HomeMy WebLinkAboutWetland Mitigation 821182003
Revised Wetland Buffer Mitigation Plan
for
Ernest & N aney Slagle.,
Port Ludlow, Jefferson County, Washington
Case #: BLDOO-00036/BLD07-00398
Submitted:
August 19,2008
RECEi'llF:O
. OCT 0 9 2008
Revised:
October 8, 2008
JHfEHSONCOUNTY DCD
Prepared for;;
w~+-\J\~PROVED
ro I itfl. ~I(/t"l PLAN
Lou Slagle
2203. Beaver V alley Road
Port Ludlow, W A 98365
OCT 2 2 2008
Prepared by:
J-WSP
WSP Environment & Energy
Ecosystem Science & Natural Resources
Management Services
2324 Eastlake Ave. East, Suite 505
Seattle, W A 98102
DISCLAIMER
WSP Environment & Energy has prepared this critical areas assessment and mitigation report for
use by Mr. Lou Slagle. The results and conclusions are based upon information provided by
Olympic Wetland Resources, Inc. (April, 2000) and public domain information (e.g. U.S.
Geological Survey. 7.5' topographic quadrangle maps, Natural Resources Conservation Service
Soil Surveys, and air photographs from various sources), as well as on-site reconnaissance, data
collection, and analyses by standard methods. This report represents the best professional
judgment ofWSP Environment & Energy.
Lyndon C. Lee, Ph.D., PWS
Principal Ecologist & Vice President .
Ecosystem Science. & Natural Resources Management Services
WSP Environment & Energy .
10/8/08
Date
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OCT Q 9 2008
I. INTRODUCTION
. IEtlEHSUN COUNTY DeD
WSP Environment & Energy (WSP) was retained by Ernest (Lou) Slagl~ l>. assIst wim' 'the
wetland buffer mitigation plan and storm water dispersion portions of Jefferson County
(hereafter "County") permits (Manufactured/Mobile Home Installation Permit and Building
Permit) associated with replacement of a manufactured home on his property (Case #: BLDOO-
00036).
A. Project Site
The Slagle property is located at 2203 Beaver Valley Rd, Port Ludlow,W A 98365 (Jefferson
County Tax Parcel #821182003) (Figure 1). The project site abuts Ludlow Creek and its adjacent
wetland. The location of the new home site lies outside of the stream buffer setback area (100
ft), which is itself subsumed within the creek's adjacent wetland. However, the project lies in
close proximity of the wetlands adjacent to Ludlow Creek (Figure 2, Olympic Resourc~s
(2000)). According to the Jefferson County Manufactured/Mobile Home Installation permit #
BLDOO-00036 that was received in January 2000, the County has required a setback of 75-feet
from the delineated wetland edge, with the exception of the existing slab footprint for the
proposed manufactured home, which is allowed to have a setback of 67 feet. The County has
also required that this 75ft and 67 ft wide area shall be permanently maintained as a wetland
buffer. The County has further stipulated that the buffer will be planted with native trees and
shrubs as mitigation to offset any potential impacts to the wetland from the Slagle project.
B. Project History
A wetland delineation report dated April 2000 was prepared by Olympic Wetland Resources, Inc
for the Slagle property. On August 2, 2008, Dr. Lyndon Lee of WSP completed a
reconnaissance of the Slagle property and confirmed the general accuracy of Olympic Wetland
Resources 2000 delineation. In addition, Dr. Lee reviewed County requirements for the buffer
and discussed an approach for designing and planting the buffer area with the Slagle's. The
following mitigation plan was designed to follow condition requirements set forth by Jefferson
County regarding permits associated with case #: BLDOO-00036 and, to the extent possible, be
compatible with the Slagle family's goals for use of the buffer area.
II. PROPOSED MITIGATION
A. Mitigation Site Location and Geometry
The proposed mitigation site (buffer area) will be located on the Slagle property, generally west
and north of the new house structure (Figures 1 and 2). Proposed management of the buffer will
include installation of a diverse native plant community east/north of the wetland boundary and
within the designat~d buffer area. Approximately 0.78 acres will be planted in a 67-75 foot wide
band along the wetland boundary (Figure 2, not drawn to scale).
1
Rr~~if'TED
DCT (1 9 21lU8
B. Existing Conditions at the Mitigation Site JffffRSON COUNTY OeD
The.proposed wetland buffer mitigation area consists of cleared land dominated by bare mineral
soil and native and non-native grasses. Modal soils are mostly fill material. Soils on adjacent
lands are mapped by the NRCS as Everett gravelly sandy loam and McMurray and Mukilteo
Peat.
