HomeMy WebLinkAboutCOW 2009-11-23 Item 4I.1 - Shoreline Master Program - Attachment A.10: Environmentally Sensitive Areas within the Shoreline Jurisdiction10. ENVIRONMENTALLY SENSITIVE AREAS WITHIN THE
SHORELINE JURISDICTION.
10.1 Purpose
A. The Growth Management Act (RCW 36.70A) requires protection of critical areas
(sensitive areas), defined as wetlands, watercourses, frequently flooded areas,
geologically hazardous areas, critical aquifer recharge areas, fish and wildlife
conservation areas, and abandoned mine areas.
B. The purpose of protecting environmentally sensitive areas within the shoreline
jurisdiction is to:
1. Minimize developmental impacts on the natural functions and values of these
areas.
2. Protect quantity and quality of water resources.
3. Minimize turbidity and pollution of wetlands and fish bearing waters and
maintain wildlife habitat.
4. Prevent erosion and the loss of slope and soil stability caused by the removal
of trees, shrubs, and root systems of vegetative cover.
5. Protect the public against avoidable losses, public emergency rescue and relief
operations cost, and subsidy cost of public mitigation from landslide,
subsidence, erosion and flooding.
6. Protect the community's aesthetic resources and distinctive features of natural
lands and wooded hillsides.
7. Balance the private rights of individual property owners with the preservation
of environmentally sensitive areas.
8. Prevent the loss of wetland and watercourse function and acreage, and strive
for a gain over present conditions.
9. Give special consideration to conservation or protection measures necessary
to protect or enhance anadromous fisheries.
10. Incorporate the use of best available science in the regulation and protection
of sensitive areas as required by the state Growth Management Act, according
to WAC 365- 195 -900 through 365 -195 -925 and WAC 365 -190 -080.
C. The goal of these sensitive area regulations is to achieve no net loss of wetland,
watercourse, or fish and wildlife conservation area or their functions.
10.2 Applicability, Maps and Inventories
A. Sensitive areas located in the shoreline jurisdiction will be governed by the Shoreline
Management Program and not the City's Sensitive Areas Ordinance. However, the level
of protection for the critical areas shall be equal to that provided in the Sensitive Areas
section of the Zoning Code (TMC18.45).
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B. Sensitive areas currently identified in the shoreline jurisdiction are discussed in the
Shoreline Inventory and Characterization Report, which forms part of this Shoreline
Management Program. The locations are mapped on the Sensitive Areas in the
Shoreline Jurisdiction Map Map 65. This map is based on assessment of current
conditions and review of the best available information. However, additional sensitive
areas may exist within the shoreline jurisdiction and the boundaries of the sensitive areas
shown are not exact. It is the responsibility of the property owner to determine the
presence of sensitive areas on the property and to verify the boundaries in the field.
Sensitive area provisions for abandoned mine areas do not apply as none of these areas is
located in the shoreline jurisdiction.
C. Frequently flooded areas and areas of seismic instability will be governed by the
Flood Zone Management Code (TMC 16.52) and the Washington State Building Code.
10.3 Best Available Science
Policies, regulations and decisions concerning sensitive areas shall rely on Best Available
Science to protect their functions and values. Special consideration must be given to the
conservation or protection measures necessary to preserve or enhance anadromous fish
and their habitats. Nonscientific information may supplement scientific information, but
is not an adequate substitution for valid and available scientific information.
10.4 Sensitive Area Studies
An applicant for a development proposal that may include a sensitive area and/or its
buffer shall submit those studies as required by the City and specified below to
adequately identify and evaluate the sensitive area and its buffers.
A. General Requirements
1. A required sensitive areas study shall be prepared by a person with experience
and training in the scientific discipline appropriate for the relevant sensitive
area. A qualified professional must have obtained a B.S. or B.A. or equivalent
degree in ecology or related science, engineering, environmental studies,
fisheries, geotechnical or related field, and at least two years of related work
experience.
2. The sensitive areas study shall use scientifically valid methods and studies in
the analysis of sensitive area data and shall use field reconnaissance and
reference the source of science used. The sensitive area study shall evaluate
the proposal and all probable impacts to sensitive areas.
3. It is intended that sensitive areas studies and information be utilized by
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applicants in preparation of their proposals and therefore shall be undertaken
early in the design stages of a project.
B. Wetland, Watercourse and Fish and Wildlife Conservation Area Sensitive Area
Studies
At a minimum, the sensitive area study shall contain the following infonuation, as
applicable:
1. The name and contact information of the applicant, a description of the
proposal, and identification of the permit requested;
2. A copy of the site plan for the development proposal showing: sensitive areas
and buffers and the development proposal with dimensions; clearing limits;
proposed storm water management plan; and mitigation plan for impacts due
to drainage alterations;
3. The dates, names and qualifications of the persons preparing the study and
documentation of any fieldwork performed on the site;
4. Identification and characterization of all sensitive areas, water bodies, and
buffers adjacent to the proposed project area or potentially impacted by the
proposed project;
5. A statement specifying the accuracy of the study and assumptions used in the
study;
6. Deter nination of the degree of impact and risk from the proposal both on the
site and on adjacent properties;
7. An assessment of the probable cumulative impacts to sensitive areas, their
buffers and other properties resulting from the proposal;
8. A description of reasonable efforts made to apply mitigation sequencing to
avoid, minimize and mitigate impacts to sensitive areas;
9. Plans for adequate mitigation to offset any impacts;
10. Recommendations for maintenance, short-term and long -term monitoring,
contingency plans and bonding measures; and
11. Any technical information required by the director to assist in determining
compliance.
