HomeMy WebLinkAboutCDN 2019-08-13 Item 2 - Handout Distributed at Meeting - Shoreline Master Program UpdateShoreline ter Program
Page 43 of the packet (Page 26 al S MP strike/mtt underline version)
4.5 Conclusions
Like many rivers in the Puget Sound region, the course and dynamics of the
Green/Duwamish River has -have changed significantly as a result of development and
alteration of its watershed over the past century or so. Characteristic of many cities in the
region, Tukwila has grown and become highly urbanized. Continued growth is anticipated
and the City is planning for that growth. To a significant degree, the City has envisioned
and maintained a development pattern that preserved public access to the Green River and
assured setbacks of new buildings from the shoreline. Issues of concern today are focused
on reconstructing existing levees and revetments to protect existing development from
flood hazards and restore habitat, an effort that will take place over a number of years in
coordination with the King County Flood Control Zone District, King County and state and
federal agencies. There are many opportunities for conservation and restoration actions in the
City to restore or replace habitat while managing natural hazard areas.
Page 50 of the i)acket (Page 47 of SMP strike/out underline version)
7.2 Key Findings of the Shoreline Inventory / Characterization Report and
Restoration Plan
This section summarizes findings from the Inventory and Characterization Report and
Restoration Plan elements of the SMP update (Appendices A and B). These findings inform
the goals, policies, regulations, and the development and application of environment
designations. In this context, the key findings can be summarized as follows:
• The Green/Duwamish River throughout Tukwila is a critical habitat resource for
salmonids and other species. Adult salmon heading upstream to spawn require cool
water; and juveniles heading downstream require food and refuge from high flows;
particularly in tThe Transition Zone, portion of the river whichthat-extends from river
mile 10 upstream from the Interstate 5 bridgodownstream through the northern City
limits (see Map 2), where juvenile salmon adjust from fresh to salt water habitat
(osmoregulate), is of critical importance because of significant habitat losses over the
years. Additionally, Tthe river provides migratory habitat for numerous fish species, as
well as riparian habitat for a variety of wildlife.
3. Page 54, 5 an(I 56 of tile paailiet
(Pg51 2, and 53 S strike/out isrideriine version)
Replace 2.5:1 with 3:1
Table 31. Summary of Buffer Widths for Land Use Zones and Shoreline Ecological
Conditions
Area
Characteristics
Environment
BufferModification
MIC/H &
Fresh/Salt Water
High Intensity
100'
The Director may reduce the standard
MIC/L zoned
property from
Transition Zone,
Lower flooding
buffer on a case -by -case basis by up to
50% upon construction of the following
North City
risk, Less than 20'
cross section:
Limits to
difference from
- 1. Reslope bank from OHWM (not toe)
EMWS
OHWM to top of
to be no steeper than 3:1, using
Bridge, and
bank, tidal
bioengineering techniques
North
Potential
influence
- 2. Minimum 20' buffer landward from
top of bank
Annexation
Area
- 3. Bank and remaining buffer to be
planted with native species with high
habitat value
Comment: Maximum slope is reduced
due to measurement from OHWM and to
recognize location in the Transition Zone
where pronounced tidal influence makes
work below OHWM difficult.
Any buffer reduction proposal must
demonstrate to the satisfaction of the
Director that it will not result in direct,
indirect or long-term adverse impacts to
the river. In all cases a buffer
enhancement plan must also be approved
and implemented as a condition of the
reduction. The plan must include using a
variety of native vegetation that improves
the functional attributes of the buffer and
provides additional protection for the
shoreline ecological functions.
LDR zoned
Moderate flooding
Shoreline
Distance
Removal of invasive species and
property w/o
risk, Less than 25'
Residential
required
replanting with native species of high
levees from
difference from
to set
habitat value voluntary unless triggered
EMWS to I-
OHWM to top of
back
by requirement for a Shoreline
405
bank, tidal
influence on
northern section
slope
from toe
at 2 5.1
. .
plus 20'
setback,
Min. 50'
width
Substantial Development permit.
