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Home My WebLink AboutMiscCH;.1 . F<er;:on F!1-~ 1111, -·r._:; ~-·1 1,._,.1~~1,J, -. Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation A Separable Element of the Green-Duwamish General Investigation Ecosystem Restoration Project Renton, WA Ma 2010 m US Army Corps of Engineers® Seattle District Upper Springbrook Creek Channel Realignment and Rehabilitation Final Environmental Assessment May2010 Responsible Agencies: The agencies responsible for this project are the U.S. Anny Corps of Engineers, Seattle District (Corps), and the City of Renton. Summary: Upper Springbrook Creek currently flows through a roadside ditch overgrown with invasive weeds that parallels the north side of South 55th Street for approximately 900 feet before it flows underneath Highway 167. In this reach, the creek is located less than 10 feet from the roadside, and the only vegetative cover consists of dense stands of Japanese knotweed and Himalayan blackberry. Coho salmon ( Oncorhynchus kisutch) utilize this stream for spawning, rearing, foraging, and as refuge habitat. However, during high flow events, the straight, wood devoid channel provides little refugia, allowing for the potential of juvenile fish to be flushed further downstream. This lack of channel complexity reduces the streams ability to provide suitable habitat for fish and wildlife. The Corps and City of Renton propose to relocate Upper Springbrook Creek away from its straightened roadside location adjacent to South 55th Street and into a more natural stream channel, as well as replacing the culvert underneath South 55th Street with a design more conducive to fish passage. Tue relocated stream will flow into a constructed streambed that will meander through a forested wetland that borders Highway 167. This project will increase available spawning habitat for adult fish, and will enhance rearing, foraging, and refuge habitat for juvenile salmonid and resident fish in Upper Springbrook Creek by creating off-channel habitat areas, removing the stream from a source of potential water quality contamination, through provision of a riparian buffer, and by allowing access to higher quality habitat located upstream. In accordance with the National Environmental Policy Act (NEPA), this document evaluates the potential environmental impacts of the proposed restoration alternatives. Tue project does not constitute a major Federal action that will significantly affect the quality of the human or natural environment. Tue Corps will use best management practices to minimize potential adverse effects to aquatic and terrestrial resources. Impacts to air quality, noise, and water quality will generally be highly localized and short in duration, and wetland impacts will be mitigated to a level of insignificance by providing enhanced aquatic functions and values in the project area as a result of the creek relocation. THE OFFICIAL CO"MMENT PERIOD FOR THIS ENVIRONMENTAL ASSESSMENT WAS FROM 6 APRIL 2010 TO 6 MAY 2010. This document is available online under the project name "Upper Springbrook Creek" at: http://www.nws. usace.army .millers/doc_ table.cfrn. Fina] Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 ii Please send comments, questions, and requests for additional information to: Chemine Jackels Environmental Resources Section U.S. Army Corps of Engineers P.O. Box 3775 Seattle, Washington 98124-3755 chemine.r .jackels@usace.army.mil phone: 206-764-3646 Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 iii 1. INTRODUCTION ..................................................................................................................................................... 1 1.1 PROJECT LOCATION AND SETTING .......................................................................................................... 2 1.2 PROJECT PURPOSE AND NEED .................................................................................................................... 3 1.3 AUTHORITY ....................................................................................................................................................... 4 1.4 ASSOCIATED STUDIES AND REPORTS ....................................................................................................... 4 2. ALTERNATIVES CONSIDERED .......................................................................................................................... 5 2.1 THE NO-ACTION ALTERNATIVE ................................................................................................................. 5 2.2 ALTERNATIVE! -Channel Realignment with Bioengineered Features to Minimize Bank Overtopping (Preferred alternative-see Appendix A for projects plans) ............................................................................................. 5 2.2.1 Channel Alignment ................................................................................................................................................ 5 2.2.2 Placement of Large Woody Debris (L WD) ........................................................................................................... 6 2.2.3 Bioengineered Floodplain Improvements .............................................................................................................. 7 2.2.4 Replacement of Culvert on South 55th Street ........................................................................................................ 8 2.2.5 Decommissioning of the Existing Channel .......................................................................................................... 10 2.2.6 Riparian Plantings ................................................................................................................................................ 10 2.2.6 Construction Timing and Erosion Control ........................................................................................................... 11 2.3 ALTERNATIVE 2-Channel Realignment with a Berm to Contain Bank Overtopping ........................... 12 3. EXISTING CONDITIONS .................................................................................................................................... 12 3.1 PHYSICAL CHARACTERISTICS .................................................................................................................. 13 3.1.1 Geology and Soils ................................................................................................................................................ 14 3.1.2 Hazardous and Toxic Materials ........................................................................................................................... 14 3.1.3 Hydro logic Regime .............................................................................................................................................. 15 3.2 WATER QUALITY ........................................................................................................................................... 16 3.3 VEGETATION ................................................................................................................................................... 16 3.4 AQUA TIC BIOTA ............................................................................................................................................. 17 3 .4.1 Fish ...................................................................................................................................................................... 17 3.4.2 Benthic Invertebrates ........................................................................................................................................... 18 3.5 WILDLIFE ......................................................................................................................................................... 18 3.6 THREATENED AND ENDANGERED SPECIES .......................................................................................... 19 3.7 CULTURAL RESOURCES .............................................................................................................................. 20 3.8 NATIVE AMERICAN CONCERNS ................................................................................................................ 21 3.9 LAND USE .......................................................................................................................................................... 21 3.10 RECREATION ................................................................................................................................................... 22 3.11 AIR QUALITY AND NOISE ............................................................................................................................ 22 3.12 TRANSPORTATION ........................................................................................................................................ 23 3.13 AESTHETICS .................................................................................................................................................... 23 4. ENVIRONMENTAL EFFECTS OF THE PREFERRED ALTERNATIVE .................................................... 24 4.1 PHYSICAL CHARACTERISTICS .................................................................................................................. 24 4.1.1 Geology and Soils ................................................................................................................................................ 24 4.1.1.1 ............................................................................................................................................................................ 24 4.1.2 Hazardous and Toxic Materials ........................................................................................................................... 24 4.1.3 Hydrologic Regime .............................................................................................................................................. 25 4.2 WATER QUALITY ........................................................................................................................................... 25 4.3 VEGETATION ................................................................................................................................................... 26 4.4 AQUATIC BIOTA ............................................................................................................................................. 27 4.4.1 Fish ...................................................................................................................................................................... 27 4.4.2 Aquatic Invertebrates ........................................................................................................................................... 28 4.5 WILDLIFE ......................................................................................................................................................... 28 4.6 THREATENED AND ENDANGERED SPECIES .......................................................................................... 29 4.7 CULTURAL RESOURCES .............................................................................................................................. 31 4.8 NATIVE AMERICAN CONCERNS ................................................................................................................ 31 4.9 LAND USE .......................................................................................................................................................... 32 4.10 RECREATION ................................................................................................................................................... 32 4.11 AIR QUALITY AND NOISE ............................................................................................................................ 32 4.12 TRANSPORTATION ........................................................................................................................................ 34 4.13 AESTHETICS .................................................................................................................................................... 34 5. UNAVOIDABLE ADVERSE EFFECTS .............................................................................................................. 34 6. CUMULATIVE IMPACTS .................................................................................................................................... 35 7. COORDINATION .................................................................................................................................................. 36 8. ENVIRONMENTAL COMPLIANCE .................................................................................................................. 36 8.1 National Environmental Policy Act .................................................................................................................. 36 8.2 Endangered Species Act of 1973 as amended (PL 93-205) .............................................................................. 37 8.3 Clean Water Act ................................................................................................................................................. 37 8.4 Coastal Zone Management Act (16 USC 1456 et. seq.) ................................................................................... 37 8.5 National Historic Preservation Act (16 U.S.C. 470) ........................................................................................ 38 8.6 Fish and Wildlife Coordination Act (16 U.S.C. 661) ....................................................................................... 38 8.7 Bald and Golden Eagle Protection Act (BGEPA) (16 U.S.C. 668-668d) ........................................................ 38 8.8 Wild and Scenic Rivers Act (16 U.S.C. 1271-1287) ················-·······································································38 8.9 Executive Order 12898, Environmenta] Justice ................. ,,.,_,,, .................................................................... 38 8.10 Executive Order 11990, Protection of Wetlands, May 24, 1977 ••••••.••.••.••.•••••••.•..••..••.••.•••.••.•••.••.•••••.••.•••••.••. 39 8.11 Executive Order 11988, Floodplain Management, 24 May 1977 .................................................................... 39 9. CONCLUSION ........................................................................................................................................................ 39 LITERATURE CITED .................................................................................................................................................... 40 Figures Figure 1: Figure 2: Figure 3: Figure 4: Tables Table 1: Table 2: Table 3: Table 4: Table 5: Upper Springbrook Creek Location and BoundaJY .......................................................................... 3 Upper Springbrook Creek Watershed and TopographY. .................................................................... 14 South 55"' Street Culvert ........................................................................................................... 18 Land Use Around the Upper Springbrook Creek Project Location ...................................................... 22 Riparian Plantings in the New Channel... ..................................................................................... 11 Discharge at Upper Springbrook Creek ......................................................................................... 15 Green/Duwarnish River Threatened and Endangered Species ............................................................ 19 Threatened and Endangered Determination for the Green/Duwamish Ecosystem Restoration __________________ 30 Estimated Emission (tons) of Air Pollutants and Green House Gases from Operation of Vehicles and Construction Equipment for Upper Springbrook Creek Chanoel Realignment and Rehabilitation ............ 33 Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 ii Appendices Appendix A: Project Plans Appendix B: Wetland Delineation Report and Rating Forms Appendix C: Restoration, Maintenance, and Monitoring Plan Appendix D: Concurrence letters from USFWS and NOAA Appendix E: 401 Water Quality Certification Appendix F: 404(b)(l) Analysis Appendix G: Coastal Zone Consistency Determination Appendix H: SHPO Concurrence arid Tribal Letters Appendix I: Public comments recieved Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 iii 1. INTRODUCTION The Corps of Engineers (Corps) and the City of Renton are proposing to realign a portion of Springbrook Creek, which is currently located in a roadside ditch that is directly parallel to South 55th Street, through a 100 foot easement on an adjacent forested wetland in the summer of 2011. The proposed work involves: (1) Replacing the culvert that crosses South 55th Street with a design approved by Washington Department offish and Wildlife (WDFW) for fish passage, (2) Realigning the channel through an adjacent forested wetland that lies to the north of South 55th Street, and (3) Placing woody debris in the new channel and planting native riparian vegetation to create complex habitat for aquatic biota. In accordance with the National Environmental Policy Act (NEPA), this Environmental Assessment (EA) evaluates the potential environmental impacts of the proposed restoration project. This restoration activity is being conducted as part of the Green/Duwamish River Basin Ecosystem Restoration Project (ERP). In the ERP, the Corps has served as the lead in developing restoration projects for the Green/Duwamish River, working with local agencies to identify, evaluate, prioritize, and coordinate implementation of potential restoration projects to assure that the restoration programs and projects from the various agencies complement each other. As part of this ecosystem approach, two major documents have been prepared that provide general information regarding the Green/Duwamish River basin and its associated existing conditions, fish and wildlife populations, and potential impacts on federally listed endangered or threatened species. The documents are as follows: • Final Programmatic Environmental Impact Statement and Restoration Plan (FPEIS) for the Green/Duwamish River Basin Ecosystem Restoration Project, prepared by the Seattle District Corps and King County DNR in November 2000. • Programmatic Biological Assessments for Green/Duwamish Ecosystem Restoration Project, King County, Washington. Separate Biological Assessments were prepared for species under National Marine Fisheries and US Fish and Wildlife jurisdictions for the Seattle District Corps by Jones & Stokes, June 2000. Information from these reports has been adopted in this document largely by reference. The purpose and need statement for the Programmatic Final NEPA/SEP A Environmental Impact Statement (DEIS) and Restoration Plan was to improve the overall health of the Green/Duwamish River basin ecosystem for fish and wildlife species by increasing the quantity, quality, diversity, and connectivity of available habitat. The need for such improvement to the ecosystem was well established from years of study conducted by the U.S. Army Corps of Engineers (Corps or USACE), King County, the Port of Seattle, the Muckleshoot Indian Tribe Fisheries Department, the Washington State Department offish and Wildlife, and others. The Programmatic EIS assessed the Corps proposal to implement a basin wide restoration program in the Green/Duwamish River. The programmatic Green/Duwamish Ecosystem Restoration Project EIS can be accessed online at: 1 Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 http://www.nws.usace.army.mil/ers/index.cfin?status=l, under the project name "Green Duwamish Ecosystem Restoration Project." The purpose of preparing a progranunatic EIS was to expedite and provide a point of departure for future site-specific projects, and to facilitate the preparation of subsequent project-specific NEPA and SEPA documents through the use of"tiering" or "phasing." The origin of this restoration plan and EIS was an Ecosystem Restoration Study (ERS) conducted as a part of the Corps' Ecosystem Restoration Project. Restoration features at sixty-seven projects in the basin were developed and evaluated to determine the most cost effective and beneficial plan to recommend for restoration of the basin ecosystem. The recommended plan will implement a combination of 45 project-specific and programmatic restoration measures throughout the basin, one of which is the Upper Springbrook Creek Channel Realignment and Rehabilitation. This recommended National Ecosystem Restoration (NER) Plan was selected based upon cost effectiveness and incremental cost evaluation of each alternative's costs and environmental outputs. The recommended NER Plan restores aquatic and terrestrial ecosystem continuity and connectivity and addresses all limiting habitat factors for threatened and endangered salmonids within the basin. The purpose of this tiered Environmental Assessment is to provide information to the public about the project's environmental effects and to solicit public comments on the proposed action. After receiving comments, if the Corps determines that the project will have no significant effects, a Finding of No Significant will be signed and the environmental review process will conclude. 1.1 PROJECT LOCATION AND SETTING The project is located in the City of Renton adjacent to South 55th Street just west of highway 167, in township 23 north, range 5 east, section 31 (Willamette Meridian) in the Green River Basin. The project area encompasses a I 00 foot wide easement from the road by 950 foot long section of stream nestled between the South 55th Street culvert on the upstream end and the highway 167 culvert on the downstream end totaling 2.18 acres (see Figure 1). The project is bordered to the north by a forested wetland owned by Springbrook Apartment Investors, LLC (along with the 100 foot easement), and to the south by South 55th Street, with a private residence on the south side of the road. The property slopes northward and consists primarily of category 2 forested wetland according to the Washington State Department of Ecology's Wetland Rating System (see appendix B for the rating from). Along the southern border, where the stream channel resides, there is a dense overgrowth of invasive, non-native Japanese knotweed and Himalayan blackberry. Larger trees become more prevalent away from the road and the density of the invasive species decreases. 2 Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 1.2 PROJECT PURPOSE AND NEED The overall objective of the Green-Duwamish Ecosystem restoration project is to restore significant ecosystem function, structure, and dynamic processes that have been degraded within the river basin. To accomplish this objective, the following basin-wide restoration goals were identified: • Improve the physical nature of existing degraded habitat. • Improve existing ecosystem functions and values. This includes improving riverine processes where reasonable. • Address important factors limiting habitat productivity. In the lower and middle basins of the Green River conifer vegetation has been nearly eliminated and replaced with pavement and development, particularly in the lower basin. Vegetation that still exists is dominated by deciduous trees and shrubs, some of which are aggressive invasive species. This lack of native vegetated cover and encroaching urban and suburban development has lead to degraded in-stream habitat in both the mainstem Green River and its tributaries without any functional riparian buffer. Currently, the creek is devoid of complexity or refuge for Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 3 juvenile salmonids due to channel straightening and lack oflarge wood recruitment providing minimal opportunities for salmonids to spawn and rear, as well as poor conditions for other aquatic species. In addition, stormwater in the basin enters the rivers and streams via the extensive amount of imperious surface, thus leading to poor water quality. The purpose of the Upper Springbrook Creek is to increase channel diversity (large woody debris, riffle and pool habitat, and suitable substrate for spawning coho) and improve the quality of stream-side vegetation to increase habitat quality for aquatic biota, and particularly, spawning and rearing habitat for salmonids. In addition, moving the stream away from the road will create a vegetated buffer that will absorb the stormwater run-off from South 5 5th Street 1.3 AUTHORITY Section 306 of the WRDA of 1990 authorized the Secretary of the Army to include environmental protection as one of the primary missions of the Corps. Authorization for the Green/Duwamish River Basin Ecosystem Restoration Project, General Investigation (GI) study was provided under Section 209 of Public Law 87-874, Puget Sound and Adjacent Waters. Congress specifically authorized the Green/Duwamish River Basin ERP in Section 10 I (b )(26) of WRDA 2000. This project is a separable element of the Green/Duwamish ERP. The Green/Duwamish ERP gained construction New Start capability in the Water and Energy Act of 2003. The City of Renton is the non-Federal sponsor for the Upper Springbrook Creek Channel Realignment and Restoration project evaluated in this document. The Corps and the City of Renton have cooperated in regular interagency meetings from which the objectives for the proposed restoration work were developed. 1.4 ASSOCIATED STIJDIES AND REPORTS General information regarding the Green/Duwamish River basin and its associated existing conditions, fish and wildlife populations, and potential impacts on federally listed endangered or threatened species is adopted in this document by reference to the: • Final Programmatic Environmental Impact Statement and Restoration Plan (FPEIS) for the Green/Duwamish River Basin Ecosystem Restoration Project, prepared by the Seattle District Corps (Corps) and King County DNRP in November 2000. • Green Duwamish Ecosystem Restoration Study, Final Feasibility Report, prepared by the Seattle District Corps, October 2000. • Programmatic Biological Assessments for Green/Duwamish Ecosystem Restoration Project, King County, Washington. Separate documents were prepared for species under National Marine Fisheries and US Fish and Wildlife jurisdictions for the Seattle District Corps by Jones & Stokes, June 2000. • Habitat Limiting Factors and Reconnaissance Assessment Report, Green/Duwamish and Central Puget Sound Watersheds (WRIA 9 and Vashon Island), Washington Conservation Commission and the King County Department ofNatural Resources, 2000. Final Envirorunental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 4 • Near-Term Action Agenda for Salmon Habitat Conservation, Green/Duwamish River and Central Puget Sound Watershed, Water Resource Inventory Area 9, May 2002. • Record of Decision (ROD) for the Green\Duwamish Ecosystem Restoration Project, Washington, 3 0, April 2 002 2. ALTERNATIVES CONSIDERED In order to comply with the National Environmental Policy Act (NEPA), CEQ rules, and Corps regulations, the Corps performed an analysis of potential alternatives to meet the purpose and need of the project. The programmatic Green/Duwamish EIS analyzed the following alternatives: No Action, Multi-Species Approach (designed to maximize benefits to multiple species offish and wildlife), and Single Threatened Species Approach (focusing on habitat improvement for Chinook salmon). Three alternatives were evaluated under the latter two alternatives including: Ecosystem/Habitat Forming Method, Engineered Design and Constructed Habitat Method, and Integrated Method. The selected alternative was the Multi-Species Approach with and Integrated method. For the Upper Springbrook Project, the Corps evaluated the no-action alternative as well as two alternatives for restoration of the site. The two alternatives differed in how they will contain flood waters and minimize stranding of juvenile coho, given the downhill slope to the north of the realigned channel. These alternatives are listed below. 2.1 THE NO-ACTION ALTERNATIVE Under the no-action alternative, the creek would likely remain a roadside ditch that is overgrown with invasive species like Japanese knotweed and Himalayan blackberry with little to no functional value for aquatic species. The upstream culvert under South 55th Street would stay as is making it difficult for migrating salmonids to pass, and causing continuous scour of the channel on the downstream end. In addition, the creek would continue to receive stormwater runoff and pollution during rains events from South 5 5th Street. 2.2 ALTERNATIVE 1 -Channel Realignment with Bioengineered Features to Minimize Bank Overtopping (Preferred alternative-see Appendix A for projects plans) 2.2.1 Channel Alignment The new channel alignment would be approximately 970 feet long. The cross-sectional geometry would be trapezoidal with 3: 1 side slopes, with a 6-foot bottom width, and an average depth of 1.5 feet. The channel would be over-excavated to allow for the placement of imported 6-inch minus gravel substrate along the channel bottom to provide a substrate that is suitable for instream habitat. The planform of the channel would be sinuous following existing low topography within the JOO-foot wide drainage easement. The new channel alignment gradient (slope) would be approximately 1.4 percent. Plan sheets C2 through C6 show the proposed channel design details. Disturbance area include 0.19 acres where the new channel would be located, a 0.03 acre staging area located on the upstream end, and a 0.01 acre area located on the downstream end (see plan sheet C6). Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 5 Approximately 1077 cubic yards of material would be excavated, of which 506 cubic yards would be over-excavated material that is then backfilled with 6 inch minus gravel. All but I 00 cubic yards of this material would be disposed of off-site at an appropriate location. The remaining 100 cubic yards of material would be used on site for floodplain plantings (see section 2.2.3 for details). Excavation would be done using two teams with a tracked excavator and tracked dumper: one on the downstream end and one on the upstream end both progressing towards the middle. Most material would be hauled out using newly excavated channel as an "access road". Areas disturbed by construction of the channel would be covered in coir fabric to aid in short-term stabilization. Long-term stabilization of the channel would be established by riparian plantings which would benefit from the coir fabric placement. The connection of the new channel would begin at the bottom elevation of the upstream pool at South 55th Street and continue downstream. This pool elevation would establish the elevation of the upstream connection between the new channel and the existing stream. The existing channel would be backfilled at the upstream end with 19 cubic yards of material in order to direct flows to the new channel and to reduce the likelihood of an avulsion of the proposed alignment back to the former ( existing) channel. Less than 5 cubic yards of material would be left in place at the upstream end of the new channel to minimize the potential inflow of water from the existing channel, which would be undisturbed during this process. This material would be removed sequentially when flow is diverted to the proposed channel (see section 1.6.4 on the replacement culvert for details). On the downstream end, the new channel alignment would meet the existing channel approximately 80 feet upstream of the Highway 167 culvert before the existing channel enters property owned by the Washington State Department of Transportation (WSDOT, 2001). A small strip of the existing bank that lies between the existing and new channel would be left in place to prevent backwatering from the existing channel. This strip would be removed, likely with a hand shovel, immediately before flow diversion into the new channel. 2.2.2 Placement of Large Woody Debris (L WD) Placement oflarge woody debris would increase hydraulic variability, promote accumulation of other debris, and enhance fish habitat by providing holding areas with cover and refuge, aeration of surface water, and localized scour and deposition of channel material (microtopography). Spacing of logs would be approximately 22 pieces every I 00 meters. Placing the logs would involve attaching the wire rope to a mechanical duckbill soil anchor, driving the anchor(s) below the channel bottom to a design depth, load locking the anchor and proof testing to a specified load, drilling the log(s), and securing the wire rope to the log(s). In an effort to minimize the travel required for the machinery and to minimize disturbance to the site, channel substrate placement and L WD placements would be done in sequence immediately following the excavation of the channel. Placement ofL WD in the proposed channel would include three configurations (plan sheets C8-9 show details on L WD design): Type 1 is a single log configuration that involves placement of the log in the middle of the channel with its rootwad facing upstream. A shallow trench would be excavated to place the log with approximately the top one-third diameter of the log above final grade. One mechanical soil anchor, installed into the channel subgrade and affixed to the bole downstream of the rootwad mass, would stabilize the log. During placement of the Type I logs a small pool would be Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 6 excavated around and underneath the rootwad. The pool would be lined with imported channel sediment. Type 2 is a single log configuration that would be placed on alternating channel banks. The log bole would be buried into the bank a minimum of 2/3 its length with the top of the log flush with the top of the bank. One mechanical soil anchor, installed into the bank subgrade and affixed to the bole behind the rootwad mass, would stabilize the log. During placement of the Type 2 logs a small pool would be excavated around and underneath the rootwad. The pool would be lined with imported channel sediment. The excavated sediment would be placed as a bar deposit immediately downstream of the L WD placement. Type 3 is a multiple-log bank stabilization structure along the outside bends of the right bank in the new channel. Logs with rootwads would be placed perpendicular to flow at the top of the right bank with rootwads protruding into the channel and the pole ends buried into the right bank. Log poles would be placed parallel to the channel between the perpendicular logs. The logs would then be tied together using wire rope to create a continuous structure. Mechanical soil anchors would be installed into the bank subgrade and affixed to the structure minimizing the likelihood of the structure becoming mobilized. During placement of the Type 3 configurations a pool would be excavated around and underneath the rootwads. Topsoil and vegetation removed for placement of the logs into the right bank would be set aside and replaced following backfill of the logs. 2.2.3 Bioengineered Floodplain Improvements Due to the existing floodplain topography and fixed invert elevations of the upstream and downstream culverts, the channel depth is limited to only 1.5 feet, which would not contain peak flow discharges. Preliminary model results of the proposed conditions indicate overtopping of the banks above and including the I-year recurrence flow throughout a majority of the project reach. Overtopping of the new channel banks is undesirable because it may potentially allow for the stranding offish within the adjacent floodplain, as well as contribute significant volumes of water to No Name Creek, a tributary down-gradient (north) of the project site that has been known to cause flooding concerns (DEA 2001). These same concerns are also associated with the existing conditions of the channel reach, however the proposed alignment may increase the potential for bank overtopping. To minimize these risks floodplain logs would be placed along the north extent of the project area to serve as a natural berm (see plan sheet C13 for details). The logs would be placed horizontally, partially overlapping by approximately 5 feet on either end, and partially buried up to one-half the diameter of the log. Sources of these logs would come from both off-site sources and trees that need to be removed due to channel excavation. Placement of the logs in the floodplain would maximize the potential of flow containment within the proposed floodirlain; larger diameter logs would be placed in the lowest elevation locations in the floodplain and smaller diameter logs would be placed in the higher elevation locations to match the target water surface elevation (WSE) in the proposed condition. Offsetting the logs from the bank would allow floodplain connectivity to the extent possible, while retaining flows in the vicinity of the proposed channel. Live stake willow plantings would be placed adjacent to the proposed floodplain log placements. Approximately I 00 cubic yards of material from the channel Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 7 excavation would be placed along the willow stakes to encourage growth. The plantings would likely not have a significant effect immediately; however, over the long term as the plantings become rooted and the foliage establishes, riparian conditions and floodplain stability would become increasingly enhanced. The established plantings would effectively create a porous wall that would diffuse stream energies during higher flows, while minimizing fish stranding yet allowing for some flow to enter the floodplain. The plantings span the entire length of the proposed floodplain log placements, a distance of approximately 775 linear feet. The spacing for the plantings is proposed for 1 foot on center (O.C.) on both sides of the log placements, with plantings on one side of each log offset I foot from the plantings on the opposite side. As with the instream large woody debris, floodplain wood placement would be done in sequence immediately following the excavation of the channel. Areas disturbed by the use of machinery for the placement of floodplain logs would be temporarily stabilized with the use of straw, coir fabric, or other measure. 2.2.4 Replacement of Culvert on South 55th Street The existing 30-inch diameter corrugated steel culvert that runs underneath South 55th Street at the east end of the project would be replaced as part of the project. The replacement culvert would be constructed west of and parallel to the existing culvert. Construction of this replacement culvert is expected to occur simultaneously with the excavation of the channel, but would ultimately be at the discretion of the contractor. The 46 foot long, 10 foot wide, 4 foot high replacement box culvert would meet the requirement of the WDFW Design of Road Culverts for Fish Passage, 2003 (Culvert Design Manual) and the King County Surface Water Design Manual, 2005 (SWDM). The culvert would have a slope of 1.82 percent with 14.5 inches of gravel placed on the bottom. A low flow channel would be provided by alternating the locations oflarger rock clusters along the culvert sides. Additionally, one large rock sill and two log sills would provide grade control and encourage the development of small pools within the culvert at low flow. The placement plan for sediment in the culvert is shown on plan sheets CI0.1-10.4, Cl I, and C12. The substrate would be placed using an excavator, by hand or by other means as necessary. Log sills would also be placed within the culvert and would be placed by hand or by other means necessary. Approximately 250 cubic yards of material would be excavated to construct the culvert. Construction of the replacement culvert would require the use of heavy machinery and would involve the removal of a section of the asphalt roadway, shoulders, and road subgrade. The removal would affect an area approximately 15 feet wide by 50 feet long and extends the entire width of the roadway. Concrete rubble and other debris present in the existing channel prior to construction would be removed and disposed of properly. Prior to commencing culvert replacement, creek flow would need to be temporarily routed outside of the replacement culvert footprint and into the existing channel. This diversion of creek flow would be achieved with the use of flexible high-density polyethylene (HDPE) pipe that is capable of conveying the entire creek flow during typical summertime flows. If flows exceed the water capacity of the pipe then all work would cease until flow could be contained. In addition to the temporary pipe, a series of temporary in-stream revetments would be necessary to isolate creek flow, both upstream and downstream of the existing culvert, for installation of the replacement culvert. Sequencing of Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 8 events for construction of the replacement culvert would include (see plan sheet C7 for more detail): 1. Install temporary fish exclusion screens upstream of the culvert replacement area and downstream of confluence of existing and proposed channels. 2. Excavate a trench across the road cut and install temporary piping at the upstream end to contain all creek flow through the culvert replacement area and beneath the upstream temporary access route. Install temporary piping at the downstream end for the temporary access route. 3. Establish an access route across both the upstream end and downstream end of existing channel by backfilling the bypass pipe and existing channel (pipes would empty on the downstream end of both access routes). 4. Commence the road cut. The road would be excavated along the replacement culvert alignment to the footprint and elevation suitable to construct the replacement culvert to its design elevation. Shoring and trench protection would be employed as necessary. 5. Demolish, remove, and dispose of the existing culvert, construct and install new culvert, and install in culvert features. 6. In preparation ofrouting the creek through the new channel, excavate a shallow pool just upstream of confluence with new and existing channel. 8. Excavate a small trench around the upstream end of temporary bypass pipe to allow flow through the replacement culvert. 