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HomeMy WebLinkAboutMisc - folder 1 of 2August 25, 2014
Mrs. Vanessa Dolbee
Current Planning Manager
Department of CED
City of Renton
Renton City Hall -G'h floor
1055 South Grady Way
Renton, WA 98057
..c-F.AVANA
~TR.AILS
Re: Fieldbrook Commons Cul-de-sac
Mrs. Dolbee
UJA !3 -oo i I Ci
CITY OF RENTON
RECEIVED
AUG 2 5 2014
BUILDING DIVISION
Please find enclosed three copies of the proposed cul-de-sac planting plan for the center island
in SE 172"d Street. We chose to utilize plants already in the overall planting plan for landscape
continuity. These are low growing plants and grasses and should not obscure any sight triangles
from the various entry/exit points.
Thank you for consideration ofthis request, please feel free to contact me with any additional
questions or comments.
_:.~ely,) c: ,,/ ~-~
~ers --
Avana Trails, LLC
Avana Trails, LLC
Business Office
9675 SE 36'" Street, Suite 105
Mercer Island, WA 98040
P: (206) 588·1147 F: (206) 588·0954
Sewall Wetland Consultin Inc.
PNW HOLDINGS LLC -FIELD BROOK COMMONS
CITY OF RENTON
Sewall Wetland Consulting, Inc.
27641 Covington Way SE, #2
Covington, WA 98042
MITIGATION PLAN 3-13-2014
NWS-2012-1281
Prepared For:
PNW Holdings, LLC
9675 SE 361h Street
Suite 105
Mercer Island, Washington 98040
Attn: Justin Lagers
March 13, 2014
Job#ll-21
Phone: 253-859-0515
Fax: 253-852-4732
PNW HOLDINGS LLC -FIELDBROOK COMMONS
CITY OF RENTON
1.0 INTRODUCTION
MITIGATION PLAN 3-13-2014
NWS-2012-1281
This report describes the proposed wetland mitigation for the Fieldbrook Commons PUD
project, located on the east side of Benson Road South, and north of Cedar Avenue South
(SE 172nd Street) in the City of Renton, Washington (the "site").
2.0 PROPOSED PROJECT & MITIGATION SEQUENCING
The purpose of the proposed project is to construct a multi-family apartment complex as
the property has been zoned for, as well as planned for in the City of Renton
Comprehensive plan. The need for apartment units within Renton is high and this project
has been proposed to meet that need.
The proposed project is the construction of a 161 PUD project with associated
infrastructure. The location of Wetlands D, E and F result in most of the developable
property on the site being encumbered by wetland or buffer. Since these wetlands,
particularly Wetlands E and Fare of low value, and Wetland Dis small in size but
because of its linear shape impacts the sites usable space so greatly, we are proposing
filling these three wetlands.
As a result, it is our intention to fill these wetlands and provide adequate mitigation for
their lost functions by creating wetland on the eastern side of the site in and around
Wetlands A, Band C. Impacts to wetlands must be justified through a mitigation
sequence as detailed in City of Renton Code. Ideally we would be able to use the King
County fee mitigation banking process as is preferred by the Corps and W ADOE. We
are in agreement that using the fee-in-lieu mitigation option would be ideal and the
easiest/fastest way to mitigate the proposed impacts. However, the City of Renton has
refused to let us use this as a mitigation option as it moves the mitigation area outside the
City limits and in their opinion is a net loss of critical areas to the City. It appears the
City looks at the mitigation, and trail through the buffer as part of the "public benefit"
aspect of this project. The construction of the mitigation onsite, as well as the placement
of a trail through the buffer are being required by the City to allow us to construct this
•
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Sewall Wetland Consulting, Inc,
March 13, 2014
Page 2
project. It is our opinion that the trail does increase the amount of human intrusion into
the wetland, and would be best left off the plan, However, the City of Renton will not
accept this and are forcing us to bring a trail through the buffer regardless of the logic.
The next best option is on-site replacement of the wetland area and functions as proposed
in our mitigation plan.
The attached mitigation plan has been prepared with the recommended documents
elements as requested by Suzanne Anderson of the US Army Corps of Engineers in
previous comments. This plan is prepared in the exact same manner and with the same
information as numerous mitigation plans we have submitted and had approved by the
Corps for various Nationwide as well as Individual Permits. As requested the monitoring
has been modified to include I Oyears of monitoring.
(c) Per the Federal Mitigation Rule, you must provide additional infonnation to
document that a watershed approach to compensatory mitigation was used for the mitigation plan
[33 CFR 332.3(c)]. A link to Wdland Mitigation Situ Using a Watershed Approach, Ecology
Publication #09-06-032 is available from our webpage at www.nws.usace.army.mil, select
"Regulatory Branch, Permit Information", then "Mitiption Resources", then "Mitigation Tools".
We recommend that you dcmonstratc that the chosen mitigation site satisfies criteria in Charts 2
and 3 of the site selection guidance (i.e., identified as a site with potential and that is
sustainable); and that it satisfies criteria in Charts 4 through 11 for the appropriate fimctions.
Using Chart 2 from the Watershed approach which is an analysis utilized to pick a
mitigation site is not really applicable, as the City of Renton is requiring we conduct the
mitigation on the site where the impact is occurring. In addition, there is no other
available mitigation sites within this drainage basin that is owned by either the City or the
client for use as a mitigation receiving site. Therefore, mitigating on-site is the only
feasible alternative given these constraints.
In regards to Chart 3;
Question 3A: Identify the watershed processes that have been altered within the hydrologic
unit where the mitigation site is located.
Human activities can change watershed processes by changing water flows; introducing
nutrients, pollutants, non-native species, and sediment; and by fragmenting habitats.
Changes in these processes often create problems that can be improved through mitigation
activities. To begin you need to identify the major landscape-scale problems (i.e., alterations
to processes, not structure) that exist in the hydrologic unit where your site is found This will
help you identify which restoration or enhancement actions will be the most effective in that
hydrologic unit. Check the appropriate column in the following table to identify problems
that might exist. The last column notes if the altered process has already been identified in an
existing watershed plan as a problem that needs to be addressed
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Sewall Wetland Consulting, Inc.
March 13,2014
Page 3
The current flooding events within the Soos Creek drainage are generally not increasing due
to the current use of modem storm water facilities within the basin. However, there still is
some increase as there is more water getting to the basin faster in storm events.
There is less eutrophication in rivers and streams in the basin primarily from removals of
livestock and old septic systems.
Water quality has been reduced in the basin to a degree.
Some stream and bank erosion does occur within the basin.
Habitat has become more fragmented as the area's population grows and more development
occurs.
Question 3B: Will the mitigation result in a wetland of the appropriate hydrogeomorphic
(HGM) class for the landscape setting?
Wetland mitigation sites are sustainable only if the type of wetland being proposed is
appropriate for its position in the landscape. The HGM classification of wetlands is based on
characteristics of water movement and position in a landscape. Therefore, it can be used to
identify appropriate wetland types for different locations in a hydrologic unit.
Yes, we will be mitigating for depressional wetlands with a depressional wetland
mitigation area.
Question 3C: Will the primary source of water to the mitigation site be appropriate for the
HGMclass?
Groundwater and direct precipitation will be the source of hydrology for the wetland
mitigation site as was the source for the impacted wetlands. Hydrologic monitoring of the
mitigation site has shown that surficial groundwater elevations in the mitigation area will
sufficiently hydrate the creation area with soils saturated to the surface and some standing
water in the growing season.
Question 3D: Will the site have an adequate supply of water to maintain a wetland without
engineering the delivery of water that would require long term control or maintenance?
The surficial groundwater monitoring and proposed grades should create a wetland area that
will require no additional or artificial source of water to maintain its viability. It is thought
that Wetland A which is located within the area ofan old mine is discharging water from
historic mining and as such there is an abundant supply of water in this area.
Question 3E: Will the mitigation activities maintain hydric soils, if they exist, at the site?
Removing hydric soils can decrease the potential for success of wetland restoration. Hydric
soils often contain a seedbank of wetland plants that supplement any planting you may
propose.
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Sewall Wetland Consulting, Inc.
March 13, 2014
Page 4
Hydric soils from the filled wetlands will be mixed with topsoil and utilized in the newly
created wetland maintaining viable seedbanks.
Question 3F: Can the mitigation be designed to control aggressive plant species?
There is currently not a predominance of aggressive invasive or weedy species in the area
of the proposed mitigation or the two wetlands that will be connected together with the
creation. Standard invasive species control will be utilized in the mitigation area which
has proven successful in other mitigation sites.
Regarding the appropriate Charts 4-11;
Chal't 5: <:nJal -lwproYiug Hydrology Fundiom iu Depres~ioual 5ystt'-tm Outsidt' of Flood1>laios
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Sewall Wetland Consulting, Inc.
March 13, 20 l 4
Page 5
Ch,irt 7: Goal~ Imprnving,\·at~r Quality ("-Q) Ftm<'tiom in Dep1·es<;ional .Sy~tNm Outi;icte of floodplain,;. -..
.;·eersr·_'zt~
Cal .............. ,. ---..
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( linrl HI: Goal -hnprolillg SpE-cies Ridme,s of Wildliff-~...,..._
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Slll'fxe po,tdina: wil itllpKt the
lfbutlutioR .t pllMS • '1M In
(sa lo llelCt question I
Ch.iri] 1: (nJal -Impro\ing Spl'des Rkhnes;; of Plants --
.-,.. -. ···-n>
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Fieldbrook/#11-121
Sewall Wetland Consulting, Inc.
March 13, 2014
Page 6
.. ., . .,.... ......... _
~~= 5U,a,lt,
auT e,ian •ust daolbl !low
COMlt..Uat ltte ~ ,cai.
wtlN.-...ci.
(Flo Mn .,.nion)
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IIMl!lwriltltlew~-"'-"ffil; .. . ..._; ... _....,,._, ...... .....,..,._ ....
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This sequencing requires addressing the following criteria;
a. Avoid any disturbances to the wetland or buffer;
~-. ~ ,_,.-... ffl'.i'lilla ... ,,.,.,,..-,...1
e-1e1..,._....,. ... .,_,,. iocl,..,_......,.,_ics __ , 1'9Ml'-IMrlwi-.-...-....""11d,i ....
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~.iPoNi,e,ityN ~SI.CUISl..u/ ==._~::..,,~·=::: --
The site contains three small wetlands which the developer proposes to fill and mitigate
for through the creation of a new wetland area and enhanced buffer areas for the existing
and remaining wetlands A, B & C in the eastern third of the site. Wetland F located on
the western side of the site is Category Ill wetland measuring l 595sf. Due to the
requirement to provide a secondary fire access directly out to I 081h Ave S.E. the
developer is unable to avoid direct impact to this wetland. Wetland E, located in the
center of the site and adjacent to S.E. l 72"d St. measures 68sf and is rated as a Category
IV wetland. Due to the requirement to dedicate and construct the other half of the S.E.
l 72"d St. ROW the developer is unable to avoid direct impacts to this wetland. Wetland D
is located generally in the center of the project and is rated as a Category III wetland
measuring 7671 sf.
b. Minimize any wetland or buffer impacts;
The developer previously attempted to plan roadways and improvements around Wetland
D, however the location and shape of the wetland impacted the vehicular circulation and
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March 13, 2014
Page 7
building locations to such an extent that the project would not be financially feasible to
construct.
c. Restore any wetlands or buffer impacted or lost temporarily; and
Restoration of Wetland Din this location would not be feasible due to the location of the
impacts and configuartion of the parcel and remaining wetland.
d. Compensate for any permanent wetland or buffer impacts by one of the following
methods:
i. Restoring a former wetland and provide buffers at a site once exhibiting
wetland characteristics to compensate for wetlands lost;
This is not applicable to this site as no historic wetlands are located on the property.
ii. Creating new wetlands and buffers for those lost; and
A total of9,334sf of wetland will be filled.
US Army Corps of Engineers Required Mitigation
Using the recommended ratios from Table 1 a, of the W ADOE Publication Wetland
Mitigation in Washington State Part 1, (WADOE March 2006 Pub. #06-06-01 Ja)
Table 1
Wetland Size Category Vegetation Ratio Required
Type Wetland
Creation
D 767 lsf Ill Forested 2:1 15342sf
E 68sf IV scrub-shrub 1.5:1 102sf
F 1595sf lll scrub-shrub 2:1 3 ! 90sf
Total 9,334sf 18,634sf
As described above, based upon the required USA COE and W ADOE ratio, a total of
18,634sfofwetland is required to be created.
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March 13, 2014
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The proposed mitigation will create 25,430sf of wetland, which exceeds the required
USA COE ratios by 6, 796sf. The extra wetland being created over the W ADOE
recommended ratios is a result of the City of Renton having a higher mitigation ratio
requirement than the Corps.
As seen in Table 2 below, using the three main functions from the W ADOE Rating
System recognized by the Corps, a substantial functional lift will be attained from the
connection of Wetlands A and C with 25,430sf of additional wetland over the existing
functions of the proposed fill wetlands.
Table 2. Functional Comnarison of imnact wetlands and nronosed miti ation
Wetland Area Flood Species Water Hydrologic Habitat
Storage Richness Qual. Function Function
canacitv Function
Category
Wetland D 7671sf 3800cufi 5 svecies 12vts 8nts 13vts III
Wetland E 68sf 34cufi 2 snecies lints 4vts IOvts
Wetland F 1595sf 500cuft 5 svecies 20vts 8vts 11 vts
Pronosed 25430sf 7600cuft 15 species 24ots 20pts 21 pts
Functional +16096sf +3266cuft +8species* +9pts +12pts avg +9pts
l Lift av2 av2
*only 7 different species were found (excluding exotic/invasives) in Wetlands D, E &F
The newly created wetland will connect to existing Category III wetlands (Wetlands A
and C) and provide enough lift that this wetland will now be considered a Category II
wetland under the W ADOE rating system. This is a substantial lift in function, surface
water storage and species richness over the fill of Wetlands D, E & F, which are
generally low value Category Ill and IV wetlands.
Hydrologic monitoring of mitigation site and general construction overview
IV
III
II
+1
Cate2orv
To compensate forthe impact to 9,334sfofCategory III & IV wetland, we will create
25,430sf of wetland between Wetlands A and C. This results in an overall wetland
mitigation ratio of2.72:l (createdwetland:impactedwetland). This mitigation will
create Category I! wetland for a combination of Category Ill and IV wetland impacts. As
depicted on the attached Final Mitigation Plan, 25,430sf of area will be excavated out to a
similar depth to the existing wetland in two areas to intercept the surficial groundwater
table and create conditions favorable to create wetland hydrology.
A series of 6 monitoring pits/wells were located within the proposed wetland mitigation
area. These were monitored with weekly site visits from April of2012-August 2012 as
well as March and early April of 2013. At each of these points soil saturation and water
table levels were measured to determine what surficial groundwater elevations are, to
facilitate designing grades for the new wetland creation area. What we found was that
within the proposed creation area, groundwater levels in the early growing season area
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March 13, 2014
Page 9
between 14" -30" below the existing surface (see table below). It is assumed in the very
early growing season (February and March) the groundwater elevations are shallower
than the measurements we took, meaning the groundwater elevations are closer to the soil
surface.
As shown on the attached Final Mitigation Plan Sheets Wl -W3, we utilized these
existing groundwater contours to create the new grades for our mitigation site. As can be
seen by the grades and associated cross-sections, the grades will remove soil down to the
existing groundwater elevations to create wetland areas with soils saturated to the surface
for the early growing seasons, to also include flat areas that will hold some shallow l "-3"
of surface water to provide a variety of wetland hydro logic regimes from saturated, to
seasonally flooded. The fact that the excavation is being brought to the higher levels of
groundwater within the growing season, and will not cut into the surficial groundwater
table, should alleviate the concern of intercepting and draining off this water. All we are
doing is removing the surface soil above the existing sloping groundwater table to make
those saturated soils closer to the surface. Soil disturbance of the groundwater retaining
portion of the soil column will not occur.
Although creation of a slope type wetland is not the most conventional or common
mitigation method, it is a feasible method of wetland creation when conditions warrant its
use. Our company has been involved in two larger wetland creations using this type of
concept, most recently a 3 acre wetland creation with over IO' of vertical drop across the
landscape in sloping of the creation area (see Snohomish County Parks Centennial Trail
II mitigation plan reviewed and approved by Jonathan Smith of the Corps). By using the
same method of removing soil down to the level of the highest groundwater elevations as
is proposed in the Fieldbrook project, we successfully created a 3 acre sloping wetland in
the previously described project.
Table 3. Groundwater elevations below surface o ,. hvdrolo· "monitorinP noints 2012
Monitor DATE
point&
elev.
4/13 4/27 5111 5/24 617 6/28 7/12
A417.5' -15 -14 -15 -20 -26 drv drv
B418' -17 -16 -16 -22 -27 drv dry
C417' -20 -18 -17 -20 -25 dry drv
D416.5' -14 -14 -14 -16 -20 drv drv
E418.5' -27 -26 -24 -30 -36 dry drv
F418' -21 -22 -20 -28 -36 drv drv
Note: All elevations indicate the elevation of the saturated capillary fringe of soil
saturation observed in hydrology monitoring points.