2
Area
Characteristics
Environment
Buffer
Modification
LDR zoned
property with
levees from
EMWS to
1-405
Moderate flooding
risk, Less than 25'
difference from
OHWM to top of
bank, tidal influence
on northern section
Shoreline
Residential
125'
Upon reconstruction of levee in
accordance with City levee standards, the
Director may reduce the buffer to actual
width required.
Comment: This applies to City -owned
property at Fort Dent.
Commercially
zoned property
from 42nd
Ave S. Bridge
to
1-405
Moderate flooding
risk, Less than 25'
difference from
OHWM to top of
bank
Urban
Conservancy
100'
The Director may reduce the standard
buffer on a case -by -case basis by up to
50% upon -construction of the following
cross section:
- 1. Reslope bank from toe to be no
steeper than 2.5:1, using
bioengineering techniques
- 2. Minimum 20' buffer landward from
top of bank
- 3. Bank and remaining buffer to be
planted with native species with high
habitat value
Any buffer reduction proposal must
demonstrate to the satisfaction of the
Director that it will not result in direct,
indirect or long-term adverse impacts to
shoreline ecological functions. In all
cases a buffer enhancement plan must
also be approved and implemented as a
condition of the reduction. The plan must
include using a variety of native
vegetation that improves the functional
attributes of the buffer and provides
additional protection for the shoreline
ecological functions.
West River
bank from
1-405 to South
City Limit,
Tukwila 205
Levee and
South
Annexation
Area
High flooding risk,
Federally certified
and County levee,
large water level
fluctuations
Urban
Conservancy
125'
Upon construction or reconstruction of
levee in accordance with City levee
standards the Director may reduce the
buffer to the actual width required. In no
case shall the buffer be less than 50 feet.
3
Area
Characteristics
Environment
Buffer
Modification
East River
bank without
levee from I-
405 south to
City Limits
Moderate flooding
risk, 20 to 25'
difference from
OHWM to top of
bank, Moderate
slumping risk, large
water level
fluctuations
Urban
Conservancy
100'
The Director may reduce the standard
buffer on a case -by -case basis by up to
50% upon construction of the following
cross section:
- 1. Reslope bank from toe to be no
steeper than 2.5:1, using
bioengineering techniques
- 2. Minimum 20' buffer landward from
top of bank
- 3. Bank and remaining buffer to be
planted with native species with high
habitat value
Any buffer reduction proposal must
demonstrate to the satisfaction of the
Director that it will not result in direct,
indirect or long-term adverse impacts to
shoreline ecological functions. In all cases
a buffer enhancement plan must also be
approved and implemented as a condition
of the reduction. The plan must include
using a variety of native vegetation that
improves the functional attributes of the
buffer and provides additional protection
for the shoreline ecological functions.
East River
bank with
levee from I-
405 to South
City Limit
Moderate flooding
risk, 20 to 25'
difference from
OHWM to top of
bank, Moderate
slumping risk, large
water level
fluctuations
Urban
Conservancy
125'
Upon reconstruction of levee in
accordance with City levee standards the
Director may reduce the buffer to the
actual width required for the levee. In no
case shall the buffer be less than 50 feet.
Any shoreline
environment
where street or
road runs
parallel to the
river through
the buffer
End buffer on river side of existing
improved street or roadway.
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4. Page 38 of the pagitet (Page 64-67 cif Sh4P strike/out widerline version)
Replace 2.5:1 with 3:1
Section 7 Urban Conservancy Environment
C. Establishment of River Buffers
The Urban Conservancy environment will have two different buffers, depending on the location
along the river and whether or not the shoreline has a flood control levee. The purpose of Urban
Conservancy River Buffers is to:
• Protect existing and restore degraded ecological functions of the open space, floodplain
and other sensitive lands in the developed urban settings;
• Ensure no net loss of shoreline function when new development or re -development is
proposed;
• Provide opportunities for restoration and public access;
• Allow for adequate flood and channel management to ensure protection of property, while
accommodating shoreline habitat enhancement and promoting restoration of the natural
character of the shoreline environment, wherever possible;
• Avoid the need for new shoreline armoring; and
• Protect existing and new development from high river flows.