9. Commence flow ramping: As creek flow is introduced to the new channel the sediment laden water would be pumped from the pool described in #6 into the floodplain. Flow would be ramped up as turbidity decreases, Once the turbidity decreases below the state standards Remove small strip of existing bank at the confluence of the existing channel and downstream end of the new channel. 10. Perform fish rescue and recovery as necessary. 11. Remove the temporary flow bypass pipes after flow is fully transferred to new channel. 13. Install headwalls and wingwalls. 12. Repair the road cut according to the applicable jurisdictional standards and requirements. Maintenance of the culvert may be required to prevent erosion on the west bank of creek upstream of the culvert and to maintain in culvert features. Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 9 2.2.5 Decommissioning of the Existing Channel While the existing channel would no longer convey flows from Upper Springbrook Creek, the channel would continue to collect and convey the following sources of flow: • Surface water runoff from South 55th Street which is likely laden with pollutants. • Partial surface water runoff from areas between the existing and new channels • Flow through an existing culvert (Existing Culvert 2) located at the middle of the project (under South 55th Street) that collects runoff in a roadside ditch approximately 400 linear feet in length, as well as a minor tributary that flows into Upper Springbrook Creek from the south • Surface water runoff from areas south of South 5 5th Street • Groundwater flow The existing channel north of South 55th Street would remain undisturbed except for two improvements: 1) a fill of the channel at the upstream end; and 2) planting of the remaining channel between the fill area and Existing Culvert 2, where tributary flow would continue to be conveyed through the former main channel from this point downstream. Proposed planting of the existing channel includes various fast growing native species. These plants would provide naturally occurring treatment (filtration) of the remaining surface flow, by absorbing the water and associated pollutants into their tissues. 2.2.6 Riparian Plantings Planting would occur in the fall following the completion of construction. Prior to all planting, all weeds, including Japanese knotweed and Himalayan blackberry, would be removed from the project site, and a 6-12 inch layer of mulch would be placed in areas to be planted. Emergent plants would be planted directly in the stream beds in and around wood placement, where pools are expected to form. Willow and dogwood lifts would be planted along both banks for the length of the stream. A mixture of native trees and shrubs would be planted in areas that have been disturbed by construction, and areas were invasive weeds have been removed (see table I for a detailed list of plants). In addition to this proposed list, a variety of other species such as salmonberry, alder, cottonwood, dogwood, willows (Salix spp.), and piggyback plant are expected to colonize the area, as seed sources are present on site. Irrigation and invasive species control would take place for five years following planting. Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 T bl 1 R. a e ,panan PI ti ·thN Ch an n2s m e ew anne Location Species Spacin2 Size Within the littoral zone C arex aurea (sedge) of the stream bed Carex hendersonii (sedge) 10 inches Plugs Carex lenticularis (sedge) adjacent to pools Carex stipata (sedge) Scirpus microcarpus or acutus (bulrush) Along the bank from Salix sitchensis (willow) I foot (3/1 OHW to 4ft above Salix lasiandra (willow) salix to stakes OHW (approximately 3 lifts) Salix scouleriana (willow) comus) Cornus sericea (redosier dogwood) Populus balsamifera (cottonwood) Interspersed along the Fraxinus latifolia (Oregon ash) IO feet riparian zone of the Picea sitchensis (sitka spruce) stream in both Thuja p/icata (Western red cedar) 1-2 gallon disturbed areas and areas where invasives Rosa pisocarpa ( cluster rose) have been removed Rhamnus purshiana (cascara buckthom) 4 feet Physocarpus capitatus (Pacific ninebark) Maintenance and monitoring would be required for site plantings, details regarding plant monitoring can be found in Appendix C, Restoration Maintenance, and Monitoring Plan. 2.2.6 Construction Timing and Erosion Control Construction of this project is scheduled for the summer of2011 and expected to take approximately three months. Five eight hours days are the anticipated work hours. All in-water work would occur within the fish window (July 1-September 30) established by the Washington Department of Fish and Wildlife. Erosion and sedimentation during construction activities would be minimized by limiting the amount of disturbance to the creek channel, banks, and the top of slope. In order to minimize the potential for erosion and transport of sediment into the creek system, the following measures would be implemented: • A silt fence would be installed to the extent shown on the plans to minimize transport of sediment beyond the active construction area, and aid in marking access routes and clearing limits. Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 • The use ofrock check dams to reduce flow velocity in steep slope drainages and/or straw bale dams to filter sediment in low-velocity, low-flow drainages. • Clearing limits would be marked and visible during construction to reduce impacts and disturbance within the project area. • Rock construction entrance(s) would be installed to minimize the transport of sediment from the project area onto street surfaces, and/or equipment washing stations located near surface streets to remove sediment from equipment prior to movement of equipment onto surface streets, and/or use of street sweepers or hand sweeping of surface streets to remove sediment and debris transported off site. • All efforts would be made to locate storage and staging areas in flat areas above the ordinary high water line with appropriate erosion and sediment control measures, such as gravel pads. • The number of trips made through the project site by heavy equipment would be minimized. • Following construction completion, all disturbed areas that result in bare earth surfaces would be covered with straw and/or coir fabric to reduce the potential for erosion and sediment transport until the areas are planted in the late fall. • Excavation requiring the temporary removal of top soil and usable vegetation within the channel would be set aside from other excavation spoils and be used to top-dress bare-cut surfaces following grading work completion. • Revegetation of all disturbed areas would occur in the fall following the construction completion. 2.3 ALTERNATIVE 2 -Channel Realignment with a Berm to Contain Bank Overtopping All elements of alternative 2 are the same as alternative 1, with the exception of the use of bioengineered features for floodplain improvements proposed in alternative 1. Alternative 2 proposes to construct a 900 foot long, six foot wide earthen berm west of the new channel to contain peak flow discharges and minimize stranding. While this alternative may insure less of a risk as it is a more solid structure, it was eliminated due to the associated environmental effects and additional compensatory mitigation required by the Washington Department of Ecology that will arise from the additional placement of fill in a forested wetland, and therefore, this alternative was not considered for impacts analysis. 3. EXISTING CONDITIONS Characteristics of the existing environment have been addressed in detail within a number of documents previously prepared as part of the Green/Duwamish River Basin Restoration Project. Characteristics of the existing environment that are specific to the lower Duwamish River and the proposed project site are described in detail below based on reconnaissance work and review of available documentation. Rather than repeating information for the general Green/Duwamish River system here, that information is incorporated largely by reference to the documents listed below: Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May2010 • Final Programmatic Environmental Impact Statement and Restoration Plan (FPEIS) for the Green/Duwamish River Basin Ecosystem Restoration Project, prepared by the Seattle District Corps and King County DNRP in November 2000. • Programmatic Biological Assessments for Green/Duwamish Ecosystem Restoration Project, King County, Washington. Separate documents were prepared for species under National Marine Fisheries and US Fish and Wildlife jurisdictions for the Seattle District Corps by Jones & Stokes, June 2000. • Seattle's Urban Blueprint for Habitat Protection and Restoration: Review Draft, prepared by the City of Seattle's Salmon Team, June 2001. • Habitat Limiting Factors and Reconnaissance Assessment Report, Green/Duwamish and Central Puget Sound Watersheds (WRIA 9 and Vashon Island), Washington Conservation Commission and the King County Department of Natural Resources, 2000. • Near-Term Action Agenda for Salmon Habitat Conservation, Green/Duwamish River and Central Puget Sound Watershed, Water Resource Inventory Area 9, May 2002. 3.1 PHYSICAL CHARACTERISTICS The history and physical characteristics of the Green/Duwamish River basin is described in detail in Sections 3.1 and 3.2 of the FPEIS (USACE and King County DNR 2000). A synopsis of physical characteristics and historic conditions relevant to the proposed restoration project site is presented below. The project is located in the City of Renton in a heavily sub-urban and urbanized area. The creek where the project will take place is actually a 1.2 mile unnamed tributary of Springbrook Creek (stream number 0020, WDFW 1975). It originates roughly 0.60 miles upstream from the project location from two tributaries in a fairly steep cascade area referred to as Springbrook Springs (Figure 2). These two tributaries join just upstream of the project location flowing north before making a 90 degree turn at South 55th Street (where the project site is located) flowing west under Highway 167. It joins with Springbrook Creek 0.2 miles west of Highway 167. Springbrook Creek then joins with Mill Creek and meanders north through the City of Renton before emptying into the Black River Marsh north oflnterstate 405. The Black River Marsh is a small marsh, remnant of the historic Black River, which feeds into the Green River. The section of creek that is proposed for realignment flows year-round with an average depth of 1.3 feet and an average width of 6.5 feet from top of bank to top of bank. Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 3.1.1 Geology and Soils The project area is located in the transition zone of the higher gradient foothills of the Cascades to flatter, more gently sloping landscape typical of large river floodplains. Near South 55th Street, where the current channel is located, the soil is composed of Alderwood gravelly sandy loam (basalt till with volcanic ash) with a 6-15 percent slope. The Alderwood soil series is not classified as a hydric soil. Farther away from the road the soil is mixed alluvial sand (a mix of sand, loamy fine sand, and gravelly sand), likely remnant of the historic stream channel. Towards the downstream end of the project soils are Snohomish loam silt, which is typical of flood plains. At the headwaters of the creek, less than one mile upstream, soils are Alderwood (basal till with volcanic ash) and Kitsap (Lacustrine deposits with a minor amount of volcanic ash); both are characterized as very steep (USDA Websoil survey, 2009). 3.1.2 Hazardous and Toxic Materials A Preliminary Assessment Screening (PAS) was performed by the Environmental Engineering and Technology (ET) Section of the Corps to determine whether any hazardous or toxic material is present on or around the site that could affect project activities (USACE, 2008). The PAS did not identify any recognized environmental conditions at the property. The term 'recognized environmental conditions' means the presence or likely presence of any hazardous substances or petroleum products on a property under conditions that indicate an existing release, a past Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 release, or a material threat of a release of any hazardous substances or petroleum products into structures on the property or into the ground, ground water, or surface water of the property. Washington Department of Ecology's environmental database was reviewed for hazardous waste generators, facilities, underground storage tanks, and leaking underground storage tanks in the area. According to the Washington Department of Ecology (WDOE) the only hazardous site near the project vicinity that may affect the site is located less than one mile upstream, only 200 feet from the stream. Based on the PAS, there is no evidence that this upstream site is currently or has in the past affected the project site. There are many other sites that are within a mile of the project location, however, most of them (in the Kent industrial zone) are down grade from the site and are not expected to impact the property (WDOE, 2008a). 3.1.3 Hydrologic Regime The historic and current hydrological characteristics of the Green/Duwamish River basin are described in detail in Section 3.3 of the FPEIS (USACE and King County DNR 2000). Upper Springbrook Creek originates from two channels located in an area referred to as Springbrook Springs that join less than a half of a mile upstream of the project site. The project area starts at South 55th Street, where a 30 inch culvert crosses beneath the road, limiting both hydraulic flow and transport of sediments. Residents have reported flooding upstream of this culvert. From this culvert to the downstream extent of the project limits, the existing channel is a mostly linear, uniform roadside swale that runs parallel to South 55th Street on the north side. The stream bottom is approximately 4 feet wide with an average gradient of 1.3 percent. Low gradient glides are the predominant habitat type, with pools lacking in the system (WDOT, 2001). The project ends at a five by ten foot box culvert underneath Highway 167. Due to its proximity to South 55th Street, it is likely that this section of stream, as well as downstream areas, experience more "flashiness" or higher peak flows during heavy rain events then that of a stream with a sufficient riparian buffer. Flow events for this portion of stream are summarized in Table 2 (WDOT, 2001). Tab 2 D' h le . 1sc ar!!e at loner ;orm!!broo u s kCreek Flow Event Discharge (cubic feet ner second) 1-vear 48 2-vear 70 5-vear 84 10-vear 88 25-vear 99 50-vear 110 100-vear 121 North of the existing channel is a class 2 forested wetland according to the Washington State Wetland Rating System (see appendix B for the formal report and rating form). A delineation conducted in early September found unambiguous wetland indicators (including standing water) Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 at both ends of the project site. The center area, while dominated by hydrophytic vegetation, had more marginal soil indicators. This may be due to presence of sand dominated, faster draining soil in this area, possibly the result of a historic stream channel location. However, the landscape position of the site and the presence of unambiguous hydrology during the dry season both indicate the central area of the site to be wetland. Therefore, the entire project site was concluded to be wetland (see appendix B for wetland delineation and rating). Evaluation of ground surface data indicate that the ground surface north of the existing channel drops in elevation with increasing distance from the existing right channel bank (Figure 2). When the stream overtops, its flows move northward through the adjacent forested wetland toward the City of Renton and ponds on the west side of SR 167 before eventually flowing north to No Name Creek. This area is not mapped as a FEMA flood hazard area (WDOT, 2001). 3.2 WATER QUALITY The historic and current water quality characteristics of the Green/Duwamish River basin are described in detail in Section 3.4 of the FPEIS (USACE and King County DNR 2000). This area of the Green Duwamish Basin (Upper Springbrook Creek) is designated for the following uses: spawning and rearing, primary recreation, domestic water, industrial water, recreational water, stock water, wildlife habitat, harvesting, and aesthetics. Because this project site is a small tributary stream, there is little water quality data available for this specific location. However, it's possible that water quality standards could be exceeded periodically for certain pollutants due to the stream's proximity to the road. Downstream of the project site, mainstem Springbrook Creek is on Washington Department of Ecology's 303d list (polluted waters) for fecal coliform and dissolved oxygen, and is also listed as a water of concern for temperature and Bis (2-Ethylhexyl) phthalate near its confluence with the Black River Marsh (WDOE, 2008b). 3.3 VEGETATION The historic and current characteristic vegetation of the Green/Duwamish River basin are described in detail in Section 3.6 of the FPEIS (USACE and King County DNR 2000). Historically, conifers dominated the lowland forests of the Green River Valley. Currently, nearly all of these coniferous forests have been replaced by both residential and commercial development in the valley. Much of what vegetation remains is dominated by deciduous trees and invasive shrubs. Vegetation directly adjacent to the current channel consists of dense stands of Japanese knotweed (Polygonum cuspidatum and Polygonum bohemicum) and Himalayan blackberry (Rubus discolor), with occasional interspersed willows (Salix spp.), making it difficult to view and access the channel. Within the channel, reed canary grass (Phalaris arundinacea) is prevalent along with Japanese knotweed shoots. Vegetation on the south bank of the stream is limited to a narrow margin of invasive shrubs between the South 55th Street and the stream edge. Behind the stream, to the north, is a forested wetland composed mostly of deciduous species, like alder (Alnus rubra) and cottonwood (Populus balsamifera), with interspersed cedar (Thuja plicata). Understory vegetation includes salmonberry (Rubus spectabilis), dogwood (Camus sericea), skunk cabbage (Lysichiton americanus), and piggyback plant (Tolmiea menziesii). Final Environmental Assessment Upper Springbrook Creek Channel Realigoment and Rehabilitation May 2010 3.4 AQUATIC BIOTA 3.4.l Fish The historic and current characteristic fish communities of the Green/Duwamish River basin are described in detail in Section 3.5 of the FPEIS (USACE and King County DNR 2000). Due to the size of the stream and its separation from the main stem Green River, the only species of anadromous salmon that are known to be present in this tributary of Springbrook Creek are coho salmon (WDFW, 1975, 2002). These coho spawn in the Green River Basin between October and December. After hatching, the juveniles will rear in fresh-water for 15 months before migrating to the ocean as smolts in the spring. They will then spend two growing seasons in the ocean before returning to freshwater to spawn as three year-olds (NMFS, 2009). Large numbers of hatchery-reared coho have been released into the Green River system since the early 1900s, therefore the coho that utilize this tributary are of a mixed hatchery and native origin (WDFW, 2002). Resident species of fish in the Springbrook system include cutthroat tout, rainbow trout, threespine stickleback, pumpkinseed sunfish, speckled dace, lamprey (/ampetra spp.), and sculpin (Cottus spp.) (Harza, 1995). Fish habitat within the channel is in a highly degraded state due to the straightened nature of the channel, lack of native overhanging vegetation, poor pool-riffle structure, and high peak flows it receives from surface water runoff from South 55th Street, all of which limit the amount ofin- stream micro-habitat and refuge. Although there are some areas where suitable spawning gravel for coho exists within the current channel, it is likely hatching success and juvenile survival is limited by the factors discussed previously. The culvert underneath South 55th Street at the upstream end of the project site is a fish barrier, especially for juveniles, as its downstream invert is perched approximately three feet above the channel bed elevation, limiting access to higher quality habitat located upstream of the project area (Figure 3). In addition, downstream habitat consists of a series of channelized canals and ditches that weave through high density commercial and industrial areas of Renton and are essentially devoid of any suitable fish habitat. The Black River Marsh pump station is located 800 feet upstream of the marsh's confluence with the Green River. Although the pump station has a fish ladder for fish migrating upstream and a airlift bubble system for juvenile outmigration, it likely limits anadromous fish movement in and out of the Springbrook system. Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 Figure 3. South 55th Street Culvert 3.4.2 Benthic Invertebrates A benthic invertebrate survey was done using Hess sampler methodology in the fall of 2008. Species diversity and abundance was relatively low, with a high proportion of tolerant oligochaete worms, reflecting a stream in a degraded state. Other invertebrates found in the samples include fly and midge larvae, beetle larvae, caddisfly larvae, mayfly larvae, stonefly larvae, thread worms, flat worms, and fingernail clams. 3.5 WILDLIFE The historic and current characteristic wildlife communities of the Green/Duwamish River basin are described in detail in Section 3.7 of the FPEIS (USACE and King County DNR 2000). Common urban wildlife such as coyotes, Columbian black-tailed deer, beaver, raccoons, opossums, rats, mice, and voles are likely to be found in the project area. Numerous bird species including white-crowned sparrows, fox and song sparrows, common yellowthroat, yellow warbler, northern flickers, American robins, American crows, Stellar blue jays, spotted towhees, red-winged blackbirds, dark-eyed juncos, black-capped chickadees, brown creepers, woodpeckers, northern oriels, flycatchers, belted kingfishers, American dippers, American goldfinches, Bewick's and winter wrens, solitary and warbling vireos, and warblers are likely to utilize the riparian areas of the project, particularly the forested portions (Connell, 1993). Birds of prey such as Cooper's, sharp-shined, and red-tailed hawks, and western screech and barred owls can be present in the project area in search of prey. Bald eagle sightings have occurred within close proximity of the project area at both Panther Lake to the southeast and the Black River Marsh to the northwest (WDFW, 2008). Tree frogs and garter snakes may also utilize the site. Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May2010 3.6 THREATENED AND ENDANGERED SPECIES The potential occurrence of federally listed threatened and endangered species within the Green/Duwamish River basin are described in detail in Section 3. 7.2 of the FPEIS (USACE and King County DNR 2000). In accordance with Section 7(a)(2) of the Endangered Species Act of 1973, as amended, federally funded, constructed, permitted, or licensed projects must take into consideration impacts to federally listed and proposed threatened or endangered species. The Corps prepared two Programmatic Biological Assessments (BA) to assess potential impacts of the proposed work on species protected under the Act • one for species under the jurisdiction of the USFWS and one for species under the jurisdiction of NOAA Fisheries. Those BAs covered the federally listed threatened or endangered species listed in Table 3. Since the programmatic consultation has taken place, critical habitat has been established for Puget Sound Chinook and bull trout (NMFS 2005; USFWS 2005), and Puget Sound steelhead have been listed as threatened (NMFS, 2007). The bald eagle has since been delisted. Bald Eagle Delisted Haliaeetus leucoce ha/us Marbled Murrelet Threatened Designated Brach ram hus marmoratus Northern Spotted Owl Threatened Designated Strix occidentalis caurina Gray Wolf Threatened Canis /u us Canada Lynx Threatened L nx canadensis Coastal/Puget Sound Bull Threatened Trout Salvelinus confluentus Puget Sound Chinook Threatened Designated Salmon Oncorh nchus tshaw scha According to the Washington Department of Fish and Wildlife, the only species of salmon present in this portion of Springbrook Creek are coho salmon, which are not a federally listed species. Steelhead in the Green River system utilize the mainstem channel and larger tributaries like Soos and Newaukum Creeks. Chinook salmon do use mainstem Springbrook, but do not travel as far as the project location. Reports of historical bull trout use of tributaries in the lower Green River are rare, and there have been no recent observations (King County CDNR 2000). No bull trout or Chinook salmon critical habitat is designated in the project area. Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 According to the Washington Priority Habitat Database and Washington Gap Analysis wolves, lynx, and grizzly bears are only found on the slopes and foothills of the Cascade Mountains, and there have been no reported sightings within the Puget Sound lowlands. Marbled murrelets and spotted owls also nest in the old growth forests of the Cascades and Olympic Mountains and are not known to be present in Puget Sound lowlands (WDFW, 2008). Therefore, no federally listed ESA species or their critical habitat are expected to occur within the Upper Springbrook project area. 3.7 CULTURAL RESOURCES The existing condition of the site indicates there is a low probability for the project to effect historic properties up to a depth of three feet below the current ground surface. However, given the current understanding of the geological deposits with the general project area and documented rapid accumulation of sediments within the Green River Basin (Forsman et al. 2003), it is recommended any excavation below three feet be monitored for cultural materials for the following reasons: a) Prior Disturbance. In order for an archaeological site to be eligible to the National Register of Historic Places (NRHP) under Criterion D, it must exhibit several characteristics including: stratigraphic integrity, sufficient quantity of archaeological materials and have the potential to yield important information to our understanding of the regional history or prehistory. Stratigraphic integrity, whether vertical or horizontal, can be suggested by the presence of intact features and/or activity areas, or the presence ofa limited range of projectile point styles or other temporally diagnostic artifact types. Historic archaeological sites must retain integrity and have the potential to provide information beyond that which is available in the written documentation or oral histories. Presently, as a result of subsurface investigations the project area lacks sufficient stratigraphic integrity and archaeological materials. However, an understanding of deeper deposits is presently lacking. It is likely the project area has been sufficiently disturbed up to the proposed depth of the proposed project, but this still needs to be confirmed. The Corps has determined this confirmation can be gathered by the monitoring of the proposed channel excavations during the construction phase because the likelihood of discovering archaeological materials is considered to be low. b) Absence ofrecorded historic properties. The Corps conducted an ethno-historic investigation of the project area to determine potential effects of the proposed maintenance work on cultural and religious sites of importance to the Muckleshoot people. Research included a search of the Washington Department of Archeology and Historic Preservation (DAHP) Electronic Historic Sites Inventory Database, archival research and consultation with the Muckleshoot Tribal Historic Preservation Officer (THPO) and cultural advisor. The result of this investigation was the determination that the project is unlikely to have an adverse effect on intact pre-Contact cultural deposits should any exist within the project area of potential effect (APE). Although a number of cultural resources sites are documented within the general vicinity of the project, they are Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 outside of the project APE, as defined. There are no previously recorded pre-Contact or early historic archaeological sites within the project APE. c) There are no historic buildings present or previously recorded in this project area. The Corps conducted a search of the Department of Archaeology and Historic Preservation Electronic Historic Sites Inventory Database, in addition to referencing archival materials and the appropriate municipal records. This research indicated there have been no previously recorded structures in this location. In addition, given the nature of this project there will be no impact to any viewsheds of any recorded historic properties. 3.8 NATIVE AMERICAN CONCERNS The cultural and historic resources of the Green/Duwamish River basin are described in detail in Section 3.16 of the FPEIS (USACE and King County DNR 2000). Site-specific information is presented below. The Springbrook Creek System is within the usual and accustomed fishing area of the Muckleshoot Indian Tribe. The Muckleshoot tribe considers the fisheries resources of the Springbrook Creek/Green River system to be an invaluable resource, and a primary goal of the tribe is to protect and restore each run of fish in its usual and accustomed fishing area. 3.9 LANDUSE The historic and current land and shoreline use of the Green/Duwamish River basin are described in detail in Section 3.11 of the FPEIS (USACE and King County DNR 2000) and in the WRIA 9 Habitat-limiting Factors and Reconnaissance Report (Kerwin and Nelson, 2000) in the section titled "Land Use." A discussion of land use relevant to the proposed restoration project site follows. The City of Renton is designated as an incorporated area according to the King County Land Use Survey (King County, 2009). The property where the project is located is a forested area owned by Springbrook Apartments, LLC and is zoned as residential. A 100 foot easement was granted to the City of Renton by Springbrook Apartments to construct this project. Land use in the City of Renton is dominated by industrial and commercial development with interspersed multi and single family residential development. The project site is bordered to north by a forested wetland, which is part of a narrow vegetated corridor that runs parallel to the eastern side of Highway 167 for roughly three miles, starting at the junction with 1-405. To the south, the forested corridor continues with low density residential development. To the east of this corridor, the landscape is dominated by both multi-and single family residential developments. The project area is bordered to the west by Highway 167, and to the west of this highway the landscape is almost exclusively commercial development (Figure 4). However, the Springbrook Creek Wetland and Habitat Mitigation Bank is located amongst this development, one mile to the northwest of the project site. Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 Figure 4. Land Use Around the Upper Springbrook Creek Project Location 3.10 RECREATION Little recreation exists in the immediate area. There are no trails and the area is densely overgrown with invasive shrubs. The project is also located on a dead end street adjacent to Highway 167 and surrounded by private property. All these factors make access to the site difficult. The nearest source of recreation will be the Green River Trail, located two miles to the west, used for biking and jogging, and Panther Lake, 1.5 miles to the southeast, used for fishing and smallcraft boating (Fishing Works, 2009). 3.11 AIR QUALITY AND NOISE Information characterizing the air quality and noise levels within the Green!Duwamish River basin is described in detail in Sections 3.8 and 3.9 of the FPEIS (USACE and King County DNR 2000). A discussion of current site-specific information relevant to the proposed restoration project site is presented below. In general, air quality in the Puget Sound region is considered to be good. Areas where pollutants originate from are mostly urban where there is a high density of cars, residences, and industry. Sources of these pollutants include car and truck exhaust and smoke from outdoor burning and wood stoves (WDOE, 2009). In 2008, the Puget Sound Clean Air Agency reported that Puget Sound was in attainment for CO2 , N02 , S02, and lead, and the percentage of days air ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~-22 Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 quality was considered to be good in King County was 78%, the percentage of days that air quality was "moderate" was 21 %, and percentage of days where the air quality was considered "unhealthy for sensitive groups" occurred 1 % of the time, likely during times of stable weather when there is an absence of wind. In the winter months, temperature inversions can occur as a result oflow solar heating. During these occasions, high concentrations of pollutants associated with wood burning (stoves and fireplaces) and transportation sources can occur. This condition is intensified by the topography of the valley walls. However, for fine particulate matter (pm 2.5) no exceedances of the federal standards occur in King County. In addition, ozone is a standard that can be exceeded in Puget Sound on hot, sunny days during the summer. In 2006-2008 the Mud Mountain monitor in Enumclaw, King County violated the federal 8-hour ozone standard (Puget Sound Clean Air Agency, 2008). This monitoring stations is located in a rural region; although the precursor chemicals that react with sunlight to produce ozone are generated primarily in large metropolitan areas. Ozone can typically be transported 10-30 miles downwind from the original source (Puget Sound Clean Air Agency, 2008). Primary sources of noise and pollution at the project area come from traffic on Highway 167, located perpendicular to the downstream end of the project site. Noise from South 55th Street is minimal as it is a dead end. 3.12 TRANSPORTATION Information characterizing traffic and transportation within the Green/Duwamish River basin is described in detail in Section 3.10 of the FPEIS (USA CE and King County DNR 2000). A synopsis of site-specific information relevant to the project site is presented below. Traffic within the vicinity of the project occurs along Highway 167, which crosses the stream just downstream. There is minimal traffic on South 55th Street as it dead ends at Highway 167, therefore limiting traffic to a few local residents. 3.13 AESTHETICS Information characterizing visual quality and aesthetic resources within the Green/Duwamish River basin is described in detail in Section 3.13 of the FPEIS (USACE and King County DNR 2000). A discussion of site-specific information relevant to the project site is presented below. There is little aesthetic value to this section of stream due to its proximity to South 55th Street and Highway 167, and its overgrowth of invasive vegetation. The forested wetland is a part of a narrow strip of vegetated land that lies to the east of Highway 167. This "green" corridor is one of only a few in a landscape dominated by urban development. Enjoyment of this corridor is difficult to the west due to the location of Highway 167; however it is visible from the highway. To the east access can be limited due to the placement of private residences and dense overgrowths of blackberry. It is likely that local residents that border this green space enjoy viewing birds and urban wildlife. Final Environmental Assessment Upper Springbrook Creek Charmel Realignment and Rehabilitation May 2010 4. ENVIRONMENTAL EFFECTS OF THE PREFERRED ALTERNATIVE 4.1 PHYSICAL CHARACTERISTICS 4.1.1 Geology and Soils 4.1.1.1 No action Under the no action alternative no impacts to geology and soils will occur. 4.1.1.2 Preferred Alternative Information describing the environmental effects on the topography, geology, and soils of the Green/Duwamish River basin is presented in Section 4.4.1 of the FPEIS (USACE and King County DNR 2000). A discussion of site-specific information relevant to the proposed restoration project site is presented below Under the preferred alternative impacts to geology and soils are expected to be minimal as the footprint of the project is limited to the new channel aligrunent, which will receive spawning gravels for coho salmon and be planted with native riparian vegetation (including 3-6 inches of mulch). Disturbance from construction will be short-term and temporary. Topography of the wetland will change slightly due to the creation of the new stream channel and the construction of a bioengineered berm. Approximately 1077 cubic yards of soil will be excavated to construct the new channel, of 100 cubic yards will be used on the bioengineered berm-the rest will be hauled offsite. There will be a pulse of sedimentation following diversion of the stream into the restored streambed, resulting in short term turbidity increases as the streambed adjusts to the new flow, and localized shifting of sediments will continue sporadically as the new stream recovers and adjusts. Soil erosion control measures should minimize these impacts. Therefore, impacts to geology and soils are expected be insignificant. 4.1.2 Hazardous and Toxic Materials 4.1.2.1 No action There are currently no hazardous or toxic materials on site. Under the no action alternative, conditions are expected to remain unchanged. 4.1.2.2 Preferred Alternative Information describing the environmental effects on hazardous and toxic materials of the Green/Duwamish River basin is presented in Section 4.4.2 of the FPEIS (USACE and King County DNR 2000). A synopsis of site-specific information relevant to the proposed restoration project site is presented below. There is currently no hazardous or toxic material on site. During construction and installation activities, fuels, oils, lubricants, and other hazardous materials will be used. An accidental release or spill of any of these substances could occur. A spill could result in potentially adverse impacts to on-site soils. However, the amounts of fuel and other lubricants and oils will be limited, and the equipment needed to quickly limit any contamination will be located on site. To minimize the likelihood of potential spills and leaks of petroleum and hydraulic fluids during project construction, construction equipment will be inspected daily for leaks and petroleum contamination. Additionally, a spill prevention control and containment plan designed to reduce ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 24 Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May2010 impacts from spills (fuel, hydraulic fluid, etc.) will be in place prior to the start of construction. Finally, the project will not introduce any hazardous materials to the project areas. Therefore impacts to hazardous and toxic materials are expected to be insignificant. 4.1.3 Hydrologic Regime 4.1.3.1 No action Under the no action alternative the channel will remain in its current location, directly adjacent to the road, and the culvert underneath South 55th Street will remain in place. Water will continue to back up upstream of this culvert during heavy rain events due to its constrictive size and configuration. The stream channel will continue to receive stormwater runoff from South 55th Street causing steep peaks in flow during heavy rain events with little area for slow water refuge due to its straightened nature. 4.1.3.2 Preferred Alternative Information describing the environmental effects on the water resources of the Green/Duwamish River basin is presented in Section 4.5 of the FPEIS (USACE and King County DNR 2000). A discussion of site-specific information relevant to the proposed restoration project site is presented below. Under the preferred alternative the hydraulic regime is expected to improve with the replacement of the culvert and the meandering of the new stream channel. Replacing the culvert underneath South 55th Street will increase conveyance and reduce flooding upstream. Meandering the stream will slow down flow at bends. The placement of large wood and plantings will provide areas of slow water by the creation of pools, and minimize bank overtopping. In addition, relocating this section of stream away from South 55th Street will greatly decrease the amount of surface water runoff entering this section of stream, thus decreasing peak flow during heavy rain events. Due to the existing topography of the site, increased flooding to the north could occur during higher flows. However this flooding poses little risk to human development as the area is mostly forested wetland. In addition, the presence of the bioengineered berm should minimize this risk. 4.2 WATERQUALITY 4.2.1 No Action Under the no action alternative water quality will remain as is, in a degraded state from storm- water run-off received from South 55th Street 4.2.2 Preferred Alternative Information describing the environmental effects on the water quality of the Green/Duwamish River basin is presented in Section 4.6 of the FPEIS (USACE and King County DNR 2000). A synopsis of site-specific information relevant to the proposed restoration project site is presented below. Temporary increases in turbidity may result from construction activities. The largest impact will occur during the connection of the relocated channel with a new culvert. In addition, there will be a pulse of sedimentation following diversion of the stream into the restored streambed, resulting in short term turbidity increases as the stream bed adjusts to the new flow. Localized Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 shifting of sediments will continue sporadically as the new stream heals and adjusts. High flows during the winter and spring following construction will continue to mobilize sediments in the project area, potentially contributing to small increases in turbidity over .that normally seen during high flow events. In order to reduce temporary increases in turbidity and potential related effects on juvenile salmonids, all 'in-water' construction work will take place during the established fish window (July 1 -September 30), which is the driest time of the year. Construction techniques, sequencing, and timing will minimize soil disturbance to the extent practical to reduce the generation of turbidity during connection of the new channel to the new culvert. To mitigate turbid flow in the new channel, a temporary shallow trench or pool will be excavated downstream of the confluence of the new and existing channels, where the turbid water will be pumped into the floodplain. Similarly, the design and implementation of the erosion-control and the Storm Water Pollution Prevention (SWPPP) plans will incorporate best management practices (BMPs) such as installation of a silt fence, placement of staging areas in flat areas above the ordinary high water line with gravel pads, minimizing the number of trips heavy equipment makes though the site, and revegetation of disturbed areas to further reduce the duration and magnitude of the temporary increases in turbidity. Turbidity monitoring during construction will ensure that these temporary increases are in compliance with State Water Quality Conditions. Water quality in this section of Upper Springbrook Creek should improve as a result of the project. Stormwater from South 55th Street will no longer run off directly into the creek, and the buffering wetland and planted decommissioned channel will filter pollutants from the runoff before it enters the creek. In addition, as the native trees and shrubs along the stream bank mature, they will shade the stream channel, preventing further increases in water temperature. 