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HomeMy WebLinkAboutRS_Stream_Study_241007_v1Standard Stream Study for City of Renton Application#: PRE22-000119 For the Residence at 5424 NE 10th St, Renton, WA. Parcel #1023059365 Conducted by:Cascade Ecology LLC, 13822 248th Ave SE, Issaquah, WA License # CASCAEL811QD Lead Biologist / Contact:Scott Davis,cascadeecology@gmail.com,206-472-4878 Project Client:Tristan Bull Project Location: 5424 NE 10th St, Renton, WA, 98059 Project Title:Bull Residence Detached Garage Submitted 2/3/2023 Table of Contents 1 Introduction 2 I.Parcel Map Imagery 3 II.The Ordinary High Water Mark 6 III.Stream Classification 6 IV.Site Topography Maps 7 V.100-Year Flood Plain Maps 8 VI.Site Drainage Patterns 8 VII.Stream Cross Section and Top View 9 VIII.Vegetative Cover of Site and Major Trees 10 A.Tree Survey Map 11 B.Tree Survey results 12 IX.Existing Structures / Surfaces on site 14 X.Ecological Function of Site 15 XI.Observed and Reported Wildlife Use 15 XII.Conclusion 16 1 Introduction This stream study is carried out in accordance with RCM 4-8-120. The parcel relevant to this application is Parcel# 10-230-59-365. The parcel is approximately 1.26 acres within the May Creek watershed. The homeowner at 5424 NE 10th St. in Renton, WA, Tristan Bull, wishes to construct an additional structure on the property. Honey Creek, a Non-Fish Seasonal classified stream, runs through the western portion of the parcel, inflowing from a culvert under NE 10th street, then flowing to the northwest, ultimately joining with May Creek within the Honey Creek Greenway natural area. This report outlines the site conditions, stream information, and habitat qualities of the portion of Honey Creek within the parcel, including 100’ up- and down-stream of the affected parcel. The stream study has been carried out by qualified biologist Scott Davis with Cascade Ecology LLC. The site was surveyed repeatedly through 2022 and 2023 to determine site conditions. 2 I. Parcel Map Imagery Image 1: Map indicating parcel 1023059365 highlighted in yellow, showing stream location (“Honey Creek”) on property and +100’ upstream and downstream. 3 Image 2: Aerial photographic image indicating parcel 1023059365 highlighted in yellow 4 Image 3: Parcel map with aerial photographic imagery, including Honey Creek stream and wetland locations according to COR maps. 5 II: The Ordinary High Water Mark (OHWM) The ordinary high water mark was determined on site to be 2’ 2” below the channel minimum bankfull depth. It is noted that within the applicant's parcel, the bank on the eastern shore of the stream is much lower than the opposite bank, therefore the eastern bank was used to determine minimum bankfull depth. The OHMW is marked on site by project biologists with pink survey flagging at 2’ above the OHMW. The OHMW was determined using biological markers on the stems of mature Pacific Willow within the stream bank, as well as side bank scour markings. III: Stream classification According to the City of Renton COR maps, the stream on site, named Honey Creek, is classified as Stream Type NS, or Non-Fish Seasonal. Therefore, it is determined that this project will not have a negative effect on fish habitat or related considerations. Honey Creek is a seasonal stream that runs through the parcel, originating on the parcel in a culvert that runs underneath NE 10th street, flowing to the north through a natural stream corridor, before flowing into May Creek and ultimately flowing into Lake Washington east of Mercer island. Image 4: Stream and wetland locations, with Stream Classification note in top-left corner IV: Site Topography Map 6 Image 5: Contour interval map, indicated 5’ intervals at slopes of 10% or greater, 2’ intervals at slopes of less than 10%. Legend: 7 V: 100-Year Floodplain maps According to City of Renton COR maps, the parcel in question is not located within a 100-year flood plain. VI: Site Drainage Patterns: Existing site drainage patterns are largely driven by site topography, with additional drivers including a barn structure located towards the northwest corner of property, and asphalt-paved driveways located at the southern portion of property. The stream itself flows to the north by northwest. General site drainage patterns are indicated with arrows in the following map: Image 6: Observed and assumed site drainage patterns, indicated on map, based on contours and impervious surface flows 8 VII: Stream Cross Section and Top View 9 VIII: Vegetative Cover of Site and Major Trees The vegetative cover of the site is divided largely into two zones. One zone is the natural conditions within the stream bank of Honey Creek and the associated wetland. The other zone is the “upland zone” adjacent to the stream. The upland zone consists largely of lawn grasses, ornamental fruit trees, and large mature native trees, including Douglas-fir (Pseudotsuga menziesii),Western Red Cedar (Thuja plicata), Western Hemlock (Tsuga heterophylla), and Big Leaf Maple (Acer macrophyllum). The upland zone additionally contains some ornamental fruit trees (Malus and Prunus spp.) within the lawn area. The east-bank of the stream, closest to the project site and main residence, is currently being planted with native plants included Sword Fern (Polystichum munitum), Deer Fern, (Struthiopteris spicant), and Bog Kalmia (Kalmia microphylla).The homeowners have previously restored the stream banks and the upland areas through removal of invasive Himalayan Blackberry shrubs (Rubus armeniacus) and replacement with a variety of native shrubs and trees. The natural stream corridor consists primarily of dense stands of Sitka Willow (Salix sitchensis), Red Osier dogwood (Cornus stolonifera), and Hardhack Spirea (Spiraea douglasii), with larger individual Pacific Willow trees (Salix lasiandra ssp.lucida) . The transition zones are largely occupied by stands of Salmonberry (Rubus