C. Geotechnical Studies
1. A geotechnical study appropriate both to the site conditions and the proposed
development shall be required for development in Class 2, Class 3, and Class
4 Areas.
2. All studies shall include at a minimum a site evaluation, review of available
information regarding the site and a surface reconnaissance of the site and
adjacent areas. For Class 2 areas, subsurface exploration of site conditions is
at the discretion of the geotechnical consultant. In addition, for Class 3 and
Class 4 Areas, the study shall include a feasibility analysis for the use of
infiltration on -site and a subsurface exploration of soils and hydrology
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conditions. Detailed slope stability analysis shall be done if the geotechnical
engineer recommends it in Class 3 areas, and must be done in Class 4 areas.
3. Applicants shall retain a geotechnical engineer to prepare the reports and
evaluations required in this subsection. The geotechnical report and completed
site evaluation checklist shall be prepared in accordance with generally
accepted geotechnical practices, under the supervision of and signed and
stamped by the geotechnical engineer. The report shall be prepared in
consultation with the appropriate City department. Where appropriate, a
geologist must be included as part of the geotechnical consulting team. The
report shall make specific recommendations concerning development of the
site.
4. The opinions and recommendations contained in the report shall be supported
by field observations and, where appropriate or applicable, by literature
review conducted by the geotechnical engineer which shall include
appropriate explorations, such as borings or test pits, and an analysis of soil
characteristics conducted by or under the supervision of the engineer in
accordance with standards of the American Society of Testing and Materials
or other applicable standards. If the evaluation involves geologic evaluations
or interpretations, the report shall be reviewed and approved by a geotechnical
engineer.
D. Modifications or Waivers to Sensitive Area Study Requirements
1. The Director may limit the required geographic area of the sensitive area
study as appropriate if:
a. The applicant, with assistance from the city, cannot obtain permission
to access properties adjacent to the project area; or
b. The proposed activity will affect only a limited part of the site.
2. The Director may allow modifications to the required contents of the study
where, in the judgment of a qualified professional, more or less information is
required to adequately address the potential sensitive area impacts and
required mitigation.
3. If there is written agreement between the Director and the applicant
concerning the sensitive area classification and type, the Director may waive
the requirement for sensitive area studies provided that no adverse impacts to
sensitive areas or buffers will result. There must be substantial evidence that
the sensitive areas delineation and classification are correct, that there will be
no detrimental impact to the sensitive areas or buffers, and that the goals,
purposes, objectives and requirements of the Shoreline Management Program
will be followed.
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10.5 Procedures
When an applicant submits an application for any building permit, subdivision, short
subdivision or any other land use review that approves a use, development or future
construction, the location and dimensions of all sensitive areas and buffers on the site
shall be indicated on the plans submitted. When a sensitive area is identified, the
following procedures apply.
A. The applicant shall submit the relevant sensitive area study as required by this
chapter.
B. The Department of Community Development will review the information submitted
in the sensitive area studies to verify the information, confirm the nature and type of the
sensitive area, and ensure the study is consistent with the Shoreline Master Program. At
the discretion of the Director, sensitive area studies may undergo peer review, at the
expense of the applicant.
C. Denial of use or development: A use or development will be denied if the Director
determines that the applicant cannot ensure that potential dangers and costs to future
inhabitants of the development, adjacent properties, and Tukwila are minimized and
mitigated to an acceptable level.
D. Preconstruction meeting: The applicant, specialist(s) of record, contractor, and
department representatives will be required to attend pre construction meetings prior to
any work on the site.
E. Construction monitoring: The specialist(s) of record shall be retained to monitor the
site during construction.
F. On -site Identification: The Director may require the boundary between a sensitive
area and its buffer or between the buffer and the development and any development or
use to be permanently identified with fencing, or with a wood or metal sign with treated
wood, concrete or metal posts. Size will be determined at the time of permitting, and
wording shall be as follows: "Protection of this natural area is in your care.
Do not alter or disturb. Please call the City of Tukwila (206- 431 -3670) for more
information."
10.6 Wetland Determinations and Classifications
A. Wetlands and their boundaries are established by using the Washington State Wetland
and Delineation Manual, as required by RCW 36.70A.175 (Ecology Publication #96 -94)
and consistent with the 1987 Corps of Engineers Wetland Delineation Manual.
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B. Wetland determinations shall be made by a qualified professional (certified Wetland
Scientist or non certified with at least 2 years of full -time work experience as a wetland
professional).
C. Wetland areas within the City of Tukwila have certain characteristics, functions and
values and have been influenced by urbanization and related disturbances. Wetland
functions include, but are not limited to the following: improving water quality;
maintaining hydrologic functions (reducing peak flows, decreasing erosion,
groundwater); and providing habitat for plants, mammals, fish, birds, and amphibians.