C. Proposed Mitigation
A setback of 75 ft and 67 feet around the edge of the existing slab footprint for the new home
will be created along the wetland edge on the Slagle property. This area will be permanently
maintained as a vegetated buffer. Consistent with County requirements, the eastern perimeter of
the buffer will be delineated by a plant (and prominent) line of native trees. In addition, an array
of native trees, shrubs, and grasses will be planted within the buffer to increase hydrologic,
biogeochemical, plant community, and faunal support!habitat functions of the buffer area.. The
species and quantities of piants selected for planting within the buffer (planting take-offs) are
offered in Table 1. Native species which provide fruits may also provide a foraging source for
wildlife. In addition, consistent with the Slagle family's goals, many of the species in Table 1
produce edible fruits (e.g. red elderberries, Indian-plum, salal, .red huckleberries, evergreen
huckleberries, black and red raspberry, Pacific crab apples, and thimbleberries).
Acquisition of planting materials should align with Table 1 to the greatest extent possible. As
with all native plantings, species composition offered in Table 1 may need to be slightly adjusted
depending on availability of plants. Nevertheless, the total numbers of trees (166) and shrubs
(195) specified for the area will be met. If any of these species are not available, a similar
number and type of native plant will be obtained. However, substitution of species from Table 1
must be approved by Jefferson County. Specifically, tree species that are candidates for
sub~titution and which are not listed in Table 1 include: Oregon white oak (Quercusgarryana),
Sitka spruce (Picea sitchensis), shore pine (Pinus contorta), and Pacific madrone (Arbutus
menziesii). Shrub species that may be substituted are: Ocean spray (Holodiscus discolor),
Pacific ninebark (Physocarpus capitus), red flowering currant (Ribes sanguineum), and
snowberry (Symphocarpos albus).
D. Construction Sequencing
Planting will be implemented by the Slagle family. . A qualified wetland biologist will be
consulted in the field to determine planting layout, to explain appropriate planting techniques to
attain maximum plant survival, and to assist in acquisition of healthy planting material. Plants
should be installed during the interval mid October to late November, 2008, when conditions are
optimal for plant survival. If necessary, infill planting will occur in Spring 2009, before April
15th. Before planting site preparation or any ground-breaking activity begin~ (before installation
of sediment fence), the wetland buffer shall be staked. The' County must review and approve the
wetland buffer staking prior to installation of the sediment fence. The applicant shall call the
Jefferson County wetland biologist (360-379-4450) after the wetland buffer has been staked and,
at least 72 hours prior to installing the sediment fence.
2
"
The buffer site will be prepared for planting by removing all debris (metal roofing, lumber piles,
etc.) and by discing the area to break up the existing turf and loft the soil. Beyond the initial
discing to prepare the planting area, no filling, grading, clearing, or other alteration of the
wetland or its buffer is necessary or allowed.
Prior to any site preparation activity (e.g., discing the buffer for site preparation), a sediment
fence shall be installed at the wetland edge (Figure 3). The minimum height of the top of
sediment fence shl~ll be 2 feet and the maximum height shall be 2.5 feet above the original
ground surface. The sediment fence shall be buried in a trench to a minimum depth of 5 inches
below the ground surface. The trench shall be .backfilled with soil and these soils shall be
compacted over the buried portion of the sediment fence, such that no water flow Can pass
beneath the fence. Any damage to the sediment fence shall be repaired immediately. Sediment
deposits on the up-gradient side of the fence shall either be removed when the deposit reaches
approximately one-third the height of the sediment fence, or a second sediment fence shall be
installed.
After discing the buffer area which will be planted, trees will be installed at approximately. 15
feet on-center (o.c.) spacing throughout the buffer. Shrubs will be planted in masses or clumps
of three to fifteen plants at 3 approximately feet o.c. spacing. Approximately 12 - 15 feet of
space will be left between the clumps to maneuver equipment (e.g. weed whackers) for routine
weed control. Trees and shrubs will be installed following standard methods as detailed in
Figure 4. A native grass seed mixture (50%/50% mix of Festuca rubra and Poa pratensis) will
be hand applied throughout the buffer to establish ground cover. Seeded soil will be covered
with a hand applied 4" - 6" lift of sterile (weed-free) straw.
