HomeMy WebLinkAboutR-417986INTRODUCTION
The subject property is composed of five King County tax parcels (3345700015,
3345700016, 3345700017, 3345700018, 3345700020). The site is approximately
10.1-acres, located at and adjacent to 8314 110th PI SE and 4130 Lincoln Ave NE in
the City of Renton, Washington (Section 32, Township 24N, Range 5E, W M.). Access
is via a driveway from Lincoln Ave NE.
d'
1
6
d'
EX. DITCH
WETLAND A
TO BE FILLED.
1,585 SF
WETLAND B
CATEGORY IV
50' BUFFER
UTILITY EASEMENT
Scale 1" = 100'
0 50 100 150 200
WETLAND
WETLAND ENHANCEMENT
BUFFER AVERAGING
/
(REDUCTION)
BUFFER AVERAGING
(ADDITION)
BUFFER IMPACT
WETLAND IMPACT
BUFFER ENHANCEMENT
A 19r'JMf1V I ft A AT
PROPERTY BOUNDARY
RIGHT-OF-WAY
— — STREAM
APPROX.STREAM
BOUNDARY
---- STANDARD BUFFER
------------ 75% OF STANDARD BUFFER
FINAL BUFFER/PERMANENT
FENCE/SIGNS
15' BUFFER STRUCTURE
SETBACK
APPROXIMATE LOCATION
OF TRAIL TO CONNECT TO
CITY OF NEWCASTLES TRAIL
ALONG NE 43RD ST RIGHT-OF-WAY
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WETLAND C
CATEGORY IV
50' BUFFER
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APPROXIMATE
LOCATION OF
STREAM CROSSING
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I I TYPE NP
75' BUFFER
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kETLAND D
AATEGORY IV
50'\BUFFER
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PROPOSED TRAIL
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UNOPENED \\
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OF 112TH AVE SE \\
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STEEP SLOPE AREA \
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BUFFER \
ENHANCEMENT \\
AREA A \
6,788 SF \
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STREAM S WETLAND C \\
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BUFFER IMPACT
401 SF
BUFFER
ENHANCEMENT
AREA B
781 SF
BUFFER IMPACT
380 SF
STREAM S
BUFFER REDUCTION
2,635 SF
STREAM S
BUFFER ADDITION
2,695 SF
SITE DESCRIPTION
The subject property is located within the May Creek sub -basin of the Cedar
River/Lake Washington Watershed (WRIA 8). Lake Washington is approximately 3,000
feet west of the subject property. Surrounding land use is mixed, including residential,
commercial, and industrial uses; with 1-405 approximately 1,100 feet to the west. The
site is partially developed; in the south, there are multiple single-family residences and
associated infrastructure, while the northern portion contains naturally vegetated
pasture and forested areas. Topography slopes steeply to the west, and, according to
King County iMap, is underlain by high erosion hazard areas, with slopes in excess of
20 percent.
Four wetlands (Wetlands A through D) and one stream (Stream S) were identified
within the investigation area.
Pursuant to Renton Municipal Code (RMC), on -site wetlands were classified under the
Washington State Wetland Rating System for Western Washington. 2014 Update
(Hruby 2014). Wetlands A through D are classified as Category IV wetlands. Per RMC
(7)(a) Stream S was classified based on the WAC 222-16-030. As such, Stream S is
classified as a Type Np Stream. Per 4-3-050(G)(2), Category IV wetlands typically
receive 50-foot buffers (when adjacent to non -low impact land uses) and Type Np
streams typically receive 75-foot buffers.
In addition, geological hazards were identified on -site by the geotechnical engineer,
Terra Associates, Inc. Geological hazards identified include protected slopes, high
erosion hazard area, and low seismic hazard area. Per RMC 4-3-050G(2), protected
slopes require a 15 foot structure setback.
