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HomeMy WebLinkAbout1634 Mitigation Plan (1-27-2017) FINAL MITIGATION PLAN HUNSAKER PROPERTY RENTON, WASHINGTON Prepared For: Pat Hunsaker 5201 Ripley Lane North Renton, Washington 98056-1503 Prepared By: TALASAEA CONSULTANTS, INC. Woodinville, Washington 8 November 2016 Mitigation Plan Hunsaker Property Renton, Washington Prepared For: Pat Hunsaker 5201 Ripley Lane North Renton, WA 98027 Prepared By: Talasaea Consultants, Inc. 150250 Bear Creek Road NE Woodinville, Washington 98077 (425) 861-7550 8 November 2016 Hunsaker Property Mitigation Plan 28 February 2017 Copyright © 2016 Talasaea Consultants, Inc. 1634 Mitigation Plan (12-22-2016) Page i EXECUTIVE SUMMARY PROJECT NAME: Hunsaker Property SITE LOCATION: The Site is an approximately 0.76-acre property located in Renton, Washington. The King County Tax Parcel number is 334330-2850. The property address is 5201 Ripley Lane North, Renton, Washington. The Public Land Survey System location is Section 29, Township 24 North, Range 5 East, Willamette Meridian. CLIENT: Pat Hunsaker PROJECT STAFF: Ann Olsen, Senior Project Manager; Jennifer Marriott, Senior Ecologist; Alicia Schulz, Landscape Designer; Kristen Numata, Ecologist. FIELD SURVEY: Talasaea Consultants evaluated the Site on 13 and 18 October 2016. DETERMINATION: The Site is located on Lake Washington with approximately 30 feet of natural shoreline. The rest of the shoreline is fill material that is managed as lawn. Lake Washington is a Shoreline of the State with a 100-foot setback. A lake fringe wetland occurs along the southern parcel boundary that is fed by a swale conveying road runoff to Lake Washington. This wetland was quickly rated as a Category III wetland with a 75-foot standard buffer. PROPOSED PROJECT: The Applicant proposes to re-construct a pre-existing porch and sidewalk that was located along the western and southern sides of the house. The existing porch and sidewalk was removed approximately two months ago to address issues with rotting support beams. During the removal of the old porch and sidewalk, fill material was accidentally pushed into a small area of onsite wetland. ASSESSMENT OF WETLAND IMPACTS: It is estimated that 34 square feet of fill was placed in the wetland. Estimations were completed using aerial imagery and photos included in the violation documentation. PROPOSED MITIGATION: The property will be restored to pre-existing conditions. This will be achieved by replanting the wetland with cattails, as any other native emergent could not outcompete the existing cattail stand. Untreated cedar will be placed between the replanted area and the lawn to help delineate the wetland edge along the south property line and avoid similar infractions in the future. This will also allow the property owner to keep and maintain the pre-existing lawn. Hunsaker Property Mitigation Plan 8 November 2016 Copyright © 2016 Talasaea Consultants, Inc. 1634 Mitigation Plan (11-3-2016) Page ii TABLE OF CONTENTS Executive Summary ......................................................................................................... i Table of Contents .............................................................................................................ii List of Figures, Tables and Appendices .......................................................................... iii Chapter 1. Introduction ................................................................................................ 1 1.1 Purpose of Report ............................................................................... 1 1.2 Statement of Accuracy ........................................................................ 1 Chapter 2. Property Description .................................................................................. 1 2.1 Property Location ................................................................................ 1 2.2 General Property Description .............................................................. 1 2.3 Existing Site Development ................................................................... 1 Chapter 3. Methodology .............................................................................................. 2 3.1 Background Data Reviewed ................................................................ 2 Chapter 4. Proposed Development and Critical Areas Impacts ................................... 2 4.1 Project Description .............................................................................. 2 Chapter 5. Proposed Mitigation ................................................................................... 2 5.1 Agency Policies and Guidance ............................................................ 2 5.2 Mitigation Summary ............................................................................. 3 5.3 Mitigation Design Elements ................................................................. 3 5.3.1 Plantings .............................................................................................. 3 5.3.2 Re-establish Lawn ............................................................................... 3 5.3.3 Temporary Irrigation System ............................................................... 3 5.3.4 Permanent Irrigation in West Lawn ..................................................... 3 5.4 Construction BMPs .............................................................................. 