HomeMy WebLinkAboutPN_Project_Narrative_240821_v1
Project Narrative
City of Renton
May Creek Trail South Project
Submitted to:
City of Renton
Community and Economic Development
Renton, Washington
On Behalf of Applicant:
City of Renton, Parks Planning & Natural Resources
Renton, Washington
August 2024
Submitted by
WSP USA
1201 Pacific Ave. Suite 550
Tacoma, Washington
30902211.000
Project Narrative WSP USA, 30902211.000 City of Renton, May Creek Trail South Soft Surface Trail and Bridge Project August 2024
Renton, Washington Page i of ii
PROJECT NARRATIVE
CITY OF RENTON
MAY CREEK TRAIL SOUTH PROJECT
TABLE OF CONTENTS
SECTION PAGE
1.0 SHORELINE NARRATIVE ............................................................................................. 1
1.1 Proposed Action ............................................................................................... 2
1.1.1 Soft Surface Trail Section ..................................................................... 2
1.1.2 Boardwalk Trail Section ........................................................................ 3
1.1.3 Abutments ............................................................................................. 3
1.1.4 Bridge ..................................................................................................... 3
1.1.5 Frontage Improvements ........................................................................ 3
1.2 Duration of Activities ........................................................................................ 4
1.2.1 Mobilization and Site Preparation ........................................................ 4
1.2.2 Soft Surface Trail Section ..................................................................... 5
1.2.3 Boardwalk Trail Section ........................................................................ 5
1.2.4 Bridge ..................................................................................................... 5
1.3 Minimization Measures and Best Management Practices .............................. 5
1.3.1 Minimization Measures ......................................................................... 5
1.4 Additional Site Information .............................................................................. 7
1.4.1 Special Site Features ............................................................................ 7
1.4.2 Soil Type and Drainage Conditions ..................................................... 7
1.4.3 Proposed Use of Property .................................................................... 8
1.4.4 Project Cost ........................................................................................... 8
1.4.5 Fill and Excavation ................................................................................ 8
1.4.6 Habitat Management ............................................................................. 8
1.4.7 Ordinary High Water Mark Work Distance/Shoreline .......................... 9
1.4.8 Project Height ........................................................................................ 9
2.0 MITIGATION DESCRIPTION ......................................................................................... 9
2.1 Assessments and Reports ............................................................................... 9
2.2 Utilities ..............................................................................................................10
3.0 STREAM STUDY NARRATIVE.....................................................................................10
3.1 Project Area Environmental Classification ....................................................10
3.2 Vegetative Cover ..............................................................................................10
3.3 Ecological Function .........................................................................................11
3.4 Fish and Wildlife ..............................................................................................11
3.4.1 Mammals ...............................................................................................11
3.4.2 Birds ......................................................................................................11
3.4.3 Amphibians and Reptiles .....................................................................12
3.4.4 Fish ........................................................................................................12
3.5 Measures to Protect Trees and Vegetation ....................................................13
3.6 No Net Loss of Ecological Function ...............................................................14
4.0 HABITAT DATA REPORT ............................................................................................14
4.1 Habitat Diversity ...............................................................................................14
Project Narrative WSP USA, 30902211.000 City of Renton, May Creek Trail South Soft Surface Trail and Bridge Project August 2024
Renton, Washington Page ii of ii
4.2 Migration Corridors .........................................................................................15
4.3 Species and Cover Types ................................................................................15
4.4 Identification of Disturbed Areas ....................................................................15
4.5 Existing Habitat Values and Functions ..........................................................16
4.5.1 Temperature .........................................................................................16
4.5.2 Water Quality ........................................................................................16
4.5.3 Vegetative Conditions ..........................................................................16
4.5.4 Habitat Values and Functions .............................................................17
4.6 Habitat Alterations and Impacts and Proposed Habitat Management
Program ............................................................................................................17
5.0 REFERENCES ..............................................................................................................18
6.0 LIST OF ACRONYMS AND ABBREVIATIONS ............................................................20
LIST OF TABLES
Table 1. Required Permits ....................................................................................................... 2
Table 2. Project Element Quantities ....................................................................................... 4
LIST OF APPENDICES
Appendix A – 60% Plan Set
Project Narrative WSP USA, 30902211.000 City of Renton, May Creek Trail South Soft Surface Trail and Bridge Project August 2024
Renton, Washington Page 1 of 20
PROJECT NARRATIVE
CITY OF RENTON
MAY CREEK TRAIL SOUTH PROJECT
1.0 SHORELINE NARRATIVE
The City of Renton Parks Planning and Natural Resources (City) proposes the May
Creek Trail South Project (Project), a soft surface trail, pedestrian bridge, and
frontage improvements at May Creek Greenway in Renton, Washington (See
Appendix A). The project area is located in King County in Section 32 of Township
24N Range 05E. The project area consists of the trail, boardwalks, graded areas,
bridge, and restoration areas within the 8.21-acre tax parcel 322405-9109 and the
frontage improvements on the ROW along Lake Washington Boulevard North, and is
defined as the limits of the Project that will be affected directly or indirectly by the
Project. Under existing City of Renton zoning, the site is classified as R-6,
Residential 6 Dwelling Units/Acre. The current comprehensive plan updated by
Ordinance #6029 effective 10/27/2021 is COR, Commercial Office Residential. The
existing land use at the project site is a publicly accessed City owned greenway.
The proposed soft surface trail will be one-quarter mile in length, consisting of an
approximate 6 ft width trail with portions at existing grade with two spurs (Spur 1 and
Spur 2) leading to viewing areas, and above grade boardwalk portions at areas that
cross wetlands, and will tie into an existing trail on the north side of the creek. The
bridge will be approximately 100 ft length, approximately 6 ft width, and will cross
May Creek at the eastern portion of the site. The trail is designed to be a Trail Class 4
to meet the existing classification and both the trail and bridge will conform to the
Americans with Disabilities Act (ADA) (See Appendix A).