spectabilis),Thimbleberry (Rubus nutkanus), as well as mature and senescing Red Alder (Alnus rubra). In addition to the dominant shrubs, there is an herbaceous and grammanoid layer that includes Soft Rush (Juncus effusus), Reed Canarygrass (Phalaris arundinacea), European Watercress (Rorippa nasturtium-aquaticum), Lady Fern (Athryium filix-femina) and Creeping Buttercup (Ranunculus repens). Invasive Yellow-Flag Iris (Iris pseudacorus) was also observed at the inflow of the stream culvert at the southern border of the property. A survey of all trees larger than 6” diameter and a minimum height of 4.5’, within the parcel and 100’ downstream, were recorded for the purpose of this survey. Upstream trees were not measured for this study, because the stream reaches are divided by a culvert and a road (NE 10th st). The upstream area falls within a currently conserved private natural area. The tree survey results are included on the following pages: 10 A: Tree Survey Map: 11 B: Tree Survey Data: Tree Number (on map)Tree Species Diameter at 4.5' (Inches)Height (Feet) 1 Thuja plicata 8.1 33.5 2 Thuja plicata 6.0 3 Thuja plicata 6.6 4 Malus domestica 12.5 5 Malus domestica 9.8 6 Malus domestica 6.3 7 Malus domestica 5.2 8 Salix lasiandra ssp. lucida 6.1 9 Salix lasiandra ssp. lucida 8.1 36.2 10 Salix lasiandra ssp. lucida 9.7 11 Thuja plicata 6.5 12 Salix lasiandra ssp. lucida 7.8 13 Salix lasiandra ssp. lucida 11.0 14 Salix lasiandra ssp. lucida 7.0 15 Alnus rubra 14.4 16 Thuja plicata 12.0 17 Malus domestica 5.5 18 Salix lasiandra ssp. lucida 8.2 19 Salix lasiandra ssp. lucida 11.5 20 Alnus rubra 9.9 21 Prunus sp.11.0 22 Thuja plicata 24.6 63.3 23 Thuja plicata 47.6 99.8 24 Alnus rubra 11.0 45.0 25 Acer macrophyllum 8.1 26 Thuja plicata 44.0 27 Pseudotsuga menziesii 33.0 28 Pseudotsuga menziesii 27.9 29 Picea sitchensis 43.0 116.3 30 Acer macrophyllum 27.0 82.9 31 Tsuga heterophylla 11.8 32 Tsuga heterophylla 12.5 12 33 Tsuga heterophylla 11.0 34 Tsuga heterophylla 38.1 118.6 35 Tsuga heterophylla 10.2 36 Acer macrophyllum 17.1 37 Tsuga heterophylla 20.9 38 Alnus rubra 9.6 39 Pseudotsuga menziesii 28.8 40 Picea sitchensis 13.7 41 Alnus rubra 13.3 42 Pseudotsuga menziesii 21.5 43 Acer macrophyllum 23.7 79.4 44 Thuja plicata 29.0 92.6 13 IX: Existing Structures on Site The project area and parcel consist of a primary driveway (paved), an accessory driveway (paved), and a barn-type structure, in addition to the primary home. The additional roads and structures are presented relative to the stream and wetland areas in the following map: 14 X: Ecological Function of Site The stream on site currently performs a number of ecological functions, such as storm water management, storm and ground water filtration, appropriate habitat for native plant communities, and sediment and nutrient dispersal and cycling for the local watershed. The stream corridor provides a visual and auditory barrier for the neighborhood, and locally tempers wind speeds and temperature. Additionally, the stream corridor provides the aesthetic values of a natural, wild setting. The main limitation to the ecological services provided by the stream is the upstream culvert, which functionally divides the stream corridor on either side of NE 10th st, and significantly reduces connectivity of upstream habitat to the site. The current project proposed to place a structure and associated foundations within the buffer of the stream corridor. Normally, this could alter or degrade some functions of the stream, particularly those related to stormwater management. However, in this case the proposed structure is designed to be in place of existing impervious surface (asphalt driveway) and some area of ornamental lawn grass. The replacement of the area of ornamental lawn grass represents a slight increase in impervious surface area; it is not expected to significantly affect the creek, water and sediment flows, or other ecological functions of the site. In addition to these ecological functions, the stream and riparian area serve as habitat for wildlife species, which will be detailed in the following section. XI: Observed and Reported Wildlife Use The only observed wildlife use during survey periods was visitation by various songbird species and woodpeckers, such as the Black Capped Chickadee(Pocile attricapillus), the American Robin (Turdus migratorius), and the Hairy Woodpecker (Picoides villosus). It can also be presumed that the area is visited by raptors such as Crows, Ravens (Corvus spp.), and Hawks (Buteo spp.), as well as mammal species such as Black Tailed Deer (Odocoileus hemiunus columbianus), Elk (Cervus canadensis), Coyote (Canis latrans), and Black Bear (Ursus americanus).In the northwest portion of the site,a Muskrat (Ondotra zibethicus) den was observed, which appeared to be actively used and maintained. The proposed construction activities are not expected to affect the wildlife quality of the area, as no trees or native vegetation will be removed or affected. To ensure the integrity of existing trees, all native plants and trees that are within the construction zone or ingress egress thereto, should be protected. 15 XII: Conclusion The conclusion of the stream study is that the proposed project, if carried out in accordance with an appropriate plan and local regulations, should not have any significant disturbance to Honey creek, the stream corridor, or the associated wetland. The placement of the proposed structure should not disturb any existing native trees or vegetation, and should contribute minimally to total impervious surface area or local stormwater runoff conditions. Furthermore, no wetland or sensitive areas should be disturbed. The current mitigation efforts by the homeowners to increase native plant cover and diversity along the stream bank should improve the quality of the stream corridor and mitigate any increase or change in surface or groundwater flow into the stream corridor. 16