Wetland functions shall be evaluated using Washington State Functional Assessment
Method_, egu_ alent
-L"
D. Wetlands shall be designated in accordance with the Washington State Wetlands
Rating System (Washington Department of Ecology. August 2004. Publication #93 -74)
as Category Type 1I, Type 2II, or Type 3III, or IV as listed below:
1. Category ITvi e 1 wetlands are those that a) represent a uniaue or rare wetland
type; or b are more sensitive to disturbance than most wetlands: or c) are
relatively undisturbed and contain ecological attributes that are impossible to
replace within a human lifetime: or d) provide a high level of functions. The
following types of wetlands listed by Washington Department of Ecology and
potentially found in Tukwila's Shoreline Jurisdiction are Category I:
a. Estuarine wetlands (Estuarine wetlands are deenwater tidal habitats
with a range of fresh brackish- marine water chemistry and daily tidal
cycles, salt and brackish marshes. intertidal mudflats. mangrove
swamps, bays. sounds. and coastal rivers.
b. Wetlands that perform many functions well and score at least 70. points
in the Western Washington Wetlands Rating System.
more classes of vegetation;
Of
2. Category IlTvpe 2wetlands are difficult. though not impossible, to replace.
and provide high levels of some functions. These wetlands occur more
commonly than Category I wetlands. but still need a relatively high level of
protection. Category II wetlands potentially in. Tukwila's Shoreline
Jurisdiction i nclude:
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a. Estuarine Wetlands Any estuarine wetland smaller than an acre, or
those that are disturbed and larger than 1 acre are category II wetlands.
b. Wetlands That Perform Functions Well Wetlands scoring between
51 -69 points (out of 100) on the Questions related to the functions
present are Category II wetlands. -wetlands are thecc wetlands that
meet any of the following criteria:
aThe wetland is equal to or greater than one acre in size;
M=- w., rescIIec c` nesting site:; fef
cies as listed by the Washington State Department of Fish
and Wildlife; or
d. The wetland is hydrologically connected (non isolated) to a Type 1 or
Typo, 2 watercourse.
3. Category III wetlands have a moderate level of functions (scores between 30
50 points). Wetlands scoring between 30 -50 points generally have been
disturbed in some ways, and are often less diverse or more isolated from other
natural resources in the landscape than Category II wetlands.
4. Category IV wetlands have the lowest levels of functions (scores less than 30,
points) and are often heavily disturbed. While these are wetlands that should
be able to be replaced or improved, they still need protection because they
may provide some important functions, Any disturbance of these wetlands
must be considered on a case by case basis.
10.7 Watercourse Designation and Ratings
A. Watercourse ratings are based on the existing habitat functions and are rated as
follows:
1. Type 1 Watercourse: Watercourses inventoried as Shorelines of the State,
under RCW 90.58 (Green/Duwamish River).
2. Type 2 Watercourse: Those watercourses that have either perennial (year
round) or intermittent flows and support salmonid fish use.
3. Type 3 Watercourse: Those watercourses that have perennial flows and are
not used by salmonid fish.
4. Type 4 Watercourse: Those watercourses that have intermittent flows and are
not used by salmonid fish.
B. Watercourse sensitive area studies shall be performed by a qualified professional
(hydrologist, geologist, engineer or other scientist with experience in preparing
watercourse assessments).
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10.8 Fish and Wildlife Habitat Conservation Areas
A. Fish and wildlife habitat conservation areas within the shoreline jurisdiction include
the habitats listed below:
1. Areas with which endangered, threatened, and sensitive species have a
primary association;
2. Habitats and species of local importance, including but not limited to bald
eagle habitat, heron rookeries, osprey nesting areas;
3. Waters of the State (i.e., the Green Duwamish River itself);
4. State natural area preserves and natural resource conservation areas; and
5. Areas critical for habitat connectivity.
B. The approximate location and extent of known fish and wildlife habitat
conservation areas are identified in the Shoreline Inventory and Characterization Report
and are shown on the Sensitive Areas in the Shoreline Jurisdiction map Fish and
wildlife habitat conservation areas correlate closely with the areas identified as regulated
watercourses and wetlands and their buffers, as well as off channel habitat areas created
to improve salmon habitat (shown on the Sensitive Areas Map) in the Shoreline
jurisdiction. The Green/Duwamish River is recognized as the most significant fish and
wildlife habitat corridor. In addition Gilliam Creek, Riverton Creek, Southgate Creek,
Hamm Creek (in the north PAA), and Johnson Creek (South PAA) all provide salmonid
habitat.
10.9 Wetland Watercourse. and Fish and Wildlife Habitat Conservation Area
Buffers
A. Purpose and Intent of Buffer Establishment
1. A buffer area shall be established adjacent to designated sensitive areas. The
purpose of the buffer area shall be to protect the integrity, functions and
values of the sensitive areas. Any land alteration must be located out of the
buffer areas as required by this section.
2. Buffers are intended in general to:
a. Minimize long -term impacts of development on properties containing
sensitive areas;
b. Protect sensitive areas from adverse impacts during development;
c. Preserve the edges of wetlands and the banks of watercourses and fish
6 Note that only the salmon habitat enhancement project sites completed or underway
are shown as Fish and Wildlife Conservation Areas on the Sensitive Areas in the
Shoreline Jurisdiction Map. Streams are shown as watercourses. The river is not shown
as a Fish and Wildlife Habitat Conservation Area for the sake of simplicity.
