21-104309-Wetland Mitigation Plan-10-14-2021-V1
WETLAND AND STREAM BUFFER
ENHANCEMENT PLAN
of the
Midway Samoan Assembly of God Property
29276 Military Rd. S.
Federal Way, WA 98003
Tax Parcel Number: 042104-9063, 042104-9032
Northeast Quarter of Section 04, Township 21, Range04E
Prepared for:
Pastor Matthew Taumua
29276 Military Rd. S.
Federal Way, WA 98003
Dated:
October 06, 2021
Prepared by:
Angelo Josue, PhD
Wetland Scientist
12909 66th Ave S., Seattle, WA 98178
website:www.arjwetlandservices.com
ARJ Environmental Consulting Services
Midway Samoan Church Property Mitigation Project October 2021
Table of Contents
Executive Summary ..................................................................................i
Chapter 1. Proposed Project ................................................................1
1.1 Introduction ...........................................................................1
1.2 Project Location ....................................................................1
1.3 Project Purpose ....................................................................1
1.4 Project Schedule ...................................................................2
1.5 Responsible Parties ..............................................................2
Chapter 2. Existing Conditions ............................................................2
2.1 Landscape Setting ...........................................................2
2.1.1 Wetland ...................................................................2
2.1.2 Stream ….................................................................3
2.1.3 Upland/Buffers ........................................................3
2.2 Current Land Use...................................................................3
Chapter 3. Wetland and Buffer Impact Assessment ………………….3
3.1 Existing Conditions of Wetland and Buffers
to be Impacted …………………………………………………..3
3.2 Wetland Impacts ………………………………………………..4
3.2.1 Permanent Wetland Impacts ………………………...4
3.2.2 Temporary Wetland Impacts………………….………4
3.3 Wetland Buffer Impacts………………………………….……..4
3.3.1 Permanent Buffer Impact……………………….……..4
3.3.2 Temporary Buffer Impact………………………….…..5
3.4 Wetland Functions Impacted……………………………….….5
3.5 Wetland Impact Summary Sheet……………………………...5
Chapter 4. Stream and Stream Buffer Impact Assessment…………....5
4.1 Existing Conditions of Stream to be Impacted………………..5
4.2 Stream Impacts…………………………………………………...6
4.2.1 Permanent Stream Impacts…………………………….6
4.2.2 Temporary Stream Impacts…………………………….6
4.3 Stream Buffer Impacts ……………………………….………..6
4.3.1 Permanent Stream Buffer Impacts……………………..6
4.3.2 Temporary Buffer Impacts……………………………...6
4.4 Stream Habitat Impacted ……………………………………….6
Midway Samoan Church Property Mitigation Project October 2021
Chapter 5. Mitigation Strategy…………………………….………………..6
5.1 Avoidance and Minimization of Wetlan d
and Stream Impacts………………………………………………7
5.2 Compensatory Mitigation………………………………………...7
5.2.1 Regulatory Requirements………………………………..7
5.2.2 Project Mitigation Proposal ……………………………..8
5.2.3 Temporary Wetland and Buffer
Impact Restoration……………………………………….8
Chapter 6. Compensatory Mitigation for Wetland, Stream, and
Buffers……………………………………………………………..9
6.1 Site Location……………………………………………………….9
6.1.1 Landscape Position……………………………………….9
6.1.2 Ecological Connectivity…………………………………. 9
6.1.3 Historic and Current Land Use …………………………9
6.2 Rationale for Site Selection……………………….………………9.
6.3 Existing Condition of Compensation Site………………………10
6.3.1 Wetland……………………………………………………..10
6.3.2 Stream………………………………………………………10
6.3.3 Uplands…………………………………………………… 10
6.3.4 Wildlife and Habitat Use………………….…….. ……… 10
6.4 Compensation Design ……………………………. …. …………10.
6.4.1 Site Hydrology…..…………………………………………10
6.4.2 Site Preparation ……..……………..……………………..11
6.4.3 Plant and Planting Preparations…………………………11.
6.4.4 Installation of Plants……………………………………… 11
6.4.5 Soil Management for Sewer
Trench Excavation…………………………………………11.
6.5 Wetland and Stream Benefits …………………………………..12
6.5.1 Wetland Functions……………………………………….. 12
6.5.2 Buffer Function…………………………………………… 12
Chapter 7. Mitigation Goals, Objectives, and Performance Criteria …12
7.1 Wetland Mitigation Goals, Objectives,
and Performance Criteria ……..…………………………………12
7.1.1 Goal ……………………………………………………… …12
7.1.2 Objectives ………………………………………… ………..12.
7.1.3 Performance Criteria ………………………………………12
7.2 Wetland Buffer Mitigation Goals, Objectives, and Performance
Criteria ……………………………………………………………… 13
7.2.1 Goals .……………………………………………………….. 13
7.2.2 Objectives .……………………………………………………13
7.2.3 Performance Criteria. ………………………………………13
Midway Samoan Church Property Mitigation Project October 2021
7.3 Buffer Mitigation Goals, Objectives and Performance
Criteria……………………………………………………………13
7.3.1 Goals…………………………………………………………13
7.3.2 Objectives…………………………………………………….13
7.3.3 Performance Criteria………………………………………..13
Chapter 8. Management Program……………………………………………..14
8.1 Maintenance Plan ….………………………………………………...14
8.2 Monitoring Plan …..…………………………………………………15
8.3 Contingency Plan …. ……………………………………………….15
8.4 Performance Bond …..……………………………………………. 15
8.4.1 Bond Quantity Worksheet (see attached ) ………………. 15
Chapter 9. Limitations ……………………………………………………………15
Chapter 10. Signature of Preparer ……………………………………………..16
Chapter 11. References …………………………………………………………..17
Table and Figures
Table 1 – Summary of Project Wetland, Stream, and Buffer Impacts and
Compensatory Mitigation ……………………………………………ii
Table 2 - Function/Value of the Category III, Depressional Wetland …… ..18
Table 3 - Summary of Wetland and Buffer Impact …………………………..19
Table 4 - Summary of Stream and Buffer Impact …………………………….20
Figure 1 - Aerial View of Project Site ……………………………………………21
Figure 2 – Portion of Category III Wetland …………………………………… .22
Figure 3a & b - Stream Condition ………………………………………………..23
Figure 4 - Panoramic View of the Parcels with the Existing Structures. ……..23
Attachments
Bond Quantity Worksheet Planting Design Sketch Plan
i Samoan Assembly of God Property Mitigation Plan October 2021
Executive Summary
The applicant is submitting the proposed wetland and stream buffer
enhancement plan for the purpose of mitigating the impacts to its category III wetland
and Type F stream and as a requirement for a 25 % buffer reduction application.