8/12
drv
drv
dry
drv
drv
drv
Table 4. Groundwater elevations below surface o
Monitor DATE
point&
elev.
3/15 3/29 4/9
A417.5' -12 -I 0 -15
B418' -15 -15 -14
C417' -17 -16 -18
D416.5' -10 -11 -13
E418.5' -23 -20 -23
F418' -18 -19 -20
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March 13, 2014
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r hvdrolo• "monitorin2 points 2013
Note: All elevations indicate the elevation of the saturated capillaryfringe ofsml
saturation observed in hydrology monitoring points.
. . . . . . ,,. . . . ..
. . : : : : : : : : : : ;;:: ~:::::::::.
• 0 • 0 • + • I ' + • + J',A• • + • ;.:·, • 0 ' o O + + o o .. . ............. · .... /'.. . . . ...
••••••••••••• t ••••• • .. ~ •••••••••••
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March 13, 2014
Page 11
419A~~~__:__;W'---~~-EnsM~· _$,,.,_'"-ifa<,~~~~~~~~~--=;B
lli~I ~~~~~t~~~~...,~.;J,~~~s.~~~~~~~~~~~2~~~~1
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A small berm will be placed between the wetland creation area and Wetland B. This will
prevent (in the unlikely case of surface water overtopping the edge of the wetland) the
wetland creation area between Wetlands A and C from draining into Wetland B.
Hydrologic monitoring will be conducted using peizometers in the proposed mitigation
area through the winter and spring to verify groundwater elevations. This area will then
be graded back at a slope no steeper than 3:1 (horizontal:vertical). The area will then be
planted with a mix of native trees, shrubs and herbaceous species and will also include
several habitat features (logs and snags) to increase its habitat function.
As depicted on the attached Fieldbrook Commons Mitigation & Grading Plan (dated 9-
23-13), a split rail fence will be placed at the edge of the wetland buffer. There are no
living spaces or recreational space next to the wetland or its buffer limiting use of this
area. However, the City of Renton is requiring that the applicant provide a trail through
the wetland buffer as depicted on the plan. We have moved this trail to the north,
splitting the buffer area between the wetland creation area and Wetland B to the north to
maximize distance of the trail from the wetland as best possible.
Signage and a split rail fence along the trail indicates the character of the critical area and
will discourage intrusion into the wetland or buffer.
All lighting will be located outside the wetland and buffer. All lighting in the developed
portion of the site will be directed away from the wetland and its associated buffer.
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The goal will be to create at least 25,430sf of area meeting all three wetland criteria
(hydric soils, hydrophytic vegetation, and wetland hydrology) as specified in the
Washington State Wetlands Identification Manual (W ADOE, March 1997) and the
Western Mountains, Valleys and Coast region Supplement (Version 2.0) dated June 24,
20 I 0. All disturbed buffer areas will be restored with a dense planting of native trees and
shrubs. The resulting wetland creation area will be monitored for IO years. The creation
area will be delineated at Years 5 and IO to determine if 25 ,430sf of area meeting
wetland criteria has been created. If there is not at least 25,430sfofwetland created, the
shortage will be made up with either;
I. Fixing any small grading or hydrology issue which may be impacting the overall
size of the creation area, or;
2. Purchase of mitigation credits from the King County Fee program or other similar
program at that time.
Site Protection Instrument
The entire mitigation site as well as the buffer and undisturbed wetlands will be placed
within a Native Growth Protection Easement (NGPE) and recorded on title prior to
occupancy of the project.
Long Term Maintenance
The mitigation area will be monitored and maintained over the IO year monitoring
period. This will include trash removal, weed and invasive species removal, repair of
fencing and signage. After the required IO years maintenance and monitoring period, the
facility operating manual will include a description of the NGPE are and what type of
maintenance can and should occur within this area. Management of the facility will be
responsible for this work following the IO year monitoring and maintenance period.
Fieldbrook/#11-121
Sewall Wetland Consulting, Inc.
PROPOSED MITIGATION
1.0 MITIGATION PROJECT OVERVIEW
March 13, 2014
Page 13
To compensate for the fill of a 9,334sf Category Ill & IV wetlands, it is proposed to
create 25,430sf of wetland between Wetlands A and C. Wetlands to be filled include
Wetland D (7,671 sf Category II] wetland), Wetland E (68sf Category IV wetland) &
Wetland F (l,595sf category II] wetland).
2.0 MITIGATION GOALS
2.1 Mitigation Goals
The mitigation proposal is to connect Wetlands A and C with an area of25,430sf of
wetland. The wetland creation areas will be densely planted with native vegetation. The
use of diverse native plantings are expected to significantly improve the overall function
of the wetland and buffer as it will remove dense thickets of exotic blackberry as well as
add emergent and shrub plant communities into what is now, a single class forested
wetland.
2. 2 Mitigation Goals
2.2.1 Create 25,430sf of emergent, scrub shrub and forested wetland.
3.0 CONSTRUCTION SEQUENCE
The construction sequence of this project will be implemented as follows:
3. I Pre-construction meeting
3 .2 Construction staking
3.3 Construction fencing and erosion control
3.4 Clearing and grading
3.5 Stabilization of mitigation area
3.6 Plant material installation
3. 7 Construction inspection
3.8 Agency approval
3.9 IO year Monitoring inspection and reporting
3.10 Silt fence removal
3.11 Project completion
3.1 Pre-construction Meeting
A pre-construction meeting will be held on-site prior to commencement of construction,
to include the biologist, the City, and the contractor. The approved plans and
specifications will be reviewed to ensure that all parties involved understand the intent of
the construction documents, specifications, site environmental constraints, sequences, and
inspection requirements.
3.2 Construction Staking
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The limits of clearing and grading near the critical areas will be marked in the field by a
licensed professional land surveyor prior to commencement of construction activities.
3. 3 Construction Fencing & Erosion Control
All erosion control measures adjacent to the critical areas, including silt fencing and
orange construction fencing, will be installed. Erosion control fencing will remain
around the mitigation area until clearing, grading and mulch placement are complete in
upland areas outside the critical areas.
3.4 Clearing & Grading
Clearing and grading in and near the existing sensitive area will be per the approved Final
Mitigation Plans.
3.5 Stabilization of Mitigation Area
All graded areas in the wetland or buffer will be stabilized with mulch upon completion
of grading. Orange construction fencing and erosion control fences will be restored (if
necessary) and placed around the critical areas.
3.6 Plant Material Installation
All plant material will be planted by hand per detail and Construction and Planting Notes.
The Mitigation Plan specifies the required size, species, quantity, and location of plant
materials to be installed. The contractor will mulch areas disturbed during the planting
process. Upon completion of the planting, the erosion control fencing will be restored
and repaired. Plant substitutions or modifications to locations shall be approved in
writing by the Owner's biologist prior to installation.
3. 7 Construction Inspection
Upon completion of installation, the biologist will conduct an inspection to confirm
proper implementation of the Mitigation Plan. Any corrections, substitutions or missing
items will be identified in a "punch list" for the landscape contractor. Items of particular
importance will be soils in pits, pit size, plant species, plant size, mulch around pits, and
tree staking.
Upon completion of planting, if installation or materials vary significantly from the
Mitigation Plan, the contractor will submit a reproducible "as-built" drawing to the
Owner. The As-built and installation sign-off report will be submitted to the Corps at
that time.
3.8 Agency Approval
Following acceptance of the installation by the City, the City biologist should prepare a
letter granting approval of the installation.
•
3.9 Monitoring
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March 13,2014
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The site (wetland creation, buffer enhancement, buffer restoration and areas of temporary
disturbance) will be monitored for IO years to insure the success of the mitigation project.
If additional years of monitoring are required by the Corps, the plan will be revised to
reflect this change. Any areas of temporary impacts that require restoration will be also
monitored for the full 10 year monitoring period.
3.10 Silt Fence Removal
Erosion control fencing adjacent to the mitigation area will remain in place for at least
one year, and/or until all areas adjacent to the mitigation area have been stabilized. The
City's Biologist may recommend that the fencing remain in place for a longer duration.
4.0 CONSTRUCTION AND PLANTING NOTES
4.1 Site Preparation & Grading
4.1.1 The Landscape Contractor will approve existing conditions of subgrade prior to
initiation of any mitigation installation work.
The Landscape Contractor will inform the Owner of any discrepancies between the
approved construction document and existing conditions.
4.1.2 The General Contractor will flag the limits of clearing with orange construction
fencing and will observe these limits during construction. No natural features or
vegetation will be disturbed beyond the designated "limits of clearing".
4.1.3 The Landscape Contractor will hand grub all non-native invasive plant species
including the removal of root crowns. These species may include, but are not limited to
Himalayan blackberry, evergreen blackberry, English ivy, and English holly. Weed
debris will be disposed of off-site.
4.1.4 The wetland area will be excavated to the depths shown on the Final Mitigation
Grading Plan and brought to final grade with 8" of topsoil. The biologist will be on-site
to confirm the grading is acceptable for planting. A total of 4" -6" of compost will be
incorporated into the upper 12" of all graded areas in the wetland creation area.
4.2 Plant Materials
4.2.1 All plant materials will be as specified in the plant schedule. Only vigorous
plants free of defects, diseases and infestation are acceptable for installation.
4.2.2 All plant materials will conform to the standards and size requirements of ANSI
260.1 "American Standard for Nursery Stock". All plant materials will be native to the
northwest, and preferably the Puget Sound Region. Plant materials will be propagated
•
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March 13, 2014
Page 16
from native stock; no cultivars or horticultural varieties will be allowed. All plant
materials wi II be grown from nursery stock unless otherwise approved.
4.2.3 No balled and burlapped, or bare root plantings will be used. Only container
stock to be used.
4.2.4 All plant materials stored on-site longer than two (2) weeks will be organized in
rows and maintained by the contractor at no additional cost to the owner. Plant materials
temporarily stored will be subject to inspection and approval prior to installation.
4.2.5 Substitution requests must be submitted in writing to the Owner and approved by
the Owner's biologist in writing prior to delivery to site.
4.2.6 All plant materials will be dug, packed, transported and handled with care to
ensure protection from injury. All plant materials to be stored on site more than 24 hours
will be heeled into topsoil or sawdust. Precautionary measures shall be taken to ensure
plant materials do not dry out before planting. Wetland plants will be shaded and
saturated until time of installation. Immediately after installation the mitigation planting
area will be saturated to avoid capillary stress.
4.2.7 The contractor will verify all plant materials, the quantities shown on the planting
plan, and the plant schedule. The quantity of plant materials shown on the plan takes
precedent over the quantity on the plant list.
4.3 Plant Installation
4.3.1 All plant materials must be inspected prior to installation to verify conformance of
the materials with the plant schedule including size, quality and quantity. Any plant or
habitat materials deemed unsatisfactory will be rejected.
4.3.2 All plant materials delivered and accepted should be planted immediately as
depicted on the mitigation plan. Plant materials not planted within 24 hours will be
heeled-in. Plant materials stored under temporary conditions will be the sole
responsibility of the contractor. Plants will be protected at all times to prevent the root
ball from drying out before, during, or after planting.
4.3.3 All planting pits will be circular with vertical sides, and will be sized per detail on
the mitigation plan and filled with pit soils approved by the Owner's biologist. Planting
pits shall not be deeper than the root ball. If native soils are determined to be
unacceptable by the Owner's biologist, pit soils will be amended with Cedar Grove
mulch or equivalent.
4.3.4 No fertilizers will be used within the wetland. In buffer areas only, install
"Agriform", or equal plant fertilizer to all planting pits as specified by manufacturer.
Fieldbrook/#11-121
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March 13,2014
Page 17
Fertilizers are allowed only below grade in the planting pits in the buffer areas. No
sewage sludge fertilizer ("SteerCo" or "Growco") is allowed in the mitigation area.
4.3.5 All containerized plant materials will be removed from their containers carefully
to prevent damage to the plant and its roots. Plants removed from their containers will be
planted immediately.
4.3.6 All plant materials will be placed as shown on the approved mitigation plan. If
the final installation varies from the approved mitigation plan, the contractor will provide
a reproducible mylar as-built of the installed conditions. All plant material will be
flagged by the contractor.
4.4 Planting Schedule and Warranty
4.4.1 A fall-winter installation schedule (October I st -March 15th) is preferred for
lower mortality rates of new plantings. If plant installation occurs during the spring or
summer (March 15th -Oct. I st) a temporary irrigation system will be required, unless
the area can be sufficiently hand-watered.
4.4.2 All disturbed areas will be protected with an arborists mulch to a minimum depth
of six inches.
4.4.3 The installer will warrant all plant materials to remain healthy and alive for a
period of one year after final acceptance. The installer will replace all dead or unhealthy
plant materials per the approved plans and specifications.
4.5 Site Conditions
4.5.1 The installer will coordinate with the Owner and the Owner's biologist for
construction scheduling.
4.5.2 Landscape installation will begin after the City acceptance of grading and
construction. The Owner will notify the Owner's biologist of acceptance of final
grading.
4.5.3 Silt fences will be installed as shown on the approved mitigation grading plans.
The installer is responsible for repair and replacement of silt fences disturbed during
plant installation. No equipment or soils will be stored inside the silt fences.
4.5.4 After clearing and grading is complete in the mitigation area, exposed soils will
be seeded or mulched. Orange construction fence will be placed around the mitigation
area to prohibit equipment and personnel in the mitigation area.
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March 13, 2014
Page 18
4.5.5 Final grading will be based upon soil conditions found during excavation of the
mitigation area.
4.5.6 All plant material will be planted with suitable soils per planting details. Soils
from planting holes will be spread and smoothed across the mitigation area.
5.0 MAINTENANCE PROGRAM
This maintenance program outlines the program, procedures and goals for mitigation of
the stream and buffer impacts at the mitigation site. This maintenance program will be
the responsibility of the project owner through the duration of its ownership of the
mitigation area, or throughout the duration of the monitoring period, whichever is longer.
The maintenance contractor will complete the work as outlined below.
5.1 Maintenance Work Scope
5.1.1 To accomplish the mitigation goals, normal landscaping methods must be
modified to include:
a.No mowing or trimming of ground cover or vegetation in the mitigation
area.
b. No placement of fertilizers in the mitigation area.
c. No placement of bark mulch or equivalent in the mitigation area,
except as noted in the planting details.
d. No placement of grass clippings, landscape debris, fill or ornamental
plant materials in the mitigation area.
5.1.2 Work to be included in each site visit:
a. Remove all litter including paper, plastic, bottles, construction
debris, yard debris, etc.
b. Remove all non-native and invasive species identified in Table 3-1 of
Sheet W-3 of the Final Mitigation Plan within the mitigation area. All debris is to be
removed from site and disposed in an approved landfill.
c. Repair silt and/or permanent fencing and signage as needed.
5.1.3 Work to be completed on an annual basis includes:
a. Areas containing non-native/invasive species identified in Table
3-1 of Sheet W-3 of the Final Mitigation Plan should be controlled by hand cutting and
removing the root crowns for species such as Himalayan blackberry. Following hand
removal, treating re-sprouting invasive/non-native species with a glyphosphate herbicide
such as Roundup or Rodeo by a licensed applicator can be utilized.
b. Replace dead or failed plant materials. Replacement plantings are to be
of same species, size and location as original plantings. Plantings are to be installed
during the dormant period.
5.2 Maintenance Schedule
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Page 19
The Owner will conduct all items listed in the Maintenance Work Scope on an annual
basis. Additional work may be required per the Monitoring Report and as approved by
the Corps. Additional work may include removal of the grasses around each shrub and
tree, installation of wood chips at each shrub and tree base and erosion control protection.
5.3 Watering Requirements
5.3.1 Watering with a temporary irrigation system will be required during the first
spring and summer after the installation. The temporary irrigation system may be
removed after the first year providing the plantings are established and acclimated to on-
site conditions.
5.4 Close-out of Ten-Year Monitoring Program
Upon completion of the monitoring program and acceptance of the wetland mitigation by
the Corps, the maintenance of the project will be reduced to include removal of litter and
debris, repair of perimeter fencing and sign age, removal of noxious weeds and
undesirable vegetation, and repair of vandalized areas.
6.0 WETLAND AND BUFFER 10 YEAR MONITORING PROGRAM
6.1 Sampling Methodology
The created wetlands and their associated enhanced and restored buffers as well as areas
of temporary disturbance will be monitored once per year over a ten-year period, starting
with the first year after the plants have been installed, and as required by the Corps.
Monitoring will be conducted using the techniques and procedures described below to
quantify the survival and relative health and growth of plant material. A monitoring
report submitted following each monitoring visit will describe and quantify the status of
the mitigation at that time. Vegetation monitoring will be conducted in August or
September during monitoring years. Year 1 monitoring will occur at least one calendar
year after installation sign-off.
