly from general funds appropriated by the
Minnesota State Legislature. These are competitive, and are limited to available funds. Small
projects and studies are covered through this grant program.
2. Large grants—these grants are for projects with a total cost greater than $300,000 (state share
greater than $150,000). Large grant applications are received and prioritized by the MnDNR and
then presented to the Governor and the Legislature for consideration in a capital bonding bill. A
project will be funded based on its rank after prioritization and the amount of program funding
made available by the Legislature. (Note: every biennium, the Legislature appropriates funds for
these larger grants.) or flood mitigation/reduction projects to receive these funds, the projects
must be approved by the legislature (i.e., they must go through the legislative process).
35
The types of projects eligible for FDR grants include:
• structural acquisition in the 100 -year floodplain
levees, ring dikes, and flood walls
■ elevating existing structures
• flood warning systems
public education
• flood insurance studies
floodplain mapping
• comprehensive watershed plans
• flood storage easements
The implementation projects in this flood mitigation plan would likely require a large grant (and legislative
approval).
If a presidential declaration has been issued in Minnesota, FEMA pays for 75 percent of the cost of
structural acquisition, with the remaining 25 percent to be provided by the local governments. The FDR
program will pay half the local share, leaving the local government unit with only a 12.5 percent share.
The FDR program will also pay for half of the 35 percent nonfederal share of federal flood hazard
mitigation projects.
4.2.5.2 Hennepin County
There are other potential grant sources available through Hennepin County that can be used to offset
some of the costs related to the flood mitigation projects, including:
■ Hennepin County Emergency Management Department, which could provide grant funds for
flood damage reduction.
Hennepin County Environmental Services Department provides funding for assessing and/or
cleanup of contaminated (brownfields) sites.
• Hennepin County Natural Resources Grants are intended to help partners take advantage of
opportunities to implement large projects that improve water quality or preserve, establish or
restore natural areas.
4.2.5.3 Minnesota Board of Water and Soil Resources (BWSR)
BWSR receives appropriations from the Clean Water, Land & Legacy Amendment to pay for on -the -
ground conservation projects that provide multiple benefits for water quality and wildlife habitat, which
include appropriations from the Clean Water Fund. BWSR allocates Clean Water Fund monies through a
grant program to fund projects that protect, enhance, and restore water quality in lakes, rivers, and
streams in addition to protecting ground water and drinking water sources from degradation. Eligible
applicants for the BWSR Projects and Practices grant include soil and water conservation districts,
watershed districts, joint powers watershed management organizations, counties, cities, and joint powers
0
boards of these organizations. The grants require a 25% local match. A flood mitigation project that also
incorporates water quality treatment could be eligible for funding through this grant.
4.2.5.4 Bassett Creek Watershed Management Commission
The Bassett Creek Watershed Management Commission (BCWMC) may be an additional source of
funding for the proposed flood mitigation projects. The 2015-2025 BCWMC watershed management plan
(BCWMC, 2015) includes a policy that allows projects that address flooding concerns to be considered for
inclusion in the BCWMC's capital improvement program (see policy 110). In March 2016, the BCWMC
approved their 5 -year CIP for 2018-2022, which includes $1.3 million split over 2022 and 2023 for a
project somewhere in the DeCola Ponds watershed. Assuming the project moves forward, a feasibility
study would be required in 2020 and the BCWMC plan would need to be amended to include the project.
4.2.5.5 Other Grant Sources
There are other potential grant sources available through different organizations that can be used to
offset some of the costs related to the flood mitigation projects, including the Metropolitan Council and
the Minnesota Department of Employment and Economic Development. Like Hennepin County, both of
these agencies provide funding for assessing and/or cleanup of contaminated (brownfields) sites.
Additionally, the Metropolitan Council has a stormwater grant program that can be used for the
implementation of innovative stormwater management practices that improve water quality.
37
5.4 Implementation Organization
Assuming the Cities of Golden Valley, New Hope and Crystal agree to begin implementing the projects
recommended in this long-term flood mitigation plan, the next step is for the Cities to create a
commission to oversee the implementation of the plan. The commission members would be made up of
members of all three Cities, and it would make the following important decisions:
1. How much each City should contribute to the plan implementation—e.g., each City assesses just
once to cover their share of all of the recommended projects, or each City assesses on a per -
project basis.
2. When projects should be implemented.
3. How to payout the commission's funds for project implementation.
4. If policies or ordinances (e.g., zoning overlays) should be adopted in the DeCola Ponds
watershed.
The implementation commission would also provide information to the BCWMC to update the
watershed -wide XP-SWMM model after implementation of each project.
At their April 30, 2015 meeting, the City staff from the Cities of Golden Valley, New Hope and Crystal
discussed the following implementation commission options:
1. Anew joint commission, independent of any existing joint commission.
2. Part of the existing Joint Water Commission (JWC), as anew "charge" for the existing
commission.
3. Part of the Bassett Creek Watershed Management Commission (BCWMC), likely as a
subcommittee of the existing BCWMC.
At the April 30, 2015 meeting, the three Cities indicated their preference for a newjoint commission,
modeled after the existing JWC. The new joint commission would likely be similar in structure and
function as the existing JWC, meaning there would be three voting members, one each from Golden
Valley, New Hope and Crystal and each member would appointed by their respective City council through
a resolution.
The new MLRWA implementation commission could either be autonomous (e.g., it would have the
authority to order projects) or it could be required to bring recommendations back to the ultimate
authority (the three member Cities). If modeled after the JWC, the new MLRWA implementation
commission would be autonomous. In addition, the MLRWA implementation commission's decisions
could move forward upon either a simple majority vote or a unanimous vote. If modeled after the JWC,
the MLRWA implementation actions would require a two-thirds vote, except for actions such as capital
improvements, which require a unanimous vote. The new MLRWA implementation commission would
meet at least once per year to discuss projects to be implemented, the funding of projects, and other
business.
Because the MLRWA implementation commission would be similar to the existing JWC, the Cities of
Golden Valley, New Hope and Crystal (staff and City councils) would have a level of familiarity with the
function of the new MLRWA commission. Another advantage of forming a new MLRWA implementation
commission is that the new commission's sole charge would be implementing the MLRWA Long -Term
Flood Mitigation Plan.
The MLRWA implementation commission could establish a periodic stakeholder communication plan
centered on the implementation of the flood mitigation plan, which would include communications with
neighborhood residents, business representatives, and schools, etc. from the DeCola Ponds watershed.
Additional communications will happen in relation to specific projects. The technical advisors to the
MLRWA implementation commission (e.g., city technical staff and potentially others) will develop a
communications plan as one of the first tasks for approval by the MLRWA implementation commission.
To form a new MLRWA implementation commission, the Cities of Golden Valley, New Hope and Crystal
would need to develop and enter into a newjoint powers agreement, which would require the signatures
of the mayors of all three member Cities.
Should the three City Councils agree to the formation of the MLRWA implementation commission, some
of the first tasks would include:
• Development of a newjoint powers agreement to form the commission
Develop implementation schedule
• Develop policies and procedures
■ Develop financing strategies
Develop an outreach and communication plan with stakeholders
■ Pursue outside funding sources
Implement projects
See Appendix B (April 23, 2015 memo regarding financial implementation strategies) for more information
about implementation commission options.
39
6.0 References
American Society for Testing and Materials. 2011. ASTM E2516-11 Standard Classification for Cost Estimate
Classification System. ASTM International, West Conshohocken, PA, DOI: 10.1520/E2516-11
Barr Engineering. July 9, 1979. Correspondence to Mr. Jeff Sweet from Bahram Mozayeny. Low opening
survey of residences on DeCola Ponds E and F conducted in 1978.
Barr Engineering. 2009. City of Golden Valley Surface Water Management Plan. Prepared for the City of
Golden Valley.
Barr Engineering. 2012. DeCola Ponds Area Flood Mitigation Study. Prepared for the City of Golden
Valley.
Bassett Creek Watershed Management Commission. 2015.2015 — 2025 Watershed Management Plan.
Bonestroo (Now Stantec). 2006. Report for Terra Linda Drive, Rosalyn Court, and Medicine Lake Road —
Local Flood Improvement Project. Prepare for the City of New Hope.
Federal Emergency Management Agency. 2009. Final BCA Reference Guide. June 2009.
Federal Emergency Management Agency. 2011. Supplement to the Benefit -Cost Analysis Reference
Guide. June 2011.
Hennepin County. 2014. Hennepin County 2013 Parcel Data provided in GIS format.
League of Minnesota Cities. 2014. Handbook for Minnesota Cities (__ _r...:.a.-., : d ). Website accessed
March 1, 2015.
Minnesota Department of Natural Resources. 2015. Data on Flood Insurance Policies and Claims in the
Project Area.
Transportation Research Board. 2014. National Cooperative Highway Research Program Report 792:
Long -Term Performance and Life -Cycle Costs of Stormwater Best Management Practices.
United States Army Corps of Engineers. 2003. Economic Guidance Memorandum (EGM) 04-01, Generic
Depth -Damage Relationships for Residential Structures with Basements. October 10, 2003.
United States Army Corps of Engineers. 2014. USACE commercial and industrial flood damage survey
primary survey form. As provide by Jeffery McGrath on 5/5/2014.
United States Environmental Protection Agency. 2014. Best Management Practices: Green Parking
f� , . i ,_ __ _ ;;_ ). Website accessed August 1, 2014.
40
Appendix A
Medicine Lake Road and Winnetka Avenue Long -Term Flood
Mitigation Plan - Phase 1 Summary Memo
September 5, 2014
resourceful. inaturally. gARR
engmefi�q wid erwin_nrnento,l -_on3uis+lnF
Technical Memorandum
To: Jeff Oliver, Bob Paschke, & Tom Matheson
From: Jennifer Koehler, PE & Karen Chandler, PE
Subject: Medicine Lake Road and Winnetka Avenue Long -Term Flood Mitigation Plan — Phase
Summary
Date: September 5, 2014
Project: 23/27-1358
c: Len Kremer, Kirk McDonald, Anne Norris, Tom Burt
1.0 Background
In 2011 and 2012, the City of Golden Valley conducted the DeCola Ponds Area Flood Mitigation Study
(DeCola Ponds Study) (Barr, 2012) to address flooding at a low point on Medicine Lake Road east of
Winnetka Avenue and around the downstream DeCola Ponds. As part of the study, Barr developed an
XP-SWMM model for the project area within Golden Valley, incorporating an existing model originally
developed for the City of New Hope. The XP-SWMM model was used to evaluate engineering
alternatives to reduce flooding at Medicine Lake Road and in the DeCola Ponds system.
Although several of the evaluated flood mitigation alternatives were expected to reduce flooding at
Medicine Lake Road and around the DeCola Ponds, no alternative fully resolved the flooding issues (some
structures would remain at -risk of flooding even with implementation of the project). Additionally, the
most promising flood mitigation alternatives came with a significant cost ($6 to $7 million, not including
any land acquisition, easement acquisition, or wetland mitigation costs).
Because of the high expected capital costs of a project that would only partially resolve the flooding issue,
one of the recommendations from the DeCola Ponds study was for the Cities of Golden Valley, New Hope,
and Crystal to develop a long-term flood mitigation plan for the project area. The goal of the long-term
flood mitigation plan would be to evaluate other alternatives such as property acquisition, development
of flood storage, reductions of impervious cover in the watershed, and flood proofing and to perform a
cost -benefit analysis to help the cities make informed decisions in relation to flood mitigation.
Figure 1 shows the project area as evaluated in the DeCola Ponds study and for the development of the
Medicine Lake Road and Winnetka Avenue long-term flood mitigation plan (flood mitigation plan).
Barr Engineering Co. 4700 V\/est 77th Street, Suite 200, Minneapolis, MN 55435 952.832.2600 www.barr.com
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To: Jeff Oliver, Bob Paschke, & Tom Matheson
From: Jennifer Koehler, PE & Karen Chandler, PE
Subject: Medicine Lake Road and Winnetka Avenue Long -Term Flood Mitigation Plan - Phase 1 Summary
Date: September 5, 2014
Page:
2.0 Phase 1 Summary
This memo summarizes the completion of the first of two phases of the work for the flood mitigation plan
development. Phase 1 of the Medicine Lake Road and Winnetka Avenue flood mitigation project included
several tasks that built on the work completed for the City of Golden Valley as part of the DeCola Ponds
study. Phase 1 included an initial assessment, which gathered information on at -risk (flood prone
properties within the 100 -year floodplain) properties in the project area. Information collected in Phase 1
will be used to assess and prioritize the alternatives that will be evaluated in Phase 2 of this project.