The mitigation project is located at 29276 Military Rd. S., Federal Way, WA
98003. The site can be further described as located in the northeast quarter of
Section 04, Township 21, Range 04 East of the Willamette Meridian in the
drainage basin of Green River in the Duwamish-Green River Watershed and
WRIA-9 (Duwamish-Green 9).
The proposed project have unavoidable wetland impact. Impact to the wetland
covers approximately 345 sq. ft. and about 913 sq. ft. of wetland buffer, both within the
ROW dedication area. Additional impact to the wetland buffer due to the 25% buffer
reduction is about 7,778 sq. ft. The temporary impacts to the wetland, stream, and
buffers is approximately 5,921 sq. ft. are due to the deconstruction of the work shed
and the excavation for the sewer line.
Most of the temporary impacts occur along the buffers which have low level of
vegetation that is almost a monoculture of reed canary grass. A large portion of the
buffer are bare ground consisting of sand and gravel and occasional clumps of weeds.
The mitigation strategy described in this proposal include avoidance,
minimization of wetland, stream, and buffer impacts including compliance to local
regulations designed to protect critical areas. The mitigation will compensate
permanent and temporary impact to the Category III wetland and Type F stream and its
buffers, by vegetation enhancement and rehabilitation of disturbed areas. A total of
16,028 sq. ft. of the wetland and buffer will be mitigated to compensate for the impacts.
The overarching goal is to enhance the wetland by establishing native plant
species in the wetland and buffer. The enhanced vegetation will improve its buffering
potential; improve its habitat functions; improve species richness and vegetative
structure; increase its educational value, all of which are presently low or absent in the
subject location..
The mitigation plan also describes an adaptive management program that include
maintenance, monitoring/reporting and contingency plan and tak ing appropriate actions
to correct any deficiencies that may occur during the project life of 5 years.
ii Midway Samoan Church Mitigation Project October 2021
Table 1. Summary of Project Wetland, Stream, Buffer Impacts and Compensatory Mitigation.
Region LRRA Region
Contract Name and Number Midway Samoan Assembly of God Church
Township/Range/Section Northeast Quarter of Section 04, Township 21, Range 04E
Jurisdictional Wetland
Impact Areas
0 0
Regulated by USACE
and Ecology Regulated by Ecology (Isolated)
Mitigation Location
29276 Military Rd. S.
Federal Way , WA 980003
Wetland Category/Buffer Category III/80 ft
Stream Type/Buffer Type F/100 ft
Permanent Wetland Impact 534 sq ft
Temporary Wetland Impact 10 sq ft
Permanent Buffer Impact 8,691 sq ft
Temporary Buffer Impact 1,300 sq ft
Permanent Stream Impact None
Temporary Stream Impact 200 sq ft
Permanent Buffer Stream
Impact None
Temporary Stream Buffer
Impact 586 sq ft
Area & Type of Mitigation 1,416 sq ft / wetland vegetation enhancement
Area & Type of Mitigation 8,691 sq ft/wetland buffer enhancement
Area & Type of Mitigation 5,921 sq ft/ wetland buffer rehabilitation
Total Area of Mitigation 16,028 Sq ft
Years of Monitoring 5 years
1 Midway Samoan Church Mitigation Project October 2021
WETLAND AND STREAM BUFFER
ENHANCEMENT PLAN
Chapter 1.0 - Proposed Project
The applicant is submitting the proposed wetland and stream buffer
enhancement plan for the purpose of mitigating the impacts to its category III
wetland and Type F stream buffers and as a requirement for a 25 % buffer
reduction application. The mitigation plan will compensate for the permanent
and temporary impacts as a result of the proposed development plan in the
subject parcel.
This document describes the impacts to the critical areas, mitigation strategy,
goals and performance standards, management plan that includes plant
establishment, maintenance, monitoring, and contingency plan.
1.1 Introduction
The document describes the conceptual framework to compensate
for impacts due to site development, for wetland, stream, and buffers . The
enhancement plan will mitigate for the permanent and temporary impacts
as a result of the proposed development.
1.2 Project Location
The property is located at 29276 Military Rd. S., Federal Way, WA
98003 (See Figure 1). The site can be further described as
located in the northeast quarter of Section 04, Township 21,
Range 04 East of the Willamette Meridian .The site is located in
the drainage basin of Green River in the Duwamish-Green River
Watershed and WRIA-9 (Duwamish-Green 9).
1.3 Project Purpose
The purpose of this proposal is to develop a mitigation plan to compensate
for the unavoidable and temporary impacts as a result to the proposed
development of the parcels and to compensate for a 25% buffer reduction.
2 Midway Samoan Church Mitigation Project October 2021
1.4 Project Schedule
The mitigation measures can be installed in at least 2 to 3 weeks.
Establishment of native plants is recommended at the start of Spring or
Fall.
1.5 Responsible Parties
The entire project development will be administered by Magellan
Architects including its Partners. Maintenance and monitoring of the
mitigation project will be done by the preferred consultant to be hired
by the Midway Samoan Assembly of God management. Long-term
stewardship of the property will be the responsibility of the property
owners.