6.1.1 Hydrology
Wetland hydrology will be monitored using seven (7) piezometers per USACOE
specifications. These will be located within the restoration area to be placed at the time
of the installation sign-off by the biologist. Surface water level or ground water
saturation depths will be measured at these stations to determine if wetland hydrology has
been successfully attained. As is noted in the Corps of Engineers Wetlands Delineation
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March 13, 2014
Page 20
Manual (Environmental Laboratory, 1987) and the Western Mountains, Valleys and
Coast region Supplement (Version 2.0) dated June 24, 2010, wetland hydrology is
defined as inundation or soil saturation ( usually within 12" of the surface) during the
growing season. The growing season for this area is generally defined as the period
between the middle of March and the middle of November. However, plant growth often
occurs earlier in the year and sound professional judgment will be needed to determine
when the growing season is taking place at the site. Hydrology will be monitored twice a
month from March I st through May 30th of each year.
Wetland hydrology will be considered successfully created if wetland hydrology is
observed inundating or saturating the soil within 12 inches of the surface during the
growing season
6.1.2 Vegetation
The vegetation monitoring consists of inspection of the planted material in late summer
or early fall (August-September) to determine the health and vigor of the installation, as
well as coverage estimates. All the planted material in the wetland and buffer will be
inspected during each monitoring visit to determine the level of survival of the
installation.
All plants will be inspected and recorded as to whether they are alive or dead based upon
the "as-built" in Years I & 2. In Years 3-5, coverage estimates will be used to determine
success of the vegetation component.
A total of 27 permanent 3.0m rectangular monitoring plots will be located within the
mitigation area as depicted on Sheet W-3 to monitor shrub and tree species coverages.
Within each of these 3.0m plots, the emergent plant community coverage of vegetation
will be measured with 0.25m rectangular plots. Estimates of coverage percentages will
be made within these plots.
Photographs of the mitigation area will be taken from 6 photo points to be located during
the installation sign off as well as at each permanent monitoring plot. Photographs will
be taken at each of the monitoring and included with the monitoring report for each year
from these points.
During years l & 2 of the monitoring, replacement plants as well as dead plants will be
flagged with distinctive flagging to distinguish what plants these are.
Fieldbrook/#11-121
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Page 21
6.2 STANDARDS OF SUCCESS
TABLE 3-1: PERFORMANCE STANDARDS
1T!M ftAIIS TO K MONITOMD ........._,.,,,..,...
WITlANO HYDROlOGV Y£AltS 1, 2, 3, 4, 5, 7 ANO 10 SOll5 WITHIN CJIEATW wtll.AND AREAS SHAll IE SATUAATCO TO TH( SUflfACt, HAvt SHAJ..LOW
jCfl;E,1,ltO WlTLANO ANO GflOUNOWATEII mstNT WITHIN 12 INCHn OF THE SOIL SUJIFACE, M!!?L2.'! HAVE SLl'IFACE PONDING
WUIAND A/WliTLAND C} PRU£NT FOR AT I.WT FOUR 14) CO"JS,£CUT1Vl MUS DUIIIN<i TH( GM)WING SEASON WHEN RAINF.W.IS
L!SS THAN OR. EQUAl TO THE MEAN FOR THe PEIUOO Of AVl'Jt.Allf RECORD.
wrnANO DELINEATION 't£ARS 5 AND 10 PE .. FORM DEUNEAnoN OF WETLAND A, WHI.ANO C, ANO WETLAND CREATION JINA TOOHElMINE IF
WHtTHEk WHtAND A A~WHLANO C Ml o\FffCTEO BY H4E WU\ANO c«EATION. n:~ .. MANCE
STAHDAAO ISSA.TISAEO IF TltEIU IS NO CHANGE TO WfllAJ\10 tlMITS.
AATMVEGETATION YEARS 1, 2, J, 4, 5, 1 AND 10 TREE AND SHRUB SPECIES
(<:«EA.TEO WETlNID/ {TO OCCUR IN AUGUST Oft . ioo,i.5Ullvlv4 jy iNSTAUEO PLANT STOO: Amil THE FIii.ST GROWiNG SEASON .
ENHANCED WEfl..ANO 8UFFEIIJ Sff'ltt.4SER KGIN..iNG ON[ . eo,(. S~\/Al BY INST.Jill ED PLANT 5100: AFTER Ttlf SECOND GIi.OWiNG SEAS<»! .
VEAR FOLLOWING INITIAL . INHANaD IIUffU f'lANTING AUAS: MINIMUlll rfllCfNT 00V£R IY TRffSANO Sl'IRUIIS:-Vf.U J:
,LANT INSTALlATl'.>N.) ~; Y£AR S: •'516: ViAll 7: &5%; Vl.U IO:'°"· UP TO 20%0f TttE HAT!VE 'WOOOY l't.ANTSJ'fCIES
COVERAGE MA't' 9£ COMPRISED Of Df$HtA&1.E NATM (OlONIZING SP£0£S. . AFTER THE FIFTH GROWING SEASON, A MlMMLIM Qi: FOUR. OIFFElENT l'tANT SPEOES Will
COMPR!St: GflEATU THAN 1<1% COVERAGE. . atlAllD WfT\AND NANTINI MEAS: M!HIMUM ,ERCENT COYER l't' ill ES ANO SHRU!S: YEAJI; 3:
~; 'tfAA S: ~; YUR 7: ~; 't'UR 10: 90%. U,TO ~OF THE NATIVE 'WOOO't' Pl.AHTSPECIES
covalAGE MAY Ill COMl'1'1$EO Of OEstll.AllE MATIVE COlONIZINGSPEOES.. . AFTI:ll THE FffTft GftOWtt.lG SEASON, A MINIMUM OF FOUR DIFFERENT ,l.ANT SPEms WILL
COMPRl$f. GREATER fHAN 10% COYEAAGE.
EMERGENT SPECfES . :!Si Avtildt COVERAGE l't' INST4llEO PL4NT STOO: AFTER THE Flf\ST GROWING S£ASON . . 8°"AVEAAGE COVERAGE IY IHSTAWO PLANT STOO:AFTER THI 5TH ANO 7TH GROWING SEASON . . ~AVERA6E COVERAGE IY NATM EMERGENT ,I.ANT ioPEOES AFTER THE UNTH GROWING SIMON • . AFTER TliE FIFTH GROWING SEASON, A MINtMUM OF Ttll{ff OlffERENT PLANT S,E<:1£5 Will
COMPfUSE GQA.Tlll. THAN 1°"" COVl:AAGE.
NAT!Vi W.GHATION vtAAS 1, 1, 3, 4, S, 7 AND 10 . 100% SUR'/lVAL IY INSTAJ.110 PLANT STOO:AflER THE FlllSf GROWING YASON .
{RESTORED WE HANO 9Uff£R (TOOCCUR-..AUGUSTOR . BOK SURVIVAL IV INSTAillO PLANT STOCK AFTER THE HIRD Gl\owtNG S£ASON .
ANO Al\[ASOfTEMPOMRY HPTIMM.I\ IEGINHlNGONE . MINIMUM l'fRCENT COi/ER IY TREES .ANO SIUIU6S: VEAR 3: 30%; 't'EAlt 5: 45-%; 't'EAR 7: 6S'lli; ~ 10:
D1STUfl5ANC!} YEAR fOllOWIHG 1NlTlAl IO'K. u, TO 2°" OFTHf NATM: WOOOV l'lANT S,fOfS COVIRAG£ MAV If COMPIUSfD or
PlANT INSTAI.LATION.) DESIAA!LE NATh'E COt.ONtZJNG SPEQl;S. . i\FltR THE FIFTH GROWING SlASON, A MINIMIM OF FOUR DIFFERENT PLANT SPEOES Will
COMPAISf: GRtATIR THAN 10'6 COVERAGE.
NOXIOUS WEED SPECIES YEARS J, 2, 3, ,, S, 7, ANO 10
USS THAN l°"COVfllAGE IVAI.LCWS "A", "l",AHD"C" NOXIOUSWE£DS(l~UDINGNON-REGUI.ATt0
"II" ANO "C" NOXIOUS WHOSt 10£NTIFl(0 ON THf lATIST KING COUNTY NOXIOUS Wt:!O UST. NOXIOUS
WEED CONTROL ~MORMANC£ STANDARDSMtf LMTED TO PI.AN'l'ED NlfAS ONLY.
7.0 CONTINGENCY PLAN
7.1 A contingency plan can be implemented if necessary. Contingency plans can
include re-grading, additional plant installation, erosion control, modifications to
hydrology, and plant substitutions including type, size, and location.
7 .2 Careful attention to maintenance is essential in ensuring that problems do not
arise. Should any of the site fail to meet the success criteria, a contingency plan will be
developed and implemented with the City approval. Such plans are prepared on a case-
by-case basis to reflect the failed mitigation characteristics.
" "
Fieldbrook/#11-121
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March 13, 2014
Page 22
7.3 Contingency/maintenance activities will include, but are not limited to:
-Replacing all plants lost to vandalism, drought, or disease, as necessary.
-Replacing any plant species with a 20 percent or greater mortality rate with the same
species or similar species approved by the City Biologist.
-Irrigating the mitigation area only as necessary during dry weather if plants appear to be
too dry, with a minimal quantity of water.
-Reseeding wetland and buffer areas with an approved grass mixture as necessary if
erosion/sedimentation occurs.
-Removing all trash or undesirable debris from the wetland and buffer areas as necessary.
If you have any questions regarding this report, please call us at (253) 859-0515 or at
esewall@sewallwc.com .
Sincerely,
Sewall Wetland Consulting, Inc.
Ed Sewall
Senior Wetlands Ecologist PWS #212
Vanessa Dolbee
From:
Sent:
Kathleen Reader <kathleen@bradtree.com>
Tuesday, March 11, 2014 1 :34 PM
To: Vanessa Dolbee; Justin Lagers
Subject: Fieldbrook -interior parking-shrub calculation
Hi Vanessa,
Thank you for your call today. I went into the CAD drawing for Fieldbrook and extracted the calculations as requested.
They are as follows:
1590sf of interior parking landscape area is required
1 shrub per 20sf of landscape area= 79.5 shrubs (no more then 50% deciduous)
Quantities provided on plan:
Evergreen Shrubs: 290
Deciduous Shrubs: 61
The landscape plan and drawn meets the intent of this code section.
Please let me know if there is anything you need to complete your approval of this project.
Kind regards,
Kathleen
Kathleen Bradley Reader RLA, ASlA
Principal
BDG
Bradley Design Group, Inc.
Landscape Architecture+ Site Planning
o. 253.272.4848
,. 253.27&.0 132
www.bradtree.com
1
May 6, 2013
Revised February 26, 2014
ES-2089.02
Earth Solutions NW LLC
Avana Trails, LLC
c/o American Classic Homes
9725 Southeast 36th Street, Suite 214
Mercer Island, Washington 98040
Attention: Mr. Justin Lagers
Subject: Revised Coal Mine Hazard Traffic Loading Assessment
Proposed Fieldbrook Residential Plat
Southeast 172nd Street
Renton, Washington
LUA13-001109 FPUD
Reference: Final Planned Urban Development Report & Decision
Dated February 21, 2014
Earth Solutions NW, LLC
Plan Review Letter
ES-2089.02, dated May 6, 2014
Earth Solutions NW, LLC
Geotechnical Engineering Study
ES-2089, dated December 13, 2011
Dear Mr. Lagers:
• Gcotechnical Engineering
• Construction Monitoring
' Environmental Sciences
City of Renton
Plannir iq Division
In accordance with your request, Earth Solutions NW, LLC (ESNW) has prepared this revised
letter providing additional pavement loading and recommendations for the subject project as it
relates to the existing coal mine hazard and buffer area. We understand as part of the
referenced final conditional approval (item #18), further analysis that pavement designs near
the proposed trash collection area can withstand heavy traffic loading from commercial and
emergency vehicles. We understand the trash enclosure area has been relocated out of the
Coal Mine Hazard buffer area.
1805 -136th Place N.E., Suite 201 • Bellevue, WA 98005 • (425) 449-4704 • FAX (4251449-4711
Avana Trails, LLC
c/o American Classic Homes
May 6, 2013
Revised February 26, 2014
ES-2089.02
Page 2
In our opinion, the following pavement section recommendations will provide adequate support
for occasional HS-20 traffic loading associated with trash collection and loading from
commercial/emergency vehicles including, but not limited to, parking of fully-loaded emergency
vehicles. The design recommendations were evaluated using a maximum gross vehicle weight
of 50,000 pounds and outrigger pressure of 75 pounds per square inch (psi) for emergency
vehicles. This section is also provided in the referenced geotechnical engineering study which
requires the subgrade be proof-rolled using a loaded dump truck, which would mimic the weight
imposed by loaded trash and emergency vehicle loads. In our opinion, the occasional heavy
traffic loading and parking is considered transient and is not likely to cause subsidence within
the existing coal mine hazard area. "The proposed parking/trash facility would be an
appropriate use located within the hazard area".
Heavy Pavements
The performance of site pavements is largely related to the condition of the underlying
subgrade. To provide adequate pavement performance, the subgrade should be in a firm and
unyielding condition when subjected to proofrolling with a loaded three-axle (100,000 pound
gross vehicle weight) dump truck. Structural fill in pavement areas should be compacted as
recommended in the "Site Preparation and Earthwork" section of the referenced geotechnical
engineering study. It is possible that soft, wet, or otherwise unsuitable subgrade areas may still
exist after base grading activities. Areas of unsuitable or yielding subgrade conditions will
require remedial measures such as overexcavation, placement of a geotextile and thicker
crushed rock or structural fill sections prior to pavement.
For relatively high volume, heavily loaded pavements subjected to moderate to high, loaded
truck traffic, the following preliminary pavement sections can be considered:
• Three inches of hot-mix asphalt (HMA) placed over six inches of crushed rock base
(CRB), or;
• Three inches of HMA placed over four and one half inches of asphalt treated base
(ATB).
The HMA, ATB and CRB materials should conform to WSDOT specifications. All soil base
material should be compacted to at least 95 percent of the maximum dry density.
Avana Trails, LLC
c/o American Classic Homes
May 6, 2013
Revised February 26, 2014
ES-2089.02
Page 3
We trust this letter meets your current needs. If you have any questions, or if additional
information is required, please call.
Sincerely,
EARTH SOLUTIONS NW, LLC
Kyle R. Campbell, P.E.
Principal
Earth Solutions WI, LLC
February 26 1
\ 2014
Vanessa Dolbee
Senior Planner
City of Renton
1055 South Grady Way
Renton, WA 98057
RE: Fieldbrook Commons Final PUD, LUA13-0011009, FPUD
Mrs. Dolbee,
Please find enclosed the following (re)submittal items as required in your Administrative Final PUD
report & Decision dated February 21, 2014:
• 2 copies of the updated Site Plan
• 3 copies of the Landscape Plan
• 3 Copies of the Tree Retention Plan
• 3 Copies of the Irrigation Plan
• 3 Copies of the Final Wetland Mitigation Plan
• 3 Copies of the Final Wetland Mitigation Report
• 2 Copies of the proposed Wetland and Coal Mine Kiosk
• 2 Copies of the Geotech letter
Please let me know if you require any additional information.
m Lagers
Director of Land Acquisition & Development
Avana Trails, LLC
Business Office
9675 SE 36" Street, Suite 105
Mercer ls/and, WA 98040
P: (206) 588-1147 F: (206) 588-0954
Tree Retention Legend
NOTE:
CRITIAL N>.EA TREES
ElC"1'llfOCR!TICAI.ARU.Til!!E:STOl>:EMAJN
{P OE.o.D.-•o.""""'OA:tw,t()EAC)IJSTI>E.SLOCI.TW
INCRmcAll'PU.S
nt!'ES IN EXl5"'1~G CRfflc.t,LAAE,1,S TO BO REMO'VEDOR
NT!i:"1W.l.Y EFFE<:lE<l RV .... n..oJ<p CR .. TIOHACrnmY
f'-.... --"'-"'"')
DEVELOPABLE AREA TREES
PSAI), D .. EASH>. D'l'1NP OIi °""""ROUS TIIEE9 -TO BE "'-
EXISTING VLW.E'n'llce.!ITOBE~[hl<Mll.c.OC,o,n,pQN
Del'ELO<>,..LS PORT1C« OF Sil
EJClllTI>,t: VLW.ETMES,N~OWTOOE~[hl<Mll -LOCA1'0<>
DEVELOP,.,.LS "°"1iOHOF SITF
EJ(l5TIN<l "1"8lC Tl<EE$ TO !1£ ...... l~A'1EI, COO<OTI<UCITON
2061 -TRtt •lf«R
POINTS-· "'2J.~ --Till'l,El.EVATIO'I
20.l~M -TREECAl.rPE~&-°"'a =es . .,...._ __
=·--·-·-uca.US'TVl·-Tlllnl<---
TREES LOCATED IN THE THREE WETLAHDS TO BE FILLED ( 'D',
'E' AND F') W£RE NOT CALCULATED AS "CRITTCAL AREA9"
TREES. TREES WERE CALCULATED AS VIABLE OR DEAD,
DISEASED, DYING OR DANGEROUS -SEE PLAN FOR TREE
DESIGNATIONS.
