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HomeMy WebLinkAboutRS_SVC Site Visit Memo_180405_v1 Soundview Consultants LLC April 4, 2018 1155.0024 – Harbour Homes Page 1 2907 Harborview Drive, Suite D Gig Harbor, WA 98335 Technical Memorandum To: Alex Morganroth, Associate Planner File Number: 1155.0024 City of Renton, CED, Planning Division From: Don Babineau, Environmental Planner Date: April 4, 2018 Re: 14120 160th Ave. SE- Technical Memorandum - Ref. No.: 32847.B - follow-up site visit. Dear Alex Morganroth, Thank you for taking the time to meet with our team and OTAK onsite on March 14, 2018. This memorandum is in response to the comments made during the meeting with OTAK regarding the critical areas review for the proposed Cedars at the Highlands preliminary plat located at 14120 160th Avenue Southeast in Renton, Washington, 98059 (King County Parcel number 145750-0110). Non-Wetland Areas and Onsite Southern Drainage Otak and Soundview Consultants LLC (SVC) discussed the ponded areas in the northwest portion of the site which Sewall originally assessed as uplands prior to the recent fill brought onto the site. OTAK agreed that the SVC memo adequately assessed and documented the area as anthropogenically altered as a result of the compacted fill and was not a natural wetland area. As such, it was agreed the area would not be considered a regulated critical area. The culverted drainage through the ponded area draining to the southeast corner of the site was also determined to be a nonregulated manmade feature. Wetland A and Associated Drainage Otak and SVC discussed Wetland A and the associated drainage through the wetland. While the drainage associated with Wetland A does not meet the definition of a stream per City of Renton code as it does not flow to a perennial waterbody via an above ground channel system, because the channel exhibited natural stream like characteristics, it was agreed that the drainage would be treated as a Type Ns stream. While Otak staff agreed with the delineation of Wetland A, they maintained their assessment of the hydrogeomorphic (HGM) classification of the wetland as a depressional wetland. SVC does not concur with this classification. From the onsite inspection, it was clear there is no significant depressional function of the wetland to meet the threshold of being classified as a depressional wetland. While there are obstructions (tree branches and logs) slightly impeding the surface flow of the drainage within the wetland, there are not adequate depressions within the streambed to classify the wetland as depressional. To confirm the lack of depressions within Wetland A, following the site, Soundview Consultants LLC April 4, 2018 1155.0024 – Harbour Homes Page 2 visit SVC conducted a highly precise LIDAR analysis of the topography of the wetland area (see Attachment A). From the analysis it is clear to see the geomorphology of Wetland A resembles a chute with an even gradient along the channel and no depressions or hummocks which would create depressional areas. For a wetland to be depressional, it must impound water. Wetland A does not have the capability to significantly impound water. SVC correctly used the accepted HGM classification system as outlined by Brinson (1993) and in accordance with Section 5.1 and the classification key of the rating form located in Appendix A of the Washington State Wetland Rating System for Western Washington (Hruby, 2014). Otak staff cited a portion of Section 5.1 during the sit visit as justification for classifying Wetland A as depressional and the citation was one sentence taken out of context. He said that according to the manual, slope wetlands do not receive water through surface flow. The following is the full, accurate portion of the manual to which he referred: Slope wetlands with surface flows can be distinguished from Riverine wetlands by the lack of a defined stream bed with banks. Slope wetlands may develop small rivulets along the surface, but they serve only to convey water away from the wetland. There is no surface flow coming into the wetland through channels. This portion of the manual is in regard to distinguishing slope versus riverine wetlands, and it was agreed Wetland A is clearly not a riverine wetland. This portion of the manual has nothing to do with determining if a wetland is depressional. To determine a wetland’s HGM classification, the rapid assessment procedure is to follow the key located in the front of the 2014 rating form which consists of a set of progressive yes/no questions. The first three questions on the key determine if the wetland