2.0 Existing Conditions
There are two parcels on the project site. The parcel 042104-9063 is
approximately 86,684 sq. ft. parcel 042104-9032 is approximately 21,344 sq..
ft. Both parcels have building structures at the southwest corners of the
property. More half of the entire parcel are covered with sand and gravel and
utilized as parking areas.
The parcels are bound by Military Road S. to the west and single-family homes
to the east, south, and north. The northeast of the larger parcel is populated
with trees, shrubs, and herbaceous plant species. The parcel has a vegetated
area to the northeast corner populated with deciduous trees, Himalayan
blackberry, willows, reed canary grass, creeping buttercup, mix grass species,
and Himalayan blackberry.
2.1 Landscape Setting
2.1.1 Wetlands
There is a wetland on the subject property toward the north and east
portions of the parcel. The wetland is part of a larger wetland that extend s
to the adjacent parcels to the north. The wetland has a palustrine scrub-
shrub(PSS) and palustrine emergent (PEM) classes of vegetation
(Cowardin, 1979). The hydrophytic plant community is dominated by
Pacific willow, reed canary grass, creeping buttercup, Himalayan
blackberry. The hydrogeomorphic classification is a Depressional
wetland. Its sources of hydrology are seepage, precipitation, storm water
3 Midway Samoan Church Mitigation Project October 2021
discharge, and surface runoff. The soils are a hydric clayey muck with
one-chroma matrix with water table at 17 to 23 (Figure 2).
2.1.2 Streams
An off-site stream that abuts the parcels to the east is mapped in the King
County iMap as a Type F stream. The permanently disturbed stream has
no running water and is dry during the summer season up until the start of
the rainy months starting during the fall season. Water is accumulated in
the stream channel from surface runoff, precipitation, and snowmelts.
There is no fish or aquatic habitat. The streambed and adjacent berm to
the west is covered with grasses and is regularly mowed (Figure 3a, 3b).
2.1.3 Buffers/Uplands
The wetland buffer in the upland portions of the parcel are permanently
altered from previous development. It is previously filled with sand and
gravel with grasses, plantain, creeping buttercup, and other weeds.
Portions of the wetland buffer are used as parking spaces and a remnant
of a deconstructed building lies in the middle of the buffer area. Stream
buffer that extends to the parcel west of the stream overlaps with the
wetland buffer. There is no stream buffer to the east of the stream, it is
lined with residential houses that was previously its top-of-bank. (Figure
4).
2.2 Current Land Use
The larger parcel has a church building toward the southwest portion. The
surrounding area around it are utilized as parking areas for churchgoers and
visitors. The smaller parcel to the south has an abandoned cottage at the
southwest corner. Similarly, the immediate surroundings are vacant spaces,
bare ground with sand and gravel that is utilized as parking spaces.
3.0 Wetland and Wetland Buffer Impact Assessment
3.1 Existing Conditions of Wetland and Buffers to be Impacted
The wetland area that will be impacted is at the northwest corner of the
parcel. It is heavily infested with Himalayan blackberry and rubbish are
also present in some portions. A concrete storm drain that has a large
crack drains storm water into the wetland during rain and snowmelt
events. Wetland buffers that will be impacted are areas of the buffer that
4 Midway Samoan Church Mitigation Project October 2021
are permanently disturbed from previous development activity. Portions
have sand and gravel around building structures, a concrete footing from
a previously deconstructed building, and buffer area that is regularly
mowed. Wetland and buffer impacts are summarized in Table 3.
3.2 Wetland Impacts
The unavoidable impacts to the Category III wetland is portion of the right-of-
way dedication area along the west property lines of the parcels that abuts
Military Road S. There is no filling up or removal of wetland in this location.
The location is currently portion of undeveloped sidewalk.
3.2.1 Permanent Wetland Impacts
A total of approximately 354 sq. ft. of the ROW dedication area is within the
designated wetland area towards the northwest corner of the parcel. About
213 sq. ft. will be impervious surface in this location. Approximately 913 sq.
ft. of wetland buffer is within the ROW dedication area and will have an
impervious area of 213 sq. ft.
3.2.2 Temporary Wetland Impacts
Temporary wetland impacts will result from the demolition of the shed in
the north portion of the parcel which is along the wetland and from the
sewer line installation toward the southeast portion of the parcel (see
Option A). Shed demolition will approximately disturbed 10 sq. ft. of
wetland. There are no reduction or loss of wetland functions due to
this activity. About 63.10 ft. of sewer line will be installed along the
wetland area, with an estimated work area of 638 sq. ft.
3.3 Wetland Buffer Impacts
Impacts to the wetland buffer are due to the ROW dedication and
installation of sewer lines and the proposed 25 % wetland buffer reduction.
3.3.1 Permanent Wetland Buffer Impacts
A total of 913 sq. ft. of the ROW dedication area is within the proposed buffer
area with about 547 sq. ft. as impervious surface. The 25% buffer reduction is
approximately 7,778 sq. ft. of the entire wetland buffer.
5 Midway Samoan Church Mitigation Project October 2021
3.3.2 Temporary Wetland Buffer Impacts
Temporary impacts to the wetland buffer include the split-rail fence line to
be installed along the edge of the wetland buffer that is approximately 558 ft .
in length. The proposed fence line is in areas that are bare ground with
sand and gravel with occasional weeds along it. The sewer line installation
will run about 179.5 ft. along wetland buffer. Portions of the buffer are
vegetated with grasses.
3.4 Wetland Functions Impacted
The Category III, Depressional, Closed system wetland provides functions for
flood flow alteration, sediment removal, moderate nutrient and toxicant
removal, production of organic matter, moderate habitat suitability, and
educational values.
Impacts to the overall functions of the wetland are not expected in the project
area. The buffering function that has been permanently disturbed is the major
wetland function that is impacted and will be the focus of this mitigation plan.
There are no impacts to the hydrologic, water quality or biological functions of
the overall Category III wetland. Table 2 summarizes the functions of the
Category III Depressional wetland.