4.3 VEGETATION 4.3.1 No Action Under the no action alternative vegetation will remain as is, with dense overgrowths of Himalayan blackberry and Japanese knotweed along the stream, and the forested wetland vegetation will be left intact. 4.3.2 Preferred Alternative Information describing the environmental effects on vegetation in the Green/Duwamish River basin is presented in Section 4.8 of the FPEIS (USACE and King County DNR 2000). A discussion of site-specific information relevant to the proposed restoration project site is presented below. Under the preferred alternative the invasive vegetation along the current channel will be removed and planted with native water tolerant species. Due to the alignment of the new channel through the forested wetland, approximately IO larger alders and understory will need to be removed. The trees that will be taken down will be used to create the planted log berm that will stabilize the bank and decrease the frequency of bank overtopping. Native trees and shrubs will be planted along the stream banks. Temporary impacts to the wetland may result from the staging areas used to access the site and the placement of logs both in-channel and adjacent to the Final Envirorunental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 channel to create the wood berm. Impacts from the staging areas will occur mainly in areas of Japanese knotweed and Himalayan blackberry, and will be returned to their original state (minus the invasive vegetation) following construction. Any impacts to vegetation in the wetland from the construction of the log berm will be compensated by riparian plantings (see plan sheets 27-29 for the planting plan, and appendix C, Draft Restoration, Maintenance, and Monitoring Plan, for details that will ensure planting success). The proposed action is consistent with the Corps requirements of Nationwide Permit (NWP) 27 for stream and wetland restoration activities. Under this permit, compensatory mitigation is not required if the authorized work results in a net increase in aquatic resource functions and values in the project area. While the project will result in impacts to 0.27 acres of the forested wetland (ofwhich 0.19 acres will be permanently lost), the newly constructed streambed will provide enhanced functional habitat value for fish, aquatic invertebrates, amphibians, and other aquatic biota, as well as a similar increase in function and value for mammals, birds, and insects in riparian areas. The plantings will increase the habitat value of the site by creating additional opportunities for foraging, nesting, cover, and refuge for a wide variety of species. 4.4 AQUATIC BIOTA 4.4.1 Fish 4.4.1.1 No Action Under the no action alternative fish communities will continue to experience degraded habitat with lack of channel complexity (due to the straightened channel configuration) and woody debris, poor water quality conditions, and high peak flows due to surface water runoff. 4.4.1.2 Preferred Alternative Information describing the environmental effects on the fisheries resources of the Green/Duwamish River basin is presented in Section 4.7 of the FPEIS (USACE and King County DNR 2000). A discussion of site-specific information relevant to the proposed restoration project site is presented below. Temporary impacts to fish may result during construction, particularly during the connection of the culvert with the new channel. These impacts will be avoided by installing a temporary fish exclusion fence upstream of the new channel prior to the release of water into the new channel to reduce the likelihood of fish migrating into the new channel with inadequate flow depths present. Flow from the existing creek will be slowly and sequentially transferred to the new channel in an effort to closely monitor water quality conditions, stability of the new channel, and to perform fish rescue and recovery within the existing creek. Additional recommendations for procedures to implement during the dewatering phase may arise from consultation with WDFW. However, no significant or long-term negative impacts on fish populations in Upper Springbrook Creek are expected because of the construction activities. Other temporary impacts to fish could arise from elevated turbidity levels. In order to reduce temporary increases in turbidity and potential related effects on juvenile salmonids, all 'in-water' construction work will take place during the appropriate fish window (July 1 to September 30), the driest time of the year. In addition, best management practices such as installation of a silt fence, placement of staging areas in flat areas above the ordinary high water line with gravel Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 pads, minimizing the number of trips heavy equipment makes though the project site, and the revegetation of disturbed areas will reduce the generation of turbidity during construction. In the long term, habitat quality conditions for both anadromous and resident fish are expected to increase greatly. Meandering the stream and the placement of large woody debris will provide pool-riffle structure. The pools will be used as refuge and foraging habitat for both juvenile coho as well as resident fish. Riffles will be utilized for spawning by adult coho as well other fish that are found faster flowing areas, such as sculpin. Diverting the stream away from the road will greatly decrease the amount surface water run-off pollutants fish are exposed to. Streambed gravel will line the channel, providing spawning habitat and better substrate for the production of aquatic insects and other benthic and epibenthic organisms that provide a prey base for juvenile salmonids. Planting the stream banks with native vegetation will provide shading that serves as thermal refuge during wann summer days, as well as a source of organic input for the food chain and insect drop as a direct source of food. 4.4.2 Aquatic Invertebrates 4.4.2.1 No Action Under the no action alternative benthic invertebrate diversity and abundance will remain low due to the degraded in-stream conditions and pollution runoff received from South 55th Street. 4.4.2.2 Preferred Alternative Information describing the environmental effects on the aquatic invertebrates of the Green/Duwamish River basin is presented in Section 4. 7 of the FPEIS (USACE and King County DNR 2000). A discussion of site-specific information relevant to the proposed restoration project site is presented below. All benthic invertebrates within the old channel are likely to be lost due to partial backfilling and diversion of flow into the new channel. It is expected that benthic invertebrates will rapidly colonize the new channel and overall diversity and abundance will increase will be greater than the old channel since there will no longer be exposure to pollutants from runoff the stream receives from South 55th Street . In addition, the newly planted native vegetation and many deciduous trees and shrubs that already exists on site will provide a source of organic input to fuel benthic invertebrate communities. The placement of gravel will provide suitable substrate for benthic communities. 4.5 WILDLIFE 4.5.1 No Action No changes to wildlife use will occur in the area under this alternative. 4.5.2 Preferred Alternative Information describing the environmental effects on wildlife of the Green/Duwamish River basin is presented in Section 4.9 of the FPEIS (USACE and King County DNR 2000). A discussion of site-specific information relevant to the proposed restoration project site is presented below. Wildlife that is foraging or resting in the vicinity of the project at the time of construction may be temporarily displaced due to the noise and movement of the machinery. However, these effects ~~~~~~~~~~~~~~~~~~~~~~~~~~~~28 Fina] Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 will be temporary and displaced animals will likely return to the area after construction is completed. As urban-adapted predators, bald eagles and other raptors that may be foraging over the area are unlikely to be affected by the construction activities as they will focus on other, larger streams in the area. No breeding or nesting areas will be directly impacted, as the construction will take place in mid to late summer. Construction of the restoration site is not expected to result in a long-term reduction in the abundance or distribution of any prey items that local wildlife may be seeking. Planting native trees and shrubs along the stream bank will increase the extent and species diversity in the restoration site by creating additional opportunities for foraging, nesting, cover, and refuge for a wide variety of species. 4.6 THREATENED AND ENDANGERED SPECIES 4.6.1 No Action The degraded condition of the creek will continue to influence downstream conditions for threatened Chinook and steelhead by way of surface water runoff received from South 55th Street. 4.6.2 Preferred Alternative Information describing the environmental effects on threatened and endangered fish species of the Green/Duwamish River basin is presented in Section 4.7.4 of the FPEIS (USACE and King County DNR 2000); the effects on threatened and endangered plant species is presented in Section 4.8.3 of the FPEIS and effects on threatened and endangered wildlife species is presented in Section 4.9.2 of the FPEIS (USACE and King County DNR 2000). The effect determinations made in the Programmatic Biological Assessments for 2the Green Duwamish Ecosystem restoration are listed in Table 4. The USFWS concurred with the determination of "may affect, but not likely to adversely affect" for the bald eagle, marbled murrelet, northern spotted owl, gray wolf, Canada lynx, and bull trout via a concurrence letter dated 27 March 2001 (Appendix D). Similarly, NOAA Fisheries concurred with the determination of "may affect, but not likely to adversely affect" for Puget Sound Chinook salmon via a concurrence letter dated 10 April 2001 (Appendix D). Steelhead have since been listed, but do not occur in the project area. In addition, bull trout and Chinook critical habitat have been designated; however there is no designation in the project area. Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 Table 4. Threatened and Endangered Species Effects Determinations for the Green- D 'hE R uwam1s cosvstem estoration ,f iJil1\1} .-,.··:c ..• 11.;t!,~l;;f J!W? :t.Li!!!Q 90si ;qriticar): :fl~!fr~~tJ~·~tI ::1~!tii~thif ·,. Status,,c ; Habitat,:: Bald Eagle Delisted -Not likely to Yes Haliaeetus leucocevha/us adversely affect Marbled Murrelet Threatened Designated Not likely to Yes Brachyramphus marmoratus adversely affect species or critical habitat N orthem Spotted Owl Threatened Designated Not likely to Yes Strix occidentalis caurina adversely affect species or critical habitat Gray Wolf Threatened Not likely to Yes Canis luvus adversely affect Canada Lynx Threatened -Not likely to Yes L 1Jnr canadensis adverselv affect Coastal/Puget Sound Bull Trout Threatened -Not likely to Yes Salve/inus confluentus adverselv affect Puget Sound Chinook Sahnon Threatened Designated Not likely to Yes Oncorhynchus tshawytscha adversely affect species or critical habitat A discussion of site-specific information relevant to the proposed restoration project site is presented below. Although there are no threatened and endangered species occurring within the project area, there are Chinook, steelhead, and bull trout in downstream larger rivers. In order to reduce downstream temporary increases in turbidity and potential related effects on these three species offish, all 'in-water' construction work will take place during the appropriate fish window (July 1 to September 30), which tends to be the driest time of the year. In addition, best management practices such as installation of a silt fence, placement of staging areas in flat areas above the ordinary high water line with gravel pads, minimizing the number of trips heavy equipment makes though the site, and the revegetetation of disturbed areas will reduce the generation of turbidity during connection of the new channel to the new culvert. The Corps expects the proposed action will have "no effect" on Puget Sound steelhead, Puget Sound Chinook critical habitat, and Puget Sound bull trout critical habitat because they are not present in the project area and downstream effects will be miniscule. In addition, the Upper Springbrook restoration project will likely contribute to improved conditions in larger downstream sections of stream where species like Chinook salmon, steelhead, and bull trout do occur. By moving the stream away from the road, the downstream environments will no longer receive runoff from South 55th Street. By routing the stream Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 through a forested wetland, this small tributary will remain cooler during the summer months which will potentially lead to decreases in temperatures downstream. 4.7 CULTURAL RESOURCES 4.7.1 No Action No disturbance to any possible cultural and historic resources will occur under this alternative. 4. 7 .2 Preferred Alternative Information describing the effects on cultural and historic resources of the Green/Duwamish River basin is presented in Section 4.18 of the FPEIS (USACE and King County DNR 2000). The preferred alternative will have little potential to affect historic properties up to three feet below the current ground surface. It is unlikely ground disturbance below three feet will impact and historic properties, but given the geological nature of the project area, a Corps archaeologist will monitor the excavation stage of construction for cultural materials. The Corps has obtained concurrence with a finding of"No historic properties affected" from the State Historic Preservation Officer (SHPO), pending the monitoring of the project by a professional archaeologist" on May 3, 2010 (Appendix H). 4.8 NATIVE AMERICAN CONCERNS 4.8.1 No Action There will be no change in Native American concerns for the site under this alternative. 4.8.2 Preferred Alternative Information describing the effects on cultural and historic resources, including those of Native American concern, of the Green/Duwamish River basin is presented in Section 4.18 of the FPEIS (USACE and King County DNR 2000). A synopsis of site-specific information relevant to the proposed restoration project site is presented below. The project will improve habitat available to salmon in Upper Springbrook Creek by improving the quality of rearing and foraging habitat available to this important resource for Native American Tribes in the area. Coordination with the Muckleshoot Indian Tribe is ongoing to ensure tribal concerns regarding usual and accustomed fisheries are incorporated into the site design. Construction timing of the project should avoid impacts to both out-migrating juvenile salmonids and adults moving upstream to spawn. Thus, construction will also avoid impacts to resources of importance to the Muckleshoot Indian Tribe. Additionally, the Corps consulted with the Department of Archaeology and Historic Preservation (DAHP) and has attempted to consult with the Muckleshoot Tribe to determine potential effects of the proposed project on cultural and religious sites of importance to the Muckleshoot people. In addition, previously research has included a search of the DAHP Electronic Historic Sites Inventory Database and archival research. The Corps has not received a response from the Muckleshoot concerning this project. The Corps Archaeologist initiated formal consultation with the Muckleshoot Tribe via e-mail on 29 April 2010. The e-mail respectfully requested comment by 7 May 2010 concerning this project by explaining that this project was under a tight deadline due to its use of stimulus funds. A copy of the report and an official consultation letter Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 (Appendix H) were attached to this e-mail sent to the Cultnral Resonrces Manager and the Tribal Archaeologist of the Muckleshoot Tribe. In addition, phone calls and subsequent voice mails were placed to the Muckleshoot cultnral representatives above on 29 April 20 IO and 4 May 2010. There was no response to any of these communications. Finally, a follow up round of communications involving e-mails, phone calls with voicemails and a letter were all conducted on 6 May 20 IO requesting comment at their earliest convenience. These requests included the notification that the State Historic Preservation Office (SHPO) has concurred with the determination of "No Historic Properties Effected, pending monitoring by a professional archaeologist" on 3 May 2010. As of yet, representative(s) of the Muckleshoot Tribe have not responded to any of these attempts to coordinate. 4.9 LANDUSE 4.9.1 No Action There will be no changes to land use at the site under this alternative. 4.9.2 Preferred Alternative Information describing the environmental effects on land and shoreline use in the Green/Duwamish River basin is presented in Section 4.13 of the FPEIS (USACE and King County DNR 2000). A discussion of site-specific information relevant to the proposed restoration project site is presented below. Land use in the project vicinity will not change because of the creek relocation. The proposed project will not affect land use in areas adjacent to the project area, including nearby residential properties. However, construction vehicles may disrupt traffic for local residents. These impacts will be temporary and highly localized, and are therefore are not expected to be significant. 4.10 RECREATION 4.10.1 No Action Under this alternative, no changes in recreation will occur on site. 4.10.2 Preferred Alternative Information describing the environmental effects on recreation in the Green/Duwamish River basin is presented in Section 4.14 of the FPEIS (USACE and King County DNR 2000). A discussion of site-specific information relevant to the proposed restoration project site is presented below. Recreation in the project area is not expected to change significantly. There are no plans to put in any access trails; however the clearing of the invasive shrub vegetation may make access easier for those who will like to enjoy the creek. 4.11 AIR QUALITY AND NOISE 4.11.1 No Action No changes to air quality will occnr under this alternative. Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 4.11.2 Preferred Alternative Information describing the environmental effects on air quality and noise in the GreenlDuwamish River basin is presented in Sections 4.10 and 4.11, respectively, of the FPEIS (USACE and King County DNR 2000). A discussion of site-specific information relevant to the proposed restoration project site is presented below. Construction vehicles may temporarily increase air emissions and noise in the immediate project vicinity. Approximately 11 landowners surrounding the project area will experience impacts during construction. Noise associated with the use of heavy machinery may disturb local homeowners. However, these impacts will be temporary and highly localized, and will not result in significant impacts. For every gallon of diesel fuel burned, 22 pounds of COi are produced, and every gallon of gasoline produces 19.4 pounds of CO2 (USEPA, 2008). Based on two excavators and two haulers (500 horsepower each) operating, an estimated 76.66 tons of CO2 will be produced by construction equipment, using a roadway construction emissions spreadsheet model for non-road equipment (SMAQ:tvlD 2008). Also calculated for non-road construction equipment are carbon monoxide (CO), volatile organic carbons (VOCs), nitrogen oxides (NOx), particulate matter (PM), and sulfur oxides (SOx). In addition, loaded dump trucks that might get five miles per gallon of diesel will be required to haul off I 077 cubic yards of material and deliver 525 cubic yards of gravel. In addition to diesel use, there will be gasoline consumed in transporting Corps and construction personnel to the site. Table 5 outlines assumed emissions based on USEPA (2008) and SMAQ:tvlD (2008). Emissions from construction equipment will not exceed EPA's de minimis threshold or affect the implementation of Washington's Clean Air Act implementation plan. Tbe CO2 emissions listed below may seem insignificant compared to the thousands of metric tons emitted per year globally (Raupach et. al., 2007). Nevertheless, diesel fuel consumption by heavy machinery required for construction, material haul-off, and gasoline consumption for travel to the sites for all Corps projects, including this project, are a part of world-wide cumulative contributions to change in climate by way of increases in greenhouse gas emission. Table 5. Estimated emission (tons) of air pollutants and green house gases from operation of vehicles and construction equipment for Upper Springbrook Creek Channel Reali"nment and Rehabilitation ROG (ozone co nrecursorsl co, NOv PM SOx 2.llE- Non-road emissions* 0.11 0.07 76.66 0.79 0.03 06 Truck emissions * * 28.34 Personal vehicle emissions*** 0.58 *Construction equipment; based on spreadsheet model from SMAQMD (2008); assumes four 500-hp engines working 10 hrs per day, 15 days. •• Assumes 5 mpg diesel, 168 trips, 50 miles round trip for disposal, 25 miles round trip for gravel delivery. ••• Assumes 20 mpg gasoline, 4 round trips/day, 20 miles round trip. Final Envirorunental Assessment Upper Springbrook Creek Channel Realigoment and Rehabilitation May 2010 4.12 TRANSPORTATION 4.12.1 No Action No changes to transportation will occur under this alternative. 4.12.2 Preferred Alternative Information describing the environmental effects on traffic and transportation in the Green/Duwamish River basin is presented in Section 4.12 of the FPEIS (USACE and King County DNR 2000). A discussion of site-specific information relevant to the proposed restoration project site is presented below. Construction vehicles may temporarily increase the volume of traffic in the immediate project vicinity during excavation of the site. They may also disrupt traffic along South 55th Street and Talbot Road as vehicles access and depart the construction site. This may cause a slight increase in congestion during peak commuting hours. Local residents living on South 55th Street will be inconvenienced by an increase in machinery traffic during construction. Also, South 55th Street will need to closed to one lane in the area where the upstream culvert is located while the new culvert is being installed. However, these impacts will be temporary and highly localized, and are not expected to be significant. To minimize traffic impacts, a traffic control plan will be developed and implemented. 4.13 AESTHETICS 4.13.1 No Action Under this alternative no changes to aesthetics are expected to occur. 4.13.2 Preferred Alternative Information describing the environmental effects on visual quality and aesthetic resources of the Green/Duwamish River basin is presented in Section 4.15 of the FPEIS (USACE and King County DNR 2000). A discussion of site-specific information relevant to the proposed restoration project site is presented below. Removing Upper Springbrook Creek from the existing roadside ditch and relocating it into a more natural stream channel will greatly improve the visual and aesthetic appeal of the creek. A buffer of trees and shrubs will shield the creek from South 55th Street for the majority of the reach. Removal of invasive weeds and the planting of native vegetation will also increase the visual appeal of the site. During excavation and construction of the site, the aesthetic quality of the general area could be reduced due to the noise and air emissions generated by the construction equipment, which may disturb local homeowners. However, these impacts will be temporary and highly localized, and are not expected to result in significant impacts. 5. UNA VOIDABLE ADVERSE EFFECTS Unavoidable adverse effects of the proposed project include: Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 (1) Noise disturbance to wildlife and homeowners in the vicinity due to operating heavy machinery during excavation and construction of the restoration site. Most wildlife are anticipated to avoid the area while work is in progress. To reduce impacts, work will be conducted only during daylight hours in accordance with local noise ordinances. (2) Disruption of local traffic in the project vicinity during construction. Proper signage and flagmen will be utilized to address safety concerns and move traffic through the area as quickly as possible. (3) Mortality of forested wetland vegetation, including 10 larger alder trees and under-story shrubs within the project site. Planned plantings onsite will compensate for this impact. (4) Excavation of approximately 0.19 acres of existing forested wetland. The enhancement of the remaining wetlands by routing a creek channel through the area, removing invasive plant species, and planting native species will compensate for this loss by increasing the overall habitat function of the site. (5) Impacts to turbidity during the connection of the newly aligned stream to the upstream culvert and the downstream existing channel. (6) Impacts to the biota in the existing channel due to partial backfilling and diverting flow to the new channel. 6. CUMULATIVEIMPACTS Cumulative impacts result from the "individually minor but collectively significant actions taking place over a period of time" (40 CFR 1508.7). As such they include the impacts of this restoration project considered in conjunction with current and future projects constructed or planned within the lower Green/Duwamish River watershed. Multiple restoration projects are ongoing in the Green-Duwamish basin, both associated with the Corps and the Green-Duwamish ERP and associated with other efforts. Specifically, other ERP projects proposed for implementation in the near future include: Riverview Park Side Channel Construction, Big Spring Creek Restoration in Enumclaw, Meridian Creek Outlet and Wetland Restoration in Kent, and Mill Creek Wetland Restoration in Auburn. In addition, other ERP restoration projects have been completed in recent past (i.e. Site 1 Estuarine Restoration, Codiga Farms Side Channel Construction, Hamm Creek Realignment, and Meridian Valley Creek Realignment). Additional projects not associated with the ERP are planned or on-going in the Green-Duwamish watershed include invasive species removal, gravel nourishment, removal of fish barriers or culvert replacements, levee realignment, limiting livestock access to creeks, and public outreach efforts to educate the public about land use impacts. All of these efforts will result in long-term, cumulative benefits to the amount and functional value of restored habitat, improvements in the overall watershed condition, and will ultimately increase the ability of the watershed to support critical life history stages of native fish and wildlife populations. Other less beneficial activities in the watershed include ongoing levee and dam repairs and continued Final Environmental Assessment Upper Springbrook Creek Channel Realigrunent and Rehabilitation May 2010 development and ongoing land use practices all of which perpetuate the degraded condition of the Green River. Negative effects of the Upper Springbrook Creek Restoration project add to the cumulative negative effects by development and activities in the watershed. However, these negative effects are temporary and are associated only with the actual construction of the project, concentrated mainly in the channel, construction in the forested wetland, and when the new stream channel is hydraulically joined to the old channel before it exits under Highway 167. The combination of best management practices (BMPs) reduce the cumulative, short-term (i.e. construction related) impacts of these projects to an insignificant level. More significantly, the long-term beneficial effects generated by the project compensate for these short-term negative effects. Thus, the proposed restoration project will contribute to beneficial cumulative effects within the watershed from restoration activities and will help to incrementally offset adverse impacts on habitats from past, present, and future redevelopment projects along Upper Springbrook Creek. 7. COORDINATION Development and design of this project has been coordinated with involvement by the following agencies and entities: State of Washington Department of Fish and Wildlife U.S. Fish and Wildlife Service National Marine Fisheries Service Washington Department of Ecology Washington State Historic Preservation Office Muckleshoot Indian Tribe City of Renton, King County, Washington Corps of Engineers Sacramento District-agency technical review. A public comment period was held from 6, April 2010 to 6 May 2002. Comments received and the Corps responses to these comments can be found in Appendix I 8. ENVIRONMENTAL COMPLIANCE 8.1 National Environmental Policy Act This Environmental Assessment, dated May 2010, is intended to achieve NEPA compliance for the proposed project. As required by NEPA, this EA describes existing environmental conditions at the project site, the proposed action and alternatives, potential environmental impacts of the proposed project, and measures to minimize environmental impacts. The Corps invited submission of factual comment on the environmental impact of the proposed project. Comments were considered in determining whether it will be in the best public interest to proceed with the proposed project. The Corps considered all submissions received before the expiration date of the public notice that accompanied the draft environmental assessment. Based on the analysis in the EA and the comments received the Corps has determined that a Finding of No Significant Impact (FONSI) is appropriate. Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 8.2 Endangered Species Act of 1973 as amended (PL 93-205) In accordance with Section 7(a)(2) of the Endangered Species act of 1973, as amended, federally funded, constructed, permitted, or licensed projects must identify and evaluate any threatened and endangered species, and their critical habitat, that may be affected by an action proposed by that agency. Two separate Biological Assessments ( one for NMFS and one for USFWS) were prepared for the Green-Duwamish ERP in association with the (Final Programmatic Environmental Impact Statement) FPEIS which assessed potential effects to listed species from the proposed projects. The BAs determined that the proposed work was not likely to adversely affect endangered or threatened species or their critical habitats designated under the Act. Supplemental consultation for newly listed species and critical habitat has been determined to have "no effect", due to their absence at the project site and insignificant impacts to downstream reaches. Consultation with the service is, therefore, not required. 8.3 Clean Water Act Section 404 of the Clean Water Act authorized a permit program for the disposal of dredged or fill material into waters of the United States, and defined conditions which must be met by Federal projects before they may make such discharges. The Corps of Engineers retains primary responsibility for this permit program. The USA CE does not issue itself a permit under the program it administers, but rather demonstrates compliance with the substantive requirements of the Act through preparation of a 404(b )(I) evaluation. The Corps is preparing a 404(b)(l) evaluation to document findings regarding this project pursuant to Section 404 of the Act as well as Section 10 of the Rivers and Harbors Act of 1899. Preliminarily, the Corps believes that this project is analogous to the conditions of Nationwide Permit 27, Aquatic Habitat Restoration. This document can be found in Appendix F. Section 401 of the Act requires federal agencies to comply with EPA, state, or tribal water quality standards. EPA has delegated Section 40 I to the Washington Department of Ecology. This work requires a WQC from the Washington Department of Ecology for compliance with Section 401 of the Clean Water Act for work below the Ordinary High Water (OHW) line. On 28 April 20 I 0, the Corps received a 40 I certification under the conditions of a Nationwide Permit 27 from the Washington Department of Ecology (Appendix G). Section 402 of the Act requires a National Pollutant Discharge Elimination System (NPDES) permit and the associated implementing regulations for General Permit for Discharges from large and small construction activities for construction disturbance over one acre. This project will not have land disturbance of over one acre and therefore a NPDES permit need not be obtained. 8.4 Coastal Zone Management Act (16 USC 1456 et. seq.) The Coastal Zone Management Act of 1972 as amended (15 CFR 923) requires Federal agencies to carry out their activities in a manner, which is consistent to the maximum extent practicable with the enforceable policies of the approved Washington Coastal Zone Management Program. The proposed action will relocate a stream through an adjacent wetland, thus moving the shoreline. However, this project will not cause substantial adverse effects to shore resources or the environment. After review of the City of Renton Shoreline Master Plan, the Corps believes this proposal is consistent to the maximum extent practicable. On 28 April 2010, Coastal Zone ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~-37 Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 Consistency Determination concurrence was received from the Washington Department of Ecology (Appendix G). 8.5 National Historic Preservation Act (16 U.S.C. 470) The National Historic Preservation Act (I 6 USC 4 70) requires that the effects of proposed federal undertakings on sites, buildings structures, or objects included or eligible for the National Register of Historic Places must be identified and evaluated. The Upper Springbrook Creek project is Federal undertaking of the type which might affect historic properties. As such it is subject to the Section 106 process. The Corps, in order to comply with Section 106 of the NHP A has initiated historic properties studies for the proposed project. The area of potential effects for the project was defined as the project area, access road, and staging areas. There are no recorded properties listed in, or eligible for listing in the National Register of Historic Places (NRHP) within the project area of potential effects (APE). 8.6 Fish and Wildlife Coordination Act (16 U.S.C. 661) The Fish and Wildlife Coordination Act (16 U.S.C. 661) requires that wildlife conservation receive equal consideration and be coordinated with other features of water resource development projects. The Corps conducted a prograrrunatic consultation with USFWS for the Green-Duwamish ERP. A Fish and Wildlife Coordination Act Report was received for the Green-Duwamish ERP in association with the FPEIS. 8. 7 Bald and Golden Eagle Protection Act (BGEPA) (16 U.S.C. 668-668d) The BGEPA prohibits the taking, possession or commerce of bald and golden eagles, except under certain circumstances. Amendments in 1972 added penalties for violations of the act or related regulations. No take of either bald or golden eagles is likely during project construction. There are no observed nests at the project site and no known nests within a half mile of the project site. Therefore, no adverse affect to eagles are anticipated. If a nest or juveniles are observed during construction, appropriate measures will be taken to ensure no harassment occurs. 8.8 Wild and Scenic Rivers Act (16 U.S.C. 1271-1287) No portions of the Green River or its tributaries have been designated as a Wild and Scenic River and this act is therefore not applicable to the proposed work. 8.9 Executive Order 12898, Environmental Justice Executive Order 12898 directs every federal agency to identify and address disproportionately high and adverse human health or environmental affects of agency programs and activities on minority and low-income populations. The project does not involve the siting of a facility that will discharge pollutants or contaminants, so no human health effects will occur. Therefore the proposed action is in compliance with this order. Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 8.10 Executive Order 11990, Protection of Wetlands, May 24, 1977 Although 0.27 acres of wetlands will be impacted due to the excavation of the new channel and the placement of three staging areas for access during construction (only 0.19 acres will be permanently impacted), the overall gain in habitat functions and value that will result from relocating the creek away from the road, meandering it through the adjacent wetland, placing gravel suitable for fish spawning and invertebrate colonization, and planting native riparian vegetation are expected to offset this loss. 8.11 Executive Order 11988, Floodplain Management, 24 May 1977 Executive Order 11988 requires federal agencies to avoid, to the extent possible, the long and short-term adverse impacts associated with the occupancy of the floodplain, and to avoid direct and indirect support of floodplain development where there is a practicable alternative. In accomplishing this objective, "each agency shall provide leadership and shall take action to reduce the risk of flood loss, to minimize the impact of floods on human safety, health, and welfare, and to restore and preserve the natural and beneficial values served by flood plains." Toe proposed action will not create a change that will affect occupancy of the floodplain. 9. CONCLUSION Based on this Environmental Assessment and on coordination with Federal agencies, Native American Tribes, and State agencies, the Upper Springbrook Creek Restoration project is not expected to result in significant adverse environmental impacts. Toe Upper Springbrook Creek Restoration project is not considered a major Federal action having a significant impact on the human environment. Therefore, the preparation of an environmental impact statement is not required. Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 Literature Cited Connell, Margaret A., James G. Hallett, and Stephen B. WeStreet 1993. Wildlife Use of Riparian Habitats: A Literature Review. TEW-WLl-001. DEA. 2001. Hydraulic Report -State Route 167 Culvert Replacement, Upper Springbrook Creek, MP 23.6, King County. Prepared for Washington State Department of Transportation, Northwest Region, Seattle, Washington. David Evans & Associates, Inc. September 2001. Fishing Works. 2009. Panther Lake Fishing in King County. Accessed online at: http://www.fishingworks.com/lakes/washington/king/renton/panther-lake/ Hatza. 1995. Final Report: Comprehensive fisheries assessment of the Mill Creek, Garrison Creek and Springbrook system. Consultant report prepared for the City of Kent, Environmental Engineering. Kent, Washington. 114. pp.+ Appendices. Kerwin, J. and T. S. Nelson, (Eds.). December 2000. "Habitat Limiting Factors and Reconnaissance Assessment Report, Green/Duwamish and Central Puget Sound Watersheds (WRIA 9 and Vashon Island)." Washington Conservation Commission and the King County Department of Natural Resources. King County. 2005. King County Surface Water Design Manual. King County, Washington. King County Department of Development and Environmental Services. 2009. Land Use Atlas. Accessed online at: http://www.kingcounty.gov/property/permits/gis/LandUseAtlas.aspx KCDNRP (King County Department of Natural Resources and Parks). 2002. King County bull trout program: 2001 bull trout surveys, freshwater and marine nearshore. Prepared by Taylor Associates, Inc., Seattle, Washington. National Marine Fisheries Service (NMFS). 2005. Endangered and threatened species; Designation of Critical Habitat for 12 Evolutionary Significant Units of West Coast Salmon and Steelhead in Washington, Oregon and Idaho. NMFS. 2007. Endangered and Threatened Species: Final Listing Determination for Puget Sound Steelhead; Final Rule. 72 FR 26722-26735. NMFS. 2009. Species of Concern Information Page: Coho Salmon. Accessed online at: http://www.nmfs.noaa.gov/pr/pdfs/species/cohosalmon_detailed.pdf Puget Sound Clean Air Agency. 2008. 2007 Air Quality Data Summary. Accessed online at: http://www. pscleanai r. orq/news/library/reports/2007 AQ DSFinal. pdf Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 Raupach, R.M., G. Marland, P. Ciais, C. Le Cuere, J. Canadell, G. Klepper, and C. Field. 2007. Global and regional drivers of accelerating CO, emissions. Proceedings of the National Academy of Sciences I 04(24): I 0288-10293. SMAQMD (Sacramento Metropolitan Air Quality Management District). 2008. CEQA tools. Accessed online at: http://www.airquality.org/ceqa/index.shtml. U.S. Army Corps of Engineers {USACE) and King County Department of Natural Resources (DNR). 2000. Programmatic NEPNSEPAEnvironmental Impact Statement and Green/Duwamish River Restoration Plan. Seattle, WA. USACE. 2008. Phase 1 Environmental Site Assessment to Support the Upper Springbrook Creek Restoration Project. Seattle, WA. USDA (United States Department of Agriculture). 2009. Web Soil Survey. Accessed online at: http://websoilsurvey.nrcs.usda.gov/app/HomePage.htm USEPA (U.S. Environmental Protection Agency). 2008. Emission Facts: Average Carbon Dioxide Emissions Resulting from Gasoline and Diesel Fuel. Accessed online at: http://www.epa.gov/OMS/climate/420f0500 l .htm USFWS (US Fish and Wildlife Service). 