Phase 1 included the following tasks:
0 Revisions to the existing XP-SWMM model of the watershed to reflect the Atlas -14 precipitation
depths and nested storm distributions, and estimate the associated flood elevations.
• Identification of potentially at -risk properties and survey of the low opening elevations of the
main structures.
It Estimation of the acquisition costs (including relocation and demolition) and the loss of tax
revenue of all at -risk properties.
+ Estimation of damages to at -risk properties.
■ Evaluation of impervious surface reductions in the watershed on flood elevations.
The following summarizes the conclusions from the Phase 1 work:
Based on the revised XP-SWMM modeling and the survey of the low openings, 41 properties are
at -risk of flooding during the 100 -year storm event.
9 The estimated costs to acquire, remove, and relocate all of the at -risk properties are
approximately $31.1 million.
■ For the at -risk properties, the estimated flood damages for the 100 -year event are approximately
$7.2 million. The most significant damages are expected around the low point on Medicine Lake
Road and Rosalyn Court and DeCola Ponds D, E, and F. Minor damages are expected around
DeCola Pond A and east of the railroad near DeCola Pond F.
■ Narrowing of streets and reducing the number of parking stalls in parking lots could result in an
overall reduction in imperviousness within the watershed ranging from 0.5 to 6 percent. The XP-
SWMM model predicted that reducing the imperviousness by 5 percent would reduce 100 -year
P:\Mpls\23 MM27\23271358 Med Lk Rd-Winnetka Mitig Plan\WorkFiles\Memo_Phase1\MLRWA Plan_ Phase1_Memo_09052014.docx
To: Jeff Oliver, Bob Paschke, & Tom Matheson
From: Jennifer Koehler, PE & Karen Chandler, PE
Subject: Medicine Lake Road and Winnetka Avenue Long -Term Flood Mitigation Plan - Phase 1 Summary
Date: September 5, 2014
Page: 4
flood elevations around DeCola Ponds A, B, C, and D by approximately 0.1 foot, with lesser
impacts on the flood elevations in other areas of the watershed. A 25 percent reduction in the
watershed imperviousness would not result in the removal of any properties from the 100 -year
floodplain.
The overall impact of reductions in the watershed imperviousness on flood elevations is less than
originally expected, partially due to changes made to the infiltration parameters in the XP-SWMM
model during the Phase 1 work. Because much of the pervious areas in the XP-SWMM model are
now modeled as hydrologic soil group (HSG) C, which have limited infiltration capacity, significant
runoff volumes can be generated from these areas during large, intense storm events. Although
reductions in imperviousness will have limited impact on large, intense flood events, it would have
a more significant impact on smaller, more frequent storm events and water quality.
Development of flood storage will likely need to be a major component in the alternatives
analysis to be completed in Phase 2.
The remaining sections discuss each of the Phase 1 tasks in more detail and will summarize the results of
the Phase 1 analyses.
2.1 XP-SWMM Model Revisions
For the Phase 1 analyses, Barr used the XP-SWMM model that was originally developed for the DeCola
Ponds Study completed in 2012. For the DeCola ponds study, the XP-SWMM model used the rainfall
amounts for the 10-, 50-, and 100 -year, 24-hour duration events outlined in the City of Golden Valley
Surface Water Management Plan (Barr, 2009), which were based on the precipitation events included in
Technical Paper 40 (TP -40) (USDC Weather Bureau, 1961) which was the design standard for the past 50
years. These events used the SCS Type II storm distribution. However, in 2009, the National Oceanic and
Atmospheric Administration (NOAH) began a project to update the TP -40 values to reflect more current
precipitation data. These updates, known as NOAA Atlas 14, Volume 8 (Atlas 14), were finalized in 2013.
We revised the Phase 1 XP-SWMM model to reflect the Atlas 14 precipitation depths and used the Atlas
14 nested storm distribution.
Table 1 summarizes the TP -40 precipitation depths used in the 2012 DeCola Ponds study and the Atlas 14
precipitation depths used for the Phase 1 XP-SWMM model revisions.
P:\Mpls\23 MN\27\23271358 Med Lk Rd-Winnetka Mkig Plan\WorkFiles\Memo_Phasel\MLRWA_Plan-Phasel Memo_09052014.docx
To: Jeff Oliver, Bob Paschke, & Tom Matheson
From: Jennifer Koehler, PE & Karen Chandler, PE
Subject: Medicine Lake Road and Winnetka Avenue Long -Term Flood Mitigation Plan - Phase 1 Summary
Date: September 5, 2014
Page:
Table 1 Summary of XP-SWMM Precipitation Events
Storm Event TP -40 Precipitation Depth (in) Atlas 14 Precipitation Depth (in)
10 -year, 24-hour 4.2 4.3
50 -year, 24-hour 5,3 6.4
100 -year, 24-hour 6.0 T-1
200 -year, 24-hour NIA U
In addition to revising the precipitation events and storm distributions, we made modifications to the
infiltration parameters in the pervious areas of the model subwatersheds. When we developed the XP-
SWMM model for the 2012 DeCola Ponds study, the available soils data suggested that much of the
watershed had soils either classified as HSG B (moderately drained soils) or as undefined. All undefined
soils were assumed to be HSG B. However, to address anecdotal comments from city staff about the soils
in the project area are "tight" (not conducive to infiltration), we revised the subwatershed infiltration
parameters as part of the Phase 1 model updates. Infiltration parameters were not changed in
subwatersheds that had predominantly HSG B soils. However, infiltration parameters reflective of HSG C
(poorly drained soils) were selected in subwatersheds with primarily undefined soils.
We utilized the revised XP-SWMM model for the existing watershed conditions to evaluate the 10 -year,
50 -year, 100 -year, and 200 -year, 24-hour storm events based on the Atlas 14 data and the revised
infiltration parameters.
Figure 2 shows the existing conditions 100 -year floodplain within the project area based on the results of
the revised XP-SWMM modeling. The figure calls out each of the flood areas within the project area and
includes the 100 -year flood elevation. This figure also shows the at -risk properties within the project area
(see additional discussion in the following sections). Table 2 summarizes the estimated flood elevations
for each flood area for the Atlas 14 10 -year, 50 -year, 100 -year, and 200 -year, 24-hour storm events. Also
included in Table 2 is the TP -40 100 -year, 24 -hr flood elevation, for comparison.
P:\Mpls\23 MN\27\23271358 Med Lk Rd-Winnetka Wig Plan\WorkFiles\Memo_Phasel\MLRWA Plan_Phasel_Memo_09052014.docx
To: Jeff Oliver, Bob Paschke, & Tom Matheson
From: Jennifer Koehler, PE & Karen Chandler, PE
Subject: Medicine Lake Road and Winnetka Avenue Long -Term Flood Mitigation Plan- Phase 1 Summary
Date: September 5, 2014
Page: 6
Table 2 Key Flood Areas and Flood Elevation Summary
Flood
Area
Flood Area Description
Froud Elevation %ra-rvaavv c71
I TP -40
10 -yr I 50 -yr 1 100-yr2 100 -yr
200 -yr
1
Terra Linda Low Point
Medicine Lake Road Low Point/Rosalyn Court
904.6 905.3
903.8 904.7
905.2
904.5
905.6
905.1
905.9
2
905.4
3
4
Rhode Island Ave Low Point
Dover Hill Apartments
902.6
903.7
903.4
904.1
904.4
900.8
901.6
901.3
902.6
903.6
5
Decola Pond A
899.7
901.6
900.8
902.6
903.6
6
Decola Pond B
899.7
901.6
901.6
900.8
900.8
902.6
902.6
903.6
903.6
7
Decola Pond C
899.7
8
9
Decola Pond D
Decola Pond E
895.1
901.6
90018
902,6
903.6
893.6
895.9
895.4
896.2
896.3
10
Decola Pond F
893.5
895.6
895.0
895.9
896.1
11
Medicine Lake Road East of Railroad
912.9
913.2
901.8
913,1
900.8
913.2
913.3
12
East of Railroad to Decola Pond C
899.7
902.6
903.6
13
East of Railroad at Low Point on Nevada
902.8
901.4
902,9
902.0
902.9
902.0
903.0
902.3
903.0
14
East of Railroad at Low Point on Sandburg
902.6
15
East of Railroad to Decola Pond F
Honeywell Pond
897.5
881.9
900.5
883.6
899.5
882.7
901.4
884.2
902.1
16
884.5
1- Flood elevation based on XP-SWMM modeling utilizing the Atlas 14 precipitation depths and nested storm distribution
(including adjustments for soil type and hydraulic modifications made during the Phase 1 Atlas 14 modeling)
2- Flood elevation based on XP-SWMM modeling utilizing the TP -40 100 -year, 24 -hr SCS Type Il storm distribution (including
adjustments for soil type and hydraulic modifications made during the Phase 1 Atlas 14 modeling) - for comparison only
3- The Honeywell Pond is does not include properties at -risk of flooding but will be evaluated as part of the various flood
mitigation alternatives as part of Phase 2.
P:\Mpls\23 MN\27\23271358 Med Lk Rd-Winnetka Mitig Plan\WorkFiles\Memo_Phasel\MLRWA_Plan_Phasel_Memo_09052014.docx
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To: Jeff Oliver, Bob Paschke, & Tom Matheson
From: Jennifer Koehler, PE & Karen Chandler, PE
Subject: Medicine Lake Road and Winnetka Avenue Long -Term Flood Mitigation Plan - Phase 1 Summary
Date: September 5, 2014
Page:
2.2 Survey
To determine which structures are at -risk of flooding, Barr conducted a survey of the lowest openings of
the structures near the key flood areas. We developed a preliminary list of potentially at -risk
properties/structures to be surveyed based on 1) review of the floodplain mapping using the revised XP-
SWMM model results for the 100 -year and 200 -year events, and 2) 2007 topography data collected by the
National Geodetic Survey and available from the U.S. Army Corps of Engineers (USACOE) (as was used in
the original DeCola Ponds study).
Our work scope assumed that approximately 40-45 at -risk properties would be surveyed. However, upon
review of the revised XP-SWMM model and the floodplain mapping, we identified approximately 90
properties/structures as potentially at -risk and requiring the lowest opening survey. Because the number
of structures requiring a survey was nearly double the original estimate, we utilized available past survey
data as much as possible to stay within budget. Past survey data sources included:
• Survey of select structures in the Terra Linda Drive and Rosalyn Court area - this survey data was
collected as part of the Terra Linda Drive, Rosalyn Court and Medicine Lake Road - Local Flood
Improvement Project Study (Bonestroo, 2006) completed for the City of New Hope
Survey of low opening of 7500 Winnetka Heights Drive provided by the resident in 2011
a Survey of structures on DeCola Ponds E & F collected in 1978 by Barr Engineering (Barr, 1979)
Barr conducted the lowest opening surveys of potentially at -risk structures on May 13, 2014, May 15,
2014, May 21, 2014, and May 22, 2014. The lowest openings of the main structures at 48 addresses were
surveyed during this period. In addition to collecting the lowest opening data, the survey crew also
described the lowest opening, made note of the approximate depth to the lowest floor (based on the
location of the lowest opening) and the type of structure. Additionally, the survey crew photographed of
each of the various structures along with the lowest openings that were surveyed.
The low opening survey utilized benchmarks from the City of Golden Valley's recent benchmark
reestablishment project, and three (3) of the structures surveyed in 1978 were resurveyed as part of the
recent survey effort to verify the 1978 elevations. Based similar survey elevations, the City of Golden
Valley staff indicated they were comfortable with the use of the 1978 surveys for this flood mitigation
study.
Table 3 summarizes the at -risk properties within the project area, based on the results of the XP-SWMM
modeling and the surveys of the low opening. At -risk properties were properties with low opening
elevations on the main structure that were located lower than the estimated 100 -year flood elevations for
the adjacent flood areas. Based on the results of the XP-SWMM modeling and the lowest opening
P:\Mpls\23 MN\27\23271358 Med Lk Rd-Winnetka Wig Plan\WorkFiles\Memo_Phasel\MLRWA_Plan_Phasel_Memo_09052014.docx
To: Jeff Oliver, Bob Paschke, & Tom Matheson
From: Jennifer Koehler, PE & Karen Chandler, PE
Subject: Medicine Lake Road and Winnetka Avenue Long -Term Flood Mitigation Plan - Phase 1 Summary
Date: September 5, 2014
Page: 9
surveys, there are currently 41 properties at -risk of flooding in the project area during the 100 -year storm
event (see Figure 2). Included in Table 3 are three structures identified to flood during the 200 -year
storm event. Table 3 also summarizes the type of property, the associated flood area, a summary of the
storm events that result in potential flooding of the structure, the lowest opening elevation, the flood
elevations for the various storm events, and the depth of flooding above the lowest opening of the
structure for each of the storm events.