PROJECT DESCRIPTION
The applicant is proposing to develop a 56-lot residential development and associated
infrastructure. To accommodate this development, the applicant will do a combination of
buffer width averaging and wetland/buffer impacts, to be mitigated for on -site. As a result
of required frontage improvements and stormwater infrastructure, the applicant will
permanently impact the entirety of Wetland A (and a portion of an associated ditch),
totaling 1,585 square feet, and a small portion (240 square feet) of Wetland B's buffer. In
addition, the applicant will utilize buffer averaging to accommodate the proposed
development adjacent to Wetland B, Wetland D, and Stream S.
As mitigation for the impacts, the applicant is proposing a combination of on -site and
off -site mitigation. A portion of the compensation (meeting City of Renton requirements)
for Wetland A impacts will be provided by enhancing the entirety of the on -site portions
of Wetlands B and D (totaling 4,865 square feet). This exceeds the 3.1 (enhancement to
impact) ratio for Category IV wetlands, per RMC 4-3-050(J)(4)(c).
The aforementioned impact to the buffer of Wetland B will be mitigated for via
enhancement of 700 square feet of buffer located between Wetland B and Lincoln Ave
NE (exceeding the 1.1 mitigation to impact ratio required by RMC 4-3-050(J)(4)(d)). To
accommodate Stream S buffer width averaging, the applicant proposes to enhance a
6,788 square feet of stream buffer, per RMC 4-3-050(1)(2)(b)(v).
As part of the proposed development the City of Renton is requiring an on -site and
off -site trail to connect the development to the City of Newcastle's pedestrian trail
located along the NE 43rd Street right-of-way, north of the subject property. The off -site
portion of the trail will be located within the unopened right-of-way of 112th Avenue SE,
that parallels the eastern property boundary. The trail shall be 5 feet wide, with the
majority consisting of wood chips underlain with filter fabric, and will be field fit to avoid
trees. The trail will cross portions of wetland, stream, and buffer. Per RMC 4-3-050C(3)
and RMC 4-3-050C(4), trails are exempt and allowed within critical areas and their
associated buffers as long as they meet certain requirements. The portion of trail
crossing the wetland will consist of a boardwalk and supported by pin piles. The slatted
decking of the boardwalk and grated top of the dock will allow precipitation to move
through the structure. This design minimizes impacts to the wetland and aquatic area
and avoids any fill or grading within the wetland. Disturbance within the wetland will be
limited to vegetation impacted for boardwalk installation. This portion of the trail will
impact approximately 134 square feet of vegetation associated with Wetland D. To
mitigate for any temporal loss of vegetation from installation of the boardwalk, buffer
enhancement of a portion of Wetland D's on -site buffer is proposed at a 3.1
enhancement to impact ratio. The bridge proposed over Stream S will be approximately
6 feet wide and will consist of concrete slabs and metal railings. The crossing will be
consistent with WDFW stream crossing guidelines.
PROJECT MONITORING PROGRAM
Requirements for monitoring project:
1. Initial compliance/as-built report
2. Site inspection (twice per year) for five years
3. Annual reports (one report submitted during each monitored year)
Purpose for Monitoring
The purpose for monitoring this mitigation project shall be to evaluate its success.
Success will be determined if monitoring shows at the end of five years that the
definitions of success stated below are met. The property owner shall grant access to
the mitigation area for inspection and maintenance to the contracted landscape and/or
wetland specialist and City of Renton during the monitoring period or until the project is
evaluated as successful.
Monitoring
Monitoring shall be conducted twice annually for five years in accordance with the
approved Mitigation Plan. The monitoring period will begin once the City receives
written notification confirming the mitigation plan has been implemented and City staff
inspects the site and issues approval of the installation.
Vegetation Monitoring
Sampling points or transects will be established for vegetation monitoring and photo
points will be established from which photos will be taken throughout the monitoring
period. Permanent sampling points must be identified on the mitigation site plans in the
first monitoring report (they may be drawn on approved plans by hand). Each sampling
point shall detail herbaceous, shrub, and tree coverage. Monitoring of vegetation
sampling points shall occur once per monitored year.