The proposed action will involve minimal work within the 100-year floodplain – an
approximately 50 ft length of trail Spur 2 and temporary construction laydowns along
the north side of May Creek will be located within the 100-year floodplain. The trail
section will match the existing conditions and would not remove or place excess
native soil or fill and the construction access will consist of clearing of vegetation for
crane access and no cut or fill is anticipated to be required for this laydown. The
laydown will also be ripped and replanted after construction. This is the only trail
section within the 100-year floodplain. Two trail sections will cross existing wetland
drainage areas and will be a boardwalk in these locations. The bridge is a span that
will not impact the waterway and the bridge abutments will be positioned above the
OHWM, floodway, and 100-year floodplain. In addition to the trail, frontage
improvements will be required by the City from the May Creek bridge to the trail
entrance south of the bridge.
A portion of work occurs over the waters of the United States (WOTUS) (i.e. the
adjacent wetlands and May Creek), specifically the boardwalk sections of the trail. It
is not anticipated that the project will require a Section 404 permit from the U.S.
Army Corps of Engineers (USACE). This is based on 40 C.F.R. § 232.2 that defines
Project Narrative WSP USA, 30902211.000 City of Renton, May Creek Trail South Soft Surface Trail and Bridge Project August 2024
Renton, Washington Page 2 of 20
pilings associated with elevated walkways (i.e. boardwalks) do not have the effect of
fill. This determination is still under review by the USACE and the below table takes
this into consideration. All permits required for this project are listed below in Table
1.
The purpose of this project narrative is to meet the requirements set forth under
Renton Municipal Code (RMC) 4-8-120C (Submittal Requirements – Specific to
Application Type: Land Use Applications).
Table 1. Required Permits
Permit Agency
State Environmental Protection Act (SEPA) City of Renton
Shoreline Substantial Development Permit
(SSDP) City of Renton
Critical Areas Review City of Renton
Land Use Permit City of Renton
1.1 PROPOSED ACTION
The purpose of the Project is to construct a soft surface trail, build a bridge crossing
of May Creek, restore riparian habitat, and construct the City-required frontage
improvements at the May Creek Greenway in Renton, Washington (Appendix A).
The proposed soft surface trail will be one-quarter mile in length, consisting of an
approximate 6 ft width trail with 1 foot shoulders at existing grade with two spurs
(Spur 1 and Spur 2) leading to viewing areas. The trail will have portions located on a
boardwalk where the trail intersects wetlands and will tie into an existing trail on the
north side of the creek. The bridge will be approximately 100 ft in length,
approximately 6 ft in width and will cross May Creek at the eastern portion of the
site. The boardwalk trail and bridge will have grated decking and the entirety of the
trail will conform to ADA accessibility guidelines. The frontage improvements
consist of adding approximately 100 feet of new sidewalk construction, a new
stormwater drainage feature would flow off the roadway under the sidewalk into
Wetland A, and a replaced stormwater outfall to Wetland A where the trail starts off
of Lake Washington Boulevard North.
Additional details of project components are described below and Appendix A has the
60% Plan Set.
1.1.1 Soft Surface Trail Section
The trail will be cut into the existing grade and will have a negative cross slope to the
outside edge for drainage along hillslopes and crowned along flat sections. The trail
will consist of a 6-ft tread and 1-ft shoulders on each side. The surfacing of the trail
will be fine bark mulch and the base material will be crushed stone. The grade will
maintain a slope under 7% grade to maintain ADA accessibility and the cut and fill
sections will maintain a 2:1 slope throughout these sections. Where fill is required,
fill will be reused from cuts on site or imported as needed and compacted to build up
the subbase.
Project Narrative WSP USA, 30902211.000 City of Renton, May Creek Trail South Soft Surface Trail and Bridge Project August 2024
Renton, Washington Page 3 of 20
1.1.2 Boardwalk Trail Section
The proposed May Creek Trail South boardwalk will cross a wetland delineated by
WSP in October 2022 and January 2023 and labeled as Wetland C in two (2)
locations for a total of approximately 270 ft. These crossings will transition from the
soft surface trail section to a boardwalk section. The boardwalk will consist of a
timber boardwalk with a fiber-reinforced plastic (FRP) board slatted deck surface to
allow drainage. The boardwalk will be supported by micro piles and will have
handrails and/or bull rails for pedestrian safety.
1.1.3 Abutments
Concrete bridge abutments will be positioned above the OHWM, floodway, and 100-
year floodplain. Approximately 12 cubic yards of material will be excavated at the
abutment area to accommodate placement of the new concrete abutments. The
abutments will be supported by driven micropiles, cast-in-place, and will be
backfilled with gravel.
1.1.4 Bridge
The 100 ft length and 6 ft width clear span bridge will be comprised of concrete
walkways at the north and south portion of the bridge at the abutment locations, and
an aluminum gangway type bridge with non-slip FRP slatted decking for the length of
the bridge in between the concrete walkways. The bridge measures 600 square feet
total, and approximately 240 square feet of this total is located over water as
measured from the OHWM. The bridge will be positioned approximately 2 ft above
the OHWM.
1.1.5 Frontage Improvements
Lake Washington Boulevard will be improved to include new sidewalks for access to
the trail. The sidewalks will be tied into the existing May Creek bridge and will end at
the trail entrance to the south. The sidewalks will be 5 feet in width and will include
one small retaining wall near the existing fire hydrant. An existing power pole owned
by Puget Sound Energy will be repositioned outside of the sidewalk and not within
Wetland A. A new stormwater pipe will be placed under the new sidewalk and
discharge to Wetland A. The existing roadway will be sawcut and new hot mix
asphalt will be applied up to the center of the new road, maintaining the existing
crown.
Table 2 summarizes project quantities.
Project Narrative WSP USA, 30902211.000 City of Renton, May Creek Trail South Soft Surface Trail and Bridge Project August 2024
Renton, Washington Page 4 of 20
Table 2. Project Element Quantities
Project Element Quantity
Bridge Area ~600 SF
Soft Trail Area ~5,900 SF
Boardwalk Area ~1,720 SF
Graded Area (including trail) ~14,830 SF
Sidewalk Area ~650 SF
Cut Volume 200 CY
Fill Volume 260 CY
Mitigation/Planting ~3.28 AC
1.2 DURATION OF ACTIVITIES
The project is currently at the 60% design phase with site invasives species
management work started in spring 2023, construction to start in spring 2025,
completion in fall 2025, and invasive species restoration work to continue through
2026.