P:\Mpis\23 MFl\27\23271358 Med Lk Rd-Winnetka Wig Plan\WorkFiles\Memo_Phasel\MLRWA_Plan_Phasel Memo_09052014.docx
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To: Jeff Oliver, Bob Poschke, & Tom Matheson
From: Jennifer Koehler, PE & Karen Chandler, PE
Subject: Medicine Lake Road and Winnetka Avenue Long -Term Flood Mitigation Plan — Phase 1 Summary
Date: September 5, 2014
Page: 13
2.3 Property Acquisitions
After identifying the properties at -risk of flooding in the 100 -year storm event, the property acquisition
costs were evaluated along with an estimate of property removal/demolition costs. Relocation costs for
at -risk properties were also estimated.
To determine the acquisition and removal costs for single-family residential properties, the acquisition
and removal costs were based on the current Hennepin County taxable market values multiplied by a
factor of 1.5. This factor was provided by the City of Golden Valley based on recent property acquisition
and demolition costs. Dan Wilson, a real estate appraiser subconsultant, determined the relocation costs
for all properties, including finding new properties, moving expenses, and other incidental costs
associated with relocation.
Wilson also estimated the acquisition and relocation costs for the at -risk multi -family residential,
commercial, and industrial properties. These estimates were based on in-person interviews, use of the
current Hennepin County taxable market value, and other sources to establish market values. Removal
costs were assumed to be 20 percent of the acquisition costs, based on the guidance provided by the City
of Golden Valley.
Table 4 summarizes the acquisition, removal, and relocation costs for all at -risk properties within the
project area by property type. Also included in the table is a summary of the estimated annual tax
revenue from the at -risk properties.
Table 4 Summary of Acquisition & Removal and Relocation Costs for At -Risk Properties
Acquisition and
Property Type Removal Cost' I Relocation Costz
Total Tax Revenue3
Single -Family Residential 1 $17,507,280 $1,329,000 h $18,836,280 1 $208,448
Multi -Family Residential I $6,624,000 $682,000 $7,306,000 $30,983
CommercialAndustrial $4,260,000 $680,000 $4,940,000 $126,747
Total $28,391,280 I $2,691,000 $31,082,280 $366,178
1 - Acquisition and removal costs for single family residential properties based on the current Hennepin County Market Value
multiplied by 1.5. Acquisition costs for multi -family residential, commercial, and industrial determined by Wilson, with removal
costs estimated to be of 20% of the acquisition cost.
2 - Relocation costs for single family -residential, multi -family residential, commercial, and industrial determined by a real estate
appraisal consultant.
3 - Tax revenue reflects the current Hennepin County tax information for at -risk properties. This information will be utilized in the
cost -benefit analysis in Phase 2 of the project.
P:\Mels\23 MN\27\23271358 Med Lk Rd-Winnetka Mitig Plan\WorkFiles\Memo_Phasel\MLRWA_Plan_Phasel_Memo_09052014.docx
To: Jeff Oliver, Bob Paschke, & Tom Matheson
From: Jennifer Koehler, PE & Karen Chandler, PE
Subject: Medicine Lake Road and Winnetka Avenue Long -Term Flood Mitigation Plan - Phase 1 Summary
Date: September 5, 2014
Page: 14
2.4 Damage Assessments
In addition to understanding the costs to acquire the at -risk properties, damages due to flooding for the
various storm events were estimated. For single-family residential properties, Barr determined flood
damages based on depth -damage relationships for residential structures developed by the USACOE
(USACOE, 2003). With the exception of one home, all of the single-family residential properties at -risk of
flooding have walk -out basements. For these homes, we applied the depth -damage relationship
developed for homes that are "Two or more stories, no basement." For the one other at -risk single-family
residential home, the depth -damage relationship for "One story, with basement" was applied.
To determine flood damages for multi -family residential, commercial, and industrial properties, Barr staff
and Dan Wilson conducted in-person interviews with the property owner and/or property tenant
following the USACOE commercial and industrial flood damage survey primary survey form.
Table 5 summarizes the frequency -damage estimates for the various flood areas within the project area.
The most significant estimated damages were found around the Medicine Lake Road low point east of
Winnetka Avenue and around DeCola Ponds D, E, and F.
P:\Mpls\23 MN\27\23271358 Med Lk Rd-Winnetka Mitig Plan\WorkFiles\Memo_Phasel\MLRWA_Plan_Phasel_Memo_09052014.docx
To: Jeff Oliver, Bob Paschke, & Tom Matheson
From: Jennifer Koehler, PE & Karen Chandler, PE
Subject: Medicine Lake Road and Winnetka Avenue Long -Term Flood Mitigation Plan- Phase 1 Summary
Date: September 5, 2014
Paae: 15
Table 5 Area Frequency Damage' Curves
Flood
Area
Flood Area Description
Damage
10 -yr
Damage Damage
50 -yr 100 -yr
Damage
200 -yr
1
2
Terra Linda Low Point
Medicine Lake Road Low Point/Rosalyn Court
$0
$0
$0
$3,027,000
$89,330
$160,000
$2,987,000
$3,027,000
3
Rhode Island Ave Low Point
Dover Hill Apartments
$0
$0
$0
$0
$0
4
$0
$0
$40,000
5
Decola Pond A
$0
$222,035
$280,394
$334,729
6
Decola Pond B
$0
$0
$0
$0
7
Decola Pond C
$0
$0
#0
$2,729,351
$0
$3,093,051
8
Decola Pond D
$0
$2,339,775
9
Decola Pond E
$1,406,189
$2,581,726
$2,721,354
$2,820,331
10
Decola Pond F
$632,678
$1,538,410
$1,565,682
$1,664,293
11
Medicine Lake Road East of Railroad
$0
$0
$0
I $0
$0
$0
12
East of Railroad to Decola Pond C
$o
$0
13
East of Railroad at Low Point on Nevada
$0
$0 $0
$0
14
East of Railroad at Low Point on Sandburg
$0
$0 $0
$0
15
East of Railroad to Decola Pond F
$0
$0 $130,000=$130,000
16 Honeywell Pond
TOTAL
'S0
$2,038,867
50
$0
$0
$7,707,674
$6,459,911
$7,146,387
1 - Damage for single-family home estimated using the USACOE Economic Guidance Memorandum (EGM) 04-01, Generic Depth-
Damaae Relationships for Residential Structures with Basements (October 2003). Damaae estimates for multi -family, commercial. and
industrial properties based on in-person interviews with the property owner and/or property tenant following the USACOE
Commercial and Industrial Flood Damage Survey Primary Survey Form
2.5 Impervious Surface Reductions
The final task in Phase 1 was to evaluate the impact of impervious surface reductions within the watershed
as a potential flood mitigation alternative. Barr first utilized the XP-SWMM model to evaluate the impact
of impervious surface reductions on the predicted flood elevations. The watershed imperviousness was
modified to reflect 1, 2, 5, 10, and 25 percent reductions in impervious coverage throughout the project
area.
Table 6 summarizes the expected change in flood elevation at each of the flood areas for the 10 -year,
50 -year, 100 -year, and 200 -year storm events with the various reductions in imperviousness.
P:\Mpls\23 MN\27\23271358 Med Lk Rd-Winnetka Wig Plan\WorkFiles\Memo_Phase1\MLRWA Plan_Phase1_Memo_09052014.docx
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To: Jeff Oliver, Bob Paschke, & Tom Matheson
From: Jennifer Koehler, PE & Karen Chandler, PE
Subject: Medicine Lake Road and Winnetka Avenue Long -Term Flood Mitigation Plan - Phase 1 Summary
Date: September 5, 2014
Page: 17
The second step was to evaluate what might be a reasonable reduction in imperviousness within this
watershed. The most significant opportunities to reduce imperviousness within this watershed would be
through the reduction in road widths and in parking lot area.
Barr evaluated opportunities to reduce street widths. The current road width guidance from the Cities of
Golden Valley, New Hope, and Crystal was compared with actual road widths within the project area using
GIS software, measuring road widths on aerial photos using the road types classifications as included in
the 2013 MnDOT streets and highways information. Review of the pavement width guidance as
compared to the actual pavement widths as measured in GIS suggests that for many of the local roads,
street widths have already been reduced to widths lower than outlined in the Cities' guidance documents.
For example, the guidance for the Cities of Golden Valley, New Hope, and Crystal suggest a 30 foot width
for local roads; however, actual measured width indicate that local roads widths within the project area are
typically within 24 to 27 feet, already 3 to 6 feet narrower that the guidance would suggest. Based on
analysis of the streets in the project area, a one (1) foot reduction in street width translates to a 3 percent
reduction in street area. An eight foot reduction in street width equals a 23 percent reduction in street
area.
Barr also reviewed the pavement management plans as provided by the Cities. The City of Golden Valley
current pavement management plan suggests that some of the roads in the western portion of the
project area will be addressed in 2019, including narrowing the width of the streets in the project area to
approximately 26 feet. However, the City of New Hope does not have any upcoming road reconstruction
projects in the project area, and all roads in the City of Crystal within the project area were reconstructed
in the 1990's and there are no plans for reconstruction within the next 20 years.
With regards to reducing the amount of impervious surface in parking lots, Barr considered the
Environmental Protection Agency (EPA) guidance related to green parking (EPA, 2014). This guidance
summarizes the typical design criteria for the number of stalls for a given land use type along with the
actual parking demand (national average). We compared the actual parking demands with the parking
requirement information from the Cities of Golden Valley, New Hope, and Crystal. For commercial areas
and shopping centers, there may be the opportunity to reduce the number of parking stalls by up to 20
percent. For industrial areas, actual average parking demand as compared to the Cities' current parking
requirements suggests that the number of parking stalls could potentially be reduced by up to 25 percent.
We estimated that the reductions in the number of parking stalls (approximately 20-25 percent) would
result in an overall reduction in the parking lot impervious area by approximately 10 percent.
To understand the impact of impervious surface reductions through narrowing of streets and reducing the
number of parking stalls on the overall imperviousness of different land use types, Barr incorporated the
expected reductions in street and parking lot area into a breakdown of the various impervious surface
P:\Mpls\23 MN\27\23271358 Med Lk Rd-Winnetka Wig Plan\WorkFiles\Memo_Phasel\MLRWA_Plan_Phasel_Memo_09052014.dou
To: Jeff Oliver, Bob Paschke, & Tom Matheson
From: Jennifer Koehler, PE & Karen Chandler, PE
Subject: Medicine Lake Road and Winnetka Avenue Long -Term Flood Mitigation Plan - Phase 1 Summary
Date: September 5, 2014
Page: 18
types different land uses (Barr, 2005; Barr, 2011). Based on the analysis related to street widths and
parking lot area, reasonable reductions in the project area total imperviousness ranges from 0.5 to 6
percent reductions.
The XP-SWMM modeling of different reductions in imperviousness in the watershed has shown that
impervious reductions in this range will have minimal impact on the flood elevations, with a typical
reduction in the flood levels of less than 0.1 feet for the 100 -year storm event. Assuming a reasonable
reduction of imperviousness by five (5) percent, the most significant change in the flood elevation would
be seen around DeCola Ponds A, B, C, and D. However, these are not the ponds with the most significant
flooding (DeCola Ponds E and F). A five (5) percent reduction in imperviousness would not remove any
at -risk structures from the 100 -year floodplain. Even a more significant reduction in imperviousness (e.g.
25 percent reduction), would not result in the removal of any properties from the floodplain.
The overall impact of reductions in the watershed imperviousness on flood elevations is less than
originally expected. This is partially due to changes made to the infiltration parameters in the XP-SWMM
model during the Phase 1 work. Because much of the pervious area in the XP-SWMM model is now
modeled as HSG C, which have limited infiltration capacity, significant runoff volumes can be generated
from these areas during large, intense storm events. Although there are small reductions in flood
elevations during large precipitation events, the impact of the reductions in imperviousness would have a
more significant impact on the smaller, more frequent storm events and improvements to water quality.