3 Chapter 6. Mitigation Goals & construction sequencing .............................................. 4 6.1 Goals ................................................................................................... 4 6.2 Mitigation Construction Sequencing .................................................... 4 6.3 Post-Construction Approval ................................................................. 4 6.4 Post-Construction Assessment ........................................................... 4 Chapter 7. Monitoring Plan .......................................................................................... 4 7.1 Monitoring Schedule ............................................................................ 4 7.2 Monitoring Update ............................................................................... 5 7.3 Photo Documentation .......................................................................... 5 7.4 Wildlife ................................................................................................. 5 7.5 Water Quality ....................................................................................... 5 7.6 Site Stability ......................................................................................... 5 Chapter 8. Summary ................................................................................................... 5 Chapter 9. References ................................................................................................ 7 Hunsaker Property Mitigation Plan 8 November 2016 Copyright © 2016 Talasaea Consultants, Inc. 1634 Mitigation Plan (11-3-2016) Page iii LIST OF FIGURES Figure 1 – Vicinity Map & Directions Figure 2 – Site Plan Figure 3 – Notes & Details LIST OF TABLES Table 1 – Projected Schedule for Site Evaluations and Reporting 5 APPENDICES Appendix A: Wetland Rating Form, Washington State Department of Ecology Wetland Rating System for Western Washington, Version 2 (2004, Revised in 2008), Talasaea Consultants, 2016. Hunsaker Property Mitigation Plan 8 November 2016 Copyright © 2016 Talasaea Consultants, Inc. 1634 Mitigation Plan (11-3-2016) Page 1 CHAPTER 1. INTRODUCTION 1.1 Purpose of Report This report is the result of a critical area study for the Hunsaker property (referred to hereinafter as the “Site”). The Site is located in Renton, Washington. The purpose of this report is to address the violation cited by the City of Renton, as well as propose mitigation for the impacts on the property. This report will provide and describe the following information:  General property description;  Methodology for critical areas investigation;  Mitigation approach;  Proposed mitigation design;  Site specific goals and construction sequencing; and  Monitoring plan 1.2 Statement of Accuracy Wetland characterizations and ratings were conducted by trained professionals at Talasaea Consultants, Inc., and adhered to the protocols, guidelines, and generally accepted industry standards available at the time the work was performed. The conclusions in this report are based on the results of analyses performed by Talasaea Consultants and represent our best professional judgment. To that extent and within the limitation of project scope and budget, we believe the information provided herein is accurate and true to the best of our knowledge. Talasaea does not warrant any assumptions or conclusions not expressly made in this report, or based on information or analyses other than what is included herein. CHAPTER 2. PROPERTY DESCRIPTION 2.1 Property Location The Site is an approximately 0.76-acre property located in Renton, Washington. The King County Tax Parcel number is 334330-2850. The property address is 5201 Ripley Lane North, Renton, Washington. The Public Land Survey System location is Section 29, Township 24 North, Range 5 East, Willamette Meridian. 2.2 General Property Description The topography of the Site is sloping from the east to the west. The property occurs along the shoreline of Lake Washington. A bioswale is located along the south property line which discharges into a lake-fringe wetland. Vegetation on the undeveloped portions of the Site is maintained as lawn for several decades. 2.3 Existing Site Development The Site is developed as a single-family residence with lawn along the southern and western edges of the property. Hunsaker Property Mitigation Plan 8 November 2016 Copyright © 2016 Talasaea Consultants, Inc. 1634 Mitigation Plan (11-3-2016) Page 2 CHAPTER 3. METHODOLOGY The critical areas analysis of the Site consisted of a preliminary assessment of the Site and the immediate surrounding area using published environmental information. 