Work days are anticipated to be 7:00AM through 8:00PM Monday through Friday,
excluding federal holidays, for the duration of the project.
Hauling and transportation routes will be by Interstate 405 (I-405) to the east and
Lake Washington Boulevard N to the west, which border the site. Bridge construction
access is anticipated to be from I-405, and trail construction and laydown areas are
anticipated to be accessed from Lake Washington Boulevard N. The contractor will
submit a traffic control plan as required.
The project will be completed in phases described in the following sections.
Construction of all elements will occur outside of the May Creek OHWM and are not
subject to an in-water work window.
1.2.1 Mobilization and Site Preparation
This phase consists of clearing, grubbing, and removing trees that are within the trail,
boardwalk, bridge alignment and abutments, and construction laydown areas
associated with the placement of the bridge. The construction access is preliminary at
this point in design and is anticipated to be achieved through working with
Washington State Department of Transportation (WSDOT) on the ongoing I-405
construction access. The bridge sections and crane are anticipated to come into the
site from the I-405 construction access and be installed on the western flank of the
proposed bridge alignment. A 40 ft clear zone is the assumed clearing limits
necessary to stage the crane and allow for the placement of the span sections onto the
footings. The foundations will be prepped either by hand or with a mini-excavator. To
access the southern foundation, the contractor will either place girders over the stream
Project Narrative WSP USA, 30902211.000 City of Renton, May Creek Trail South Soft Surface Trail and Bridge Project August 2024
Renton, Washington Page 5 of 20
or use the crane to pass the mini-excavator over May Creek or will use the completed
boardwalk to access the abutment.
1.2.2 Soft Surface Trail Section
The trail will be cut into the existing grade and will be sloped to the outside edge for
drainage along hillslopes and crowned along flat sections. The trail will consist of a 6
ft tread with 1 ft shoulders on each side. The surfacing of the trail will be fine bark
mulch over a crushed stone base.
1.2.3 Boardwalk Trail Section
The proposed May Creek Trail South section will cross Wetland C in two (2)
locations for a total of approximately 270 ft. These crossings will transition from the
soft surface trail section to a boardwalk section. The boardwalk will consist of a
timber boardwalk with a FRP board slatted deck surface to allow for drainage. The
boardwalk will be supported by micro piles and will have handrails and/or bull rails
for pedestrian safety.
1.2.4 Bridge
The 100 ft length and 6 ft width clear span bridge will be comprised of concrete
walkways at the north and south portion of the bridge at the abutment locations, and
an aluminum gangway type bridge with non-slip FRP slatted decking for the length of
the bridge in between the concrete walkways. The bridge measures 600 square feet
total, and approximately 240 square feet of this total is located over water as
measured from the OHWM. The bridge will be positioned approximately 2 ft above
the OHWM. The bridge will be placed in sections via a crane, supported either via
cantilevering and temporarily shored, and bolted together to form the clear span.
1.3 MINIMIZATION MEASURES AND BEST MANAGEMENT PRACTICES
The proposed project will not result in a loss of WOTUS and, thus, will have
insignificant effect on the surrounding aquatic habitat. The project will result in a net
public access gain and will not alter the existing floodway and will not impede May
Creek. A small spur of the trail and construction equipment will enter the 100 year
floodplain with no net cut or fill occurring within it.
In addition, the following minimization measures and best management practices
(BMPs) will be employed during construction to minimize project impacts.
1.3.1 Minimization Measures
• No in-water work is proposed.
• Project construction will be completed in compliance with Washington State
Water Quality Standards (Washington Administrative Code [WAC] 173-201A),
including:
− Petroleum products, fresh cement, lime, concrete, chemicals, or other toxic or
deleterious materials will not be allowed to enter surface waters.
− There will be no discharge of oil, fuels, or chemicals to surface waters or onto
land where there is a potential for reentry into surface waters.
Project Narrative WSP USA, 30902211.000 City of Renton, May Creek Trail South Soft Surface Trail and Bridge Project August 2024
Renton, Washington Page 6 of 20
• The contractor will prepare a spill prevention, control, and countermeasures
(SPCC) plan, and it will be used during all construction operations. A copy of the
plan with any updates will be maintained at the work site.
− The SPCC plan will outline BMPs, responsive actions in the event of a spill or
release, and notification and reporting procedures. The plan will also outline
management elements, such as personnel responsibilities, project site security,
site inspections, and training.
− The SPCC plan will outline the measures to prevent the release or spread of
hazardous materials found on site or encountered during construction but not
identified in contract documents, including any hazardous materials that are
stored, used, or generated on site during construction. These items include, but
are not limited to, gasoline, diesel fuel, oils, and chemicals.
− Applicable spill response equipment and material designated in the SPCC plan
will be maintained at the job site.
• Corrective actions will be taken in the event of any discharge of oil, fuel, or
chemicals into the water, including the following:
− Containment and cleanup efforts will begin immediately upon discovery of
the spill and be completed in an expeditious manner in accordance with all
local, state, and federal regulations. Spill response will take precedence over
normal work. Cleanup will include proper disposal of any spilled material and
used cleanup material.
− The cause of the spill will be ascertained and appropriate actions taken to
prevent further incidents or environmental damage.
− Spills will be reported to the Washington State Department of Ecology’s
(Ecology) Northwest Regional Spill Response Office at 425-649-7000.
• Excess or waste materials will not be disposed of or abandoned waterward of the
OHWM or allowed to enter waters of the state. Waste materials will be disposed
of in an appropriate manner consistent with applicable local, state, and federal
regulations.
• Demolition and construction materials will not be stored where upland runoff can
cause materials to enter surface waters.
• Oil-absorbent materials will be present on site to use in the event of a spill or if
any oil product is observed in the water.
• Silt fence will be installed to prevent excavated material from entering May
Creek.
• High visibility construction fencing will be installed where needed around the
perimeter.
Project Narrative WSP USA, 30902211.000 City of Renton, May Creek Trail South Soft Surface Trail and Bridge Project August 2024
Renton, Washington Page 7 of 20
1.4 ADDITIONAL SITE INFORMATION
The purpose of this section is to provide the remaining Project Narrative information
listed in the City of Renton’s Shoreline Substantial Development Permit Submittal
Requirements.
