HomeMy WebLinkAboutEx 11_Analysis and Mitigation Plan.pdf
Critical Area Impact Analysis & Mitigation Plan
for
55XX N.E. 10th St.
Renton, Washington 98059
Tax Parcel No. 1023059360
SE Quarter of Section 10, Township 23 N, Range 5 E
City of Renton PRE22-000219
Prepared for:
Yan Lifshaz
425-443-6129
ylifshaz@comcast.net
Dated:
March 22, 2023
Prepared by:
Jeffery S. Jones, Wetland Scientist & Wildlife Biologist
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Table of Contents
1.0 Project Description ................................................................................................................... 1
2.0 Parcel & Study Area Summary ................................................................................................ 1
3.0 Analysis of Critical Area Impacts ............................................................................................ 2
4.0 Mitigation Sequencing ............................................................................................................. 3
5.0 Vegetative Enhancement ......................................................................................................... 4
6.0 Monitoring ............................................................................................................................... 5
6.1 Vegetation Monitoring ......................................................................................................... 5
6.2 Photo points ......................................................................................................................... 5
6.3 Monitoring Reports ............................................................................................................... 5
6.4 Deficiencies .......................................................................................................................... 5
6.5 Contingency Plan ................................................................................................................. 5
6.0 Performance Standards ............................................................................................................ 6
6.0 Protection Mechanisms ............................................................................................................ 6
7.0 No Net Loss ............................................................................................................................. 6
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1.0 Project Description
The applicants propose to construct a single-family residence within an aquatic buffer and a
wetland buffer. The proposed house footprint is 1,274 square feet, plus a 128.90 square foot
porch and 342.74 square foot cover deck. The property is 0.36 acre vacant lot. The entire tax
parcel is encumbered with wetland, stream, and their associated buffers. To minimize impacts
the house will be located northeast corner of the property, the minimum side setback, and a
proposed reduced front setback of 20 feet. There are no structures or impervious surfaces that
will be removed. The land use review process for unavoidable critical area buffer impacts is a
Critical Area Variance.
2.0 Parcel & Study Area Summary
Site Address: Unassigned
Zip Code: 998059
King County Tax Id No.: 102306-9360
¼ Section, Section, Township, Range:
NE quarter, Section 10, Township 23 North,
Range 5 East, of the Willamette Meridian.
Latitude/Longitude: Lat. 47.49903, Long. -122.14565
Parcel Size: 11,372 sf, 0.26 acres
Water Resource Inventory: Cedar Sammamish WRIA 8
Drainage Basin: May Creek
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3.0 Analysis of Critical Area Impacts
The proposed building envelope is 5,274.88 square feet (sf). The house will be placed a reduced
20-ft front setback, 7.5-foot side setback, and provide a 15-foot BSBL between the remaining
wetland buffer and the proposed structure. Retaining walls and other types of structures are not
allowed in the BSBL. The required frontage improvements including curb, gutter, sidewalk, and
planting strips, is 2,382.13 sf. There is also 561.69 sf of driveway impact and 41.77 sf of
walkway impact, outside of the BSBL. The total critical area buffer impact is 8,260 square feet.
Summary of Impacts
Impacts - Permanent Wetland SF Buffer SF
Building Envelope 0 5,274.88
Frontage Improvement in ROW 0 2,382.13
Driveway Outside of BSBL 0 561.69
Walkway Outside of BSBL 0 41.77
Total Proposed Impacts 0 8,260.47
Impacts - Temporary Wetland SF Buffer SF
Enhancement Wetland Buffer 0 8,260
Total 0 8.260
Impacts - Future Wetland
Buffer SF
Outside of
the Wetl.
Buffer SF
None 0 0
The impacted area is dominated by dense Himalayan blackberry understory with a few trees
shown in the arborist report. The tax parcel above the wetland boundary was previously cleared,
as evidenced by the absence of native vegetation, and dominance of Himalayan blackberry.
The tax parcel is identified as an erosion hazard area. Slopes are 20% with sandy soils. Best
management construction practices, including Temporary Erosion and Sediment Control Plan
(TESCP) measures, will be used. A Geotech study has been submitted. The civil engineer has
prepared a stormwater drainage plan that meets the current stormwater design manual and
Geotech recommendations.
Utilities are available in the NE 10th St. ROW. City water and sewer are available, so onsite
septic system and water well are not needed.
The occurrence of wildlife species is closely related to the plant community, stand condition, and
presence of special or unique habitats. Many wildlife species are associated with forested
wetlands in Western Washington. Honey Creek is a Type F stream. The removal of non-native
invasive plant species and reestablishment of native plant community in the buffer will improve
wildlife habitat and reduce the likelihood of soil erosion and sediment movement into the stream.
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4.0 Mitigation Sequencing
RMC 4-3-050L MITIGATION, MAINTENANCE AND MONITORING:
b. Mitigation Sequencing: If alterations to critical areas are proposed for a non-exempt activity,
the applicant shall evaluate alternative methods of developing the property using the following
criteria in this order and provide reasons why a less intrusive method of development is not
feasible. In determining whether to grant permit approval pursuant to RMC 4-3-050C, a
determination shall be made as to whether the feasibility of less intrusive methods of development
has been adequately evaluated and that less intrusive methods of development are not feasible.
i. Avoiding the impact altogether by not taking a certain action or parts of an action (usually by
either finding another site or changing the location on the site).
