HomeMy WebLinkAboutPCD 2022-06-06 Item 1C - Discussion - Gunter Levee Design ConsiderationCity of Tukwila
Allan Ekberg, Mayor
INFORMATIONAL MEMORANDUM
TO: Planning and Community Development
FROM: Nora Gierloff, DCD Director
BY: Mike Perfetti, Senior Program Manager PW
CC: Mayor Ekberg
DATE: May 31, 2022
SUBJECT: Gunter Levee Design Considerations
ISSUE
Staff is seeking policy direction from Council on City priorities for the design of the Gunter Levee
improvements.
BACKGROUND
The Howard A. Hanson Dam and the system of levees along the Green River work together to
reduce downstream flooding in Tukwila and adjacent cities. The certification for the Tukwila 205
Levee extending along the west bank of the River from 1-405 to S. 196th Street expired in August
2013. The Tukwila Levee Accreditation Report — Phase 1 in 2015 and Phase 2 in 2018- found
that approximately 80% of the levee requires repair or reconstruction (see Attachment A). The
City is working to maintain Federal Emergency Management Agency (FEMA) accreditation
requirements. The King County Flood Control District (District) is making levee improvements to
contain the median estimate of a 500 -year flood event in a manner that will enable certification
and accreditation by the City.
Losing accreditation could potentially result in an expansion of lands mapped within the special
flood hazard area (I.e 100 -year floodplain), and subjecting development on those lands to
floodplain regulation requirements and floodplain management standards at RCW 86.16.
In 2020 Tukwila updated its Shoreline Master Program and increased the shoreline buffer width
to 125 feet landward from ordinary high-water mark in the Urban Conservancy environment for
areas with levees. This was done to preserve space for the eventual setback and
reconstruction of levees in the City. The District has agreed to begin several projects that will
address levee deficiencies and improve flood protection to the new 500 -year flood standard,
including reconstruction of the Gunter Levee, which is the subject of this informational
memorandum, and has committed $39.3 million over the next six years for the design and
construction of the project. The levee is being designed by a team from King County's Water
and Land Resources Division (WLRD, as a service provider of the District) with a multi -benefit
approach, integrating habitat restoration, flood risk reduction, and recreation.
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INFORMATIONAL MEMO
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DISCUSSION
Regarding the Gunter levee, King County has an existing easement on the adjacent privately -
owned property that varies in width, but is approximately 65 -foot -wide, paralleling the river and
includes within it an 18 -foot wide trail easement that follows the top of the existing levee. In
order to reconstruct the levee to provide 500 -year flood protection and incorporate flood storage
and habitat features necessary for on-site mitigation and to meet District goals, the District
needs to purchase an additional 60 feet or so, at a minimum, out to the 125 -foot setback and
achieve a self -mitigating project. The property owner at the Gunter site entered into a
Memorandum of Understanding (MOU) to sell the property in 2019 (Attachment B).
The Gunter levee site lies within the Tukwila South Overlay Zone (TSO). Per City code,
residential development within the TSO requires both on and off-site recreation areas be
provided for future housing. This requirement is to ensure a high quality of life for future
residents as there are no existing or planned public parks in the area. The property owner has
said that in the absence of the levee project they intended to provide much of this required off-
site recreation area within the space that King County is seeking to purchase and is referenced
in the draft MOU language. The property owner has visualized this as a linear park with a
secondary trail, see conceptual plan at 2 below.
If that strip is acquired by King County, rather than locate recreation space for future housing
elsewhere, the property owner is arguing for recreation space "credits" that would be developed
as a linear trail/park waterward of the reconstructed levee as a condition of the sale to the
District (see conceptual plans at 3, 4, and 5 below).
https://tukwilawa.sharepoint.com/sites/mayorsoffice/cc/Council Agenda Items/DCD/Gunter Levee/Gunter Levee Rec Space Memo.docx
INFORMATIONAL MEMO
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Based on earlier coordination, the property owner expressed willingness to provide this
additional 60 ft width along the river (5.88 acres area) for flood risk reduction capital project
improvements. Beyond the regional trail/maintenance road, the District likely would not
purchase property for exclusive recreational use.