1.4.1 Special Site Features
The project site is bordered by Interstate 405 (I-405) to the east and bordered by Lake
Washington Boulevard N to the west. May Creek runs through the site and there is an
existing nature trail, May Creek Trail, on the north side of May Creek. May Creek
(Type-S water), floodway, and 100-year floodplain span a majority of the central and
northern portions of the project parcel. There are four (4) wetlands located with the
parcel, delineated in October 2022 and January 2023 by WSP and documented in the
May Creek Trail Project Wetlands and Waterbodies Delineation and Assessment
Report. These wetlands have been labeled as Wetland A, Wetland B, Wetland C, and
Wetland D.
The wetlands are rated as Category III with Wetlands A, B, and C located to the south
of May Creek and Wetland D to the north of May Creek. Sources of hydrology for
the wetlands vary with Wetland A likely coming from a seasonally high water table
and surface water flow from a culvert along Lake Washington Boulevard North,
Wetland B is likely from a seasonally high water table and overbank flooding from
May Creek, Wetland C is from a perennial groundwater seep, high water table, and
overbank flooding from May Creek, and Wetland D is from a seasonally high water
table. Each wetland also receives direct precipitation, and interflow through soil
mediums. Wetlands will be described in detail in the Wetland, Lake, and Stream
Study report to be submitted with the final application.
1.4.2 Soil Type and Drainage Conditions
US Department of Agriculture Natural Resources Conservation Service (USDA-
NRCS) Web Soil Survey identifies the following soil mapping units within the study
area. The following descriptions are excerpted from the King County Area soil
survey:
• Alderwood gravelly sandy loam, 8 to 15 percent slopes (AgC) – This soil unit
formed from glacial drift and outwash and is common in Western
Washington. The unit is moderately well drained and is typically used for
timber and crop production or wildlife habitat. According to the state Soil
Data Access (SDA) Hydric Soil List, this soil is listed as hydric in King
County Area.
• Indianola loamy sand, 5 to 15 percent slopes (InC) – This soil unit formed in
sandy glacial drift and is somewhat common in the Puget Sound lowlands.
The unit is somewhat excessively well drained and is typically used for timber
and forage production or pastures. According to the state SDA, this soil is
listed as hydric in the King County Area.
Project Narrative WSP USA, 30902211.000 City of Renton, May Creek Trail South Soft Surface Trail and Bridge Project August 2024
Renton, Washington Page 8 of 20
• Normal sandy loam (No) – This soil unit formed in old alluvium in
depressions on glacial till plains and drainageways. The unit is poorly drained.
No capability for timber production, but when drained can be used for row
crops and pasture. According to the state SDA, this soil is listed as hydric in
the King County Area.
Topographically, the south side of the site is an east-west slope down to May Creek
with the northern portion being relatively flat. Most of the site consists of
undeveloped forest. No pollution generating surfaces are located within the project
area.
1.4.3 Proposed Use of Property
The existing land use at the project site is as a publicly accessed City owned park
intended for public recreation. There is an existing nature trail, May Creek Trail, on
the north side of May Creek.
The proposed project will maintain the existing land use and create an additional
11,300 SF of trail and bridge that will connect to the existing trail, with the tallest
element as an approximately 10 ft high bridge with railings for pedestrian safety.
Parking for access will be achieved by an existing pull off located on Lake
Washington Boulevard N that provides access to the existing trail and the new park
and ride located to the northeast of the site east of I-405.
1.4.4 Project Cost
The approximate construction cost and fair market value of the proposed project is
$250,000, not including on-site mitigation.
1.4.5 Fill and Excavation
No new fill or permanent excavation is proposed below the OHWM of May Creek or
wetlands located at the project site. Approximately 14,830 SF of upland area will be
graded including buffers associated with May Creek and associated wetlands. Two
(2) bridge abutments will be installed that will require 12 CY of material excavated
for installation and backfill with gravel. Approximately 200 CY of cut and
approximately 260 CY of fill are required for grading associated with trail
construction and frontage road improvements. Of this, no cut or fill material is
required for grading in site wetlands or May Creek. The proposed trail will maintain a
maximum 7% slope for ADA access. Fill will be imported clean borrow material.
1.4.6 Habitat Management
Approximately 1,040 square feet of wetland and 23,450 square feet of riparian buffer
resources will be impacted by the project. Temporary and permanent impacts are
from clearing, excavating, and filling of each resource type. The impacts of the
proposed project are fully mitigated through on-site actions. On site mitigation
activities will generate approximately 0.48 acres of mitigation credits via
enhancement of the wetlands and riparian buffers through invasive species
management and the planting of native trees, shrubs, and herbaceous vegetation (See
Appendix A). On-site actions target improvements to stream and wetland ecological
Project Narrative WSP USA, 30902211.000 City of Renton, May Creek Trail South Soft Surface Trail and Bridge Project August 2024
Renton, Washington Page 9 of 20
functions that are impacted by the proposed project and have been historically
degraded by development of the adjacent roadway and historic landowners.
Planting will include native bare-root trees and shrubs installed through small
excavations dug by hand. All plants will be sourced locally and be from stocks native
to the Puget Sound lowlands. Plant materials will generally be in 1-gallon containers
or live stakes, but bare-root stock may be selected depending on timing and
availability.
Additional mitigation and habitat management will occur by removing multiple
infestations of invasive species and installing native riparian vegetation. Currently,
the entire site is covered in infestations of Himalayan blackberry (Rubus bifrons),
hybrid knotweed (Fallopia x bohemica), English ivy (Hedera helix), English holly
(Ilex aquifolium), Portuguese laurel (Prunus lusitanica), among others. The City of
Renton has partnered with King County Healthy Lands Project to develop a multi-
year management plan to remove, treat, and manage these species.
1.4.7 Ordinary High Water Mark Work Distance/Shoreline
During October and November 2022 site visits, WSP scientists marked the ordinary
high water mark (OHWM) of May Creek that extended from the bridge on Lake
Washington Boulevard North to the west up to the bridge on I-405 to the east. The
scientists used a combination of field indicators (e.g., vegetation distribution,
sediment lines on vegetation or other fixed objects, scour lines, etc.) to determine the
OHWM and marked it in the field with blue flagging (Shown on all plan view Sheets,
Appendix A).
