REVIEWED PLN_RESUB1 BLD2021-0758+MITIGATION+7.13.2021_8.45.15_AM+2296849BLD2021-0758
RESUB
Jul 13 2021 ,
CITY OF EDMONDS
DEVELOPMENT SERVICES
DEPARTMENT CONFLUENCE
ENVIRONMENTAL COMPANY
146 N Canal St, Suite 111 • Seattle, WA 98103 • www.confenv.com
817 7t" Avenue North
STREAM BUFFER ENHANCEMENT PLAN
Prepared for:
Max Gruici
817 7t" Avenue North
Edmonds, WA 98020
Authored by:
Irene Sato, PWS
Confluence Environmental Company
July 9, 2021
146 N Canal St, Suite 111 • Seattle, WA 98103 • www.confenv.com
817 711 Ave N Stream Buffer Enhancement Plan
TABLE OF CONTENTS
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ENVIRONMENTAL COMPANY
1.0 INTRODUCTION...................................................................................................................................................1
1.1 Background..............................................................................................................................................1
1.2 Proposed Development............................................................................................................................3
1.3 Compliance with ECDC 23.90.040...........................................................................................................3
2.0 PROPOSED ENHANCEMENT PLAN...................................................................................................................5
2.1 Goals and Objectives...............................................................................................................................7
2.2 Planting Plan............................................................................................................................................7
2.3 Maintenance.............................................................................................................................................9
2.4 Performance Standards............................................................................................................................9
2.5 Monitoring.................................................................................................................................................9
2.6 Contingency Plan...................................................................................................................................10
3.0 FINANCIAL GUARANTEES...............................................................................................................................10
4.0 REFERENCES....................................................................................................................................................10
TABLES
Table 1. Mitigation for Permanent Stream Buffer Impacts.............................................................................................4
Table2. Planting Schedule............................................................................................................................................7
Table 3. Summary of Success Criteria...........................................................................................................................9
FIGURES
Figure 1. Delineated Stream and Standard Buffer.........................................................................................................2
Figure 2 -Existing condition of stream buffer to be impacted.........................................................................................3
Figure 3- Looking south at stream buffer to be enhanced..............................................................................................5
Figure 4—Looking north at stream buffer to be enhanced. Stream is in the left corner of photo (foreground is
constructed stormwater channel).....................................................................................................................6
Figure 5. Areas of Stream Enhancement.......................................................................................................................8
APPENDICES
Appendix A— King County Critical Areas Bond Worksheet
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817 Th Ave N Stream Buffer Enhancement Plan
1.0 INTRODUCTION
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The purpose of this report is to present a stream buffer enhancement plan for unavoidable
impacts to a stream buffer from the construction of a second story deck on a single-family
residence at 817 Th Ave N, Edmonds, WA (tax parcel number 27032400202200) (Figure 1). This
plan describes how the project meets the requirements per Edmonds Community Development
Code (ECDC) 23.90.040.D4.a.iv, 23.40.110, 23.40.120, 23.40.130 and 23.90.040.D.2.
1.1 Background
On March 25, 2021 Confluence Environmental Company (Confluence) conducted a site visit and
prepared a Critical Area Report (Confluence 2021). The City has reviewed the building permit
application (Plan check BLD2021-7058) and has requested mitigation for impacts to the stream
buffer. This enhancement plan is based on findings from the site visit and report.
Shell Creek is a Type F stream that flows north across the property near the west boundary. The
stream eventually outlets into Puget Sound approximately 0.3 mile north of the property. Per
ECDC this stream has a 100-foot buffer. Figure 1 shows the stream and buffer.
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817 7th Ave N Stream Buffer Enhancement Plan
0
Footbridge
AL Ir•; A
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Z.
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N 0 Parcel27032400202200
ACONFLUENCE — Shell Creek OHWM
LNVIMNMONTAL COMPANY
0 25 Drainage Feature
Feet Stream Buffer - 100 ft
Meters
0 5 0 Proposed Deck
26'
15'
31
7
CONENVIRONMENTAL COMPANY
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k
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817 Th Ave N Stream Buffer Enhancement Plan
1.2 Proposed Development
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The existing single-family residence is approximately 107 feet away from the stream. The
proposal is to construct a 450 square foot second story deck. Approximately 246 square feet of
the deck is within the stream buffer. The impacted buffer is lawn and bare ground and provides
poor stream buffer functions (Confluence 2021). Figure 2 shows the existing condition of the
buffer.
Figure 2 -Existing condition of stream buffer to be impacted.
1.3 Compliance with ECDC 23.90.040
The building permit review letter from the City dated June 11, 2021 outlined 3 options to
address impacts to the stream buffer. This plan seeks compliance under Option #1. See excerpt
from the letter below in italics.