Buffer in Non -Levee Areas:
A buffer width of 100 feet is established for the Urban Conservancy Environment for all non-
residential areas without levees. This buffer width is consistent with that established by the City's
Sensitive Areas Ordinance for Type 2 streams that support salmonid use, which is based on Best
Available Science. In addition, as noted above, looking at the slope geometry and the difference
in height between the ordinary high water mark and the 100-year flood elevation for these areas,
it was found that a 100-foot setback distance is required to accommodate the slopes needed for
bank stability.
The buffer width of 100 feet allows enough room to reconfigure the riverbank to achieve a slope
of 2.5:1, the "angle of repose" or the maximum angle of a stable slope and allow for some
restoration and improvement of shoreline function through the installation of native plants and
other habitat features. The actual amount of area needed to achieve a 2.5:1 slope may be less than
100 feet, depending on the character of the riverbank and can only be determined on a site -by -site
basis.
As an alternative to the 100-foot buffer, a property owner may re -slope the riverbank to be no
steeper than 2.5:1, provide a 20-foot setback from the top of the new slope and vegetate both the
riverbank and the 20-foot setback area in accordance with the standards in the Vegetation
Protection and Landscaping Section. Any buffer reduction proposal must demonstrate to the
satisfaction of the Director that it will not result in direct, indirect or long-term adverse impacts to
shoreline ecosystem functions. In all cases a buffer enhancement plan must also be approved and
implemented as a condition of the reduction. The plan must include removal of invasive plants,
and plantings using a variety of native vegetation that improves the functional attributes of the
5
buffer and provides additional protection for the watercourse functions. In no case shall the buffer
be less than 50 feet.
In areas of the river where this condition currently exists or where the property owner has
constructed these improvements, the buffer width will be the actual distance as measured from the
ordinary high water mark to the top of the bank plus 20 feet.
The shoreline jurisdiction and buffers for the Urban Conservancy Environment are depicted in the
schematic in Figures 4 and 5 below.
Allow room to
reconfigure
river bank to
2.5:1 slope
rz 200'
Urban Conservancy Environment
1 00'
>I
er
Ordinary High Water Mark
Rivi
Figure 4. Schematic of Shoreline Jurisdiction and Buffers for the Urban Conservancy
Environment in Areas without Levees
Buffer in Levee Areas:
For properties located behind the Army Corps of Engineers (ACOE) Certified 205 levee and
County constructed levees, the buffer will extend 125 feet landward from the ordinary high water
mark, determined at the time of development or redevelopment of the site or when levee
replacement or repair is programmed. This buffer width is the maximum needed to reconfigure
the riverbank to the minimum levee profile and to achieve an overall slope of 2.5:1, the "angle of
repose" or the maximum angle of a stable slope. The establishment of the 2.5:1 slope along the
Corps certified 205 levee in the Tukwila Urban Center will allow for incorporating a mid -slope
bench that can be planted with vegetation to improve river habitat. The mid -slope bench also will
allow access for maintenance equipment, when needed. An easement to allow access for levee
inspection is required on the landward side of the levee at the toe.
6
200'
Urban Conservancy Environment
k 125' A
Allow room
forLevee
repairor Buffer
replacement
z
Ordinary High Water Mark
RverI
Figure 5. Schematic of Shoreline Jurisdiction and Buffers for the
Urban Conservancy Environment in Areas with Levees
As an alternative to the 125 foot buffer for leveed areas, a property owner may construct levee or
riverbank improvements that meet the Army Corps of Engineers, King County Flood Control
District, and City of Tukwila minimum levee standards. These standards at a minimum shall
include an overall slope no steeper than 2.5:1 from the toe of the levee to the riverward edge of the
crown, 16-foot access across the top of the levee, a 2:1 back slope, and an additional no -build area
measured from the landward toe for inspection and repairs. In instances where an existing building
that has not lost its nonconforming status prevents achieving an overall slope of 2.5:1 the slope
should be as close to 2.5:1 as possible.