3.0 Next Steps
The final task of Phase 1 includes two meetings with staff from the Cities of Golden Valley, New Hope, and
Crystal. At the first meeting, we will summarize the results of the original DeCola Ponds study and Phase
1 of the Medicine Lake Road and Winnetka Avenue long term flood mitigation plan. The second meeting
will include the development of 2-3 flood mitigation alternatives for the project area to be further
assessed in Phase 2 of the project.
Phase 2 of the project will include the evaluation of the 2-3 flood mitigation alternatives identified at the
meeting with staff from the Cities of Golden Valley, New Hope, and Crystal. This will include completion
of a cost -benefit analysis for each of the flood mitigation alternatives to help determine the most cost-
effective solution. Additionally, Phase 2 will include the development of strategies for financial
implementation of the flood mitigation alternative.
P:\Mpls\23 MN\27\23271358 Med Lk Rd-Winnetka Mitig Plan\WorkFiles\Memo_Phase1\MLRWA Plan_ Phasel_Memo_09052014.doa
To: Jeff Oliver, Bob Paschke, & Tom Matheson
From: Jennifer Koehler, PE & Karen Chandler, PE
Subject: Medicine Lake Road and Winnetka Avenue Long -Term Flood Mitigation Plan - Phase 1 Summary
Date: September 5, 2014
Paae: 19
4.0 References
Barr. July 9, 1979. Correspondence to Mr. Jeff Sweet from Bahram Mozayeny. Low opening survey of
residences on DeCola Ponds E and F conducted in 1978.
Barr. 2005. Detailed Assessment of Phosphorus Sources to Ramsey -Washington Metro Watershed District.
Prepared for the Ramsey -Washington Metro Watershed District.
Barr. 2009. City of Golden Valley Surface Water Management Plan. Prepared for the City of Golden
Valley.
Barr. 2011. Impervious Surface Reduction Incentive Program -Analysis of Water Quality/Quantity Benefits
and Stormwater Management Costs. Prepared for the Ramsey -Washington Metro Watershed District.
Barr. 2012. DeCola Ponds Area Flood Mitigation Study. Prepared for the City of Golden Valley.
Bonestroo. 2006. Report for Terra Linda Drive, Rosalyn Court, and Medicine Lake Road - Local Flood
Improvement Project. Prepare for the City of New Hope.
City of Crystal. 2014. Zoning Code.
City of Golden Valley. 2014. Golden Valley City Code - Sections 11.70,12.20, and 12.42.
City of New Hope. 2014. City of New Hope City Code - Chapter 4.
Environmental Protection Agency. 2014. Best Management Practices: Green Parking
(1 A_:, ,� water.eoa.gov/polwaste/npdes/swbmp/Green-Parking.cfm). Website accessed August 1, 2014.
United States Army Corps of Engineers. 2003. Economic Guidance Memorandum (EGM) 04-01, Generic
Depth -Damage Relationships for Residential Structures with Basements. October 10, 2003.
United States Army Corps of Engineers. USACOE commercial and industrial flood damage survey primary
survey form. As provide by Jeffery McGrath on 5/5/2014.
United States Department of Commerce - Weather Bureau. 1961. Technical Paper No. 40 Rainfall
Frequency Atlas of the United States.
United States Department of Commerce - National Oceanic and Atmospheric Administration. 2013.
Precipitation Frequency for Midwestern States, USA - NOAA Atlas 14 Volume 8.
P:\Mpls\23 MN\27\23271358 Med Lk Rd-Winnetka Mitig Plan\WorkFiles\Memo_Phasel\MLRWA_Plan_Phasel_Memo_09052014.docx
Appendix B
Medicine Lake Road and Winnetka Avenue Long -Term Flood
Mitigation Plan _ Strategies For Financial Implementation Memo
April 23, 2015
resourceful. naturallY- BARB
engineering and envirorrdnibril 11 sr,r��,alrnnrs
Memorandum
To: Jeff Oliver, Bob Paschke, and Mark Ray
From: Karen Chandler, P.E., Jennifer Koehler, P.E., and Len Kremer, P.E.
Subject: Medicine Lake Road and Winnetka Avenue Long -Term Flood Mitigation Plan -
Strategies for Financial Implementation
Date: April 23, 2015
Project: 23271358
c: Tom Burt, Kirk McDonald, and Anne Norris
This memo outlines strategies to finance implementation of the flood mitigation alternatives, made up of
two main parts:
1. Project cost allocation and financing, including approaches for allocating costs to beneficiaries
and between the cities, and methods for financing project costs,
2. Implementation commission—the structure and function of a commission, made up of members
of all three cities, which would oversee the implementation of the Medicine Lake Road and
Winnetka Avenue Area Long Term Flood Mitigation Plan (MLRWA Plan).
1.0 Background
At the January 23, 2015 meeting of staff from the Cities of Golden Valley, New Hope, and Crystal, Barr
presented the results of the flood mitigation alternatives analysis and the results of the benefit -cost
analysis. The group discussed three (3) alternatives:
• Alternative 1: Do Nothing (Existing Conditions)
* Alternative 2: Acquisition and Flood Proofing Only
Alternative 3: Flood Mitigation Projects (followed by any necessary acquisitions or flood
proofing)
Based on the discussion, the three cities agreed that Alternative 1 (Do Nothing) is not an option as it does
not address the flooding of Medicine Lake Road and the public safety issues resulting from this
alternative. Additionally, all 39 properties will remain at -risk of flooding.
Alternative 2, which only considers acquisition (flood depths > 3 feet) and flood proofing (flood depths <
3 feet) of at -risk properties, would result in acquisition of 20 properties and flood proofing of 19
Burr Engineering Co. 4700 West 77th Street, Suite 200, Minneapolis, MN 55435 959-.832.2600 www.barr.com
To: Jeff Oliver, Bob Paschke, and Mark Ray
From: Karen Chandler, P.E., Jennifer Koehler, P.E., and Len Kremer, P.E.
Subject: Medicine Lake Road and Winnetka Avenue Long -Term Flood Mitigation Plan - Strategies for Financial
Implementation
Date: April 23, 2015
Page: 2
properties. The estimated cost of this alternative is approximately $12.3 million, with a benefit -cost ratio
less than 1.0. Typically, FEMA considers funding projects with a benefit -cost ratio greater than 1.0.
Although this alternative will reduce damages to the at -risk structures, it will not reduce the flooding of
Medicine Lake Road or the associated public safety concerns. Additionally, this alternative is not preferred
by the City of Golden Valley because of the reduction in tax revenue caused by the acquisitions (nearly all
acquisitions are in the City of Golden Valley).
Alternative 3 built on past studies and evaluated flood mitigation projects in locations identified by the
cities at the October 7, 2014 meeting. The flood mitigation project goals were to 1) identify the storage
needed to reduce the flooding on Medicine Lake Road to approximately 1.5 feet of standing water at the
low point (allowing passage of emergency vehicles) during the 100 -year event, and 2) remove structures
from the flood plain to the maximum extent possible. This alternative included incorporating storage into
the watershed at approximately 13 locations, acquisition of one property, and flood proofing of
approximately 11 properties. The estimated cost of Alternative 3, including flood mitigation, acquisitions,
and flood proofing was estimated to be $27.5 million. Alternative 3 also had a benefit -cost ratio less than
1.0.
At the January 23, 2015 meeting, staff from the three cities agreed that the solution would likely be some
combination of Alternatives 2 and 3. Although the resultant plan will not resolve every detail about every
potential project, it will provide the framework to begin addressing the flooding in the project area. The
plan will outline next steps, recognizing that the implementation of the plan is long-term and may be
dependent on opportunities (as they arise), such as road reconstruction projects, redevelopment, willing
land owners, etc. The plan will identify specific flood mitigation projects that are more critical to helping
solve the flooding problems in the Medicine Lake Road and Winnetka Avenue area, based on their
proximity to the existing flood areas and Barr's understanding of the flooding (although each individual
project will not be evaluated independently during this study). As each flood mitigation project is
implemented, the impact will need to be reevaluated using the XP-SWMM model to not only determine
the impact of a specific project but to track the cumulative impact of projects as they are implemented.
Also, the plan will provide a prioritized list of at -risk properties, ranked by depth of flooding above the
low opening for the 100 -year event, which the cities can use when either targeting or making decisions
related to acquisitions and/or flood proofing.
Table 1 below summarizes the likely alternative (between Alternatives 2 and 3), which includes the most
critical flood mitigation projects needed to help resolve the flooding around the low point on Medicine
Lake Road, and the estimated costs of the projects.
To:
From:
Subject:
Date:
Page:
Jeff Oliver, Bob Paschke, and Mark Ray
Karen Chandler, P.E., Jennifer Koehler, P.E., and Len Kremer, P.E.
Medicine Lake Road and Winnetka Avenue Long -Term Flood Mitigation Plan - Strategies for Financial
Implementation
April 23, 2015
Table 1: Summary of Critical Flood Mitigation Projects and Costs
Projects around the Medicine Lake Road Low Point
VFW (Liberty Crossing) site storage and conveyance
$1,720,000 — $3,026,00
Expansion of storage in Pennsylvania Woods, DeCola $3,272,000 — $5,724,000
Ponds B & C, and raising overflow from DeCola Pond
C to D
Rosalyn Court area storage
Yunker Park storage
Projects around DeCola Ponds E & F
Diversion from DeCola Pond F & storage
development east of the railroad and around
Isaacson Park
Develop storage at School of Engineering and Arts
(SEA) School
Acquisition and Flood Proo fing2
Acquisition
Flood proofing
$493,000 — $863,000
$864,000 — $1,512,000
$1,936,000 — $3,388,000
$1,701,000 — $2,977,000
$4,173,0003
$1,016,000
1- Planning level cost estimates reflect 2015 dollars and reflect a range of uncertainty (-20% to +40%) due
to the conceptual nature of the design (10-15% design completion). Costs assume soils are not
contaminated and will not require special disposal. Costs also include planning level estimates for
expected easement acquisitions based on current property ownership. Project costs will change with
further design.
2 - This specific combination of flood mitigation alternatives was not evaluated in XP-SWMM. Therefore,
estimated costs assumed acquisition of Rosalyn Court property and the most at -risk properties on the
DeCola Ponds—those with >5 ft of flood depth under existing conditions 100 -year (approx. 4 properties).
We assumed the flood proofing costs are the same as in Alternative 2.
3 - Acquisition costs used taxable market values obtained from the 2014 Hennepin County parcel data,
which were based on January 2013 valuations by the county assessor.
To:
From:
Subject:
Date:
Page:
Jeff Oliver, Bob Paschke, and Mark Ray
Karen Chandler, P.E., Jennifer Koehler, P.E., and Len Kremer, P.E.
Medicine Lake Road and Winnetka Avenue Long -Term Flood Mitigation Plan - Strategies for Financial
Implementation
April 23, 2015
I
2.0 Project cost allocation and financing
2.1 Project cost allocation
Project costs can be allocated among the three cities and beneficiaries in a number of ways, including:
1. cost share based on watershed area
2. cost share based 50% on watershed area and 50% on taxable market value
3. cost share based on existing runoff volumes
4. cost share based on runoff volumes above pre -settlement conditions
5. cost share based on required storage volume
6. beneficiaries pay more
7. cost allocation based on combinations of cost allocation methods
The above cost allocation methods are described in Sections 2.1.1- 2.1.7 below and summarized in Table
1.
For the cost allocation alternatives, we divided the project area into two focus areas: 1) the watersheds
contributing to the Medicine Lake Road low point and DeCola Ponds A -D; and 2) the watersheds
contributing to DeCola Ponds E - F. The watershed area to Medicine Lake Road and DeCola Ponds A - D
were combined together because the two areas are connected and act as one during larger storm events.
Additionally, the connection between the two areas will be even greater once the proposed larger
conveyance is constructed between Medicine Lake Road and DeCola Ponds A - D.
The cost allocation alternatives considered the incremental (direct) and cumulative watersheds.
Additionally, the cost allocation methods broke down the costs according to 1) the three participating
cities, and 2) the three participating cities and Hennepin County (based on the CSAH right of way through
the project area).