There are four (4) wetlands located with the May Creek parcel, as documented in the
May Creek Trail Project Wetlands and Waterbodies Delineation and Assessment
Report. These wetlands have been labeled as Wetland A, Wetland B, Wetland C, and
Wetland D (Shown on all plan view Sheets, Appendix A).
May Creek contains natural cover such as overstory shade, LWD, and riparian
vegetation though water quality, riparian habitat, LWD, hydrology, and pools are
determined to be poor (Kerwin, 2001).
Lake Washington is located approximately 1,800 ft west of the site – May Creek
outfalls at this location.
1.4.8 Project Height
Tallest proposed structure is the bridge which will be approximately 10 feet from
ground level.
2.0 MITIGATION DESCRIPTION
2.1 ASSESSMENTS AND REPORTS
The following environmental analyses and reports have been generated or are under
development in association with the Project:
Project Narrative WSP USA, 30902211.000 City of Renton, May Creek Trail South Soft Surface Trail and Bridge Project August 2024
Renton, Washington Page 10 of 20
• Arborist Report – May Creek Trail South Project (Davey Resource Group,
2022).
• Geotechnical Report – May Creek Trail South Project – (PanGeo 2023).
• Wetlands and Waterbodies Delineation and Assessment Report May Creek
Trail South Project (WSP USA, 2024a).
• Mitigation and Habitat Management Plan – May Creek Trail South Project
(WSP USA, 2024b).
• Drainage Control Plan and Drainage Report – (WSP USA, 2024c).
• Biological Assessment – May Creek Trail South Project (WSP USA, 2024d).
2.2 UTILITIES
No utilities are identified within the site parcel and no utilities are proposed as part of
the Project. Adjacent utilities include a fire hydrant and overhead power line along
the eastern ROW of Lake Washington Boulevard N.
3.0 STREAM STUDY NARRATIVE
The proposed trail project meets the criteria for an SSDP under the City’s Shoreline
Master Program (SMP) provided that a stream study and wetland delineation report is
prepared by the applicant for the City in accordance with RMC Section 4-8-120D.2
(Stream or Lake Study, Standard and Wetland Delineation Report) and RMC 4-8-
120D.19 and RMC 4-8-120D.23. The following section has been prepared to meet
this requirement.
3.1 PROJECT AREA ENVIRONMENTAL CLASSIFICATION
The site includes May Creek which has a regulated shoreline classified as MC-B May
Creek Reaches (Renton, 2023). The site is classified as R-6, Residential 6 DU/Acre.
The current comprehensive plan updated by Ordinance #6029 effective 10/27/2021 is
COR, Commercial Office Residential.
3.2 VEGETATIVE COVER
A habitat survey of the site was conducted by two WSP environmental scientists in
October, 2022 and January 2023, to assess vegetative cover and to perform the
OHWM and wetland delineation documented in the May Creek Trail Project
Wetlands and Waterbodies Delineation and Assessment Report.
The majority of the site consists of undeveloped forest and shrub cover outside of the
existing trail alignment to the north of May Creek. Vegetation species noted
throughout the study area are mostly invasive species but include an overstory of
Douglas’ fir (Pseudotsuga menziesii), western hemlock (Tsuga heterophylla), bigleaf
maple (Acer macrophyllum), red alder (Alnus rubra), black cottonwood (Populus
balsamifera), and western red cedar (Thuja plicata), and an understory of Pacific
Project Narrative WSP USA, 30902211.000 City of Renton, May Creek Trail South Soft Surface Trail and Bridge Project August 2024
Renton, Washington Page 11 of 20
willow (Salix lasiandra), Sitka willow (Salix sitchensis), evergreen huckleberry
(Vaccinium ovatum), western skunk cabbage (Lysichiton americanus), lady fern
(Athyrium felix-femina), western common horsetail (Equisetum arvense) and non-
native Himalayan blackberry (Rubus armeniacus) Japanes/Bohemian knotweed
(Reynoutria bohemica), among other plant species.
The project site is located at May Creek Open Space Park (Park) in Renton,
Washington and is bordered by I-405 to the east and bordered by Lake Washington
Boulevard N and dense neighborhood to the west. May Creek runs through the site,
with an existing nature trail positioned to the north, and four (4) wetlands located at
the Park. The City owns the 8.21-acre parcel.
3.3 ECOLOGICAL FUNCTION
Stream habitats have important ecological functions other than providing habitat for
fish and wildlife, such as providing flooding areas where channel movement and
other hydrological systems occur, as well as important aesthetic and recreational
locations for the public.
The primary ecological functions provided by riparian habitat within the project
area include the following:
• Nesting and foraging habitat for birds and small mammals
• Input of terrestrial insects from overhanging vegetation
• Input of organic matter from falling leaves or branches
• Limited erosion control
• Water temperature maintenance
3.4 FISH AND WILDLIFE
This section addresses fish and wildlife species that may use May Creek and the Park
in the vicinity of the project site. The Biological Assessment prepared for this project
(WSP, 2024d) documents the ESA-listed species and critical habitat known to occur,
or with the potential to occur, within the project area.
3.4.1 Mammals
ESA-listed mammals with potential to occur within King County include:
• North American wolverine (Gulo gulo Iuscus) (USFWS, 2023)
However, there are no known occurrences of these species within the project vicinity
according to the WDFW’s Priority Habitat and Species list (WDFW, 2023).
In addition, the project site and action area is bordered by Interstate 405 (I-405) to the
east and bordered by Lake Washington Boulevard North and dense neighborhood to
the west. Due to the dense urban setting, the action area does not provide any suitable
habitat for these species.
3.4.2 Birds
ESA-listed birds with potential to occur within King County include:
Project Narrative WSP USA, 30902211.000 City of Renton, May Creek Trail South Soft Surface Trail and Bridge Project August 2024
Renton, Washington Page 12 of 20
• Marbled murrelet (Brachyramphus marmoratus)
• Yellow-billed cuckoo (Coccyzus americanus) (USFWS, 2023)
However, there are no known occurrences of these species within the project vicinity
according to the WDFW’s Priority Habitat and Species list (WDFW 2023) and no
suitable habitat is present within the vicinity of the site.