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and wildlife habitat conservation areas for their critical habitat value;
d. Provide an area to stabilize banks, to absorb overflow during high
water events and to allow for slight variation of aquatic system
boundaries over time due to hydrologic or climatic effects;
e. Provide shading to watercourses and fish and wildlife habitat
conservation areas to maintain stable water temperatures and provide
vegetative cover for additional wildlife habitat;
f. Provide input of organic debris and nutrient transport in watercourses;
g. Reduce erosion and increased surface water runoff;
h. Reduce loss of or damage to property;
i. Intercept fine sediments from surface water runoff and serve to
minimize water quality impacts; and
j. Protect the sensitive area from human and domestic animal
disturbances.
C. Establishment of Buffer Widths
The following standard buffers shall be established:
1. Wetland buffers (measured from the wetland edge):
a. Categories I and II TypeWetlands; 100 foot buffer.
b. Cateeory IIIType-2 Wetland; 80 -foot buffer.
c. Cate2ory IVType 3 Wetland; 50 -foot buffer.
2. Watercourse buffers (measured from the Ordinary High Water Mark):
a. Type 1 Watercourse: The buffer width for the Green/Duwamish River
is established in the Shoreline Environment Designations of this SMP
for the three designated shoreline environments.
b. Type 2 Watercourse: 100 -foot -wide buffer.
c. Type 3 Watercourse: 80- foot -wide buffer.
d. Type 4 Watercourse: 50- foot -wide buffer.
3. Fish and Wildlife Habitat Conservation Areas: the buffer will be the same as
the river buffer established for each Shoreline Environment measured from
the OHWM, unless an alternate buffer is established and approved at the time
a Fish and Wildlife Habitat restoration project is undertaken.
D. Sensitive Area Buffer Setbacks
All commercial and industrial buildings shall be set back 15 feet and all other
development shall be set back ten feet from the sensitive area buffer's edge. The building
setbacks shall be measured from the foundation to the buffer's edge. Building plans shall
also identify a 20 -foot area beyond the buffer setback within which the impacts of
development will be reviewed. The Director may waive setback requirements when a site
plan demonstrates there will be no adverse impacts to the buffer from construction or
occasional maintenance activities.
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E. Reduction of Standard Buffer Width
Except for the Green/Duwamish River (Type 1 watercourse for which any variation in
the buffer shall be regulated under the shoreline provisions of this Program), the buffer
width may reduced on a case -by -case basis, provided the reduced buffer area does not
contain slopes 15% or greater. In no case shall the approved buffer width result in
greater than a 50% reduction in width. Buffer reduction with enhancement may be
allowed as part of a Substantial Development permit if:
1. Additional protection to wetlands or watercourses will be provided through
the implementation of a buffer enhancement plan;
2. The existing condition of the buffer is degraded;
3. Buffer enhancement includes, but is not limited to the following:
a. Planting vegetation that would increase value for fish and wildlife
habitat or improve water quality;
b. Enhancement of wildlife habitat by incorporating structures that are
likely to be used by wildlife, including wood duck boxes, bat boxes,
snags, root wads /stumps, birdhouses and heron nesting areas; or
c. Removing non native plant species and noxious weeds from the buffer
area and replanting the area.
F. Increase in Standard Buffer Width
Buffers for sensitive areas will be increased when they are determined to be particularly
sensitive to disturbance or the proposed development will create unusually adverse
impacts. Any increase in the width of the buffer shall be required only after completion of
a sensitive areas study by a qualified biologist that documents the basis for such increased
width. An increase in buffer width may be appropriate when:
1. The development proposal has the demonstrated potential for significant
adverse impacts upon the sensitive area that can be mitigated by an increased
buffer width; or
2. The area serves as habitat for endangered, threatened, sensitive or monitor
species listed by the federal government or the State.
G. Maintenance of Vegetation in Buffers
Every reasonable effort shall be made to maintain any existing viable native plant life in
the buffers. Vegetation may be removed from the buffer as part of an enhancement plan
approved by the Director Enhancements will ensure that slope stability and wetland or
watercourse quality will be maintained or improved. Any disturbance of the buffers shall
be replanted with a diverse plant community of native northwest species that are
appropriate for the specific site as determined by the Director. If the vegetation must be
removed, or because of the alterations of the landscape the vegetation becomes damaged
or dies, then the applicant for a permit must replace existing vegetation with comparable
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specimens, approved by the Director, which will restore buffer functions within five
years.
10.10 Areas of Potential Geologic Instability
A. Classification
Areas of potential geologic instability are classified as follows:
1. Class 1 area, where landslide potential is low, and which slope is less than
15
2. Class 2 areas, where landslide potential is moderate, which slope is between
15% and 40 and which are underlain by relatively permeable soils;
3. Class 3 areas, where landslide potential is high, which include areas sloping
between 15% and 40 and which are underlain by relatively impenneable
soils or by bedrock, and which also include all areas sloping more steeply than
40
4. Class 4 areas, where landslide potential is very high, which include sloping
areas with mappable zones of groundwater seepage, and which also include
existing mappable landslide deposits regardless of slope.
B. Exemptions
The following areas are exempt from regulation as geologically hazardous areas:
1. Temporary stockpiles of topsoil, gravel, beauty bark or other similar
landscaping or construction materials;
2. Slopes related to materials used as an engineered pre -load for a building pad;
3. Any temporary slope that has been created through legal grading activities
under an approved peitnit may be re- graded.