Following plant installation and within 30 days, monitoring will commence with submission of a
baseline monitoring report as described in Section III.B of this report. Wetland buffer areas shall
be maintained in their natural condition, however, minor pruning, infrequent mowing or
alteration of vegetation may be permitted as long as the function and character of the buffer are
not diminished.
E. Signage
During construction, wetland buffer perimeters . shall be marked with temporary signs at an
interval of one per parcel or every one hundred feet, whichever is less. Signs shall contain the
following statement: "Wetland Buffer - Do Not Remove or Alter Existing Vegetation." As
explained above, along the generally eastern and northern (upland) perimeter of the wetland
buffer,. a permanent physical separation along the upland boundary of the wetland buffer area.
shall be marked by a prominent line of trees and shrubs.
RECEf\TE,D
OCT 0 9 2008
3
JHfERSON CUU~1't DCa
III. PROJECT TARGETS AND MONITORING PLAN
A. Project Targets, Project Standards and Success Criteria
The following primary targets will be used to measure success of the mitigation project:
Tan!et #1: " Establish a native plant community suited tothe current conditions of the
mitigation site.
Project Standards:
a. Remove non-native species within the wetland buffer.
b. Plant native trees and shrubs suited to micro-site conditions.
Success Criteria:
a. Within five years, there is an established native plant community, consisting of a
minimum of three strata of species including trees shrubs, and grasses.
b. Plant survival after 5 years is no less than 85%.
c. Canopy cover of the all canopy layers of the plant community is >85% after 5 years.
d. Non-native plants make up less than 5 % of any canopy layer (tree, shrub, herb).
Contingency Measures/Adaptive Management:
,a. Supplement planting as necessary to develop a plant community with three strata.
b. On an annual basis, replace plants that do not survive to ensure miniri1U~ of 85%
survival after five years.
c. Install an irrigation'system as necessary.
d. Control weeds through mowing, hand removal, weed-eater, or as a last resort, chemical
controL
Tan!et #2:
Improve on-site habitat for native faunal species.
lRECElVlED
OCt rc 9 2U08
Project Standards:
a. Remove non-native species from the wetland buffer.
b. Plant native trees and shrubs suited to micro-site conditions.
JH{a~L'~; \]\\\\"\1 DW
Success Criteria:
a. Within five years there is an established native plant community, consisting of a
minimum of three strata of species including trees and shrubs.
b. Canopy cover of the all canopy layers of the native plant community is greater than 85%
after 5 years.
Contingency Measures/ Adaptive Management:
a. As stated in Target 1, install supplemental plants as necessary to increase development
of canopy cover. Select alternate species ifhigh mortality rate occurs for any species.
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B. Monitoring
Upon completion of the construction and plant installation, baseline conditions will be
documented. Permanent photo-monitoring points will be established. A monitoring report will
be prepared by a qualified biologist and shall include photos, an as-built map documenting
installed plant species and densities, and a narrative documenting baseline conditions. This
report shall be submitted to Jefferson County within 30 days of plant installation for review and
approval and will be kept on file with the County.
The mitigation site will be monitored over a five (5) year period to ensure the plant community is
being restored successfully. In all years, plant survival rates will be recorded, and a monitoring
report with photo-documentation will be produced. The monitoring reports will be prepared and
submitted to Jefferson County by October 31 of each monitoring year. Each report will identify
whether adaptive management and corrective actions are needed to meet project targets.
c. Adaptive Management
Adaptive management will be focused on (1) weeding to control non-native plants within the
buffer, and (2) annual replacement of plants which suffer mortality during the monitoring period
to ensure 85 % survival by the end of Year 5. Specifically:
1. Weed and invasive plant removal will occur, as necessary, but -at least two times per year
during the growing season (e.g., April and July). Control of weeds will be accomplished though
a combination of mowing, weed whacking, and as a last resort, application of approved
herbicides
2. Plant survival for Year 1 should be 100% for the number of plants listed in Table 1. In
monitoring years 2-5, survival should be a minimum of 85%. If in any given monitoring year, it
is found that the survival rate is less than 85% (or if less than 100% in Year 1), the affected
species shall be replanted. If necessary, alternative species and/or alternative site locations or
plant densities may be recommended. As indicated above, substitution of plant species must be
approved by Jefferson County.