3.4.3 Amphibians and Reptiles
No amphibians were observed during the site visit.
The project site is located approximately 0.9 mile northeast of the mouth of the Cedar
River. Amphibian and reptile studies conducted within the lower Cedar River
identified the following species that could occur within the vicinity of the project site.
The following amphibian species have been documented in the lower Cedar River
(Richter and Anzous 1997).
• Ensatina (salamander) (Ensatina eschscholtzii)
• Long-toed salamander (Ambystoma macrodactylus)
• Northwestern salamander (Ambystoma gracile)
• Pacific tree frog (Pseudoacris regilla)
• Red-legged frog (Rana aurora)
• Western red-backed salamander (Plethodon vehiculum)
The following reptile species have been documented in the lower Cedar River
(Richter and Anzous 1997).
• Common garter snake (Thamnophis sirtalis)
• Northern alligator lizard (Elgaria coerulea)
• Northwestern garter snake (Thamnophis ordinoides)
• Painted turtle (Chrysemys picta)
• Rubber boa (Charina bottae)
• Slider (Trachemys scripta)
• Western fence lizard (Sceloporus occidentalis)
• Western terrestrial garter snake (Thamnophis elegans)
3.4.4 Fish
May Creek provides habitat for several fish species, including six salmonid species:
• Chinook salmon (Oncorhynchus tshawytscha)
• Steelhead (Oncorhynchus mykiss)
• Bull trout (Salvelinus confluentus)
• Sockeye salmon (Oncorhynchus nerka)
• Coho salmon (Oncorhynchus kisutch)
• Cutthroat Trout (Oncorhynchus clarki)
Three of the above species, Puget Sound Chinook salmon, Puget Sound steelhead,
and Coastal Puget Sound bull trout are listed as threatened under the ESA (NOAA
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Renton, Washington Page 13 of 20
NMFS, 2023). Other fish species that may be present within the project area include
sculpins (Cottus spp.), the northern pike minnow (Ptychocheilus oregonensis), and
peamouth (Mylocheilus caurinus) (Weitkamp, 2000; Wydoski, 2003).
3.5 MEASURES TO PROTECT TREES AND VEGETATION
Twenty-six (26) trees are identified to be protected during construction. The majority
of these trees are located adjacent to the proposed trail alignment and will be
protected from damage during trail installation. The following tree protection
measures are to be followed and are shown within Appendix A:
• Tree protection shall be installed prior to start of construction activities and
remain throughout the work as necessary to protect existing vegetation to
remain.
• The contractor shall not park vehicles or equipment, store materials or
stockpiled soil, dispose of building materials, chemicals, petroleum products,
or other detrimental substances within limits of tree protection fencing of any
existing tree to remain. The contractor shall protect existing trees from flame,
smoke, and heat. Construction access to site shall not occur beneath drip line
of existing trees until special provisions have been met to protect all existing
vegetation to remain. The contractor shall be responsible for all damage to
existing trees and plant material during construction. All clearing and
grubbing or excavation within limits of tree protection fencing shall be done
by hand methods.
• A temporary chain link construction fence shall be installed around the greater
of the protected tree dripline or surrounding a tree at a distance equal to or
greater than 1.25 feet for each 1-inch of trunk width located 3-feet above the
lowest grade. Temporary fence shall be installed to surround tree(s).
• Temporary chain link fabric to be minimum 11 gauge, galvanized. Do not use
rusted or malformed fabric.
• Posts shall be galvanized 2"∅ standard pipe posts or approved equal. Install
posts to avoided damage to major roots, and with sufficient embedment to
support fence. concrete fence post footings are acceptable over paved
surfaces.
• Roots 1-inch in diameter and greater exposed during construction shall have a
clean straight cut to remove damaged portion of root, and all exposed roots
shall be covered with topsoil immediately to prevent drying.
• Individual trees shall have temporary fencing place on four sides, with
placards installed on each side. Placards shall have the following words, "no
trespassing - protected trees".
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Renton, Washington Page 14 of 20
• Where excavating for new construction is required within limits of tree
protection fencing, excavate by hand to minimize damage to roots and
perform as follows:
o Use narrow tine spading forks and comb soil to expose roots.
o If main lateral roots are immediately adjacent to location of new
construction, the contractor shall notify the owner's representative
prior to any excavation.
o Do not allow exposed roots to dry out before permanent backfill is
placed.
o Provide temporary earth cover and/or moist organic mulch, or pack
with peat moss and wrap with burlap. Water and maintain the moist
condition until covered with backfill.
• Any tree exceeding 12 inches in caliper and larger, measured 3 feet above the
lowest grade immediately adjacent to the tree is considered a significant
existing tree. Any damage to a significant existing tree shall immediately be
reported to the city.
3.6 NO NET LOSS OF ECOLOGICAL FUNCTION
The impacts to the existing wetlands, stream banks, and riparian areas will be
mitigated for via enhancements to on-site wetlands and riparian buffers. The primary
objective of the mitigation plan is to have no net loss of ecological function present at
the Project Site.
The proposed mitigation includes four elements; (1) removal of the pervasive
invasive species present throughout the site in wetlands and riparian buffers, (2)
management of the invasive species in the future to control their proliferation, (3)
riparian enhancements through native riparian vegetation planting, and (4)
reestablishment of temporarily impacted riparian buffers from construction.
4.0 HABITAT DATA REPORT
This section comprises the Habitat Data Report, in accordance with RMC 4-8-120C
and is intended to document site-specific habitat and ecological function information.
4.1 HABITAT DIVERSITY
The action area includes the freshwater habitat of May Creek which contains natural
cover such as overstory shade, LWD, and riparian vegetation. The substrate within
the action area is primarily course gravels and cobbles with low sedimentation,
deposited in washes, riffles, and pools.