1999. Endangered and Threatened Wildlife and Plants; Determination of Threatened Status for Bull Trout in the Coterminous United States: Final Rule. 50 FR 589110-58933 Washington Department of Fish and Wildlife (WDFW). 1975. A Catalog of Washington Streams and Salmon Utilization, Volume 1 Puget Sound WDFW. 1999. Washington GAP Data Analysis. Accessed online at: http://www.wdfw.wa.gov/wlm/gap/vdm.htm WDFW. 2002. Washington State salmon and steelhead stock inventory, Olympia, Washington WDFW. 2003. Design of Road Culverts for Fish Passage. Washington Department of Fish and Wildlife WDFW. 2008. Priority Habitat and.Species List (PHS). Accessed online at: http://wdfw.wa.gov/hab/phsli Streethtm Washington Department of Ecology (WDOE). 2008a. Hazardous Sites LiStreet Online at: http://www.ecy.wa.gov/pu bs/080904 3a. pdf Washington Department of Ecology (WDOE). 2008b. Water Quality Assessment Tool for Washington. Accessed online at: http://apps.ecy.wa.gov/wqawa2008/viewer.htm WDOE. 2009. Air Quality webpage. Accessed online at: http://www.ecy.wa.gov/air.html Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 WDOT (Washington Department of Transportation). 2001. Hydraulic Report: State Route 167 Culvert Replacement, Upper Springbrook Creek. WDOT0000-0231 Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 Appendix A Project Plans Final Envirorunental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 ff.iif.il -~~ ,1 US Arrpy Corps of Engineers Seattle District 3 GREEN DUWAMISH RIVER ECOSYSTEM RESTORATION ' 1 UPPER SPRINGBROOK CREEK PROJECT RENTON, WASHINGTON ' '' PN 134779 ,. .-,..ANCHOR \/-QEA ::::::::;: 10,:,,SCO .. IWALUvtM\Jf I lfWIIG>IAM.WA"211] -,U..0111 FY 10 t O"""-" WA<<~ VICINITY MAP NI.II ti.I SCA!.£ ffl US hMy C.,,po o!Eogln,or• S.OtU, OlouCt i . I... 1f ~ ~I ~ GI ~ ! g e ~ ~ e ~ . -, ~ I UU> j,, 1• . . ! ~' t;~ ~ ~ !1 ! h ~ ~1 iS!'! ; ... '° . !I " ' " , -li ' ' ,. ,! .. !, !' ·! " ,, •' i' gi i i ! 8 Plolc oumbor: G-1 ! ! IFSHEETMEASURES~~~-~1!:3'l"ITIS (Sheol 1 ol.lO A IIEOUCED PRINT. REDUCE SCALE ACCOROINGL Y. I D PROJECT INFORMATIOJ: I 2 1 :S I 4 1 5 1 ' , PROJECT LOCATIO!\I: SPRINGBROOK CREEK ATS 55TH ST. GENERAL CONSTRUCTION NOTES· IEZII BfTWEEN TALBOT RD, SAND EAST VALLEY · us kmy c..,,, FREEWAY (STATE ROUTE 167), RENTON, WA 98055 L ~~~~!~~~":,,1 ~~ Nc~:rEg;~;~~gN~~~;~::ci°v~:~~~l~:~ri~~AD~:~~NS ~~.91:::: AND WASHINGTON STATE DEPARTMEt.T CJF TRANSPORTATION IWSOOT) STANDARD ABBREVIATIONS COmRACTING AGENCY: U.S. ARMY CORPS OF ENGINEERS-SEATTLE DISTRICT DETAILS I CURRENT EDITION!, "5TANOAROSPEWICATION> FOR ROAD, BII.IDGf, AND A6!. TERM 4735 EAST MARGINAL WAY SOUTH MUNICIPAL CONSTRUCTION". ua """"'"'AnON SEATTLE, WA 98134 2. DETAIL.SARE INTENDED TO SHOW THE FINAL RESULT Of THE DESIGN, MINOR AMERICAN SODETY F<lRTEITIWGA~O MODIFICATIONS MAY BE 11.EUUIRW TO SUIT JOB SITE DIMENSIONS OR CONDITIONS AS'Tt.l W.TERIALI J POINT Of CONTACT: LYNN WETZLER, PROJECT MANAGER AND SUCH MODIFICATIONS SHALL BE INCLUDED A5 PART OF THE WORI(, CDf CONTROLLED DENSITI Fill i (2061764-3695 3. CONTRACTOR SHALL HEP JOB SITE AREA CLEAN AND HAZA/ID-FREE. CONTIIACTOII CSTC CRUSHEDSURFACIMGTOP mum SHALL DISPOSE OF ALL DIRT, DEBRIS, AND RUBBISH FOR DURATION OF THE WORIC. UPON COMPLETION OFWOR~ CONTRACTOR SHALL REMOVE ALL hllATERlAL AND 0~ lllUSHEDSURF~CING EIASE COURSE LOCAL SPONSOR: CITY OF RENTON EQUIPMENT NOT SPECIFlrn A5 RU,IIAlNING ON THE PROPERl't CFS cu,,cmr PER SECOND 1055 S. GRADY WAY 4, REl'RESENTATIONSOF"IBUE NORTH SHALL NOT BE USED TO IDENTIP/ OR ESTABLISH rnNc CONCRETE RENTON, WA 98057 THE BEARING OFTHUE NORTH AT THIS JOB SITE. ,,c,c_,~--eroe-~~'""'""--------< LOCAL SPONSOR CONTACT: ALLEN QUVNN,P.E., SURFACE WATER UTIUTY ENGINEER S. ~~E:.!'~EC~N~~i~~~ S~~~~lt.~~Tl(,SHOWN OR NOTED, THE OETAILSHALLBE CP CONTROL POINT{AI INSURl/fl') J 6. IN-STREAM WORr TO BE COMPlCTEO DURING SUhllhllER OF 2011 (1 /UL 11 • 30SEP Cl Cl.IS.CY ARD 1-CONSULTING ENGINEER: TRACY DRURY, P.E., PROJECT ENGINEER 11). SEE SPECIFICATIONS, PERMrfS, AND THESE Pl.ANS FDUURTHER DETAIL OOH DU\MfTER ATBREAITHl:IGHT J ANCHOR QEA LLC IN-STREAM WORK INUUDES AC'TIVITIESCONDUCTl'D IN EXISTING AND PROPOSED CHA DUANE HARTMAN &AW)Cu\HS 1605 CORNWALLAVENUE CHANNH.S 0.1. DUCTILE IRON BELLINGHAM WA 98225 OLO.. o, ..... rn~ (3601733•43 {1 x2l~ STANDARD CIVIL NOT!:S: t,'"0',--fo,;;;,.c.,.a,,~,,-------------j l. ALL SITE WORK SHALL BE A.S INDICAHD ON THE CONTRACT DOCUMENTS. fA. EACH I SHEET SEQUENCE SHEET NO. SHEET TITLE Z DO NOT f)(CAVAH OA OISTU/10 BEYOND THE PROJECT LIMITS UNLESS NOTED EIPS ElITRA IMP~D\/m Plowmn OTHERWISE. tLorELEY ELIYATIO/\I 1 G-1 COVER SHEET !. RUBBISH, DEBRIS, GARBAGE, AND OTHER REFUSE SHALL Bl: REMOVEO FRDM THE JOB srn ... ND DISPOSED OF LEGALLY, t'";;'----t,";,~;,'"""",,.---------j : 2 G-2 NOTES AND SPECIFICATIONS 4. NO TOPSOIL,. ORGAr.lC SPOILS, Fill, EXCAVATED MATERIAL, RIPR..,P, CONSTRUCTION fT. FOOTD! fEET MATERIAL, mu1PMENT, OR ANY OTHER SUCH ITEMS SHALL BE PlACEO, STOCKPILED, GAlY G"LV .. NIZ"EO 3 C-1 EXISTING CONDITIONS AND SURVEY CONTROL PLAN OR PARKED IN THE ROAOWAV SUCH THAT ITWOUill PREVENT A MINIMUM WIDTH HOPE HIGH OENSl!Y ffiLYETHYL<NE 4 C-2 PROJECT PLAN SITE MAP 'i ~~~!1~~~~~~:E~~;:;g(RIBEO ON THE CONTRACTOOCUMENT5, MUST HIM IIOTMIXASl'HALT . BE PLACED WITH A MAXIMUM LIFT DEPTH OF 12-INCHES AND COMPACTEQ A.S IE. JNYERT !LEV .. TION 5 C-3 PROJECT PLAN 1 DESCRIBED IN THE SPEOFICATIONSOR A.S INSTRUCTED BVCONTIIACTING OFFICER. IN. INCH Oil INCH(S 6 C-4 PROJECT PLAN 2 6. ~~:~~R~~~~~~·:::~~S~~~~ PROVIDE SAFETY TRAINING fOR THE WOR( :: ::E~:i:r.:~R!tR~:PE CO~f 7 C-5 PROJECT PLAN 3 7. THE AREAS OF11,E JOB srrE DISTURBED BVTHE WORK SHALL BE GRADED SMOOTH 1..1 WMPSUM TO THE PRE<ONSTRUCTION GRADE ANO PROTECTED ANO/OR REVEGETATEDAS MAJ: IM)'JMUM - 1-8 C-6 SITE ACCESS AND STAGING PLAN 8. ~ti~~~R~!~~~A,LL BE NEW ANO UNDAMAGED, UNLESS OTHHWISEAPPROVEO ~N. MINIMUM :i ;i:; rt: 9 C-7 CARE OF WATER PLAN BVTHE CONTRACTING OFFICER. THE SAME MANUFACTURER aF ~c~ IHM SHALL BE NAfl NO~THAM!R<CA"I °"'UM ~i ~ ~ 10 C-8.0 TYPICAL CHANNEL CROSS-SECTIONS ~~~~~~~~~~~;;,E WORK UNLESS OTHERWISEAPPRDVEO BV THE ~~s~ :~~~~:t•"IVE~TlullOATUM • ai ~ ,-.: 0 C. OM CENTE~ 11 C..S.1 TYPICAL CHANNEL CROSS-SECTIONS AND DETAILS UTIL!lY NOTES: o,; oveR~LO.o ELm•ic E 12 C.9,0 GRADING PLAN AND WOOD PLACEMENT CHANNEL STATIONS 0+00 TO 4+50 1· !~!i~~J"~~;~f~eE~~~~t~1g-;i:1~1~:~~T~~i~~~RAN~~N~iE~RF~ELD ;7L ~:;;:::.~~:G~:~:~INE ~ VERIFIED. THE CONTRACTOR SHALL lDCATI: AL.L E~ISTlNG UTILITIES PRIOR TO ORNER ti I I "II 13 C-9.1 GRADING PLAN AND WOOD PLACEMENT CHANNEL STATIONS 4+75 TO 9+60 CONSTRUCTION. THECONTRACTORSIIALLCONTACTTHE UTILIT'(LDCATIONREQUEST l'K P!CPEmc F; O~ CENTER (ONE·CA.ll CENTER) AT 911 FDR UTILITY lDCATIONS NOT LESS THAN TWO (2) PYC POL\'1/INYLClllDRIDE Z5 :!i 8 14 C-9.2 GRADING PROFILE BUSIIOIESS OAl'S BEFORE THE SCHEDULEO DATE FOR EA/ITHWORK OR TRENCHING QRTA QUARTER ~ !5 ~ TfiAT MAV IMPACT EXISTING UTILITIES. QT'I QllA~TITT j§: I: ~ ,l.1 15 C-9.3 SECTION VIEWS: STATIONS 9+60 TO 6+00 2 EXISTING TELECOMMUNICATIONS UTILITIES CONTACT INFORMATION. QWEST n.o.w !IGHT-Of-WA• 15 !l: ; . ,ll' COMMUNICATIONS INTERNATIONAL INC. BURIED LINE SERVICES. 1-800-566-3~, s SLOPE >-f 18 C-9A SECTION VIEWS: STATIONS 5+75 TO 2+00 CONTRACTOR I'S RESPONSIBLE FOR COORDINATION WITH UTIUTYOWNER5 , • ,w,, ! I REGARDING RELOCATION SERVICES. ..,. SANITAJIY S >! 17 C-9.5 SECTION VIEWS: STATIONS 1+75 TO 0-1-00 3. All AEIANDONEO UTlllTIESWHICH INTERFERE wrrH THE EXECUTION Of THE WOil~ SF SQ'-"'RE fOOTOR >.fl ~'===::: SHA1L BE VERIFIED BVTHE CONTRACTING OFFICER AND THE UTILITY FRANCHIS<: SD. SOUTH 18 C-10,0 CULVERT CONSTRUCTION PLAN AND PROFILE PRIOA TO DISTURBING THE UTILnlES. ONLY AFTU WRITTl:N ... PPROVALOF c,c,.c0-----1c.,c"c"c~c,c,,c,-------j • DISTURELANCI: OR MODIFICATION Of THE UTILITY FROM THE UTILITY FRANCHISE IS SSMH SAMIT ARY SEWER M.o.NIIOLI 1' iii 19 C-10.1 CULVERT CONSTRUCTION CROSS-SECTIONS RECEIVED BV THE CONTRACTING OfflCER MAY THE CONTRAC10R TAU ACTION. ~ [; f-4. SIZE, lOCATION, AND TYPE OF "1lY UNDERGROUND l/TILITIES OR IMPROVEMEIOITS ST"-STATION "'I j 20 C-10.2 CULVERT INLET PLAN AND CONNECTION DETAILS SHAll aE ACCURATiH NOTEO AND PLACED ON A5·BUILT DRAWINGS BV THE STRUCT. mucTVflE ; ~ i 21 C-10 3 CULVERT OUTLET PLAN AND DETAILS CONTAACTORAND ISSUED TO THE USACE ANO/OR ENGINEER AT COMPLETION OF !;'f SQUARHARD I! ' ' THE PROJECT. no TO Br 0£T£RM[NE0 ~ 22 C-10A CULVERT CHANNEL PLAN AND SECTIONS TVP moc.o.L ~ i: 23 C-11 SANITARY SEWER PLAN AND DETAILS SURVEY NOTES: USAU U.S.AIIMYCO~PSOHN~INEE!.5 ; i i1 g l. SURVEV PROVIDED BY: !i!,. < f 24 C-12.0 ROAD REPLACEMENT PLAN DUANE HARTMAN AND ASSOCIATES, INC. (DHAJOB No.07-121!1) WSDDT W"'5HINGTDN nAn: OEPAUMENT Of I' ' 1692B W000IN\IILLE·REDh110NO AOAO, B-107 llAl<SPORTATION !I, ;) l 25 C-12.1 ROAD REPLACEMENT SECTIONS WOODINVILLE,WJ\931172 wm WAHR5URfAUEl.l:\/ATION :,~ ~ 1425)483-535S <> ~ 26 C-13 FLOODPlAIN LOG PLACEMENT AND PLANTING DETAILS 2. SURVEYCONDUCTEDBE1WE[NJULY22ANOJULY29,2009AND I I ADOITIONALLV ON NO\IEM9ER 9, 2009. FOOT NOMINAL VERTICAL 27 C-14 TYPICAL DETAILS DATUM: NAVD88 28 L-1.0 PLANTING PLAN CHANNEL STATIONS 0+00 TO 4+20 3, ~.~t!zg~;:~~l~~~~~~~~l~~i6: 1 sTATE PLANE NORTH ZONE SASEO ON ,~:!:,, 29 L•1.1 PLANTING PLAN CHANNEL STATIONS 4+20 TO 9+60 KNOWN COORDINATES FR0hll0NS1TEOONTROL. G-2 30 L-2.0 PLANTING TABLE IF SHeer .,i:..su><Es LESSTHA!.1 22" ~ 34• rr 15 si,,..1 02,,1 ~o I I I I AREDUC.DPRIWT. REOUCESCALEACCOF«Jl,..,LV. ! ...,,, ... , ' ·--"'----"'~,--,-.... """""°""'""'O!Uf'T lm1!nll n-1,,1 [] ),11('111(]"! 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Ill g g z :!' ~ m m ril Cl ! 2 2 ! i ;ii ~ ~ 0 0 § g g ' ' -~ p t !t: :i: 0 C £ • ~ ~ ~ i l i ~ ~ ~ ~ m:rn:rnrn 1-1-·' 0 j! i :u g i ~ ~ ~ s i i I i I t , , . ' ' ' i ~ II ~ ; ~ i ~ ~ ~ ~ ' I • ;REEN ~UW-lll"ER ~ -~lUO !.1 ~ ---=,,,,_,;r ti1 I il PLAN~NG eL~ C><All~U ST>TIONS hZO ro , .. o C __:. • • -. ~ •~ -"" 1!141TI -- m -.,., --· •. ··•c,.-,.- ·-·~, ~ L;, I : J_,: .,, -i1, ' i: I \~,=:: -t )I -I:::\ I'~--:. -,1:,···; ·1~; -~ f·,·· -Iii( ~ j_\::1 .. ~ II ' !,i(' \!ii 1:,· .. L I:• ., ' I,: I I '· I I ... ,, Ii, ·.ii ,·,.: I .1;, l, I ,, I I I I·· I ··1 I, \f 1 j ' . ,. ! U.!LJ.RMY OIQIEEII ~CT.sE,1,TIL.E -;'.~MI 11 MAT 10 -·--=-lPIP~ I' -· i-.~Rr I \l:ANCHO< ou= • 0 ' ' '. ' ' ' ' ' ' '' ' + + :"· -t' + ..... ·-1-- +. + .,,. i ' ' ' "l.lr_--r.,,. l] - ' ' ' ' ' ' ' ' ' ' ' '"ltit '·.; ' ' ' ·~··' '-1-~ 'c ·-~ -1-.... '/ ... , ' ' ' ' ' ' ' ' ,. ' ' ' ' ' ' ' ,, ' ' ' ' ·.,,. ... .,,. +, ., ' . J-'r \ + + .}CU) .... / . " .·" ""I ;-t-r;,\'+ + + ·,~f + -1-.,, + ·"., ... +,.. ' ' ' -+ .... -1-\. + +' + -1-·-:.,"' + ,,'11' + .,, + . -1-. ... -1-, ' ' + + . + ~ -1--t' + .+ -1--t -1--1-+ ·+ + -1-..\' ~\ .... +~ ,f-l- -~--'l'-1.....V-I--1-"'" ..... -+' -I" ..i-... _ + k \ .Ir k k ~--. ' +-+ ·:---'\:t .t ~/ ' ' ' -.. +. ,,, ' ' --l"'r ,,.--I"·..;: . ' ' ' ' ' ' .;.-...... ' ' 0 lj I'-. ~ I I [J_]_I -- N " ~, • j~ Appendix B CENWS-PM-PL-ER 29 October 2008 MEMORANDUM FOR RECORD SUBJECT: UPPER SPRINGBROOK CREEK RESTORATION PROJECT Wetland delineation and determination at Upper Springbrook Creek 09/05/2008 Site visit to locate wetlands within the boundaries of a proposed stream restoration Field notes taken by Kristin Kerns as directed by Andrea Cummins The proposed project is to realign and restore Upper Springbrook Creek located in the City of Renton, King County, Washington. The current stream runs parallel to South 55th Street and into a culvert under Highway 167. The restoration will include constructing a more natural, meandering creek aligmnent along 950 feet of South 55th Street and replanting the riparian zone with appropriate native vegetation. During the site visit the project footprint was determined and assessed for potential impacts to wetlands. Site Location: Upper Springbrook Creek is located in Renton, Washington, Section 31, Township 23 North, and Range 5 East. The creek currently runs through private property, under South 55th Street via a culvert, parallel to South 55th Street, and into a culvert under Highway 167. The project area was located using aerial photos and project design diagrams. Site Description: Springbrook Creek has a stream length of 12.0 miles, and approximately 19.1 miles of tributary streams and 3.8 miles of drainage ditches, it is the largest sub basin in the lower Green River Basin. Springbrook Creek sub basin drains an area of about 15,763 acres and enters the Green River (via the Black River) at approximately RM 11. From its confluence with Mill Creek upstream to the State Route 167 highway crossing, which includes the area of the proposed project, Upper Springbrook Creek more closely resembles a drainage ditch than a natural stream. Dominant vegetation is invasive species: reed canary grass (Phalaris arundinacea), blackberry (Rubus annenicus) and knotweed (Polygonum cuspidatum and Polygonum bohemicum) in particular. Access to the stream in the project reach was impossible without prior mechanical removal of blackberry and knotweed. On the north side of the creek native vegetation is more prevalent. Alder (A/nus rubra), cottonwood (Populus balsamifera), salnionberry (Rubus spectabilis), dogwood (Cornus sericea), skunk cabbage (Lysichiton americanus) and piggyback plant (Tolmeia menziesil) are present to varying extents along the 950ft length of the stream. Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 Methods: Access to the project area was via nine previously cleared access points, in this report identified as #1 at the eastern most end of the project through #9 at the project boundary with Highway 167. It was not possible to walk the length of the project along either side of the stream due to the dense cover of blackberry and knotweed. Vegetation and soil data was collected (as required) at each of these entry points approximately 50ft in from the road and assessed for wetland indicators. A shovel was used to excavate soil to a depth of 16-18 inches. Soil samples were examined for hydric properties and the presence or absence of hydrology. Vegetation cover was visually estimated for each strata within a 30ft radius of the sample site. Soil pits were not dug in areas of standing water as the presence of surface water during the dry season and predominance of hydrophytic vegetation was considered visual confirmation of a wetland. Results: Vegetation throughout the project site was dominated by hydrophytes. Standing water was present in the eastern most 250ft of the site, at access points # I and #2. At access point #3 and #4 surface water was no longer present. Soil pits were dug and soils were determined to be sandy- silt in texture and marginally hydric. At access point #5, the soil was sandy in texture and very marginally hydric, possibly indicating the location of the previous stream channel. In addition, sand bags were observed in the vicinity of the soil pit and may have contributed to the presence of sand in the area. At access point #6 surface water was present; no soil pit was necessary. At access point #7 and #8 surface water was not present but soils were hydric. At access point #9, at the edge of the project site near Highway 167, soils were wet although no surface water was present. Soils were not colored at this location due to the extremely disturbed condition from highway construction and maintenance. Unambiguous wetland indicators (including standing water) were present at both ends of the project site, at access points #1, #2, #6, #7, #8 and #9. The center area, access points #3, #4, and #5, while dominated by hydrophytic vegetation had more marginal soil indicators. This may be due to presence of sand dominated, faster draining soil in this area, possibly the result of a previous stream channel location as discussed above. However, the landscape position of the site and the dry season hydrology present during the site visit both indicate the central area of the site to be wetland. Therefore, the entire project site was concluded to be wetland. Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 Wetland name or number WETLAND RA TING FOR1'1: -WESTERN WASHINGTON Version 2 • Updated July 2006 ta increase accuracy and reproducibility among users Up<lated Oct 2008 v.ith the new WDFW definitions for priority habitats Name of wetland (if known): . ll9(Jf 1/ sl' ~ v1.1,J,y{ t:,()l~ Cvnate of site visit: -- Rated by Mr-e.a~omM>h~ / C~r'r;;~~~ Yes_No ->j.., Date oftraininog. __ _ , . -I - SEC: TWNSHP: RNGE: lsS!I/RinAppendixD? Yes_ No_ Map of wetland unit: Figure __ Estimated size __ _ SUMMARY OF RATING Category based on FUNCTIONS provided by wetland I II ill IV ------ Category I= Score >=70 Category II = Score 51-69 . Category III= Score 30-50 Category N = Score < 30 Score for Water Quality Functions Score for Hydrologic Functions Score for Habitat Functions TOTAL score for Functions Category based on SPECIAL CHARACTERISTICS of wetland I_ II_ Does not Apply_ I "8 10 fK"l Final Category (choose the "highest" category from above) CJ Estuarine Natural Herita e Wetland Bo Mature Forest Old Growth Forest Coastal La oon Interdunal None of the above Wetland Rating.Fonn-western Wasl,ington version 2 To be Used '\\1th Ecology Publication Q4.Q6.Q25 Freshwater Tidal Check if unit has multiple HGM classes resent August 2004 Wethmd name or number Does the wetland nnit being rated meet any of the criteria below? If you answer YES to any of the questions below you will need to protect the wetland according to the regulations regarding the special characteristics found in the wetland. For the purposes of this rating system, "documented" means the wetland is on the a ro riate state or federal database. · SP2. Has the wetland unit been documented as habitatfor any State listed Threatened or Endangered a11imal species? For the purposes of this rating system, "documented" means the wetland is on the appropriate state database. Note: Wetlands with State listed plant species are categorized as Category I Natural Herita e Wetlands (see . 19 of data form). ?' , SP3, Does the wetland unit contain individuals of Priority species listed by the (( ! WDFW for the state? (_/ SP4. Does the wetland unit have a local significance in addition to itsfimctions? For example, the wetland has been identified in the Shoreline Master Program, the Critical Areas Ordinance, or in a local management plan as having special significance. To complete the next part of the data sheet vou will need to detennine the Hydrogeomorphic Class of the wetland being rated. x x X The hydrogeomorphic classification groups wetlands into those that function m similar ways. This simplifies the questions needed to answer how well the wetland functions. The Hydrogeomorphic Class of a wetland can be determmed using the key below. Seep. 24 for more detailed instructions on classifying wetlands. Wetland Rating Form~ western Washington 2 version 2 Updated with new WDFW definitions Oct. 2008 August2004 Wetland name or number Classification of Wetland Units in Western Washington 1. ~~ water levels in the entire unit usually controlled by tides (i.e. except during floods)? ~goto 2 YES -the wetland class is Tidal Fringe If yes, is the salinity of the water during periods of aunual low flow below 0.5 ppt {parts per thousand)? YES -Freshwater Tidal Fringe NO -Saltwater Tidal Fringe (Estuarine) ff your wetland can be classified as a Freshwater Tidal Fringe use the forms for Rfrerine wetlands. If it is Saltwater Tidal Fringe it is rated as an Estuari11e wetland. Weilands that were called estuarine in the first and second editions of the rating system are called Salt Water Tidal Fringe in the Hydrogeomorphic Classification. Estuarine wetlands were categorized separately in the earlier editions, and this separation is being kept in this revision. To maintain consistency between editions, the tern, "Estuarine" wetland is kept. Please note, however, that the characteristics that define Category I and II estuarine wetlands have changed (seep. ). 2. The entire wetland unit is flat and precipitation is the only source (>90%) of water to it. ~dwater and surface water runoff are NOT sources o-f water to the unit. ('._'_2go to 3 YES -The wetland class is Flats If your wetland can be classified as a "Flats" wetland, use the fom1 for Depressional wetlands. 3. Does the entire wetland unit meet both of the following criteria? · _The vegetated part of the wetland is on the shores of a body of permanent open water (without any vegetation on the surface) at least 20 acres (8 ha) in size; _At least 30% of the open water area is deeper than 6.6 ft (2 m)? go to 4 YES-The wetland class is Lake---fringe (Lacustrine Fringe) 4. oes the entire wetland unit meet all of the following criteria? __ The wetland is on a slope (slope can be very gradua[), __ The water flows through the wetland in one direction (unidirectional) and usually comes from seeps. It may flow subsurface, as sheetflow, or in a swale without distinct banks. __ The water leaves the wetland without being impounded? NOTE: Surface water does no/pond in these type of wetlands except occasionally in very small and shallow depressions or behind hummocks (depressions are usually ~ <3ft diameter and less than 1 foot deep_ f ( CJo to 5 YES -The wetland class is Slope Wetland Rating Form-western Washington 3 version 2 Updated with new WDFW definitions Oct. 2008 August2004 Wetland name or number 5. Does tXntire wetland unit meet all of the following criteria? The unit is in a valley, or stream channel, where it gets inundated by overbank flooding from that stream or river )<. The overbank flooding occurs at least once every two years. NOTE: The riverine unit can contain depressions that are filled with water when the river is NO -go to 6 · S -e wetland class is Riverine not flooding.~ 6. Is the entire wetlan unit in a topographic depression in which water ponds, or is saturated to the surface, at some time during the year. This means that any outlet, if present, is higher than the interior of the wetland. NO -go to 7 YES -The wetland class is Depressional 7. ls the entire wetland unit located in a very flat area with no obvious depression and no overbank flooding. The unit does not pond surface water more than a few inches. The unit seems to be maintained by high groundwater in the area. The wetland may be ditched, but has no obvious natural outlet. N.0 -go to 8 YES -The wetland class is Depressfonal 8. Your wetland unit seems to be difficultto classify and probably contains several different HGM clases. For example, seeps at the base of a slope may grade into a riverine floodplain, or a small stream within a depressional wetland has a zone of flooding along its sides. GO BACK AND IDENTIFY WHICH OF THE HYDROLOGIC REGIMES DESCRIBED IN QUESTIONS 1-7 APPLY TO DIFFERENT AREAS IN THE UNIT (make a rough sketch to help you decide). Use tbe following table to identify the appropriate class to use for the rating system if you have several HGM classes present within your wetland. NOTE: Use this table only if the class that is recommended in the second column represents 10% or more of the total area of the wetland unit being rated. If the area of the class listed in column 2 is less than 10% of the unit; classify the wetland using the class that represents more than 90% of the total area. Slope + Riverine (" \ Riverin" ·· ...--' Slone + Denressional Denressional Slooe + Lake-fringe Lake-fringe Depressional + Riverine along stream within boundary Depressional + Lake-fringe Salt Water Tidal Fringe and any other class of freshwater wetland Depressional Denressional Treat as ESTUARINE under wetlands with special characteristics If you are unable still to determine which of the above criteria apply to your wetland, or if you have more than 2 HGM classes within a wetland boundary, classify the wetland as Depressional for the rating. 'Netland Rating Form -western Washington 4 version 2 Updated with new WDFW definitions OcL 2008 August 2004 Wetland name or number D D 1. Does the wetland unit have the potential to improve water quality? D D D 1.1 Characteristics of surface water flows out of the wetland: Unit is a depression with no surface water leaving it (no outlet) points= 3 Unit has an intennittently flowing, OR highly constricted permanently flowing outlet points~ 2 Unit has an unconstricted, or shghtly constricted, surface outlet (.permanently flowing) points:.: l Unit is a ''flat" depression {Q. 7 on key)) or in the Flats class, with permanent surface outflow and no obvious natural outlet and/or outlet is a man-made ditch points= I (lf ditch is noJ.pe1·manently flowing U'eatunit as "intermittently flawing") Provide hoto or drawin S 1.2 The soil 2 inches below the surface ( or duff layer) is clay or organic (use NRCS definitions) YES NO points= 4 oints = 0 (seep.38) Figure_ D 1.3 Characteristics of persistent vegetation (emergent, shrub, and/or forest Cowardin class) Figure_ D D D Wetland has persistent, ungrazed, vegetation>= 95% of area points= 5 Wetland has persistent, ungrazed, vegetation>= 1/2 of area points= 3 Wetland has persistent, ungrazed vegetation>= 1/10 of area points= I Wetland has persistent, ungrazed vegetation <1/10 of area points= 0 Ma of Cowardin ve etation classes Dl.4 Characteristics ofseasonal ponding or inundation. This is the area of the wetland unit that is ponded for at least 2 months, but dries out sometime during the yeo.r. Do not count the area_ that is permanently ponded. Estimate area as the average condition 5 out of 10 yrs. Area seasonally ponded is> Y, total area of wetland Area seasonally ponded is> V. total area of wetland Area seasonally ponded is < V. total area of wetland points =4 points= 2 points= 0 Figure_ of H dro eriods r----------------------~=======--~-----Total for D 1 Add the points in the boxes above ~-+-----------------------------------~-----D D 2. Does the wetland unit have the opportunitv to improve water quality? Answer YES if you know or believe there are pollutants in groundwater or surface water coming into the wetland that would otherwise reduce water quality in streams, lakes or groundwater down gradient from the wetland. Note which of the following conditions provide the sources of pollutants. A. unit may have pollutants ,·omingfrom several sources, but any sinifle source wOuld qualify as dppo1"tuni'ty. Grazing in the wetland or within 150 ft Untreated stormwater discharges to wetland Tilled fields or orchards within 150 ft of wetland A stream or culvert discharges into wetland that drains developed areas, residential areas, farmed fields, roads) or clear-cut logging (seep. 44) Residential, urban areas, golf courses are within 150 ft of wetland multiplier W_etland is fed by groundwater high in phosphorus or nitrogen Other _______________ ~ YES multi lier is 2 NO multi lier is 1 D TOTAL-Water Quality Functions Multiply the score from Dl by D2 Add score to table 011 • 1 Wetland Rating Form-western Washington 5 version 2 Updated with new WDFW definitions Oct. 2008 August2004 \Vetland name or number D D D D 3. Does the wetland unit have the potential to reduce flooding and erosion? D 3. I Characteristics of surface water flows out of the wetland unit Unit is a depression With no surface water leaving it (no outlet) points= 4 Unit has an intermittently flowing. OR highly constricted permanently flowing outlet points~ 2 Unit is a "flat" depression (Q. 7 on.key), or in the Flats class, with permanent surface outflow and no obvious natural outlet and/or outlet is a man-made ditch points= 1 (If ditch fs not permanently Jfmving treat. unit as "intermilfently flowing'') Unit has an unconsrricted, or sli htl constricted~ surface outlet ennanen.tl D 3 .2 Depth of storage during wet periods Estimate the height of ponding above the bottom oft/re outlet. For units with no outlet mea.surefrom the suiface ofpemia11ent water or deepest part (if diy). Marks of ponding are 3 ft or more above the surface or bottom of outlet points -7 The wetland is a "headwater" wetland~' points = 5 Marks of ponding between 2 ft to< 3 ft from surface or bottom of outlet points -5 Marks are at least 0.5 ft to < 2 fl from surface or bottom of outlet points = 3 Unit is flat (yes to Q. 2 or Q .. 7 on key) but has small depressions on the surface that trap water points = I Marks of ondin less than 0.5 ft points= 0 D 3.3 Contribution of wetland unit to storage in the watershed Estimate the ratio of the area of upstream basin contributing surface water to the wetland to the area of the wetland unit itself The area of the basin is less than 10 times the area of unit points= 5 The area of the basin is 10 to 100 times the area of the unit points= 3 The area of the basin is more than 100 times the area of the unit points = 0 Entire unit is in the FLA TS class points -5 ~==========~=~----------------~==-~~-----Add the points in the boxes above Total for D 3 D !--+--------------------------~-----D D 4. Does the wetland unit have the opportunity to reduce flooding and erosion? (seep. 49) D Answer YES if the unit is in a location in the watershed where the flood storage, or reductiori in water velocity, it proyides helps. protect downstream property a_nd aquatic resources from flooding or excessive and/or erosive flows. Answer NO if the water coming into the. wetland is controlled by a structure such as flood gate, tide gate, flap valve. reservoir etc. OR you estimate that more than 90% of the water in the wetland is frOm groundwater in areas where damaging groundwater flooding does not occur. Note which of the following indicators of opportunity apply, -Wetland is in a headwater ofa river or stream that has flooding problems -Wetland drains to a river or stream that has flooding problems -Wetland has no outlet and impounds surface runoff water that might otherwise flow into a river or stream that has flooding problems ~ Other_~-~~~~~~~~~-~~~ YES multi lier is 2 NO multi lier is 1 TOTAL -Hydrologic Functions Multiply the score from D 3 by D 4 Add score to table on p. I Wetland Rating Form-western Washington 6 version 2 Updated with new WDFW definitions Oct. 2008 August 2004 multiplier ·wetland name or number R R R R 1. Does the wetland unit have the potential to improve water quality? R 1.1 Area of surface depressions within the riverine wetland that can trap sediments during a flooding event: Depressions cover > 3/ 4 area of wetland points = 8 Depressions cover> 1/2 area of wetland points = 4 If depressions > Y, of area of unit draw polygons on aerial photo or map Depressions present. but cover < 1/2 area of wetland points ~ 2 No de ressions resent oints = 0 R 1.2 Characteristics of the vegetation in the unit (areas with >90% cover at person height): Trees or shrubs > 2/3 the area of the unit points = 8 Trees or shrubs> 1/3 area of the unit points= 6 Figure_ Figure_ points= 6 points= 3 points=O Q.. es CJ ~-~===========~=~~~~~~~~~~~~--------4-----R Add the points in the boxes above I j (::) I !---+-~~~~~~~~~~~~~~~~~~----.---- R R 2. Does the wetland unit have the opportunity to improve water quality? (see p.53) R Answer YES if you know or believe there are pollutants in groundwater or surface water coming into the wetland that would otherwise reduce water quality in streams, lakes or groundwater downgradient from the wetland'? Note which of the following conditions provide the sources of pollutants. A writ may have pollutants coming from several sources, but any single source would qualify as opportunity. X Grazing in the wetland or within 150ft ,t-J Untreated stormwater discharges to wetland -Tilled fields or orchards within 150 feet,ofwetland ~ A stream or culvert discharges into wetland that drains developed areas, V residential areas, farmed fields, roads, or clear~cut logging A Residential, urban areas, golf courses are within 15 0 ft of wetland i, The river or stream linked to the wetland has a contributing basin where human activities have raised levels of sediment, toxic compounds or nutrients in the river water above standards for water quality 0 er ________________ _ multiplier is 2 NO multiplier is 1 .,_,,:.!.i:A,.,Le..-Water Quality Functions Multiply the score from R 1 byR 2 Add score to table 011 • I Comments Wetland Rating Form-western Washington 7 version 2 Updated with new \VDFW definitions Oct. 2008 August 2004 multiplier 0 D- Wetland name or number R R R R R R 3. Does the wetland unit have the potential to reduce flooding and erosion? R 3.1 Characteristics of the over bank storage the unit provides: Figure __ Estimate the average width of the wetland unit perpendicular to the direc/ion oft/re flow and the width of the stream or river channel (distance between banks). Calculate the ratio: ( average width of unit)/( average width of stream between banks). If the ratio is more than 20 points -9 If the ratio is between 10 -20 points= 6 If the ratio is 5 -<10 points -4 If the ratio is 1 -<5 points = 2 If the ratio is< 1 points -1 0f' Aerial hoto or' ma showin -avera e widths I R 3.2 Characteristics of vegetation that slow down water.velocities during floods: Treat Figure __ large woody debris as ''forest or shrub". Choose the points appropriate for the best description. (polygons ne:ed to have >90% cover at person height NOT Cowardin classes): Forest or shrub for > l /3 area OR herbaceous plants > 2/3 area points = 7 Forest or shrub for> 1110 area OR herbaceous plants> 1/3 area points= 4 -:J· Vegetation does not meet above criteria points -o Aerial hoto or ma showin ol ons of differentve elation es Add the points in the boxes above I =J;-=1 R 4. Does the wetland unit have the opportunity to reduce flooding and erosion? (see p.57) Answer YES if the unit is in a location in the watershed where the flood storage, or reduction in water velocity, it provides helps protect downstream property and aquatic resources _from flooding or excessive and/or erosive flo\vs. Note which of the /Ollowi'ng conr/3}ions apply_ A There are human stmctures and activities downstream (roads, buildings, bridges, farms) that can be damaged.by flooding. There are natural resources downstream (e.g. salmon redds) that can be damaged by flooding Other ______________ _ (Amwer NO if/he major source of water to.the wetla11d is controlled by a reservoir or the wetland is Iida/fringe along the sides of a dike) YES multiplier is 2 NO multiplier is I Comments TOT AL -Hydrologic Functions Multiply the score from R 3 by R 4 Add score to table on p. 1 multiplier ~ ·wetland Rating Fcinn -western .Washington 8 version 2 Updated with new WDFW definitions Oct 2008 August2004 Wetland name or number L L L L 1. Does the wetland unit have the potential to improve water quality? L LI Average width of vegetation along the lakeshore (use polygons ofCowardin classes): Vegetation is more than 33ft (!Om) wide points= 6 Vegetation is more than 16 (5m) wide and <33ft points= 3 Vegetation is more than 6ft (2m) wide and <16 ft points= I Vegetation is less than 6 ft wide. points = 0 Ma of Cowardin classes with widths marked L 1.2 Characteristics of tl1e vegetation in the wetland: choose the appropriate description that results in the highest points, and do not include any open water in your estimate of coverage. The herbaCeous plants caii be either the dominant Jann or as mi understory in a sh111b or fore_st community. These are not Cowardin classes. Area of Cover is total cover in the unil, but it can be in patches. NOTE: Herbaceous does not include aquatic bed. Cover of herbaceous plants is >90% of the vegetated area points= 6 Cover of herbaceous plants is >213 oftl1e vegetated area points= 4 Cover of herbaceous plants is > 113 of the vegetated area points = 3 Othe_r vegetation that is not aquatic b~d or herbaceous covers > 213 unit points = 3 Other vegetation that is not aquatic bed in> 113 vegetated area points= 1 Aquatic bed vegetation and open water cover> 2/3 of the writ points= 0 · (seep..59) Figure __ Figure_ L Ma with ol ons of different ve elation es 1----------------"""'-"""'-'"""'"""""'~=~==~="'----1-----Add the points in the boxes above ~-+-----------------------------------~-----L L L 2. Does the wetland have the opportunity to improve water quality? Answer YES if you know or believe there are pollutants in the lake.water, or polluted surface water flowing through the unit to the lake. Note whid1 of the following conditions prQvide the sources of pollutants. A unit may have pollutants coming from several sou.rces, but any single source would qualify as opportunity, Wetland is along the shores of a lake or reservoir that does not meet water quality standards Grazing in the wetland or within 150ft Polluted water discharges to wetland along upland edge Tilled fields or orchards within 150 feet of wetland Residential or urban areas are within 150 ft of wetland Parks with grassy areas that are maintained, ballfields, golf courses (all within 150 ft. oflake shore) Power boats with gasoline or diesel engines use the lake Other _______________ _ YES multiplier is 2 NO multi lier is 1 TOTAL -Water Quality Functions Multiply the score from L1 by L2 Add score to table 011 • 1 Comments Werland Rating Form -western Washington 9 version 2 Updated "ith new WDFW definitions Oct. 2008 August2004 (seep.61) multiplier Wetland name or number L L L 3. Does the wetland unit have the potential to reduce shoreline erosion? L 3 Distance along shore and average width ofCowardin classes along the lakeshore (do not include aquatic bed): (choose the highest scoring description that matches conditions in the welland) > Y. of distance is shrubs or forest at least 33 ft (!Om) wide points= 6 > Y. of distance is shrubs or forest at least 6 ft. (2 m) wide points = 4 > Y. distance is shrubs or forest at least 33 ft(lOm) wide points -4 Vegetation is at least 6 ft (2m) wide (any type except aquatic bed) points= 2 Vegetation is less than 6 ft (2m) wide (any type except aquatic bed) points= 0 i\~~tl~~ jl?~ii~&1~\'.;, (seep. 62) Figure_ Aerial hoto or ma with Cowardin ve etafion classes ~------------'-'======c....c=-==="--'======'--~----- L Record the points from the box above ~-~--------------------------------~-----L L 4. Does the wetland unit have the opportunitv to reduce erosion? Are there features along the shore that will be impacted if the shoreline erodes? Note which of the following conditions apply. There are human structures and activities along the upland edge of the wetland (buildings,. fields) that can be damaged by erosion. There are undisturbed natural resources along the upland edge of the wetland ( e.g. mature forests other wetlands) than can be damaged by shoreline erosion (seep.63) Other multiplier YES multiplier is 2 NO multiplier is 1 L TOTAL -Hydrologic Functions Multiply the score from L 3 byL 4 Add score to table 011 p. 1 Comments Wetland Rating Fonn-western Washington IO August2004 version 2 Updated with new WDFW definitions Oct. 2008 '\,Vetland name or number s s s s s S 1.1 Characteristics of average slope of unit: Slope isl% orless (a 1% slope has a I foot vertical drop in elevation for every JOO ft horizontal distance) points= 3 Slope is l % -2% points = 2 Slcpe is 2% -5% points = I Slope is greater than 5% points= 0 S 1.2 The soil 2 inches below the surface ( or duff layer) is clay or organic (use NRCS definilions) YES = 3 oints NO = 0 oints S 1.3 Characteristics of the vegetation in the wetland that trap sediments and pollutants: Figure_ Choose the points appropriate for the description that best fits the vegetation in the wetland. Dense vegetation means you have trouble seeing the soil surface (>75% cover), and uncut means not grazed or mowed and plants are higher than 6 inches. Dense, uncut, herbaceous vegetation> 90% of the wetland area points= 6 Dense, uncut, herbaceous vegetation> 1/2 of area points= 3 Dense, woody, vegetation> V. of area points = 2 Dense, tmcut, herbaceous vegetation> 1/4 of area points= 1 Does not meet any of the criteria above for vegetation points= 0 Aerial hoto or ma with ve elation ol ons Total for S I Add the points in the boxes above ,-----, ~-~-----------------------------------~-----s S 2. Does the wetland unit have the opportunity to improve water quality? (see p.67) s Answer YES if you know or believe there are pollutants in groundwater or surface water coming into the wetland that would oth'erniise reduce water quality in streams, ·lakes or groundwater downgraclient from the wetland. Note which of the following conditions provide the sources of pollutants. A·unit may have po?futants coming from several sources, but any single source would qualify as opportunity. Grazing in the wetland or within 150ft Untreated stom1water discharges to wetland Tilled fields, logging, or orchards within 150 feet of wetland Residential, urban areas, or golf courses are within 150 ft upslope of wetland Other, ______________ _ YES multiplier is 2 NO multiplier is I TOTAL -Water Quality Functions Multiply the score from Sl by S2 Add score to table 011 • 1 Comments Wetland Rating Form-western Washington 11 version 2 Updated with new WDFW definitions Oct. 2008 August 2004 multiplier Wetland name or number s s S 3. Does the wetland unit have the potential to reduce flooding and stream erosion? S 3.1 Characteristics of vegetation that reduce the velocity of surface flows during storms. Choose the points appropriate for the description that best fit conditions in the weiland. (stems of plants should be thick enough (usually> 1/8in), or dense enough, to remain erect during surface flows) Dense, uncut, rigid vegetation Covers > 90% of the area of the wetland. Dense, uncut, rigid vegetation> 1/2 area of wetland Dense, uncut, rigid vegetation> 1/4 area More than 1/4 of area is grazed, mowed, tilled or vegetation is points= 6 points= 3 points= 1 not ri id o-ints = 0 S 3 .2 Characteristics of slope wetland that holds back small amounts of flood flows: The slope wetland has small surface depressions that can retain water over at least 10% of its area. YES points = 2 NO oints = 0 ~----------------------~=--==~~----~-----Add the points in the boxes above s 1--+--------------------------4----- S 4. Does the wetland have the opportunitv to reduce flooding and erosion? seep. 70) s s Is the wetland in a landscape position where the reduction in water velocity it provides helps protect downstream property and aquatic resources from flooding or excessive and/or erosive flows? Note which of the following conditions apply. -Wetland has surface runoff that drains to a river or stream that has flooding problems -Other _______________ _ (Answer NO if the major source of water is comrol/ed by a reservoir (e.g. wetland is a seep that is on the downstream side of a dam) YES multi lier is 2 Nb multiplier is I Comments TOTAL -Hydrologic Functions Multiply the score from S 3 by S 4 Add score to table on p. I Wetland Rating Form -western Washington 12 August2004 version 2 Updated with new WDFW definitions Oct. 2008 multiplier Wetland name or number H 1. Does the wetland unit have the potential to provide habitat for many species? H 1.1 Vegetation structure (seep. 71) Check the types of vegetation classes present (as defined by Cowardin)-Size threshold for each class is!, acre or more than 10% of the area ijunit is smaller than 2.5 acres. __ Aquatic bed Emergent plants X Scrub/shrub (areas where shrubs have >30% cover) )< Forested (areas where trees have >30% cover) I_f the unit has a forested class check if: ...2:S,__The forested class has 3 out of 5 strata (canopy, sub-canopy, shrubs, herbaceous, moss/ground-cover) that each cover 20% witlrin the torested polygon Add the number of vegetation structures that qualify. If you have: 4 structures· or more 3 structures 2 structures Map of Cowardln vegetation classes l structure H 1.2. Hydroperiods (seep. 73) points= 4 points= 2 points= 1 omts = 0 Check the types of water regimes (hydroperiods) present within the wetland. The water regime has to cover more than I 0% of the wetland or ~ acre to count. (see text for descriptions of hydroperiods) __ Permanently flooded or inundated 4 or more types present points= 3 points= 2 point= 1 points= 0 Seasonally flooded or inundated 3 types present X Occasionally flooded or inundated 2 types present ....2(Saturated only I type present ~ Permanently flowing stream or-river in, or adjacent to, the wetland __ Seasonally flowing stream in, or adjacent to, the wetland __ Lake-frillge wetla11d = 2 points __ Freshwater tidal wetla11d = 2 points Map of hydroperiods H l.3. Richness of Plant Species (seep. 75) Count the number of plant species in the wetland that cover at least 10 ft 2 • (differe11t patches of the same species can be combined to meet the size threshold) You do not have to name the species. Do ,wt include Eurasian Mi/foil, reed ca11a1ygrass, purple loosestr/(e, If you counted: > 19 species Lisi species below if you want to: 5 • 19 species < S species Canadian Thistle points= 2 points= 1 points= 0 Figure_ Figure_ \ Total forpage S- Wetland Rating Fonn-western Washington 13 August 2004 version 2 Updated with new WDFW definitions Oct. 2008 Wetland name or number H 1.4. Interspersion of habitats (seep. 76) Decide from the diagrams below whether interspersion between Cowardin vegetation classes ( described in H 1.1 }, or the classes and unvegetated areas (can include open water or mudflats) is high, medium, low, or none. ~ ~ None -0 points Low-1 point ~ High -3 points ·-.