Each future residential unit in the TSO is required to have 125 square feet of off-site recreation
space (in addition to 75 square feet of on-site space) so in terms of available area, this strip
could meet that off-site requirement for approximately 2,200 units'. However, to comply with
the code, the recreation area would need to meet other location and design criteria at TMC
18.41.090 in conjunction with shoreline code requirements. The code anticipates that a variety
of recreation activities be provided such as fields and sport courts which would not fit into a
linear park. The Tukwila South Master Plan and Environmental Impact Statement anticipate
development of between 700 and 1,900 residential units, hips:// .tukwiillawa.pov/wp-.
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2. Segale Concept Drawing of Linear Park within Shoreline Buffer
Policy Question:
Should recreation space "credit" be granted for land not controlled, improved, or
maintained by the property owner? For example, if Forterra purchased property in Tukwila
The code mandates a minimum recreation space requirement for new residential
developments. The property owner has indicated a willingness to construct
more recreation space in Tukwila South than would be required by City Code.
https://tukwilawa.sharepoint.com/sites/mayorsoffice/cc/Council Agenda Items/DCD/Gunter Levee/Gunter Levee Rec Space Memo.docx
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INFORMATIONAL MEMO
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South and developed a park, would the former landowner be able to count that area as off-
site recreation space for an apartment building they developed nearby?
Staff from Tukwila and King County WLRD as service provider to the District have met with the
property owner to discuss what amount of usable recreation space could be incorporated into
the levee design while continuing to meet other objectives such as flood risk reduction and fish
habitat improvements. The TSO code requirements for off-site recreation space were reviewed,
amended, and approved by the Council last year. At this time, the City is following those
requirements to define recreational area.
TMC 18.41.090 A 3 c
(4) To qualify, the proposed recreation area must be located adjacent to, and highly visible
from, a street (public or private) or trail and provide a range of active and passive
recreational opportunities (as outlined in this Chapter) for multiple ages and physical
abilities. Only those areas that are usable may count towards the off-site recreation space
requirement. The following areas are excluded: parking lots, utility sheds, inaccessible
natural/planted areas, any landscaped area required by code, and unimproved steep
slopes as defined in TMC Section 18.45.120.
(5) Larger off-site recreational areas are typically characterized by recreational activities
that serve a range of individuals and groups, such as field games, court games, craft
areas, playground apparatus, picnicking, and space for quiet/passive activities.
Neighborhood recreation areas may contain active recreational facilities such as softball,
basketball, volleyball, handball, tennis, children's play structures, trails, and grass areas
for activities and/or picnic facilities.
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3. Conceptual Levee Cross Section with additional Recreation Space along a side path
King County WLRD staff has stated that in purchasing the land, they would need to have input
on how recreation features are developed so that they can work towards achieving the self -
mitigating and multi -beneficial project, which is the intent of the property purchase. The WLRD
staff anticipates that the Green River Trail will be rebuilt atop the revised levee crest that results
from this project. It is typical for the District, in the Green River watershed, to accommodate the
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INFORMATIONAL MEMO
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regional Green River trail in this way, and it typically serves as maintenance access for them.
On some projects, the District allowed a limited degree of trail -related recreation within the levee
project area. They have stated that the Gunter levee project could achieve some level of
recreation and have referenced other projects in the watershed as examples.
Above is an example of a very schematic design developed for discussion purposes, showing
possible recreational access along the main trail and an adjacent secondary path/overlook area
on one section of the levee face. Staff expressed support for crediting the trail as well as some
selected areas that meet the TSO code requirements listed above toward off-site recreation
space which might result in 400 to 500 units worth of recreation space.