Wetland Hydrology Monitoring
To ensure that wetland hydrology is not impacted by the development, the wetland
boundaries will be reviewed during the spring monitoring visit of each monitored year. If
it appears that any existing wetland areas are no longer saturated or inundated for
sufficient duration to support wetland conditions, those areas will be demarcated in the
field and depicted on a map. Additional mitigation may need to be provided, as
described in the contingency plan in Section 15, below.
MONITORING REPORT CONTENTS
Monitoring reports shall be submitted by December 31 of each year during the
monitoring period. As applicable, monitoring reports must include descriptions / data
for:
1. Site plan and vicinity map
2. Historic description of project, including date of installation, current year of
monitoring, restatement of mitigation/restoration goals, and performance
standards
3. Plant survival, vigor, and areal coverage for every plant community (transect
or sampling point data), and explanation of monitoring methodology in the
context of assessing performance standards
4. Wetland and buffer conditions, e.g., surrounding land use, use by humans,
and/or wild and domestic creatures
5. Observed wildlife, including amphibians, avians, and others
6. Assessment of nuisance / exotic biota and recommendations for management
7. Color photographs taken from permanent photo -points that shall be depicted
on the monitoring report map
PROJECT SUCCESS & COMPLIANCE
Criteria for Success
Upon completion of the proposed mitigation project, an inspection by a qualified
biologist will be made to determine plan compliance. A compliance report will be
supplied to the City of Renton within 30 days after the completion of planting. A
landscape professional or wetland professional will perform condition monitoring of the
plantings in the spring and fall of each monitored year. A written report describing the
monitoring results will be submitted to the City after each site inspection of each
monitored year. Final inspection will occur five years after completion of this project.
The contracted consultant will prepare a report as to the success of the project.
Definition of Success
The planting areas shall meet the following performance standards:
a) End of Year 1
• 100 percent survival of newly planted species and
• Less than 10 percent cover of weedy/invasive species
b) End of Year 2
• 80 percent survival of newly planted species
• Less than 10 percent cover of weedy/invasive species
c) End of Year 3
• At least 50 percent native vegetation coverage within the mitigation areas*
• Less than 10 percent cover of weedy/invasive species
d) End of Year 5
• At least 80 percent aerial cover of native woody plant species*,
• Less than 10 percent cover of weedy/invasive species.
*Volunteering native species may be included in the aerial cover calculations.
The species mix should resemble that proposed in the planting plans, but strict
adherence to obtaining all of the species shall not be a criterion for success.
PROJECT NOTES
Pre -Construction Meeting
Mitigation projects are typically more complex to install than to describe in plans.
Careful monitoring by a wetland professional for all portions of this project is strongly
recommended. Construction timing and sequencing is important to the success of this
type of project. There will be a pre -construction meeting on this site between the
Permittee, the consulting wetland professional, and laborers. The objective will be to
verify the location of erosion control facilities, verify the location of mitigation areas, and
to discuss project sequencing.
Inspections
A wetland professional shall be contracted to periodically inspect the mitigation
installation described in this plan. Minor adjustments to the original design may be
necessary prior to and during construction due to unusual or hidden site conditions. A
City of Renton representative and/or the consulting professional will make these
decisions during construction.
CONTINGENCY PLAN
If 20% of the plants are severely stressed during any of the inspections, or it appears
20 percent may not survive, additional plantings of the same species may be added to
the planting area. Elements of a contingency plan may include, but will not be limited
to: more aggressive weed control, pest control, mulching, replanting with larger plant
material, species substitution, fertilization, soil amendments, and/or irrigation.
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Photo points
No less than four permanent photo points will be established within the mitigation
areas. Photographs will be taken from these points to visually record condition of the
mitigation areas. Photos shall be taken annually between May 15 and September 30
(prior to leaf drop), unless otherwise specified.
DEVELOPMENT ENGINEERING + r"1
msippo 05/10/2022 W
R417986,
98 of 107