The majority of the site consists of undeveloped forest outside of the existing trail
alignment to the north of May Creek. Vegetation species noted throughout the study
area include mostly invasive species with an overstory of Douglas’ fir (Pseudotsuga
Project Narrative WSP USA, 30902211.000 City of Renton, May Creek Trail South Soft Surface Trail and Bridge Project August 2024
Renton, Washington Page 15 of 20
menziesii), western hemlock (Tsuga heterophylla), bigleaf maple (Acer
macrophyllum), red alder (Alnus rubra), black cottonwood (Populus balsamifera),
and western red cedar (Thuja plicata), and an understory of Pacific willow (Salix
lasiandra), Sitka willow (Salix sitchensis), evergreen huckleberry (Vaccinium
ovatum), western skunk cabbage (Lysichiton americanus), lady fern (Athyrium felix-
femina), western common horsetail (Equisetum arvense) and non-native Himalayan
blackberry (Rubus armeniacus) Japanes/Bohemian knotweed (Reynoutria bohemica),
among other plant species.
4.2 MIGRATION CORRIDORS
There are six salmonid species that may use May Creek as a migration corridor:
• Chinook salmon (Oncorhynchus tshawytscha)
• Steelhead (Oncorhynchus mykiss)
• Bull trout (Salvelinus confluentus)
• Sockeye salmon (Oncorhynchus nerka)
• Coho salmon (Oncorhynchus kisutch)
• Cutthroat Trout (Oncorhynchus clarki)
Three of the above species, Puget Sound Chinook salmon, Puget Sound steelhead,
and Coastal Puget Sound bull trout are listed as threatened under the ESA.
4.3 SPECIES AND COVER TYPES
The action area includes the freshwater habitat of May Creek which contains natural
cover such as overstory shade, LWD, and riparian vegetation. The substrate within
the action area is primarily course gravels and cobbles with low sedimentation,
deposited in washes, riffles, and pools.
The majority of the site consists of undeveloped forest outside of the existing trail
alignment to the north of May Creek. Vegetation species noted throughout the study
area include an overstory of Douglas’ fir (Pseudotsuga menziesii), western hemlock
(Tsuga heterophylla), bigleaf maple (Acer macrophyllum), red alder (Alnus rubra),
black cottonwood (Populus balsamifera), and western red cedar (Thuja plicata), and
an understory of Pacific willow (Salix lasiandra), Sitka willow (Salix sitchensis),
evergreen huckleberry (Vaccinium ovatum), western skunk cabbage (Lysichiton
americanus), lady fern (Athyrium felix-femina), western common horsetail
(Equisetum arvense) and non-native Himalayan blackberry (Rubus armeniacus)
Japanes/Bohemian knotweed (Reynoutria bohemica), among other plant species.
4.4 IDENTIFICATION OF DISTURBED AREAS
The project site is bordered by Interstate 405 (I-405) to the east and bordered by Lake
Washington Boulevard N to the west. May Creek runs through the site and an
existing nature trail, May Creek Trail, is on the north side of May Creek. Beyond the
parcel, dense developed neighborhoods surround the site, and a shopping center exists
to the east. The surrounding area is highly developed and disturbed.
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Renton, Washington Page 16 of 20
4.5 EXISTING HABITAT VALUES AND FUNCTIONS
In general, the environmental baseline conditions within the action area are
functioning. Most of the indicators of environmental condition are properly
functioning, or are functioning at risk, at both the action area and watershed scales.
The following habitat parameters are discussed in the sections below.
• Temperature
• Water quality
• Vegetative conditions of the riparian zone
4.5.1 Temperature
King County routinely monitors the ecological health of May Creek in a variety of
ways, including collecting and analyzing water, sediment, and benthic invertebrate
samples since 1972. Water quality samples have been collected monthly near the
mouth of May Creek at station 0440, which is located at the gaging station near the
bridge on Lake Washington Blvd and SE 80th St. Water quality monitoring data
indicates temperatures in May Creek near the project site average 10.2 degrees C
(King County, 2023), below the optimal salmon habitat temperature threshold of 12
C.
4.5.2 Water Quality
Sediments near the action area in May Creek are predominantly fine-grained,
organically enriched material. The average level of turbidity in May Creek within the
action area is low, based on King County Water Quality Monitoring (King County,
2023). Within the action area and watershed scales, baseline conditions for sediment
and turbidity are determined to be properly functioning.
King County Water Quality Monitoring identify the average mg/L of Total
Suspended Solids (TSS), Phosphorus, Ammonia, Nitrate, and Nitrogen to be below
the maximum measured in 50 years of monitoring (King County, 2023), though water
quality is determined to be poor (Kerwin, 2001).Within the action area and
watershed, baseline conditions for chemical and nutrient contamination are
determined to be not properly functioning.
4.5.3 Vegetative Conditions
The action area includes the freshwater habitat of May Creek which contains natural
cover such as overstory shade, LWD, and riparian vegetation, though riparian habitat,
LWD, hydrology, and pools are determined to be poor (Kerwin, 2001).
The majority of the site consists of undeveloped forest outside of the existing trail
alignment to the north of May Creek. Vegetation species noted throughout the study
area include an overstory of Douglas’ fir (Pseudotsuga menziesii), western hemlock
(Tsuga heterophylla), bigleaf maple (Acer macrophyllum), red alder (Alnus rubra),
black cottonwood (Populus balsamifera), and western red cedar (Thuja plicata), and
an understory of Pacific willow (Salix lasiandra), Sitka willow (Salix sitchensis),
evergreen huckleberry (Vaccinium ovatum), western skunk cabbage (Lysichiton
americanus), lady fern (Athyrium felix-femina), western common horsetail
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Renton, Washington Page 17 of 20
(Equisetum arvense) and non-native Himalayan blackberry (Rubus armeniacus)
Japanes/Bohemian knotweed (Reynoutria bohemica), among other plant species.
4.5.4 Habitat Values and Functions
A qualitative assessment of the project site indicate that it provides habitat value and
function due primarily to the riparian vegetation, terrestrial habitat, aquatic habitat,
and habitat complexity. These values and functions are outlined further in Mitigation
and Habitat Management Plan (WSP USA, 2023c).