However, Staff questioned the utility and safety of inviting the public into sloped areas subject to
flooding and not highly visible from the trail as shown on the left side of the diagram below. It is
staff's determination that these types of spaces would not meet the off-site recreation criteria at
TMC 18.41.090, as an inaccessible natural/planted area.
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The property owner has suggested a cross section (shown below at 5) that creates a high
elevation flat area within the land that District is offering to purchase that would be utilized to
create recreation credits. However, this recreation space would be developed at the expense of
the habitat and flood storage objectives. Therefore, the design would not meet the District's
design objectives and would be unlikely to be permitted without additional off-site mitigation,
which the District is trying to avoid.
https://tukwilawa.sharepoint.com/sites/mayorsoffice/cc/Council Agenda Items/DCD/Gunter Levee/Gunter Levee Rec Space Memo.docx
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INFORMATIONAL MEMO
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5. Segale Conceptual Levee Cross Section with Recreation Area at top
Discussions between the City, the District and the property owner about the sale have reached
an impasse. Tukwila staff has suggested a compromise solution of a wider trail to alleviate
conflicts between bicycle commuters and recreational users along with one or more overlooks
containing seating or picnic tables. The County is reluctant to deviate from the standard of a 12 -
foot trail with 2 -foot shoulders (16 foot easement) because of implications to provide adequate
space for habitat and to ensure the flood improvement project can be self mitigating. The
standard trail design would result in less recreation area credit than the property owner desires.
Options:
1) Maintain current policy of granting off-site recreation space credit for all usable levee
areas (trail, overlooks, picnic areas) that meet the current TSO code requirements ; or
2) Lower the code requirement for off-site recreation space in the TSO Zone so that the
area generated by the standard trail and useable recreation space along the future levee
would accommodate off-site recreation credits supporting a specific number of future
housing units desired by the property owner; or
3) Eliminate the code requirement for off-site recreation space in the TSO Zone to remove
an impediment to the reconstruction of the Gunter levee. This would result in 75 square
feet of on-site recreation area for each future housing unit, the District constructed trail,
and whatever off-site space the property owner voluntarily constructs. The property
owner has indicated that it intends to install more recreation space than is already
required by City code, thus the off-site recreation space requirement is redundant.; or
4) Clarify for staff that planted areas on levee slopes which are not intended for human use
meet the intent of off-site recreation space so that we can calculate a recreation credit to
the property owner for future residential development; or
5) Clarify for staff that only recreation space owned, developed, and maintained by the
property owner or an entity affiliated with the housing developer should be counted as
off-site recreation space for future housing units.
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INFORMATIONAL MEMO
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In the near to mid-term Options 1 through 4 would all result in the same amount of recreation
space being developed, the levee trail, assuming that the property owner proceeded with the
sale.
• The property owner has said that Option 1 does not meet their needs and that is why
staff is bringing the issue to Council.
• Option 2 would be a compromise and the reduction in required off site recreation space
would need to be negotiated.
• Option 3 would likely be the most straightforward path to facilitating an agreement for the
property purchase and levee reconstruction as it removes the recreation space issue
from the property sale negotiation.
• Options 2 and 3 would each require amending the Zoning Code with a process that
requires a Planning Commission hearing and SEPA Determination.
FINANCIAL IMPACT
There is no financial impact to the City budget since District is offering to purchase the property
and is funding the Gunter levee project. However, if an agreement for the property purchase is
not reached in the near future the District could shift their funding to another project. This could
result in an increased danger of a flood event and additional areas within Tukwila being mapped
as floodplain, limiting their development potential.
RECOMMENDATION
Staff is seeking policy direction to enable negotiations for the Gunter Levee project to move
forward. Staff believes that option 3 is straight forward and recommends the City Council adopt
an ordinance to remove the offsite recreation space requirement. Council is being asked to
consider this item at the June 13, 2022 Committee of the Whole meeting. If an option requiring a
zoning code change is chosen staff asks that it be sent directly to Planning Commission rather
than returning to PCD Committee in order to expedite a resolution to this issue.