A floodwall is not the preferred back slope profile for a levee but may be substituted for all or a
portion of the back slope where necessary to avoid encroachment or damage to a structure legally
constructed prior to the date of adoption of this Master Program which has not lost its
nonconforming status and to preserve access needed for building functionality. The floodwall
shall be designed to provide 15--foot clearance between the levee and the building or to preserve
access needed for building functionality while meeting all engineering safety standards. A
floodwall may also be used where necessary to avoid encroachment on a railroad easement or to
provide area for waterward habitat restoration.
In areas of the river where the property owner or a government agency has constructed a levee
with an overall waterward slope of 2.5:1 or flatter, the buffer will be reduced to the actual distance
as measured from the ordinary high water mark to the landward toe of the levee or face of a
floodwall, plus 15 feet. In the event that the owner provides the City and/or applicable agency
with a levee maintenance easement measured landward from the landward toe of the levee or levee
wall (which easement prohibits the construction of any structures and allows the City and/or
applicable agency to access the area to inspect the levee), then the buffer shall be reduced to the
landward toe of the levee, or landward edge of the levee floodwall, as the case may be.
7
In cases where fill is placed along the back slope of the levee, the shoreline buffer may be further
reduced to the point where the ground plane intersects the back slope. The area between the
landward edge of the buffer and a point 15 feet landward of the underground levee toe shall be
covered by an easement prohibiting the construction of any structures and allowing the City and/or
applicable agency to access the area to inspect the levee and/or floodwall and make any necessary
repairs. See Figure 6 below.
Buffer that could
Be Replaced
by Easements
New Ground
Plane,...._
Fill
10'
Access/
Inspection
Buffer Reduction
Landward
Levee Toe
2*
Proposed Levee
18' Top Width
1
Buffer Reduction with Backfill Option
Not To Scale
Figure 6. Schematic of Buffer Reduction Through
Placement of Fill on Levee Back Slope
Buffer in Non -Levee Areas:
A buffer width of 100 feet is established for the Urban Conservancy Environment for all non-
residential areas without levees. This buffer width is consistent with that established by the City's
Sensitive Areas Ordinance for Type 2 streams that support salmonid use, which is based on Best
Available Science. In addition, as noted above, looking at the slope geometry and the difference
in height between the ordinary high water mark and the 100-year flood elevation for these areas,
it was found that a 100-foot setback distance is required to accommodate the slopes needed for
bank stability.
The buffer width of 100 feet allows enough room to reconfigure the riverbank to achieve a slope
of 2.5:1, the "angle of repose" or the maximum angle of a stable slope and allow for some
restoration and improvement of shoreline function through the installation of native plants and
other habitat features. The actual amount of area needed to achieve a 2.5:1 slope may be less than
100 feet, depending on the character of the riverbank and can only be determined on a site -by -site
basis.
As an alternative to the 100-foot buffer, a property owner may re -slope the riverbank to be no
8
steeper than 2.5:1, provide a 20-foot setback from the top of the new slope and vegetate both the
riverbank and the 20-foot setback area in accordance with the standards in the Vegetation
Protection and Landscaping Section. Any buffer reduction proposal must demonstrate to the
satisfaction of the Director that it will not result in direct, indirect or long-term adverse impacts to
shoreline ecosystem functions. In all cases a buffer enhancement plan must also be approved and
implemented as a condition of the reduction. The plan must include removal of invasive plants,
and plantings using a variety of native vegetation that improves the functional attributes of the
buffer and provides additional protection for the watercourse functions. In no case shall the buffer
be less than 50 feet.
In areas of the river where this condition currently exists or where the property owner has
constructed these improvements, the buffer width will be the actual distance as measured from the
ordinary high water mark to the top of the bank plus 20 feet.