4.0 Stream and Stream Buffer Impact Assessment
The off-site stream is classified in the DENR FPARS and King County GIS maps
as a Type ‘F” waters Federal Way City Code 19.145.260.2.b. It is identified as
Bingaman Creek which originates from Bingaman Pond approximately 1.03 miles
to the northeast. According to the Federal Way Municipal Code Chapter
19.145.270.1.a - Stream Buffers Type F stream shall have a buffer width of 100
ft. measured from the Ordinary High Water Mark (OHWM) (see wetland report).
The mapped stream does not contain aquatic habitat and there are no fish
reported in this creek. It is dry during the spring to late fall when the rainy season
starts. Water accumulates in the streambed due to precipitation and runoff from
adjacent impervious surfaces from the east that are mainly residential homes
Stream and buffer impacts are summarized in Table 4.
4.1 Existing Conditions of Stream to be Impacted
The Type F stream is permanently degraded and covered with grasses that is
regularly mowed. There is no water or aquatic habitat structures along
both sides of its banks. There are no fish present. The stream bank to the
6 Midway Samoan Church Mitigation Project October 2021
east are lined with residential homes while the west side is a raised flat berm
about 12 to15 feet in width populated with a mixture of lawn grasses that is
regularly mowed.
4.2 Stream Impacts
4.2.1 Permanent Stream Impacts
There are no permanent impact to the stream.
4.2.2 Temporary Stream Impacts
The temporary impact to the stream is due to the excavation to install the
sewer line going to the residential areas in the east. Approximately 894 cu.
ft. of soil will be excavated for the trench 6 ft. wide and 20 ft. long, with an
average depth of 7.45 ft. across the stream. The excavated soil will be set
aside and the same will be used to fill it back to grade.
4.3 Stream Buffer Impacts
The 100 ft. Type F stream buffer overlaps with the wetland buffer on the
southeast corner of the parcels.
4.3.1 Permanent Stream Buffer Impacts
There is no permanent impact to the stream buffer.
4.3.2 Temporary Buffer Impacts
The temporary impact is due to the excavation for the sewer line.
Approximately 2,328 cu. Ft. of soil will be excavated in a trench 6 ft. wide
and 111 ft. long. Excavated soil will be carefully piled along the side of
the trench and will be put back after the sewer lines are installed.
4.4 Stream Habitat Impacted
There are no stream habitat impacted.
5.0 Mitigation Strategy
The mitigation strategy described in this proposal includes avoidance
minimization of wetland, stream, and buffer impacts for permanent and
temporary impacts. The mitigation will also employ repairing and restoring
disturbed areas including monitoring of impacted areas and taking appropriate
7 Midway Samoan Church Mitigation Project October 2021
actions to correct any deficiencies that may occur. In addition, the plan involves
the implementation of an adaptive management plan over a period of 5 years to
insure that performance measures are attained and impacts are eliminated.
5.1 Avoidance and Minimization of Wetland and Stream Impacts
The proposed development project avoids and minimizes potential impacts to
critical areas to the extent that is possible and practicable. Total avoidance is not
possible because of associated design guidelines and safety considerations.
Mitigation will compensate for impacts through enhancement of wetland and its
buffer and rehabilitation of temporary disturbance in said areas.
5.2 Compensatory Mitigation
5.2.1 Regulatory Requirements
There is no direct, permanent development activity within the wetland, nor
activities that will directly impact the drainage or storm water system in th e
project vicinity. The proposed project will not result to the reduction of
wetland area. The ROW dedication area that encroaches part of the
Category III wetland including temporary disturbance will be mitigated by
rehabilitating wetland vegetation.
The proposal complies with the provisions of the Federal Way Revised Code
(FWRC) 19.145.440.6, with the following criteria:
(a) It will not adversely affect water quality;
(b) It will not adversely affect the existing quality of the wetland or
buffer wildlife habitat;
(c) It will not adversely affect drainage or storm water retention
capabilities;
(d) It will not lead to unstable earth conditions nor create erosion
hazards;
(e) It will not be materially detrimental to any other property or the
city as a whole; and
(f) All exposed areas are stabilized with native vegetation, as
appropriate.
The ratio of 4:1 per Federal Way Revised Code FWRC 19.145.430
(Development Within Wetlands) will be used to compensate for wetland
disturbance through enhancement and rehabilitation.
Temporary impacts to buffer areas will be mitigated by vegetation
enhancement using a mitigation ratio of 1:1. There are no adverse
8 Midway Samoan Church Mitigation Project October 2021
impacts to water quality, hydrology, or wildlife habitat. The parcel is not
mapped as an aquifer recharge site, the stream is permanently degraded
and there is no flowing water nor is there aquatic habitat for wildlife usage.
Construction activities will be done during dry months of the year and will
employ best management practices to control pollution and erosion.
5.2.2 Project Mitigation Proposal
The proposed project will permanently impact 354 sq. ft. of Category III,
Depressional wetland. This impact is part of the ROW dedication area
along the west side of the property along Military Road S. It will not affect
flood flow alteration, sediment removal, nutrient/toxicant removal, organic
matter production and export, general habitat functions or native plant
richness.
To comply with regulations the impacted wetland will be enhanced with
native plant species as recommended in FWRC 19.145.440 with an
enhancement ratio of 4:1 for Category III wetlands. The wetland
vegetation enhancement will be approximately 1,416 sq ft (see Planting
Design Sheet 1 and 2).
Likewise, the wetland buffer will have permanent impacts due to ROW
dedication area and to the 25% buffer reduction. The areas are
approximately 913 sq. ft. and 7,778 sq. ft., respectively. The buffer impacts
will be compensated by native plant enhancement within the remainder of
the wetland buffer. The mitigation ratio to be used is 1:1 or a total of 8,691
sq. ft. (see Planting Design Sheet 1 and 2).