ATTACHMENTS
A. Tukwila 205 Certification Study Letter
B. Tukwila South Levee Transfer Request with Appendix A MOU
https://tukwilawa.sharepoint.com/sites/mayorsoffice/cc/Council Agenda Items/DCD/Gunter Levee/Gunter Levee Rec Space Memo.docx
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May 1,2019
City of Tukwila
Mayor's Office - David Cline, City Administrator
King County Flood Control District
Michelle Clark, Executive Director
516 3rd Avenue, Room 1200
Seattle, WA 98104
RE: Tukwila 205 — Certification Study
King County Flood District's 2019 Capital Budget - Proposed City Projects
Dear Ms. Clark:
Attachment A
Allan Ekberg, Mayor
The City of Tukwila is working with Northwest Hydraulics Consultants (NHC) to evaluate and certify the
Tukwila 205 Levee in accordance with Federal Emergency Management Agency (FEMA) requirements.
The 4.5 -mile long levee is located on the left bank of the Green River between Interstate 405 and South
196th Street and protects the highly developed Tukwila Urban Center. Work to date is comprised of a
Phase 1 and Phase 2 Accreditation report.
The Phase 1 report evaluated the levee conditions relative to Code of Federal Regulations Title 44,
Chapter I, Subchapter B, Part 65, Section 10 criteria on a project reach scale, to determine if the levee
could be certified in the existing condition. The Phase 1 report found that steep side slopes result in
significant lengths of levee failing to meet the required factor of safety for several geotechnical criteria.
FEMA requires that levees be certified in their entirety therefore the entire levee cannot be accredited in
its current condition.
The Phase 2 report took a detailed look at each segment identified in the Phase 1 report as not meeting
FEMA requirements. This included using site specific information, including additional geotechnical and
survey work, to further investigate and more accurately define the limits of the deficient segments. This
detailed work has shown that approximately 80% of the Tukwila 205 Levee cannot be certified in its
existing condition. The Phase 2 report also considered large scale improvement options for repair and
certifying the deficient levee segments, developed conceptual plans and initial cost estimates, and
proposed a prioritization for constructing large scale improvements.
The following list of ten prioritized projects was developed as a result of this certification effort. They are
the City of Tukwila's highest priority regarding flood risk throughout the City and are needed to certify
the Tukwila 205 Levee as providing 100 -year level of protection. The City of Tukwila is requesting that
each of these projects be included in the Flood Districts Capital Budget for construction within the next
10 years.
1. Gaco-Mitchell-Segale Levee from RM 15.41 to RM 15.90. Approximately 2,600' of levee
repair to address the highest calculated levee failure risks based on computed factor of
safety. This project should also seek to obtain additional property rights to allow for the levee
to be setback to reduce overall project costs, construction impacts, and to provide needed
habitat benefits.
Tukwila City Hall • 6200 Southce at r' Boulevard • Tukwila, WA 98188 • 206-433-18 'i • Website: Tukwila WA.gow
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Michelle Clark, SEPA Responsible Official
April 22, 2019
Page 2
2. S. 180th Bridge to Pedestrian Bridge from RM 14.33 to RM 14.75. Approximately 2,000' of
levee repair to address this high scour area and over steepened banks.
3. Christensen Rd. Levee from RM 13.40 to RM 13.60. Approximately 1,200' of levee repair to
address slope stability.
4. Ratolo Levee from RM 14.75 to RM 14.92. Approximately 1,000' of levee repair along S.
180th St. between the pedestrian bridge and Segale Floodwall to address a moderate to high
risk of slope failure.
5. Van Warden Levee from RM 12.77 to RM 12.98 adjacent to the Riverview Plaza Business
Park. Approximately 1,100' of levee repair to address a high risk of slope failure.