11 ZI 1 CO E
1. Page 97 and 98 of the packet (Page 10 and 11 of P(' Draft 18.44 Strikeout)
Replace 2,5:1 with 3:1
18.44.040 Shoreline Buffers
Buffer widths. The following shoreline buffer widths apply in shoreline jurisdiction.
Environment
Buffer width (1)(2) Modification
Shoreline Residential
50 feet OR the area needed to
achieve a slope no steeper than
2.5:1, measured from the toe of the
bank to the top of the bank, plus 20
linear feet measured from the top of
the bank landward, whichever is
greater
(3)
Urban Areas without 100 feet (4)
Conservancy levees
Areas with levees 125 feet (5)
High Intensity
100 feet (4)
Aquatic Not Applicable
(1) Unless otherwise noted, all buffers are measured landward from the OHWM.
9
(2) In any shoreline environment where an existing improved street or road runs parallel to the
river through the buffer, the buffer ends on the river side of the edge of the improvedright-
of-way.
Removal of invasive species and replanting with native species of high habitat value
voluntary unless triggered by requirement for a Shoreline Substantial Development permit.
(4) The Director may reduce the standard buffer on a caSe-by-casebasis byupto 50%Vpon
construction nfthe following cross section:
(a) Rea/oPe bank from toe to be no steeper than 2.51 in the Urban Conservancy
Environment grMas|ope bank from OHVVyW (not toe) to be no steeper than 3:1 in the
High Intensity EnVironrnent, using bioengineering techniques
(b) Minimum 2O-fOotbuffer landward from top 0fbank.
(o) Bank and remaining buffer to be planted with native species with high habitat value.
Maximum slope iareduced due to measurement from OHVVW1 and torecognize |0uahoM in
the Transition Zone where pronounced tidal influence makes work below OHVVM difficult.
Any buffer reduction proposal must demonstrate to the satisfaction of the Director that it will
not result in dineot, indirect or long-term adverse |rnp2ctS to the river. In all cases a buffer
enhancement plan must also be approved and implemented aoo condition of the reduction.
The p|oO must include using avorioty ofnative vegetation that improves the functional
attributes of the buffer and provides additional protection for the shoreline ecological
functions.
CB (B Upon reconstructionoflevee tothe levee standards ofthis chapter,the Director may reduce
the buffer to actual width required for the levee. If fill is placed along the back slope of a new
levee, the buffer may be reduced to the point vvhena the ground plane intersects the booh
slope of the levee. If the property owner provides levee maintenance easement landward
from the landward toe of the levee or levee vvm|| which: 1) meets the width required by the
agency providing maintenance; 2>prohibits the construction ofany structures; and 8\allows
the City toaccess the area toinspect the levee and make any necessary repairs, then that
area may baoutside ofthe shoreline buffer and allow incidental uses such aeparking.
10
Page 109 of the ptickei (Page 19 of PC Draft 18.44 Strikeout)
Keep the phrase "beyond what may otherwise be required"
3. Height Restrictions. Except for bridges; approved above ground utility structures,
and water -dependent uses and their structures, to preserve visual access to the shoreline
and avoid massing of tall buildings within the shoreline jurisdiction, the maximum height
for structures shall be as follows:
a. 15 feet where located within the River Buffer;
b. 6545 feet between the outside landward edge of the River Buffer and
200 feet of the OHWM.
c.
5 feet above average grade level on shorelines of the State that
will obstruct the view of a substantial number of residences on areas adjoining such
shorelines. For any building that is proposed to be greater than 35 feet in height in the
shoreline jurisdiction; the development proponent must demonstrate the proposed
building will not block the views of a substantial number of residences, The Director may
approve a 15 foot % increase in height for structures within the shoreline jurisdiction if the
project proponent provides additional restoration andlor enhancement of the entire
shoreline buffer, ed t-m-the#ye43e-FePed including, but not limited to,
paved areas no longer in use on the property in accordance with the standards of TMC
Section 18.44.! .te060, "Vegetation Protection and Landscaping." If the required buffer
has already been restored, the project proponent may provide a 20% wider buffer, planted
in accordance With TMC Section 18.44.060 ;Vegetation Protection and Landscaping,"
and/or enhanced in order to obtain the 15 % foot increase in height.