•. ·.·.-. ->./.:·-.····.·.· .. ·. • C, " ·-·· :-,:< ,_., .. - Moderate -2 points [riparian braided channels] NOTE: If you have four or more classes or three vegetation classes and open water the ratina is alwa s "hi h''. Use map of Cowardln vegetation classes H 1.5. Special Habitat Features: (seep. 77) Check the habitat features that are present in the we_tlahd. The number of checks is the number_ofpoints you put into the next column. )<-.. Large, downed, woody debris within the wetland (>4in. diameter and 6 ft long). Xstanding snags (diameter at the bottom> 4 inches) in the wetland p,._ Undercut banks are present for at least 6.6. ft (2m) ~d/or ove~hanging ~egetation extends at · least 3.3 ft (Im) over a stream (or ditch) m, or conuguous with the umt, for at least33 ft (!Om) __ Stable steep banks of fine material that might be used by beaver or muskrat for denning (>30degree slope) OR signs of recent beaver activity are present (cut shrubs or trees that have not yet turned grey/brown) __ At least ',4 acre of thin~stemined persistent vegetation or woody branches are present _in areas that are permanently or seasonally iuundated.(structuresfor egg-laying by amphibians) __ Invasive plants cover less than 25% of the wetland area in each stratum of plants igure_ 3 NOTE: The 20% stated in earlv printings of the /nanua/ on page 78 is an error. ~-------------------------------------...----H 1. TOTAL Score -potential for providing habitat I C\ I L.__ ____________ ~A~M=th~e~s~co~r~es'-"--·o~m:.:..:..H~l~.l~.~H~l~.2~,~H~l~-3~,~H~l~.4~,H:;.ccl.~5--i..l--L~J Comments Wetland Rating Fenn-western Washington 14 August 2004 version 2 Updated with new WDFW definitions Oct. 2008 Wetland name or number H 2. Does the weUand unit have the opportunity to provide habitat for many species? H 2.1 Buffers (seep. 80) Choose the desc11J)tiOn that best represents condition of buffer of wetland unit. The highest scoring criterion that applies to the wetland is to be used in the rating. See text for definition of ''1thdisturbed. " -I 00 m (330ft) of relatively undisturbed vegetated areas, rocky areas, or open water >95% of circumference. No structures are within the undisturbed part of buffer. (relatively undisturbed also means no-grazing, no landscaping, no daily human use) Points= 5 -100 m_ (330 ft) of relatively undisturbed vegetated areas, rocky areas, or open water > 50% circumference. Points= 4 -50 n1 (170ft) of relatively undisturbed vegetated areas, rocky areas, or open water >95% circumference. Points= 4 -100 m (330ft) ofrelatively undisturbed vegetated areas, rocky areas, or opm water> 25% circumference, . Points= 3 -50 m (170ft) of relatively undisturbed vegetated areas, rocky areas, or open water for> 50% circumference. Points= 3 If buffer does not meet any of the criteria above -No paved areas (except paved trails) or buildings within 25 m (80ft) of wetland> 95% circumference. Light to moderate grazing, or lawns are OK. Points= 2 -No paved areas or buildings within 50m of wetland for >50% circumference. Light to moderate grazing, or lawns are. OK. Points = 2 -Heavy grazing in buffer. Points = 1 -Vegetated buffers are <2m wide (6.6ft) for more than 95% of the circumference (e.g. tilled fields, paving,_ basalt bedrock extend fO edge of wetland Points = 0. L Buffer does not meet any of the criteria above. Points = 1 Aerial photo showinq buffers H 2.2 Corridors and Connections (seep. 81) H 2.2.1 Is the wetland part of a relatively undisturbed and unbroken vegetated corridor (either riparian or upland) that is at least 150 ft wide, has at least 30% cover of shrubs, forest or native Undisturbed prairiet that connects to Cs~_est other wetlands or undisturbed uplands that.are at least 250 acres in size? (dams iii riparian corridors, heavily used gravel roads,paved roads, are considered breaks in the corridor). YES= 4 points (go la H 2.3) NO= go to H 2.2.2 H 2.2.2 ls the wetland part of a relatively undisturbed and unbroken vegetated corridor ( either riparian or upland) that is at least son wide, has at least 30% cover of shrubs or forest, and conoects to estuaries, other wetlands or undisturbed uplands that are at least 25 acres in size? .OR a Lake-fringe wetland, if it does not have an undisturbed corridor as in the question above? YES= 2 points (go 10 H 2.3) NO= H 2.2.3 H 2.2.3 Is tl1e wetland: within 5 mi (8km) of a brackish or salt water estuary OR within 3 mi ofa large field or pasture (>40 acres) OR witlun l mi of a lake greater than 20 acres? YES = 1 ooint NO = 0 points . Figure_ 2 Total forpage-.22_ WetlandRatingfomi-westem Washington 15 August2004 version 2 Updated with new WDFW definitions Oct. 2008 . Wetland name. or number H 2.3 Near or adjacent to other priority habitats listed by WDFW (see new and complete descriptions of WDFW priority habitats, and the comities in which they can be found, ill the PHS report http://wd(iv. wa.govl/lab/ollslisl!,tm) Which of the following priority habitats are within 330ft (100m) of the wetland unit~ NOTE: the connections do not have to be relatively undisturbed. __ Aspen Stands: Pure or mixed stands of aspen greater than 0.4 ha (1 acre). __ Biodiversity Areas and Corridors: Areas of habitat that are relatively important to various species of native fish and.wildlife (full descriptions [n WDFWPHS repartp. 152). __ Herbaceous Balds: Variable size patches of grass andforbs on shallow soils over bedrock. __ Old-growth/Mature forests: (Old-growth west of Cascade crest) Stands of at least 2 tree species, forming a multi-layered canopy with occasional small openings; with at least 20 trees/ha (8 trees/acre)> 81 cm (32 in) dbh or> 200 years of age. (Mature forests) Stands with average diameters exceeding 53 cm (21 in) dbh; crown cover may be less that I 00%; crovm cover may be less that 100%;.decay, decadence, numbers of srtagst and quantity of large downed material is generally Jess than that found in old-growth; 80 -200 years old west of tl1e Cascade crest. __ Oregon white Oak: Woodlaods Stands of pure oak or oak/conifer associations where canopy coverage of the oak component is important (full descriptions in WDFW PHS 'Ir report p. 158). _/_'-Riparian: The area adjacent to aquatic systems with flowing water-that contai.ns elements of both aquatic and terrestrial ecosystems which mutually influence each other. __ Westside Prairies: Herbaceous, non-forested plant communities that can either take the form of a dry prairie or a wet prairie (full descriptions in WDFW PHS report p.161). X. Instream: The combination of physical, biological, and chemical processes and conditions r-that interact to provide functional life history requirements for instream fish and wildlife resources. __ N earshore: Relatively undisturbed nearshore habitats. These include Coastal Nearshore, Open Coast Nearshore, and Puget Sound Nearshore. (full descriptions of habitats and the definition of relatively undisturbed are in WDFW report: pp. 167,169 and glossary in Appendix A). __ Caves: A naturally occurring cavity, recess, void, or·system of intercoruiected passages under the earth in soils, rock, ice, or other geological formations and is large enough to contain a human. __ Cliffs: Greater than 7.6 m (25 ft) high and occurring below 5000 ft. __ Talus: Homogenous areas of rock rubble ranging in average size 0.15 -2.0 m (0.5 -6.5 ft), composed of basalt, andesite, and/or sedimentary rock, including riprap slides arid mine tailings. May be associated with cliffs. pnags and Logs: Trees are considered snags if they are dead or dying and exhibit sufficient decay characteristics to en:3ple cavity excavation/use by wildlife. ·Priority snags_ have a diameter at breast height of> 51 cm (20 in) in western Washington and are> 2 m (6.5 ft) in height Priority logs are> 30 cm (12 in) in diameter at the largest end, and> 6 m (20 ft) long. If wetland has 3 or more priority habitats= 4 points If wetland has 2 priority habitats= 3 points lf wetland has 1 priority habitat= 1 point No.habitats= 0 points Nate: All vegetated wetlands are by definition a priority lzabitat but are not included in this list. Nearbv wetlands are addressed in question H 2.4) Wetland Rating Form ....,.western Washington· 16 August 2004 version 2 Updated with new WDFW definitions Oct. 2008 t \Vetland name or number H 2.4 Wetland Landscape (choose the one description of the landscape around the wetland that best fits) (seep. 84) There are at least 3 other wetlands within Y, mile, and the connections between them are relatively undisturbed (light grazing between wetlands OK, as is lake shore with some boating, but connections should NOT be bisected by paved roads, fill, fields, or other development. points= 5 The wetland is Lake-fringe on a lake with little disturbance and there are 3 other lake-fringe .-c-'Yetlands within Y, mile points = 5 , (~'fh.~re are at least 3 other wetlands within Yz mile, BUT the connections between the~ are ' · -_ ,disturbed · points = 3 ~he wetland is Lake-fringe on a lake with disturbance and there are 3 other lake-fringe . wetland within V, mile _ poin ts.2_ 3 __ (~T'here is at least 1 wetland within Y, mile_ points.ss-2 "i ~---=---- There are no wetlands within Yi mile. points= 0 -----H 2. TOT AL Score -opportunity for providing habitat I 2 I Add the scores from H2.l,H2.2, H2.3, H2.4 I I TOTAL forH I frompage 14 =zr.-= Total Score for Habitat Functions -add the points for H I, H 2 and record the result on /ti P. I Wet] .and Rating Fonn -western Washington 17 August2004 version 2 Updated with new WDFW definitions Oct. 2008 Wetland name or number CATEGORIZATION BASED ON SPECIAL CHARACTERISTICS Please determine if the wetland meets the attributes described below a11d circle tire appropriate a11swers a11d Category . Wetland Type . ... . .· . . . . Category · Circle the Category when the . · Checkoj}'a1iy criteria that apply to the wetland.· annrol)riate i:riieriii.are met. . . . . . . SC 1.0 Estuarine wetlands (seep. 86) Does the wetland unit meet the following criteria for Estuarine wetlands? -The donrinant water regime is tidal, -Vegetated, and -With a salinity greater than 0.5 ppt. YES= Go to SC 1.1 NO SC L1 Is the wetland unit within a National Wildlife Refuge, National Park, National Estuary Reserve, Natural Area Preserve, State Park or Educational, Environmental, or Scientific Reserve designated under WAC 332-30-151? YES = Categorv I NO <'O to SC 1.2 SC 1.2 Is the wetland unit at least I acre in size and meets at least two of the following three conditions? YES = Category I NO = Category ll -The wetland is relatively undisturbed(has no diking, ditching, filling, cultivation, grazing, and has less than 10% cover of non-native plant species. lfthe non-native Spartina spp. are the only species that cover more than 10% of the wetland, then the wetland should be given a dual rating (I/II). The area of Spartina would be rated a Category II while the relatively undisturbed upper marsh with native species would be a Category I. Do not, however, exclude the area of Spartina in determining the size threshold of 1 acre. -At least '/, of the landward edge of the wetland has a I 00 ft buffer of shrub, forest, or un-grazed or un-mowed grassland. -The wetland has at least 2 of the following features: tidal channels, depressions witl1 open water, or contiguous freshwater wetlands. Wetland Rating Form-western Washington 18 version 2 Updated with new WDFW definitions Oct. 2008 August2004 . Cat. I Cat. I Cat. II Dual rating VII Wetland name or number SC 2.0 Natural Heritage Wetlands (seep. 87) Natural Heritage wetlands have been identified by the Washington Natural Heritage Program/DNR as either high quality undisturbed wetlands or wetlands tbat support state Threatened, Endangered, or Sensitive plant species. SC 2.1 Is the wetland unit being rated in a Sectiontrownship/Range that contains a Natural Heritage wetland? (this question is used to screen out most sites before you need to contact WNHP/DNR) S/T/R information from Appendix D _ or accessed from WNHP/DNR web site _ YES __ -contact WNHP/DNR (seep. 79) and go to SC 2.2 NO SC 2.2 Has DNR identified the wetland as a !ugh quality undisturbed wetland or as or as a site with state threatened or endangered plant species? YES= Category I NO not a Heritage Wetland . . .. . •. . ' . . . SC 3.0 Bogs (seep. 87) Does the wetland unit (or any part of the unit) meet both the criteria for soils and vegetation in bogs? Use the key below to identify if the wetland is a bog. If you answer yes you will still need to rate the wetland based 011 its fu11ctio11s. 1. Does the unit have organic soil horizons (i.e. layers of organic soil), either peats or mucks, that compose 16 inches or more of the first 32 inches of the soil profile? (See Appendix B for a field key to identify organic soils)? Yes - go to Q. 3 No -go to Q. 2 2. Does the unit have organic soils, either peats or mucks that are less than 16 inches deep over bedrock, or an impenneable hardpan such as clay or volcanic ash, or that are floating on a lake or pond? Yes -go to Q. 3 No -Is not a bog for purpose ofrating 3. Does the unit have more than 70% cover of mosses at ground level, AND other plants, if present, consist of the "bog" species listed in Table 3 as a significant component of the vegetation (more than 30% of the total shrub and herbaceous cover consists of species in Table 3)? Yes -Is a bog for purpose of rating No -go to Q. 4 NOTE: If you are uncei:tain about the extent of mosses in the understory you may substitute that criterion by measuring the pH of the water that seeps into a hole dug at least 16" deep. If the pH is less than 5.0 and the "bog" plant species in Table 3 are present, the wetland is a bog. 1. Is the unit forested(> 30% cover) with sitka spruce, subalpine fir, western red cedar, western hemlock, lodgepole pine, quaking aspen, Englemann's spruce, or western white pine, WITH any of the species ( or combination of species) on the bog species plant list in Table 3 as a significant component of the ground cover (> 30% coverage of the total shrub/herbaceous cover)? 2. YES= Category I No_ Is not a bog for purpose of rating Wetland Racing Form-western Washington I 9 August 2004 version 2 Updated with new WDFW definitions Oct. 2008 Cat. I . . Cat. I Wetland name or number .. . . SC 4.0 Forested Wetlands (seep. 90) Does the wetland unit have at least l acre of forest that meet one of these criteria for the Department offish and Wildlife's forests as priority habitats? If you answer yes you will still need to rate the wetland based on its functions. -Old-growth forests: (west of Cascade crest) Stands of at least two tree species, forming a multi-layered canopy with occasional small openings; with at least 8 trees/acre (20 trees/hectare) that are at least 200 years of age OR have a diameter at breast height (dbh) of 32 inches (81 cm) or more, NOTE: The criterion for dbh is based on measurements for upland forests. Two-hundred year old trees in wetlands will often have a smaller dbh because their growth rates are often slower. The DFW criterion is and "OR" so old-growth forests do not necessarily have to have trees of this diameter. -Mature forests: (west of the Cascade Crest) Stands where the largest trees are 80 -200 years old OR have average diameters (dbh) exceeding 21 inches (53cm); crown cover may be less that 100%; decay, decadence, numbers of snags, and quantity of large downed material is generally Jess than that found in old-growth. YES = Category I NO _not a forested wetland with special characteristics SC 5,0 Wetlands in Coastal Lagoons (seep. 91) Does the wetland meet all of the following criteria of a wetland in a coastal lagoon? -The wetland lies in a depression adjacent to marine waters that is wholly or partially separated from marine waters by sandbanks, gravel banks, shingle, or, less frequently, rocks -The lagoon in which the wetland is located contains surface water that is saline or brackish(> 0.5 ppt) during most of the year in at least a portion of the lagoon (needs to .be measured near the bottom) YES =Goto SC 5.1 NO_. _ not a wetland in a coastal lagoon SC 5.1 Does the wetland meets all of the following three conditions? -The wetland is relatively undisturbed (has no diking, ditching, filling, cultivation, grazing), and has less than 20% cover of invasive plant species (see list of invasive species on p. 74 ). -At least% of the landward edge of the wetland has a 100 ft buffer of shrub, forest, or un-grazed or un-mowed grassland. -The wetland is larger than 1/10 acre (4350 square feet) YES = Category I NO = Category II Wetland Rating Form-\v(sttm Washington 20 August 2004 version 2 Updated with new WDFW definitions Oct. 2008 . Cat. I Cat. 1 Cat. II Wetland name or number SC 6.0 Jnterdunal Wetlands (seep. 93) Is the wetland unit west of the 1889 line (also called the Western Boundary of Upland Ownership or WBUO)? YES -go to SC 6.1 NO_ not an interdunal wetland for rating If you answer yes you will still need to rate the wet/a11d based 011 its fu11ctio11s. In practical terms that means the following geographic areas: • Long Beach Peninsula-lands west of SR 103 • Grayland-Westport-lands west of SR 105 • Ocean Shores-Copalis-lands west of SR 115 and SR 109 SC 6.1 ls the wetland one acre or larger, or is it in a mosaic of wetlands that is once acre or larger? YES = Category II NO -go to SC 6.2 Cat. ll SC 6.2 Is the unit between 0.1 and l acre, or is it in a mosaic of wetlands that is between 0.1 and I acre? YES = Category III Cat. III 1--t~J~c-.. ~t'~· -~i~+~-,.~:'o~t-,.~~~e~Y~ ... ~,-~ .. ~.,,~.,, · • <.<&ti '·-'>'·•' 'A.,,,f.~~~t:W,.: ··.;-~?~~•,,, '•3,-''"c :;~s!ltlt~tli1 . .. . .. < If · ou".answere'i1'N O ford1U. Wetland Rating Fann-western Washington 21 version 2 Updated \\oith new WDF\V definitions Oct. 2008 August 2004 Appendix C Upper Springbrook Creek Channel Realignment and Rehabilitation Draft Restoration, Maintenance, and Monitoring Plan April, 2010 Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 1. Introduction The Corps of Engineers and the City of Renton are proposing to realign a portion of Springbrook Creek, which is currently located in a roadside ditch directly parallel to South 55th Street, and extends through a JOO-foot easement on an adjacent forested wetland. The proposed work involves: (I) Replacing the culvert that crosses South 55th Street with a design approved by Washington Department offish and Wildlife (WDFW) for fish passage, (2) Realigning the channel through the forested wetland that lies to the north of South 55th Street, and (3) Placing woody debris and spawning gravel in the new channel and planting native riparian vegetation to create complex habitat for aquatic biota. I.I Project Goals and Objectives The overall objective of the Green-Duwamish Ecosystem restoration project is to restore significant ecosystem function, structure, and dynamic processes that have been degraded within the river basin. To accomplish this objective, the following basin-wide restoration goals were identified: • Improve the physical nature of existing degraded habitat. • Improve existing ecosystem functions and values. This includes improving riverine processes where reasonable. • Address important factors limiting habitat productivity. In the lower and middle basins of the Green River conifer vegetation has been nearly eliminated and replaced with pavement and development, particularly in the lower basin. Vegetation that still exists is dominated by deciduous trees and shrubs, some of which are aggressive invasive species. This lack of vegetated cover and encroaching urban and sub-urban development has lead to degraded in-stream habitat without a functional riparian buffer in both the mainstem Green River and its tributaries. Current conditions are devoid of complexity or refuge due to channel straightening and lack oflarge wood recruitment providing minimal opportunities for salmonids to spawn and rear, as well as poor conditions for other aquatic species. In addition, stormwater in the basin enters the rivers and streams via the extensive amount of imperious surface in the basin thus leading to poor water quality and flashy hydrology. The objectives of the Upper Springbrook Creek Channel Realignment and Rehabilitation are to: • Increase channel diversity (large woody debris, riffle and pool habitat, and suitable substrate for fish spawning and rearing) • Improve the quality ofriparian habitat, thereby increasing habitat quality for aquatic biota, and particularly, spawning and rearing habitat for salmonids. • Improve water quality and hydrology by decreasing the amount of the stormwater run-off the creek receives directly from South 55th Street. 1.2 Location The project is located in the City of Renton adjacent to South 55th Street just west of highway 167, in township 23 north, range 5 east, section 31. The project area includes a 950 foot long section of stream that flows though a JOO-foot-wide easement between the South 55th Street culvert and Highway 167. The project area is bordered to the north by a forested wetland owned by Springbrook Apartment Investors, LLC, and to the south by South 55th Street, with a private ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~-47 Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 residence on the south side of the road. The area topography slopes northward consisting primarily forested wetland rated as Category II per Washington Department of Ecology's Wetlands Rating System. Along the southern boundary of the project area, where the stream channel resides, there is a dense overgrowth of invasive Japanese knotweed and Himalayan blackberry. Larger trees become more prevalent further from the road and the density of the invasive species decreases. 1.3 Functional Lift in Aquatic Habitat Habitat limiting factors for the Springbrook Creek watershed include (King County, 2000): • Degraded water quality • Fish passage barriers • Lack of functional riparian habitat • Prolific invasive vegetation, some of which can lead to fish passage barriers • Lack oflarge woody debris • Siltation In order to move the channel away from South 55th Street and design a more natural morphology, there will be unavoidable impacts to the Category II wetland to the north of the existing channel. Permanent impacts to this wetland will result from the excavation 0.19 acres of soil to construct the new channel. This new channel will be lined with a one-foot layer of gravel suitable for fish spawning, and is technically considered to be fill placement in a wetland. Temporary impacts will results from two staging areas (totaling 0.04 acres); one on the upstream end and one on the downstream end of the project site. Upon completion of construction, all gravel and rock will be removed and staging areas and will be replanted with native vegetation; long term impacts are expected to be non-existent. In addition, several construction sequencing and best management practices will be utilized to minimize disturbance to the wetland. Despite the minor and temporal impacts to the forested wetland, the project is expected to result in an net gain in aquatic habitat value and function based on the following: I) Moving the stream away from the road and its associated run-off will decrease the amount of pollutants directly entering the stream and the overall "flashiness" of flow, 2) Creating meanders and placing large woody debris will promote pool-riffle structure and in-stream microhabitat for aquatic life, as well as slow down water during higher flows, 3) The introduction of gravel substrate suitable for benthic invertebrate colonization and salmonid spawning, 4) Providing fish passage to higher value upstream habitat, 6) Removing invasive vegetation from the project site, and 7) Planting native vegetation along the stream, in areas of disturbance, and in the decommissioned channel. Also, topography of the wetland, which slopes to the north, and the presence of alluvial soils suggests that Upper Springbrook Creek (which flows due west in this reach) historically flowed through this wetland. For these reasons, and given the habitat limiting factors in the system, the minor wetland impacts are justified in order to improve the overall habitat quality and provide a net functional lift to this degraded section of Upper Springbrook Creek. Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 2. Maintenance and Protection The restored habitats are designed to be ultimately self-sustaining. However, to ensure success of the plantings and the eventual development of the targeted plant communities and habitats, certain maintenance and protection activities will be conducted. The City of Renton (as the local sponsor) will be responsible for the long-term maintenance of the site. Maintenance and protection activities will include: • Replacement of dead plants, including substitution of unsuccessful species to obtain targeted percent cover performance criteria for the site. Established trees and shrubs that die over time will not be removed unless they pose a direct threat to safety of people or property. • Spring and fall inventories and removal of invasive species for the first five years post-construction. Invasive species such as Himalayan and cut leaf blackberry, reed canary grass, purple loosestrife, English ivy, butterfly bush, Scot's broom, and Japanese knotweed will be diligently controlled using manual methods to the greatest extent possible. Other control methods, including limited spot application of approved herbicide, could be employed if necessary if manual removal is not effective. The City of Renton will be responsible for the removal of invasive vegetation for 5 years following the completion of construction • Weed control matting, protective tree collars, chemical browse-repellants, and/or other measures will be implemented, as necessary to limit competitive pressures or browse damage to plantings. • Irrigation of riparian plantings from the end of May through the end of October as warranted by regional weather or on-site soil conditions. The City of Renton will be responsible for irrigation of the riparian planting for 5 years post construction. • King County Sensitive Area signage will be placed along the outer perimeter of the site to identify the area a sensitive landscape feature and limit vegetation trampling/pedestrian traffic. 3. Monitoring 3.1 Pre-construction and Construction Monitoring Because the success rate ofrestoration efforts is increased through the coordination and communication between all parties before and during construction, monitoring by the project biologists from the Corps will take place during construction. A pre-construction meeting of the personnel responsible for the design and those responsible for implementation of the restoration site will take place prior to the onset of construction. The purpose of the meeting will be to review the intent of the restoration plan, establish a pathway of communication during construction, agree upon the construction sequence and address and resolve any questions. As this is a habitat restoration project, the biological elements are critical to the design and ultimate success of the project. Therefore, the project biologists from the Corps will play a significant role in all decisions regarding project construction. The project biologists will be present on-site during all stages of the restoration process, including but not limited to,(]) Excavation of the new channel, (2) Installation of the fish exclusion fencing and fish rescue (3) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~49 Final Environmental Assessment Upper Springbrook Creek Channel Realigrunent and Rehabilitation May 2010 Final grading and approval of materials such as logs, (4) Placement of habitat structures, (5) Inspection of the plant materials and recommendation for their final placement before planting, ( 6) Making adjustments in planting plans, as needed, in response to as-built field conditions, (7) Ensuring that construction activities are conducted per the approved plan, and (8) Resolving problems that arise during implementation, thus lessening problems that might occur later during the post-construction monitoring phase. The project biologists will also review the 'as-built' site conditions (including elevations, number and species of installed plants, and photo points) immediately following construction to create a baseline condition against which the future evolution of the site will be measured. 3.2 Post-Construction Monitoring As a restoration project, this site will be dynamic and will evolve in accordance with river flow and sediment accumulation following diversion of flow into the new channel. Thus, strict achievement of predetermined 'performance standards' will not necessarily predict the success or reveal the failure of the restoration effort. The monitoring and evaluation will be flexible and will focus on determining whether the overall goals and objectives of the restoration are being met, as measured by performance targets. We will also use 'monitoring metrics', which do not have specific performance targets associated with them, in order to document some of the more unpredictable aspects of the development and use of the site. Evaluation of the evolution of the restored habitats will be based on the establishment of the targeted habitats within the restoration site and on the ecologic functioning of those habitats. Most post-construction monitoring will be conducted in years 2 and 6 following construction. Monitoring and maintenance of plants will occur more often, details are included in subsequent sections. Data collection will be used to further the understanding of restoration in an urban setting, with the focus on the development of in-stream and riparian habitats and their use by fish and invertebrates. Data collected will be integrated into the larger volume offish-use data that has been gathered in the lower Duwamish River as part of the Green-Duwamish Ecosystem Restoration General Investigation. The Corps and the City of Renton will use the knowledge gained through this restoration project to adaptively manage the project site and to improve the design and implementation of future restoration efforts in the area. 3.2.1 Evaluation of Specific Objectives Objective 1: Increase channel diversity (large woody debris, riffle and pool habitat, and suitable substrate for fish spawning and rearing) Performance Target 1, Emergent plant survival and percent cover: Because the creek will likely make adjustments at the site, changes in the relative proportions of the site supporting emergent communities are expected to influence the number and distribution of plants on the site. Emergent plant survival will be assessed by counting the number of live plants, and subtracting that number from the plant quantities listed on the As-Built planting plan. Percent coverage will be measured within plots ofa standard 3-foot diameter using the Braun-Blanquet cover-abundance technique, or other similar methodology. Plant mortality in excess of the standards listed below will be replaced with the same species or a substitute species (depending Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 on the extent and cause of the mortality) in quantities appropriate to maintain the survival and percent cover standards desired for this project • 100% after one year (per one year guarantee on plant materials), • 80% after two years • 50% cover after three years, and 70% cover after five years. Monitoring Metric 1, Fish Presence and Abundance: There are no specific performance standards for this metric. Measuring usage of the site by fish will be done using electroshocking methods in a section of stream for a length of approximately 35 times the mean stream width. Electroshocking will begin at a riffle and end at a riffle to limit the number of fish that escape the sampling. All fish will be identified to species and measured. This method will be done in the spring before March 1 and July 15 as directed by the Washington Department of Fish and Wildlife. Monitoring Metric 2, Coho Salmon Spawning Surveys There are no specific performance standards for this metric. Methods are still to be determined. Surveys will be done in October. Monitoring Metric 3, Benthic Invertebrate Diversity and Abundance There are no specific performance standards for this metric. Benthic invertebrates will be sampled using Hess sampler methodology or equivalent. All benthic invertebrates will be identified to family and enumerated. Sampling will be done in July. Monitoring Metric 4, Frequency and Size of Pools and Riffles: There are no specific performance standards for this metric. Parameters such as width to depth ratio of pools and riffles, volume of pools, number of and length of pools and riffles, and distances between will be collected in the summer. Monitoring Metric 5, Channel Sinuosity: There are no specific performance standards for this metric. Sinuosity will be measured in the summer and late fall. Monitoring Metric 6, Substrate Size Distribution: There are no specific performance standards for this metric. Methods are still to be determined. Measurements will be taken in the summer and late fall. Monitoring Metric 7, Large Woody Debris (LWD) Frequency: There are no specific performance standards for this metric. Number of large woody debris structures will be estimated and distance between each structure will be measured. Information will be collected in the summer and the late fall. Monitoring Metric 8, Water Depth and Velocity: There are no specific performance standards for this metric. Water depth will be measured with a yard or meter stick, wetted width will be measured with a measuring tape, and flow will measured with a flow meter. Velocity will be calculated from this information. Information will Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 be collected in the summer during a low flow event, in the early fall during base flow, and the late fall during a high flow event. Objective 2: Improve the quality riparian vegetation therefore increasing habitat quality for aquatic biota, and particularly, spawning and rearing habitat for salmonids. Performance Target 1, Riparian Plant survival: Because the stream will likely make adjustments in the elevations of the site, changes in the relative proportions of the site supporting mudflat and marsh communities are expected and will influence the number, species, and distribution of plants on the site. Plant survival will be assessed by counting (and marking for replacement) all dead trees and shrubs and subtracting that number from the plant quantities listed on the As-Built planting plan. Plant mortality in excess of these standards will be replaced with the same species or a substitute species (depending on the extent and cause of the mortality) in quantities appropriate to maintain the survival and percent cover standards desired for this project. Planted and desirable volunteer trees and shrubs should be healthy and have a survival rate of: • 100% after one year (per one year guarantee on plant materials), • 80% after two years, and every year thereafter through the end of the five- year monitoring period. Performance Target 2, Percent Coverage of Riparian Plants: Percent coverage will be measured within plots of a standard 30-foot diameter using the Braun-Blanquet cover-abundance technique, or other similar methodology. The target percent cover will be applied to sample plots within areas anticipated to support the target plant communities based on As-Built drawings, but may ultimately be applied to other areas of the site which evolve into the target communities. The condition the project is trying to achieve is for the planted and desirable volunteer tree, shrub, and herbaceous species to provide a minimum of the targeted percent cover as follows, or for the plants to be healthy, unsuppressed by invasive species, and expanding at a rate acceptable to the project team. This provision is intended to accommodate slower than anticipated growth due to unanticipated site conditions or the need for implementation of contingency measures: Cover Type Riparian Forested Community (trees and shrubs) Years After Planting One year Three years Five years Target% Coverage 25% 35% 50% Performance Target 3, Percent Coverage of Non-Native, Invasive Plants Percent cover of invasive vegetation, including blackberry, knotweed, loosestrife, reed canary grass, Scot's broom, English ivy, and butterfly bush, will not exceed 10%. Methods for monitoring this metric are to be determined. Monitoring Metric 1, Percent Overhanging Cover and Shading: Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 There are no specific performance standards for this metric. Methods will likely include the use of a densiometer and visual estimates. Information will be collected in the summer. Monitoring Metric 2, Wildlife Habitat Functions: There are no specific performance standards for this metric. Data collected will be used to document use of restored habitats by wildlife and will be added to the data set of wildlife use of other restoration sites in the lower Duwamish River. Increases in wildlife habitat functions will be documented primarily by seasonal bird and mammal surveys conducted at the site at least three times per year, generally timed in the early spring, summer, and winter to document the greatest diversity of bird species using the restoration site. Incidental observations of mammals, reptiles, and amphibians made during any site visit will also be recorded. Objective 3: Improve water quality by decreasing the anwunt of the stormwater run-off the creek receives from South 55th Street Monitoring Metric 1: Monitor Physical Water Quality Parameters There are no specific performance standards for this metric. The following parameters will be measured: dissolved oxygen, pH, conductivity, temperature, and turbidity. Information will be collected in the summer during low flow, in the fall during base flow, and in the late fall during a high flow event. Monitoring Metric 2: Monitor Chemical Water Quality Parameters Neither the Corps nor the City of Renton has the capability to measure chemical water quality parameters. Discussions with Washington Department of Ecology are anticipated about the potential for monitoring of nutrients, metals, and other pollutants at this site. 4. Adaptive Management and Contingencies Potential scenarios that will require adaptive management of the site, along with conceptual approaches to correct problems, are presented below. Specific corrective actions will be determined based on site conditions and project history and will be determined collectively by the City of Renton and the Corps. Potential Scenario: Less than the targeted percent survival of planted vegetation species. Potential corrective actions: replanting to maintain targeted plant survival, substitution of failing species with different species more appropriate for site conditions. Potential Scenario: Percent coverage of plant not steadily increasing and/or does not meet targeted percent cover. Potential corrective actions: replanting, more aggressive invasive species control, substitution of species, fertilizer, soil amendment, irrigation, browse control measures, or other remedial actions to correct potential causes of poor growth. Final Enviromnental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 Potential Scenario: Blackberry, knotweed, loosestrife, reed canary grass, Scot's broom, English ivy, butterfly bush or other non-native, invasive plants constitute greater than 10% coverage of the restoration site. Potential corrective actions: manual removal, herbicide application, or mechanical grubbing of plants, off-site disposal required. 4.1 Initiating Procedures Contingency measures will be implemented if the monitoring program ( or any other documented observations by qualified personnel) indicates goals and objectives are not being met. The Corps and the City of Renton, in coordination with regulatory and funding agencies, will then assess monitoring metric parameters and initiate the implementation of corrective actions to address the identified issue. 4.2 Responsible Parties The contingency plan may require extension of the monitoring phase of the project, especially if major changes in the plan are required. As applicable, Corps project biologists and engineers, in consultation with agency personnel, will make adaptive management recommendations. The parties responsible for implementation of the restoration plan and any associated contingencies are as follows: Project Manager City of Renton: Project Manager Corps: Project Biologists Corps: Literature Cited AllenQuynn City of Renton Lynn Wetlzer U.S. Army, Corps of Engineers, Seattle District 206-764-3695 Chemine Jackels U.S. Army, Corps of Engineers, Seattle District 206-764-3646 King County. 