5.2.3 Temporary Wetland and Buffer Impact Rehabilitation
Temporary impacts to the wetland is due to the demolition of the existing
shed to which about 10 sq. ft. is within the wetland and about 662 sq. ft.
with its buffer. Additionally, wetland and stream buffers will have
temporary disturbance as a result of the sewer line excavation, existing
septic demolition,fence installation, and trash corral area. The total area
of temporary impact is about 5,921 sq. ft.
Areas with temporary impacts will be rehabilitating an equal amount of
impacted area, by replacing back the soil that was excavated and
establishing the existing vegetation that was disturbed. Table 3 shows the
summary of wetland, stream and buffer impacts.
9 Midway Samoan Church Mitigation Project October 2021
6.0 Compensatory Mitigation for Wetland, Stream, and
Buffers
6.1 Site Location
The mitigation will be done on-site particularly along the north property line of
the parcel where the wetland edge is located. The site is in the NE quarter of
Section 04, Township 21, Range 04E. Portions of the site has been utilized
as a work shed and wetland is covered by Himalayan black berry and trash.
6.1.1 Landscape Position
:
The site is located in an urban landscape that are predominantly residential
and commercial establishment. The topography is slightly undulating with
the wetland in a basin-like topography. The wetland has no connections
with other water bodies. A stream identified as Bingaman Creek is mapped
along the east side of the wetland. The stream originates from Bingaman
Pond farther to the north. The stream is however, permanently degraded
and obscured by previous development.
6.1.2 Ecological Connectivity
The mitigation site is the southern most portion of the larger part of the
wetland that extends to the north. It is not connected to the off-site stream
to the east.
6.2.3 Historic and Current Land Use
The site is within the urban zone consisting of single-family residence and
townhomes/apartments in the project vicinity. The site is under the
jurisdiction of Federal Way in unincorporated status within the Commun ity
Planning Area of Federal Way.
6.2 Rationale for Site Selection
Under present conditions of degraded on-site wetland and its buffers, the
on-site mitigation is considered important in improving the overall quality
of the impaired wetland functions in terms of its water quality, native plant
diversity, and educational value.
10 Midway Samoan Church Mitigation Project October 2021
6.3 Existing Condition of Compensation Site
6.3.1 Wetland
The Category III, palustrine scrub-shrub (PSS), Depressional wetland in
the mitigation site is degraded due to invasive Himalayan black berry and
presence of trash materials accumulated over time. The overall
vegetation along this side of the wetland is covered with Himalayan
blackberry. Wetland hydrology is largely dependent on storm water
runoff, precipitation and snowmelt. The soil along the northwest portion of
the proposed mitigation site is gravelly sandy loam and loamy muck soil.
The buffer condition along this portion is permanently altered and its
buffering function is degraded.
6.3.2 Stream
The stream classified as a Type F stream is permanently degraded. As
earlier stated, it has no water flow and no aquatic habitat to support fish or
other aquatic species. Water is present only as a result of surface runoff
from adjacent impervious surfaces from homes and streets, or from rainfall
and snowmelt. The stream bank and berm is covered with lawn grass and
is mowed regularly.
.
6.3.3 Uplands
Portion of the upland areas in the parcel are part of the wetland buffer. This
will be utilized for the buffer enhancement to compensate for the temporary
and permanent impacts on the buffers. The soil type is largely gravelly
sandy loam, portions of which are previously filled materials of sand and
gravel. Most of the existing wetland buffer is bare ground with occasional
grasses and weeds in some places.
6.3.4 Wildlife and Habitat Use
There are no habitat structures in the wetland buffer occasionally, flocks of
geese forage in the grassy area in the wetland buffer.
6.4 Compensation Design
6.4.1 Site Hydrology
The site relies on rainfall for its source of hydrology. The presence of water
is seasonal and the wetland dries up. Provision for maintenance of installed
plants will be done to insure sufficient amount of water is available for
normal growth especially during the dry months of the year.
11 Midway Samoan Church Mitigation Project October 2021
6.4.2 Site Preparation
Prior to the establishment of native plants, areas of the wetland and in
buffer areas will be prepared by manually removing invasive plants and
trash. Plants and materials removed from the site shall be disposed
properly off-site. Care should be taken to preserve any other vegetation
growing in the wetland buffer.
No heavy equipment will be used to install the plants. Care should be
done to minimize destructive impacts on the wetland and stream buffer
6.4.3 Plant and Planting Preparations
Native plant species is listed in the plant schedule. These can be sourced
from commercial nurseries growing wetland species or bought as potted
plants, seeds, or other vegetatively propagated plants.
(see plant design).
6.4.4 Installation of Plants
Planting procedure for native plant species is shown in the planting detail.
Soil amendment using compost will be used for each hill of plant to be
established. Mulch should cover the immediate surrounding of the
established plants. Grass seeded areas should be covered with hay/straw
to minimize erosion, protect the seeded materials from heavy downpour or
disturbance from foraging birds.
6.4.5 Soil Management for Sewer Trench Excavation
The excavation of trench for the sewer line shall follow Option 4 of the King
County Soil Management Plan. The soil excavated from each of the
section such as wetland and stream buffer, wetland, and stream will be
stockpiled onsite and kept separately along side the buffer section of the
trench. After excavation the soil should be covered with appropriate tarp
material to prevent excessive drying. After installing the sewer lines, the
disturbed sites will be rehabilitated by re-applying the stock piled soil from
each section and the surface amended with organic compost about 3
inches thick prior to seeding with grass seeds. Grass seeding will be
covered with hay to prevent erosion and to protect seeds from foraging
birds.
12 Midway Samoan Church Mitigation Project October 2021
6.5 Wetland and Stream Benefits
6.5.1 Wetland Functions
The mitigation plan in the on-site Category III wetland will contribute
to improve the water quality, hydrologic, and habitat of the overall
functions of the entire wetland in contrast to its current conditions.
6.5.2 Buffer Function
The enhanced buffers will provide improved buffering to protect the onsite
wetland with the introduction of native plant species and the installation
of split-rail fence that will separate the rest of the critical areas from the
developed areas of the parcel.
