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Critical Area Mitigation Plan for
Gurudwara Singh Sabha of Washington
5200 Talbot Road South, Renton, Washington
View west of gravel fill removal and wetland and stream buffer restoration areas
(October 18, 2016).
September 2017
Prepared for: Prepared by:
Gurudwara Singh Sabha of Washington Krippner Consulting, LLC
5200 Talbot Road South PO Box 17621
Renton, WA 98055 Seattle, WA 98127
Critical Area Mitigation Plan Gurudwara Singh Sabha of Washington
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Table of Contents
Plan Overview .......................................................................................................................... 3
Site Description ....................................................................................................................... 3
Critical Areas and Buffers .................................................................................................... 3
Goals ............................................................................................................................................ 3
Objectives .................................................................................................................................. 4
Performance Standards ........................................................................................................ 4
Plant Schedule .......................................................................................................................... 5
Construction Sequence .......................................................................................................... 6
Planting Specifications .......................................................................................................... 7
Compliance Monitoring Plan ............................................................................................. 11
As-Built ............................................................................................................................................... 11
Annual Compliance Monitoring ................................................................................................. 11
Contingency Plan ................................................................................................................... 11
Maintenance Plan .................................................................................................................. 12
Photos ....................................................................................................................................... 13
Figure 1. Neighborhood Detail Map
Figure 2. Mitigation Areas
Figure 3. Planting Areas
Appendix A: Mitigation Plan Drawings
Sheet 1 of 3 – Erosion Control Plan
Sheet 2 of 3 – Excavation and Planting Plan
Sheet 3 of 3 – Cross Sections & Profiles
Critical Area Mitigation Plan Gurudwara Singh Sabha of Washington
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Plan Overview
Krippner Consulting, LLC has prepared this critical area mitigation plan for the
Gurudwara Singh Sabha of Washington Sikh Temple at 5200 Talbot Road South
(Parcel #3123059075) in Renton, Washington (Figure 1) to improve the functions
of wetland, stream, and buffer areas on this site. This mitigation plan is required
because gravel fill was placed in the stream and wetland buffer in violation of
Renton Municipal Code (RMC). This plan also provides wetland and buffer
mitigation for a recently completed sidewalk extension project along Talbot Road
South. Gravel fill and non-native invasive plants will be removed, disturbed soils will
be enhanced, stream banks will be re-contoured where needed to stabilize slopes
and reduce erosion, and native plantings will be installed to restore and improve
wetland and stream buffer area conditions. Some areas will be seeded with native
meadow plants. The wetland boundary and stream centerline were identified by
Krippner Consulting in April 2016, and surveyed by Core Design in October 2016.
Site Description
The Gurudwara Singh Sabha of Washington property includes a Sikh Temple,
several additional buildings, asphalt and gravel parking areas, a forested slope east
of the developed areas, a stream along the south site boundary, and a wetland at the
southwest corner. The site is bounded by Talbot Road South to the west, residential
development to the north and south, and a forested slope to the east.
Critical Areas and Buffers
Critical areas and buffers subject to this mitigation plan include Wetland C, a
depressional wetland, approximately 2,894 square-feet in size, a seasonal stream,
and their buffers (Figure 2). The wetland is a Category III wetland with a standard
buffer of 75 feet. The stream is classified as Type Ns with a standard buffer of 50 feet.
Renton Municipal Code allows buffers to be reduced up to 25% with enhancement
that improves critical area functions. The wetland buffer has been reduced to 56.25
feet and the stream buffer has been reduced to 37.5 feet with this mitigation plan.
Gravel fill will be removed where it has been placed in these buffer areas (Figure 2).
All reduced buffer areas will be enhanced by the removal of invasive species and re-
planting and/or re-seeding with native species (Figure 3).
Goals
This mitigation plan has been designed to improve wetland, stream, and buffer
functions on the site in accordance with RMC and best available science. Habitat
functions will be improved with the creation of native meadow/pollinator habitat,
and enhancement of shrub thicket and forested habitats in buffer areas. Water
quality functions will be improved by increasing structural diversity with the
Critical Area Mitigation Plan Gurudwara Singh Sabha of Washington
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addition of native trees and shrubs in the wetland and trees, shrubs, grasses, and
forbs in buffer areas. Hydrologic functions will increase when gravel fill is removed,
stream banks are stabilized, and disturbed buffer areas are enhanced with native
plants. The buffer area adjacent to Wetland C is likely to receive surface water
overflow from the wetland during heavy rainfall events.