2000. WRIA 9 Habitat Limiting Factors and Reconnaissance Assessment for Salmon Habitat: Green/Duwamish and Central Puget Sound Watersheds. Accessed online at: http://www.govlink.org/watersheds/9/reports/Recon.aspx Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 AppendixD Concurrence Letters from NMFS and USFWS Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 APR 23 'El! 12' 03 NMFS NORTH,EST P-EGION . P.2/7 UNITED B1'ATES DEPARTMENT CF CCIMMERCE Natlanal Oceanic and Aimospherlo Adml~istratl11n NATIONAL MARINE FISHERIES SEfl\/!C!i Colonel Ralph H. Graves District Engineer Corps ofEnginern, Seattle District Post Office Box 3 7551 Seattle, Washington 98124-37SS Attention: Palifck '1. Cagney NoMhwast Region 7600 Sand Polnc Way N.c., 61dg. 1 So•<t!G, WA 98115 Re: Section 7 Informal Consultafion on the U.S • .Army Corps-~:r Enginewi' Green Duwamish Ecosystem Restoration Program, King County, Washington (NMFS No. WS:S-00-423) and Essential Fish Habitat Consultl!tion. Dear Colonel Gra=: This conespondence is in response to your request ;for consultation under the Endangered Species Act (BSA). Additionally, this letter serves to mee1 the requircmeiits for consultation undtt the Magnuson-Stevens Fishery Conserv.ttion axid Mimagem.ent Act (Magnuson-Stevens Act). ·~• - Endangered Species Aet ~ The Nat\ona! Marine Fisheries Semce (NMFS) has reviewed !Ee August 31, 2000 request for concu,~cnce with your findings of"xnay affect, not likely to adversely affect (NLAA)" for the ··above referenced program, based on the Programmatic Biologlcal Assessment (PBA, June 2000), Final Feasibility Report (October 2000), and Supplemental Letter (March 27, 2001). Your findings in regard to the listing of Puget Sound cbinook salmoii .. ( Oncorhynahus tshawyt.saha) ns Threatened under the ESA. · This consultation with 1he United States Army Corps of Engineers (ACOE) is coruh1cted under section 7(a)(2) of the ESA, and its implementing regulations, 50 CTR Part 402. , .•. i;..":' ·,::::, The NMFS has evaluated the 50 projects in this ten-year program directed at ecosystem habitat restord.tion and enhan=ent, largely for salmonids and especially Chinook salmon, l!Ilr.l concurs with your findings of''may affect, not likely to adversely affe~1;,• to either the species or the designated critical habitat for most of the projects ·(See Table l). Based on the ACOB's Supplemental Letter of March 27, :<DOl to the PBA, NMFS agrees with the assignment of the projects into four groups: early action (Calendai· Year 2001), Phase l projec1s (Years 2002- 2003), Phase 2 (Years 2004-2009), and those that require an individual consultation or reinitfotion under this consultation, based on requiring more detailed construction pl!lns. Five projects during Phase l are considered Demonstration Projectswruch will provide info!lllution on how to better implement larger scale projects planneo for P]l_ase 2 which ultimaiely occur at =: ... -~ ~ .. P. 3"7 ,· -2- ------·---·-.----· ·· .. --. --·-. ------------·--·--···---------~ -·--- multiple sites or units. Table I Green Duwamish Ecosystem Restoration Program Projects Project No Projeot Name Phase ESA Status Marine Proi ects I Ellion Bay Nearshore 1 Concur Tjdallv-Im]umced Esm~rine F:coi~ 2 Site 1, Duwamish l Con~ur 3 Riverton Side Channel l Concur 4 Codiga Fanns ~lyAction Concur Frec-flowiru! Riverine Projects 5 Black Rive: Marsh 2 Concur · 6 Gilliam Creek 2 Concur 7 Lower Springbrook Creel<; I Concur 8 Upper Springbrook Creek l Concux 9 Mill Creek East 2 Concur .10 Garrison Creek 2 Concur 11 Mullen Slough, Prentice Nursery Reach 2 Concur 12 Mullen Slough Reach 2 ·Concu., 13 Mill Creek, Schuler Brothers Reach 2 Concur 14 Mill Creek, Merlino Reach 2 Concur 1S Mill Creek, Wetland 5 K. Reach 2 Concur 16 Mill Creek, Goedeb Reach '?, . Conciu: 17 Gre<:n Riv"1' Park 1 Concur 18 Horsehead Bend Side Channel 1 Concur 19 NE Aub\lrn Creek 1 Concur 20 Meridian Valley Creek 1 Concur 21 Lake Meridian-Outlet Relocation 1 Concur 22 Olson Creek · 1 Concur 23 Rivet$ide Estates Side Channel 2 Concm: 24 Mainstem Maintenance l Concur for Demo 1 25 Porte;r Levee 2 Concur 26 Kaech Levee Pond 2 Concur 27 Ray Creek T rib Conidor 2 Concur 28. Hamikami Levee Modification· 2 c~ucur 29 Turley Levee Setback 2 Concur 30 Loans Levee Setback l Conctlr 31 Burns Creek Restoration 1 Concur 32 Middle Green River Large Woody Debris 1 Concur for Demo 33 34 35 36 37 38 39 40 .3 •. Middle Green River Gravel Replacement 1 · Flaming Geyser Landslide 2 · .. Flaming Geyser Side Channel 2 Newaukum Creek 1 Big Spring Creek 2 . Brunner Slough 1 Upper Green R Side Channel Enhancement 2 Upper Green River Gravel Replacement 1 Concur for Demo Individual1 Concur Concur for Demo Concur Concur Individual Concur for Demo Above Howard Hansen Dam 41 Gale Creek l ConCLit' 42 Bdundary Creek 2 Concur' 43 Sweeney Creek E.ru:iy Action Concur' 44 Olsen Creek. 2 Conciir' 45 May'Creek 2 Concui:3 46 Maywood Creek 2 c,;nc,.u-> 47 Go!dC!eek 2 Concur 48 Sunday Creek Riparian Planting 1 Concur 49 NOTth East Creek 2 Concur 50 Volunteet Revegetation 1 Cone~ ' Concurrence as NLAA for one demonstration unit in each project. 2 Eith<:r reinitiate this consultation or Initiate a new consultation, based on further Project designs. . I .... , I ' Culvert replacement projects will use NMFS' Guidelines for Salmonid Passage at Stream Crossings, Final Dtaft, March 28, 2000 (Appended). Those restoration projects in which NMFS concurs provide an inc.ease in quantity of critical and essential fish ha.bilat thou~ the removal of upland fill and the ren1oving offish passage impediments and an increase in quality ofthe·critical and essential fish habitat because of the reasons provided in your Biological Assessment and Supplemental Letter: 1) the work will be . done during a time of the year when chinook salmon are not present; 2) most of the upland · construction will take place "in the dry" with final co.nnection to the aquatic environment during permissible periods, 3) the implementation employs a landscape ecological approach for the entire Wltl:ershed from the headwaters of the Green Ri vec through the Duwrunish estuary to marine habitats in Elliott Bay shallow subtidal substrates; 4) these projects will complement other ongoing Green-Duwamish River Basin restoration and mitigation effotts; and 5) the project will meet all of the Washington Department of Fish and Wildlife Hydraulic Project Approval conditions. · This concludes informal consultation on these actions in accordance with 50 CFR 402.14(b)(l). The ACOE must reinitiate this ESA consultation if:l) new information reveals effects of the action that may affect listed 5JleCies in a way not previously considered; 2) the action is modified r . ..;,, , -4- in a manner that causes an effect to the listed species that was not previously considered;. or 3) a · new species is listed, or critical habitat d~ignated, that may be affected by the identified action. Essential Fish Habitat Federal agencies are obligated, under Section 305 ofthe·Magnuson-S.tevens Fishery Conservation and Management Act (MSA) (16 USC 1855(b)) and its implementing regulations {50CFR600), to con511lt with NMFS -rega:cdmg actions that ue authorized, funded, or undertaken by that agency, that may adversely affect Essential Fish Habitat (EFH). The MSA (§3) defines EFH as "those waters and substrate necessary to fish for spawning, breeding, feeding, or giowth to maturity." Furthermore, NMFS is required to provide the Federal agency with conservation recommendations which minimize the adverse effects ofth~ project and conserve EFH. This consultation is based, in part, on information provided by the Federal agency and descriptions of EF.H fer Pacific coast groundfish, coastal pelagic species, and Pacific salmon contained in the Fishery Management Plans produced by the Pacific Fisheries Management Council. The proposed actions and action areas are described in the Biological Assessment. The action area covers four different types ofhabitats: marine, tidally-influenced estuarine, and riverine. The mruine habitats contain designated EFH for various life-history stages of 46 species of groundfish, 4 coastal pelagic species, and three species of Pacific salmon; the cstu,,.rine habitats contain de.ignated EFH for various life-history stages of 17 species of groundfish. four coastal pelagic species, and three species of Pacific sabnon; and the.riverine habitats include designated .EI'H for various life-history stages of three species of Pacific salmon (Table 2).. 1nfonnation submitted by the ACOE in the Programmatic Biolosical Assessment is sufficient for NMFS to eonclude that the proposed action may adversely i..-npact EFH in the short term by: . ' 1. Increased siltation during in-water construction operations; and ' . . . 2. Release of previously unknown.chemical contamination dming constructioll. EFH Conservation Recommendations:· The conservation measures that the ACOE included as part of the proposed action are adequate to minimize the long-teQll adverse impa,:;ts from this project to designated EFH fot the species in Table 2. It is NMFS' understanding that the ACOE ii;i.tends ta implement the proposed activity with these built-in conservation measures that minimize potential adverse effect to the maximum extent practicable. While NMFS is satisfied with the nineteen General Best Miinagement Practices (BMPs, in Section 2.5) in the PEA, short-tenn impacts shciuld.be minimized with tl1e following recommendations. 1. Where gravel/cobble material is to be used in gravel replacement projects, it will be sieved (screen) to remove fine-grained materials smaller than l/4"in diameter (BMP #15). It is assumed projects will require same level of maintenance over time; this should not include in-water dredging of sediments. 1 , ...,, f .50 2. Construction activities will cease if ch~cal contaminatlon found at any site exceeds the· State of Washington sediment standards or Model Toxics Control Act, where applicable (BMP #16), until the contamination is either removed or the project abandoned. Please note that tbe MSA (§305(b)(4)(B))requires the Federal ageru:y to provide a written response to NMFS' BFH: conservation reco=idations :withiil 30 days of its receipt of this letter, This concludes BFH consultation in accordance with the MSA and 50CFR600. The ACOE must reinitiate EFH consultation with NMFS if the proposed action is substantially revised ma manner that may adverseLy affect EFH, or ifnew info:rmatio11. becomes available that affects the basi$ for NMPS' EFH conservation recommendations (SO CFR 600.920(k)). This concludes BSA and EFH consultations. If you have qucstiol)S regarding either of these consultations, please co:tllaet Robert Clark at 20/5-526-4338. Sincerely, Donna Darm Acting Regional Administrator. APR 23 '01 12:07 NMFS NORTiiJ,,EST REGIUN -6· Table 2, Species of fishes with designated EFH in the proposed action lll'CaS (M '" Marine, E = Estuarine, R ~ Riverine). GroQodri,,h redstripo rocldlsh (M) Dovor sol• (M, E) Sooc!cs s. ""(1/"ll!.e/" Miuosiomw nacificuy spiny dogfish (M, B) rose!hom rockfish (M) English sole (M) Sowlu., acctnthia., S. l,ahiomacu/aru, pa,-•-·· ve/u/,.,J big skat• (M) rory rocldish CM} flatlielld solo (M. E) Ra/ct blnoculara S. rosaceus H1"noaJ,,.,oidtJ slassodon Ca!Jfomift skat~ (M, E) rougheyc rockfi.!h (M) ~·tralo sole (M. E) RJ:da. inornata S. a/eutitmlll EcoJ.Ua tordam" · Joogn= slcate (M) sborpchin rockfish (M) rex !ole (M) Rmarhina S. iacenlru.s =·•to..,nhalus zachbw ra.tfi.ih (M. E) splitnose ro,idish (M) rock sole (M. E) HwlroJa.,./S col/tel. S. dln/onroa · Lenldonlfllta bi/Inoa/a Pacific e<>d (M, E) strlptail rockfish (M) sand sole (M. B) Oadus maC1"ocs~•a1,,. . s. ,a,:/C()/a Pseitlchthvs m.JanostldUS bal:e (M, E) tiger rocldlsh (M) starry ftotmder (M) Mer/uceha oroduc,us S. ntm-o~inchlS l'lalichthu• ,te/J<l/JlS bleck rockfish (M) vonnilion rocl:fish (M) a.rrowtooth flounder (M, E) Seba,,1es me/anons S. m/niatu! ,f,theresliw JJomlas bocnceio (M, E) yelloweyo ,ockfish CM) S. oaui:lsn/>lls S.. ruhutimur brown roekfJSh (M, E) yollowtail rooklish CM) Coastal l'el•gic S. aw"tcu1arus S. flavtt!:u, Soecics cano,y rockluh {M) shortspin• thon,yhcad {M) anchovy (M, B) · 8. nim.u'""er Sebcutalobus aiascanu.1 En~aulls motdl:/% Cb!na rocldlsh (M) ca!Jazon (M, E) Pacific sardin, (M, E) S. nebulo.rus Scornaenlchi~J~ mtumorenus Sardtnoo, sa~a, copper rockfJSb (M, J:l) lingcod (M, E) Pocific macl:orc.l (M, E) s. caw/nus Oohlodon .Jonvan,, Scomb~ l=oniCU/1 darkblotoh rockfiah (M) i:olp greonling (M, E) market squid (M, £) S. cri:merl Hexa~ramm0$ d~ca2rammu1 Lo/I= ooa/ucens ;rooostrlped rciolcfish (M) sablo!!sh (M, £) l'aclfi< salmon S. elan~arus Anoalo60ma flmhria Sno<!es Pacif"ic 001:an perch (M) Pacific saoddab (M. El ohinook (M, E, R} S. alutu., Ctth,,,-/chthv., $l!tdidus Oiioor"' •olrus tsh-··r,cha quil\back rock!Ish (M, E} botter soto (M, E) echo (M. E, R} S. ma//~er Jsoo<etta lsol""ls 0. /d.r,,.tch redbandod rockfish (M) curlfin sol, (M, E) · Puget Sound ptnk (M, E, R) S. babcoclci Plewonichthu, decurrens 0. -rbv,cha United States Department of the Interior F1SHAND WILDLIFE SERVICE Western Washington Office 510 Desmond Drive SE, Suite l 02 Lacey, Washington 98503 MAR 2 7 2001 Phone: (360) 753-9440 Fax: (360) 753-9008 Colonel Ralph H. Graves District Engineer Seattle District, Corps of Engineers P.O. Box3755 Seattle, Washington 98124-3755 Attention: Mr. Pat Cagney (FWS Reference: I-3-0l-I-0906) Dear Colonel Graves: This letter responds to your August 31, 2000 transmittal letter and Programmatic Biological Assessment (PBA) for the Green/Duwamish Ecosystem Restoration Program which we received on September 5, 2000. We are able to provide partial concurrence. The PBA covers forty-nine restoration projects within the Green/Duwamish River Basin that the Corps of Engineers (Corps) is proposing for implementation over a ten year period. Fish and Wildlife Service (Service) and Corps staff have discussed on a number of occasions the need for more detailed project information to complete the Section 7 consultation. The Service proposed that the Corps meet annually with the Service, prior to the construction season, to review any refinements m project details that could have an impact on federally listed species, but especially the Coastal/Puget Sound bull trout. The Corps informed us in January 2001, that they were uncomfortable with the requirement for future reviews because of the uncertainties that could potentially affect project implementation. Instead, the Corps requested that the Service treat the PBA as a batch consultation. You further asked that we separate out any of the projects that we considered to be lacking in sufficient detail to complete the consultation, as well as projects for which we could not concur with the Corps' effect determination. For the purposes of this consultation, we are treating the forty-nine projects described in the PBA as a batch consultation. The Corps of Engineers has determined that the actions, as described in its PBA, are not likely to adversely affect the bald eagle (Haliaeetus leucocephalus), marbled murrelet (Brachyramphus mannoratus), northern spotted owl (Strix occidentalis caurina), gray wolf(Canis lupus), Canada lynx (Lynx canadensis) and Coastal/Puget Sound bull trout (Salvelinus confluentus). Based on the information provided in the PBA and the Corps' final feasibility report for the Green/Duwamish River Basin ecosystem restoration study, we concur with the Corps' determination of effects for the bald eagle, marbled murrelet, northern spotted ow~ gray wolf, and Canada lynx. With regard to the Coastal/Puget Sound bull trout, we concur with the Corps' effect determination for forty-three of the forty-nine projects described in the PBA and listed in the attachment to this letter. These projects are covered under this consultation for a period of ten years. 16)\ECCIEU\§\E~ \ru MAR ::l C 7.0 01 US.ACE REGULATORY BRANCH We do not concur with the Corps' "not likely to adversely effect'' determination for the bull trout for the following six projects: (l) mainstem maintenance (Auburn to Elliott Bay); (2) middle Green River large woody debris placement; (3) middle Green River gravel replacement; ( 4) Flaming Geyser landslide control; (5) Newaukum Creek restoration; and (6) upper Green River gravel replacement. We reco=end that the Corps consult individually on these projects. Although these six projects are expected to benefit bull trout in the long term, we believe they have the potential to adversely affect bull trout in the short term. These projects are larger and more complex than the others, involve significant in-water work, and have not been developed in enough detail at this time for us to conclude that the adverse impacts to bull trout would be insignificant. As project details become more refined, our concern for these projects and their potential impact to bull trout may lessen. In the absence of detailed project information, we need to be more cautious and therefore conclude that bull trout foraging could be adversely affected in the short term as a result of fine sediment releases during the modification of streambanks, the construction of engineered log jams, the addition of spawning gravels and the construction of other habitat improvements. Elevated levels of sediment can reduce the abundance of bull trout prey resources as well as make it more difficult for bull trout to locate their prey. This concludes informal consultation pursuant to 50 CFR402.13. This project should be re- analyzed if new information reveals effects of the action that may affect listed species or critical habitat in a manner or to an extent not considered in this consultation; if the action is subsequently modified in a manner that causes an effect to the listed species or critical habitat that was not considered in this consultation; and/ or, if a new species is listed or critical habitat is designated that may be affected by this project. If you have further questions about this letter or your responsibilities under the Act, please contact Gwill Ging at (360) 753-6041 or John Grettenberger at (360) 753-6044. Attachment A. The U.S. Fish and Wildlife Service concurs with Corps of Engineers' not likely to adversely affect determination for the following projects: Lower Green/Duwamish River Sites Elliott Bay Nearshore Site 1, Duwamish Riverton Side Channel Codiga Farms Middle Basin Restoration Sites Black River Marsh Gilliam Creek Lower Springbrook Creek Upper Springbrook Creek Mill Creek Ellllt Garrison Creek. Mullen Slough, Prentice Nursery Reach Mullen Slough Reach Mill Creek, Schuler Brothers Reach Mill Creek, Merlino Reach. Mill Creek, Wetland SK Reach. Mill Creek, Goedeke Reach Green River Park Horsehead Bend Side Channel. NE Auburn Creek Meridian Valley Creek Lake Meridian Outlet Relocation Olson Creek Riverside Estates Side Channel Porter Levee Setback Kaech Levee Pond Ray Creek Trib Corridor Hamikami Levee Modification Turley Levee Setback Loans Levee Setback Buras Creek Restoration Flaming Geysers Side Channel Big Spring Creek Brunner Slough Upper Green River Side Channel Enhancement Upper Bllllin Restoration .Sites: Gale Creek Boundary Creek Sweeney Creek Olson Creek May Creek Maywood Creek Gold Creek Sunday Creek Riparian Planting North Ellllt Creek Appendix E 401 Certification Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 STATE Of WASHINGTON DEPARTMENT OF ECOLOGY Northwest Regional Office• 3190 160th Avenue SE• Bellevue, Washington 98008-5452 • (42.5) 649·70DO April 28,2010 United States Army Corps of Engineers Attn: Chemine Jackels PO Box 3755 Seattle, WA 98124 RE: U.S. Army Corps of Engii_ieers Reference #PL-10-02 Upper Springbrook Creek Channel Realignment and Rehabilitation Project, Renton, King Couuty, Washington Dear Ms. Jackels: Ecology has determined that the above project meets the requirements for Washington State 401 Water Quality Certification and Coastal Zone Management Act Consistency lU!der NWP #27. Therefore, an individual 401 certification will not be reqmred for this project. Any changes to your project that would impact water quality should be submitted in writing to Ecology before work begins for additional review. 1b.is letter does not exempt you from other requirements of federal, state, and local agencies. Please contact me if you have any questions regarding this letter at ( 425) 649-7129 or e-mail rpad461 !alecy. wa. gov. Sincerely, (,~,..L , ~,-(]~Cr Rebekah R ~ett Federal Permit Manager Shorelands and Environmental Assistance Program RRP:cja e-cc: Patrick McGraner, Ecology Larry Fisher, Washington Department of Fish and Wildlife Appendix F Clean Water Act Section 404(b)(l) Evaluation Upper Springbrook Creek Channel Realignment and Rehabilitation King County, Washington Final Environmental Assessment Clean Water Act Rivers and Harbors Act Prepared by: U.S. Army Corps of Engineers Seattle District Environmental Resources Section March 2010 ~ t.:.t.!J . US Army Corps of Engineers® Seattle District Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 Introduction The purpose of this document is to record the U.S. Army Corps of Engineers (USACE) compliance evaluation of a planned stream realignment and rehabilitation on Upper Springbrook Creek in the City of Renton, WA, pursuant to the Clean Water Act (CWA), the Rivers and Harbors Act (RHA), and the General Regulatory Policies of USACE. Specifically, Section 404 of the CW A requires an evaluation of impacts for work involving discharge of fill material into the waters of the U.S., and evaluation guidance can be found in the CWA 404(b)(l) Guidelines [40 CFR §230.12(a)]. Section 10 of the Rivers and Harbors Act [33 USC §403] prohibits modification to or creation of an obstruction within a navigable water of the U.S. unless recommended by the Secretary of the Army and authorized by the Chief of Engineers. The General Regulatory Policies of the Corps of Engineers [33 CFR §320.4(a)] provide measures for evaluating permit applications for activities undertaken in navigable waters. The main body of this document summarizes the information presented in Attachment A and includes relevant information from the Environmental Assessment for the project that was collected pursuant to the National Environmental Policy Act (NEPA) of 1969 [42 USC §4321 et seq.]. Attachment A provides the specific USA CE analysis of compliance with the CWA 404(b)(l) and the General Regulatory Policy requirements. Project Background The US Army Corps of Engineers, Seattle District, in concert with the City of Renton, Washington, is proposing to realign and rehabilitate a section of Upper Springbrook Creek in Renton, WA. Work will be done beginning in July 2011. This section of stream currently flows through a roadside ditch overgrown with invasive weeds that parallels the north side of South 55th Street for approximately 900 feet before its flows underneath Highway 167. In this reach, the creek is located less than 10 feet from the road and the only vegetative cover consists of dense stands of Japanese knotweed and Himalayan blackberry. The proposed work involves: (1) Replacing the culvert that crosses South 55th Street with a design approved by WDFW for fish passage, (2) Realigning the channel through an adjacent forested wetland that lies north of South 55th Street, and (3) Placing woody debris in the new channel and planting native riparian vegetation to create complex habitat for aquatic biota. Project Need Coho salm.on (Oncorhynchus kisutch), as well as other aquatic fauna, utilize this stream for spawning, rearing, foraging, and as refuge habitat. However, during high flow events, the straight, wood devoid channel provides little refugia, allowing for the potential of juvenile fish to be flushed further downstream. In addition, in its current location the stream receives urban runoff from South 55th Street, exposing aquatic biota to pollutants. Project Purpose The purpose of the Upper Springbrook Creek realignment and rehabilitation is to increase channel diversity (large woody debris, riffle and pool habitat, and suitable substrate for spawning coho) and Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 plant higher quality habitat providing stream-side vegetation to increase habitat value and ecosystem functions for aquatic biota, and particularly, improve spawning and rearing habitat for salmonids. In addition, moving the stream away from the road will create a vegetated buffer that will absorb the stormwater run-off from South 55th Street Proposed Action and Alternatives Alternatives considered under NEPA must include the proposed action (preferred alternative), and the no-action alternative. Other reasonable alternatives that meet the project purpose and need must also be considered in detail. Three alternatives were considered for the purposes of this project: 1) The No Action Alternative 2) Channel Realignment with Bioengineered Features to contain Bank Overtopping, and 3) Channel Realignment with a Berm. The no action alternative was eliminated because it did not meet the project objectives and alternative 3, channel realignment with a berm, was eliminated because of the associated environmental effects and additional compensatory mitigation required by the Washington Department of Ecology that will arise from the additional placement of fill in a forested wetland. Potentially Adverse Effects (Individually or Cumulatively) on the Aquatic Environment a. Effects on Physical, Chemical, or Biological Characteristics of the Aquatic Ecosystem Short term impacts from temporary increases in turbidity may result from construction activities and general disturbance due to the presence and operation of large equipment. The largest impact will occur during the connection of the relocated channel with a new culvert. In addition, there will be a pulse of sedimentation following diversion of the stream into the restored streambed, resulting in short term turbidity increases as the streambed adjusts to the new flow. There will be impacts to approximately 0.27 acres of wetland (ofwhich 0.19 acres will have permanent impacts) which include ten larger Alders and understory shrubs, due to the alignment of the new channel. However, aquatic habitat quality for plants, aquatic invertebrates, resident and anadromous fish, and local wildlife is expected to improve significantly. Meandering the stream and the placement of large woody debris will provide pool-riffle structure and allow flows to slow down during heavy rain events. The pools will be used as refuge and foraging habitat for fish. Riffles will provide habitat for aquatic invertebrates and will be utilized for spawning by adult coho salmon. Diverting the stream away from the road will greatly decrease the amount surface water run-off pollutants in-stream organisms are exposed to and reduce peak flows. Streambed gravel will line the channel, providing spawning habitat and better substrate for the production of aquatic insects and other benthic and epibenthic organisms. Planting the stream banks with native vegetation will provide shading that functions as a thermal refuge during warm summer days as well as providing a source of organic input for the food chain and insect drop as a direct source of food. Final Environmental Assessment Upper Springbrook Creek Channel Realigrunent and Rehabilitation May 2010 In addition, replacing the culvert underneath South 55th Street will increase conveyance and reduce flooding upstream. Not only will micro-habitat quality improve, but there will likely be an overall decrease in flashiness of the stream and the adjacent forested wetland. b. Effects on Recreational, Aesthetic, Historical, and Economic Values Recreation in the project area is not expected to change significantly. There are no plans to put in any access trail; however, clearing of the invasive shrub vegetation may make access easier for those who will like to enjoy the creek. During excavation and construction of the site, the aesthetic quality of the general area could be reduced due to the noise and air emissions generated by the construction equipment, which may disturb local homeowners. However, these impacts will be temporary and highly localized, and are not expected to result in significant impacts. Impacts to economic value are expected to be insignificant. In accordance with the National Historic Preservation Act (16 USC 470), historic properties have been investigated, and concurrence was received from the Washington State Historic Preservation Office (SHPO) on May 3, 2010. c. Findings There will be no significant adverse impacts to aquatic ecosystem functions and values. It is expected that aquatic ecosystem functions and values will increase by relocating the stream away from the road, meandering it though a forested wetland, and planting the banks with native vegetation. All Appropriate and Practicable Measures to Minimize Potential Harm to the Aquatic Ecosystem a. Impact Avoidance Measures Three project alternatives were evaluated in order to select the best alternative for minimizing cost and impact to the environment. The proposed project action was selected because it will have the least negative impact on the environment and generate the greatest potential gains for habitat value and ecosystem functions. b. Impact Minimization Measures USACE will take all practicable steps during construction of the project to minimize impacts to aquatic, terrestrial and wetland resources during construction. Contingencies will be in place if any of the water quality protection measures fail to achieve their intended function. USACE will observe all construction windows to ensure that impacts to migratory fish will be avoided or minimized. The minimization measures will be as follows: • Best management practices (BMPs), such as storrnwater runoff prevention, will be used to ensure that no unnecessary damage to the environment occurs • To mitigate turbid flow in the new channel, a temporary shallow trench or pool will be excavated downstream of the confluence of the new and existing channels, where the turbid water will be pumped into the floodplain. Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 • A temporary fish exclusion fence will be installed upstream of the South 55th Street Culvert prior to the release of water into the new channel to reduce the likelihood of fish migrating into the new channel with inadequate flow depths present. • Flow from the existing creek will be slowly and sequentially transferred to the new channel in an effort to closely monitor water quality conditions, stability of the new channel, and to perform fish rescue and recovery within the existing creek. • In-water work will occur only during the WDFW established fish window (July I-September 30). • A Corps biologist will periodically check on construction progress to ensure BMPs are in place and environmental impacts are properly avoided and minimized • Permanent impacts to wetlands will be limited to the footprint of the new channel. Temporary impacts will be limited to staging and access areas; machine travel in these areas will be minimized to the extent possible; and these areas will be replanted with native vegetation following completion of construction. • Areas disturbed by construction of the channel that are not improved will be covered in coir fabric to aid in short-term stabilization. • Coir fabric will also be installed along the banks of the new channel below the imported channel sediment and extend upland as necessary. Long-term stabilization will be established by riparian planting. c. Compensatory Mitigation Measures Although the project will result in impacts to approximately 0.27 acres of wetland (of which 0.19 acres will be permanently Jost) to realign the channel, the gain in habitat value and ecosystem function from moving the stream away from the road, meandering it through a forested wetland, and planting native vegetation will exceed this loss. d. Findings USA CE has determined that all appropriate and practicable measures have been taken to minimize potential harm to the environment. Other Factors in the Public Interest a. Fish and Wildlife USACE has coordinated construction activities with local Native American Tribes and state and federal resource agencies to ensure that only minimal impacts to fish and wildlife resources will occur. In-water portions of the project will take place during the designated fish window, established by WDFW, to avoid impacts to fish. A Corps biologist will check for perched bald eagles before construction begins to avoid and minimize disturbance due to large machinery. Work may be delayed ifit appears that there will be a disturbance to eagles. USACE has submitted a Programmatic Biological Assessment for the Green Duwamish Ecosystem restoration to the U.S. Fish and Wildlife Service and National Marine Fisheries Service, and has received concurrence of "may affect, not likely to adversely affect" for federally listed species located in the project area. Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 b. Water Quality. USACE concluded that this project will not violate state water quality standards and received a 401 certification from the Washington Department of Ecology under a Nationwide Permit 27 on April 28, 2010. c. Historical and Cultural Resources In accordance with the National Historic Preservation Act (16 USC 470), historic properties have been investigated, and concurrence was received from the Washington State Historic Preservation Office (SHPO) on May 3, 2010. e. Environmental Beuefits. The project will result in an overall increase in habitat value and function for aquatic life by moving the stream away from the road, meandering the channel through a forested wetland, placing substrates suitable for benthic invertebrate colonization and salmonid spawning, planting the banks with native vegetation, and providing upstream fish passage through the culvert underneath South 55th Street 9. Conclusions. USACE finds that this project is within the public's interest, complies with the substantive elements of Section 404 of the Clean Water Act and the Rivers and Harbors Act, and meets the 401 certification and Coastal Zone Management Consistency criteria per Nationwide Permit 27: Aquatic Habitat Restoration, Establishment, and Enhancement Activities. Attachment A Clean Water Act 404(b)(l) Evaluation [40 CFR §230] Permit Application Evaluation [33 CFR §320.4] 404/b)(l) Evaluation (40 CFR §230] Potential Impacts on Physical and Chemical Characteristics [Subpart CJ: 1. Substrate [230.20] The placement of gravel suitable for benthic invertebrate colonization and salmonid spawning is expected to lead to an overall increase in habitat value. 2. Suspended particulates/turbidity [230.21] Overall, water quality in this section of Upper Springbrook Creek should improve as a result of the project. Stormwater from South 55th Street will no longer run off directly into the creek, and the buffering wetland and planted decommissioned channel will act to filter pollutants from the runoff before it enters the creek. Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 Temporary increases in turbidity may result from construction activities. The largest impact will occur during the connection of the relocated channel with a new culvert. In addition, there will be a pulse of sedimentation following diversion of the stream into the restored streambed, resulting in short term turbidity increases as the streambed adjusts to the new flow. Localized shifting of sediments will continue sporadically as the new stream heals and adjusts. Construction techniques, sequencing, and timing will minimize soil disturbance to the extent practical to reduce the generation of turbidity during connection of the new channel to the new culvert. Similarly, the design and implementation of the erosion-control and the Storm Water Pollution Prevention (SWPPP) plans will incorporate best management practices (BMPs) to further reduce the duration and magnitude of the temporary increases in turbidity. Turbidity monitoring during construction will ensure that these temporary increases are in compliance with State Water Quality Conditions. 3. Water [230.22] The project is not expected to add any nutrients to the water that could affect the clarity, color, odor, or aesthetic value of the water, or that could reduce the suitability of Upper Springbrook Creek for aquatic organisms or recreation. Coniferous large woody debris, which is resistant to breakdown ( and therefore has low biochemical oxygen demand), will be placed to enhance fish habitat. 4. Current patterns and water circulation [230.23] The hydraulic regime is expected to improve with the replacement of the culvert and the meandering of the new stream channel. Replacing the culvert underneath South 55th Street will increase conveyance and reduce flooding upstream. Meandering the stream will provide the opportunity for flow to slow down at bends. The placement of large wood and plantings will provide areas of slow water by the creation of pools and minimize bank overtopping. In addition, relocating this section of stream away from South 55th Street will greatly decrease the amount of surface water runoff entering this section of stream farther decreasing peak flow during heavy rain events. 5. Normal water fluctuations (230.24]. Overall flashiness during high and low flow events in Upper Springbrook Creek is expected to decrease by moving the stream away from South 55th Street, designing a meandered channel, and providing a vegetated buffer to absorb surface water runoff. 6. Salinity gradients [230.25] Not applicable, since Upper Springbrook Creek is freshwater. Potential Impacts on Biological Characteristics of the Aquatic Ecosystem [Subpart DJ: 1. Threatened and endangered species (230.30] USACE has submitted a Programmatic Biological Assessment for the Green Duwamish Ecosystem restoration in 2001 to the U.S. Fish and Wildlife Service and National Marine Fisheries Service, and has received concurrence of "may affect, not likely to adversely affect" for ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~63 Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 federally listed species at that time. Since then, Chinook salmon and bull tout critical habitat has been established and Puget Sound steelhead have been listed as threatened. However, none of these occur in the project area, therefore a determination of "no effect" has been made for bull trout and Chinook critical habitat, and steelhead at Upper Springbrook Creek. 2. Fish, crustaceans, mollusks and other aquatic organisms in the food web [230.31] There may be temporary impacts to aquatic organisms during construction and connection of the channel. However, aquatic habitat quality conditions are expected improve greatly following construction. Meandering the stream and the placement of large woody debris will provide pool- riffle structure. The pools will be used as refuge and foraging habitat for fish. Riffles will provide habitat for aquatic invertebrates and will be utilized for spawning by adult coho salmon. Diverting the stream away from the road will greatly decrease the amount surface water run-off pollutants organisms are exposed to. Stream bed gravel will line the channel, providing spawning habitat and better substrate for the production of aquatic insects and other benthic and epibenthic organisms. Planting the stream banks with native vegetation will provide shading that functions as a thermal refuge during warm summer days as well as providing a source of organic input for the food chain and insect drop as a direct source of food. 3. Other wildlife [230.32] Birds and other wildlife may be temporarily displaced during construction due to noise and presence of construction vehicles. Because these impacts will only occur during the period of construction, they are expected to be discountable and temporary. Planting native trees and shrubs along the stream bank will increase the extent and species diversity restoration site by creating additional opportunities for foraging, nesting, cover, and refuge for a wide variety of species. Potential Impacts on Special Aquatic Sites [Subpart E]: 1. Sanctuaries and refuges [230.40] Not applicable, since Upper Springbrook Creek is not designated by local, state or federal regulations to be managed principally for the preservation and use offish and wildlife resources. 2. Wetlands [230.41] A field inspection of the project area determined that the forested area adjacent to the site, in which the new channel will be routed through, is a wetland. The realignment of the channel through this area will result in impacts to approximately 0.27 acres of wetland, of which 0.19 acres will be permanently lost. However, the gain in habitat value and ecosystem function from moving the stream away from the road, meandering it through a forested wetland, planting native vegetation, and providing fish passage upstream are expected to exceed this loss. 3. Mud flats [230.42] Not applicable, there are no mudflats present in streams. 4. Vegetated shallows [230.43] Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 Not applicable, there are no vegetated shallows in Upper Springbrook Creek. 5. Corral reefs [230.44] Not applicable. 6. Riffle and pool complexes [230.45] Little pool-rifle complex exist in the current channel due to its straightened morphology. Placing gravel and large woody debris in the new channel along with meandering it through a forested area will create pool-riffle structures that are beneficial to aquatic biota. Potential Effects on Human Use Characteristics [Subpart F]: 1. Municipal and private water supplies [230.50] The project will not impact water supply. 2. Recreational and commercial fisheries [230.51] There are no known commercial fisheries at or near the project area. For recreational and tribal harvest, the project is expected to improve spawning and rearing habitat for coho salmon by provide spawning gravels, increasing pool-rifle structure, planting the banks with native vegetation, moving the stream away from the surface runoff generated from South 55th Street, and provide fish passage to higher quality habitat upstream. 3. Water-related recreation [230.53] Recreation in the project area is not expected to change significantly. In general access to the site is difficult due to the dead ending of South 55th Street at Highway 167, residential development that surrounds the site, and no plans to put in an access trail. However with the clearing of the invasive shrub vegetation may make access easier for those who would like to enjoy the creek. 