is either a tidal fringe, flats, or lake fringe wetland and are obviously not applicable. The fourth question deals with slope wetlands and has three criteria required to meet the classification: • The wetland is on a slope, • The water flows through the wetland in one direction and usually come from seeps. It may flow subsurface, as sheet flow or in a swale without distinct banks, • The water leaves the wetland without being impounded. Wetland A has a clear, continuous slope with seasonal main channel flowing through it and a saturated slope edge which feeds into the main channel. Hydrology flows through the wetland in one direction. The wetland receives its hydrology from groundwater and direct precipitation and leaves the wetland without significant impoundment. The second criteria may appear to add some uncertainty but having a stream channel at the lowest point cross-sectionally within a slope wetland is common. Technically, Wetland A is actually two separate wetlands flowing on either side of the stream channel to that channel; however, per the 2014 manual guidance, slope wetlands are to be treated as one wetland when the stream bisecting them is as narrow as Stream Z. From the attached LIDAR exhibit, it is clear to see that most of the wetland area is uphill from the channel running through the wetland. This is an important distinction because it shows the wetland does not receive the majority of its hydrology from the stream. Instead, it contributes to the stream’s hydrology through lateral flow to the central Soundview Consultants LLC April 4, 2018 1155.0024 – Harbour Homes Page 3 stream channel. At times of heavy flow, the stream will encroach on a small portion of the wetland area, but this increased flow is not the main source of wetland hydrology. When the stream stops flowing, Wetland A persists in its hydrated state because groundwater is the wetland’s main source of hydrology. A depressional classification would infer that the wetland has areas of significant impoundment that would allow for stagnation and fallout of particulates. The wetland on the subject property was observed to have micro-depressions that are receiving flow from the main channel, however these micro-depressions were observed to be continuously flowing, highly oxygenated, and not providing the potential for anaerobic conditions. Soil data supports these observations with a lack of obvious hydric soil conditions that would be expected in a depressional wetland. Conclusion Because the Wetland A is properly classified as a slope wetland, it is accurately rated per SVC’s previous assessment as a Category IV wetland which requires a standard 40-foot buffer per Renton Municipal Code (RMC) Title IV, Chapter 3 (4-3-500). Per SVC’s original assessment and the site meeting, this is the only regulated wetland onsite. SVC and Otak agreed the drainage flowing through Wetland A is the only regulated stream feature and should be treated as a Type Ns stream requiring a 50 -foot buffer per RMC Title IV, Chapter 3 (4-3-500). Please contact me with any questions or concerns you may have regarding this matter. Sincerely, April 4, 2018 Don Babineau Date Environmental Planner/Project Manager Soundview Consultants LLC 2907 Harborview Drive, Suite D Gig Harbor, WA 98335 don@soundviewconsultants.com Soundview Consultants LLC April 4, 2018 1155.0024 – Harbour Homes Page 4 References Brinson, M. M., 1993. “A Hydrogeomorphic Classification for Wetlands,” Technical Report WRP DE-4, U.S. Army Engineer Waterways Experiment Station, Vicksburg, MS. Cowardin, L.M., V. Carter, F. Golet, and E.T. LaRoe. 1979. Classification of Wetlands and Deepwater Habitats of the United States. U.S. Fish & Wildlife Service. Washington D.C. Environmental Laboratory. 1987. Corps of Engineers Wetlands Delineation Manual. Technical Report Y- 87-1, US Army Engineer Waterways Experiment Station, Vicksburg, Mississippi. Federal Geographic Data Committee. 2013. Classification of Wetlands and Deepwater Habitats of the United States. FGDC-STD-004-2013. Second Edition. Wetlands Subcommittee, Federal Geographic Data Committee and U.S. Fish and Wildlife Service, Washington, DC. Hruby, T. 2014. Washington State Wetland Rating System for Western Washington – Revised. Washington State Department of Ecology Publication # 14-06-029. Lichvar, R.W., D.L. Banks, W.N. Kirchner, and N.C. Melvin. 2016. The National Wetland Plant List: 2016 wetland ratings. Phytoneuron 2016-30: 1-17. Published 28 April 2016. ISSN 2153 733X Munsell Color. 2000. Munsell Soil Color Charts. New Windsor, New York. Natural Resources Conservation Service (NRCS). 