7.0 Mitigation Goals, Objectives, and Performance
Criteria
7.1 Wetland Mitigation Goals, Objectives, and Performance Criteria
7.1.1 Goal
Enhance 1,416 sq. ft. of Wetland with Native Vegetation.
7.1.2 Objectives
Install native species of shrubs and herbaceous native plant
species
7.1.3 Performance Criteria
After installation of the native plant species the area will
measure approximately 1,416 sq. ft.
Trees and shrub cover will be >10% after Year 1; >20% after
Year 2; > 35% after Years 3 to 5.
Invasive species will not make up 10% cover in any growing
season.
13 Midway Samoan Church Mitigation Project October 2021
7.2 Wetland Buffer Mitigation Goals, Objectives, and Performance Criteria
7.2.1 Goals
Enhance 8,691 sq. ft. of Wetland Buffer
7.2.2 Objectives
Install native species of shrubs and herbaceous native plant
species to compensate for permanent wetland buffer impacts
due to (ROW dedication (913 sq. ft.) and the 25% buffer
reduction of 7,778 sq. ft.).
7.2.3 Performance Criteria
After installation of the native plant species the area will
measure approximately 8,691 sq. ft.
Trees and shrub cover will be >10% after Year 1; >20% after
Year 2; > 35% after Years 3 to 5.
Invasive species will not make up 10% cover in any growing
season.
7.3 Buffer Mitigation Goals, Objectives and Performance Criteria
7.3.1 Goals
Rehabilitate approximately 3,835 sq. ft. of temporary
disturbance.
7.3.2 Objectives
Replant approximately 3,835 sq. ft. of wetland and stream
buffer as a result of a temporary disturbance due to sewer
installation.
7.3.3 Performance Criteria
After rehabilitation the area will measure approximately 3,835
sq. ft.
Herbaceous groundcover cover will be >10% after Year 1;
>20% after Year 2; > 35% after Years 3 to 5.
Invasive species will not make up 10% cover in any growing
season.
14 Midway Samoan Church Mitigation Project October 2021
8.0 Management Program
8.1 Maintenance Plan
In order to achieve performance standards, the applicant shall have the wetland
buffer area maintained for the duration of the monitoring period. Maintenance
activities will be done at least two or more operations per year (April and
September). Maintenance will include watering, weeding around base of
installed plants, replacement, re-staking, and removal of all classes of noxious
weeds. The applicant shall replace any plants that are failing, weak, defective
in growth, or dead during the growing season. Replacement plants shall meet
the same standards for size and type as those specified for original installation
unless otherwise specified by the consulting biologist. Chemical controls shall
not be used unless written permission is obtained from Federal Way Permitting
Division. All invasive material and debris is to be disposed of lawfully off -site.
8.2 Monitoring Plan
The applicant’s environmental consultant will perform a three -year monitoring
program. A monitoring report will be submitted to the Federal Way Permitting
Division by December 31st of each year beginning the first fall after
enhancement installation. Annual monitoring activities will be implemented to
evaluate the progress of the project and to determine if the stated objectives
are being met. The data obtained from the “As Built” condition right after the
installation of the all components of the enhancement project will be the
baseline information for the annual monitoring.
Performance measures enumerated for the wetland and wetland buffer will be
collected and recorded. Sample points or transects will be established for
vegetation monitoring. Photo-points will be established from which photos will
be taken throughout the monitoring period. Permanent transect location(s)
will be identified on the approved enhancement plans in the first monitoring
report. Plots located at the end of each transect shall detail herb and shrub
aerial cover at radii of 1m, 5m, and 10m respectively, using the Braun -
Blanquet Releve method or other acceptable field method. Monitoring of
vegetation transects shall occur annually between April and September 30,
prior to leaf drop, unless otherwise specified.
A monitoring report will be prepared stating among others if the objectives of
the enhancement project are being met, problems encountered, and adaptive
management recommended to correct the problems. The report may include
the following information among others:
15 Midway Samoan Church Mitigation Project October 2021
Project reference number
Site plan and location map
Historic description of the project, including date of installation, current
year of monitoring, restatement of enhancement goals, and performance
standards
Plant survival, vigor, and aerial coverage from every plant community and
an explanation of monitoring methodology in the context of assessing
performance standards
Buffer conditions, e.g. surrounding land use, use by humans, presence or
absence of wildlife.
Observed wildlife, including amphibians, avians and others.
Assessment of nuisance/exotic biota and recommendations for
management
Photographs taken from permanent photo-points as shown on
enhancement plan
Summary of maintenance and contingency measu res proposed for next
season and completed last season.
8.3 Contingency Plan
If the annual monitoring report reveal the enhancement has failed in whole
or in part, and should that failure be beyond the scope of routine
maintenance, a contingency plan will be submitted. Once approved, it
may be installed, and will replace the approved enhancement plan. If
failure is substantial, the Federal Way Permitting Division may extend the
monitoring period for the enhancement of the wetland and wetland buffer.
8.4 Performance Bond
At the time of permitting, the applicant must provide an enhancement
bond or assignment of funds per Federal Way Revised Code. The
following is a Bond Quantity Worksheet for construction, installation,
maintenance and monitoring of the proposed mitigation (see attached).
9.0 Limitations
Wetland and wetland buffer enhancement plans are not final until
approved by regulatory agencies and/or local jurisdictions. ARJ
Environmental Consulting Services does not guarantee acceptance or
approval by regulatory agencies, or that any intended use will be
achieved.
16 Midway Samoan Church Mitigation Project October 2021
10.0 Signature of Preparer:
_________________________
Angelo Josue, PhD
Principal
ARJ Wetland Environmental Consulting Services
12909 66th Ave. S.
Seattle, WA 98178
17 Midway Samoan Church Mitigation Project October 2021
11.0 References
Cowardin, Lewis M. 1979. Classification of Wetlands and Deepwater
Habitats of the United States. U.S. Fish and Wildlife Service. Jamestown,
North Dakota.