The entire property is encumbered in critical area and critical area buffer, including a Category II
wetland, wetland buffer, and Honey Creek stream buffer which overlaps the wetland and wetland
buffer. Impacts to critical area buffers are unavoidable without denying all use of the property.
ii. Minimizing adverse impacts by limiting the magnitude of the action and its implementation,
by using appropriate technology, or by taking affirmative steps, such as project redesign,
relocation, or timing, to avoid or reduce impacts.
The proposed single-family residence is located to minimize buffer impacts. The proposed
house will be located as far from the wetland boundary as possible, is the minimum structure
side setback, a front setback reduced from 30 feet to 20 feet, and provides a 15-foot BSBL.
iii. Rectifying adverse impacts to wetlands, Wellhead Protection Areas, flood hazard areas,
and habitat conservation areas by repairing, rehabilitating, or restoring the affected
environment to the historical conditions or the conditions existing at the time of the initiation of
the project.
The compensation for wetland buffer impacts will be vegetation enhancement of remaining
wetland buffer at slightly greater than a 1:1 ratio, and removal of non-native invasive plant
species. Vegetation enhancement restores the critical area buffer habitat functions. The
proposed building envelope is not a flood hazard area or wellhead protection area.
iv. Minimizing or eliminating the hazard by restoring or stabilizing the hazard area through
engineered or other methods.
Temporary erosion control measure will be implemented according to an approved TESCP plan.
The TESCP plan will incorporate the drainage plan and recommendations from the Geotech
study.
v. Reducing or eliminating the adverse impacts or hazard over time by preservation and
maintenance operations over the life of the action.
The remaining critical areas will be placed in a native growth protection easement. There will be
a 5 years maintenance and monitoring program, which may be extended up to 10 years.
vi. Compensating for adverse impacts to wetlands, Wellhead Protection Areas, flood hazard
areas, and habitat conservation areas by replacing, enhancing, or providing substitute
resources or environments.
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Compensation for loss of critical area buffer is vegetative enhancement of an equal square
footage of buffer.
vii. Monitoring the hazard or other required mitigation and taking remedial action when
necessary.
A minimum five year monitoring program for mitigation is required. Annual monitoring reports
may provide recommendations for remedial actions.
5.0 Vegetative Enhancement
Erosion control fencing will be installed before any clearing and grading of the site. Himalayan
blackberry will be removed with an excavator and the soil surface will be cleaned of woody
debris to prepare the soil surface for planting. Existing native trees will be left in place. Any
large woody debris will be retained onsite and distributed across the buffer. Native plants will be
installed according to the schedule below.
PLANT MATERIALS SCHEDULE (8,260 SF)
Common Name Sci. Name Size/Condition
Plant
Qty.
Douglas fir Pseudotsuga menziesii 2 gal 14
Western red cedar Thuja plicata 2 gal 14
Big-leaf maple Acer macrophyllum 2 gal 14
Red alder Alnus rubra 1 gal 40
Total Trees 82
Vine maple Acer circinatum 1 gal 12
Beaked hazelnut Corylus cornuta 1 gal 12
Red elderberry Sambucus racemosa 1 gal 12
Pacific ninebark Physocarpus capitatus 1 gal 12
Salmonberry Rubus spectabilis 1 gal 48
Red huckleberry Vaccinium parcifolium 1 gal 12
Sword fern Polystichum munitum 1 gal 30
Tall Oregon grape Mahonia aquifolium 1 gal 30
Salal Gaultheria shallon 1 gal 30
Total Shrubs & Groundcovers 258
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6.0 Monitoring
6.1 Vegetation Monitoring
Monitoring shall be conducted annually for 5 years and may be extended by the city up to 10
years if performance standards are not met.
Belt-transects and plots will be established for vegetation monitoring, and photo-points
established from one end of each transect and one per plot. No less than (1) one transect and (3)
three plots will be established in each enhancement area. Permanent plot location(s) must be
identified on mitigation/restoration site plans in the first monitoring report (they may be drawn
on approved mitigation/restoration plans by hand). Monitoring of vegetation plots shall occur
annually between August 1 and September 30 (prior to leaf drop), unless otherwise specified.
6.2 Photo points
No less than three (3) permanent photo point per plot and transect will be established within each
mitigation/restoration area. Photographs will be taken from these points to visually record the
condition of the mitigation/restoration area. Photos shall be taken annually between August 1
and September 30 (prior to leaf drop), unless otherwise specified.