Tree Retention Calculations
1 Tot,,I Nu-of r.-•nd Condition -,,. on Pn,Jacl 1111:a --119po,t
(GrM-Inc, -S.pt. 8. 2011) • 7MTotal T,_
2a. Dadudlona fur Emstlng y,-In o.-lopablo "'*" of lllo:
Daad, 0--, I)__.,,... or DJlng • 151
l.ocnod In Pf'O_.,cl ROW• 18
TOTAL• 1et
2b.lncrttlCIIII...,_:
Ylabla T,-In Cr1tlclll -ta Ramllln • 1U
T'"'!Mt.,."boo-po•WllllandC...t11111-•h-,,onplan-
DR81t'Ong V-RCoo ll9qunt (bu! ... not~ In -
calculatlo,.. • !Ul
n..d, D-, D.,.llffl)tla orDJlng T,_ proWellandC.-.., • ~
t-~ r--Raml>YKI rarw....,... er..tlon • 41 T<>lal DOO r--lnlng)
TOTAl-•1!5l
T-1 NumbwofE>colude<IT-•321
3. Su_ II.,. t from 11.,.1 • "9ll Vllbloo T,_"" g,m
4.--calculallon:
.1 ~4'15•oM.5VlabllT-Raqu-lDba-lrwd
!I. Nu.,berolE>ll""9Vlabl•T-.i.,b,oRm,lno,d•olO
s. r .... to 11a R.placo,d • 1
1.C.HparlnohuRo,q,,lrM•M"
I. Numt,,or o1 2" Rtpla .. ,,_lT,-it.qolrod •42
Concl.,.ion
0Yerl1D0)2"C,.llpar-•,..,...l»Mdkrthioptojl,ct•lta•--.~
1o1-., Kmntpbonll"!l•ond-n•--· Thia-II--~ -I• prupon,cl In _ __,d....,..
,II
EXISTING TREE TO BE I
,,.......--------=-.---"'/ DRIP LINE OF EXJSTING I
~
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Sewall Wetland Consultin Inc.
PNW HOLDINGS LLC -FIELDBROOK COMMONS
CITY OF RENTON
Sewall Wetland Consuhing, Inc.
27641 Covington Way SE, #2
Covington, WA 98042
MITIGATION PLAN 2-24-2014
NWS-2012-1281
Prepared For:
PNW Holdings, LLC
9675 SE 36 1h Street
Snite 105
Mercer Island, Washington 98040
Attn: Justin Lagers
February 24, 2014
Job#ll-21
City of Renton
PJannin~:-1 Division
FEB 2 6 10i4
Phone: 253-859-0515
Fax: 253-852-4732
Sewall Wetland Consulting, Inc.
27611 Covingtm Way SE #2
Covington WA sro!2
PNW HOLDINGS LLC -FIELD BROOK COMMONS
CITY OF RENTON
1.0 INTRODUCTION
MITIGATION PLAN 2-24-2014
NWS-2012-1281
Phare: :filS59.IB15
Fax: 253-S52-4732
This report describes the proposed wetland mitigation for the Fieldbrook Commons PUD
project, located on the east side of Benson Road South, and north of Cedar A venue South
(SE l 72"d Street) in the City of Renton, Washington (the "site").
2.0 PROPOSED PROJECT & MITIGATION SEQUENCING
The purpose of the proposed project is to construct a multi-family apartment complex as
the property has been zoned for, as well as planned for in the City of Renton
Comprehensive plan. The need for apartment units within Renton is high and this project
has been proposed to meet that need.
The proposed project is the construction of a 161 PUD project with associated
infrastructure. The location of Wetlands D, E and F result in most of the developable
property on the site being encumbered by wetland or buffer. Since these wetlands,
particularly Wetlands E and Fare of low value, and Wetland Dis small in size but
because of its linear shape impacts the sites usable space so greatly, we are proposing
filling these three wetlands.
As a result, it is our intention to fill these wetlands and provide adequate mitigation for
their lost functions by creating wetland on the eastern side of the site in and around
Wetlands A, Band C. Impacts to wetlands must be justified through a mitigation
sequence as detailed in City of Renton Code. Ideally we would be able to use the King
County fee mitigation banking process as is preferred by the Corps and W ADOE. We
are in agreement that using the fee-in-lieu mitigation option would be ideal and the
easiest/fastest way to mitigate the proposed impacts. However, the City of Renton has
refused to let us use this as a mitigation option as it moves the mitigation area outside the
City limits and in their opinion is a net loss of critical areas to the City. It appears the
City looks at the mitigation, and ttail through the buffer as part of the "public benefit"
aspect of this project. The construction of the mitigation onsite, as well as the placement
of a trail through the buffer are being required by the City to allow us to construct this
Fieldbrookl# 11-121
SewalJ Wetland Consulting, Inc,
February 24, 2014
Page 2
project. It is our opinion that the trail does increase the amount of human intrusion into
the wetland, and would be best left off the plan. However, the City of Renton will not
accept this and are forcing us to bring a trail through the buffer regardless of the logic.
The next best option is on-site replacement of the wetland area and functions as proposed
in our mitigation plan.
The attached mitigation plan has been prepared with the recommended documents
elements as requested by Suzanne Anderson of the US Army Corps of Engineers in
previous comments. This plan is prepared in the exact same manner and with the same
information as numerous mitigation plans we have submitted and had approved by the
Corps for various Nationwide as well as Individual Permits. As requested the monitoring
has been modified to include I Oyears of monitoring.
(c) Per the Federal Mitigation Rule, you must provide additional information to
document that a watershed approach to compensatory mitigation was used for the mitigation plan
(33 CFR 332.3(c)]. A link to Wetland Mitigation Situ Using a Watershed Approach, F.cology
Publication #09-06-032 is available fiom our webpage at www.nws.usace.anny.mil, select
"Reau)atory Branch, Permit Information", then "Mitigation Resources", then "Mitigation Tools".
We ffl:ODllDelld that you demonstrate that the chosen mitigation site satisfies criteria in Charts 2
and 3 of the site selection guidance (i.e., identified as a site with potential and that is
IIUIBimble); and that it satisfies criteria in Charts ,4 throup 11 for the appropriate functions.
Using Chart 2 from the Watershed approach which is an analysis utilized to pick a
mitigation site is not really applicable, as the City of Renton is requiring we conduct the
mitigation on the site where the impact is occurring. In addition, there is no other
available mitigation sites within this drainage basin that is owned by either the City or the
client for use as a mitigation receiving site. Therefore, mitigating on-site is the only
feasible alternative given these constraints.
In regards to Chart 3;
Question 3A: Identify the watershed processes that have been altered within the hydrologic
unit where the mitigation site is located.
Human activities can change watershed processes by changing water flows; introducing
nutrients, pollutants, non-native species. and sediment; and by fragmenting habitats.
Changes in these processes often create problems that can be improved through mitigation
activities. To begin you need to identify the major landscape-scale problems (i.e., alterations
to processes, not structure) that exist in the hydrologic unit where your site is found This will
help you identify which restoration or enhancement actions will be the most effective in that
hydrologic unit. Check the appropriate column in the following table to identify problems
that might exist. The last column notes if the altered process has already been identified in an
existing watershed plan as a problem that needs to be addressed
Fieldbrook/#11-121
Sewall Wetland Consulting, Inc.
February 24, 2014
Page 3
The current flooding events within the Soos Creek drainage are generally not increasing due
to the current use of modem storm water facilities within the basin. However, there still is
some increase as there is more water getting to the basin faster in storm events.
There is less eutrophication in rivers and streams in the basin primarily from removals of
livestock and old septic systems.
Water quality has been reduced in the basin to a degree.
Some stream and bank erosion does occur within the basin.
Habitat has become more fragmented as the area's population grows and more development
occurs.
Question 3B: Will the mitigation result in a wetland of the appropriate hydrogeomorphic
(HGM) class for the landscape setting?
Wetland mitigation sites are sustainable only if the type of wetland being proposed is
appropriate for its position in the landscape. The HGM classification of wetlands is based on
characteristics of water movement and position in a landscape. Therefore, it can be used to
identify appropriate wetland types for different locations in a hydrologic unit.
Yes, we will be mitigating for depressional wetlands with a depressional wetland
mitigation area.
Question 3C: Will the primary source of water to the mitigation site be appropriate for the
HGMclass?
Groundwater and direct precipitation will be the source of hydrology for the wetland
mitigation site as was the source for the impacted wetlands. Hydrologic monitoring of the
mitigation site has shown that surficial groundwater elevations in the mitigation area will
sufficiently hydrate the creation area with soils saturated to the surface and some standing
water in the growing season.
Question 3D: Will the site have an adequate supply of water to maintain a wetland without
engineering the delivery of water that would require long term control or maintenance?
The surficial groundwater monitoring and proposed grades should create a wetland area that
will require no additional or artificial source of water to maintain its viability. It is thought
that Wetland A which is located within the area of an old mine is discharging water from
historic mining and as such there is an abundant supply of water in this area.
Question 3E: Will the mitigation activities maintain hydric soils, if they exist, at the site?
Removing hydric soils can decrease the potential for success of wetland restoration. Hydric
soils often contain a seedbank of wetland plants that supplement any planting you may
propose.
Fieldbrook/#11-121
Sewall Wetland Consulting, Inc.
February 24, 2014
Page 4
Hydric soils from the filled wetlands will be mixed with topsoil and utilized in the newly
created wetland maintaining viable seedbanks.
Question 3F: Can the mitigation be designed to control aggressive plant species?
There is currently not a predominance of aggressive invasive or weedy species in the area
of the proposed mitigation or the two wetlands that will be connected together with the
creation. Standard invasive species control will be utilized in the mitigation area which
has proven successful in other mitigation sites.
Regarding the appropriate Charts 4-11;
Chnl't 5-: Goal~ Impro,iug Hydrology Functions in Depressional Systems Outside of floodplains
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Fieldbrook/# 11-121
Sewall Wetland Consulting, Inc.
February 24, 2014
Page 5
Chart i: Gval -Imprm:ing \Yater Quality (WQ) Funrtiom in Depres5ion;,l S.y~te1m Outa;ide of floodplain<..
can .. 11111n1.._ildll.. 1-
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This sequencing requires addressing the following criteria;
a. Avoid any disturbances to the wetland or buffer;
Fieldbrook/# 11-121
Sewall Wetland Consulting, Inc.
February 24, 2014
Page 6
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The site contains three small wetlands which the developer proposes to fill and mitigate
for through the creation of a new wetland area and enhanced buffer areas for the existing
and remaining wetlands A, B & C in the eastern third of the site. Wetland F located on
the western side of the site is Category III wetland measuring I 595sf. Due to the
requirement to provide a secondary fire access directly out to I 08'h Ave S.E. the
developer is unable to avoid direct impact to this wetland. Wetland E, located in the
center of the site and adjacent to S.E. 172nd St. measures 68sf and is rated as a Category
IV wetland. Due to the requirement to dedicate and construct the other half of the S.E.
172nd St. ROW the developer is unable to avoid direct impacts to this wetland. Wetland D
is located generally in the center of the project and is rated as a Category III wetland
measuring 767lsf.
b. Minimize any wetland or buffer impacts;
The developer previously attempted to plan roadways and improvements around Wetland
D, however the location and shape of the wetland impacted the vehicular circulation and
Fieldbrook/# I I -I 2 I
Sewall Wetland Consulting, Inc.
February 24, 20 I 4
Page 7
building locations to such an extent that the project would not be financially feasible to
construct.
c. Restore any wetlands or buffer impacted or lost temporarily; and
Restoration of Wetland Din this location would not be feasible due to the location of the
impacts and configuartion of the parcel and remaining wetland.
d. Compensate for any permanent wetland or buffer impacts by one of the following
methods:
i. Restoring a former wetland and provide buffers at a site once exhibiting
wetland characteristics to compensate for wetlands lost;
This is not applicable to this site as no historic wetlands are located on the property.
ii. Creating new wetlands and buffers for those lost; and
A total of9,334sfofwetland will be filled.
US Army Corps of Engineers Required Mitigation
Using the recommended ratios from Table 1 a, of the W ADOE Publication Wetland
Mitigation in Washington Stale Part I, (WADOE March 2006 Pub. #06-06-01 Ja)
Table 1
Wetland Size Category Vegetation Ratio Required
Type Wetland
Creation
D 7671sf III Forested 2:1 15342sf
E 68sf IV scrub-shrub 1.5:1 102sf
F 1595sf III scrub-shrub 2:1 3190sf
Total 9,334sf 18,634sf
As described above, based upon the required USA COE and W ADOE ratio, a total of
J 8,634sf of wetland is required to be created.
•
Fieldbrook/# 11-121
Sewall Wetland Consulting, Inc.
February 24, 2014
Page 8
The proposed mitigation will create 25,430sf of wetland, which exceeds the required
USACOE ratios by 6,796sf. The extra wetland being created over the WADOE
recommended ratios is a result of the City of Renton having a higher mitigation ratio
requirement than the Corps.
As seen in Table 2 below, using the three main functions from the W ADOE Rating
System recognized by the Corps, a substantial functional lift will be attained from the
connection of Wetlands A and C with 25,430sf of additional wetland over the existing
functions of the proposed fill wetlands.
Table 2. Functional Comoarison of imoact wetlands and orooosed miti ation
Wetland Area Flood Species Water Hydrologic Habitat
Storage Richness Qual. Function Function
caoacitv Function
Category
WetlandD 767lsf 3800cuft 5 snecies l2vts 8vts 13vts III
Wetland£ 68sf 34cufi 2 snecies llvts 4vts IOvts IV
Wetland F l595sf 500cufi 5 svecies 20vts 8vts llvts III
Pronosed 25430sf 7600cuft 15 soecies 24ots 20ots 2Iots II
Functional +16096sf +3266cuft +Sspecies* +9pts +12pts avg +9pts +l
I Lir, av11: av11: Cate11:orv
*only 7 different species were found (excluding exotic/invasives) in Wetlands D, E &F
The newly created wetland will connect to existing Category III wetlands (Wetlands A
and C) and provide enough lift that this wetland will now be considered a Category II
wetland under the WADOE rating system. This is a substantial lift in function, surface
water storage and species richness over the fill of Wetlands D, E & F, which are
generally low value Category III and JV wetlands.
Hvdrologic monitoring of mitigation sile and general construction overview
To compensate for the impact to 9,334sf of Category III & IV wetland, we will create
25,430sfofwetland between Wetlands A and C. This results in an overall wetland
mitigation ratio of 2.72:1 (created wetland:impacted wetland). This mitigation will
create Category II wetland for a combination of Category Ill and IV wetland impacts. As
depicted on the attached Final Mitigation Plan, 25,430sf of area will be excavated out to a
similar depth to the existing wetland in two areas to intercept the surficial groundwater
table and create conditions favorable to create wetland hydrology.
A series of 6 monitoring pits/wells were located within the proposed wetland mitigation
area. These were monitored with weekly site visits from April of 2012-August 2012 as
well as March and early April of 2013. At each of these points soil saturation and water
table levels were measured to determine what surficial groundwater elevations are, to
facilitate designing grades for the new wetland creation area. What we found was that
within the proposed creation area, groundwater levels in the early growing season area
Fieldbrook/#11-121
Sewall Wetland Consulting, Inc.
February 24, 2014
Page 9
between 14" -30" below the existing surface (see table below). It is assumed in the very
early growing season (February and March) the groundwater elevations are shallower
than the measurements we took, meaning the groundwater elevations are closer to the soil
surface.
As shown on the attached Final Mitigation Plan Sheets W l-W3, we utilized these
existing groundwater contours to create the new grades for our mitigation site. As can be
seen by the grades and associated cross-sections, the grades will remove soil down to the
existing groundwater elevations to create wetland areas with soils saturated to the surface
for the early growing seasons, to also include flat areas that will hold some shallow I" -3"
of surface water to provide a variety of wetland hydro logic regimes from saturated, to
seasonally flooded. The fact that the excavation is being brought to the higher levels of
groundwater within the growing season, and will not cut into the surficial groundwater
table, should alleviate the concern of intercepting and draining off this water. All we are
doing is removing the surface soil above the existing sloping groundwater table to make
those saturated soils closer to the surface. Soil disturbance of the groundwater retaining
portion of the soil column will not occur.
Although creation of a slope type wetland is not the most conventional or common
mitigation method, it is a feasible method of wetland creation when conditions warrant its
use. Our company has been involved in two larger wetland creations using this type of
concept, most recently a 3 acre wetland creation with over IO' of vertical drop across the
landscape in sloping of the creation area (see Snohomish County Parks Centennial Trail
II mitigation plan reviewed and approved by Jonathan Smith of the Corps). By using the
same method of removing soil down to the level of the highest groundwater elevations as
is proposed in the Fieldbrook project, we successfully created a 3 acre sloping wetland in
the previously described project.
