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(20) Standard Stream Study – Kennydale Gateway
Vulcan Real Estate
Renton, Washington
Stream Assessment Narrative
May Creek is identified as a Shoreline of the State. It is not a Shoreline of Statewide
Significance, however. The shoreline jurisdiction zone is identified by the City of Renton’s
Comprehensive Plan as “Shoreline: High-Intensity’ (City of Renton 2015). This zone is
measured landward from May Creek’s OHWM. In addition to the shoreline management zone,
May Creek also has a 100-foot vegetation conservation buffer.
No reach of May Creek flows onto the Site. Rather, the parcel it flows through is identified as
May Creek Trail Park, a City-owned property. This parcel is mostly forested and shows signs of
restoration and enhancement plantings. A soft surface trail (May Creek Trail) extends across
the northern portion of the park, intersecting Lake Washington Boulevard near the Site’s
southwestern corner. The trail forms a loop at the park’s eastern end around a City-mapped
wetland. The trail does not cross May Creek or continue under I-405 to more City-owned open
space associated with May Creek. Vegetation associated with the riparian corridor includes
beaked hazelnut (Corylus cornuta), red alder (Alnus rubra), black cottonwood (Populus
balsamifera), bigleaf maple (Acer macrophyllum), twinberry honeysuckle (Lonicera involucrata),
salmonberry (Rubus spectabilis), indian plum (Oemleria cerasiformis), prostrate knotweed
(Polygonum aviculare), creeping buttercup (Ranunculus repens), and fringed willowherb
(Epilobium ciliatum). Further, May Creek is used by numerous fish species, including coho
(Oncorhynchus kisutch), fall chinook (Oncorhynchus tshawytscha), winter steelhead
(Oncorhynchus mykiss), resident coastal cutthroat (Oncorhynchus clarki), and sockeye
(Oncorhynchus nerka).
A portion of the Residential Development will occur within the 200-foot shoreline zone of May
Creek. The Site’s area of impact to the shoreline zone will be approximately 55,854 sf. The
shoreline zone is identified as a Shoreline High-Intensity Overlay District. The objective of this
overlay district is to allow large-scale office, commercial, multi-family residential, and public
service uses while protecting existing ecological functions or restoring ecological functions of
areas that have been previously degraded (City of Renton 2015). Management policies suggest
that water-oriented development activities be considered. However, the City recognizes that
properties within this overlay district are likely to have existing developments that are not water-
oriented. Therefore, non-water-oriented development should be permitted where it does not
conflict with or limit opportunities for water-oriented uses, or where direct access to the
shoreline is not currently provided. Public access is a priority, as are ecological restoration and
aesthetics.
It will not be possible to completely avoid impacts to the shoreline on the Site. The portion of
the site within shoreline jurisdiction is approximately 84 percent developed with impervious
surfaces and buildings. The proposed development plan will increase the area of impervious
surfaces within shoreline jurisdiction by approximately 5 percent. However, stormwater
collected on the proposed impervious surfaces within shoreline jurisdiction will be cleansed
using enhanced stormwater treatment technologies before release into the existing stormwater
detention pond. It is anticipated that the use of enhanced stormwater treatment technologies
will substantially improve the quality of water discharged. No untreated stormwater will be
released into of the May Creek shoreline zone south of the Site.
No Net Loss. The Site is currently developed with impervious surfaces comprising nearly 82
percent of the Site’s total area. Stormwater is currently collected onsite and discharged to a
stormwater treatment pond located at the Site’s southwestern corner. The proposed project will
include required landscaping and open space. Based on the current development plans, the
amount of impervious surfaces will be reduced from 82 percent under current conditions to
approximately 76 percent of the developed condition. In addition, enhanced stormwater
treatment will be provided to further improve the removal of toxic metals and organic
compounds, as well as sediments, trash, and other debris. The proposed reduction of the
vegetation conservation buffer where it currently extends onto the Site will not cause a net loss
of ecological function.
References
City of Renton. 2015. City of Renton Comprehensive Plan.
Figures
Figure 1. Existing Conditions
Figure 2. Proposed Site Development
Figure 3. Core Design Overall Site Plan
Figure 4. Core Design Utility Plan
Figure 5. Core Design Utility Plan
Figure 6. Core Design Utility Plan
Figure 7. Core Design Grading Plan
Figure 8. Core Design Grading Plan
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