2.1.1 Cost share based on watershed area
In this method, costs would be allocated based on the watershed area to Medicine Lake Road and DeCola
Ponds A - D, and to DeCola Ponds E - F. There are two ways that this method could be applied - by
incremental (direct) tributary area, or by cumulative tributary area. Table 3 shows the cost allocation,
along with the details of the basis for the allocation.
2.1.2 Cost share based 50% on watershed area and 50% on taxable market value
In this cost sharing method, the project costs would be allocated based 50 percent on watershed area and
50 percent on the taxable market value of all real property in the watershed. Taxable market values were
To:
From:
Subject:
Date:
Page:
Jeff Oliver, Bob Paschke, and Mark Ray
Karen Chandler, P.E., Jennifer Koehler, P.E., and Len Kremer, P.E.
Medicine Lake Road and Winnetka Avenue Long -Term Flood Mitigation Plan - Strategies for Financial
Implementation
April 23, 2015
4
obtained from the 2014 Hennepin County parcel data, which were based on January 2013 valuations by
the county assessor.
The equation for the cost allocation per entity (city or county) is:
Entity cost allocation = total project cost * [0.5*(entity's watershed area/total watershed area) +
0.5*(entity's taxable market value/total taxable market value)]
As above, there are two ways that this method could be applied - by incremental (direct) tributary area, or
by cumulative tributary area.
Allocating costs based 50% on watershed area and 50% on taxable market value is a typical method for
allocating non -capital improvement costs among cities that are part of a watershed management
organization joint powers agreement (e.g., Bassett Creek WMC). These organizations apply the method to
the cumulative tributary area.
Table 4 shows the cost allocation, along with the details of the basis for the allocation.
2.1.3 Cost share based on existing runoff volumes
In this cost sharing method, the project costs would be allocated according to the existing 100 -year
watershed runoff volumes to Medicine Lake Rd and DeCola Ponds A - D, and to DeCola Ponds E - F. The
existing watershed runoff volume from each city (and Hennepin County) was based on the subwatershed
runoff volumes predicted by the XP-SWMM modeling, which was then allocated to the cities (and
Hennepin County) within each subwatershed (by area). There are two ways that this method could be
applied - by incremental (direct) tributary area, or by cumulative tributary area. Each entity's cost
allocation is based on its existing watershed runoff volume compared to the total existing watershed
runoff volume.
Table 5 shows the cost allocation for this method, along with the details of the basis for the allocation.
2.1.4 Cost share based on runoff volumes above pre -settlement conditions
There are two ways this cost sharing method could be applied:
1. Each city would pay for projects in their city until watershed runoff volumes are reduced to the
watershed runoff volumes under pre -settlement conditions (i.e., pre -development conditions).
Under this scenario, each city would be responsible for acquiring or flood proofing homes that lie
within the "pre -settlement conditions" 100 -year floodplain. For example, if ten homes are located
To: Jeff Oliver, Bob Paschke, and Mark Ray
From: Karen Chandler, P.E., Jennifer Koehler, P.E., and Len Kremer, P.E.
Subject: Medicine Lake Road and Winnetka Avenue Long -Term Flood Mitigation Plan - Strategies for Financial
Implementation
Date: April 23, 2015
Paae:
in the floodplain of DeCola Ponds under pre -settlement conditions, the City of Golden Valley
would be responsible for the acquisition and/or floodproofing costs for these homes.
If more flood mitigation projects are required after each city reduces their watershed runoff
volumes to pre -settlement conditions, then one of the other cost share methods would need to
be applied to allocate the remaining project costs.
2. Each city would pay for projects based on their share of the increase in watershed runoff volume
above pre -settlement conditions.
For this method, we assumed native/pre-settlement conditions to be a mixture (50 percent/50 percent) of
oak forest and tall grass prairie (note: the draft BCWMC plan states that prior to settlement, "a
predominantly oak forest interrupted by tall grass prairie and marsh covered" the portion of the
watershed from the Mississippi River to Medicine Lake). We also assumed that under pre -settlement
conditions, the watershed would have no impervious surfaces, all soils would be classified as hydrologic
soil group B, and the subwatersheds would be the same as under existing conditions. Barr ran the XP-
SWMM model under native/pre-settlement conditions and used the predicted 100 -year runoff volumes
from the model, compared to the existing 100 -year runoff volumes, to develop the cost allocations.
This method is similar to the Lower Mississippi River WMC's "allowable flow' cost allocation; however the
allowable flow calculation is based on flows using the rational equation (Q=CIA), not runoff volumes.
Table 6 shows the cost allocation for this method, along with the details of the basis for the allocation.
2.1.5 Cost share based on required storage volume
In this cost sharing method, the costs would be allocated based on the required storage volume needed
for all of the proposed projects and then divided up by tributary watershed. However, the cost allocation
percentages resulting from the application of this method would be the same as the results of the
"existing runoff volumes" method (see Section 2.1.3).
2.1.6 Beneficiaries pay more
In this cost sharing method, beneficiaries would pay more. For example, the Shingle Creek and West
Mississippi WMC (SCWM) plan calls for project costs to be apportioned so that the "area directly
benefiting from the project should be apportioned 25 percent of the cost of the project." The plan gives
the example of apportioning according to proportion of lake or stream footage. The SCWM plan further
calls for 50 percent of the cost to be "apportioned based on contributing/benefiting area." The
percentages only total 75 percent because the SCWM requires the member cities to pay for 75 percent of
To: Jeff Oliver, Bob Paschke, and Mark Ray
From: Karen Chandler, P.E., Jennifer Koehler, P.E., and Len Kremer, P.E.
Subject: Medicine Lake Road and Winnetka Avenue Long -Term Flood Mitigation Plan - Strategies for Financial
Implementation
Date: April 23, 2015
Page:
project costs. Applying this philosophy to the MLRWA project would mean 1/3 of the project costs would
be apportioned according to "benefit" and 2/3 of the project costs would be apportioned based on
contributing area. The "benefits" part of this method may unfairly cause downstream properties to bear
the brunt of the cost, especially if we consider the "pre -settlement conditions" runoff volume.
One approach could be to set up overlay districts in zones closest to flooded areas. A greater portion of
the costs would be allocated to areas in the zone (or zones) closest to the flood zone. Another approach
could be apportion a percentage of the costs (say 10 percent) to be paid by the property owners within
the existing 100 -year floodplain. The amount charged to each property owner would be based on the
assessed valuation of the property.
2.1.7 Cost allocation based on combinations of cost allocation methods
The cities could decide to allocate costs based on combinations of the above methods, e.g.,
■ 50% watershed area/50% runoff volume (current conditions or natural conditions)
1/3 watershed area, 1/3 runoff volume, 1/3 taxable market value
2.2 Project financing
Cities finance capital improvement projects using a variety of tools, including:
• bonds
■ storm sewer improvement district
tax increment financing district
• tax abatement
stormwater utility fees
outside funding sources
The above financing methods are described in Sections 2.2.1- 2.2.5 below.
2.2.1 Bonds
Cities borrow money by issuing and selling municipal bonds, also known as general obligation bonds.
Cities have limits on the amount of debt they can take on through issuing and selling bonds. The current
"net debt" limit is 3% of the estimated market value of taxable property in the city (from 2014 Handbook
for Minnesota Cities, League of Minnesota Cities).
Other types of bonds include:
To: Jeff Oliver, Bob Paschke, and Mark Ray
From: Karen Chandler, P.E., Jennifer Koehler, P.E., and Len Kremer, P.E.
Subject: Medicine Lake Road and Winnetka Avenue Long -Term Flood Mitigation Plan - Strategies for Financial
Implementation
Date: April 23, 2015
Page: 8
Revenue bonds - these bonds are tied to a specific funding stream
General obligation revenue bonds - these bonds are tied to both "full faith and credit" of the city
and a specific funding stream
■ Bonds by purpose - general obligation bonds issued for a specific purpose - not a legal
requirement, but used to conveniently identify bonds to a specific project
Bonds by user - these are also called "private activity bonds" and are used partially or entirely for
private purposes, but still tax exempt.
In some situations, city residents must vote in favor of a bond before city issuance of a bond, but there
are many exceptions to this requirement.
The cities could sell bonds to help pay for the projects. The amount each city would need to fund through
bonding would depend on the amount of funds available in its stormwater fund (fund balance) - i.e., the
smaller the fund balance, the more bonding that would be required. The bonds are rated based on the
city's bond rating.
The City of Golden Valley currently owes $80.4 million on current bonds, the City of Crystal owes $13.7
million, and the City of New Hope owes $2.4 million.
Related to this, each city has a "debt load," which is the ratio of the city's debt to its tax levy. Crystal's debt
load is 148% and Golden Valley's is 27%. New Hope's debt load was not obtained in time for this memo.
Although Crystal's debt load ($13,741,000 at the end of 2014) is higher than its property tax levy
($9,313,153), the debt is based on special assessments, which are not included in the city's tax levy. The
City of Crystal is installing storm sewer in the north part of the city (where there is currently no storm
sewer), which is putting a strain on the city's finances. Potential future bonds for the City of New Hope
include a $1.5 million bond issue for 2015, $3.6 million tax increment financing bond issue for 2015, and a
$1.8 million bond issue for 2017. In addition, New Hope may need to issue a $1.5 million bond for an
emergency water repair, and is considering a new public safety building/city hall.
2.2.1 Storm sewer improvement district
The cities may fund specialized city infrastructure by creating a storm sewer improvement district (SSID).
Cities must pass an ordinance to create an SSID. Once established, the city "may acquire, construct,
reconstruct, extend, maintain, and otherwise improve storm sewer systems and related systems" within
the SSID. The city "may also acquire, maintain and improve stormwater holding areas and ponds" for the
benefit of the SSID. The city pays for the improvements in the SSID by levying taxes on the property in the
district. Tax levies also pay for principal and interest on bonds.
To: Jeff Oliver, Bob Paschke, and Mark Ray
From: Karen Chandler, P.E., Jennifer Koehler, P.E., and Len Kremer, P.E.
Subject: Medicine Lake Road and Winnetka Avenue Long -Term Flood Mitigation Plan - Strategies for Financial
Implementation
Date: April 23, 2015
Page:
2.2.2 Tax increment financing district
Cities use tax increment financing (TIF) to fund more than local improvements. The TIF tool segregates tax
dollars from a defined area for use in developing and improving the area, which can include local
improvements. The following is from the Handbook for Minnesota Cities (2014, League of Minnesota
Cities):
TIF takes advantage of the increases in tax capacity and property taxes from development or
redevelopment before the development actually occurs to pay for public development or
redevelopment costs. The difference in the tax capacity and the tax revenues the property generates
after new construction has occurred, compared with the tax capacity and tax revenues it generated
before the construction, is the captured value. The taxes paid on the captured value are called
"increments." Unlike property taxes, increments are not used to pay for the general costs of cities,
counties, and schools. Instead, increments go directly to the development authority to repay public
indebtedness or upfront costs the city incurs in acquiring the property, removing existing structures,
or installing public services.
2.2.3 Tax abatement
Through this financing tool, cities can authorize the issuance of bonds, which are paid back with funds
collected by tax abatements. The tax is not actually forgiven (abated), but is paid normally, with the
amount of property tax levied by the city used to pay for the bonds. The following example is from the
Handbook for Minnesota Cities (2014, League of Minnesota Cities):
A city may "abate" all or a portion of city property tax on one or more parcels of real or personal
property, including machinery, for economic development purposes. And cities may issue general
obligation or revenue bonds to construct public improvements. As the property owners pay the
abated taxes, rather than the local property taxes, the payments go directly to paying off the bonds.
Tax abatement bonds do not require a referendum approval and are excluded from debt limits. However,
in any year, the total amount of property taxes abated by a city may not exceed 10 percent of the net tax
capacity of the city for the taxes payable year applicable to the abatement or $200,000, whichever is
greater.
2.2.4 Stormwater utility fees
The three cities have stormwater utilities that generate fees that could be used to help pay for the
identified projects. The stormwater utility fees may be based on the size of the property, the type of
property, or the quantity and quality of runoff and disposal difficulties. Each of the three cities bases their
stormwater utility fees on the type of property.
To: Jeff Oliver, Bob Paschke, and Mark Ray
From: Karen Chandler, P.E., Jennifer Koehler, P.E., and Len Kremer, P.E.