Objectives
Enhance at least 1,016 square feet of wetland by removing invasive species, mainly
Himalayan blackberry, and installing native shrubs.
Remove gravel fill and restore native vegetation communities in approximately
8,025 square feet of wetland and stream buffer areas.
Remove Himalayan blackberry, Bohemian knotweed, and other invasive, non-native
plants and enhance native vegetation communities in approximately 13,434 square
feet of stream buffer area.
Stabilize near vertical stream banks to 3:1 slopes where needed to prevent erosion.
Continue removal of non-native, invasive species, including Himalayan blackberry
and Bohemian knotweed, in wetland, stream, and buffer areas during the 5-year
monitoring and management period.
Performance Standards
The stream channel shall be stable, and soils restored to native gravelly sandy loam
following removal of gravel fill and stream bank re-contouring.
At least 90% cover of grasses and forbs shall be achieved in seeded (meadow) areas
during the first growing season and thereafter.
At least 80% survival of installed plantings shall be achieved after the first growing
season (in Year 2). Volunteer plants may be substituted for installed plantings to
meet this standard, if they are native and are providing a similar ecological function.
At least 60% cover of native trees and shrubs shall be achieved in installed planting
areas by the final monitoring year, Year 5.
All buffer and wetland areas shall be managed to have less than 10% cover of non-
native, invasive plants (excluding reed canarygrass) during each of the 5 monitoring
years.
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Plant Schedule
Approximately half the buffer (10,730 square feet) will be planted with native
shrubs and small trees to enhance existing forest vegetation, including black
cottonwood and red alder trees rooted near the stream, and half will be seeded with
native forbs and grasses to create meadow and pollinator habitat. Tree and shrub
spacing is approximately 4 feet on center. Approximately 1,016 square feet of
wetland area will be enhanced with native trees and shrubs.
The Plant Schedule, subject to change in species composition depending upon plant
availability at the time of purchase, is as follows:
Common Name Scientific Name Size Quantity
Tree/Shrub Plantings Wetland Buffer Total
Vine maple Acer circinatum 12-18" 50 50
Douglas hawthorn Crataegus douglasii 18-36" 50 50
Oregon ash Fraxinus latifolia 36"+ 10 40 50
Ocean spray Holodiscus discolor 18-36" 50 50
Black twinberry Lonicera involucrata 36"+ 10 40 50
Tall Oregon grape Mahonia aquifolium 12-18" 100 100
Osoberry Oelmeria cerasiformis 18-36" 50 50
Nootka rose Rosa nutkana 12-18" 100 100
Salmonberry Rubus spectabilis 18-36" 50 50
Sitka willow Salix sitchensis 18-36" 50 50
Red elderberry Sambucus racemosa large 50 50
Snowberry Symphoricarpos albus 18-36 100 100
Totals 70 680 750
Meadow seed mix Percentage lbs
Yarrow Achillea millefolium 15 0.6
Pearly everlasting Anaphalis margaritacea 10 0.4
Common camas Camassia quamash 10 0.4
Tufted hairgrass Deschampsia cespitosa 25 0.9
Idaho fescue Festuca idahoensis 25 0.9
Large-leaved lupine Lupinus polyphyllus 15 0.6
The trees and shrubs listed in the plant schedule are available as bare rootstock
from January through March from Fourth Corner Nurseries, specializing in native
plants. The native seed mix is available from Rainier Seeds Incorporated, listed by
the Xerces Society as a seed source for native plants. The Xerces Society promotes
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pollinator conservation and focuses on the conservation of invertebrates considered
to be essential to biological diversity and ecosystem health. Plants and seeds may be
purchased from these vendors, or from another local vender that specializes in
providing native plants and seeds.
Construction Sequence
1. Install construction fencing along boundary of reduced wetland and stream
buffer. Reduced wetland buffer is 56.25 feet. Reduced stream buffer is 37.5
feet.
2. Remove gravel fill and other garbage and debris including concrete slabs and
imported rocks from protected buffer and wetland areas. This work may be
completed with an excavator.
3. As instructed by the project biologist, remove non-native plants including
Himalayan blackberry and the root mass of any Bohemian knotweed. Haul
Bohemian knotweed to landfill for disposal. This work may be completed
with an excavator. Protect native trees growing near the stream, being
careful to leave their root systems undisturbed.