6.3 Monitoring Reports
Monitoring reports shall be submitted by December 31 of each year during the monitoring
period. As applicable, monitoring reports must include description/data for:
i. Site plan and location map
ii. Historic description of project, including date of installation, current year of monitoring,
restatement of mitigation/restoration goals, and performance standards
iii. Plant survival, vigor, and aerial coverage from every plant community (transect data),
and explanation of monitoring methodology in the context of assessing performance standards
iv. Slope condition, site stability, any structures, or special features
v. Buffer conditions, e.g., surrounding land use, use by humans
w. Observed wildlife
x. Assessment of nuisance/exotic biota and recommendations for management
viii. Soils, including texture, Munsell color, rooting and oxidized rhizoshperes
ix. Receipts for off-site disposal of any dumping, weeds, or invasive plants
x. Receipts for any structural repair or replacement
xi. 4"x6" color photograph taken from permanent photo-points as shown on
Monitoring/Restoration plan.
xiii. Summary of maintenance and contingency measures proposed for next season and
completed for past season.
6.4 Deficiencies
Any deficiency discovered during any monitoring or inspection visit must be corrected within 60
days of approval by the City of Renton.
6.5 Contingency Plan
Should any monitoring report reveal the mitigation has failed in whole or in part, and should that
failure be beyond the scope of routine maintenance, a Contingency Plan will be submitted. The
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Contingency Plan may range in complexity from a list of plants substituted, to cross-sections of
proposed engineered structures. Once approved, it may be installed, and will replace the
approved mitigation/restoration plan. If the failure is substantial, the City of Renton may extend
the monitoring period for that mitigation.
6.0 Performance Standards
Plant survival and cover standards are established to measure mitigation success as follows:
Performance Standards
Yr. 1 Yr. 2 Yr. 3 Yr. 4 Yr. 5
Vegetative Cover* >10% >15% >20% >30% >50%
Plant Survival 100% >95% >90% >85% >80%
*Includes beneficial native plants in that category that are naturally recruiting volunteers
Less than 10% invasive vegetation during any monitoring event.
6.0 Protection Mechanisms
Critical area signs posted on the site will provide a public notification of the presence of critical
areas. A critical area notice on-title will be recorded at King County Records. The notice on-
title will include a site plan that clearly identifies the location of critical areas and their buffers
that cannot be disturbed. During the application process, a public notice will be provided to
property owners as per the city public notice requirements. If public notice is not included with
the notice of application, then instead it will be given at the time of the SEPA determination.
A financial guarantee will be provided to ensure performance install, maintenance, monitoring,
and contingencies. The amount of the guarantee will be determined using the King County
Mitigation Bond Quantity worksheet. The city also requires the owner to sign an access release
form. The financial guarantee will not be released until the final mitigation monitoring is
approved.
In order to ensure no loss of critical area functions and values, development permits shall not be
issued prior to installation and acceptance of all required mitigation unless a surety device in an
amount of three hundred percent (300%) of the mitigation installation contract amount is
provided to the satisfaction of the City (RMC 4-3-050L.f.)
7.0 No Net Loss
“No net loss” is a federal, state, and local jurisdiction goal that the further loss of wetlands and
wetland functions will not occur. “No net loss” is not defined in the Renton Municipal Code
definitions section. Governor Booth Gardner Executive Order 89-10 states, “Section 1. It is the
interim goal of my administration to achieve no overall net loss in acreage and function of
Washington’s remaining wetland base. It is further the long-term goal to increase the quantity
and quality of Washington’s wetlands resource base.”
The proposed project will not result in loss of wetland acreage. Although there will be a loss in
the critical area buffer square footage, the buffer functions and values will be improved by
reestablishing and enhancing a native plant community. Wetland buffer enhancement will be
implemented prior to the granting of occupancy for the single-family residence. Mitigation
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activities shall be timed to occur in the first spring or fall planting season following the issuance
of permits.
NORTHEnvironmental ConsultantsPROJECT:
CLIENT:
1"=40'
SCALE
DRAWN BY:
J. Jones
CHECKED BY:
DESIGNED BY:
3/22/2023
1 of 5
SHEET APPROVED BY:
DATE:
CONSULTANT:
Wetlands, Streams, and Wildlife
PO Box 1908 Issaquah, Washington 98027 253 905-5736 SCALE: 1" = 40'J. S. Jones and Associates, Inc.
Yan Lifshaz
PO Box 53046, Bellevue, WA 98015
425-443-6129/ylifshaz@comcast.net
NO.DATE BY REVISIONAPPLICANTYan LifshazPO Box 53046Bellevue, WA 98015425-443-6129ylifshaz@comcast.netCIVIL ENGINEER OR SURVEYOR:Matthew J. Haringa, P.E.PrincipalInterlaken Engineering and Design, PLLCSeattle, WA206-470-9572www.interlakenengineering.comENVIRONMENTAL CONSULTANT:Jeffery JonesJ. S. JONES AND ASSOCIATES, INC.PO Box 1908Issaquah, WA 98027253-905-5736jeff.jsjones@comcast.netVICINITY MAPNOT TO SCALELifshaz Wetland Buffer Variance
551X NE 10th St., Renton, WA
King County Tax Parcel No. 102305-9360 Bretzke Single-family Residence Critical Area Variance551X NE 10th St., Renton, WAKing County Tax Parcel No. 102305-9360NORTH