Subject: Medicine Lake Road and Winnetka Avenue Long -Term Flood Mitigation Plan -Strategies for Financial
Implementation
Date: April 23, 2015
Page: 10
Below is the current status of each city's stormwater utility:
1. City of Crystal: generated $750,500 in 2014 from its stormwater utility fee (called the Storm
Drainage Fund). The city is increasing its stormwater utility fees for the next five years — in 2015
they expect to generate $819,000 in revenue. The city's stormwater utility is based on a single
family residential rate of $11.70 per quarter in 2014 and $12.60 per quarter in 2015 (this rate will
increase every year by $0.90 per quarter for five years). For commercial properties, the rate is 25
times the single family residential rate, or $292.50 per quarter in 2014 and $315.00 per quarter in
2015 (this rate will increase every year by $22.50 per quarter for five years).
2. City of Golden Valley: generated $2.2 million in 2014 from its stormwater utility fee (called an
Enterprise Fund). The city's stormwater utility is based on a residential equivalency factor of $22
per quarter. For commercial land uses, the monthly charge is $22 x 5 x acres = $110/acre per
month.
3. City of New Hope: generated $966,700 in 2014 from its stormwater utility fee, and expects to
generate $996,600 in 2015. The city's stormwater utility is based on monthly charges of $6.55 for
residential property (or $19.65 per quarter) and $9.83 (or $29.49 per quarter) for non-residential
property (2015 rates).
Cities could impose a "user surcharge" for flood mitigation on top of the usual stormwater utility fee (e.g.,
an extra $1/month per property) for properties within the MLRWA watershed. The user surcharge would
start generating additional funds and help offset the costs of providing additional storage in the
watershed. The details regarding the user surcharge, such as who pays the surcharge and for how long,
would need to be discussed and agreed upon by the three cities.
2.2.5 Outside funding sources
Project costs could be offset by obtaining grants, state funding (legislation), and other outside funding
sources.
Grants for flood reduction/management projects are more limited than for water quality improvement
projects. The Minnesota Department of Natural Resources' (MNDNR) Flood Damage Reduction grant is
the only state grant available for flood reduction projects. Under this program, the state can provide cost -
share grants to local units of government for up to 50 percent of the total cost of a project. Cities,
counties, towns, watershed districts and watershed management organizations, lake improvement
districts, soil and water conservation districts, and joint powers organizations composed of any of these
units (e.g., the potential future implementation commission discussed in Section 3.0) may apply.
To: Jeff Oliver, Bob Paschke, and Mark Ray
From: Karen Chandler, P.E., Jennifer Koehler, P.E., and Len Kremer, P.E.
Subject: Medicine Lake Road and Winnetka Avenue Long -Term Flood Mitigation Plan - Strategies for Financial
Implementation
Date: April 23, 2015
Page: 1 1
Currently, there are two different classes of grants available through the FDR Program:
1. Small grants; these grants are for projects with a total cost up to $300,000 (maximum state share
$150,000). The MNDNR grants these funds directly from general funds appropriated by the
Minnesota State Legislature. These are competitive, and are limited to available funds. Small
projects and studies are covered through this grant program.
2. Large grants; these grants are for projects with a total cost greater than $300,000 (state share
greater than $150,000). Large grant applications are received and prioritized by the MNDNR and
then presented to the Governor and the Legislature for consideration in a capital bonding bill. A
project will be funded based on its rank after prioritization and the amount of program funding
made available by the Legislature. (Note: every biennium, the Legislature appropriates funds for
these larger grants.)or flood mitigation/reduction projects to receive these funds, the projects
must be approved by the legislature (i.e., they must go through the legislative process).
The types of projects eligible for FDR grants include:
structural acquisition in the 100 -year floodplain
levees, ring dikes, and flood walls
elevating existing structures
■ flood warning systems
• public education
• flood insurance studies
■ floodplain mapping
comprehensive watershed plans
flood storage easements
• cost share on federal projects
The MLRWA Plan implementation projects would likely require a large grant (and legislative approval).
If a presidential declaration has been issued in Minnesota, FEMA pays for 75 percent of the cost of
structural acquisition, with the remaining 25 percent to be provided by the local governments. The FDR
program will pay half the local share, leaving the local government unit with only a 12.5 percent share.
The FDR program will also pay for half of the 35% nonfederal share of federal flood hazard mitigation
projects.
To: Jeff Oliver, Bob Paschke, and Mark Ray
From: Karen Chandler, P.E., Jennifer Koehler, P.E., and Len Kremer, P.E.
Subject: Medicine Lake Road and Winnetka Avenue Long -Term Flood Mitigation Plan - Strategies for Financial
Implementation
Date: April 23, 2015
Page: 12
Other potential grant sources include:
+ Hennepin County Emergency Management Department, which could provide grant funds for
flood damage reduction
• Hennepin County Environmental Services Department, the Metropolitan Council, and the
Minnesota Department of Employment and Economic Development — these agencies provide
funding for assessing and/or cleanup of contaminated (brownfields) sites.
Aside from grant funds, other potential outside funding sources include:
■ Hennepin County — Medicine Lake Road and Winnetka Avenue are county roads. In preliminary
conversations with Golden Valley staff, Hennepin County staff indicated openness to cost sharing
for implementing MLRWA projects. The cost allocations discussed in Section 2.1 take this
possibility into account.
Bassett Creek Watershed Management Commission (BCWMC) — the (draft) 2015 BCWMC
watershed management plan includes a policy that would allow this type of project to be
considered for inclusion in the BCWMC's capital improvement program (see policy 110).
3.0 Implementation commission
Assuming the cities of Crystal, Golden Valley and New Hope agree to begin implementing the projects
recommended in the MLRWA Long Term Flood Mitigation Plan, the next step is for the cities to create a
commission to oversee the implementation of the Plan. The commission members would be made up of
members of all three cities, and it would need to make the following important decisions:
1) how much each city should contribute to the plan implementation,
2) when projects should be implemented,
3) how to payout the commission's funds for project implementation, and
4) if policies or ordinances (e.g., zoning overlays) should be adopted in the MLRWA watershed.
The commission would also oversee the updating of the XP-SWMM model after implementation of each
project.
We see three options for forming the implementation commission:
1. Anew joint commission, independent of any existing joint commission
2. Part of the existing Joint Water Commission (JWC), as a new "charge" for the existing commission
3. Part of the Bassett Creek Watershed Management Commission (BCWMC), likely as a
subcommittee of the existing BCWMC
To: Jeff Oliver, Bob Poschke, and Mark Ray
From: Karen Chandler, P.E., Jennifer Koehler, P.E., and Len Kremer, P.E.
Subject: Medicine Lake Road and Winnetka Avenue Long -Term Flood Mitigation Plan -Strategies for Financial
Implementation
Date: April 23, 2015
Page: 13
In each of the forms above, the implementation commission could either be autonomous (e.g., it would
have the authority to order projects) or it could be required to bring recommendations back to the
ultimate authority (the three member cities or the BCWMC). In addition, the implementation
commission's decisions could move forward upon either a simple majority vote or a unanimous vote. The
MLRWA implementation commission would likely need to meet at least once per year to discuss projects
to be implemented, the funding of projects, and other business.
The implementation commission could establish a stakeholder advisory committee, which would include
neighborhood representatives from the watershed.
Table 7 summarizes the advantages and disadvantages of each form of the implementation commission.
To: Jeff Oliver, Bob Paschke, and Mark Ray
From: Koren Chandler, P.E.. Jennifer Koehler, P.E.. and Len Kremer. P.E.
Subject Medicine Lake Road and Wnnetka Avenue Longterm Flood Mitigation Plan w Strategies for Financial Implementatbn
Date: April 23, MIS
Page: I a
Table 2. Summary of Cost Allocation Methods Results
— Taxable marketvaILes obtained from the 2014 Hennepin County parcel data, which were based on January 2013 valuations by the county assessor.
To MLR & DeCola Ponds A -D
I
To DeCola Ponds E -F
Increase In
tntrrese)n
Fn11hX
W�1ert+uerl
Existing
Runoff
Watershed
Existing
Runatl
watentrrd
Area & 50%
Ranoff
Vohume
Watershed
alree 50%
V4 ikime
Area Only
T.. ""
v olum:es
from Pre-
Area Only
Taxable
Volume'
atixr
from HNat
Market Values
(100 -Yr)
WIlteunuml
Market Value
(100 -Yr)
condlllons
Candittons
Crystal
31%
32`6
26%
3D%
0%
o%
M
0%
New Hope
37%
32%
27
31%
3646
16%
41411
0%
096
0%
Ft%
Golden Valley
100% MA%
lOA
100%
Total _
_ _ _WO%
111O'A
111111.4;IN%
100%
JIM
100%
1110%
To MLR & DeCola
Ponds A -D
To bdutr Perdr
14
_
50%ta
lntr.+rf+.u.
Increase In
Irrat+rsll�a
Existing
Runoff
50% WeEvshed
Existing
RLnaf!
r�llky
Watenluesl
Runoff
Volume
Watershed
Araa & S41%
Runoff
Area Only
A a & 5055
Valumcs
Foam Pre
Area Only
Tox Wa MaribrL
Volume'
Volume
Taxable
Ti
Market Value'
(100 -Yr)
xtLlern!mt
W.N.N.
(100 -Yr)
trorn Native
Conditions
4onditioas
Crystal
]C a.
32%
2,%
:915
0%
RAF
0%
0%
New Hope
36%
36%
36'11
n%
0%
G1.6
0%
0%
Golden Valley
30AE
_ 30%
'tM
i'IL
7.00%
100
100%
100%
Hennepin County
4%
2%
5%
*%
0%
GK
0%
D%
Total
B. Cumulative Summary
200%
100%
LO %
Ire%
100%
1010%
100%
)DO%
To MLR & DeCola Ponds A -D
Entire Watershed to D&Wa Ponds E -F
50y;
Existing
fn.a ray:. if.
Runulf
5G%Walarahaif
Existing
Increase In
Drd"VI';let-11-1
Wit31W
Rwldff
Vatenlii
Watershed
Anse&5016
Runoff
Rmuff
Volum
Area Only
h+sa fk se%
Tasabla
Volumes
from Pxe-
Area Only
Taxable Market
Volumes
Volume
From Native
Market Valuer
(100 -Yr)
settlement
(100 -Yr)
Conditions
Conditions
'
Conditions
Crystal
31%
32%4
1 26%
30%
7345
7JT{I
2341
17%6
19%%
27%
22%
30%
New Hope
37'a;
3.2%
37%
J1,=
35%
41%
Golden Valley
M%
29%
49%
50%
55%
49%
row
IDO%
DTT
ion%
100%
100%
1D(I%
15OR6
IQ474
To Mil[ tk DeCeln Porh&*D
Entire Watershed to DeCola Ponds E -F
54
Increase in
Increase in
Existing
Runrvrr
50% Watershed
Existing
kulnoff
1Y
Watershed
SD
Runoff
Volume
Watarstrad
Aram& 50%
RwnuFf
Area Only
paqWaiIN
APa4 er 5
Volumes
fMm l'tm-
Area Only
Taxable Market
Volumes
of
VclNod
Texabkn s
Market Value
(100 -Yr)
settlensent
Yel4r`
(100 -Yr)
fr',rnrl Nrt1'R
Conditions
Condations
Cryrtal
3G%
32%
2b%
2elic
22%
2M
18A4
71%
New Hope
36%
36%
M%
39%
27%
48%
3bi1
SO%
?3'26
20%
Golden Valley
.91% 1" 341► 211%
53%
4041:
Hennepin County
4%5
3%
5`X _
4%
3%
Total
10094
r00%
IPO%
f(>
IIX7%
IOD%
IM
WM
— Taxable marketvaILes obtained from the 2014 Hennepin County parcel data, which were based on January 2013 valuations by the county assessor.
To: Jeff Oliver, Bob Paschke, and Mark Ray
From: Karen Chandler, P.E., Jennifer Koehler, P.E., and Len Kremer, P.E.