6. Christensen Rd. Levee from RM 13.85 to RM 14.32. Approximately 2,450' of levee repair to
address slope stability.
7. Segale-Green Levee from RM 15.10 to RM 15.41. Approximately 1,600' of levee repair for
moderate risk of slope failure. The upstream end point of this repair will tie into the Gaco-
Mitchell-Segale repair so the exact limits will need to be determined once this repair is
complete.
8. Gunter Levee from RM 15.90 to RM 16.70. Approximately 4,250' of levee repair to address
moderate risk of slope failure. The downstream project limit will tie into the Gaco-Mitchell-
Segale project.
9. Christensen Rd. Levee RM 12.56 to RM 12.67. Approximately 1,000' of levee repair to
address a low risk of slope failure.
10. Cross Levee from RM 16.70 to high ground tie in. Approximately 1,050' of levee repair to
address moderate freeboard and stability issues.
In closing, the City requests that the Flood District provide funding for the ten Tukwila 205 certifications
projects in the Flood District's 2019 Capital Budget. These projects are the City's highest priority and
will provide the Tukwila Urban Center with a 100 -year level of flood protection. Thank you for your
consideration of the City's flood control needs.
Sincerely,
Allan Ekberg
Mayor, City of Tukwil
Enclosures: Tukwila Levee Accreditation — Phase 2 Report
Phone: 206-433-1800 • Email: Mayor@TukwilaWA.gov • Website: TukwilaWA.gov
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SEGALE
CONMERCIAt' NOUSTRIAL AUR CULTURAL NATURAL RESOURCES
October 16, 2019
Michelle Clark, Executive Director
King County Flood Control District
516 3' Avenue, Room 1200
Seattle, WA 98104
RE: Tukwila South Levee Transfer Request
Dear Director Clark,
Attachment B
Through this letter, Segale Properties LLC (Segale) is formally requesting that the King County
Flood Control District (FCD) accept into their inventory, the Tukwila South Levee located on
the left bank of the Green River between River Mile 16.8 and 171.
This levee was originally proposed by Segale as an extension of the Tukwila 205 Levee and
was designed and constructed by Segale to meet all applicable US Army Corps of Engineers'
(USAGE) requirements. The City of Tukwila supported Segale in this effort and formally
submitted a Section 408 Levee Modification to the USACE in April 2009. This request was
denied because it was determined that it would require Congressional approval to change the
area that was protected under the original 205 program authorization. Since its completion in
2013, Segale has maintained the Tukwila South levee as a private levee.
Segale made a request to the King County Flood Control District (FCD) concerning the
possible transfer of the levee into the District's inventory. In response to this inquiry, Aspect
Consulting was hired by River and Floodplain Management Section (RFMS) staff to study,
inspect, and produce a report on the levee system's overall condition. The report concluded
that this levee, in general, meets the criteria for Levee Certification by FEMA and is eligible for
the PL 84-99 program by USACE. Additionally, Segale and FCD have agreed to some minor
conditions which are listed in a Memorandum of Understanding, attached as Appendix A of
this letter.
The p Memorandum of Understanding is enclosed for your convenience. RFMS staff
is in control of the report prepared by Aspect Consulting and can provide it upon request. All
RFMS noted field deficiencies have been corrected by Segale and all as -built and construction
records have been transmitted to RFMS staff for review and for their records. In summary,
the levee improvements constructed by Segale satisfy all the conditions and requirements for
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acceptance of the Tukwila South Levee into the FCD inventory as an FCD asset to be
maintained by the FCD in perpetuity.
The draft easement required to inspect, repair and upgrade the levee is enclosed for your
review. The easement will be executed and recorded upon the FCD accepting the Tukwila
South Levee as an asset to be maintained by the FCD
If you have any questions or require any additional information to evaluate this request, please
feel free to contact me at 206-575-2000.