3.1 Background Data Reviewed Background information from the following sources was reviewed:  US Fish and Wildlife Service (USFWS), Wetlands Online Mapper (National Wetlands Inventory) (U.S. Fish and Wildlife Service 2016) (www.wetlandsfws.er.usgs.gov/wtlnds/launch.html);  Natural Resources Conservation Service, Web Soil Survey (Natural Resources Conservation Service 2016)(www.websoilsurvey.nrcs.usda.gov/app/);  King County GIS Database (King County 2016);  Washington Department of Fish and Wildlife (WDFW) Priority Habitat and Species (PHS) Database on the Web (www.wdfw.wa.gov/mapping/phs/);  StreamNet database, 2016 (www.streamnet.org)  SalmonScape database, 2016 (www.wfw.wa.gov/mapping/salmonscape/databases);  Orthophotography from Earth Explorer (USGS), Google Earth; and  Relevant studies completed or ongoing in the vicinity of the Site. CHAPTER 4. PROPOSED DEVELOPMENT AND CRITICAL AREAS IMPACTS 4.1 Project Description The Applicant proposes to replace a pre-existing porch and sidewalk to replace rotting wood supports. The patio and sidewalk were initially constructed with the house in 1979. The Applicant removed these elements two months ago, and in the process, inadvertently pushed a small amount (34 sf) of fill into an onsite wetland. Impacts outlined in the violation by the City of Renton dated 29 September 2016 (CODE16- 000650) include:  Fill and grade over the existing lawn; and  Gravel imported and placed between the house and critical area to the south In addition to replacing the old porch and sidewalk, the Applicant proposes to install an automated irrigation system to the remaining lawn space as part of the general maintenance of these areas. CHAPTER 5. PROPOSED MITIGATION 5.1 Agency Policies and Guidance The mitigation proposed for critical areas impacts is in accordance with the following policies, codes, and regulatory guidance: Renton Municipal Code, Chapter 4-3-090, “Shoreline Master Program Regulations” Hunsaker Property Mitigation Plan 8 November 2016 Copyright © 2016 Talasaea Consultants, Inc. 1634 Mitigation Plan (11-3-2016) Page 3 5.2 Mitigation Summary To mitigate for the minor wetland encroachment of 34 sf, the Applicant proposes to remove the fill from the wetland, install 8x8” untreated cedar timber at the edge of the lawn outside of the wetland boundary, and replant with cattails (Typha latifolia). 5.3 Mitigation Design Elements 5.3.1 Plantings Existing wetland vegetation is dominated by cattails, bindweed (Convulvulus arvensis) and birdsfoot trefoil (Lotus corniculatus). Areas that were identified as fill will be removed and replaced with cattails. We recognize that other native emergent vegetation would provide better forage and habitat opportunities in the wetland, however, cattails will likely outcompete these species in a few years. 5.3.2 Re-establish Lawn The lawn to the south side of the property will be re-established to pre-existing conditions. A series of 8x8” untreated cedar timber will be placed on a setback from the wetland edge to define the lawn edge. Fill will be placed on the north side of the installed timber to establish the lawn (gravel, topsoil, etc). 5.3.3 Temporary Irrigation System Temporary irrigation will be not be necessary, as hydrology is continuously provided by Lake Washington and the street runoff from the east. 5.3.4 Permanent Irrigation in West Lawn The Applicant will be installing irrigation along the western lawn located along Lake Washington as part of ongoing lawn maintenance. According to RMC 4-3- 090(D)(2)(d)(ix)(d), “Existing facilities: maintenance, repair or operation of existing structures, facilities, or improved areas, including minor modification of existing serviceable structures within a buffer zone does not adversely impact wetland functions, and subject to the provisions for nonconforming use and facilities in chapter 4-10 RMC.” The western lawn is a pre-existing non-conforming use that is in need of irrigation for continued maintenance, and thus meets the intent of this stipulation. 5.4 Construction BMPs The proposed project will implement BMPs as needed during construction to minimize impacts to the on-site critical areas during the construction process. The proposed development will comply with the latest edition of the King County Stormwater Management Manual and all applicable construction site erosion control and stormwater Best Management Practices (BMPs). BMPs to be implemented may include, but are not limited to:  Silt fences;  Straw bale dams;  Erosion control mesh, netting, seeding, or other cover for exposed soils; and  Covered, seeded, or otherwise stabilized soil stockpiles. Hunsaker Property Mitigation Plan 8 November 2016 Copyright © 2016 Talasaea Consultants, Inc. 1634 Mitigation Plan (11-3-2016) Page 4 CHAPTER 6. MITIGATION GOALS & CONSTRUCTION SEQUENCING 6.1 Goals The goal of the proposed mitigation plan is to replace the ecological functions and values lost due to small amounts of wetland fill. To accomplish these goals, the proposed mitigation plan will:  Enhance 34 sf of wetland 6.2 Mitigation Construction Sequencing The following provides the general sequence of activities anticipated to be necessary to complete this mitigation project. Some of these activities may be conducted concurrently as the project progresses. 1. Conduct a site meeting between the contractor, Talasaea Consultants, and the owner’s representative to review the mitigation plans and work areas. 2. Survey mitigation project limits and flag or otherwise clearly mark boundaries of mitigation work areas. 3. Install any erosion and sedimentation control BMPs necessary for work in the mitigation areas. 4. Remove fill. 5. Install untreated cedar timber that delineates the lawn edge. 6. Place topsoil or amend soils in restored buffer areas. 7. Plant cattails as shown on plans. 6.3 Post-Construction Approval Talasaea Consultants shall notify the City in writing when the mitigation planting is completed for a final site inspection and subsequent final approval. Once final approval is obtained in writing from the City, the monitoring period will begin. 