4. As instructed by the project engineer and project biologist, re-contour
vertical or steep-sided stream banks to make the bank slope more gradual
and stable, approximate 3:1 slopes. Protect native trees growing near the
stream, being careful to leave their root systems undisturbed. Excavator will
stay on north side of stream.
5. Use excess native soil from stream re-contouring to fill in any holes created
from removing Bohemian knotweed root masses.
6. Use compost to rejuvenate soils, where needed, and mix compost into the
native soil.
7. Stabilize slope areas with jut matting near the stream near the upper end of
the project, if needed.
8. Cover exposed soils with at least 3 inches of wood chip mulch in areas to be
planted with trees and shrubs.
9. Cover exposed soils with weed free straw and native grass-forb seed mix in
meadow areas as shown in Figure 3.
10. Install native shrubs and trees in any wetland areas where invasive plants
were removed. The extent of this area is estimated in Figure 3.
11. Install native trees and shrubs in tree/shrub planting areas within the buffer
as shown in Figure 3.
12. Install a split-rail fence to mark the buffer edge. An Ecology concrete block
wall may also be installed, set back from the fence and outer edge of the
buffer, outside of the reduced wetland and stream buffer to prevent vehicle
access into any buffer areas.
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Planting Specifications
The plant installer (may be the property owner) should use these instructions to
ensure that plants are inspected and installed correctly.
PART 1 - GENERAL
1.01 DESCRIPTION: Provide and plant trees and shrubs as shown and specified.
The work includes but is not limited to:
A. Soil Preparation.
B. Plants and Planting.
C. Mulching.
D. Plant Warranties.
1.02 QUALITY ASSURANCE:
A. All plants shall be nursery grown or collected materials that has been
held in a nursery for at least one year. Nursery climatic conditions
must be similar to those in the locality of the project. All plants shall
be weed free at the time of planting.
B. Stock furnished shall be at least the minimum size indicated. Larger
stock is acceptable at no additional cost, and providing that the larger
plants will not be cut back to size indicated. Provide plants indicated
by two (2) measurements so that only a maximum of twenty-five
percent (25%) are of the minimum size indicated and seventy-five
percent (75%) are of the maximum size indicated.
1.03 DELIVERY, STORAGE AND HANDLING:
A. Dig, pack, transport, and handle plants with care to ensure protection
against injury. Inspection certificates required by law shall
accompany each shipment invoice or order to stock. On arrival, the
certificate shall be filed with the project biologist. Protect all plants
from desiccation. “Wiltproof” or another antidesicant shall be applied
only with approval of the project biologist. If plants cannot be planted
immediately upon delivery, properly protect them by covering their
roots with soil or compost, or in another manner acceptable to the
project biologist. Water unplanted plants daily. No plant shall be
bound with rope or wire in a manner that could damage or break the
branches.
B. Cover plants transported on open vehicles with a protective covering
to prevent wind-burn.
C. Container stock, if used, shall be handled by root ball only, not the
trunks, stems or tops.
1.04 PROJECT CONDITIONS:
A. Work Notification: Notify the project biologist at least 5 working days
prior to the installation of plant materials.
B. Protect existing utilities, paving, and other facilities from damage
caused by planting operations.
C. Do not install plant material when ambient temperatures may drop
below 35oF or above 80oF.
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D. Do not install plants when wind velocity exceeds 30 MPH.
E. Confine work to designated areas. Do not disturb existing vegetation
outside project limits and protect all trees, shrubs and ground covers
within project limits not designated to be removed. Do not permit
vehicular traffic or materials storage under or around new or existing
trees.
PART 2 - PRODUCTS
2.01 PLANTS:
A. Plants: Provide plants typical of their species or variety; with normal,
densely developed branches and vigorous, fibrous root systems.
Provide only sound, healthy, vigorous plants free from weeds, defects,
disfiguring knots, sunscald injuries, and abrasions of the bark, plant
diseases, insect eggs, borers, and all forms of infestation. All plants
shall have a fully developed form without voids, open spaces, broken
branches, flush cuts or stubs.
2.02 SOILS:
A. All plants shall be planted in native soils, without soil amendments
with the exception of compost, if recommended by the project
biologist to amend imported topsoil or compacted soils.