Environmental Laboratory. 1987. Corps of Engineers Wetlands Delineation
Manual. Technical Report Y-87-1.US Army Corps of Engineers Waterways
Experiment Station, Vicksberg, MS.
Hruby, T. (2014). Washington State Wetland Rating System for Western
Washington: 2014 Update. (Publication #14-06-029). Olympia, WA:
Washington Department of Ecology.
Federal Way Revised Code. Current through Ordinance 21-920, passed
August 10, 2021.https://www.codepublishing.com/WA/FederalWay.
King County Department of Permitting and Environmental Review. 2012.
Critical Areas Mitigation Guidelines. 19Pp. www.metrokc.gov.
Lichvar, R.W., D.L. Banks, W.N. Kirchner, and N.C. Melvin. 2016. The
National Wetland Plant List: 2016 Wetland Ratings. Phytoneuron 2016-30:
1-17. Published 28 April 2016.ISSN 2153 733X.
US Army Corps of Engineers. May 2010. Regional Supplement to the Corps
of Engineers Wetland Delineation Manual: Western Mountains, Valleys, and
Coast Region Version 2.0.
Washington State Department of Ecology.U.S.Army Corps of Engineers
Seattle district and U.S. Environmental Protection Agency Region 10.
2006b. Wetland Mitigation in Washington State - Part 2: Developing
Mitigation Plans (Version 1).
Washington State Department of Ecology, U.S. Army Corps of Engineers
Seattle District, and U.S. Environmental Protection Agency Region 10.
2006a. Wetland Mitigation in Washington State – Part 1: Agency Policies
and Guidance (Version 1). Washington State Department of Ecology
Publication #06-06-011a. Olympia, WA. [March 2006]
http://www.ecy.wa.gov/pubs/0606011a.pdf
Washington State Department of Ecology, U.S. Army Corps of Engineers
Seattle District, and U.S. Environmental Protection Agency Region 10.
2006b. Wetland Mitigation in Washington State – Part 2: Developing
Mitigation Plans (Version 1). Washington State Department of Ecology
Publication #06-06-011b. Olympia, WA. [March 2006]
http://www.ecy.wa.gov/pubs/0606011b.pdf
18 Midway Samoan Church Mitigation Project October 2021
Table 2. Function/Value of the Category III, Depressional Wetland.
Function/Value Wetland
Present Description
Flood Flow Alteration + Receives storm water from city
drainage;
Runoff from adjacent
impervious surface.
Sediment Removal + Contaminated water drains into
the wetland.
Nutrient and Toxicant Removal + Dense groundcover of grasses
helps in removing
nutrients/toxicants
Erosion Control & Shoreline Stabilization np Wetland not part of a stream
channel down gradient
Production & Export of Organic Matter x Production of OM present,
export of OM is absent with no
defined outlet.
General Habitat Suitability x Plant communities low, open
water not present
Habitat for Aquatic Invertebrates np No aquatic habitat structures
Habitat for Amphibians np No aquatic habitat structures
Habitat for Wetland-Associated Mammals x No permanent inundation
Habitat for Wetland-Associated Birds x No open water or emergent
vegetation
General Fish Habitat np Stream permanently degraded
Native Plant Richness x Low species diversity, mostly
invasive species as cover the
wetland
Educational or Scientific Value x No educational program or
research on-site
Uniqueness and Heritage x Wetland not listed
a “np” means that the function is not present; “X” means that the function is present and is of low
quality; and “+" means the function is present and is of high quality.
19 Midway Samoan Church Mitigation Project October 2021
Table 3. Summary of Wetland and Buffer Impact.
Wetland Impacts Summary Sheet
Local Jurisdiction City of Federal Way
WRIA 9 (Duwamish-Green
River).
Ecology Rating
(Hruby 2004) Category III
Local Jurisdiction
Rating Category III
Local Jurisdiction
Buffer Width 80 ft
Wetland Size 0.94 acres
Cowardin
Classification Palustrine Scrub-Shrub
HGM Classification Depressional
Wetland Rating System Pts.
Water Quality Score
Hydrologic Score
Habitat Score
Total Score
7
8
4
19
Wetland and Buffer Impact Summary
Wetland Impacts
Permanent
Temporary
Indirect
354 sq ft (0.86% of On-Site Wetland)
1,300 sq ft
0
Buffer Impacts Permanent
Temporary
913 sq ft + 7,778 sq ft = 8,691 sq ft
3,835 sq ft
Dominant
Vegetation Impacted Himalayan black berry, grass weeds
Soils Series
Impacted Gravelly sandy loam, loamy muck soil
Hydrology Impacted None
Wetland Functions Impact Summary
Water Quality
The impacted portion of the Category III wetland is part of the ROW dedication area,
where the wetland edge starts with a concrete storm water culvert. The overall water
quality functions is not affected by the development activity. The wetland is a
Depressional, closed system and impounds surface water run-off from precipitation and
snowmelt events. The entire wetland receives direct untreated storm water Military Rd.
S and from surrounding developed areas of housing and commercial establishments.
The wetland area is surrounded in commercial and residential establishment. It has
palustrine scrub-shrub vegetation and is highly covered with Himalayan blackberry.
Hydrologic
The impacted portion of the wetland will not affect water quality or the bio-filtration
functions. of the entire wetland. The wetland probably receives most of its hydrology
from road run-off during rain and snowmelt events. There is no outlet to the wetland and
it impound water that might otherwise flow to downstream properties.
Habitat
The impacted portion of the Category III wetland provides little or no habitat functions
compared to the overall wetland area. This portion of the wetland is heavily infested with
Himalayan blackberry. Trash and other debris are scattered in this particular location.
In addition, the location is frequently disturbed from noises of vehicular traffic from
Military Rd. S..
20 Midway Samoan Church Mitigation Project October 2021
Table 4. Stream and Buffer Impact Summary.