4. Roadway embankments within right -of -way or road easements; and
5. Slopes retained by approved engineered structures, except riverbank structures
and armoring.
C. Geotechnical Study Required
1. Development or alterations to areas of potential geologic instability that form
the river banks shall be governed by the policies and requirements of the
Shoreline Stabilization section of this SMP. Development proposals on all
other lands containing or threatened by an area of potential geologic
instability Class 2 or higher shall be subject to a geotechnical study. The
geotechnical report shall analyze and make recommendations on the need for
and width of any setbacks or buffers necessary to insure slope stability
Development proposals shall then include the buffer distances as defined
within the geotechnical report. The geotechnical study shall be performed by
a qualified professional geotechnical engineer, licensed in the State of
Washington.
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2. Prior to permitting alteration of an area of potential geologic instability, the
applicant must demonstrate one of the following:
a. There is no evidence of past instability or earth movement in the
vicinity of the proposed development, and where appropriate,
quantitative analysis of slope stability indicates no significant risk to
the proposed development or surrounding properties; or
b. The area of potential geologic instability can be modified or the
project can be designed so that any potential impact to the project and
surrounding properties is eliminated, slope stability is not decreased,
and the increase in surface water discharge or sedimentation shall not
decrease slope stability.
D. Buffers for Areas of Potential Geologic Instability
1. Buffers are intended to:
a. Minimize long -term impacts of development on properties containing
sensitive areas;
b. Protect sensitive areas from adverse impacts during development;
c. Prevent loading of potentially unstable slope formations;
d. Protect slope stability;
e. Provide erosion control and attenuation of precipitation, surface water
and storm water runoff;
f. Reduce loss of or damage to property; and
g. Prevent the need for future shoreline armoring.
2. Buffers may be increased by the Director when an area is determined to be
particularly sensitive to the disturbance created by a development. Such a
decision will be based on a City review of the report as prepared by a
qualified geotechnical engineer and by a site visit.
E. Additional Requirements
1. Where any portion of an area of potential geologic instability is cleared for
development, a landscaping plan for the site shall include tree replanting in
accordance with the Vegetation Protection and Landscaping chapter of this
SMP. Vegetation shall be sufficient to provide erosion and stabilization
protection.
2. It shall be the responsibility of the applicant to submit, consistent with the
findings of the geotechnical report, structural plans which were prepared and
stamped by a structural engineer. The plans and specifications shall be
accompanied by a letter from the geotechnical engineer who prepared the
geotechnical report stating that in his/her judgment, the plans and
specifications conform to the recommendations in the geotechnical report; the
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risk of damage to the proposed development site from soil instability will be
minimal subject to the conditions set forth in the report; and the proposed
development will not increase the potential for soil movement.
3. Further recommendations signed and sealed by the geotechnical engineer shall
be provided should there be additions or exceptions to the original
recommendations based on the plans, site conditions or other supporting data.
If the geotechnical engineer who reviews the plans and specifications is not
the same engineer who prepared the geotechnical report, the new engineer
shall, in a letter to the City accompanying the plans and specifications, express
his or her agreement or disagreement with the recommendations in the
geotechnical report and state that the plans and specifications conform to his
or her recommendations.
4. The architect or structural engineer shall submit to the City, with the plans and
specifications, a letter or notation on the design drawings at the time of permit
application stating that he or she has reviewed the geotechnical report,
understands its recommendations, has explained or has had explained to the
owner the risks of loss due to slides on the site, and has incorporated into the
design the recommendations of the report and established measures to reduce
the potential risk of injury or damage that might be caused by any earth
movement predicted in the report.
5. The owner shall execute a Sensitive Areas Covenant and Hold Harmless
Agreement running with the land, on a form provided by the City. The City
will file the completed covenant with the King County Department of Records
and Elections at the expense of the applicant or owner. A copy of the recorded
covenant will be forwarded to the owner.
6. Whenever the City determines that the public interest would not be served by
the issuance of a permit in an area of potential geologic instability without
assurance of a means of providing for restoration of areas disturbed by, and
repair of property damage caused by, slides arising out of or occurring during
construction, the Director may require assurance devices.
7. Where recommended by the geotechnical report, the applicant shall retain a
geotechnical engineer (preferably retain the geotechnical engineer who
prepared the final geotechnical recommendations and reviewed the plans and
specifications) to monitor the site during construction.. If a different
geotechnical engineer is retained, the new geotechmical engineer shall submit
a letter to the City stating whether or not he /she agrees with the opinions and
recommendations of the original study. Further recommendations, signed and
sealed by the geotechnical engineer, and supporting data shall be provided
should there be exceptions to the original recommendations.
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8. During construction the geotechnical engineer shall monitor compliance with
the recommendations in the geotechnical report, particularly site excavation,
shoring, soil support for foundations including piles, subdrainage installations,
soil compaction and any other geotechnical aspects of the construction. Unless
otherwise approved by the City, the specific recommendations contained in
the soils report must be implemented. The geotechnical engineer shall provide
to the City written, dated monitoring reports on the progress of the
construction at such timely intervals as shall be specified. Omissions or
deviations from the approved plans and specifications shall be immediately
reported to the City. The final construction monitoring report shall contain a
statement from the geotechnical engineer that, based upon his or her
professional opinion, site observations and testing during the monitoring of
the construction, the completed development substantially complies with the
recommendations in the geotechnical report and with all geotechnical- related
permit requirements. Occupancy of the project will not be approved until the
report has been reviewed and accepted by the Director.