2.03 PLANTING FERTILIZERS:
A. Fertilizers shall not be used.
2.04 ARBORIST WOOD CHIP MULCH:
A. Mulches shall be according to the following:
1. Wood Chip Mulch shall be coarse ground wood chips
(approximately 1/2” to 4” along the longest dimension)
derived from the mechanical grinding or shredding of whole
trees or portions of trees. It may contain wood, wood fiber,
roots, bark, branches, and leaves, but may not contain visible
amounts of soil. It shall be free of weeds and weed seeds, and
may not contain more than 1% by weight of manufactured
inert material (plastic, concrete, ceramics, metal, etc.).
Arborist wood chip mulch, when tested, shall meet the
following loose volume gradation:
Percent Passing
Sieve Size Minimum Maximum
2” 95 100
No. 4 0 20
No. 200 0 5
Acceptable substitutes, subject to the project biologist’s
approval, include chipped or shredded woody material,
meeting the above size and inert material requirements,
derived from composting operation screening (“overs”), or
derived from recycling of clean dimensional lumber (e.g.
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pallets or framing lumber) that has passed through a metal
removal process to meet the 1% manufactured inert standard
above.
PART 3 - EXECUTION
3.01 INSPECTIONS:
A. Plant material shall be inspected and approved by the project
biologist at the nursery or on-site prior to installation. Remove all
unsatisfactory material from the site immediately and replace with
acceptable plants.
3.02 INSTALLATION PROCEDURES:
A. Plants brought to the planting site shall be in containers and/or shall
be bare root. Plants shall not be planted during freezing weather or
when the ground is frozen. Plants shall not be planted during
excessively wet conditions. Plants shall not be placed on any day in
which temperatures are forecast to exceed 80 degrees unless the
project biologist approves otherwise. Plants shall not be placed in
areas that are below finished grade.
B. Dates to plant: Planting trees, shrubs, and groundcovers within the
project site shall be performed during the period between October 1
and April 30. Planting at other times shall only by done by written
permission by the project biologist and only if an automatic irrigation
system is available at the site at the time of planting.
C. Plants shall be removed from containers in a manner that prevents
damage to the root system. Containers may require vertical cuts
down the full depth of the container to accommodate removal. All
circling roots shall be loosened to ensure natural directional growth
after planting.
D. Pull aside mulch and excavate circular plant pits with scarified
vertical sides. Provide planting pits at least three times the diameter
of the root system or container. Depth of pit shall accommodate the
entire root system. Scarify the bottom and sides of the pit to a depth
of four inches beyond the depth of the planting pit. If groundwater is
encountered upon excavation of planting pits, the property owner
shall promptly notify the project biologist.
E. Set plant material in the planting pit to proper grade and alignment.
Set plants upright, plumb. Set root crown of plant material at the
finish grade. Backfill the planting pits with native soil. Do not use
frozen or muddy mixtures for backfilling.
F. Spread and arrange roots of bare-rooted plants in their natural
position. Work in backfill soil. Do not mat roots together. Cut all
broken and frayed roots before backfilling with remaining soil.
G. Spread wood chip mulch in a 24” diameter circle, 3” deep, around
each plant, taking care to keep mulch from contacting plant stems.
H. Thoroughly water plants within 24 hours of planting.
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I. Pruning: Prune trees only to remove broken or damaged branches, as
directed by the project biologist. Branches shall be pruned at the
branch collar. Neither stubs nor flush cuts will be acceptable.
3.03 MAINTENANCE AND ESTABLISHMENT:
A. Maintenance shall include regular (at least monthly during the
growing season) weeding to maintain plants free of insects and
disease.
1. Re-set settled plants to proper grade and position and remove
dead material.
2. Correct defective work, as soon as possible, after deficiencies
become apparent and weather and season permit.
3. Between May 15 and October 1, irrigate plantings when soil is
too dry to ensure plant health and vigor. When irrigating,
provide at least 1” of water per week within a 24” diameter
circle around each plant.
3.04 CLEANUP: Perform cleaning during installation of the work and upon
completion of the work. Remove from site all excess materials, debris, and
equipment.
3.05 WARRANTY AND REPLACEMENT:
A. Inspection of plants will be made by the project biologist at the
completion of planting. Warranty plant material to remain alive and
be in healthy, vigorous condition for a period of 1 year after the
project biologist has approved of (in writing) all planting related work.
B. Replace, in accordance with the drawings and specifications, all plants
that are dead or, as determined by the project biologist, are in an
unhealthy condition, and have lost their natural shape due to dead
branches, or other causes due to the property owner’s negligence as
needed to achieve at least 80% survival by Year 2. The cost of such
replacement(s) is at the property owner's expense.