Subject: Medicine Lake Road and Winnetka Avenue Long -Term Flood Mitigation Plan - Strategies for Financial
Implementation
Date: April 23, 2015
Page: 15
Table 3. Cost Share Based on Watershed Tributary Area
A. Incremental Summary
To MLR & DeCola Ponds A -D
Entity Watershed Area Watershed Area
(ac) (%)
To DeCola Ponds E -F
Watershed Area Watershed Area
(ac) (%)
Crystal
139
170
31%
37%
0 0%
0 1 0%
150 100%
New Hope
Golden Valley
146
32%
Total
455
100%
150 100%
Entity
To MLR & DeCola Ponds A -D
Watershed Area Watershed Area
(ac) (%)
To DeCola
Watershed Area
(ac)
Ponds E -F
Watershed Area
(%)
Crystal
136
30%
0
0%
New Hope
Golden Valley
163
36%
0
0%
139 30%
18 1 4%
455 100%
150
100%
Hennepin County
0
150
1 0%
Total
B. Cumulative Summary
100%
Entity
To MLR & DeCola Ponds A -D
Entire Watershed to DeCola Ponds E -F
Watershed Area Watershed Area
(ac) (%)
Watershed Area
(ac)
Watershed Area
(%)
Crystal
139 31%
139
23%
New Hope
170 37%
170 1
28%
Golden Valley
146 32%
296
49%
Total
455 100%
605
100%°
Entity
To MLR & DeCola Ponds A -D Entire Watershed to DeCola Ponds E -F
Watershed Area Watershed Area Watershed Area Watershed Area
(ac) (%) (ac) (%)
Crystal
136
30%
36%
136
22% _
27%
New Hope
163
163
Golden Valley
139
30%
289
48%
Hennepin County
18
455
4%
100%
18
605
3%
100%
Total
A gi
a
R
�
a
a
cd
o6
Q
}
6'
4
v
as
saa¢
3c w
a
c
Jf
A
q
� q
Zl
2
>
m
=
j
c
V
5
v
i
12
No
u
w
}4
v
� A
I
4
5Q
u�
o
O
0
0
O
00
V'
S
o
q
p
vet
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O
OL
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0
To: Jeff Oliver, Bob Paschke, and Mark Ray
From: Karen Chandler, P.E., Jennifer Koehler, P.E., and Len Kremer, P.E.
Subject: Medicine Lake Road and Winnetka Avenue Long -Term Flood Mitigation Plan -Strategies for Financial
Implementation
Date: April 23, 2015
Page: 18
Table 5. Cost Share Based on Existing Runoff Volumes
A. Incremental Summary
Entity
To MLR & DeCola Ponds A -D
Existing Existing
Conditions 100- Conditions 100 -Yr
Yr Runoff Runoff Volume
Volume (ac -ft) (%)
To DeCola Ponds E -F
Existing
Conditions 100-
Yr Runoff
Volume (ac -ft)
Existing
Conditions 100 -Yr
Runoff Volume
(%)
C rystal
47
26%
38%
11
ti:
0%
New Hope
68
0%
Golden Valley
64
36%
14
100%
Total
179
100%
74
100%
To MLR & DeCola
Existing
Fntity Conditions 100-
Yr Runoff
Volume (ac -ft)
Ponds A -D
To DeCola Ponds E -F
Existing
Conditions 100 -Yr
Runoff Volume
(%)
Existing Existing
Conditions 100- Conditions 100 -Yr
Yr Runoff Runoff Volume
Volume (ac -ft) (°/U)
Crystal
46
26%
0
0%
New Hope
6436%
,i
4
0%
Golden Valley
Hennepin County
Total
61
8 I
179
34%
_ 5%
100%
74
0
100%
0%
74
100%
To: Jeff Oliver, Bob Paschke, and Mark Ray
From: Karen Chandler, P.E., Jennifer Koehler, P.E., and Len Kremer, P.E.
Subject: Medicine Lake Road and Winnetka Avenue Long -Term Flood Mitigation Plan - Strategies for Financial
Implementation
Date: April 23, 2015
Page: 19
Table 5. Cost Share Based on Existing Runoff Volumes
B. Cumulative Summary
To MLR & DeCola
Existing
Entity Conditions 100-
Yr Runoff
Volume (ac -ft)
Ponds A -D I Entire Watershed to
DeCola Ponds E -F
Existing
Conditions 100 -Yr
Runoff Volume
(%)
Existing Existing
Conditions 100 -Yr Conditions 100-
Runoff Volume Yr Runoff
(%) Volume (ac -ft)
Crystal
47 26%
47
19%
New Hope
68
38%
68
27%
Golden Valley
Total
64
36%
100%
138
55%
179
253
100%
To MLR & DeCola
Existing
Conditions 100-
Yr Runoff
Volume (ac -ft)
Crystal 46
Ponds A -D
Entire Watershed to
DeCola Ponds E -F
Existing
Conditions 100 -Yr
Runoff Volume
(%)
18%
25%
Existing
Conditions 100 -Yr
Runoff Volume
(%)
26%
Existing
Conditions 100-
Yr Runoff
Volume (ac -ft)
46
64
New Hope I
Golden Valley
64
61
36%
3490
135
53%
Hennepin County
8
5%
8
3%
1(k7%
Total
179
100%
253
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To: Jeff Oliver, Bob Paschke, and Mark Ray
From: Karen Chandler, P.E., Jennifer Koehler, P.E., and Len Kremer, P.E.
Subject: Medicine Lake Road and Winnetka Avenue Long -Term Flood Mitigation Plan — Strategies for Financial
Implementation
Date: April 23, 2015
Page:
Table 7. Forms of Implementation Commission: Advantages and Disadvantages
Features
Could be similar in structure and
function as the existing Joint Water
Commission, e.g.,:
+ Three voting members, one each
from Crystal, Golden Valley and
New Hope
• Members appointed by their
respective city councils through a
resolution
Features
Same structure and function as the
Joint Water Commission:
• Three voting members, one each
from Crystal, Golden Valley and
New Hope
• Members appointed by their
respective city councils through a
resolution
The JWC actions require a 2/3 vote,
except for actions such as capital
improvements, which require a
unanimous vote.
Features
Likely a three-member subcommittee
of the nine -member BCWMC.
The three members would likely be
the sitting commissioners from the
cities of Crystal, Golden Valley and
New Hope (or their alternate
commissioners, should the
commissioner be absent).
Advantages
Because it's similar to the existing
JWC, there is a level of familiarity
with how the new commission
would work.
New commission with a sole charge
of implementing the MLRWA Long -
Term Flood Mitigation Plan.
Advantages
Each city is familiar with how the
JWC functions.
Would require amendment to
existing joint powers agreement, but
may only require minor changes.
Can purchase, hold and sell
property.
Advantages
Each city and the state agencies are
familiar with how the BCWMC works.
Would require amendment to
existing joint powers agreement, but
may only require minor changes.
Disadvantages
Need to form a new commission
with a newjoint powers agreement.
New joint powers agreement
requires signatures of all three
member cities.
Disadvantages
Flood reduction/mitigation is
different than drinking water—easier
for the city councils and the public
to envision the benefits of paying for
drinking water projects than flood
reduction/mitigation projects
Would require amendment to
existing joint powers agreement,
which may require major changes.
Amended joint powers agreement
requires signatures of all three
member cities. If not signed by all
three member cities, would threaten
existence of the JWC.
Disadvantages
Would require amendment to
existing joint powers agreement,
which may require major changes.
Amended joint powers agreement
requires signatures of all nine
member cities. If not signed by all
member cities, would threaten
existence of the BCWMC.
The subcommittee would likely make I I Would require major amendment to
To: Jeff Oliver, Bob Paschke, and Mark Ray
From: Karen Chandler, P.E., Jennifer Koehler, P.E., and ten Kremer, P.E.
Subject: Medicine Lake Road and Winnetka Avenue Long -Term Flood Mitigation Plan - Strategies for Financial
Implementation
Date: April 23, 2015
Page: 23
Table 7. Forms of Implementation Commission: Advantages and Disadvantages
recommendations to the full BCWMC,
which would have the ultimate
decision authority.
the BCWMC Plan to allow for this
new structure and potential new
funding mechanisms.
The BCWMC's obtains its CIP
funding through an ad valorem tax
request to Hennepin County, which
must be approved by the county
board.
The BCWMC cannot purchase, hold,
and sell property.
The BCWMC cannot levy for
maintenance of capital projects,
unless special legislation approved
by the state legislature.
Appendix C
Medicine Lake Road and Winnetka Avenue Long -Term Flood
Mitigation Plan - Summary of Alternative 2,5
February 16, 2016
resourceful. naturally. BAR
.::�CtiI��Sr�(iU _,c�.l �+n•.virF�.ninr-1x71 _�arssVll4�lt5
Memorandum
To: Jeff Oliver, Bob Paschke, and Mark Ray
From: Karen Chandler, P.E. and Jennifer Koehler, P.E.
Subject: Medicine Lake Road and Winnetka Avenue Long -Term Flood Mitigation Plan —
Summary of Alternative 2.5
Date: February 16, 2016
Project: 23/27-1358
c: Tim Cruikshank, Kirk McDonald, and Anne Norris
1.0 Background
At the April 30, 2015 meeting of the city staff of the Cities Golden Valley, New Hope, and Crystal, Barr
presented the potential cost -share methodologies and financial implementation strategies for the
Medicine Lake Road and Winnetka Avenue Long -Term Flood Mitigation Plan. At the outcome of this
meeting, the various city staff requested the following additional work:
• Evaluation of Alternative 2.5 (the most likely scenario which includes a combination of flood
mitigation projects along with voluntary acquisition and flood proofing). Alternative 2.5 is a
combination of Alternatives 2 and 3 which were presented to the Cities of Golden Valley, New
Hope, and Crystal on January 23, 2015. At that time, the Cities agreed that the most likely
alternative was some combination of Alternatives 2 & 3. The flood mitigation projects would be
evaluated in a stepwise fashion to provide an understanding of the number of potential voluntary
acquisitions or flood proofing required as different projects are implemented. Additionally, all
acquisition costs would be revised to no longer include relocation costs as the Cities see these
acquisitions as voluntary.
■ Development of three additional cost -share scenarios as outlined by City staff at the April 30,
2015 meeting and application to one project example in each City.
Development of a memo summarizing the additional analyses above and presentation to the city
staff of the Cities of Golden Valley, New Hope, and Crystal.
Ultimately, the goal of this flood mitigation planning effort is to protect public safety and reduce flood
risk while minimizing the number of voluntary property acquisitions. The Cities recognize that in the case
of this flood area, the voluntary property acquisitions will primarily impact single family residential
properties and the neighborhood, and will also reduce the tax base,
Barr Engineering Co. 4700 West 77th Street, Suite 200, Minneapolis, MN 55435 952.832.2600 www.barr.com
To:
From:
Subject:
Date:
Page:
Jeff Oliver, Bob Paschke, and Mark Ray
Karen Chandler, P.E. and Jennifer Koehler, P.E.
Medicine Lake Road and Winnefka Avenue Long -Term Flood Mitigation Plan - Summary of Alternative 2.5
February 16, 2016
2.0 Alternative 2.5 Summary
Barr utilized the existing XP-SWMM model to evaluate Alternative 2.5 for the Atlas 14, 100 -year design
storm event. The modeling of the various components of Alternative 2.5 was performed in the order
below, with each component building on the previous:
1) Component 1: Proposed storage as part of the Liberty Crossing development, including
conveyance along Rhode Island (based on most current conceptual design), the expansion of
storage in Pennsylvania Woods and DeCola Ponds B & C, and raising the natural overflow from
DeCola Pond C to D
2) Component 2: Development of flood storage at Rosalyn Court and the development of
additional storage in Yunker Park
3) Component 3: Diversion of flows away from DeCola Pond F, including development of storage in
the area around Isaacson Park (assuming development of additional storage on the south end of
the park and utilization of an entire industrial parcel for both water quality improvement and
flood mitigation), and development of storage around the School of Engineering and Arts (SEA)
school.
4) Component 4: Additional storage as needed to best achieve the goal of 18 inches (or less) of
standing water at the low point on Medicine Lake Road
The order of the components outlined above was based on first reducing flooding around Medicine Lake
Road, followed by implementation of the projects that will help reduce flooding on DeCola Ponds D, E,
and F at the downstream end of the system. Portions of Component 1 are already being pursued with
redevelopment in the watershed. However, the actual sequencing of the other flood mitigation projects is
flexible and will be based on opportunities within the watershed and availability of funding.
In addition to evaluating the impact of the various flood mitigation components on the peak flood
elevations for the 100 -year event, the costs were summarized for each component or phase of
implementation. The results of the analysis of Alternative 2.5 are discussed in more detail in the following
sections.