9. Substantial weight shall be given to ensuring continued slope stability and the
resulting public health, safety and welfare in determining whether a
development should be allowed.
10. The City may impose conditions that address site -work problems which could
include, but are not limited to, limiting all excavation and drainage installation
to the dry season, or sequencing activities such as installing erosion control
and drainage systems well in advance of construction. A permit will be denied
if it is determined by the Director that the development will increase the
potential of soil movement that results in an unacceptable risk of damage to
the proposed development, its site or adjacent properties.
10.11 Sensitive Areas Permitted Uses and Alterations.
A. General Sensitive Areas Permitted Uses
1. All uses permitted in the Shoreline Jurisdiction Buffers are allowed in
sensitive area buffers within the jurisdiction except:
a. Promenades
b. Recreational structures
c. Public pedestrian bridges
d. Vehicle bridges
e. New utilities
f Plaza connectors
g. Water dependent uses and their structures
h. Essential streets, roads and rights of way
i. Essential public facilities
j. Outdoor storage
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2. In addition, the following uses are allowed:
a. Maintenance activities of existing landscaping and gardens in a
sensitive area buffer including but not limited to mowing lawns,
weeding, harvesting and replanting of garden crops and pruning and
planting of vegetation. The removal of established native trees and
shrubs is not permitted. Herbicide use in sensitive areas or their
buffers is not allowed without written permission of the City.
b. Vegetation maintenance as part of sensitive area enhancement,
creation or restoration. Herbicide use in sensitive areas or their buffers
is not allowed without written permission of the City.
B. Uses Requiring a Type II permit
1. Maintenance and repair of existing uses and facilities where alteration or
additional fill materials will be placed or heavy construction equipment used.
2. Construction of new essential streets and roads, rights -of -way and utilities.
3. New surface water discharges to sensitive areas or their buffers from detention
facilities, pre settlement ponds or other surface water management structures
may be allowed provided that the discharge meets the clean water standards of
RCW 90.48 and WAC 173.200 and 173.201 as amended, and does not
adversely affect water level fluctuations in the wetland or adversely affect
watercourse habitat and watercourse flow conditions relative to the existing
rate.
4. Plaza connectors
5. Essential public facilities
6. Overwater structures
7. Recreation structures
C. Conditional Uses
Dredging, where necessary to remediate contaminated sediments, if adverse impacts are
mitigated.
D. Wetland Alterations.
Alterations to wetlands are discouraged, are limited to the minimum necessary for project
feasibility, and must have an approved mitigation plan developed in accordance with the
standards in this chapter.
1. Mitigation for wetlands shall follow the mitigation seauencing steps in this
chapter and may include the following types of actions:
a. Creation the manipulation of the physical. chemical or biological
characteristics to develop a wetland on an upland or deepwater site,
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where a biological wetland did not previously exist;
b. Re- establishment the manipulation of the physical. chemical or
biological characteristics of a site with the goal of restoring wetland,
functions to a former wetland. resulting in a net increase in wetland
acres and functions;
c. Rehabilitation the manipulation of the physical. chemical, or
biological characteristics with the goal of repairing historic functions
and processes of a degraded wetland. resulting in a gain in wetland
function but not acreage;
d Enhancement the manipulation of the physical. chemical or
biological characteristics to heighten. intensify. or improve specific
functions (such as vegetation) or to change the growth stage or
composition of the vegetation present, resulting in a change in wetland
functions but not in a gain in wetland acreage; or
e. A combination of the three types. Mitigation for any alteration to a
restoration and 3:1 for enhancement
2. Allowed alterations per wetland type and mitigation ratios are as follows:
a. Alterations are not permitted to Category I or II Type 1 wetlands
unless specifically exempted under the provisions of this Program.
Mitigation will still be required at a rate of 3:1 for creation or re-
establishment, 4:1 for rehabilitation. and 6:1 for enhancement.
b. Alterations to Category IIIType 2 wetlands are prohibited except
where the location or configuration of the wetland provides practical
difficulties that can be resolved by modifying up to .10 (one- tenth) of
an acre of wetland. Mitigation for any alteration to a Category IIIType
2 wetland must be located contiguous to the altered wetland.
Mitigation for any alteration to a Category III wetland must be
provided at a ratio of 2:1 for creation or re- establishment, 4:1 for
rehabilitation and 8:1 for enhancement alone.
c.. Alterations to Category IVTypc 3 wetlands are allowed, where
unavoidable and adequate mitigation is carried out in accordance with
the standards of this section. Mitigation for alteration to a Category IV
wetland will be 1.5:1 for creation or re- establishment and 3:1 for
rehabilitation or enhancement.
d. Isolated wetlands formed on fill material in highly disturbed
environmental conditions and assessed as having low overall wetland
functions (scoring below 20 points) may be altered and/or relocated
with the permission of the Director. These wetlands may include
artificial hydrology or wetlands unintentionally created as the result of
construction activities. The determination that a wetland is isolated is
made by the US Army Corps of Engineers.