Table 3. Groundwater elevations below surface o hvdrolo• v monitorin21JOints 2012
Monitor DATE
point&
elev.
4113 4127 5111 5124 617 6128 7112
A417.5' -15 -14 -15 -20 -26 drv drv
B418' -17 -16 -16 -22 -27 dry dry
C417' -20 -18 -17 -20 -25 dry drv
D416.5' -14 -14 -14 -16 -20 drv dry
E4 l 8.5' -27 -26 -24 -30 -36 drv drv
F418' -21 -22 -20 -28 -36 drv drv
Note: All elevations indicate the elevation of the saturated capillary fringe of soil
saturation observed in hydrology monitoring points.
8112
drv
drv
drv
dry
drv
drv
Fieldbrook/# 11-121
Sewall Wetland Consulting, Inc.
February 24, 2014
Page 10
Table 4. Groundwater elevations below surface o 'hvdrolo1 v monitorinl! points 2013
Monitor DATE
point&
elev.
3/15 3/29 4/9
A417.5' -12 -I 0 -15
B418' -15 -15 -14
C417' -17 -16 -18
D416.5' -IO -11 -13
E418.5' -23 -20 -23
F418' -18 -19 -20
Note: All elevations indicate the elevation of the saturated capillary fringe of soil
saturation observed in hydrology monitoring points.
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Fieldbrook/#11-121
Sewall Wetland Consulting, Inc.
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February 24, 2014
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A small berm will be placed between the wetland creation area and Wetland B. This will
prevent (in the unlikely case of surface water overtopping the edge of the wetland) the
wetland creation area between Wetlands A and C from draining into Wetland B.
Hydrologic monitoring will be conducted using peizometers in the proposed mitigation
area through the winter and spring to verify groundwater elevations. This area will then
be graded back at a slope no steeper than 3: I (horizontal :vertical). The area will then be
planted with a mix of native trees, shrubs and herbaceous species and will also include
several habitat features (logs and snags) to increase its habitat function.
As depicted on the attached Fieldbrook Commons Mitigation & Grading Plan ( dated 9-
23-13), a split rail fence will be placed at the edge of the wetland buffer. There are no
living spaces or recreational space next to the wetland or its buffer limiting use of this
area. However, the City of Renton is requiring that the applicant provide a trail through
the wetland buffer as depicted on the plan. We have moved this trail to the north,
splitting the buffer area between the wetland creation area and Wetland B to the north to
maximize distance of the trail from the wetland as best possible.
Signage and a split rail fence along the trail indicates the character of the critical area and
will discourage intrusion into the wetland or buffer.
All lighting will be located outside the wetland and buffer. All lighting in the developed
portion of the site will be directed away from the wetland and its associated buffer.
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The goal will be to create at least 25,430sf of area meeting all three wetland criteria
(hydric soils, hydrophytic vegetation, and wetland hydrology) as specified in the
Washington State Wetlands Identification Manual (W ADOE, March 1997) and the
Western Mountain.v, Valleys and Coast region Supplement (Version 2.0) dated June 24,
2010. All disturbed buffer areas will be restored with a dense planting of native trees and
shrubs. The resulting wetland creation area will be monitored for 10 years. The creation
area will be delineated at Years 5 and IO to determine if 25,430sf of area meeting
wetland criteria has been created. If there is not at least 25,430sf of wetland created, the
shortage will be made up with either;
I. Fixing any small grading or hydrology issue which may be impacting the overall
size of the creation area, or;
2. Purchase of mitigation credits from the King County Fee program or other similar
program at that time.
Site Protection Instrument
The entire mitigation site as well as the buffer and undisturbed wetlands will be placed
within a Native Growth Protection Easement (N GPE) and recorded on title prior to
occupancy of the project.
Long Term Maintenance
The mitigation area will be monitored and maintained over the IO year monitoring
period. This will include trash removal, weed and invasive species removal, repair of
fencing and signage. After the required 10 years maintenance and monitoring period, the
facility operating manual will include a description of the NGPE are and what type of
maintenance can and should occur within this area. Management of the facility will be
responsible for this work following the IO year monitoring and maintenance period.
PROPOSED MITIGATION
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1.0 MITIGATION PROJECT OVERVIEW
February 24, 2014
Page 13
To compensate for the fill of a 9,334sf Category III & IV wetlands, it is proposed to
create 25,430sf of wetland between Wetlands A and C. Wetlands to be filled include
Wetland D (7,67lsfCategory III wetland), Wetland E (68sfCategory IV wetland) &
Wetland F (l,595sfcategory III wetland).
2.0 MITIGATION GOALS
2.1 Mitigation Goals
The mitigation proposal is to connect Wetlands A and C with an area of25,430sf of
wetland. The wetland creation areas will be densely planted with native vegetation. The
use of diverse native plantings are expected to significantly improve the overall function
of the wetland and buffer as it will remove dense thickets of exotic blackberry as well as
add emergent and shrub plant communities into what is now, a single class forested
wetland.
2. 2 Mitigation Goals
2.2.1 Create 25,430sf of emergent, scrub shrub and forested wetland.
3.0 CONSTRUCTION SEQUENCE
The construction sequence of this project will be implemented as follows:
3.1 Pre-construction meeting
3.2 Construction staking
3.3 Construction fencing and erosion control
3 .4 Clearing and grading
3.5 Stabilization of mitigation area
3 .6 Plant material installation
3. 7 Construction inspection
3.8 Agency approval
3.9 10 year Monitoring inspection and reporting
3.10 Silt fence removal
3.11 Project completion
3.1 Pre-construction Meeting
A pre-construction meeting will be held on-site prior to commencement of construction,
to include the biologist, the City, and the contractor. The approved plans and
specifications will be reviewed to ensure that all parties involved understand the intent of
the construction documents, specifications, site environmental constraints, sequences, and
inspection requirements.
3.2 Construction Staking
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The limits of clearing and grading near the critical areas will be marked in the field by a
licensed professional land surveyor prior to commencement of construction activities.
3.3 Construction Fencing & Erosion Control
All erosion control measures adjacent to the critical areas, including silt fencing and
orange construction fencing, will be installed. Erosion control fencing will remain
around the mitigation area until clearing, grading and mulch placement are complete in
upland areas outside the critical areas.
3.4 Clearing & Grading
Clearing and grading in and near the existing sensitive area will be per the approved Final
Mitigation Plans.
3. 5 Stabilization of Mitigation Area
All graded areas in the wetland or buffer will be stabilized with mulch upon completion
of grading. Orange construction fencing and erosion control fences will be restored (if
necessary) and placed around the critical areas.
3.6 Plant Material Installation
All plant material will be planted by hand per detail and Construction and Planting Notes.
The Mitigation Plan specifies the required size, species, quantity, and location of plant
materials to be installed. The contractor will mulch areas disturbed during the planting
process. Upon completion of the planting, the erosion control fencing will be restored
and repaired. Plant substitutions or modifications to locations shall be approved in
writing by the Owner's biologist prior to installation.
3. 7 Construction Inspection
Upon completion of installation, the biologist will conduct an inspection to confirm
proper implementation of the Mitigation Plan. Any corrections, substitutions or missing
items will be identified in a "punch list" for the landscape contractor. Items of particular
importance will be soils in pits, pit size, plant species, plant size, mulch around pits, and
tree staking.
Upon completion of planting, if installation or materials vary significantly from the
Mitigation Plan, the contractor will submit a reproducible "as-built" drawing to the
Owner. The As-built and installation sign-off report will be submitted to the Corps at
that time.
3. 8 Agency Approval
Following acceptance of the installation by the City, the City biologist should prepare a
letter granting approval of the installation.
3.9 Monitoring
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The site will be monitored for 10 years to insure the success of the mitigation project. If
additional years of monitoring are required by the Corps, the plan will be revised to
reflect this change. Any areas of temporary impacts that require restoration will be also
monitored for the full 10 year monitoring period.
3.10 Silt Fence Removal
Erosion control fencing adjacent to the mitigation area will remain in place for at least
one year, and/or until all areas adjacent to the mitigation area have been stabilized. The
City's Biologist may recommend that the fencing remain in place for a longer duration.
4.0 CONSTRUCTION AND PLANTING NOTES
4.1 Site Preparation & Grading
4.1.1 The Landscape Contractor will approve existing conditions of subgrade prior to
initiation of any mitigation installation work.
The Landscape Contractor will inform the Owner of any discrepancies between the
approved construction document and existing conditions.
4.1.2 The General Contractor will flag the limits of clearing with orange construction
fencing and will observe these limits during construction. No natural features or
vegetation will be disturbed beyond the designated "limits of clearing".
4.1.3 The Landscape Contractor will hand grub all non-native invasive plant species
including the removal of root crowns. These species may include, but are not limited to
Himalayan blackberry, evergreen blackberry, English ivy, and English holly. Weed
debris will be disposed of off-site.
4.1.4 The wetland area will be excavated to the depths shown on the Final Mitigation
Grading Plan and brought to final grade with 8" of topsoil. The biologist will be on-site
to confirrn the grading is acceptable for planting. A total of 4"-6" of compost will be
incorporated into the upper 12" of all graded areas in the wetland creation area.
4.2 Plant Materials
4.2.1 All plant materials will be as specified in the plant schedule. Only vigorous
plants free of defects, diseases and infestation are acceptable for installation.
4.2.2 All plant materials will conforrn to the standards and size requirements of ANSI
Z60. l "American Standard for Nursery Stock". All plant materials will be native to the
northwest, and preferably the Puget Sound Region. Plant materials will be propagated
from native stock; no cultivars or horticultural varieties will be allowed. All plant
materials will be grown from nursery stock unless otherwise approved.
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4.2.3 No balled and burlapped, or bare root plantings will be used. Only container
stock to be used.
4.2.4 All plant materials stored on-site longer than two (2) weeks will be organized in
rows and maintained by the contractor at no additional cost to the owner. Plant materials
temporarily stored will be subject to inspection and approval prior to installation.
4.2.5 Substitution requests must be submitted in writing to the Owner and approved by
the Owner's biologist in writing prior to delivery to site.
4.2.6 All plant materials will be dug, packed, transported and handled with care to
ensure protection from injury. All plant materials to be stored on site more than 24 hours
will be heeled into topsoil or sawdust. Precautionary measures shall be taken to ensure
plant materials do not dry out before planting. Wetland plants will be shaded and
saturated until time of installation. Immediately after installation the mitigation planting
area will be saturated to avoid capillary stress.
4.2.7 The contractor will verify all plant materials, the quantities shown on the planting
plan, and the plant schedule. The quantity of plant materials shown on the plan takes
precedent over the quantity on the plant list.
4.3 Plant Installation
4.3. l All plant materials must be inspected prior to installation to verify conformance of
the materials with the plant schedule including size, quality and quantity. Any plant or
habitat materials deemed unsatisfactory will be rejected.
4.3.2 All plant materials delivered and accepted should be planted immediately as
depicted on the mitigation plan. Plant materials not planted within 24 hours will be
heeled-in. Plant materials stored under temporary conditions will be the sole
responsibility of the contractor. Plants will be protected at all times to prevent the root
ball from drying out before, during, or after planting.
4.3.3 All planting pits will be circular with vertical sides, and will be sized per detail on
the mitigation plan and filled with pit soils approved by the Owner's biologist. Planting
pits shall not be deeper than the root ball. If native soils are determined to be
unacceptable by the Owner's biologist, pit soils will be amended with Cedar Grove
mulch or equivalent.
4.3.4 No fertilizers will be used within the wetland. In buffer areas only, install
"Agriform", or equal plant fertilizer to all planting pits as specified by manufacturer.
Fertilizers are allowed only below grade in the planting pits in the buffer areas. No
sewage sludge fertilizer ("SteerCo" or "Growco") is allowed in the mitigation area.
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4.3.5 All containerized plant materials will be removed from their containers carefully
to prevent damage to the plant and its roots. Plants removed from their containers will be
planted immediately.
4.3.6 All plant materials will be placed as shown on the approved mitigation plan. If
the final installation varies from the approved mitigation plan, the contractor will provide
a reproducible mylar as-built of the installed conditions. All plant material will be
flagged by the contractor.
4.4 Planting Schedule and Warranty
4.4.1 A fall-winter installation schedule (October I st -March 15th) is preferred for
lower mortality rates of new plantings. If plant installation occurs during the spring or
summer (March 15th -Oct. 1st) a temporary irrigation system will be required, unless
the area can be sufficiently hand-watered.
4.4.2 All disturbed areas will be protected with an arborists mulch to a minimum depth
of six inches.
4.4.3 The installer will warrant all plant materials to remain healthy and alive for a
period of one year after final acceptance. The installer will replace all dead or unhealthy
plant materials per the approved plans and specifications.
4.5 Site Conditions
4.5.1 The installer will coordinate with the Owner and the Owner's biologist for
construction scheduling.
4.5.2 Landscape installation will begin after the City acceptance of grading and
construction. The Owner will notify the Owner's biologist of acceptance of final
grading.
4.5.3 Silt fences will be installed as shown on the approved mitigation grading plans.
The installer is responsible for repair and replacement of silt fences disturbed during
plant installation. No equipment or soils will be stored inside the silt fences.
4.5.4 After clearing and grading is complete in the mitigation area, exposed soils will
be seeded or mulched. Orange construction fence will be placed around the mitigation
area to prohibit equipment and personnel in the mitigation area.
4.5.5 Final grading will be based upon soil conditions found during excavation of the
mitigation area.
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4.5.6 All plant material will be planted with suitable soils per planting details. Soils
from planting holes will be spread and smoothed across the mitigation area.
5.0 MAINTENANCE PROGRAM
This maintenance program outlines the program, procedures and goals for mitigation of
the stream and buffer impacts at the mitigation site. This maintenance program will be
the responsibility of the project owner through the duration of its ownership of the
mitigation area, or throughout the duration of the monitoring period, whichever is longer.
The maintenance contractor will complete the work as outlined below.
5.1 Maintenance Work Scope
5.1.1 To accomplish the mitigation goals, normal landscaping methods must be
modified to include:
a.No mowing or trimming of ground cover or vegetation in the mitigation
area.
b. No placement of fertilizers in the mitigation area.
c. No placement of bark mulch or equivalent in the mitigation area,
except as noted in the planting details.
d. No placement of grass clippings, landscape debris, fill or ornamental
plant materials in the mitigation area.
5.1.2 Work to be included in each site visit:
a. Remove all litter including paper, plastic, bottles, construction
debris, yard debris, etc.
b. Remove all non-native and invasive species identified in Table 3-1 of
Sheet W-3 of the Final Mitigation Plan within the mitigation area. All debris is to be
removed from site and disposed in an approved landfill.
c. Repair silt and/or permanent fencing and signage as needed.
5.1.3 Work to be completed on an annual basis includes:
a. Areas containing non-native/invasive species identified in Table
3-1 of Sheet W-3 of the Final Mitigation Plan should be controlled by hand cutting and
removing the root crowns for species such as Himalayan blackberry. Following hand
removal, treating re-sprouting invasive/non-native species with a glyphosphate herbicide
such as Roundup or Rodeo by a licensed applicator can be utilized.
b. Replace dead or failed plant materials. Replacement plantings are to be
of same species, size and location as original plantings. Plantings are to be installed
during the dormant period.
5.2 Maintenance Schedule
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The Owner will conduct all items listed in the Maintenance Work Scope on an annual
basis. Additional work may be required per the Monitoring Report and as approved by
the Corps. Additional work may include removal of the grasses around each shrub and
tree, installation of wood chips at each shrub and tree base and erosion control protection.
5.3 Watering Requirements
5.3.1 Watering with a temporary irrigation system will be required during the first
spring and summer after the installation. The temporary irrigation system may be
removed after the first year providing the plantings are established and acclimated to on-
site conditions.
5.4 Close-out of Ten-Year Monitoring Program
Upon completion of the monitoring program and acceptance of the wetland mitigation by
the Corps, the maintenance of the project will be reduced to include removal oflitter and
debris, repair of perimeter fencing and signage, removal of noxious weeds and
undesirable vegetation, and repair of vandalized areas.
6.0 WETLAND AND BUFFER 10 YEAR MONITORING PROGRAM
6.1 Sampling Methodology
The created wetlands and their associated buffers will be monitored once per year over a
ten-year period, starting with the first year after the plants have been installed, and as
required by the Corps. Monitoring will be conducted using the techniques and
procedures described below to quantify the survival and relative health and growth of
plant material. A monitoring report submitted following each monitoring visit will
describe and quantify the status of the mitigation at that time. Vegetation monitoring will
be conducted in August or September during monitoring years. Year 1 monitoring will
occur at least one calendar year after installation sign-off.