Very truly yours,
SEGALE PROPERT,`/LLC
Mark A. Segale
President of Its Manag
Attachments: Easement documents
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Page 2 of 2
Appendix �
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October 15, 2019
Memorandum of Understanding between the King County Flood Control
District (FCD) and Segale Properties LLC [- /Seg@|e\
Gaco-Mitchell-Segale Levee Replacement CIP related items for Right -of -Way (ROW) to
support the pject:
. Segale agrees to provide at fair market value, additional ROW or easements (maybe
only the 5-15 ft. wide grassy area between existing fence and the parking lot strip)
between the levee and the Segale warehouse (parcel number 352304-9115), provided
it doesn't affect/impact the current Segale business operations.
Z. Segale agrees to provide at fair market value, additional ROW or easement at two levee
transition areas upstream (u/s) and downstream (d/s) of Gaco and Mitchell properties
where the potential setback levee is planned and needs to be transitioned to the u/s and
d/s levee sections.
3. FCD agrees to provide at fair market value, any surplus ROW or easement to Segale,
where the surplus ROW or easement is adjacent to Segale ownership, between RM
15.88 and RM 167.
4. Segale agrees to provide at fair market value, additional ROW or easement between the
existing easement and 125 feet landward of the OHWM for the levee section between
RM 15.88 and RM 167 for the FCD to construct a levee wall to contain the 500 -year
flood. It is understood the additional ROW or easement granted by Segale will be the
minimal amount needed to complete the levee wall.
5. Easement along the Segale stormwater pond (RM 17.2 — 173): Segale will provide
additional easement area between Segale's pond and the river. The additional easement
is for the FCD to be able to maintain the entire levee prism on the river side and on the
pond side without encroaching into private property during potential future repairs.
Segale has provided an exhibit showing the location of the existing City of Tukwila levee
easement with the requested additional easement area along Segale's stormwater
pond. In addition, Segale revised the easement to match the asbuilt levee at the S.
200' bridge (River and Floodplain Management Section has been provided drawings
showing both areas).
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6. The new levee easement along the west border of the Segale mitigation pject (RM
16.85-17.0): The landward levee slope is retrofitted to meet the slope requirements as
requested by United States Army Corps of Engineers (USACE). The current easement
language shows the easement border at the top of the slope, on the landward side.
Segale will add language in the levee easement for two potential future conditions:
• If the area is filled to the top of the levee, the easement will stay as is.
• If not filled at the time of development, the easement will extend to the
landward toe plus 10 feet of inspection area.
Segale has provided a redline to the existing City of Tukwila easement which includes
the above language and will be included in the levee easement accepted by FCD.
7. U/S terminus of the Tukwila South Levee has jersey barriers at 5. 204th St. At the time
of transfer, the FCD will build a gate and Segale would remove the jersey barriers. Both
the FCD and Segale will have keys to access the levee top.
8. King County Drainage District #2 owns the property which contains Johnson Creek and
its outfall to the Green River. Johnson Creek outfall is deemed not fish passable by
WRIA at this time. Segale indicated that during the time of construction, Washington
Department of Fish and Wildlife approved the design of the outfall culvert and the gate.
The gate is designed to stay open and be fish passable until the water in the Green
River gets too high, at which time the gate closes for flood protection.
Segale will not oppose modification of this outfall if needed in the future, provided after
review of final plans there is no impact to Segale's existing, adjacent stormwater pond
and properties.
9. Gunter Cut-off Levee access or by-pass around the temporary jersey barriers. Segale
has built a temporary gravel bypass road around the jersey barriers which is acceptable
to the King County River and Floodplain and Management Section. The by-pass will
remain in place until the future development allows for removal of the utility crossing
and/or buries the utility.
10. Segale stormwater pond (RM 17.2- 17.3) outfall control structure: The FCD is waiting
for an opinion from the USACE if this structure would be acceptable within the levee
prism in the context of PL 84-99 eligibility. If not, Segale agrees to work with the FCD
to resolve this issue.
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