1995. Hydric Soils of Washington. U.S. Department of Agriculture. Washington D.C. NRCS. 2001. Hydric Soils List: King County, Washington. U.S. Department of Agriculture. Washington D.C. Null, William, Skinner, Gloria, and Leonard, William. 2000. Wetland Functions Characterization Tool for Linear Projects. Washington State Department of Transportation. OTAK, Inc. 2017. Review of Sewall Wetland Consulting, Inc. Critical Areas Report. Redmond, WA. Renton Municipal Code (RMC). 2017. Title IV, Chapter 3 – Environmental Regulations and Overlay Districts. Passed December 11, 2017. Snyder, Dale E., Gale, Philip S., and Pringle, Russell F. 1973. Soil Survey of King County Area, Washington. Soil Conservation Service. U.S. Army Corps of Engineers. 2010. Regional Supplement to the Corps of Engineers Wetland Delineation Manual: Western Mountains, Valleys, and Coast Region (Version 2.0), ed. J. S. Wakeley, R. W. Lichvar, and C. V. Noble. ERDC/EL TR-10-3. Vicksburg, MS: U.S. Army Engineer Research and Development. Soundview Consultants LLC April 4, 2018 1155.0024 – Harbour Homes Page 5 Attachment A – Lidar Analysis Exhibit CEDARS OF THE HIGHLAND - LIDAR EXHIBIT DATE: JOB: BY: SCALE: VARIES FIGURE NO. 3/16/2018 DLS 1 CEDARS AT THE HIGHLANDS 14120 160TH AVE SE, RENTON, WA 98059 KING COUNTY PARCEL NUMBERS:45750-0106 1155.0024 ! ! ! ! ! !Wetland Centerline Wetland Boundary Elevation in Feet 426.6 - 428.1 425.7 - 426.6 425 - 425.7 424.3 - 425 423.7 - 424.3 423.1 - 423.7 422.5 - 423.1 421.8 - 422.5 421.1 - 421.8 420.3 - 421.1 419.6 - 420.3 418.8 - 419.6 418.1 - 418.8 417.3 - 418.1 416.6 - 417.3 415.9 - 416.6 415.3 - 415.9 414.7 - 415.3 414 - 414.7 413.3 - 414 412.5 - 413.3 411.8 - 412.5 411.2 - 411.8 410.4 - 411.2 409.5 - 410.4 408.7 - 409.5 407.8 - 408.7 407.1 - 407.8 406.5 - 407.1 405.9 - 406.5 405.2 - 405.9 404 - 405.2 Top Elevation 418.5 Feet Bottom Elevation 408 Feet Length of Centerline 316 Feet Wetland A 3.3% Slope ¢ Soundview Consultants LLC April 4, 2018 1155.0024 – Harbour Homes Page 6 Attachment D – Qualifications Don Babineau Environmental Planner/Project Manager Professional Experience: >10 years Don Babineau is an Environmental Planner and Project Manager with a diverse background in urban and commercial forestry, land planning, landscape architecture, stormwater monitoring and civil engineering. Don has experience as a Forester with Washington State Department of Natural Resources stream typing and delineating stream protection zones, as well as implementing Washington State’s Habitat Conservation Plan to foster the creation of old-growth forest characteristics on state trust lands. Don earned a Bachelor of Science degree in Forest Ecosystems Management and a Bachelor of Landscape Architecture degree, both from the University Of Idaho. Don has been formally trained by the Washington State Department of Ecology in the use of the Washington State Wetland Rating System. In addition, he has received formal training in wetland delineation from the Northwest Environmental Training Center and is an experienced certified erosion and sediment control lead (CESCL). He is also a Pierce County qualified Professional Forester. Richard Peel Wetland Scientist Professional Experience: 5 years Richard Peel is a Wetland Scientist with professional experience in wetland ecology, monitoring, and delineation throughout Washington and Oregon. Richard is Washington State trained in conducting wetland delineations, assessing wetland systems, mitigation planning and design, implementation of monitoring programs, mitigation monitoring and reporting. He also has extensive experience in an analytical laboratory using state-of-the-art equipment in bacteriological and chemical analysis of soil and water samples. Richard is a graduate of The Evergreen State College, with dual degrees in Ecology and Economics. He has focused his academic career on ecology, disturbance ecology, chemistry, and the economic impacts of current environmental management. Richard has extensive training and field experience in wetland related disciplines, and has experience in wetlands both east and west of the Cascades. He has been trained by the Washington State Department of Transportation (WSDOT) Wetland Ecology and Monitoring team in the use of the wetland delineation, mitigation, monitoring, and restoration techniques. In addition, he was directed by WSDOT’s Wetland Protection and Preservation Policy to ensure wetlands are preserved and protected whenever possible. This direction ensures no net loss in the quantity or quality of wetlands in the future and minimization of impacts to wetlands in the present.