6.1.1 Hydrology
Wetland hydrology will be monitored using seven (7) piezometers per USACOE
specifications. These will be located within the restoration area to be placed at the time
of the installation sign-off by the biologist. Surface water level or ground water
saturation depths will be measured at these stations to determine if wetland hydrology has
been successfully attained. As is noted in the Corps of Engineers Wetlands Delineation
Manual (Environmental Laboratory, 1987) and the Western Mountains, Valleys and
Coast region Supplement (Version 2.0) dated June 24, 2010, wetland hydrology is
defined as inundation or soil saturation (usually within 12" of the surface) during the
growing season. The growing season for this area is generally defined as the period
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between the middle of March and the middle of November. However, plant growth often
occurs earlier in the year and sound professional judgment will be needed to determine
when the growing season is taking place at the site. Hydrology will be monitored twice a
month from March I st through May 30th of each year.
Wetland hydrology will be considered successfully created if wetland hydrology is
observed inundating or saturating the soil within 12 inches of the surface during the
growing season
6.1.2 Vegetation
The vegetation monitoring consists of inspection of the planted material in late summer
or early fall (August-September) to determine the health and vigor of the installation, as
well as coverage estimates. All the planted material in the wetland and buffer will be
inspected during each monitoring visit to determine the level of survival of the
installation.
All plants will be inspected and recorded as to whether they are alive or dead based upon
the "as-built" in Years 1 & 2. In Years 3-5, coverage estimates will be used to determine
success of the vegetation component.
A total of 19 permanent 3.0m rectangular monitoring plots will be located within the
mitigation area as depicted on Sheet W-3 to monitor shrub and tree species coverages.
Within each of these 3.0m plots, the emergent plant community coverage of vegetation
will be measured with 0.25m rectangular plots. Estimates of coverage percentages will
be made within these plots.
Photographs of the mitigation area will be taken from 6 photo points to be located during
the installation sign off as well as at each permanent monitoring plot. Photographs will
be taken at each of the monitoring and included with the monitoring report for each year
from these points.
During years 1 & 2 of the monitoring, replacement plants as well as dead plants will be
flagged with distinctive flagging to distinguish what plants these are.
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6.2 STANDARDS OF SUCCESS
PERFORMANCE STANDARDS
ITtM YlAlS TO II MOM1'0lt& POfOIMANCI ITANDMI)
Wll\AND H'tDROlOGY 'VEAR$ 1, 2. !, 4, S. 7 .tiND 10 SOlLS WITHIN CREATED WETlAHD WAS SttAl..l.1£ SATUR.ATtDTOfflE SUUltl:f., HAvt SHALLOW
(CRtAflD WITlAND AND GAOUNDWATtll ftfl[S[NTWITH .. 12 INCHCS Of THC SOit Sllftf~E,~ HAV£ $UflFAf.£ JrONDING
WUl.ANO "J'WETI.NID q P'RlstNT roR Af UAST FOOR (4) CONSEClJJIVE Wt:EICS DURING THE SIASON WHEN RAINfALL 15
LISS THAN OR EQUAL TO THI MlAN FOR THE PII\IOO Of AVAN.Allf RECORD.
wrnAND D£UNEATl0N YEAII.S 5 i6.N010 PERFORM Df:UNEATION Of WETlAHO A. Wm.AND C, AND wtllAND CREATION Nl£A TO OlTEUl'INE IF
WHETHER Wm.AND A ANO Wm.AND CAM: -YKCTED flYTHE WETLAND otEA.TlON. PERFO'™ANCE
STANO.UO 15.s.t.TIYIED IF THERE IS NO CHANG£ TO WfllAND llMITS,
NATIV£ YEGUAflON Y'£MS 1, l, S, 4, S. 7 AND 10 TREE ~O SHU SPECIES
(atEA TED WETlANO/ (TO OCCUR IN AUGUST OIi . looi i.Hi\lNM. iv MT Al.LED PWfTSTOo: NTER THE RRST GltOWING SEASON .
ENHANCEOW£l\AHO llUFFEI) SEPTEM&n l!GINNNG ONf . '°" SIJRYfYAL IY INSTAllED Pl.ANT STOO: AFJEII. TltE S£CONOGROWING SEASON.
't't.U. JOUOWlNG lNITIAL . INHANCKl IUfflfll P'I.ANT1Nli AIIIIAS: MINIMUM PHlaNT COVER IY TUfS AND SHRIJ8S: Y1:AR 3:
rLANT INSTAUATION.) J091i; VEAi $; "'S"; 'tEAII. 7: 6S"; YEAR 10; ""6. IJf' TO 20" OF THE NATIV( WOOOY PlANT SPECIES
COVfRAGE MAY BE COMPRISED Of ~JtABlE NATM COlO..ZING 5'EOES. . CMAllOWITUNO Pl..f.NTIMMIAS; MIHIMUM N-«NT COYElt lY TM ES ANO SHRUIS: V£AA S: '°"; YEM S: SOM; Y!Alt 7: IIO!'; YlM 10: !111%. Uf' TO 2°" OF THE NATIVE WOOO'I' PLANTSPfOES
COV£MGE MAY If COMnlSlD Of D£SIM1lE NA TM COI..ONIZING 5'£0ES. . AFTEJI. THE RFTH GflOWING SEASON, A MINIMUM Of FOUi\ DIFFEtENT PlANT 5PECIES Will
COMPJISE GRfA.lEII; TKAN 1QKCOY'Ell;A6£.
[MEll6.NT Sl'ECIES
• 25 AviMGf. COVEAAGE IV INSTAU.ED PU.NT Sl00: AFTER THE RfCST 6ROWlrfG SEASON. . 80% AV£UGE. COYEMGE IY INS TAI.LEO PlAHT SlOO: AFUl lHE 5th 6: 7tk ~ MUOU.
• ~AVfll;AG£C0YlkAGtlVNATM IMIR61:NT PLANTS,IOESNTEA rtef TH NG SEASON . . AfffR THE FtHH GROWING SlASON, A MINIMUM Of THJI.IE OtfffRINT PLANT sPiCIIS WlU.
COMPfUSEGIIIATER THAN 1°"COVIRAGE,
1tn,U, l, S. .. , ).11•,JIIII .W
NA'fIV[ VtG!TATION
(fl!I «aJI Ill AU.ilutt ~ . 100% SUJlVIVAl lY IHSTAL1.ED PLANT STOCI( Af-THI ntE Fifi.ST GROWING SEASON . IIY'Ol:Mll,Pll:91Nl'Ki:,tlll 80% SURVIVAL IY INSTMl.10 P\ANT $TOO.: NTEJt THE Tfflfl.D GfWWIN<i 5iA50N. (RlSTORID WULANO IUFFH) "IIUf(l.~NO""'lllil .
HMl lfDIM.V..100
LfSS THAN tO!lo COY!IAGl IV Alt Cl.ASS "A". •r, AND MC" NOXIOU$ WUDS IINClUOING NOM-ltt:GUlATID
NOXIOUS WfEO S,£C16 Vf:ARS 1, 2. J, 4. !, 7. AND 10 "I" AND "C" NOXIOUS WilD5) K>fNTIFED ON THI LATUf KING COUNTY NOXIOUS WiiD UST. N0J00US
WHO CONTROl PERfOAMANCE ST ANDI.RDS AM. UMITIO TO Pl.ANTED AREAS ONLY.
7.0 CONTINGENCY PLAN
7.1 A contingency plan can be implemented if necessary. Contingency plans can
include re-grading, additional plant installation, erosion control, modifications to
hydrology, and plant substitutions including type, size, and location.
7 .2 Careful attention to maintenance is essential in ensuring that problems do not
arise. Should any of the site fail to meet the success criteria, a contingency plan will be
developed and implemented with the City approval. Such plans are prepared on a case-
by-case basis to reflect the failed mitigation characteristics.
7.3 Contingency/maintenance activities will include, but are not limited to:
-Replacing all plants lost to vandalism, drought, or disease, as necessary.
-Replacing any plant species with a 20 percent or greater mortality rate with the same
species or similar species approved by the City Biologist.
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-Irrigating the mitigation area only as necessary during dry weather if plants appear to be
too dry, with a minimal quantity of water.
-Reseeding wetland and buffer areas with an approved grass mixture as necessary if
erosion/sedimentation occurs.
-Removing all trash or undesirable debris from the wetland and buffer areas as necessary.
If you have any questions regarding this report, please call us at (253) 859-0515 or at
esewall@sewallwc.com .
Sincerely,
Sewall Wetland Consulting, Inc.
Ed Sewall
Senior Wetlands Ecologist PWS #212
Sewall Wetland Consultin Inc.
PNW HOLDINGS LLC -FIELD BROOK COMMONS
CITY OF RENTON
Sewall Wetland Consulting, Inc.
27641 Covington Way SE, #2
Covington, WA 98042
MITIGATION PLAN 2-24-2014
NWS-2012-1281
Prepared For:
PNW Holdings, LLC
9675 SE 36th Street
Suite 105
Mercer Island, Washington 98040
Attn: Justin Lagers
February 24, 2014
Job#ll-21
FEB 2 6 2014
Phone: 253-859-0515
Fax: 253-852-4732
Sewall Wetland Consulting, Inc.
27641 Covington Way SE #2
Covington WA ~
PNW HOLDINGS LLC -FIELD BROOK COMMONS
CITY OF RENTON
1.0 INTRODUCTION
MITIGATION PLAN 2-24-2014
NWS-2012-1281
Phore: 253-859-0515
Fax: 253-S52-4Z32
This report describes the proposed wetland mitigation for the Fieldbrook Commons PUD
project, located on the east side of Benson Road South, and north of Cedar Avenue South
(SE 172nd Street) in the City of Renton, Washington (the "site").
2.0 PROPOSED PROJECT & MITIGATION SEQUENCING
The purpose of the proposed project is to construct a multi-family apartment complex as
the property has been zoned for, as well as planned for in the City of Renton
Comprehensive plan. The need for apartment units within Renton is high and this project
has been proposed to meet that need.
The proposed project is the construction ofa 161 PUD project with associated
infrastructure. The location of Wetlands D, E and F result in most of the developable
property on the site being encumbered by wetland or buffer. Since these wetlands,
particularly Wetlands E and Fare of low value, and Wetland Dis small in size but
because of its linear shape impacts the sites usable space so greatly, we are proposing
filling these three wetlands.
As a result, it is our intention to fill these wetlands and provide adequate mitigation for
their lost functions by creating wetland on the eastern side of the site in and around
Wetlands A, Band C. Impacts to wetlands must be justified through a mitigation
sequence as detailed in City of Renton Code. Ideally we would be able to use the King
County fee mitigation banking process as is preferred by the Corps and W ADOE. We
are in agreement that using the fee-in-lieu mitigation option would be ideal and the
easiest/fastest way to mitigate the proposed impacts. However, the City of Renton has
refused to let us use this as a mitigation option as it moves the mitigation area outside the
City limits and in their opinion is a net loss of critical areas to the City. It appears the
City looks at the mitigation, and trail through the buffer as part of the "public benefit"
aspect of this project. The construction of the mitigation onsite, as well as the placement
of a trail through the buffer are being required by the City to allow us to construct this
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project. It is our opinion that the trail does increase the amount of human intrusion into
the wetland, and would be best left off the plan. However, the City of Renton will not
accept this and are forcing us to bring a trail through the buffer regardless of the logic.
The next best option is on-site replacement of the wetland area and functions as proposed
in our mitigation plan.
The attached mitigation plan has been prepared with the recommended documents
elements as requested by Suzanne Anderson of the US Army Corps of Engineers in
previous comments. This plan is prepared in the exact same manner and with the same
information as numerous mitigation plans we have submitted and had approved by the
Corps for various Nationwide as well as Individual Permits. As requested the monitoring
has been modified to include I Oyears of monitoring.
(c) Per the Fcdcral Mitigation Rule, you must provide additional information to
document that a Wlltel'llhcd approach to compensatory mitigation was used for the mitigation plan
[33 CFR 332.3(c)J. A linlt to Wtttland M/Jlgation Situ Using a Watttrsht!d Approach. Ecology
Publication #09-06-032 is available from our webpage at www.nws.usace.anny.mil, select
"Regulatory Branch, Permit Information", then "Mitiption R.csources", then "Mitigation Tools".
We recommend that you demonstrate that the chosen mitigation site satisfies criteria in Charts 2
and 3 of the site selection guidance (i.e., identified as a site with potential and that is
sustainable); and that it satisfies criteria in Charts 4 through 11 for the appropriate fimc:tions.
Using Chart 2 from the Watershed approach which is an analysis utilized to pick a
mitigation site is not really applicable, as the City of Renton is requiring we conduct the
mitigation on the site where the impact is occurring. In addition, there is no other
available mitigation sites within this drainage basin that is owned by either the City or the
client for use as a mitigation receiving site. Therefore, mitigating on-site is the only
feasible alternative given these constraints.
In regards to Chart 3;
Question 3A: Identify the watershed processes that have been altered within the hydrologic
unit where the mitigation site is located.
Human activities can change watershed processes by changing water flows; introducing
nutrients, pollutants, non-native species, and sediment; and by fragmenting habitats.
Changes in these processes often create problems that can be improved through mitigation
activities. To begin you need to identify the major landscape-scale problems (i.e., alterations
to processes, not structure) that exist in the hydrologic unit where your site is found. This will
help you identify which restoration or enhancement actions will be the most effective in that
hydrologic unit. Check the appropriate column in the following table to identify problems
that might exist. The last column notes if the altered process has already been identified in an
existing watershed plan as a problem that needs to be addressed
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Sewall Wetland Consulting, Inc.
February 24, 2014
Page 3
The current flooding events within the Soos Creek drainage are generally not increasing due
to the current use of modern stonn water facilities within the basin. However, there still is
some increase as there is more water getting to the basin faster in stonn events.
There is less eutrophication in rivers and streams in the basin primarily from removals of
livestock and old septic systems.
Water quality has been reduced in the basin to a degree.
Some stream and bank erosion does occur within the basin.
Habitat has become more fragmented as the area's population grows and more development
occurs.
Question 3B: Will the mitigation result in a wetland of the appropriate hydrogeomorpllic
(HGM) class for the landscape setting?
Wetland mitigation sites are sustainable only if the type of wetland being proposed is
appropriate for its position in the landscape. The HGM classification of wetlands is based on
characteristics of water movement and position in a landscape. Therefore, it can be used to
idenlify appropriate wetland types for different locations in a hydrologic unit.
Yes, we will be mitigating for depressional wetlands with a depressional wetland
mitigation area.
Question 3C: Will the primary source of water to the mitigation site be appropriate for the
HGMclass?
Groundwater and direct precipitation will be the source of hydrology for the wetland
mitigation site as was the source for the impacted wetlands. Hydro logic monitoring of the
mitigation site has shown that surficial groundwater elevations in the mitigation area will
sufficiently hydrate the creation area with soils saturated to the surface and some standing
water in the growing season.
Question 3D: Will the site have an adequate supply of water to maintain a wetland without
engineering the delivery of water that would require long term control or maintenance?
The surficial groundwater monitoring and proposed grades should create a wetland area that
will require no additional or artificial source of water to maintain its viability. It is thought
that Wetland A which is located within the area of an old mine is discharging water from
historic mining and as such there is an abundant supply of water in this area.
Question 3E: Will the mitigation activities maintain hydric soill, if they exist, at the site?
Removing hydric soils can decrease the potential for success of we/land restoration. Hydric
soils often contain a seedbank of wetland plants that supplement any planting you may
propose.
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Sewall Wetland Consulting, Inc.
February 24, 2014
Page 4
Hydric soils from the filled wetlands will be mixed with topsoil and utilized in the newly
created wetland maintaining viable seedbanks.
Question 3F: Can the mitigation be designed to control aggressive plant species?
There is currently not a predominance of aggressive invasive or weedy species in the area
of the proposed mitigation or the two wetlands that will be connected together with the
creation. Standard invasive species control will be utilized in the mitigation area which
has proven successful in other mitigation sites.
Regarding the appropriate Charts 4-11;
Cb,ut .$: Goal~ lmp10Ying H~·drology functiom in Depn:-s5ionill Systems Outside of floodplains
..
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Fieldbrook/# 11-121
Sewall Wetland Consulting, Inc.
February 24, 2014
Page 5
Chari".': Go;1J -ImprnYin:g \Yate,r Quality (\YQ) Functiom in Depn?ssional ~ystNm Out'i.ide of lloo(lplaim.
. 111 ·---
Chart 10: Goal -lmpro,ing SpiKitis Ridllless of \Yildlift'
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Sewall Wetland Consulting, Inc.
February 24, 2014
Page 6
-··-·-
........... ··· ... · . . . ' . ' ' .
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This sequencing requires addressing the following criteria;
a. Avoid any disturbances to the wetland or buffer;
C.nlrel.,..,......qlNHw~,-,j• ...:I_.• --~.11:KciaW-ai
years-~.-IPt,.liliAf.•..,.,...
