18-102990j� 5309 Shilshole Avenue NW www.esassoc.com
ESA ■ Suite 200
Seattle, WA 98107
206.789.9658 phone
206.789.9684 fax
memorandum
date March 25, 2015
to Kenneth Canfield, Lakehaven Utility District
from Claire Hoffman and, Michael Muscari
subject Wetland Delineation on parcel 2921049088
Introduction
Environmental Science Associates (ESA) was contracted by the Lakehaven Utility District (LUD) to
conducte a wetland reconnaissance and partial delineation of the property (Tax Parcel 2921049088) on
the corner of Pacific Highway South and South 359th Street in Federal Way (the property). The LUD is
considering purchasing this property for a potential relocation of the existing pump station on the
adjacent property.
Background Information
ESA performed a review of existing information regarding wetlands and streams. Sources of
information included current aerial photographs, City of Federal Way maps, and National Wetland
Inventory (NWI) data. The majority of the property is mapped by NWI as palustrine forested wetland,
with the exception of the eastern edge (USFWS, 2015). The City of Federal Way Critical Area Map
shows the entire property as a wetland with a stream on the western edge (Federal Way, 2012). The
Spring Valley Open Space lies to the north and south of the property and a fish bearing tributary to
Hylebos Creek runs north/south on the adjacent property to the east (Federal Way, 2008).
Wetland Delineation and Reconnaissance
On February 10, 2015 Claire Hoffman and Michael Muscari from ESA conducted a wetland delineation
and reconnaissance of the property. During this site visit, ESA staff and Ken Canfield (LUD) walked
the perimeter of the property as well as a diagonal path through the center of the property to observe and
assess wetland conditions. A second site visit was conducted on February 13, 2015 by Michael Muscari
and Scott Olmsted to complete data collection. The wetland was identified and delineated based on
conditions at the time of the field visit by applying the wetland determination method described in the
Regional Supplement (Western Mountains, Valleys, and Coast) to the Corps of Engineers 1987 Wetland
Delineation Manual Corps (Corps, 2010). A Trimble Geo-XT GPS unit was used to record the location
of the eastern wetland boundary, the remaining boundary was estimated. The wetland was classified
according to the Washington State Department of Ecology's (Ecology) Wetland Rating System for
Western Washington (Hruby, 2014) and City of Federal Way Revised Code (FWRC 19.175.020).
Several data plots were established along the eastern property boundary in order to delineate the wetland
boundary. Wetland indicators were present for hydrology, vegetation, and soils at each plot determined
to be within the wetland boundary. Soils were saturated from the surface to a depth of at least 16 inches.
Dominant vegetation consisted of wetland tolerant species. Soils exhibited hydric soil characteristics
including redox dark surface and depleted matrix.
The wetland on the property is part of a larger wetland complex (>30 acres), which includes a tributary
to Hylebos Creek and extends from approximately South 359th Street to just north of South 373rd Street
between Pacific Highway South and I-5. Just north of South 373rd Street, the tributary joins West
Hylebos Creek. Figure 1 shows the extent of the wetland on the subject property. The wetland covers
the majority of the property with a narrow section on the eastern edge of uplands along the paved
driveway to the existing pump station. The wetland on the property is forested with many large trees
including Western red cedar, Douglas fir, red alder, and vine maple. The dominant shrub is
salmonberry, which provides moderately dense cover. Skunk cabbage and other native herbaceous
plants are common throughout the site. The eastern edge of the wetland is emergent wetland as the
wetland extends out of the forest into the driveway easement. This area is dominated by various grass
species, including reed canary grass and soft rush.
Shallow groundwater appears to be the primary source of hydrology to the wetland. There are also at least
three culverts draining into the subject property. Two carry water under South 3596' Street from the wetland to the
north; one near the one-third point (from the intersection of Pacific Highway and South 359t' Street) of the north
property boundary, a second near the northwest corner of the property, and a third under Pacific Highway South
near the mid -point of the west property boundary. At the time of the site visit the culverts had low flow. The
water emerging from the northwestern culvert and the northerly culvert appear to merge and cross as a stream
through the center of the property. A constructed ditch (likely decades old) runs approximately the length
of the property near the southern boundary and is likely connected to the aforementioned western
culvert.
Under FWRC 19.175.020, this wetland would likely be considered a Category I because it has high
function for wildlife habitat, water quality improvement, and hydrologic support. Habitat complexity is
apparent because the wetland has three or more wetland classes, one of which is open water. Open water
and emergent wetland classes are visible on aerial photography to the south of the subject property.
Although these portions of the wetland are not on the subject property they are part of the wetland unit
and thus considered in the rating. Structural complexity in the vegetation community also provides a
high level of wildlife habitat functions. Ecology's rating system also categorizes it as a Category I
wetland. Federal Way requires a 200-foot buffer around Category I wetlands (FWRC 19.175.020).
2
References
Corps (U.S. Army Corps of Engineers). 2010. Regional Supplement to the Corps of Engineers
Wetland Delineation Manual: Western Mountains, Valleys, and Coast Region. Version 2.
Wetlands Regulatory Assistance Program. May 2010. ERDC/EL TR-10-3.
http://www.usace.army;mil/CECW/Documents/cecwo/reg/west_mt finalsupp.pdf.
Federal Way. 2008. Current Land Use Map. Accessed March 24, 2015. Available at
http://www.cityoffederalway.com/DocumentCenter/HomeNiew/457.
Federal Way. 2012. Critical Areas Map. Accessed March 24, 2015. Available at http://wa-
federalway.civicplus.com/DocumentCenter/HomeNiew/460.
Hruby, T. 2014. Washington State Wetland Rating System for Western Washington — 2014 Update.
Ecology publication number 14-06-029. Olympia, WA.
USFWS. 2015. National Wetlands Inventory Wetland Mapper. Accessed March 24, 2015. Updated
May 1, 2014. Available at: http://www.fws.gov/wetlands/Data/Mapper.html
Photographs
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SOURCE: ESA 2015, OSM 2014, King County 2014, ESRI
2013
Lakehaven Pumpstation. 206061.14
Figure 1
Lakehaven Utility District Pump
Station Investigation Site