TMC Section 18_41.080, "Vegetation Protection and Landscaping."
3. Page 117 of the packet (Page 24 of PC Draft 18.44 Strikeout)
K. Marinas, Boat Yards, Dry Docks, Boat Launches, Piers, Docks and Other Over -
water Structures.
1. General Requirements.
a. A dock may be allowed when the applicant has demonstrated a need
to the satisfaction of the Director of Community Development for moorage and that the
following alternatives have been investigated and are not available or feasible:
(1) commercial or marina moorage;
(2) floating moorage buoys;
(3) joint use moorage pier/dock.
11
4 ['age 124 of the packet (Page 28 of PC Draft 18.44 Strikeout)
Consider deleting "Trees interfere with the access and passage on public trails" or add
who makes this decision.
Criteria for Shoreline Tree Removal. A Type 2 Shoreline Tree Removal and Vegetation
Clearing Permit shall only be approved if the proposal complies with the following criteria as
applicable:
a. The site is undergoing development or redevelopment;
b. Tree poses a risk to structures;
c. There is imminent potential for root or canopy interference with utilities;
d. Trees interfere with the access and passage on public trails;
e. Tree condition and health is poor, the City may require an evaluation by an
International Society of Arborists (ISA) certified arborist;
f. Trees present an imminent hazard to the public. If the hazard is not readily
apparent, the City may require an evaluation by an International Society of Arborists (ISA)
certified arborist; and
g. The proposal complies with tree retention, replacement, maintenance and
monitoring requirements of this Chapter.
5, Page 127 of the packet (Page 31 of PC Draft 18.44 Strikeout)
Clarify that exemption from restoration of properties landward of publicly maintained
levees is only for the leveed portion, any remaining buffer area is subject to replanting
requirements.
c. On properties located behindlandward of publicly maintained levees, an applicant is not
required to remove invasive vegetation or plant native vegetation within the buffer.
On properties located landward of publicly maintained levees, an applicant is not required to remove
invasive vegetation or plant native vegetation on the levees, however the remaining buffer landward of
the levee shall be improved and invasive vegetation removed with native vegetation planted.
12
6. Page 166 of tlik packet (Page 55 of the PC Draft 18.44 Strikeout)
Add phrase "when non -conforming use ceases to exist" after "the two-year period".
Non -conforming Uses
be. If any such non -conforming use ceases for any reason for a period of more than 24 consecutive
months, the nen-conforming rights shall expire td any subsequent use shall conform to the
regulations specified by in this chapter for the shoreline environment in which such use is located,
unless re-establis ent of the use is authorized through a Shoreline Conditional Use Permit, which
must be applied for within the twoivear period. Wateindependent uses should not be considered
discontinued when they are inactive clue to dormancy, or where the use is typically seasonal. Upon
request of the owner: prior to the end of the 24 consecutive months and upon reasonable cause
shown: the City Co cil may grant an extension of time beyond the 24 consecutive months using
the criteria set forth in TNIC Section 18.11.1030.EG.1 18 44.110.G.4.
7. Page 167 of the packet (Page 5( of th» PC Draft 18.44 Strikeout)
Delete the proposed language and limit alterations to 50% of the value of the structure.
Non -conforming Structures
(2) If the cture is located on a property that has no reasonable development potential
outside the shoreline buffer, there shall be no limit on the cost of alterations_ If the structure is
located on a property that has reasonable development potential outside the shoreline buffer.
Ithe cost of the alterations may not exceed an aggregate cost of50% of the value of the building
or stnicture in any 3-year period based upon its most recent assessment, unless the amount over
50°C, is used to make the building or structure more conforming, or is used to restore to a safe
condition any portion of a building or structure declared unsafe by a proper aut14rity
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