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The site contains three small wetlands which the developer proposes to fill and mitigate
for through the creation of a new wetland area and enhanced buffer areas for the existing
and remaining wetlands A, B & C in the eastern third of the site. Wetland F located on
the western side of the site is Category III wetland measuring 1595sf. Due to the
requirement to provide a secondary fire access directly out to I 08 1h Ave S.E. the
developer is unable to avoid direct impact to this wetland. Wetland E, located in the
center of the site and adjacent to S.E. 172nd St. measures 68sf and is rated as a Category
IV wetland. Due to the requirement to dedicate and construct the other half of the S.E.
172"d St. ROW the developer is unable to avoid direct impacts to this wetland. Wetland D
is located generally in the center of the project and is rated as a Category III wetland
measuring 767lsf.
b. Minimize any wetland or buffer impacts;
The developer previously attempted to plan roadways and improvements around Wetland
D, however the location and shape of the wetland impacted the vehicular circulation and
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Sewall Wetland Consulting, Inc.
February 24, 2014
Page 7
building locations to such an extent that the project would not be financially feasible to
construct.
c. Restore any wetlands or buffer impacted or lost temporarily; and
Restoration of Wetland Din this location would not be feasible due to the location of the
impacts and configuartion of the parcel and remaining wetland.
d. Compensate for any permanent wetland or buffer impacts by one of the following
methods:
i. Restoring a former wetland and provide buffers at a site once exhibiting
wetland characteristics to compensate for wetlands lost;
This is not applicable to this site as no historic wetlands are located on the property.
ii. Creating new wetlands and buffers for those lost; and
A total of9,334sfofwetland will be filled.
US Army Corps of Engineers Required Mitigation
Using the recommended ratios from Table la, of the W ADOE Publication Wetland
Mitigation in Washington State Part 1, (WADOE March 2006 Pub. #06-06-01 Ja)
Table 1
Wetland Size Category Vegetation Ratio Required
Type Wetland
Creation
D 767lsf III Forested 2:1 15342sf
E 68sf IV scrub-shrub 1.5:1 102sf
F 1595sf Ill scrub-shrub 2:1 3190sf
Total 9,334sf 18,634sf
As described above, based upon the required USA COE and W ADOE ratio, a total of
l 8,634sf of wetland is required to be created.
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February 24, 2014
Page 8
The proposed mitigation will create 25,430sf of wetland, which exceeds the required
USACOE ratios by 6,796sf. The extra wetland being created over the WADOE
recommended ratios is a result of the City of Renton having a higher mitigation ratio
requirement than the Corps.
As seen in Table 2 below, using the three main functions from the W ADOE Rating
System recognized by the Corps, a substantial functional lift will be attained from the
connection of Wetlands A and C with 25,430sf of additional wetland over the existing
functions of the proposed fill wetlands.
Tbl2F f IC a e unc 10na omoarison o f. d 1moact wet an s an d orooose d m,h ahon
Wetland Area Flood Species Water Hydrologic Habitat
Storage Richness Qual. Function Function
capacitv Function
WetlandD 7671sf 3800cuft 5 svecies 12vts 8vts 13vts
WetlandE 68s( 34cuft 2 svecies llvts 4vts JOvts
Wetland F 1595sf 500cufi 5 svecies 20pts 8vts llpts
Provosed 25430sf 7600cuft 15 soecies 24ots 20ots 21 ots
Functional +16096sf +3266cuft +8species* +9pts +12pts avg +9pts
I Lift av!! av!!
*only 7 different species were found (excluding exotic/invasives) in Wetlands D, E &F
The newly created wetland will connect to existing Category lil wetlands (Wetlands A
and C) and provide enough lift that this wetland will now be considered a Category II
wetland under the W ADO£ rating system. This is a substantial lift in function, surface
water storage and species richness over the fill of Wetlands D, E & F, which are
generally low value Category III and JV wetlands.
Hydrologic monitoring of mitigation site and general construction overview
Category
III
IV
ill
11
+1
Cate!!orv
To compensate for the impact to 9,334sf of Category III & IV wetland, we will create
25,430sfofwetland between Wetlands A and C. This results in an overall wetland
mitigation ratio of 2.72:1 (created wetland:impacted wetland). This mitigation will
create Category II wetland for a combination of Category Ill and IV wetland impacts. As
depicted on the attached Final Mitigation Plan, 25,430sf of area will be excavated out to a
similar depth to the existing wetland in two areas to intercept the surficial groundwater
table and create conditions favorable to create wetland hydrology.
A series of 6 monitoring pits/wells were located within the proposed wetland mitigation
area. These were monitored with weekly site visits from April of2012-August 2012 as
well as March and early April of 2013. At each of these points soil saturation and water
table levels were measured to determine what surficial groundwater elevations are, to
facilitate designing grades for the new wetland creation area. What we found was that
within the proposed creation area, groundwater levels in the early growing season area
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February 24, 2014
Page 9
between 14" -30" below the existing surface (see table below). It is assumed in the very
early growing season (February and March) the groundwater elevations are shallower
than the measurements we took, meaning the groundwater elevations are closer to the soil
surface.
As shown on the attached Final Mitigation Plan Sheets W I-W3, we utilized these
existing groundwater contours to create the new grades for our mitigation site. As can be
seen by the grades and associated cross-sections, the grades will remove soil down to the
existing groundwater elevations to create wetland areas with soils saturated to the surface
for the early growing seasons, to also include flat areas that will hold some shallow l "-3"
of surface water to provide a variety of wetland hydro logic regimes from saturated, to
seasonally flooded. The fact that the excavation is being brought to the higher levels of
groundwater within the growing season, and will not cut into the surficial groundwater
table, should alleviate the concern of intercepting and draining off this water. All we are
doing is removing the surface soil above the existing sloping groundwater table to make
those saturated soils closer to the surface. Soil disturbance of the groundwater retaining
portion of the soil column will not occur.
Although creation of a slope type wetland is not the most conventional or common
mitigation method, it is a feasible method of wetland creation when conditions warrant its
use. Our company has been involved in two larger wetland creations using this type of
concept, most recently a 3 acre wetland creation with over 10' of vertical drop across the
landscape in sloping of the creation area (see Snohomish County Parks Centennial Trail
II mitigation plan reviewed and approved by Jonathan Smith of the Corps). By using the
same method of removing soil down to the level of the highest groundwater elevations as
is proposed in the Fieldbrook project, we successfully created a 3 acre sloping wetland in
the previously described project.
Table 3. Groundwater elevations below surface o 'hydro/o, v monitorin!! ooints 2012
Monitor DATE
point&
elev.
4/13 4/27 5/11 5/24 6/7 6/28 7/12
A417.5' -15 -14 -15 -20 -26 dry dry
B418' -17 -16 -16 -22 -27 drv drv
C417' -20 -18 -17 -20 -25 dry dry
D416.5' -14 -14 -14 -16 -20 drv drv
E418.5' -27 -26 -24 -30 -36 dry dry
F418' -21 -22 -20 -28 -36 drv drv
Note: All elevations indicate the elevation of the saturaled capillary fringe of soil
saturation observed in hydrology monitoring points.
8/12
drv
drv
dry
drv
dry
drv
Table 4. Groundwater elevutions below surface o
Monitor DATE
point&
elev.
3/15 3/29 4/9
A417.5' -12 -10 -15
B418' -15 -15 -14
C417' -17 -16 -18
0416.5' -10 -11 -13
E418.5' -23 -20 -23
F418' -18 -19 -20
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February 24. 2014
Page 10
r hvdrolo• " monitorinf! ooints 2013
Note: All elevations indicate the elevation of the saturated capillary fringe of soil
saturation observed in hydrology monitoring points.
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Fieldbrook/#11-121
Sewall Wetland Consulting, Inc.
Erilting •uifaa
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l~I~ ::::::::::::::::::::::::::::::::~~::::~::::::::::~~,:;;:v=:~::::::::::::::::::::::::::::::::::::;;:.,::::~I :::::::::::::::::::::::::::;I
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February 24, 2014
Page 11
-•Apptoxirnat.
groundwater .ievation
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A small berm will be placed between the wetland creation area and Wetland B. This will
prevent (in the unlikely case of surface water overtopping the edge of the wetland) the
wetland creation area between Wetlands A and C from draining into Wetland B.
Hydro logic monitoring will be conducted using peizometers in the proposed mitigation
area through the winter and spring to verify groundwater elevations. This area will then
be graded back at a slope no steeper than 3:1 (horizontal:vertical). The area will then be
planted with a mix of native trees, shrubs and herbaceous species and will also include
several habitat features (logs and snags) to increase its habitat function.
As depicted on the attached Fieldbrook Commons Mitigation & Grading Plan (dated 9-
23-13), a split rail fence will be placed at the edge of the wetland buffer. There are no
living spaces or recreational space next to the wetland or its buffer limiting use of this
area. However, the City of Renton is requiring that the applicant provide a trail through
the wetland buffer as depicted on the plan. We have moved this trail to the north,
splitting the buffer area between the wetland creation area and Wetland B to the north to
maximize distance of the trail from the wetland as best possible.
Signage and a split rail fence along the trail indicates the character of the critical area and
will discourage intrusion into the wetland or buffer.
All lighting will be located outside the wetland and buffer. All lighting in the developed
portion of the site will be directed away from the wetland and its associated buffer.
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February 24, 2014
Page 12
The goal will be to create at least 25,430sf of area meeting all three wetland criteria
(hydric soils, hydrophytic vegetation, and wetland hydrology) as specified in the
Washington State Wetlands Identification Manual (W ADOE, March 1997) and the
Western Mountains, Valleys and Coast region Supplement (Version 2.0) dated June 24,
2010. All disturbed buffer areas will be restored with a dense planting of native trees and
shrubs. The resulting wetland creation area will be monitored for 10 years. The creation
area will be delineated at Years 5 and 10 to determine if 25,430sf of area meeting
wetland criteria has been created. If there is not at least 25,430sf of wetland created, the
shortage will be made up with either;
1. Fixing any small grading or hydrology issue which may be impacting the overall
size of the creation area, or;
2. Purchase of mitigation credits from the King County Fee program or other similar
program at that time.
Site Protection Instrument
The entire mitigation site as well as the buffer and undisturbed wetlands will be placed
within a Native Growth Protection Easement (NGPE) and recorded on title prior to
occupancy of the project.
Long Term Maintenance
The mitigation area will be monitored and maintained over the 10 year monitoring
period. This will include trash removal, weed and invasive species removal, repair of
fencing and signage. After the required 10 years maintenance and monitoring period, the
facility operating manual will include a description of the NGPE are and what type of
maintenance can and should occur within this area. Management of the facility will be
responsible for this work following the 10 year monitoring and maintenance period.
PROPOSED MITIGATION
Fieldbrook/#11-121
Sewall Wetland Consulting, Inc.
1.0 MITIGATION PROJECT OVERVIEW
February 24, 2014
Page 13
To compensate for the fill of a 9,334sf Category III & IV wetlands, it is proposed to
create 25,430sf of wetland between Wetlands A and C. Wetlands to be filled include
Wetland D (7,67lsfCategory III wetland), Wetland E (68sfCategory IV wetland) &
Wetland F (l,595sfcategory III wetland).
2.0 MITIGATION GOALS
2.1 Mitigation Goals
The mitigation proposal is to connect Wetlands A and C with an area of25,430sf of
wetland. The wetland creation areas will be densely planted with native vegetation. The
use of diverse native plantings are expected to significantly improve the overall function
of the wetland and buffer as it will remove dense thickets of exotic blackberry as well as
add emergent and shrub plant communities into what is now, a single class forested
wetland.
2. 2 Mitigation Goals
2.2.1 Create 25,430sf of emergent, scrub shrub and forested wetland.
3.0 CONSTRUCTION SEQUENCE
The construction sequence of this project will be implemented as follows:
3.1 Pre-construction meeting
3.2 Construction staking
3.3 Construction fencing and erosion control
3.4 Clearing and grading
3.5 Stabilization of mitigation area
3.6 Plant material installation
3. 7 Construction inspection
3.8 Agency approval
3. 9 10 year Monitoring inspection and reporting
3.10 Silt fence removal
3.11 Project completion
3.1 Pre-construction Meeting
A pre-construction meeting will be held on-site prior to commencement of construction,
to include the biologist, the City, and the contractor. The approved plans and
specifications will be reviewed to ensure that all parties involved understand the intent of
the construction documents, specifications, site environmental constraints, sequences, and
inspection requirements.
•
3.2 Construction Staking
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February 24, 2014
Page 14
The limits of clearing and grading near the critical areas will be marked in the field by a
licensed professional land surveyor prior to commencement of construction activities.
3.3 Construction Fencing & Erosion Control
All erosion control measures adjacent to the critical areas, including silt fencing and
orange construction fencing, will be installed. Erosion control fencing will remain
around the mitigation area until clearing, grading and mulch placement are complete in
upland areas outside the critical areas.
3.4 Clearing & Grading
Clearing and grading in and near the existing sensitive area will be per the approved Final
Mitigation Plans.
3.5 Stabilization of Mitigation Area
All graded areas in the wetland or buffer will be stabilized with mulch upon completion
of grading. Orange construction fencing and erosion control fences will be restored (if
necessary) and placed around the critical areas.
3.6 Plant Material Installation
All plant material will be planted by hand per detail and Construction and Planting Notes.
The Mitigation Plan specifies the required size, species, quantity, and location of plant
materials to be installed. The contractor will mulch areas disturbed during the planting
process. Upon completion of the planting, the erosion control fencing will be restored
and repaired. Plant substitutions or modifications to locations shall be approved in
writing by the Owner's biologist prior to installation.
3. 7 Construction Inspection
Upon completion of installation, the biologist will conduct an inspection to confirm
proper implementation of the Mitigation Plan. Any corrections, substitutions or missing
items will be identified in a "punch list" for the landscape contractor. Items of particular
importance will be soils in pits, pit size, plant species, plant size, mulch around pits, and
tree staking.
Upon completion of planting, if installation or materials vary significantly from the
Mitigation Plan, the contractor will submit a reproducible "as-built" drawing to the
Owner. The As-built and installation sign-off report will be submitted to the Corps at
that time.
3. 8 Agency Approval
Following acceptance of the installation by the City, the City biologist should prepare a
letter granting approval of the installation.
3.9 Monitoring
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February 24, 2014
Page 15
The site will he monitored for IO years to insure the success of the mitigation project. If
additional years of monitoring are required by the Corps, the plan will be revised to
reflect this change. Any areas of temporary impacts that require restoration will be also
monitored for the full IO year monitoring period.
3.10 Silt Fence Removal
Erosion control fencing adjacent to the mitigation area will remain in place for at least
one year, and/or until all areas adjacent to the mitigation area have been stabilized. The
City's Biologist may recommend that the fencing remain in place for a longer duration.
4.0 CONSTRUCTION AND PLANTING NOTES
4.1 Site Preparation & Grading
4.1.1 The Landscape Contractor will approve existing conditions of subgrade prior to
initiation of any mitigation installation work.
The Landscape Contractor will inform the Owner of any discrepancies between the
approved construction document and existing conditions.
4.1.2 The General Contractor will flag the limits of clearing with orange construction
fencing and will observe these limits during construction. No natural features or
vegetation will be disturbed beyond the designated "limits of clearing".
4.1.3 The Landscape Contractor will hand grub all non-native invasive plant species
including the removal of root crowns. These species may include, but are not limited to
Himalayan blackberry, evergreen blackberry, English ivy, and English holly. Weed
debris will be disposed of off-site.
4.1.4 The wetland area will be excavated to the depths shown on the Final Mitigation
Grading Plan and brought to final grade with 8" of topsoil. The biologist will be on-site
to confirm the grading is acceptable for planting. A total of 4"-6" of compost will be
incorporated into the upper 12" of all graded areas in the wetland creation area.
4.2 Plant Materials
4.2.1 All plant materials will be as specified in the plant schedule. Only vigorous
plants free of defects, diseases and infestation are acceptable for installation.
4.2.2 All plant materials will conform to the standards and size requirements of ANSI
Z60.l "American Standard for Nursery Stock". All plant materials will be native to the
northwest, and preferably the Puget Sound Region. Plant materials will be propagated
from native stock; no cultivars or horticultural varieties will be allowed. All plant
materials will be grown from nursery stock unless otherwise approved.
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February 24, 2014
Page 16
4.2.3 No balled and burlapped, or bare root plantings will be used. Only container
stock to be used.
4.2.4 All plant materials stored on-site longer than two (2) weeks will be organized in
rows and maintained by the contractor at no additional cost to the owner. Plant materials
temporarily stored will be subject to inspection and approval prior to installation.
4.2.5 Substitution requests must be submitted in writing to the Owner and approved by
the Owner's biologist in writing prior to delivery to site.
4.2.6 All plant materials will be dug, packed, transported and handled with care to
ensure protection from injury. All plant materials to be stored on site more than 24 hours
will be heeled into topsoil or sawdust. Precautionary measures shall be taken to ensure
plant materials do not dry out before planting. Wetland plants will be shaded and
saturated until time of installation. Immediately after installation the mitigation planting
area will be saturated to avoid capillary stress.
4.2.7 The contractor will verify all plant materials, the quantities shown on the planting
plan, and the plant schedule. The quantity of plant materials shown on the plan takes
precedent over the quantity on the plant list.