2.1 Impact on Flood Elevations and At -Risk Properties
For each phase of implementation, we used the XP-SWMM model to evaluate the impact of flood
mitigation projects on the Atlas 14 100 -year design storm peak flood elevation at key locations within the
project area (See Figure 1), and the resulting impact on the estimated number of properties identified for
voluntary acquisition or flood proofing. For this study, Barr identified at -risk structures with greater than 3
feet of flooding above the low opening for acquisition while at -risk structures with less than 3 feet of
flooding above the low opening were identified for flood proofing. Additionally, for each component,
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To: Jeff Oliver, Bob Paschke, and Mark Ray
From: Karen Chandler, P.E. and Jennifer Koehler, P.E.
Subject: Medicine Lake Road and Winnetka Avenue Long -Term Flood Mitigation Plan - Summary of Alternative 2.5
Date: February 16, 2016
Page: 6
Table 1 summarizes the existing conditions peak flood elevations for the Atlas 14100 -year design event
at key locations in the watershed as well as the expected peak flood elevation upon implementation of
each component.
Table 1 Key Flood Areas and 100 -year Flood Elevation Summary for Alternative 2.5
Component 1: Proposed storage as part of Liberty Crossing, Pennsylvania Woods, and DeCola Ponds B and C expansion
Component 2: Proposed storage as part of Rosalyn Court and Yunker Park (in addition to Component 1)
Component 3: Proposed storage as a part of the SEA School and Isaacson Park/Industrial Parcel with full parcel grading
(in addition to Components 1 & 2)
Alternative
Alternative
Alternative
Flood
Existing
Flood Area Description
2.52.5
2.5
Area
Conditions
Component 11
Component 21
Component 3
1
Terra Linda Low Point
905.6
905.5
905.5
905.5
Medicine Lake Road
Low Point/Rosalyn
2
Court 905.1 902.0
901.8
90.1.8
Rhode Island Ave Low
3
Point
904.1
902.0
901.8
901.8
4
Dover Hill Apartments
902.6
902.0
901.8
901.8
5
DeCola Pond A
902.6
901.9
901.8
901.8
F,
DeCola Pond B
902.6
902.0
901.8
901.8
7
DeCola Pond C
902.6
902.0
901.8
901.8
8
DeCola Pond D
902.7
901.8
900.0
899.2
9
DeCola Pond E
896.2
895.8
895.8
894.0
10
DeCola Pond F
895.9
895.8
895.8
893.7
Medicine Lake Road
_
11
East of Railroad
East of Railroad to
912.2
912.2
912.2
912.2
1
DeCola Pond C
902.7
902.4
902.2
902.2
East of Railroad at Low
13
Point on Nevada
903.0
903.0
903.0
903.0
East of Railroad at Low
14
Point on Sandburg
902.3
902.3
902.3
902.3
East of Railroad to
15
DeCola Pond F
Honeywell Pond
901A
901,4
901.4
900.0
16 I
88 3.,2
884.2
L 884,2
884.2
Component 1: Proposed storage as part of Liberty Crossing, Pennsylvania Woods, and DeCola Ponds B and C expansion
Component 2: Proposed storage as part of Rosalyn Court and Yunker Park (in addition to Component 1)
Component 3: Proposed storage as a part of the SEA School and Isaacson Park/Industrial Parcel with full parcel grading
(in addition to Components 1 & 2)
To: Jeff Oliver, Bob Paschke, and Mark Ray
From: Karen Chandler, P.E. and Jennifer Koehler, P.E.
Subject: Medicine Lake Road and Winnetka Avenue Long -Term Flood Mitigation Plan — Summary of Alternative 2.5
Date: February 16, 2016
Paae: i
Table 2 summarizes the number of at -risk properties that remain after the implementation of each
component.
Table 2 Alternative 2.5 Impact on At -Risk' Structures
At -Risk structures defined as those with low openings below the estimated 100 -Year flood elevation
Component 1: Proposed storage as part of Liberty Crossing, Pennsylvania Woods, and DeCola Ponds B and C expansion
Component 2: Proposed storage as part of Rosalyn Court and Yunker Park (in addition to Component 1)
Component 3: Proposed storage as a part of the SEA School and Isaacson Park/Industrial Parcel with full parcel grading
(in addition to Components 1 & 2)
Under existing conditions, there is approximately 5 feet of standing water at the low point on Medicine
Lake Road and there are 39 structures identified as being at -risk of flooding (the estimated 100 -year peak
flood elevation is above the surveyed low opening). Based on the stepwise evaluation of the Alternative
2.5 components, the following is a summary of the general conclusions:
• Implementation of components 1 and 2 of Alternative 2.5 will reduce flooding around the low
point on Medicine Lake Road and reduce flooding on DeCola Pond D; however, with both
components, there is only a small reduction of the peak flood elevations at DeCola Ponds E & F
(See Table 1). Implementation of components 1 and component 2 will result in the reduction of
at -risk structures by 6, primarily around Medicine Lake Road and DeCola Pond D.
Implementation of components 1, 2, and 3 from Alternative 2.5 will achieve approximately 18
inches of standing water at the low point in Medicine Lake Road which will improve public safety
and allow for emergency vehicles to travel through this area during the 100 -year flood event.
Alternative
Existing Alternative 2.5 2.5
Alternative 2.5
Conditions Component 12 Component 22
Component 32
At Risk, no Mitigation I 39
0 0
0
Proposed (Voluntary)
Acquisition 0
17 10
2
Voluntary Acquisition
(for Construction of a
Flood Mitigation Project)
0
1
2
Flood Proofing
0
16
22
23
No Flood Risk
4
10
10
16
Within V of 100 -Year
2
1
2
7
>1' of 100 -Year
2
9
8
9
Total Number of
Properties
43
43
43
43
At -Risk structures defined as those with low openings below the estimated 100 -Year flood elevation
Component 1: Proposed storage as part of Liberty Crossing, Pennsylvania Woods, and DeCola Ponds B and C expansion
Component 2: Proposed storage as part of Rosalyn Court and Yunker Park (in addition to Component 1)
Component 3: Proposed storage as a part of the SEA School and Isaacson Park/Industrial Parcel with full parcel grading
(in addition to Components 1 & 2)
Under existing conditions, there is approximately 5 feet of standing water at the low point on Medicine
Lake Road and there are 39 structures identified as being at -risk of flooding (the estimated 100 -year peak
flood elevation is above the surveyed low opening). Based on the stepwise evaluation of the Alternative
2.5 components, the following is a summary of the general conclusions:
• Implementation of components 1 and 2 of Alternative 2.5 will reduce flooding around the low
point on Medicine Lake Road and reduce flooding on DeCola Pond D; however, with both
components, there is only a small reduction of the peak flood elevations at DeCola Ponds E & F
(See Table 1). Implementation of components 1 and component 2 will result in the reduction of
at -risk structures by 6, primarily around Medicine Lake Road and DeCola Pond D.
Implementation of components 1, 2, and 3 from Alternative 2.5 will achieve approximately 18
inches of standing water at the low point in Medicine Lake Road which will improve public safety
and allow for emergency vehicles to travel through this area during the 100 -year flood event.
To: Jeff Oliver, Bob Paschke, and Mark Ray
From: Karen Chandler, P.E. and Jennifer Koehler, P.E.
Subject: Medicine Lake Road and Winnetka Avenue Long -Term Flood Mitigation Plan - Summary of Alternative 2.5
Date: February 16, 2016
Paae: n
However, implementation of component 2 only reduces the number of at -risk structures by 6
while component 3 significantly reduces flooding at DeCola Ponds E and F and reduces the
number of at -risk structures by 12. Additionally, for component 2, 11 structures were identified
for potential voluntary acquisition (1 for project construction) and 22 for floodproofing while for
component 3, the numbers for voluntary acquisition and floodproofing are 4 (2 for project
construction) and 23, respectively (See Table 2).
Because components 1, 2, and 3 achieve the goal of approximately 18 inches of standing water at
the low point of Medicine Lake Road, a 4th component was not evaluated.
2.2 Estimated Project Costs
Planning level costs were developed for each component of Alternative 2.5, including the flood mitigation
project costs and the associated voluntary acquisition/demolition and flood proofing costs.
Planning level cost estimates were developed for the various flood mitigation projects based on the
conceptual design of each project. However, there is cost uncertainty and risk associated with this
concept level of design cost estimate. The costs reported for flood mitigation projects are point estimates
and include contingencies (25 percent), engineering and design (30 percent), construction management
(10%), and estimated land acquisition/easement costs (if applicable). The costs do not include any wetland
mitigation costs and assumes that the excavated soils are not contaminated. The range of probable costs
presented reflects the level of uncertainty, unknowns, and risk due to the concept nature of the individual
project designs. We have utilized industry resources for cost estimating (ASTM E 2516-11 Standard
Classification for Cost Estimate Classification System) to provide guidance on cost uncertainty. Based on
the current level of design, the cost range varies by +40 percent to -20 percent from the planning level
cost estimate.
To estimate the cost of voluntary acquisition of at -risk properties, acquisition costs were evaluated along
with an estimate of property removal/demolition costs. Although relocation costs were originally
estimated for each at -risk property, these costs were removed from the total acquisition costs based on
feedback from City staff at the April 30, 2015 meeting, as it was assumed that any acquisitions would be
voluntary. The voluntary acquisition and removal costs for single-family residential properties were
determined using the current Hennepin County taxable market values (from 2014 Hennepin County parcel
data) and multiplying by a factor of 1.5. This factor was provided by the City of Golden Valley based on
recent property acquisition and demolition costs. Dan Wilson, a real estate appraiser subconsultant,
estimated the voluntary acquisition costs for the at -risk multi -family residential, commercial, and industrial
properties. These estimates were based on in-person interviews, use of the current Hennepin County
taxable market value, and other sources to establish market values. Removal costs were assumed to be 20
percent of the acquisition costs, based on the guidance provided by the City of Golden Valley.
To: Jeff Oliver, Bob Paschke, and Mark Ray
From: Karen Chandler, P.E. and Jennifer Koehler, P.E.
Subject: Medicine Lake Road and Winnetka Avenue Long -Term Flood Mitigation Plan - Summary of Alternative 2.5
Date: February 16, 2016
Page: 9
Planning level floodproofing costs were based on previous floodproofing projects and the estimated
depth of flooding above the low opening of the structure.
To account for potential increases in market values for voluntary acquisition and uncertainty in the
planning level flood proofing costs, the estimates were also buffered by the +40 percent to -20 percent as
was applied to the flood mitigation project costs.
Tables 3, 4, and 5 below summarize the estimated costs and the planning level cost estimate range for
each component of Alternative 2.5, which includes the most critical flood mitigation projects needed to
help improve the flooding around the low point on Medicine Lake Road and DeCola Ponds E & F.
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To: Jeff Oliver, Bob Paschke, and Mark Ray
From: Karen Chandler, P.E. and Jennifer Koehler, P.E.
Subject: Medicine Lake Road and Winnetka Avenue Long -Term Flood Mitigation Plan - Summary of Alternative 2.5
Date: February 16, 2016
Page: 14
fraction of the project that would be paid by the beneficiaries would be equally split between all
properties in the entire DeCola Pond F watershed and the direct beneficiaries (i.e., those property
owners of at -risk properties flood inundation areas, see Figure 4).
Table 6 summarizes the breakdown of the four cost -share alternatives as a percentage that would be
applied to specific projects. To help understand the difference in how the various cost -share methods
translate to actual costs, the cost -share alternatives were applied to the overall estimated planning level
project cost for Alternative 2.5, and to an individual flood mitigation project in each city. These costs are
summarized in Table 7.
For cost -share alternatives 2 through 4, which include the beneficiaries paying more approach, some of
the cost would be allocated to property owners within the entire DeCola Pond F watershed and would
potentially be applied as a special assessment on the property. To understand the average annual impact
on each individual property, we needed to estimate the recovery period of these assessments. Based on
response from City staff, the following are the typical recovery periods for special assessments:
• The City of Golden Valley special assessments recovery period is typically 10 years.
The City of Crystal special assessment recovery period is 10 or 15 years, depending on the project.
For the City of New Hope, the recovery period is typically 10 years; however this is only for tax
exempt properties. All other properties within New Hope do not receive special assessments.
For the cost -share alternatives outlined above and for the beneficiaries pay more approach, the estimated
recovery period for the special assessments is assumed to be 10 years. We have also assumed that the
cost allocated to each property within the DeCola Ponds watershed is equal, regardless of property type
or value. If the cities would decide to pursue one of the beneficiaries pay more alternatives, they may
want to consider a cost allocation method that considers property type or valuation.
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