Reduced Stream Buffer Options:
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817 Th Ave N Stream Buffer Enhancement Plan
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1. The proposal includes a portion of new footprint that is located within the 100 foot stream buffer but is
not more than 300 square feet of structure addition within the inner 50% of the standard stream buffer
width. Pursuant to ECDC 23.90.040.D.4.a.iv additions that increase the footprint of development or
impervious surfacing may be permitted provided that a buffer enhancement plan is provided at a
minimum three -to -one (3:1) ratio (enhancement -to -impact). Using this option, you will need to show the
stream buffer on the site plan, provide the area of the deck and stairs that is located within the standard
buffer and provide mitigation that is 3 times the area of the proposal within the buffer. For example, if the
proposed deck and stairs located within the standard buffer is 100 square feet then the mitigation plan
will need to be 300 square feet of area. The mitigation area should be provided close to the stream
(preferably in an area with bare soil) and should include native vegetative species.
This project proposes to add a deck to a legally constructed structure with 246 square feet of
structure in the stream buffer and will mitigate by enhancing 738 square feet of stream buffer to
provide a 3:1 enhancement ratio. Table 1 outlines the impacts and mitigation proposed.
Table 1. Mitigation for Permanent Stream Buffer Impacts
Per ECDC 23.90.040.D4.a.iv
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817 Th Ave N Stream Buffer Enhancement Plan
2.0 PROPOSED ENHANCEMENT PLAN
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Per ECDC 23.90.020.D4 this proposed buffer enhancement will provide a net benefit to the
functions and values of the stream buffer.
Both banks of Shell Creek are largely unvegetated and consist of bare ground. Four trees,
including western red -cedar (Thuja plicata) and an unidentified non-native species, are located
approximately 10 feet from the right (east) bank. There are 4 large conifers on the west side of
the stream. No overhanging shrubby vegetation is present along the banks and there is no
understory below the tree canopy. The remainder of the 100-foot buffer between the house and
the stream consists of lawn and 3 large conifers (2 Douglas -fir [Pseudotsuga menziesh] and 1
ornamental, non-native tree). Figures 3 and 4 show the existing condition of the proposed
stream buffer to be enhanced.
Figure 3 - Looking south at stream buffer to be enhanced
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817 Th Ave N Stream Buffer Enhancement Plan
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Figure 4 - Looking north at stream buffer to be enhanced. Stream is in the left corner of photo
(foreground is constructed stormwater channel).
The relative lack of riparian vegetation is indicative of a low -functioning stream buffer. Riparian
vegetation is essential in providing shade for salmonids and other resident fish, erosion
reduction, a source of large woody debris which increases habitat complexity within the stream,
vital nutrients from associated organic matter, and a food source for aquatic and terrestrial
insects that feed on such organic matter (Knight 2009). These functions are largely absent within
the stream buffer in its current condition within the property.
Since there are approximately 8 large conifers that provide an established canopy over the
stream enhancement areas, trees are not proposed to be planted. Most of the plantings will be
shrubs. The shrub enhancement will create wildlife cover and habitat. The enhancement area is
bare ground; therefore, groundcover plantings are proposed to provide a more complex and
stratified buffer.
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817 711 Ave N Stream Buffer Enhancement Plan
2.1 Goals and Objectives
Mitigation Goal
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■ Restore a vegetated riparian buffer along Shell Creek to create a more natural
functioning buffer that provides more water quality protection, more wildlife habitat
and enhances fish habitat.
Mitigation Objective
■ Enhance 738 square feet of stream buffer by planting native shrubs and ground cover.
■ Add 5 plant species to the riparian buffer to provide diversity.
Plants will be installed during the Fall of 2021 and completed by October 31, 2021.
2.2 Planting Plan
Table 2 shows the proposed planting schedule for 738 sq. ft. of mitigation. This will be divided
into 2 369 square foot areas: 1 on the north side of the property and 1 on the south side of the
property. Figure 5 shows the enhancement areas.
Table 2. Planting Schedule
SpacingCommon Name Scientific Name Container
Quantity*
Size OC)
Stream Buffer Enhancement North Side (approximately 369 square feet)
Salal
Gaultheria shallon
1 gallon
3
10
Red -flowering currant
Ribes sanguineum
1 gallon
3
10
Pacific rhododendron
Rhododendron
macro h Ilum
1 gallon
3
10
Bleeding heart
Dicentra formosa
1 gallon
3
5
Lady fern
Athyrium filix-femina
4-inch pot
3
6
Total
41
Stream Buffer Enhancement South Side (approximately 369 square feet)
Salal
Gaultheria shallon
1 gallon
3
10
Red -flowering currant
Ribes sanguineum
1 gallon
3
10
Pacific rhododendron
Rhododendron
macro h Ilum
1 gallon
3
10
Bleeding heart
Dicentra formosa
1 gallon
3
5
Lady fern
Athyrium fifix-femina
4-inch pot
3
6
Total
41
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817 7th Ave N Stream Buffer Enhancement Plan
a ■ '
—369 square feet
Footbridge
14'
-385 square feet
T,. � R
a
N �� 0 Parcel27032400202200 Proposed Deck
CONFLUENCE — Shell Creek OHWM Area of deck within stream
ENVIRONMENTAL COMPANY
0 25 Drainage Feature buffer (-246 square feet)
Feet Proposed Enhancement
Meters Stream Buffer- 100 ft
0 5
Figure 5. Areas of Stream Enhancement.