4.3 Plant Installation
4.3.1 All plant materials must be inspected prior to installation to verify conformance of
the materials with the plant schedule including size, quality and quantity. Any plant or
habitat materials deemed unsatisfactory will be rejected.
4.3.2 All plant materials delivered and accepted should be planted immediately as
depicted on the mitigation plan. Plant materials not planted within 24 hours will be
heeled-in. Plant materials stored under temporary conditions will be the sole
responsibility of the contractor. Plants will be protected at all times to prevent the root
ball from drying out before, during, or after planting.
4.3.3 All planting pits will be circular with vertical sides, and will be sized per detail on
the mitigation plan and filled with pit soils approved by the Owner's biologist. Planting
pits shall not be deeper than the root ball. If native soils are determined to be
unacceptable by the Owner's biologist, pit soils will be amended with Cedar Grove
mulch or equivalent.
4.3.4 No fertilizers will be used within the wetland. In buffer areas only, install
"Agriform", or equal plant fertilizer to all planting pits as specified by manufacturer.
Fertilizers are allowed only below grade in the planting pits in the buffer areas. No
sewage sludge fertilizer ("SteerCo" or "Growco") is allowed in the mitigation area.
-----------------------------,
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February 24, 2014
Page 17
4.3.5 All containerized plant materials will be removed from their containers carefully
to prevent damage to the plant and its roots. Plants removed from their containers will be
planted immediately.
4.3.6 All plant materials will be placed as shown on the approved mitigation plan. If
the final installation varies from the approved mitigation plan, the contractor will provide
a reproducible mylar as-built of the installed conditions. All plant material will be
flagged by the contractor.
4.4 Planting Schedule and Warranty
4.4.1 A fall-winter installation schedule (October I st -March 15th ) is preferred for
lower mortality rates of new plantings. If plant installation occurs during the spring or
summer (March 15th -Oct. 1st) a temporary irrigation system will be required, unless
the area can be sufficiently hand-watered.
4.4.2 All disturbed areas will be protected with an arborists mulch to a minimum depth
of six inches.
4.4.3 The installer will warrant all plant materials to remain healthy and alive for a
period of one year after final acceptance. The installer will replace all dead or unhealthy
plant materials per the approved plans and specifications.
4.5 Site Conditions
4.5.1 The installer will coordinate with the Owner and the Owner's biologist for
construction scheduling.
4.5.2 Landscape installation will begin after the City acceptance of grading and
construction. The Owner will notify the Owner's biologist of acceptance of final
grading.
4.5.3 Silt fences will be installed as shown on the approved mitigation grading plans.
The installer is responsible for repair and replacement of silt fences disturbed during
plant installation. No equipment or soils will be stored inside the silt fences.
4.5.4 After clearing and grading is complete in the mitigation area, exposed soils will
be seeded or mulched. Orange construction fence will be placed around the mitigation
area to prohibit equipment and personnel in the mitigation area.
4.5.5 Final grading will be based upon soil conditions found during excavation of the
mitigation area.
a •
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4.5.6 All plant material will be planted with suitable soils per planting details. Soils
from planting holes will be spread and smoothed across the mitigation area.
5.0 MAINTENANCE PROGRAM
This maintenance program outlines the program, procedures and goals for mitigation of
the stream and buffer impacts at the mitigation site. This maintenance program will be
the responsibility of the project owner through the duration of its ownership of the
mitigation area, or throughout the duration of the monitoring period, whichever is longer.
The maintenance contractor will complete the work as outlined below.
5.1 Maintenance Work Scope
5.1.1 To accomplish the mitigation goals, normal landscaping methods must be
modified to include:
a.No mowing or trimming of ground cover or vegetation in the mitigation
area.
b. No placement of fertilizers in the mitigation area.
c. No placement of bark mulch or equivalent in the mitigation area,
except as noted in the planting details.
d. No placement of grass clippings, landscape debris, fill or ornamental
plant materials in the mitigation area.
5.1.2 Work to be included in each site visit:
a. Remove all litter including paper, plastic, bottles, construction
debris, yard debris, etc.
b. Remove all non-native and invasive species identified in Table 3-1 of
Sheet W-3 of the Final Mitigation Plan within the mitigation area. All debris is to be
removed from site and disposed in an approved landfill.
c. Repair silt and/or permanent fencing and signage as needed.
5.1.3 Work to be completed on an annual basis includes:
a. Areas containing non-native/invasive species identified in Table
3-1 of Sheet W-3 of the Final Mitigation Plan should be controlled by hand cutting and
removing the root crowns for species such as Himalayan blackberry. Following hand
removal, treating re-sprouting invasive/non-native species with a glyphosphate herbicide
such as Roundup or Rodeo by a licensed applicator can be utilized.
b. Replace dead or failed plant materials. Replacement plantings are to be
of same species, size and location as original plantings. Plantings are to be installed
during the dormant period.
• •
5.2 Maintenance Schedule
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February 24, 2014
Page 19
The Owner will conduct all items listed in the Maintenance Work Scope on an annual
basis. Additional work may be required per the Monitoring Report and as approved by
the Corps. Additional work may include removal of the grasses around each shrub and
tree, installation of wood chips at each shrub and tree base and erosion control protection.
5.3 Watering Requirements
5.3.1 Watering with a temporary irrigation system will be required during the first
spring and summer after the installation. The temporary irrigation system may be
removed after the first year providing the plantings are established and acclimated to on-
site conditions.
5.4 Close-out of Ten-Year Monitoring Program
Upon completion of the monitoring program and acceptance of the wetland mitigation by
the Corps, the maintenance of the project will be reduced to include removal of litter and
debris, repair of perimeter fencing and signage, removal of noxious weeds and
undesirable vegetation, and repair of vandalized areas.
6.0 WETLAND AND BUFFER 10 YEAR MONITORING PROGRAM
6.1 Sampling Methodology
The created wetlands and their associated buffers will be monitored once per year over a
ten-year period, starting with the first year after the plants have been installed, and as
required by the Corps. Monitoring will be conducted using the techniques and
procedures described below to quantify the survival and relative health and growth of
plant material. A monitoring report submitted following each monitoring visit will
describe and quantify the status of the mitigation at that time. Vegetation monitoring will
be conducted in August or September during monitoring years. Year 1 monitoring will
occur at least one calendar year after installation sign-off.
6.1.1 Hydrology
Wetland hydrology will be monitored using seven (7) piezometers per USACOE
specifications. These will be located within the restoration area to be placed at the time
of the installation sign-off by the biologist. Surface water level or ground water
saturation depths will be measured at these stations to determine if wetland hydrology has
been successfully attained. As is noted in the Corps of Engineers Wetlands Delineation
Manual (Environmental Laboratory, 1987) and the Western Mountains, Valleys and
Coast region Supplement (Version 2.0) dated June 24, 2010, wetland hydrology is
defined as inundation or soil saturation (usually within 12" of the surface) during the
growing season. The growing season for this area is generally defined as the period
. .
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between the middle of March and the middle of November. However, plant growth often
occurs earlier in the year and sound professional judgment will be needed to determine
when the growing season is taking place at the site. Hydrology will be monitored twice a
month from March I st through May 30th of each year.
Wetland hydrology will be considered successfully created if wetland hydrology is
observed inundating or saturating the soil within 12 inches of the surface during the
growmg season
6. l.2 Vegetation
The vegetation monitoring consists of inspection of the planted material in late summer
or early fall (August-September) to determine the health and vigor of the installation, as
well as coverage estimates. All the planted material in the wetland and buffer will be
inspected during each monitoring visit to determine the level of survival of the
installation.
All plants will be inspected and recorded as to whether they are alive or dead based upon
the "as-built" in Years I & 2. In Years 3-5, coverage estimates will be used to determine
success of the vegetation component.
A total of 19 permanent 3.0m rectangular monitoring plots will be located within the
mitigation area as depicted on Sheet W-3 to monitor shrub and tree species coverages.
Within each of these 3.0m plots, the emergent plant community coverage of vegetation
will be measured with 0.25m rectangular plots. Estimates of coverage percentages will
be made within these plots.
Photographs of the mitigation area will be taken from 6 photo points to be located during
the installation sign off as well as at each permanent monitoring plot. Photographs will
be taken at each of the monitoring and included with the monitoring report for each year
from these points.
During years 1 & 2 of the monitoring, replacement plants as well as dead plants will be
flagged with distinctive flagging to distinguish what plants these are.
,,
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6.2 STANDARDS OF SUCCESS
PERFORMANCE STANDARDS
ITIM YUM TO ll MONITOND
........_, .. _
wnt.AND HYDAOLOGY YEA.RS l, 2, J, 4. 5, 7 AND 10 SOILS WtTHIN CJl:EATU> Wtfl.ANO Aft(AS SHAU. IE SA'T\JRATUl TO TI-E SURFACE., HA\lt SHAU.OW
ICUAHD WIT LAND AND GIIOUNDWA.Tlft i.ESCNT WITHIN 12 INOIESOI' THE SOil 5URFI£[, AND/Oft HAVE SURFAC.E PONDING
WETlAND A/WETlAND C) PRESENT FOR. A.T LEAST FOUR (4) CONSf:CUTIVE WIU:S OUFUNG THE GIOWIHG SlASON WHEN M.!Nf:.IJJ. IS
LESS TAAN OR EQUAL TO TH£ MEAN FOR THE Pf.RIOO OF·A\IAILAIU RECORD.
W£TlAND D£UNEAT10N VU.RS SAND 10 PERFORM OElWEATION Of WeT\ANO A, WETLAND C, AND WE TI.AND at.EATION A/I.EA lO OETEAMINE If.
WHnHER WETLAND A ANO WET\AND CME IYRCTED IY THE WET\AND WATION, PEkfORll4ANCt
STANDAAD tS SATISFIED IF THERE IS NO CHANG£ TO Will.ANO llMrri.
NAnV£Vf6ETATION Vt.AAS l, 2, 3, 4, S, 7 AND 10 TRE[ AND SHU SPEm
(OEATED WETIAND/ {TO octUR IN o\UGVST OR • tooi5UIMVAL YINSTAUEDPLANTSTOCK.alTtR TffE mSTGRC7NINGSEASON.
ENHANCEO WETLAND-8UfFEA) SE'1TM8£ll lf61NNING ONE . 80K SURVIVAL IY INSTAUED PlANT STOCK AFJEft THE SECOND GaOWING SUSON •
YU,R RH.LOWING INfTIAI. • ENHAHCIO IUfFU N.AlfflNG AJI~ MINIMUM MRaNT COVEa lVTJIEESANDSHlUBS: YEAII: 3:
P~NT INSTAUATION.) ~; YEM S: 4S"; YE.U 7: 65"; YEM 10: '°'6. u, TO 20% OF TltE NATIVE WOODY PLANT SPlOES
COVERAGE MAY BE COMPAIS£D OF DESIRAII.E NA.TM COlONIZING SPECIES.
• OIUllOWITI.AND PlNfflNG MEAS; MINIMUM N:IIQ:NT COVEii 8l nus AND SHRU8S: YEA.A!;
!fflli; YEARS: li(Mli; YI.U 7: IC*; YiAfl 10: !lmli. UP TO 2°" Of THE NATM WOOOY PLANT SPECIES
tOVEAAGe MAY IE COMPAISlD OF OfSIRMlE NA.TM COlONWNG SPEOES. . AFTER THE flfTH ~OwtNG SfASON, A MINfMUM Of FOUR ou=m1ENT PLANT $.PECIES Will
COMPfl:ISE GUATfR THAN 109' COYIRAGE.
EME1ENTSas
• Y"AVI CO\/EkAGE IYINSTAUED PLANT STOO:ARUl;THEAI\ST&ROWIHGSEASON. . ~AVllAGf.CO'it:M<il BYINSTAlLEDNANT STOO:AfTfR lHf.Stb at~ seuons. . SOK AVUAG( COYEltAGl IY NA.TM IMIRGlNT PLANT SPECIESAFTP: THE ING SfASON .
• AFRR THl Aflli GROWING SIASON, A MIMMIJM Of lHRIE OJFfl:RtNT Pl.ANT sPECllS WIU.
COMPRISEGRIATlR THAN 1°"COVIRA<ii.
!UIU l., t, I.•, J, 'I NII~ JO
NATIVE VtG£TATION
{TO«oMIN.tU:tJCTM . 100%SURVIVAI. SYINSlALLEOPLANTSTOO(AfTHl THE FIRST GR.OWING SEA.SON . lllf'ilMlh~ll,1> .. 'l-..,;:)Nl
fRISlORED WETlAND IUFFEII.) ....,. fQu.awui. ""'1'V\s . 80% WRVIVN. IY INSTAlllD P~ STOOt Aflt:R TM~ fHIROGROWING SEASON .
tUIII I IN:)IM.J.l ,~l
NOXIOUS WEED SPEO£S YEARS 1, 2, !,4, S, 7, ANO 10
LfSSTHAN 10% COVf:IAGI IV ALLCI.ASrA", "I", ANO "C" NOXIOUSWffDS{INO..UDING NON-M'GIAATtD
"I" ANO "C" NOXIOUS WEED5,) IDENTIFIIDON THl LATUT llNG COUNTY NOXIOUS WEED UST. NOXIOUS
WlfO CX>HTlOL PERJORMANCE STANDARDS ARE UMfrED TO ltlAHTED AREAS ONLY.
7.0 CONTINGENCY PLAN
7.1 A contingency plan can be implemented if necessary. Contingency plans can
include re-grading, additional plant installation, erosion control, modifications to
hydrology, and plant substitutions including type, size, and location.
7.2 Careful attention to maintenance is essential in ensuring that problems do not
arise. Should any of the site fail to meet the success criteria, a contingency plan will be
developed and implemented with the City approval. Such plans are prepared on a case-
by-case basis to reflect the failed mitigation characteristics.
7.3 Contingency/maintenance activities will include, but are not limited to:
-Replacing all plants lost to vandalism, drought, or disease, as necessary.
-Replacing any plant species with a 20 percent or greater mortality rate with the same
species or similar species approved by the City Biologist.
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February 24, 2014
Page 22
-Irrigating the mitigation area only as necessary during dry weather if plants appear to be
too dry, with a minimal quantity of water.
-Reseeding wetland and buffer areas with an approved grass mixture as necessary if
erosion/sedimentation occurs.
-Removing all trash or undesirable debris from the wetland and buffer areas as necessary.
If you have any questions regarding this report, please call us at (253) 859-0515 or at
esewall@sewallwc.com .
Sincerely,
Sewall Wetland Consulting, Inc.
Ed Sewall
Senior Wetlands Ecologist PWS #212
---'1R{®mi~(Q)ID1 (€D
Planning Division
~ [p [p [R1 (Q) w [E [g)
By ff@. Awrl)w d
Date ~e:<54 Th/bee e)J/ /I~
Spring Brook Coal Company
The City of Renton ha s a Jon g history of coa] minin g beginning in 18 73 with the di sc overy of the first coa l seam and th e formation of the Renton Mining Company, Jn c. by Erasmus M. Smithers and Captain
Willi am Renton. The Hen son Hill area was hom e to th e Spring Brook Coal Company, which indud cd the J\o. 3 coal seam which opened in th e early 1930s. Th e upp er and Jow er splits of the No. 3 coal scam
underlay a portion of thi s site. Coal minin g remain ed one the area's mo st important economic indu stri es throughout the 1930s and many oth er small bu sin esses dev eloped to serve th e coal miners and their
familie s. With the advent of hydro-el ec tric power, electricity began to replace coal as an energy sour ce an d th e coal minin g indu stry in West ern Washington dwindl ed. The last active mine in the region was
closed in 1974. As you walk throu gh th e wetl and s on this site, yo u will still see remnants of the coal mining operation throughout th e land sca pe, indudin g the ]arg e coa l tailing s pil e locat ed lo th e south .
Cl 111.enton Hi,tory Muteum, All ri,ghts resenoed.
Photos Courtesy of th e Renton Hi stori cal Soc iety
--Fl A.-V A.N'A.
~TRAl LS
City or Renton
Pla1111inq f1ivision
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SIDE 1
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Pacific W i llow (Sa lix Lasi andr a)
Sa l monberry (Rubus Spect ab ili s)
Mallar d Duck (Male)
Vegetation and Wildlife of the A vana Trails
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Black Twinberry (Lo nice r a lnvolucra)
Great Bl ue He r o n
Wetland Creation and Restoration Project
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Western Cr abapple (Malux Fusca )
Indi an Pl u m (Oe m leria Ce r as ifor m is)
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Ameri can W i geon
Oregon Ash (Fraxin us Latifoli a)
Slou gh Sedge (Carex Obnupta)
Beaver
Sitka W illow (Sa lix Sit che n sis)
Sp ike Rus h (El eocaris Parvula)
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Re d-osier Dogwood (Cornus Stolonifera)
Sma ll Fruited Bu l rush (Sc i rpus M i crocarpu s)
Muskrat
SIDE 2