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D. Watercourse Alterations
All impacts to a watercourse that degrade the functions and values of the watercourse
shall be avoided. If alternation to the watercourse is unavoidable, all adverse impacts
shall be mitigated in accordance with the approved mitigation plan as described in this
chapter. Mitigation shall take place on -site or as close as possible to the impact location,
and compensation shall be at a minimuml:1 ratio. Any mitigation shall result in
improved watercourse functions over existing conditions.
1. Diverting or rerouting may only occur with the permission of the Director and
an approved mitigation plan. Any watercourse that has critical wildlife habitat
or is necessary for the life cycle or spawning of sahnonids, shall not be
rerouted, unless it can be shown that the habitat will be improved for the
benefit of the species. A watercourse may be rerouted or day- lighted as a
mitigation measure to improve watercourse function.
2. Piping of any watercourse should be avoided. Relocation of a watercourse is
preferred to piping; if piping occurs in a watercourse sensitive area, it shall be
limited and shall require approval of the Director. Piping of Type 1
watercourses shall not be permitted. Piping may be allowed in Type 2, 3 or 4
watercourses if it is necessary for access purposes. Piping may be allowed in
Type 4 watercourses if the watercourse has a degraded buffer, is located in a
highly developed area and does not provide shade, temperature control etc. for
habitat. The applicant must comply with the conditions of this section,
including: providing excess capacity to meet needs of the system during a
100 -year flood event; and providing flow restrictors, and complying with
water quality and existing habitat enhancement procedures.
3. No process that requires maintenance on a regular basis will be acceptable
unless this maintenance process is part of the regular and normal facilities
maintenance process or unless the applicant can show funding for this
maintenance is ensured for as long as the use remains.
4. Piping projects shall be performed pursuant to the following applicable
standards:
a. The conveyance system shall be designed to comply with the standards
in current use and recommended by the Department of Public Works.
b. Where allowed, piping shall be limited to the shortest length possible
as determined by the Director to allow access onto a property.
c. Where water is piped for an access point, those driveways or entrances
shall be consolidated to serve multiple properties where possible, and
to minimize the length of piping.
d. When required by the Director, watercourses under drivable surfaces
shall be contained in an arch culvert using oversize or super span
culverts for rebuilding of a streambed. These shall be provided with
check dams to reduce flows, and shall be replanted and enhanced
according to a plan approved by the Director.
e. All watercourse crossing shall be designed to accommodate fish
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E. Fish and Wildlife Conservation Area Alterations
Alterations to the Green/Duwamish River are regulated by the shoreline provisions of this
SMP. Alterations to Fish and Wildlife Conservation Areas that have been created as
restoration or habitat enhancement sites and that are shown on the Sensitive Areas in the
Shoreline Jurisdiction Map are prohibited and may only be authorized through a shoreline
variance procedure.
10.12 Sensitive Areas Mitigation
Mitigation shall be required for any proposals for dredging, filling, piping, diverting,
relocation or other alterations of sensitive areas in as allowed in this chapter and in
accordance with mitigation sequencing and the established mitigation ratios. The
mitigation plan shall be developed as part of a sensitive area study by a qualified
specialist.
A. Mitigation Sequencing.
passage. Watercourse crossings shall not block fish passage where the
streams are fish bearing.
f. Storm water runoff shall be detained and infiltrated to preserve the
watercourse channel's dominant discharge.
g. All construction shall be designed to have the least adverse impact on
the watercourse, buffer and surrounding environment.
h. Piping shall be constructed during periods of low flow, or as allowed
by the State Department of Fish and Wildlife.
i. Water quality must be as good or better for any water exiting the pipe
as for the water entering the pipe, and flow must be comparable.
Applicants shall demonstrate that reasonable efforts have been examined with the intent
to avoid and minimize impacts to sensitive areas and buffers. When an alteration to a
sensitive area or its required buffer is proposed, such alteration shall be avoided,
minimized or compensated for in the following order of preference:
1. Avoidance of sensitive area and buffer impacts, whether by finding another
site or changing the location of the proposed activity on -site;
2. Minimizing sensitive area and buffer impacts by limiting the degree of impact
on site;
3. Mitigation actions that require compensation by replacing, enhancing, or
substitution.
B. Criteria for Approval of Alterations and Mitigation
Alterations and mitigation plans are subject to Director approval, and may be approved
only if the following findings are made:
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1. The alteration will not adversely affect water quality;
2. The alteration will not adversely affect fish, wildlife, or their habitat;
3. The alteration will not have an adverse effect on drainage and/or stormwater
detention capabilities;
4. The alteration will not lead to unstable earth conditions or create an erosion
hazard or contribute to scouring actions;
5. The alteration will not be materially detrimental to any other property; and
6. The alteration will not have adverse effects on any other sensitive areas or the
shoreline.
7. The mitigation will result in improved functions such as water quality, erosion
control, wildlife and fish habitat.
C. Mitigation Location
1. On -site mitigation shall be provided, except where it can be demonstrated
that:
a. On -site mitigation is not scientifically feasible due to problems with
hydrology, soils, or other factors; or
b. Mitigation is not practical due to potentially adverse impacts from
surrounding land uses; or
c. Existing functional values created at the site of the proposed
restoration are significantly greater than lost sensitive area functions;
or
d. Established regional goals for flood storage, flood conveyance, habitat
or other sensitive area functions have been established and strongly
justify location of mitigation at another site.