C. Remove and immediately replace all plants, as determined by the
project biologist, to be unsatisfactory during the initial planting
installation.
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3.06 PLANTING DETAIL:
Compliance Monitoring Plan
As-Built
The project biologist will inspect the site during and following planting and prepare
an as-built report to confirm plant quantities and types and show approximate
planting and seeding areas on a site drawing. Representative photos taken at
designated points on the site will also be provided for recording baseline conditions.
Annual Compliance Monitoring
Monitoring will occur for a period of 5 years. The project biologist will monitor the
site at least once during each growing season to record site conditions. Plant health
and cover will be assessed along survey transects or in representative plots to
determine if performance standards have been met during each monitoring year.
Photos will be taken at designated points to compare with baseline conditions. The
project biologist will advise on maintenance throughout the monitoring period.
A monitoring report will be provided to the city in Years 1, 3, and 5. Informal
reporting by email may also occur in Years 2 and 4 if requested by the city.
Contingency Plan
If there is a significant problem with the mitigation achieving its performance
standards, the Applicant and project biologist shall work with the City of Renton to
develop a Contingency Plan. Contingency plans can include, but are not limited to:
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additional plant installation, erosion control, herbicide treatment for invasive plants,
and plant substitutions of type, size, quantity, and location. Such a Contingency Plan
shall be submitted to the city by December 31 of any year when deficiencies are
discovered.
Maintenance Plan
Maintenance tasks will include the following:
At least once every two months in the growing season, cut, pull, grub out, and/or
cover non-native, invasive species, including Himalayan blackberry and Bohemian
knotweed, and other Class “A”, “B”, and “C” noxious weeds identified on the latest
King County noxious weed list. Prioritize weed removal in areas close to the native
plantings while taking care to protect all native plants during weeding.
Between May 15 and October 1, irrigate seeding areas and plantings when soil is too
dry to ensure plant health and vigor. When irrigating, provide at least 1” of water
per week across meadow seeded areas and within a 24” diameter circle around each
installed plant, or across the entire installed planting area. Irrigation is likely to be
needed for up to two years following plant installation.
Replace dead plants as specified by the project biologist.
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Photos
Photo 1. Main gravel fill removal are located in wetland buffer, view south
(February 16, 2016).
Photo 2. Stream buffer and protective fencing, a much smaller amount of gravel fill
extends into the stream buffer (February 16, 2016).
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Photo 3. Himalayan blackberry is a dominant plant in portions of Wetland C and in
the stream buffer (April 14, 2016).
Photo 4. Trees rooted next to the stream at an elevation similar to the streambed
(April 14, 2016).
S 55th StTalbot Rd S102nd Ave SES 50th StS 50th Pl
SE 192nd St
S 53rd Pl
S 52nd St
S 51st St
SE 188th StS 51st Ct
9
8th
P
l
S 99th Pl S98t
h Ave SSE 192nd PlTalbot Pl SSpringbrook Apt AcRdDavis Pl SSE 190th StDavis Ave S101st Ave SE±500 0 500250 Feet
Sources:Parcels: King Co. GIS 2016
Base M ap: ESRI, 2016
Map Date: 9/6/2017, Krippner Consulting, LLC
Figure 1. Neighborhood Detail Map
56.25feet37.5feetWe tland C
802 5 SF
134 34 SF
289 3 SF
±80 0 8040 Feet
Sources: Parcels: King Co. GIS 2016
Stream, Wetland: Krippner Consulting, LLC 2016
Surveyed data: Core Design, 2016
Mapping: 8/31/2017, S. Krippner, Krippner Consulting, LLC
Figure 2. Mitigation Areas
Surveyed Stream
Surveyed Wetland
Mitigation Areas
Gravel Fill Removal Area
Invasive Plant Removal Area
56.25feet37.5feet±80 0 8040 Feet
Sources:Parcels: King Co. GIS 2016, Stream, Wetland: Krippner
Consulting, LLC 2016, Survey data: Core Design, 2016
Mapping: 8/31/2017, S. Krippner, Krippner Consulting, LLC
Figure 3. Planting Areas
Surveyed Stream
Planting Areas
Meadow Seeding
(10,730 sqft)
Tree/Shrub Planting
(10,730 sqft - buffer)
(1,016 sqft - wetland)
Surveyed Wetland
Critical Area Mitigation Plan Gurudwara Singh Sabha of Washington
Appendix A: Mitigation Plan Drawings
Prepared by Core Design