6.4 Post-Construction Assessment Once the mitigation construction is approved, a qualified wetland ecologist/biologist from Talasaea Consultants shall conduct a post-construction baseline assessment. The purpose of this assessment will be to establish baseline conditions at Year 0 of the required monitoring period. A Baseline Assessment report including as-built drawings will be submitted to the City. The as-built plan set will depict any field changes to plantings or other features in relation to the original approved mitigation plan. CHAPTER 7. MONITORING PLAN 7.1 Monitoring Schedule To ensure the success of this project, Talasaea Consultants will conduct two site visits and supply an update to the City according to the schedule presented in Table 1 below. Monitoring will be performed by a qualified biologist or ecologist. Hunsaker Property Mitigation Plan 8 November 2016 Copyright © 2016 Talasaea Consultants, Inc. 1634 Mitigation Plan (11-3-2016) Page 5 Table 1. Projected Schedule for Site Evaluations and Reporting Year Date* Site Visit Update Due to City 1 Spring X Fall X X *Actual dates will depend on project construction schedule, to be determined. 7.2 Monitoring Update The update to the City will be sent one year after the construction is completed. Wetland health, survival and untreated cedar stabilization will be discussed as standards of site performance. 7.3 Photo Documentation Locations will be established within the mitigation area from which panoramic photographs will be taken during each site visit. These photographs will document general appearance and relative changes within the plant community. Review of the photos over one year will provide a semi-quantitative representation of success of the planting plan. 7.4 Wildlife Birds, mammals, reptiles, amphibians, and invertebrates observed in the wetland and buffer areas (either by direct or indirect means) will be identified and recorded during scheduled monitoring events, and at any other times observations are made. Direct observations include actual sightings, while indirect observations include tracks, scat, nests, song, or other indicative signs. The kinds and locations of the habitat with greatest use by each species will be noted, as will any breeding or nesting activities. 7.5 Water Quality Water quality will be assessed qualitatively; unless it is evident there is a serious problem. In such an event, water quality samples will be taken and analyzed in a laboratory for suspected parameters. Qualitative assessments of water quality include:  Oil sheen or other surface films,  Abnormal color or odor of water,  Stressed or dead vegetation or aquatic fauna,  Turbidity, and  Absence of aquatic fauna. 7.6 Site Stability Observations will be made of the general stability of slopes and soils in the mitigation areas during each monitoring event. Any erosion of soils or slumping of slopes will be recorded and corrective measures will be taken. CHAPTER 8. SUMMARY A critical areas study was conducted for the Hunsaker Property located in Renton, Washington. The site is approximately 0.76-acres in size. The address is 5201 Ripley Lane North. The majority of the Site is developed as a single family residence with lawn to the west and south. Lake Washington is located immediately to the west. The Site Hunsaker Property Mitigation Plan 8 November 2016 Copyright © 2016 Talasaea Consultants, Inc. 1634 Mitigation Plan (11-3-2016) Page 6 occurs within the Shoreline Management Zone and proposed work will occur within this zone. However, all activities are allowable per RMC 4-3-090(D)(2)(d)(ix)(d) and 4-10, and are except from shoreline regulation. This report was written to address a violation from the City of Renton dated 29 September 2016. The Applicant is proposing 34 square feet of native emergent enhancement within the wetland and a series of 8”x8” untreated cedar timber that will be installed to define the lawn edge. Hunsaker Property Mitigation Plan 8 November 2016 Copyright © 2016 Talasaea Consultants, Inc. 1634 Mitigation Plan (11-3-2016) Page 7 CHAPTER 9. REFERENCES Cowardin, L.M., V. Carter, F.C. Golet, and E.T. LaRoe. 1979. Classification of Wetlands and Deepwater Habitats of the United States. U.S. Fish and Wildlife Service, Department of the Interior. FWSOBS-70/31. Hruby, T. Washington State Wetland Rating System for Western Washington - Revised. Olympia, WA: Washington State Department of Ecology Publication #04- 06-025, 2008. Iowa State University. 1995. Hydric Soils of Washington State. U.S. Department of Agriculture, Natural Resources Conservation Service. December 5. Soil Survey Staff, Natural Resources Conservation Service, United States Department of Agriculture. Web Soil Survey. Available online at http://websoilsurvey.nrcs.usda.gov/. Accessed [10/24/2016]. U.S. Department of Agriculture, Soil Conservation Service. June, 1991. Hydric Soils of the United States. U.S. Fish and Wildlife Service. 2016. National Wetlands Inventory Map. Washington State Department of Fish and Wildlife [Map Online], Olympia (WA): SalmonScape [10/24/2016]. URL: <http//wdfw.wa.gov/mapping/salmonscape/index.html> Hunsaker Property Mitigation Plan 8 November 2016 Copyright © 2016 Talasaea Consultants, Inc. 1634 Mitigation Plan (11-3-2016) Figures FIGURES Figure 1 – Vicinity Map & Directions Figure 2 – Site Plan Figure 3 – Notes & Details Hunsaker Property Mitigation Plan 8 November 2016 Copyright © 2016 Talasaea Consultants, Inc. 1634 Mitigation Plan (11-3-2016) Appendix B APPENDIX A Wetland Rating Form, Washington State Department of Ecology Wetland Rating System for Western Washington, Version 2 (2004, Revised in 2008), Talasaea Consultants, 2016.