3. A temporary irrigation system can and will be installed if necessary.
RECEI'T1K,O
OCT 0 9 2DDI ,
IV. STORMW ATER MANAGEMENT SYSTEM
A. Roof Runoff
JEffERSON COUNlY UCU
Stormwater concerns from the proposed project are limited to downspouts which convey roof
runoff to the ground around the home. The flow from gutters to downspouts will be maintained
to provide sufficient stormwater dispersion. At each downspout discharge point, roof runoff
water will be directed to subsurface dispersion pipes that will be installed adjacent to the home,
at least 650 feet from the wetland edge. The dispersion pipes (4" diameter) will be installed in a
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washed gravel-lined trench that is approximately 2 feet wide by 1.5 foot deep (Figure 5) (WA
DOE 2005). A maximum of 700 square feet of roof area may drain to each dispersion trench.
B. Buffer Restoration Stormwater Management
A sediment fence will be installed along the wetland edge prior to preparation of the site for
planting and will be maintained until grass cover is established (See Section n.D.). In addition,
consistent with discussions offered above regarding planting, the buffer area will be broadcast
seeded with a native mix and then covered with sterile straw.
Y. REFERENCES CITED
Olympic Wetland Resources, Inc. April 2000. Lou Slagle Wetland Delineation. Prepared for
Mr. Lou Slagle.
Washington Department of Ecology (WA DOE). 2005. Stormwater Management in Western
W ashington, Volume III. Hydrologic Analysis and Flow Control Design/BMPs.
R1F r" ~'f\IED
OCT 0 9200S
JEffERSON COUNTY OeD
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RECEIVE 10)
Table 1.
ff,
ocr 092008
Take-offs for wetland buffer planting at the Slagle. property, Port Ludlow,
Je erson County, Washin2ton. . ".r
Wetland Buffer Plantin2 Take-Offs (0.78 acres) "LilLi
Species On Center Spacing Material Unit
Scientific Name Common Name (ft) Type Total
Trees (200 stems/acre)
. 1 gallon or
Thuja plicata Western red cedar 15 bare root 30
Pseudotsuga menziesii Douglas-fir 15 1 gallon or 26
bare root
Tsuga Heterophylla Western hemlock 15 1 gallon or 10
bare root
Malus fusca Pacific crab apple 15 1 gallon or 40
bare root
Acer circinatum Vine maple 15 1 gallon or 20
bare root
Acer macrophyllum Big-leaf maple 15 1 gallon or 10
bare root
Populus tremuloides Aspen 15 1 gallon or 10
bare root
Prunus emarginata Bitter cherry 15 1 gallon or 10
.
bare root
Rhamnus purshiana Cascara 15 1 gallon or 10
bare root
Total trees 166
Shrubs (250plants/acre)
Amelanchier alnifolia Saskatoon 3 (in clusters) 1 gallon 20
Gaultheria shallon Salal 3 (in clusters) 1 gallon 15
Oemlaria cerasiformis Indian plum 3 (in clusters) 1 gallon 15
Sambucus racemosa Red elderberry 3 (in clusters) 1 gallon 15
Rosa nootkana Nootka rose 3 (in clusters) 1 gallon 10
Rosa pisocarpa Swamp rose 3 (in clusters) 1 gallon 10
Vaccinium parviflorium Red huckleberrry 3 (in clusters) 1 gallon 20
Vaccinium ovatum Evergreen 3 (in clusters) 1 gallon 20
huckleberry
Comus sericea Red osier dogwood 3 (in clusters) 1 gallon 10
Rubus leucodermis Black raspberry 3 (in clusters) 1 gallon 20
Rubus idaeus Red raspberry 3 (in clusters) 1 gallon 20
Rubus parviflorus Thimbleberry 3 (in clusters) 1 gallon 20
total shrubs 195
Grasses
Poa pratensis Kentucky bluegrass seed mix
F estuca rubra Creeping red fescue seed mix
Deschampsia cespitosa Tufted hairgrass 30 1 gallon 38
SUN COUNTY OeD
7
Figure 1. Location of Slagle property near Port Ludlow, Washington.
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Figure 2. Extent of waters and wetlands and their buffers on the Slagle
property completed by Olympic Wetland Resources in 2000.
Note: Fi~re was not drawn to scale.
JRECEJr\VED
OCT 0 9 200S
JEfffRSUN CUUNIY DCD
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STANDARD SEDIMENT FENCE
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Figure 3. Sediment fence installation specifications.
RECEfVlE1D
OCT 0 9 2008
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TREE PLANTING DETAJL
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Figure 4. Tree planting specifications. Shrubs should be planted similarly.
RECEJ[\VED
OCT 0 [; 2008
JEffERSON COUNTY Deu
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Figure 5. Specifications for installation of downspout
dispersion trench (W A DOE 2005).
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