4. Aesthetics [230.53] During construction there will be some minor disturbance from heavy equipment noise and exhaust. 5. Parks, national and historic monuments, national seashores, wilderness areas, research sites and similar preserves [230.54] No such structures or areas are designated in the project area. Evaluation and Testing [Subpart G]: 1. General evaluation of dredged or fill material [230.60] The only fill to be placed on the site will be a layer of 6-inch minus fish gravel within the new channel. All imported material will be free from contamination and obtained from a permitted facility. Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 2. Chemical, biological, and physical evaluation and testing [230.61] Imported spawning gravel will have large grain size and come from a source free from contamination. Actions to Minimize Adverse Effects [Subpart H]: 1. Actions concerning the location of the discharge [230. 70] USA CE is not selecting a disposal site, but rather is excavating a channel and disposing of the material at an upland site. 2. Actions concerning the material to be discharged [230.71] A 6 inch layer offish gravel will be placed within the new channel. Rock will be placed at the temporary staging areas, but will be removed following construction completion. Most of the material from the stream excavation will be hauled out using the new channel as an access road; however 100 cubic yards of this material will be placed along the floodplain log berm where the willow stakes will be placed to encourage growth. 3. Actions controlling the material after discharge [230.72] The only material to be added to the site will be spawning gravel. There will be a pulse of sedimentation following diversion of the stream into the restored stream bed, resulting in short term turbidity increases as the streambed adjusts to the new flow, and localized shifting of sediments will continue sporadically as the new stream heals and adjusts. 4. Actions affecting the method of dispersion [230.73] See above. 5. Actions related to technology [230.74] No specific advanced technologies will be used to construct this site. 6. Actions affecting plant and animal populations [230.75] USACE has coordinated construction activities with local Native American Tribes and state and Federal resource agencies to ensure that minimal impacts to fishery and wildlife resources will occur. In-water portions of the project will take place during the designated fish window to avoid impacts to fish. Providing spawning gravels, increasing pool-riffle structure, planting the banks with native vegetation, moving the stream away from the surface runoff generated from South 55th Street, and providing fish passage to higher quality habitat upstream is expected to lead in an increase in habitat value for aquatic biota. A Corps biologist will check for perched bald eagles before construction begins to avoid and minimize disturbance due to large machinery. Work will be delayed if it appears that there will be a disturbance to eagles. In addition, fish rescue will take place prior to the initial connection with the new channel. 7. Actions affecting human use [230.76] The construction of the stabilization structure is not expected to diminish water quality or any other aesthetically pleasing feature of the aquatic site. 8. Other actions [230. 77] Best management practices (such as dust suppression measures) will be used to ensure that no unnecessary damage to the environment occurs during construction. General Policies for Evaluating Permit Applications [33 CFR §320.4] 1. Public Interest Review [320.4(a)] USACE finds this stream realignment and rehabilitation action to be in compliance with the Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 404(b)(l) guidelines and not contrary to public interest. 2. Effects on wetlands (320.4(b)] See 404(b )( 1) evaluation above. Minimal impacts to wetlands are expected that will be offset by the overall gain in habitat value of this restoration project. 3. Fish and wildlife [320.4(c)] USA CE consulted extensively with state and federal resource agencies, tribes and other interested members of the public on this action. 4. Water quality [320.4(d)] USACE certifies that this project will not violate Water Quality Standards as set forth by the Clean Water Act and received a401 Water Quality Certification under the conditions of Nationwide Permit 27 from the Washington Department of Ecology on April 28, 2010. 5. Historic, cultural, scenic, and recreational values [320.4(e)] No permit application is necessary for these values, and in accordance with the National Historic Preservation Act ( 16 USC 4 70), historic properties have been investigated, and concurrence was received from the Washington State Historic Preservation Office (SHPO) on May 3, 2010. Additionally, affected tribes will be consulted as required under NHP A. 6. Effects on limits of the Territorial Sea [320.4(1)] Not applicable, since the project will not occur in coastal waters. 7. Consideration of property ownership [320.4(g)] The property is owned by Springbrook Apartments. An easement has been granted to construct the project. 8. Activities affecting coastal zones [320.4(h)] A coastal zone consistency determination was received from the Washington Department of Ecology on April 28, 2010 per the conditions of a Nationwide Permit 27. 9. Activities in marine sanctuaries [320.4(i)] Not applicable, since the area is not a marine sanctuary. 10. Other federal, state, or local requirements [320.4(j)] USACE has concurrence from the U.S. Fish and Wildlife Service and National Marine Fisheries Service on the findings of the Programmatic Biological Assessment for the Green Duwamish Ecosystem Restoration Project. USA CE received a 401 Water Quality Certification per the conditions ofa Nationwide Permit 27 from the Washington Department of Ecology on May 3, 2010. The local sponsor, the City of Renton, is pursuing a Hydraulic Approval Permit with the Washington Department of Fish and Wildlife. 11. Safety ofimpoundment structures [320.(k)] Not applicable, since an impoundment structure is not being built. 12. Water supply and conservation [320.4(m)] No impacts to water supply are anticipated; therefore no permit is needed concerning water supply. 13. Energy conservation and development [320.4(n)] Not applicable. 14. Navigation [320.4(0)] Not applicable. 15. Environmental benefits [320.4(p)] The project will result in an overall increase in habitat value and function by moving the stream away from the road, meandering the channel through a forested wetland, placing substrates Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 suitable for benthic invertebrate colonization and salmonid spawning, planting the banks with native vegetation, and providing upstream fish passage through the culvert underneath South 55th Street. 16. Economics [320.4( q)) No impacts to economics are anticipated. 17. Mitigation [320.4(r)J. Although the project will result in impacts to approximately 0.27 acres of wetland (of which 0.19 will be permanently lost) to excavate the new channel, the gain in habitat value and ecosystem function from moving the stream away from the road, meandering it through a forested wetland, placing spawning gravels and large woody debris, and planting native vegetation are expected to exceed this loss. Therefore, no mitigation is required. Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 Appendix G COASTAL ZONE MANAGEMENT ACT CONSISTANCY DETERMINATION Upper Springbrook Creek Channel Realignment and Rehabilitation March,2010 This restoration and rehabilitation of Springbrook Creek is an activity undertaken by a Federal agency. The following constitutes a federal consistency determination with the enforceable provisions of the Washington Coastal Zone Management Program. 1. Introduction: The proposed Federal action applicable to this consistency determination is the channel realignment and rehabilitation of a section of Upper Springbrook Creek, as described in the Environmental Assessment. This determination of consistency with the Washington Coastal Zone Management Act is based on review of applicable sections of the City of Renton Shoreline Master Program. The determination of consistency is further confirmed through analogy to the provisions of the regional conditions under Nationwide Permit (NWP) 27 pursuant to the Corps of Engineers' Clean Water Act Section 404 permitting program. The regional conditions under NWP 27 provide that the State of Washington has predetermined its concurrence that the channel realignment and rehabilitation project meeting NWP 27 parameters is consistent with the State's coastal management program as long as individual review under CWA Section 401 is not triggered. The consequent State predetermination of concurrence with a conclusion of consistency provides extrinsic validation for the Corps' analysis that follows. 2. State Of Washington Shoreline Management Program. Primary responsibility for implementation of the State of Washington Shoreline Management Act of 1971 has been assigned to local governments. The applicable local government office responsible for King County is the King County Department of Development and Environmental Services. 3. Description of the City of Renton Plan. According to Renton Municipal Code (RMC) 4-3-090, Upper Springbrook Creek is not classified by the City and State as Shorelines of the State, and therefore RMC 4-3-050, Critical Areas Regulation, apply to this project site. The following outlines pertinent sections of the City of Renton program. The Corps of Engineers consistency determination is indicated in bold italics. 4-3-050 CRITICAL AREAS REGULATIONS: L. STREAMS AND LAKES: 1. Applicability/Lands to Which These Regulations Apply: These stream and lake regulations apply to sites containing all or portions of Class 2 to 4 streams or lakes and/or their buffers as Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 described below. This section does not apply to Class 1 waters which are regulated by RMC 4-3- 090, Shoreline Master Program Regulations, or to Class 5 waters which are exempt. All other critical area regulations, including, but not limited to, flood hazard regulations.and wetland regulations, do apply to classified streams where applicable. a. Classification System: The following classification system is hereby adopted for the purposes ofregulating streams and lakes in the City. Stream and lake buffer widths are based on the following rating system: i. Class 1: Class I waters are perennial salmonid-bearing waters which are classified by the City and State as Shorelines of the State. ii. Class 2: Class 2 waters are perennial or intermittent salmonid-bearing waters which meet one or more of the following criteria: (a) Mapped on Figure Q4, Renton Water Class Map, as Class 2; and/or (b) Historically and/or currently known to support salmonids, including resident trout, at any stage in the species lifecycle; and/or (c) Is a water body (e.g., pond, lake) between one half(0.5) acre and twenty (20) acres in size. iii. Class 3: Class 3 waters are non-sahnonid-bearing perennial waters during years of normal rainfall, and/or mapped on Figure Q4, Renton Water Class Map, as Class 3. iv. Class 4: Class 4 waters are non-salmonid-bearing intermittent waters during years of normal rainfall, and/or mapped on Figure Q4, Renton Water Class Map, as Class 4. v. Class S: Class 5 waters are non-regulated non-salmonid-bearing waters which : (a) Flow within an artificially constructed channel where no naturally defined channel had previously existed; and/or (b) Are a surficially isolated water body less than one-half(0.5) acre (e.g., pond) not meeting the criteria for a wetland as defined in subsection M of this Section. The Upper Springbrook Creek project site is mapped as a class 2 stream by the City of Renton and meets the criteria of a class 2 stream since it supports coho salmon. Only those sections of the Shoreline Master Plan relevant to Class 2 streams are addressed throughout the remainder of this Consistency Determination. 3. Studies Required: d. Studies Waived: i. Standard Stream or Lake Study: May only be waived by the Administrator when the applicant provides satisfactory evidence that: (a) A road, building or other barrier exists between the water body and the proposed activity, or (b) The water body or required buffer area does not intrude on the applicant's lot, and based on evidence submitted, the proposal will not result in significant adverse impacts to nearby water bodies regulated under this Section; or ( c) Applicable data and analysis appropriate to the proposed project exists and an additional study is not necessary. Consistent-an Environmental Assessment has been prepared to comply with NEPA (National Environmental Policy Act). Much of the information required in a Standard Stream Study can be found in this document; therefore an additional study is not necessary. Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 iii. Stream or Lake Mitigation Plan: May only be waived when no impacts have been identified through a supplemental stream or lake study. Consistent-the Environmental Assessment identifies no significant negative impacts to the stream or the surrounding environment, thus mitigation will not be necessary. Overall conditions should improve as the stream will be moved away from a road, spawning gravel and large woody debris will be placed in the new channel, invasive vegetation will be removed from the site, and native vegetation will be planted along the new channel, in the old decommissioned channel, and in areas of disturbance. 4. General Standards for Class 2 to 4 Waters: a. Disturbance Prohibited: Streams and lakes and their buffer areas shall be undisturbed, except where the buffer is to be enhanced, or where exemptions allowed in subsection C of this Section are conducted, or where allowed to be altered in accordance with subsections L5, L 7 and LS of this Section. Where water body or buffer disturbance has occurred in accordance with exemption or development permit approval during construction or other activities, revegetation with native vegetation shall be required. Consistent-the project will enhance the buffer along the South side of the creek by relocating it and meandering it through the forested wetland to the North. The project includes the removal of invasive vegetation and planting of native emergents, shrubs, and trees in areas disturbed during construction. b. No Net Loss: There shall be no net loss of riparian area or shoreline ecological function resulting from any activity or land use occurring within the regulated buffer area. Consistent-the project is relocating the stream from its current location along a road to a meandered configuration through a forested area, and therefore riparian area and ecological function is expected to improve. 5. Stream/Lake Buffer Width Requirements: a. Buffers and Setbacks: i. Minimum Stream/Lake Buffer Widths: The minimum width of the required buffers shall be based upon the water body class. (a) Class 2: one hundred feet (100'). (b) Class 3: seventy five feet (75'). (c) Class 4: thirty five feet (35'). Consistent-the current buffer along the south bank of this section of Upper Springbrook Creek has a buffer width of only a couple of feet before the road. Relocating the stream away from the road will improve the functional buffer to an average of around 60 feet. The buffer along the north bank goes on for several hundred feet. Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 6. Stream or Lake Buffer Use Restrictions and Maintenance: Any activity or proposal subject to this subsection L shall comply with the following standards within required buffer areas: a. Preservation of Native Vegetation: Existing native vegetation shall be preserved to the extent possible, preferably in consolidated areas. Consistent-the project will remove invasive vegetation and plant native vegetation. Caution will be taken to minimize disturbance to native vegetation during construction. Disturbed areas will be planted with native vegetation following completion of construction. b. Revegetation Required: Where water body buffer disturbance has occurred in accordance with exemption or development permit approval or other activities, revegetation with native vegetation shall be required. Consistent-native vegetation will be planted on site following construction. c. Use of Native Species: When revegetation is required, native species, or other appropriate species naturalized to the Puget Sound region and approved by the Reviewing Official, shall be used. A variety of species shall be used which serve as food or shelter from climatic extremes and predators, and as structure and cover for reproduction and rearing of young. Consistent-a Corps botanist developed a list of native emergents, shrubs, and trees to be planted on site. d. Removal of Noxious Species: When required as a condition of approval, noxious or undesirable species of plants shall be removed or controlled so as to not compete with native vegetation. Consistent-noxious weeds will be removed from the site prior the planting native vegetation. For five years post-planting noxious weed removal will occur as part of routine maintenance. 8. Alterations Within Streams and Lakes or Associated Buffers. a. Transportation Crossings: i. Criteria for Administrative Approval of Transportation Crossings in Stream/Lake or Buffer Areas: Construction of vehicular or non-vehicular transportation crossings may be permitted in accordance with an approved supplemental stream/lake study subject to the following criteria: (a) The proposed route is determined to have the least impact on the environment, while meeting City Comprehensive Plan Transportation Element requirements and standards in RMC 4-6-060; and Consistent-an Environmental Assessment has been prepared with a determination of insignificant impacts to the environment. The project will replace a 30 inch diameter pipe culvert under South 55th Streetreet with a ten foot wide by 4 foot tall box culvert which will meet the requirement of the Washington Department of fish and Wildlife Culvert Design Manual (2003) allowing for improved fish access to higher quality upstream habitat. Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 (b) The crossing minimizes interruption of downstream movement of wood and gravel; and Consistent-the project will replace a 30 inch diameter pipe culvert under South 55th Street with a ten foot wide by 4 foot tall box culvert, thus allowing for significantly more movement of wood and gravel. ( c) Transportation facilities in buffer areas shall not run parallel to the water body; and Consistent-crossing is perpendicular to stream (d) Crossings occur as near to perpendicular with the water body as possible; and Consistent-crossing is perpendicular to stream ( e) Crossings are designed according to the Washington Department of Fish and Wildlife Fish Passage Design at Road Culverts, 1999, and the National Marine Fisheries Service Guidelines for Salmonid Passage at Stream Crossings, 2000, as may be updated, or equivalent manuals as determined by the Responsible Official; and Consistent-the project will replace a 30 inch diameter pipe culvert under South 55th Street with a ten foot wide by 4 foot tall box culvert which will meet the requirement of the Washington Department offish and Wildlife Culvert Design Manual (2003). (f) Seasonal work windows are determined and made a condition of approval; and Consistent-all in-water work will be done in the fish window established by Washington Department of Fish and Wildlife (July 1 through September 30). (g) Mitigation criteria of subsection L3c(ii) of this Section are met. Consistent-this project will result in an overall gain in aquatic habitat functions and values by relocating the stream away from the road and through a forested corridor, placing spawning gravel and large woody debris in the new channel, removing invasive vegetation and planting native species, and replacing the culvert underneath South ss'h Street. Therefore the project is self-mitigating. e. Alterations of Streams and Lakes or Associated Buffers -Stream Relocation: i. Administrative Approval of Stream Relocation: Stream relocation may be allowed when analyzed in an accepted supplemental stream or lake assessment, and when the following criteria and conditions are met: (a) Criteria: Stream relocation may only be permitted if associated with: Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 ( 1) A public flood hazard reduction/habitat enhancement project approved by appropriate State and/or Federal agencies; or (2) Expansion of public road or other public facility improvements where no feasible alternative exists; or (3) A public or private proposal restoring a water body and resulting in a net benefit to on-or off-site habitat and species. Consistent-the relocation of the stream away from South 55th Street through a forested wetland in a more natural channel is a habitat enhancement. (b) Additional Conditions: The following conditions also apply to any stream relocation proposal meeting one or more of the above criteria: ( 1) Buffer widths shall be based upon the new stream location; provided, that the buffer widths may be reduced or averaged if meeting criteria of subsection L5c or L5d of this Section or subsection L8e(i)(b)(2) of this Section. Where minimum required buffer widths are not feasible for stream relocation proposals that are the result of activities pursuant to criteria in subsections L8e(i)(a)(l) and (2) of this Section, other equivalent on-or off-site compensation to achieve no-net-loss of riparian function is provided; (2) When Class 4 streams are proposed for relocation due to expansions of public roads or other public facility improvements per subsection L8e(i)(a)(2) of this Section, the buffer area between the facility and the relocated stream shall not be less than the width prior to the relocation. The provided buffer between the facility and the relocated stream shall be enhanced or improved to provide appropriate function given the class and condition of the stream; or if there is no buffer currently, other equivalent on-or off-site compensation to achieve no net loss of riparian function is provided. (3) Applicable mitigation criteria of subsection L3c(ii) of this Section must be met. ( 4) Proper notifications and records must be made of stream relocations, per subsection D3b of this Section, Information to be Obtained and Maintained, and subsection D3c of this Section, Alterations of Watercourses, in cases where the stream/lake is subject to flood hazard regulations of this Section, as well as subsection F8 of this Section if neighboring properties are impacted. Consistent-the proposed channel relocation will have a wider buffer than the stream does at its current location, and since the project is an improvement, no mitigation is required. The stream is not subject to flood hazard regulations. M. WETLANDS: 1. Applicability: The wetland regulations apply to sites containing or abutting wetlands as described below. Category 3 wetlands, less than two thousand two hundred (2,200) square feet in area, are exempt from these regulations if they meet exemption criteria in subsection C of this Section. Final ·Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 a. Classification System: The following classification system is hereby adopted for the purposes ofregulating wetlands in the City. Wetlands buffer widths, replacement ratios and avoidance criteria shall be based on the following rating system: i. Category 1: Category 1 wetlands are wetlands which meet one or more of the following: (a) The presence of species listed by Federal or State government as endangered or threatened, or the presence of essential habitat for those species; and/or (b) Wetlands having forty percent (40%) to sixty percent (60%) permanent open water (in dispersed patches or otherwise) with two (2) or more vegetation classes; and/or (c) Wetlands equal to or greater than ten (10) acres in size and having three (3) or more vegetation .classes, one of which is open water; and/or ( d) The presence of plant associations of infrequent occurrence; or at the geographic limits of their occurrence; and/or ii. Category 2: Category 2 wetlands are wetlands which meet one or more of the following criteria: (a) Wetlands that are not Category I or 3 wetlands; and/or (b) Wetlands that have heron rookeries or osprey nests, but are not Category 1 wetlands; and/or ( c) Wetlands of any size located at the headwaters of a watercourse, i.e., a wetland with a perennial or seasonal outflow channel, but with no defined influent channel, but are not Category 1 wetlands; and/or (d) Wetlands having minimum existing evidence of human-related physical alteration such as diking, ditching or channelization; and/or iii. Category 3: Category 3 wetlands are wetlands which meet one or more of the following criteria: (a) Wetlands that are severely disturbed. Severely disturbed wetlands are wetlands which meet the following criteria: (1) Are characterized by hydrologic isolation, human-related hydrologic alterations such.as diking, ditching, channelization and/or outlet modification; and (2) Have soils alterations such as the presence of fill, soil removal and/or compaction of soils; and (3) May have altered vegetation. (b) Wetlands that are newly emerging. Newly emerging wetlands are: (1) Wetlands occurring on top of fill materials; and (2) Characterized by emergent vegetation, low plant species richness and used minimally by wildlife. These wetlands are generally found in the areas such as the Green River Valley and Black River Drainage Basin. (c) All other wetlands not classified as Category I or 2 such as smaller, high quality wetlands. Consistent-The wetland to the North of Upper Springbrook Creek, which is the location of the proposed new channel, is classified as a category three wetland since it shows evidence of being severely disturbed due to alterations such as road placement and outlet modification. Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 2. General Standards for Permit Approval: Permit approval by the Reviewing Official for projects involving regulated wetlands or wetland buffers shall be granted only if the approval is consistent with the provisions of this Section. Additionally, approvals shall only be granted if: a. A proposed action avoids adverse impacts to regulated wetlands or their buffers or takes affirmative and appropriate measures to minimize and compensate for unavoidable impacts; and b. The proposed activity results in no net loss of regulated wetland area, value, or function in the drainage basin where the wetland is located; or c. A variance process is successfully completed to determine conditions for permitting of activity requested including measures to reduce impacts as appropriate. Consistent-the proposed stream alignment through the adjacent forested wetland will have insignificant impacts, as determined by the Environmental Assessment, and will result in a net gain in aquatic habitat function and value by relocating the stream way from the road, placing gravel and large woody debris in the new channel, removing invasive vegetation, and planting native emergents, shrubs, and trees along the stream, in the decommissioned channel, and in areas of disturbance. 3. Study Required: a. When Study Is Required: Wetland assessments are required as follows: i. Wetland Classification: The applicant shall be required to conduct a study to determine the classification of the wetland if the subject property or project area is within one hundred feet (I 00') of a wetland even if the wetland is not located on the subject property but it is determined that alterations of the subject property are likely to impact the wetland in question or its buffer. If there is a potential Category I or 2 wetland within three hundred feet (300') of a proposal, the City may require an applicant to conduct a study even if the wetland is not located on the subject property but it is determined that alterations of the subject property are likely to impact the wetland in question or its buffer. Consistent-a wetland report was prepared by a qualified Corps botanist. The wetland was rated as a category 3 using the City of Renton 's criteria. ii. Wetland Delineation: A wetland delineation is required for any portion of a wetland on the subject property that will be impacted by the permitted activities. Consistent-a wetland delineation was done on the wetland to the north of the stream and it was determined to all be wet. 4. Delineation of Regulatory Edge of Wetlands: a. Methodology: For the purpose ofregulation, the exact location of the wetland edge shall be determined by the wetlands specialist hired at the expense of the applicant through the performance of a field investigation using the procedures provided in the following manual: Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 Washington State Wetlands Identification and Delineation Manual, Washington State Department of Ecology, March 1997, Ecology Publication No. 96-94. b. Delineations -Open Water: Where wetlands are contiguous with areas of open freshwater, streams, or rivers, the delineation shall be consistent with the Washington State Wetlands Rating System: Western Washington, Second Edition, Washington State Department of Ecology, August 1993, Publication No. 93-74, Appendix 5, or another accepted Federal or State methodology, subject to City review. c. Adjustments to Delineation by City: Where the applicant has provided a delineation of the wetland edge, the City shall review and may render adjustments to the edge delineation. In the event the adjusted edge delineation is contested by the applicant, the City shall, at the applicant's expense, obtain the services of an additional qualified wetlands specialist to review the original study and render a final delineation. Consistent-the entire swath of green space North of this section of Upper Springbrook Creek is mapped as wetland by the City of Renton and has been confirmed by a Corps of Engineers botaniStreet 6. Wetland Buffers: a. B offers Required: . i. Wetland buffer zones shall be required of all proposed regulated activities abutting regulated wetlands. ii. Any wetland created, restored, or enhanced in conjunction with creation or restoration as compensation for approved wetland alterations shall include the standard buffer required for the class of the wetland being replaced. iii. All required wetland buffer zones shall be retained in their natural condition. Category 3 wetland buffers of twenty five feet (25') require the buffers be fully vegetated with native species or restored; otherwise increased buffer widths to protect functions and values may be required. iv. Where buffer disturbance has occurred during construction or other activities, revegetation with native vegetation may be required. Consistent-the buffer surrounding the wetland with not change by relocating the stream. All disturbed areas will be planted with native vegetation. 8. Wetland Changes -Alternative Methods of Development: If wetland changes are proposed for a non-exempt activity, the applicant shall evaluate alternative methods of developing the property using the following criteria in this order and provide reasons why a less intrusive method of development is not feasible. In determining whether to grant permit approval per subsection M2 of this Section, General Standards for Permit Approval, the Reviewing Official shall make a determination as to whether the feasibility of less intrusive methods of development have been adequately evaluated and that less intrusive methods of development are not feasible: a. Avoid any disturbances to the wetland or buffer; b. Minimize any wetland or buffer impacts; c. Restore any wetlands or buffer impacted or lost temporarily; and Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 d. Compensate for any permanent wetland or buffer impacts by one of the following methods: i. Restoring a former wetland and provide buffers at a site once exhibiting wetland characteristics to compensate for wetlands lost; ii. Creating new wetlands and buffers for those lost; and iii. In addition to restoring or creating a wetland, enhancing an· existing degraded wetland to compensate for lost functions and values. Consistent-the only permanent disturbance to the wetland will be in the area where the new channel will be located, which will be approximately 0.19 acres. However, there will be an overall gain in habitat value and function both in the new channel and within the wetland as invasive plants will be removed and replaced with native emergents, shrubs, and trees. The old decommissioned channel will also have native vegetation removed and planted with a mixture of native species and will, therefore, function as part of the wetland. 9. Compensating for Wetlands Impacts: a. Goal: The overall goal of any compensatory project shall be no net loss of wetland function and acreage and to strive for a net resource gain in wetlands over present conditions. The concept of "no net loss" means to create, restore and/or enhance a wetland so that there is no reduction to total wetland acreage and/or function. b. Plan Requirements: The applicant shall develop a plan that provides for land acquisition, construction, maintenance and monitoring of replacement wetlands that recreate as nearly as possible the wetland being replaced in terms of acreage, function, geographic location and setting, and that are equal to or larger than the original wetlands. c. Plan Performance Standards: Compensatory mitigation shall follow an approved mitigation plan pursuant to subsections M8 to Ml O of this Section and shall meet the minimum performance standards in subsection F8 of this Section. d. Acceptable Mitigation -Permanent Wetland Impacts: Any person who alters regulated wetlands shall restore or create equivalent areas or greater areas of wetlands than those altered in order to compensate for wetland losses. Enhancement of wetlands may be provided as mitigation if it is conducted in conjunction with mitigation proposed to create or restore a wetland in order to maintain "no net loss" of wetland acreage. Subsections Ml 0 through Ml 2 provide further detail on wetland restoration, creation, and enhancement. e. Restoration, Creation, or Combined Enhancement Required -Compensation for Permanent Wetland Impacts: As a condition of any permit allowing alteration of wetlands and/or wetland buffers, or as an enforcement action, the City shall require that the applicant engage in the restoration or creation of wetlands and their buffers (or funding of these activities) in order to offset the impacts resulting from the applicant's or violator's actions. Enhancement in conjunction with restoration or creation may be allowed in order to offset the impacts resulting from an applicant's actions. Enhancement is not allowed as compensation for a violator's actions. f. Compensating for Temporary Wetland Impacts: Where wetland disturbance has occurred during construction or other activities, see subsection C5f(ii) of this Section. g. Mitigation Bank Agreement -Glacier Park Company: Pursuant to the Wetland Mitigation Bank Agreement between the City and the Glacier Park Company, King County ~~~~~~~~~~~~~~~~~~~~~~~~~~~~78 Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 recording number 9206241805, wetland alteration and wetland mitigation shall be conducted in accordance with the agreement. Consistent-since there will be a net gain in both stream and wetland habitat function and value from the project no mitigation/compensation beyond what is already proposed in the project (removal of invasive vegetation, planting of native emergents, shrubs, and trees, replacing the culvert underneath South 55th Street, moving the stream from the road and meandering it through the forested wetland, and placing spawning gravel and large woody debris in the new channel) is necessary. 12. Wetland Enhancement: a. Enhancement Proposals-Combined with Restoration and Creation: Any applicant proposing to alter wetlands may propose to enhance an existing degraded wetland, in conjunction with restoration or creation of a wetland in order to compensate for wetland losses. Wetland enhancement shall not be allowed as compensation if it is not accomplished in conjunction with a proposal to restore or create a wetland. Consistent-the project itself will enhance an existing wetland by removing invasive vegetation and planting native emergents, shrubs, and trees. No additional or off-site enhancement is required. Based on the above evaluation, it is determined that the proposed rehabilitation activities comply with the policies, general conditions, and activities as specified in the King County Shoreline Master Program. The proposed action is considered to be consistent to the maximum extent practicable with the State of Washington Shoreline Management Program and policies and standards of the King County Shoreline Master Program. Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 AppendixH SHPO Concurrence and Letter and Emails to the Tribe Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 STATE OF WASHINGTON DEPARTMENT OF ARCHAEOLOGY & HISTORIC PRESERVATION 1063 5. Capitol Way, Suite 106 • Olympia, Washington 98501 Mailing address: PO Box 48343 • Olympia, Washington 98504-8343 (360) 586-3065 • Fax Number (360) 586-3067 • Website: www.dahp.wa.gov May 3, 2010 Mr. Aaron Naumann Environmental Resources Section Seattle District, Corps of Engineers PO Box 3755 Seattle, Washington 98124-3755 Dear Mr. Naumann RE: Upper Springbrook Creek Realignment & Rehabilitation Project Log No.: 050310-02-COE-S Thank you for contacting our department. We have reviewed the professional archaeological survey report you provided for the proposed Upper Springbrook Creek Realignment & Rehabilitation Project in King County, Washington. We concur with your determination of No Historic Properties Affected. We concur with the stipulation for professional archaeological monitoring for excavations below 3 feet. Please provide the monitoring reports when available. We also would appreciate receiving any correspondence or comments from concerned tribes or other parties that you receive as you consult under the requirements of 36CFR800.4(a)(4). These comments are based on the information available at the time of this review and on the behalf of the State Historic Preservation Officer in conformance with Section 106 of the National Historic Preservation Act, as amended, and it's implementing regulations 36CFR800. Should additional information become available, our assessment may be revised. Thank you for the opportunity to comment on this undertaking and a copy of these comments should be included in subsequent environmental documents. Sincerely, Robert G. Whitlam, Ph.D. State Archaeologist (360) 586-3080 email: rob.whitlam@dahp.wa.gov ~.~EPARTMENT OF ARCHAEOLOGY & HISTORIC PRESERVATION 1 · -Protect the Past, Shape /he Fu!ure REPLY TO ATTENTION OF DEPARTMENT OF THE ARMY SEATTLE DISTRICT, CORPS OF ENGINEERS P.O. BOX 3755 SEATILE, WASHINGTON 98124-3755 Environmental Resources Section Melissa Calvert, ATOM (Cultural Resources Manager) Philip Starr Building 39015 172nd Ave SE Auburn, WA 98092 SUBJECT: Request for knowledge of; or concerns with, Historic Properties for the proposed Upper Springbrook Creek Channel Realignment and Rehabilitation Project, King County Dear Ms. Calvert: The U.S Army Corps of Engineers (Corps) and the City of Renton propose to realign and rehabilitate a portion of the Upper Springbrook Creek currently parallel to S. 55th St. in a roadside ditch. The proposed action includes: I) replacing the culvert underneath S. 55th St. with an appropriately designed box culvert as approved by the State of Washington Department of Fish and Wildlife (WDFW) for fish passage, 2) realigning the channel through an adjacent forested wetland that lies to the north of S. 55th St. in order to create complex habitat for aquatic biota. This project has been determined to be a Federal undertaking of the type that might affect historic properties and therefore must comply with the policies therein the National Environmental Policy Act (NEPA) and Section 106 of the National Historic Preservation Act (16 u.s.c. 470). Corps archaeologists conducted an archaeological and historical investigation of the project area and did not identify any significant prehistoric or historic resources during the survey. All ten shovel test pits excavated during the cultural resources survey were negative for cultural materials and indicated thick alluvial deposits were present within the APE. However, it is reported in the literature that the general vicinity of the project area is composed of rapidly aggregated alluvial deposits, which means there is the potential for deeply buried native sediments within the area of potential effect (APE). As a result, Corps archaeologists recommend any excavation conducted beyond the extent of these shovel test pits, or a depth of approximately 3 feet, be monitored by a professional archaeologist. To further identify historic properties, Section 106 of the National Historic Preservation Act (NHP A or the Act) of 1966, as amended (36 CFR 800.4[ a][3]), requires Federal agencies to seek information from tribes likely to have knowledge of; or concerns with, historic properties within the project's APE. We are specifically seeking assistance in identifying properties that may be ofreligious or cultural significance and may be eligible for listing in the National Register of Historic Places (NRHP), including Traditional Cultural Properties (TCPs). Specific -2- guidance concerning the Corps' obligation to contact your tribe regarding this issue is found at 36 CFR 800.4(a)(4), which states that the agency official shall: (4) Gather information from any Indian tribe or Native Hawaiian organization identified pursuant to Sec. 800.3(!) to assist in identifying properties, including those located off tribal lands, which may be of religious and cultural significance to them and may be eligible for the National Register, recognizing that an Indian tribe or Native Hawaiian organization may be reluctant to divulge specific infonnation regarding the location, nature, and activities associated with such sites. The agency official should address concerns raised about confidentiality pursuant to Sec. 800.11 ( c ). We appreciate any assistance you can provide us in our efforts to comply with Section 106 of the NHP A. Please be assured that the Corps will treat any information you decide to share with us with the degree of confidentiality that is required in Section 800.11( c) of the NHP A, or with any other special restrictions you may require. In order to fulfill these obligations we request that you provide comments at your earliest convenience A copy of the assessment and project plan has been included for your perusal. If you have any questions or require additional information, please feel free to contact me at (206) 764-4476 or by e-mail at aaron.j.naurnann@usace.army.mil. Enclosure Cc (with enclosures): Laura Murphy Philip Starr Building 39015 172nd Ave SE Auburn, WA 98092 Sincerely, Aaron J. Naumann, Corps Archaeological Technician, MA, RPA Environmental Resources Section Dated 5/61201 O Melissa and Laura, I am sending this e-mail as a follow up and an update to a previous e-mail I send on April 29, 2010 concerning the Upper Springbrook Creek Channel Realignment and Rehabilitation Project near Kent, WA. The Corps has since received concurrence from the State Historic Preservation Officer on the determination of "No Historic Properties Effected, pending monitoring· by a profession archaeologist". This project has a particularly tight schedule due to the fact it involves federal stimulus money. If you could please comment at your earliest convenience it would be greatly appreciated. I apologize for the short lead time on this project and am happy to answer any questions you may have regarding it. Sincerely, Aaron Naumann, MA, RPA, Corps Archaeological Technician Tel: (206. 