2. Off -site mitigation shall occur within the shoreline jurisdiction in a location
where the sensitive area functions can be restored. Buffer impacts must be
mitigated at or as close as possible to the location of the impact.
3. Wetland creation, relocation of a watercourse, or creation of a new fish and
wildlife habitat shall not result in the new sensitive area or buffer extending
beyond the development site and onto adjacent property without the
agreement of the affected property owners, unless otherwise exempted by this
Shoreline Master Program.
D. Mitigation Plan Content and Standards
The scope and content of a mitigation plan shall be decided on a case -by -case basis. As
the impacts to the sensitive area increase, the mitigation measures to offset these impacts
will increase in number and complexity. The minimum components of a complete
mitigation plan are listed below. f�wsFor wetland mitigation plans, the format
should follow that established in Wetland Mitigation in Washington State. Part 2
Developing Mitigation Plans (Washington Department of Ecology, Corns of Engineers,
EPA, March 2006, as amended).
1. Baseline information of quantitative data collection or a review and synthesis
of existing data for both the project impact zone and the proposed mitigation
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site.
2. Environmental goals and objectives that describe the purposes of the
mitigation measures. This should include a description of site selection
criteria, identification of target evaluation species, and resource functions.
3. Performance standards for the specific criteria for fulfilling environmental
goals, and for beginning remedial action or contingency measures. They may
include water quality standards, species richness and diversity targets, habitat
diversity indices, or other ecological, geological or hydrological criteria. The
following shall be considered the minimum performance standards for
approved sensitive area alterations:
a. Sensitive area functions and improved habitat for fish and wildlife are
improved over those of the original conditions.
b. Hydrologic conditions, hydroperiods and watercourse channels are
improved over existing conditions and the specific performance
standards specified in the approved mitigation plan are achieved.
e. Acreage requirements for enhancement or creation are met.
f. Vegetation native to the Pacific Northwest is installed and vegetation
survival and coverage standards over time are met and maintained.
g. Buffer and bank conditions and functions exceed the original state.
h. Stream channel habitat and dimensions are maintained or improved
such that the fisheries habitat functions of the compensatory stream
reach meet or exceed that of the original stream.
4. A detailed construction plan of the written specifications and descriptions of
mitigation techniques. This plan should include the proposed construction
sequence and construction management, and be accompanied by detailed site
diagrams and blueprints that are an integral requirement of any development
proposal.
5. Monitoring and/or evaluation program that outlines the approach and
freauencv for assessing a- progress ofd the completed project. An outline
shall be included that spells out how the monitoring data will be evaluated and
reporteding, and frequency.
6. Maintenance plan that outlines the activities and frequency of maintenance to
ensure compliance with performance standards.
7. Contingency plan identifying potential courses of action and any corrective
measures to be taken when monitoring or evaluation indicates project
performance standards have not been met.
8. Performance security or other assurance devices.
E. Mitigation Timing
1. Mitigation projects shall be completed prior to activities that will permanently
disturb sensitive areas or their buffers and either prior to or immediately after
activities that will temporarily disturb sensitive areas.
2. Construction of mitigation projects shall be timed to reduce impacts to
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3. Monitoring of buffer alterations shall be required for three to five years. All
other alterations shall be monitored for minimum of five years.
F. Corrective Actions and Monitoring
The Director shall require subsequent corrective actions and long -term monitoring of the
project if adverse impacts to regulated sensitive areas or their buffers are identified.
G. Recording
The property owner receiving approval of a use or development pursuant to the Shoreline
Master Program shall record the City- approved site plan clearly delineating the sensitive
area and its buffer with the King County Division of Records and Elections. The face of
the site plan must include a statement that the provisions of this Chapter, as of the
effective date of the ordinance from which the Shoreline Management Program derives or
thereafter amended, control use and development of the subject property, and provide for
any responsibility of the latent defects or deficiencies.
H. Assurance Device
existing wildlife, flora and water quality, and shall be completed prior to use
or occupancy of the activity or development. The Director may allow
activities that permanently disturb wetlands or watercourses prior to
implementation of the mitigation plan under the following circumstances:
a. To allow planting or re- vegetation to occur during optimal weather
conditions;
b. To avoid disturbance during critical wildlife periods; or
c. To account for unique site constraints that dictate construction timing
or phasing.
1. The Director may require a letter of credit or other security device acceptable
to the City, to guarantee performance and maintenance requirements. All
assurances shall be on a form approved by the City Attorney.
2. When alteration of a sensitive area is approved, the Director may require an
assurance device, on a form approved by the City Attorney, to cover the
monitoring costs and correction of possible deficiencies for the term of the
approved monitoring and maintenance program. 3. The assurance device
shall be released by the Director upon receipt of written confirmation
submitted to the Department from the applicant's qualified professional that
the mitigation or restoration has met its performance standards and is
successfully established. Should the mitigation or restoration meet
performance standards and be successfully established in the third or fourth
year of monitoring, the City may release the assurance device early. The
assurance device may be held for a longer period, if at the end of the
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monitoring period, the performance standards have not been met or the
mitigation has not been successfully established.
3. Release of the security does not absolve the property owner of responsibility
for maintenance or correcting latent defects or deficiencies or other duties
under law.
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