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HomeMy WebLinkAboutRS_Critical_Areas_Technical_Memo_180320_v1 11241 Willows Road, NE, Suite 200, Redmond, WA 98052  Phone (425) 882-4446 Fax (425) 827-9577 otak.com Technical Memorandum To: Chris Erickson, King County Department of Natural Resources and Parks From: Stephanie Modjeski, Wetland Scientist Kevin O’Brien, Senior Ecologist Copies: Bob Doherty, File Date: 2/7/2018 Subject: May Creek and Ripley Lane Critical Areas Update Project No.: 32499.E Introduction King County (County) Department of Natural Resources and Parks (DNRP) is proposing the May Creek and Ripley Lane Trestle Rehabilitation Project. The project intends to repair and retrofit two trestle bridges located in the City of Renton to the east of Lake Washington. The trestles are currently used as recreational pedestrian bridges and are planned to become part of the multi-use Eastside Rail Corridor Regional (ERC) Trail in Renton. The trestles are deteriorated and have defects and are in need of repairs to provide continuous use of the trail system. In addition to repairs and rehabilitation of existing components of the trestle bridges, existing timber railroad ties and steel railroad tracks will be removed, and new decking and railing will be installed. The County has requested a site inspection to verify the presence of critical areas on the subject property. Otak, Inc. Critical areas have been previously identified in the project area in the Ecosystem Resources Inventory— Eastside Rail Corridor Regional Trail Master Plan Project prepared for King County by Parametrix, dated May 12, 2015. Otak biologists conducted a site visit on November 14, 2017 to verify the presence of critical areas as documented in the 2015 ERC report. Critical areas reviewed include wetlands, streams, and habitat conservation areas as regulated by Renton Municipal Code (RMC) Chapter 4-3-050 (Critical Areas Regulations). The project is located in the City of Renton, King County, Washington. The May Creek trestle is located approximately 300 feet north of N. 41st Street, west of Lake Washington Boulevard. The Ripley Lane trestle is located west of and adjacent to Ripley Lane N., west of Interstate 405. The project is located in Sections 32 and 29, Township 24 North, Range 05 East of the Public Land Survey System. Page 2 of 4 Summary of 2015 Report The 2015 report from Parametrix describes one wetland (WR11) and three streams (May Creek, SR6, and SR7) located within the project area. Wetland WR11 is located below the Ripley Lane trestle and extends from the middle of the trestle length to the southern end of the bridge. WR11 is a depressional/riverine wetland with a palustrine forested Cowardin habitat class. Wetlands were not rated in the 2015 report. Stream SR6 is a perennial stream that flows north, parallel to the Ripley Lane trestle and discharges to stream SR7. Stream SR7 is a perennial stream that emanates from a culvert on the east side of Ripley Lane North and flows west under the trestle. SR6 and SR7 are tributaries to Lake Washington and were not typed per the 2015 report. May Creek is a perennial stream that flows west under the May Creek trestle. May Creek is classified as a Shoreline (Class 1) per the City. Methods Otak biologists conducted a site survey on November 14, 2017 to confirm the presence or absence of critical areas within the project area. Wetland boundaries were determined using methodology derived from the Regional Supplement to the Corps of Engineers Wetland Delineation Manual: Western Mountains, Valleys, and Coast Region (USACE, 2010) and the Corps of Engineers Wetland Delineation Manual (Environmental Laboratory 1987). Vegetation communities, soil profiles and site hydrology were assessed to identify and confirm wetland boundaries. The boundaries of streams within the project area were determined using methodology from Determining the Ordinary High Water Mark for Shoreline Management Act Compliance in Washington State (Ecology 2016). Identification of OHWM was based on field indicators and stream physical characteristics such as: line of vegetation, drift logs, erosional or depositional features, changes in sediment and vegetation characteristics, wracking, erosion/scour and silt deposits. The following resources were also reviewed for additional background information, accessed on November 10, 2017:  King County iMap (http://gismaps.kingcounty.gov/iMap/)  National Wetlands Inventory (https://www.fws.gov/wetlands/data/mapper.HTML)  United States Department of Agriculture – National Resource Conservation Service (USDA-NRCS) Web Soil Survey (https://websoilsurvey.sc.egov.usda.gov/App/HomePage.htm)  Washington Department of Fish and Wildlife Priority Habitats and Species (PHS) on the Web (http://wdfw.wa.gov/mapping/phs/)  Washington State Department of Natural Resources (DNR) Forest Practices Application Mapping Tool (https://fortress.wa.gov/dnr/protectiongis/fpamt/default.aspx) Page 3 of 4  City of Renton mapping data Findings Wetlands One wetland (WR11) is located within the project area below the Ripley Lane trestle. WR11 extends from the middle of the length of the trestle to the southern end of the bridge. Wetland boundaries remained similar to the original delineations in the 2015 report. In the 2015 report, WR11 is classified as palustrine forested (PFO) under the Cowardin Classification System (Cowardin 1979) and as riverine-depressional under the hydrogeomorphic (HGM) classification system (Brinson 1993). The wetland remains a riverine-depressional wetland but now has a palustrine emergent (PEM) habitat component as well as PFO habitat. Hydrology within the wetland is driven by a flow-through stream (Stream SR6) as well as shallow groundwater. The wetland vegetative community is consistent with the 2015 report, composed of red alder (Alnus rubra) as the primary tree species and horsetail (Equisetum spp) and reed canary grass (Phalaris arundinacea) as the primary emergent species. Streams and Habitat Conservation Areas The OHWM boundaries, type, and characteristics of all identified watercourses are consistent with the 2015 report. Riparian vegetation included red alder, black cottonwood (Populus trichocarpa), horsetail, reed canary grass, and Himalayan blackberry (Rubus armeniacus). Streams SR6 and SR7 are located within the Ripley Lane trestle project area. SR6 flows north, parallel to the Ripley Lane trestle and converges with SR7. The stream is mildly incised and rock armoring is present along portions of the banks, although stream banks overall are relatively stable. SR6 is not mapped by Washington Department of Natural Resources (DNR), and is mapped as a perennial, non-fish bearing stream (Type Np) by the City of Renton. SR 6 has a standard buffer of 75 feet per City of Renton Municipal Code (RMC) 4-3-050. Stream SR7 is a perennial stream that emanates from a culvert on the east side of Ripley Lane North, and flows west below the trestle. SR7 is a tributary to Lake Washington and is mapped as a containing fish habitat (Type F) by DNR and as a perennial non-fish bearing stream (Type Np) by the City. May Creek is located below the May Creek trestle. The stream flows west below the bridge and is a tributary to Lake Washington. May creek is a perennial stream and is a Type S (Shoreline of the State) watercourse per DNR and the City. The trestle is located above the special flood hazard area for the 100-year flood event as well as the floodway for May Creek. RMC 4-3-050 provides a Type S system with a jurisdictional area/buffer extending 200 feet from the ordinary high water mark or the edge of the floodway, whichever is greater. There are no federally-listed species in either SR6 or SR7 per Washington Department of Fish and Wildlife (WDFW) Priority Habitats and Species (PHS) on the web mapper. WDFW’s PHS on the Web maps Fall Chinook (Oncorhynchus tshawytscha) (federally-listed threatened), Coho (Oncorhynchus kitsutch), and winter steelhead (Oncorhynchus mykiss) (federally-listed threatened) within May Creek. Page 4 of 4 References Cowardin, L.M., V. Carter, F. Golet, and E.T. LaRoe. 1979. Classification of wetlands and deepwater habitats of the United States. FWS/OBS-70/31. 131 pp. Washington, D.C: U.S. Fish & Wildlife Service, Office of Biological Services. King County iMap. 2017. Available at http://gismaps.kingcounty.gov/iMap/ . Accessed November 10, 2017. U.S. Army Corps of Engineers (USACE). 1987. Corps of Engineers Wetland Delineation Manual. Technical Report. Y-87-1. Vicksburg, Mississippi: U.S. Army Corps of Engineers Environmental Laboratory. USACE. 2010. Regional Supplement to the Corps of Engineers Wetland Delineation Manual: Western Mountains, Valleys, and Coast Region, Version 2.0, ed. J.S. Wakeley, R.W. Lichvar, and C.V. Noble. ERDC/EL TR-10-3. Vicksburg, Mississippi: U.S. Army Engineer Research and Development Center. U.S. Department of Agriculture- National Resource Conservation Service (USDA-NRCS) Web Soil Survey. 2017. Available at https://websoilsurvey.sc.egov.usda.gov/App/HomePage.htm. Accessed November 10, 2017. U.S. Fish and Wildlife National Wetlands Inventory. 2017. Available at https://www.fws.gov/wetlands/data/mapper.HTML . Accessed November 10, 2017. Washington Department of Natural Resources (WDNR). 2017. Forest Practices Application Mapping Tool. Available online at https://fortress.wa.gov/dnr/protectiongis/fpamt/default.aspx, accessed on November 10, 2017. Washington Department of Ecology (Ecology). 2010. Determining the Ordinary High Water Mark For Shoreline Management Act Compliance in Washington State– Revised October 2016. Ecology publication #16-06-029. Olympia, WA. Washington Department of Fish and Wildlife Priority Habitats and Species (PHS) on the Web. 2017. Available at http://wdfw.wa.gov/mapping/phs/. Accessed November 10, 2017.