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2.3 Maintenance
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Maintenance activities will include watering and weed control around plantings to ensure plant
establishment. The enhancement areas will be adaptively managed based on site conditions and
needs. The most crucial period to manage will be immediately after installation through the
second year as vegetation becomes established.
2.4 Performance Standards
The objective of the enhancement is to establish vegetation next to the stream to provide more
water quality protection, more wildlife habitat and fish habitat enhancement than the existing
buffer. Planted vegetation will be monitored for 3 years (Year 1, Year 3 and Year 5). Plant
survival and plant diversity will be monitored. The success criteria for the performance
standards are summarized in Table 3.
Table 3. Summary of Success Criteria
2.5 Monitoring
Plant survival will be documented within the enhancement area by comparing the number of
species of plants in the planting schedule to site conditions at the time of monitoring. The
percent survival is calculated by dividing the number of plants identified as alive during the
monitoring event by the number of plants identified on the planting schedule.
Monitoring will occur during the growing season after deciduous plants have flowered or
leafed out for easier identification.
Plant diversity will be determined by counting the number of species growing within the
enhancement area (planted and naturally recruited).
The applicant will provide documentation and photos to demonstrate compliance with
performance standards in Section 2.4.
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2.6 Contingency Plan
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Plant survival could be negatively affected by improper installation, diseased or infested plants,
inadequate watering, or extreme weather. If more than 25% of new plantings die in a single
year, the cause of the high losses will be investigated and corrected before dead plants are
replaced. Dead plant material will only be removed after that year's scheduled monitoring.
Plant diversity, as determined by the number of species within the enhancement area, could be
negatively affected by improper maintenance (e.g., watering or weeding) of the site. If the plant
diversity success criterion is not met, the cause will be investigated and corrected. Correction
measures may include a revision of planting palate and additional plantings.
3.0 FINANCIAL GUARANTEES
ECDC states that mitigation plans shall include financial guarantees, as necessary to ensure that
the mitigation plan is fully implemented. ECDC 23.40.290 states the bond shall be in the amount
of 120 percent of the estimated cost of the uncompleted actions or the estimated cost of restoring
the functions and values of the critical area that are at risk. The King County Critical Areas
Bond Worksheet was used to determine that the amount required for financial guarantee is
$2,077.This worksheet is attached in Appendix A.
4.0 REFERENCES
Confluence (Confluence Environmental Company). 2021. 817 Th Avenue North critical areas
study. Prepared for Max Gruici, Edmonds, Washington by Confluence Environmental
Company, Seattle, Washington.
Knight, K. 2009. Land use planning for salmon, steelhead, and trout. Washington Department of
Fish and Wildlife. Olympia, Washington.
July 9, 2021
Page 10
Appendix A
Financial Guarantee
Bond Worksheet
Stream Buffer Enhancement C24 09/09/2015
Bond Quantity Worksheet
Project Name: 817 7th Ave N Stream Enhancement Date: 7-Jul-21 Prepared by: Irene Sato
Project Description: Mitigate for single-family deck expantion into 246 square feet
Project Number:
of stream buffer.
Location: 817 7th Ave N, Edmonds WA 98020 Applicant: Max Gruici Phone:
PLANT MATERIALS (includes labor cost for
plant installation)
Type
I Unit Price
I Unit
Quantity
I Description
Cost
PLANTS: Potted, 4" diameter, medium
22.00
Native Herbacous Species:
$5.00
Each
bleeding heart, lady fern
$
110.00
PLANTS: Container, 1 gallon, medium soil
60.00
Native Shrub Species: Salal, red
flowering currant, pacific
$11.50
Each
rhododendron,
$
690.00
TOTAL
$
800.00
Percentage
ITEMS
of
Construction
Unit
Cost
Mobilization
10%
1
$
80.00
Contingency
30%
1
$
240.00
Page 1 of 2
TOTAL
$
320.00
NOTE: Projects with multiple permit requirements may be required to have longer
MAINTENANCE AND MONITORING monitoring and maintenance terms. This will be evaluated on a case -by -case basis
for development applications. Monitoring and maintance ranges may be assessed
anywhere from 5 to 10 years.
Maintenance, annual (by owner or consultant)
(3 X SF total for 3 annual events;
Less than 1,000 sq.ft. and buffer mitigation only
$ 1.08
SF
738.00
Includes monitoring)
$ 797.04
TOTAL
$ 797.04
Total
$1,917.04
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