Location East of 29276 Military Rd S, Federal Way, WA 98003
WA Stream Catalog #
Local Jurisdiction Type F
WRIA 9 (Duwamish-Green
River
DNR Type Type S
Local Jurisdiction
Rating
Local Jurisdiction
Buffer Width
100 ft
Fish Species
NONE .
Description Stream channel is populated with grass and mowed often.
Salmon Stock
Inventory Data N/A
Fish Habitat No aquatic habitat for fish
Stream Channel 15 - 18 ft (bank width)
LWD N/A.
Flow N/A
Riparian/Buffer
Condition
No riparian habitat/stream buffer permanently degraded with housing on the east
side stream bank. Stream bed and bank is predominantly grasses.
Downstream
Fish Barriers N/A.
21 Midway Samoan Church Mitigation Project October 2021
Figure 1. Aerial Photo of Project Site. (King County iMap 2019).
22 Midway Samoan Church Project October 2021
Figure 2. Portion of Category III Wetland (looking North, taken
9/22/2021).
23 Midway Samoan Church Project October 2021
Figure 3a. Stream Condition (Looking N) Figure 3b. Stream Condition (looking S)
(taken 9-22-2021). (taken 9-22-2021).
Figure 4. Panoramic View of the Parcels with the Existing Structures. (Taken 9/22/2021)
Table 1: Property InformationParcel NumberJurisdictionAddressProperty Owner NameContact PersonContact Phone042104-9063; 042104-9032MIDWAY SAMOAN ASSEMBLY OF GOD CHURCHFederal WayLegal Description29276 Military Rd. S., Federal Way, WA 98003253-999-8947PASTOR MATTHEW TAUMUA042104-9032S 11 AC OF THAT POR OF SW 1/4 OF NE 1/4 LY W OF ELY ARM OFDRAINAGE DIST LESS POR WLY OF E MGN MILITARY RD LESS PORSELY OF LN BEG NXN NELY MGN MILITARY RD & DRAINAGE DITCH THNWLY ALG SD RD MGN 248 FT TO TPOB SD LIMITING LN TH NELY INSTRAIGHT LN TAP ON SD DITCH 320 FT NELY OF BEG & END SD LN042104-9063S 220 FT LY N OF & ADJ S 11 AC OF POR SW 1/4 OF NE 1/4 LY W OFELY ARM OF DRAINAGE DIST LESS POR W OF ELY MGN MILITARY RDGOALS AND PERFORMANCE STANDARDS:GOAL•Enhance 1,416 square feet of wetland.•Enhance 8,691 square feet of wetland buffer.•Rehabilitate 5,921 square feet of disturbed buffersPERFORMANCE STANDARDS••After the installation of native plant species, the enhanced wetland will approximatelymeasure 1,416 sq. ft.••After the installation of native plant species, the enhanced wetland buffer willapproximately measure 8,691 sq. ft.••After rehabilitation of temporary disturbance, the area will measure 5,921 sq ft.••Planted species of native vegetation will have obtained the following survivalpercentage of 100% at the end of monitoring years 1 to 5, respectively.••Trees, shrubs, and groundcover species will have ≥ 10% at year 1, ≥ 20% at year 2,and ≥ 35% at years 3 to 5, respectively, after installation.••Non-native invasive species will be eliminated in any monitoring year.PLANT SCHEDULE FOR VEGETATION ENHANCEMENTSCIENTIFIC NAME Rubus spectabilisSalix lasiandraLonicera involucrataCornus sericeaAthyrium filix-feminaCarex obnuptaJuncus effusus Ranunculus repensSambucus racemosaAmalanchier alnifoliaSymphoricarpus albusHolidiscus discolorRosa nutkanaLonicera involucrataGaultheria shallonMahonia nervosaGraminae sp.SYMBOL/SHRUBS Wetland EnhancementSHRUB(SB) Salmonberry(PW) Pacific Willow(BT) Black Twinberry(RO) Red Osier DogwoodGROUNDCOVER(LF) Lady Fern(SS) Slough Sedge(SR) Soft Rush (CB) Creeping ButtercupBuffer Enhancement:SHRUB(RE) Red Elderberry(SY) Serviceberry(SN) Snowberry(OS) Ocean Spray(NR) Nootka Rose(BT) Black TwinberryGROUNDCOVER(SA) Salal(OG) Oregon grape(GM) Grass Seed MixSIZE 1 gal1 gal.1 gal.1 gal.3.5”pot1 gal1 gal4" pot1 gal.1 gal.1 gal.1 gal.1 gal.1 gal.1 gal.1 gal.25-lb bagSPACING 6' On Center6' On Center6' On Center6' On Center6’ on Center6' On Center6' On Center6' On Center8' On Center8' On Center8' On Center8' On Center8' On Center8' On Center8' On Center8' On CenterHand seededQUANTITY6543555615151515101515202 bagsSVSArchitecture LLCPO Box 95142Seattle, WA 98145SVSarchitecture@gmail.comwww.vladsirbu.com(425) 442-3412FEDERAL WAY, WA 98003
MIDWAY SAMOAN CHURCH PROJECT
29276 MILITARY ROAD SOUTHDate: 10-3-202108-16-2021Sheet 1
NEWBUILDING161ST AVE NE86392WETLANDS AREACOMPACTCOMPACT2PROPOSED SEWER LINE[REHABILITATION AREA]FENCE LINEFENCE LINENSCALE:Wetland and Stream Buffer Enhancement Plan 3" = 100'SVSArchitecture LLCPO Box 95142Seattle, WA 98145SVSarchitecture@gmail.comwww.vladsirbu.com(425) 442-3412FEDERAL WAY, WA 98003
MIDWAY SAMOAN CHURCH PROJECT
29276 MILITARY ROAD SOUTH10-3-202108-16-20210'20'40'100'60'80'SCALE:Buffer Planting Plan 6" = 100'0'10'20'50'30'40'SCALE:Wetland Enhancement Area 1' = 100'0'5'10'25'15'20'Sheet 2