4.6 HABITAT ALTERATIONS AND IMPACTS AND PROPOSED HABITAT
MANAGEMENT PROGRAM
The proposed mitigation is a comprehensive wetland and riparian enhancement
project that will include removing multiple infestations of invasive species and
installing native riparian vegetation. All of the site work except for the restoration of
temporary impacts will occur before or concurrently to construction of project. This is
outlined further in the Mitigation and Habitat Management Plan (WSP USA, 2023b).
Currently, the entire site is covered in infestations of Himalayan blackberry (Rubus
bifrons), hybrid knotweed (Fallopia x bohemica), English ivy (Hedera helix), English
holly (Ilex aquifolium), Portuguese laurel (Prunus lusitanica), among others. The City
of Renton has partnered with King County Healthy Lands Project to develop a multi-
year management plan to remove, treat, and manage these species. Additionally, the
City will have ongoing maintenance plans post-construction to manage invasives on-
site into the future. The Invasives species removal will constitute ~3.4 acres in total.
The City will replant native vegetation over disturbed uplands and wetlands post
invasive species management and before and during the construction of the project.
Vegetation will be replanted within the footprint of the crane laydown to the north of
May Creek. The areas to be planted includes ~3.28 acres. A temporary irrigation
system will be placed to help the plantings survive during the first few growing
seasons post restoration.
Planting will include native bare-root trees and shrubs installed through small
excavations dug by hand. All plants will be sourced locally and be from stocks native
to the Puget Sound lowlands. Plant materials will generally be in 1-gallon containers
or live stakes, but bare-root stock may be selected depending on timing and
availability.
The impacts of the proposed project are fully mitigated through on-site actions.
On-site mitigation activities will generate approximately 0.48 acres of mitigation
credits via enhancement of the wetlands and riparian buffers through invasive species
management and the planting of native trees, shrubs, and herbaceous vegetation.
Project Narrative WSP USA, 30902211.000 City of Renton, May Creek Trail South Soft Surface Trail and Bridge Project August 2024
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5.0 REFERENCES
City of Renton. 2023. Maps of Your Community. Accessed at
http://rp.rentonwa.gov/HTML5Public/Index.HTML?viewer=CORMaps
Accessed on Feb 21, 2023.
Davey Resource Group. Arborist Report – May Creek Trail South Project – Renton,
WA. December 3, 2022.
Kerwin, J. 2001. Salmon and Steelhead Habitat Limiting Factors Report for the Cedar
– Sammamish Basin (Water Resource Inventory Area 8). Washington
Conservation Commission, Olympia.
King County. 2023. King County Water Quality Monitoring.
https://green2.kingcounty.gov/streamsdata/watershedinfo.aspx?Locator=0440.
Accessed February 20, 2023.
King County. 2001. Final Adopted May Creek Basin Action Plan, April 2001.
https://your.kingcounty.gov/dnrp/library/2001/kcr726.pdf. Accessed February
20, 2023.
PanGeo. 2023. Geotechnical Report – May Creek Trail South Project. March 2023.
Richter, K.O., and A.L. Azous. 1997. Amphibian distribution, abundance, and habitat
use. In: Azous, A.L., and Horner, R.R. (eds.), Wetlands and Urbanization –
Implications for the Future, Final Report. Puget Sound Wetlands and
Stormwater Management Research Program, Washington State Department of
Ecology, Olympia, King County Water and Land Resources Division, Seattle,
Washington, and University of Washington, Seattle, Washington.
National Oceanic and Atmospheric Administration Fisheries Service (NOAA
NMFS). 2023. ESA Threatened & Endangered Listings, available at
https://www.fisheries.noaa.gov/species-directory/threatened-endangered.
Accessed February 15, 2023.
U.S. Fish and Wildlife Service (USFWS). 2023. Information for Planning and
Consultation. http://ecos.fws.gov/ipac/. Accessed February 17, 2023.
Washington State Department of Fish and Wildlife (WDFW). 2023. Priority Habitats
and Species List—PHS on the Web. http://wdfw.wa.gov/mapping/phs/.
Accessed February 15, 2023.
Washington State Department of Fish and Wildlife (WDFW). 2023a. WDFW
SalmonScape database, available at
https://apps.wdfw.wa.gov/salmonscape/map.html. Accessed April 14, 2019.
Washington Department of Fish and Wildlife (WDFW). 2023b. WDFW Threatened
and endangered species listing, available at https://wdfw.wa.gov/species-
habitats/at-risk/listed. Accessed February 15, 2023.
Project Narrative WSP USA, 30902211.000 City of Renton, May Creek Trail South Soft Surface Trail and Bridge Project August 2024
Renton, Washington Page 19 of 20
Weitkamp, D.E., G.T. Ruggerone, L. Sacha, J. Howell, and B. Bachen. 2000. Factors
Affecting Chinook Populations – Background Report. City of Seattle, Seattle,
Washington.
WSP USA. 2024a. Wetlands and Waterbodies Delineation and Assessment Report –
May Creek Trail South Project. April 2024.
WSP USA. 2024b. Mitigation and Habitat Management Plan – May Creek Trail
South Project. August 2024.
WSP USA. 2024c. Drainage Report – May Creek Trail South Project. September
2024.
WSP USA. 2024d. Biological Assessment – City of Renton May Creek Trail South
Project. August 2024.
Wydoski, R.S., and R. Whitney. 2003. Inland Fishes of Washington. American
Fisheries Society, Bethesda, Maryland, and University of Washington Press,
Seattle.
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6.0 LIST OF ACRONYMS AND ABBREVIATIONS
Ecology Washington State Department of Ecology
ESA Endangered Species Act
LWD large woody debris
MHHW mean higher high water
MLLW mean lower low water
MMPA Marine Mammal Protection Act
NE no effect
NOAA Fisheries National Oceanic and Atmospheric Administration Fisheries Service
NWP Nationwide Permit OHWM ordinary high water mark
PHS Priority Habitat and Species
RCW Revised Code of Washington
RMC Renton Municipal Code
SMP Shoreline Management Program
SSDP Shoreline Substantial Development Permit
USACE U.S. Army Corps of Engineers
USFWS U.S. Fish and Wildlife Service
WDFW Washington Department of Fish and Wildlife
APPENDIX A
60% DESIGN PLAN SET