764.4476 Dated 4/29/1 O Melissa and Laura, The United States Corps of Engineers (Corps) has a project in need of your comments that is under a fairly tight deadline. It is a fish restoration project near Kent on a small parcel of land with no known associated cultural materials. Liz Ellis and I conducted the cultural resources review, and I wrote up the report (see attached). We did not find any evidence of any cultural materials in our archival research or during the actually archaeological survey. However, we recommend monitoring of the project because of the potential for deeply buried deposits to be present in the area. We would be very appreciative if you could review the attached report and provide us with your opinion/decision regarding this project by May 7th. I apologize for the short lead time and will try calling you later this afternoon. Sincerely, Aaron Naumann, MA, RPA, Corps Archaeological Technician Tel: (206. 764.4476) Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 Appendix I Public Comments Received 4/15/10 Comment-Hi Chemine: Some feedback on the EA document -would be helpful to have the location of Springbrook listed in the document. Only through closely reading the document can one find out that it is a part of the Duwamish system. Thanks. Response-Indicated under the "Project Location" section that the stream is part of the Green River Basin. "Hydrology" section gives and extensive description of the stream configuration and its link to the Green River. Final Environmental Assessment Upper Springbrook Creek Channel Realignment and Rehabilitation May 2010 95% DRAFT DESIGN AND CONSTRUCT! Bl LITY REPORT City of ,:,~ t -ncn. on Pianninq D1·v1·Q· -~1011 AFR 1 9 2010 GREEN DUWAMISH RIVER ECOSYSTEM RESTORATION -UPPER SPRINGBROOK CREEK PROJECT Prepared for U.S. Anny Corps of Engineers 4735 East Marginal Way South Seattle, Washington 98134 Prepared by Anchor QEA, LLC 1605 Cornwall Avenue Bellingham, Washington 98225 March 2010 TABLE OF CONTENTS 1 INTRODUCTION AND PURPOSE ....................................................................................... 1 2 DESIGN ANALYSIS ............................................................................................................... 2 2.1 Evaluation of Existing Conditions ............... : ................................................................... 2 2.2 Proposed Conditions Model Development .................................................................... .4 2.3 Proposed Channel Realignment ..................................................................................... .4 2.3.1 Channel Design ......................................................................................................... .4 2.3.2 Imported Sediment Grain Size Distribution Evaluation .......................................... 6 2.3.3 Fish Habitat Evaluation ............................................................................................ 16 2.4 Proposed In-Channel Large Woody Debris Placement ............................................... 21 2.4.1 L WD Log Qµantities and Locations ........................................................................ 22 2.4.2 In-Channel L WD Placement Types ........................................................................ 23 2.4.3 L WD Stability and Expected Scour ......................................................................... 24 2.5 Proposed Floodplain Leg Placements and Plantings .................................................... 25 2.5.1 Floodplain Log Model Development and Analysis ................................................. 26 2.5.2 Floodplain Log Size Specification ............................................................................ 27 2.6 Proposed Culvert Replacement ..................................................................................... 27 2.6.1 Culvert Specifications ...... , ........................................................................................ 27 2.6.2 Inlet/Outlet Design and Specifications .................................................................... 30 2.6.3 Fish Passage Evaluation ............................................................................................ 30 2.6.4 Road Grade Replacement and Utility Relocation ................................................... 32 3 CONSTRUCTABILlTY ANALYSIS ..................................................................................... 33 3.1 Reco=ended Construction Equipment ...................................................................... 33 3.2 Mobilization, Site Access and Staging, and Site Preparation ....................................... 34 3.3 Demolition ...................................................................................................................... 35 3.4 New Channel Construction ........................... , ......................................................... : ..... 36 3.5 Large Woody Debris Placements .................................................................... , ............. 37 3.5.1 In-Channel Large Woody Debris Placements ........................................................ 37 3.5.2 Floodplain Log Placements ...................................................................................... 38 3.6 Culvert Construction ..................................................................................................... 39 3. 7 Creek Flow Ramping and Fish Rescue and Recovery ................................................. .41 95% Draft Design and Constroetllbility Report Upper Springbrook Creek Project i March2010 090202-01 • Table of Contents 3.8 Decommissioning of the Existing Channel ... , ................................................ ; ............. .42 3.9 Construction Decommissioning and Site Restoration ................................................. 42 3.10 Best Management Practices .......................................................................................... .42 3.10.1 Spill Prevention ....................................................................................................... .43 3.10.2 Erosion and Sediment Control. ..............................................................................•. 43 4 IJMITATIONS ................................................ , .................................................................... 45 5 REFERENCES .............................•.•......................................................•............................... 46 List of Tables Table 1 Table 2 Table3 Table4 Tables Table6 Table 7 Table8 Table9 Table 10 Table 11 Table 12 Table 13 Table 14 Table 15 Design Flow Hydrology ........................................................................................ 3 Recommended Natural Sediment Distribution Ratios ....................................... 6 WDFW Recommended Coho Spawning Sediment GSD ................................... 7 Imported Channel Sediment GSD ..................................................................... 10 Imported Channel Sediment GSD Specification ............................................... 10 Spawning and Rearing Criteria .......................................................................... 16 Spawning and Rearing Criteria, Model Su=ary (1) ....................................... 17 Spawning and Rearing Criteria, Model Su=ary (2) ....................................... 21 Recommended Natural Conditions L WD Quantities ........................ : .............. 22 Proposed L WD Quantities and Volumes ........................................................... 23 HEC-RAS Lateral Weir Analysis Su=ary ...................................................... 26 Replacement Culvert Specifications .................................................................. 29 Culvert Adult Fish Passage Design Criteria ...................................................... 31 Proposed Culvert Model Results ........................................................................ 31 Recommended Construction Equipment .......................................................... 34 List of Charts Chart 1 Chart2 Chart3 Chart4 Threshold Grain Size ( 48 cfs) .............................................................................. 7 Threshold Grain Size (88 cfs) .............................................................................. 8 Threshold Grain Size (121 cfs) .............................................. ; ............................. 9 Sediment Grain Mobility (48 cfs) ...................................................................... 12 95% Draft Design and Cnnstruct:E.bility Report Upper Springbrook Creek Project jj March2010 090202-01 ChartS Chart6 Chart 7 Chart8 Chart9 ChartlO Chart 11 Chart 12 Table of Contents Sediment Grain Mobility (88 cfs) ...................................................................... 13 Sediment Grain Mobility (120 cfs) .................................................................... 14 Sediment Transport Simulation ........................................................................ 15 Water Depth in Proposed Channel at Low Flows (3.2 cfs and 4.5 cfs) ........... 17 Velocities in Proposed Channel at Low Flows (3.2 cfs and 4.5 cfs) ................ 18 Habitat Model Results (3.2 cfs) ......................................................................... 19 Habitat Model Results (4.5 cfs) ......................................................................... 20 Habitat Model Results (10 cfs) .......................................................................... 20 List of Appendices Appendix A HEC-RAS Proposed Hydraulic Model Results Appendix B Floodplain Log Placement Specification Calculations Appendix C Sediment Transport Analysis 95% Draft Design and Construct11bility Report Upper Springbrook Creek Project iii March2010 090202-01 LIST OF ACRONYMS AND ABBREVIATIONS BAGS BFW BMP cfs ems Corps cy DSO Dxx EGL GSD H:V HDPE HEC-RAS kN LWD m mm Project PVC SR SWDM TESC WDFW WSDOT Bed.load Assessment for Gravel-bed Streams bankfull width best management practice cubic feet per second cubic meter per second U.S. Army Corps of Engineers cubic yard median grain size (sediment) XX% passing grain size (sediment) energy grade line grain size distribution (sediment) horizontal to vertical high-density polyethylene Hydraulic Engineering Center's River Analysis System kilonewtons large woody debris meter millimeter Upper Springbrook Creek Project polyvinyl chloride State Route Surface Water Design Manual (King County 2005) Temporary Erosion and Sedimentation Control Washington Department of Fish and Wildlife Washington State Department of Transportation 95% Draft Design and Constructability Report Upper Springbrook Creek Project iv Table of Contents March2010 090202-01 1 INTRODUCTION AND PURPOSE The Upper Springbrook Creek Project (Project) is located within the City of Renton in King County, Washington. Plan Sheets 1 and 3 illustrate the Project location and existing condition, respectively. The Project will realign a portion of the existing stream channel between the South 55th Street and State Route (SR) 167 crossings to provide a more naturally functioning system and improve habitat conditions for salmonids and other fish species that utilize the stream. The Project will also replace an existing 30-inch culvert that crosses South 55th Street at the upstream end of the Project area. The proposed replacement culvert will improve fish passage, increase hydraulic capacity, and allow for natural sediment transport dynamics. Under existing conditions, the channel is a primarily linear, uniform roadside ditch that runs parallel to South 55th Street on the north side through the Project extent. The proposed design will permanently relocate approximately 900 feet of the existing channel from its current channelized planform to a new alignment through the existing floodplain to the north. In addition to excavation of the proposed channel alignment, the Project will include placement of large woody debris (L WD) in the channel, logs and plantings in the existing floodplain, and replacement of the South 55th Street culvert and associated headwalls. These features will work collectively to provide and maintain salmonid spawning and rearing habitat through the Project site. Implementation of the Project is scheduled to occur during the summer of 2011. 95% Draft Design and Constructability Report Upper Springbrook Creek Project 1 March2010 090202-01 2 DESIGN ANALYSIS A variety of qualitative and quantitative evaluations were performed to formulate the Project design and specifications. The following sections summarize the analyses performed as part of the 95 percent design development including relevant supporting data and calculations. The design analysis is divided into the following elements: evaluation of existing conditions, development of a proposed conditions hydraulic model, design of the proposed channel, design of in-channel L WD, design of floodplain log placements, and design of a replacement culvert under South 55th Street. 2.1 Evaluation of Existing Conditions Ground survey data collected in 2008 and 2009 (DHA 2008) and photogrammetric topography data provided by the City of Renton were used to develop an existing conditions surface of the Project area. Hydrology data including peak and low summer flows were obtained from a previous study completed for replacement of the SR 167 culvert at the downstream end of the Project area (DEA 2001). Additional design flows for the 1-year and 5-year flow events that were not available in the report were estimated by the U.S. Army Corps of Engineers (Corps) from the values presented in the 2001 Hydraulic Report (DEA 2001). Table l lists the design flows used in the hydraulic analysis. The Hydraulic Engineering Center's River Analysis System (HEC-RAS) model was used to evaluate hydraulic conditions for existing and proposed site conditions (USACE 2008). Detailed information describing the development of the HEC-RAS model geometry is available in the 35 Percent Design and Constructability Report (Anchor QEA 2010a). 95% Draft Design and Constmrubility Report Upper Springbrook Creek Project 2 March2010 090202-01 Design Analysis Table 1 Design Flow Hydrology ' Flow Event Discharge (cfs) Low (current) 3.2 Low (future) 4.5 1-year 48 2-year 70 5-year 84 10-year 88 25-year 99 SO-year 110 100-year 121 Evaluation of the existing topography data indicate that the ground surface north of the existing channel drops in elevation with increasing distance from the existing right channel bank. This observation was consistent throughout the floodplain area north of the Project site. The existing conditions HEC-RAS model shows that overtopping of the right bank occurs throughout a majority of the Project area during a 2-year return interval [approximately 70 cubic feet per second (cfs)], with slightly less overtopping occurring at a I- year return interval (approximately 48 cfs) (Appendix A). The 2001 Hydraulic Report confirms that water overtopping the banks of Upper Springbrook Creek flows through the north floodplain and ponds on the west side of SR 167 before eventually flowing north to No Name Creek (DEA 2001). Observation of floodplain topography shows a depression west of SR 167 approximately 1,400 feet north of the existing channel where water likely accumulates. Based on these findings, it is possible that significant volumes of water are currently lost to the floodplain during flood events. These floodwaters may strand juvenile fish and contribute to flooding off site. Understanding the complications of the existing conditions is critical to alternatives evaluation and design development to minimize potential flooding and fish stranding that may occur after Project implementation. 95% Draft Design and Constructability Report Upper Springbrook Creek Project 3 Match2010 090202-01 Design Analysis 2.2 Proposed Conditions Model Development The proposed conditions hydraulic model geometry was extracted from an AutoCAD Civil 3D surface incorporating the proposed channel realignment. The existing channel was blocked at the upstream end of the model to simulate the blockage at this location, and the proposed culvert and associated re-grading was incorporated into the model geometry. The cross-sections were truncated at the Project limit and a lateral weir was built into the model at the northern extent of the model to evaluate the effect oflog placements in the floodplain. The proposed model results were used to evaluate the suitability of the proposed channel and floodplain improvements with respect to flow conveyance, floodplain connectivity, bank overtopping, and depth-averaged velocities through the new channel and culvert. Sediment transport dynamics were a key element in this evaluation. The existing and proposed models were run with the same peak flow events and cross-section locations to allow comparison of pre-and post-Project conditions, and to provide output to be used in the design analysis of the proposed structural elements. The specific analyses performed for each design element are discussed in detail within the following sections. 2.3 Proposed Channel Realignment 2.3.1 Channel Design The proposed channel alignment is approximately 970 feet long. The typical cross-sectional geometry is trapezoidal with 3 horizontal to 1 vertical (3H: 1 V) side slopes, a 6-foot bottom width, and an average bank full depth of approximately 1.5 feet. The channel will be over- excavated to allow for the placement of imported sediments along the channel bottom and sides. The planfomi of the channel is sinuous and the channel alignment primarily follows low areas within the existing topography within the 100-foot-wide drainage easement, minimizing cut volumes and grading activities through the floodplain. The proposed channel alignment effectively relocates the channel reach away from South 55th Street, enhances salmonid habitat, enhances and protects riparian conditions, and is feasible in terms of constructability and cost. Plan Sheets 4 through 7 and 10 through 17 show the proposed channel design details. 9596 Draft Design and Construrubility Report Upper Springbrook Creek Project 4 March2010 090202-01 Design Analysis Plan Sheet 4 illustrates the proposed channel alignment .. The new channel alignment begins in an existing pool at the downstream end of the existing culvert (Existing Culvert 3) at the east end of the Project reach. The pool elevation roughly establishes the upstream grade of the new channel and the discharge invert elevation of the replacement culvert. The proposed channel alignment gradient (slope) is approximately 1.40 percent from approximately Station 0+00 to 7+31 and 1.82 percent from approximately Station 7+30 to the downstream end of the culvert. The proposed channel gradient is similar to the average grade of the existing channel and roughly tied into existing bed elevations at the upstream and downstream ends of the proposed alignment. Areas disturbed by construction of the channel that are not improved, such as by transport of materials within the site, will be covered in coir fabric to aid in short-term stabilization. Coir fabric will be installed along the banks of the new channel below the imported channel sediment and extend upland of the new channel as necessary. Long-term stabilization of the channel banks will be established by riparian plantings. The cross-sectional geometry of the channel was designed to mimic the geometry of a more naturally functioning segment of the creek upstream of the Project site, and to effectively contain lower peak flow hydrology with adequate flow depths and velocities that are consistent with salmonid habitat criteria. The channel sinuosity and alignment within the existing floodplain promotes hydraulic complexity, minimizes the removal of mature riparian vegetation, and reduces the volume of earthwork required by following low areas within the existing topography. The bankfull channel depth is limited to 1.5 feet through the majority of the new channel extent. This is due to the low existing floodplain topography and existing bed elevations at the upstream (Existing Culvert 1) and downstream. (Existing Culvert 3) culverts. Model results for the proposed conditions show overtopping of the banks begins to occur near the 1-year recurrence discharge throughout a majority of the Project reach. · Concerns related to the loss of bankfuUflows across the floodplain will be minimized by incorporating logs and . . live plantings into the floodplain, discussed in Section 2.5. 95% Draft Design and Constructa.bility Report Upper Springbrook Creek Project 5 March2010 090202-01 Design Analysis 2.3.2 Imported Sediment Grain Size Distribution Evaluation Imported sediment for the proposed channel is intended to enhance spawning and rearing habitat for salmonids while maintaining acceptable channel stability. This evaluation involved an analysis of relative sediment mobility under various design flows and their conformance to recommendations from government agencies. The selected sediment needs to be sufficiently mo bile such that it will provide clean spawning substrate but not excessively mobile so as to require undue spawning sediment augmentation. Recommendations from government agencies included both general stream sediment distribution ratios and specific gain sizes for habitat function. Table 2 shows recommended natural stream sediment distribution ratios. These values are intended to provide a starting point for development of a synthetic grain size distribution (GSD) for stream beds. The lower portion of the gradation is intended to sufficiently fill the interstices to promote surface flow during low flow. The upper portion of the gradation is intended to provide bed surface diversity. Table 2 Recommended Natural Sediment Distribution Ratios Distribution Ratio Recommended Value D,JD100 0.4 D .. fDso 2.5 D,./D10 8.0 Source: WDFW (2003) In addition to general sediment distribution ratios, specific GSD recommendations are provided for target species habitat function. Table 3 shows a recommended GSD for spawning sediment used by coho. 95% Draft Design and Constmct11bility Report Upper Springbrook Creek Project 6 March2010 090202-01 Design Analysis Table 3 WDFW Recommended Coho Spawning Sediment GSD Grain Size Class Size (mm) Size (in) D100 150 5.9 D01 100 3.9 D74 50 2.0 o,, . 13 0.51 Dos 2 0.08 Source: WDFW (2004) The threshold sediment grain size was evaluated along the proposed channel based on hydraulic conditions provided by the HEC-RAS model and a slope based relationship for the grain mobility reference shear stress. See Appendix C for a technical explanation regarding reference shear stress. Chart 1 shows the modeled channel bed shear stress for each cross- section for the 1-year recurrence interval discharge and the corresponding threshold grain size. . . . . ·-'' .. . . Q = 48 els (i.36 ems), kvea r RI <> ·n,reshOld Gr;aln Size =~=~~-'--'-'-'i--'-1--'-----'-"-''-'----'---'-'--~,-'-'l -· ·-Ch"annE!I shear· stress . 2+00 4:+-00 . . .. . Ref~ref)C~~hearstreil'iS:b_a~ed o_n EG_L'.~ktpe. Notes: Q = discharge flow RI = recurrence interval Chart 1 Threshold Grain Size (48 cfs) 95% Draf/: Design and Constructa.bility Report Upper Springbrook Creek Project 6+00 : River.Station (ft) 7 March2010 090202-01 Design Analysis Chart 2 shows the model channel bed shear stress for each cross-section for the 10-year recurrence interval discharge and the corresponding threshold grain size. 1.0 · 0.5 : 0.0 . _0+00 .. 1b+OO . . : . . ., : .::;· . Referen;~f:ie(!rs'ires~/S'bCJSE!d_on E_G~_!flhP~'.;:'i ·· Chart 2 Threshold Grain Size {88 cfs) Chart 3 shows the model channel bed shear stress for each cross-section for the 100-year recurrence interval discharge and the corresponding threshold grain size. 95% Draft Design and Construct11bility Report Upper Springbrook Creek Project 8 March2010 090202-{)J Design Analysis 4.0 · 35 . o.o Lc;c_"-:..:.....-'-'---c--'--~~--'-'-'-'--'--"--"--"'-'-...__-"-'--,::_~----'"----'--~~'--'~~--e--C.-..-c:..J o.o 0+00 2+00 .·.· 4+00" :12+00 . Ref~r.en~ s~ear:Stre.ss is 'base~ on EGi' s,opel River Station. (ft}. Chart 3 Threshold Grain Size (121 cfs) The proposed atlvert under South 55th Street is located between Stations 10+50 and 11 +00. The downstream end of the new channel will connect to the existing channel near Station 0+76. No imported sediment will be placed downstream of that location. Additionally, no imported sediment will be placed upstream of the extents required to place and protect the culvert. Overall the evaluation of threshold grain sizes shows that for the 1-year discharge a grain size of approximately 2.0 inches would be stable for a majority of the cross-sections. For the 10-year discharge a grain size of approximately 2.5 inches would be stable for a majority of the cross-sections. For the 100-year discharge a grain size of approximately 3.0 inches would be stable for a majority of the cross-sections, with a grain size closer to 4.0 inches required at some cross-sections. Because of differing objectives and constraints in various locations with.in the Project area, imported stream sediment was separated into two different specifications. Type 1 sediment will be placed within the atlvert and along portions of the channel bank where erosion is 95% Draft Design and Const:ructability Report Upper Springbrook Creek Project 9 March2010 090202-01 Design Analysis not desirable. This sedirnent specification is designed to be immobile for discharges up to the 100-year recurrence interval event. Type 2 sediment will be placed along channel banks and bed to a minimum thickness of 1 foot. This sedirnent is designed to be slightly mo bile at the 1-year recurrence interval discharge and moderately mobile at the 10-year recurrence interval discharge. Type 2 sedirnent will serve as spawning substrate for coho and other native fish species. AB the stream evolves and becomes dynamically stable this sedirnent will become sorted as riffles develop a coarser mo bile armor layer and finer fractions are deposited in scour pools and other low shear stress areas of the channel. Table 4 shows the GSD for each sediment specification. Table 5 shows the GSD specification tolerances for construction. Table4 Imported Channel Sediment GSD Type 1 Type2 Culvert Fill, Bank Riffles, Spawning Areas, Use Stabilization Channel Banks, and Bed Median Grain Size, D50 (in) 5 1.3 100% Passing, D10o (in) 24 . 10 84% Passing, D84 (in) 10 3.5 16% Passing, D16 (in) 1.5 0.44 5% Passing, Dos (in) 0.1 0.08 D84/'D,oo 0.4 0.35 D,JDso 2 2.3 D84/'D 16 6 8 Table 5 Imported Channel Sediment GSD Specification Type 1, Culvert Fill Bank Sediment Type Stabilization Standard Sieve Size Percent Passing Range 24in 98-100 12in 85-93 10 in 80-88 Gin 55-63 5 in 45-53 3 in 25-34 95% Draft Design and Consl:Iucmbility Report Upper Springbrook Creek Project JO Type 2, Rlffles, Spawning Areas, Channel Banks and Bed Percent Passing Range 100 100 98-100 95-100 92-98 76-88 March2010 090202-01 Design .Analysis Type 1, Culvert Fill Bank· Type 2, Riffles, Spawning Sediment Type Stabilization Areas, Channel Banks and Bed Standard Sieve Size Percent Passing Range Percent Passing Range 1-1/2 in 10-18 45-55 3/ 4 in 5-10 20-31 7/16in 3-7 12-20 #10 1-3 1-8 #200 0-2 0-2 Relative secliment mobility for the selected import secliment types and the recommended Washington Department of Fish and Wildlife (WDFW) spawning gravel (Table 3) was evaluated at each cross-section in the proposed conditions model. Relative sediment mobility is expressed as the ratio of the channel shear stress to the grain mobility reference shear stress. Relative shear stress values less than 1.0 indicate insignilicant sediment motion (stable sediment). Relative shear stress values greater than 1.0 indicate secliment motion (mobile secliment). Chart 4 shows the relative shear stress condition for a 1-year recurrence interval discharge along with the corresponding channel shear stress. 95% Draft Design and Constructability Report Upper Springbrook Creek Project 11 March2010 090202--01 Reference SheCJr ·stress is bQSit:f aO EGL slope. Q= 48 cfs (1.36 ems); l'year RI . o. }·3.ln., 050 --Oiannel Shear Stress : .. · River Station (ft} X :c Sedimeflt ciasse5 in 1rlches,_. 5" .Ty/Jtd.1; 1.3 n Typ.e 2'. 0.94 • WDFW. Cah~.~ed_ds; Chart 4 Sediment Grain Mobility (48 cfs) X X C X X Design Analysis 3.0 2.0 ;:;-l o.o 12+00 • ~ • • ·~ ~ Chart 5 shows the relative shear stress condition for a 10-year recurrence interval discharge along with the corresponding channel shear stress. 95% Dr;ilt Design and Constructa.bility Report Upper Springbrook Creek Project 12 March2010 090202-01 Design Analysis ·:::::-=::::-:-: _·. ..·. . : · .. : ,. :. . . . . . Q= 8!! cfs(2.49 cms), 10,year RI • 10 . . ..... : Sigf!i.ficaf!t ~e,dl,neni:_motlon --~- g • • . ·.1:1,- ~: • ta -.--·_,:.. · -.. ::-> .... : .. , .. ::-::·::· · ·: i·R·ive~·siit1~.i'"1~1' · Reference sheo;stress ls'bQsed_On EGL slope. . . . . .-" .... :.::.:·: .... ·: ~ed~m~tit Clo$S_e5_1n InChes, 5n Typl? 1{"1.3c~:t):'p_e ~; 0.94"'.WbfW-cOhORedds. Chart 5 Sediment Grain Mobility (88 cfs) The model results indicate that Type 1 sediment (5 inch, Dso) is stable for the modeled cross- sections at the 10-year discharge. The Type 1 sediment was also evaluated to be stable at the 1 OD-year discharge (see Chart 6). The Type 2 sediment (1.3 inch, Dso) is only slightly mobile at the I-year discharge and moderately mobile at the 10-year discharge. This will allow for spawning gravel cleaning and refreshment without losing significant quantities from the restoration reach. The increase in shear stress and turbulence associated with the rootwads on L WD configurations will maintain pools excavated during construction. Cover within ' the pools will also provide valuable hydraulic refuge areas. Chart 6 shows the relative shear stress condition for a 1 OD-year recurrence interval discharge along with the corresponding channel shear stress. Type 2 sediment is clearly mobile at all cross-sections for the 100-year discharge. Type 2 sediment has a maximum relative shear stress of approximately 0.8; safely below the reference shear stress. 95% Draft Design 811d Constructability Report Upper Springbrook Creek Project 13 March2010 090202-01 10 O.l .·o+OO . . .. . "Referen~;ii'e;,~-lsba~dOnEGlioP'~.; . . .. ,. '' Sedime?t Cl~sses In ,Inches, s~Typ_e 1., ~-3_~:rvpe 2, 0.94~ WDFW" Coho~e~d~·.1 Chart 6 Sediment Grain Mobility (120 cfs) Design Analysis 3.0 2.5 2.0 'i, -@. • ~ . • "' o.s 0.0 12+00 For all discharges, the WDFW coho sediment GSD (0.94 inch, Dso) shows slightly higher mobility compared to the Type 2 sediment GSD. This increased mobility is not desirable in the proposed channel because of the unknown upstream sediment supply. The selected Type 2 GSD is still within the acceptable range for spawning gravels. To provide an estimate of the quantity of sediment mobilized through the proposed channel during a typical 1-year recurrence interval discharge event, a sediment transport simulation was conducted. The transport simulation used the empirical transport relations of Parker (1990) and Wilcock and Crowe (2003). These transport relations were developed for use in gravel bed systems and have been shown to be relatively reliable. The U.S. Forest Service's Stream Systems Technology Center BAGS (Bedload Assessment for Gravel-bed Streams) software was used to run the simulations. See Appendix C for additional information regarding the use of BAGS. Additionally, a full explanation of the functionality of BAGS can be found in the BAGS Users Manual (Pitlick 2009). In short, the model used the proposed typical channel cross-section geometry and normal flow assumptions to calculate channel 95% Draft Design and Constmctability Report Upper Spiingbrook Creek Project 14 March20IO 090202-01 Design Analysis shear stress for a specified range of discharges. The specified sediment GSD was then used to calculate the sediment transport stage and corresponding mass transport rate. Chart 7 shows the results of a simulation over a single 1-year recurrence interval discharge event. The measured hydrograph is from the King County stream gage Springbrook Creek 03b (decommissioned) (King County 2010). This measured hydrograph was used to develop the synthetic hydrograph used for the simulation. The synthetic hydrograph has a peak of 48 cfs for 6 hours. -. -· · -... Mea$uie0 Discharge · -.-: .. -. 1 ','.r RI .. Ey~!')t.!hr~sh~l.d ... SiTT1Uiation Timi:! • E , -~- ·t:· _g u .• ~ Empirical tro~sport f'ei~'tions ,~m _wT/co~~ 2003 a~d/a~er -~-9_90 a_re ba_s~ on '!n ass1m.1e_d_ ~urfy~_ GSD"afltJ. n"ormal flc,_w_~nd~ons.: Chart 7 Sediment Transport Simulation The simulation shows that for the synthetic hydrograph and a 1.3 inch surface median grain size sediment (represents Type 2 imported channel sediment) approximately 4 cubic yards ( cy) of sediment may be transported through the system. If the surface grain size is decreased to 1.1 inches the cumulative transport volume may increase to nearly 5 cy. It is more likely, however, that the surface grain size may increase over time. As this occurs the expected transport volume of gravel sediment for a 1-year event is anticipated to dramatically decrease. The simulation shows that if the surface median grain size is 95% Draft Design and Constrorubility Report Upper Springbrook Creek Project 15 March2010 090202-01 Design Analysis increased to 1.5 inches the cumulative transpon volume may decrease to roughly 2.5 cy. This bounded calculation of cumulative sediment transpon indicates that an upstream supply of sediment in the range of 2.5 to 4 cy per I-year event would be sufficient to prevent significant channel degradation. If this sediment supply is not satisfied, degradation may be expected without additional sediment augmentation. Based on the volume of sediment currently present upstream of the existing culven, it appears that a sufficient sediment load is present in the system. 2.3.3 Fish Habitat Evaluation Proposed channel conditions for low flows during the typical coho migration period (October through February) were obtained from the 2001 Hydraulic Repon and used to evaluate recommended spawning and rearing criteria (DEA 2001). The criteria used in this evaluation are summarized in Table 6. Table 6 Spawning and Rearing Criteria Depth (ft) Velocity (ft/s) Description Lower Bound Upper Bound Lower Bound Upper Bound Riffle 0.33 0.82 0.98 1.80 Pool 1.64 4.00 0.30 0.79 Spawning criteria provided by Jackels {2009) Results from the proposed HEC-RAS model within the realigned channel ( downstream of the replacement culven) were compared to the recommended criteria for stream riffles for the two lower discharges. These results are summarized in Table 7 and shown in Chans 8 and 9. Average water depth in the channel during the 3.2 ds flow was approximately 0.6 inches less than the lower bounding criteria for riffles. The water depth was just below the lower bound depth throughout a majority of the proposed channel for this discharge ( Chart 1). Average depths during the 4.5 cfs flow met the lower bound criteria for depth through a majority of the channel with some localized areas that were below the specified depth. 95% Draft Design and Constructability Report Upper Springbrook Creek Project 16 March2010 090202-{)] Design Analysis Table 7 Spawning and Rearing Criteria, Model Summary (1) Flow Discharge Depth (ft) Event (els) Minimum Average Current 3.2 0.23 0.29 Future 4.5 0.25 0.35 See DEA 2001 for explanation of hydrology values. :0.2 ;0.0 Charts Velocity (ft/s) Maximum Average 1.76 1.59 2.65 1.81 ·~;..--~.Lovier Bound Criteria :-:*~-45 cfs ;::-~-i. 3.2 cfs Water Depth in Proposed Channel at Low Flows (3.2 cfs and 4.5 tfs) 95% Draft Design and Const:ructBbility Report Upper Springbrook Creek Project 17 March2010 090202-01 3.0 2.5 Chart 9 Design Analysis .. -· ·-· -· _Uppei' BoUiid Criteria ----· Lower Bound Criteria·:,: :· · ~---·4.5 cfs · ~ 3.2cfs Velocities in Proposed Channel at Low Flows (3.2 cfs and 4.5 cfs) Cross-section averaged channel velocities for both flows were higher than the lower bound criteria; however, average velocities are within the range of recommended velocities throughout a majority of the proposed channel (Chart 2). The cross-section averaged channel velocities for the 3.2 cfs flow remain below the upper bound value. Just downstream of the proposed culvert, and at five cross-section locations near the downstream end of the proposed channel where it appears the water depth is more shallow, velocities are slightly higher than the upper bound criteria for velocities for the 4.5 cfs modeled discharge. It is important to note that these results are for the relatively plain trapezoidal channel configuration without the inclusion of L WD or placed gravel bars. To examine the effect of micro-topography (pools and riffles) on hydraulic conditions for fish habitat, a second, more detailed HEC-RAS model was developed. This habitat model was developed to include the placement of L WD, scour pools, and gravel bars. The model examines a section of the stream that is representative of the proposed L WD configurations. The area obstructed by L WD configurations and the proposed initial pool extents were incorporated into the model geometry. The cross-section geometry and L WD configurations are roughly shown on Plan Sheets 10 and 11: Modeled discharges included the existing and future conditions low flow as well as a typical high flow (10 cfs) in the fish migration period. 95% Draft Design and Constmctability Report Upper Springbrook Creek Project 18 March2010 090202-01 Design Analysis The high flow value represents a typical high flow during the period between October and November based on 5 years of gage data (King County 2010). Charts 10 through 12 show the relevant output from the habitat model with respect to the model station. For L WD location comparison purposes the model station is approximately 76 feet greater than the proposed channel alignment station. Each chart shows and labels the upper and lower bound criteria values for pool velocity and. depth, respectively; 28. Chart 10 Habitat Model Results (3.2 cfs) 95% Draft Design and Constructa.bility Report Upper Springbrook Creek Project H_Ec-RAs s~Ori ·(ft) 19 March2010 090202-01 Design Analysis 3.0 2.5 : 43 g. C 0 " • 38 > • !ii ---W.S.Elev --0.5·. 0 . : AVg. veiodt'( L2,__,_~~'-'-'--'-''--'-'-'-~~......:..2¢z::::===;::;::z.:::.:::.::::.:::.:::=;±=~ -1.0 28 5+00 s~o: Chart 11 Habitat Model Results (4.5 ds) . 5+00 .5+20 5+40 . 5+60 5+80 Chart 12 Habitat Model Results (10 ds) 95% Dndt Design and Construct:2.biEty Report Upper Springbrook Creek Project HEC·~,5 strtion. (ttJ 20 ~+sq : · ·1+00 3.0 0 0 J : I \o ·/ : I! ?,' I .. i 0 , \ /0 ! . i I ·o . Avg. V:eloclty 6+80 -1.0 . '7+00 March2010 090202-01 Design Analysis Table 8 summarizes the habitat model results relevant to the coho spawning and rearing criteria. Results are averages over the extent of the habitat model for the specific channel feature type (riffle or pool). The model shows that spawning and rearing criteria are satisfied for a discharge of 3.2 cfs in both the pools and riffles. For a discharge of 10 cfs the model shows that depth criteria are satisfied but the velocity criteria are slightly exceeded on average. Table 8 Spawning and Rearing Criteria, Model Summary (2) Depth (ft) Velocity (ft/s) Description 3.2 ds 10ds 3.2 cfs 10ds Riffles 0.3 0.7 2.0 2.4 Pools 1.7 2.0 0.79 1.5 Although the habitat model captures the basic geometry of the L WD configurations and pools, inherent limitations of the one-dimensional model do not capture complex variations in velocity around L WD and in pools. Therefore, it is likely that there will be areas that satisfy the velocity criteria at a discharge of 10 cfs. 2.4 Proposed In-Channel Large Woody Debris Placement Placement of L WD in the proposed channel includes three configurations: a channel center log configuration (Type 1), a bank log configuration (Type 2), and a bend stabilization log configuration (Type 3). In-channel L WD placement locations are shown on Plan Sheets 5 through 7 and details are shown on Plan Sheets 10 and 11. L WD have been placed throughout the channel such that it encourages a natural pool and riffle spacing while exceeding the key piece requirements for the 75th percentile of key pieces in natural systems according to recommendations by Fox and Bolton (2007). The proposed L WD placements are a vital component in the maintenance of fish habitat. The logs will increase hydraulic variability, promote accumulation of other debris, and enhance fish habitat by providing holding areas with cover and refuge, aeration of surface water, and localized scour and deposition of channel material (micro-topography). The Type 3 placement will also aid in the stabilization of the outer right bank bends and minimize the potential for lateral channel 95% Draft Design and Constructability Report Upper Springbrook Creek Project 21 March2010 090202-01 Design Analysis migration to the north. In addition, the hydraulic roughness provided by the rootwads will dissipate hydraulic energy that may otherwise cause erosion of the banks. 2.4.1 LWD Log Quantities and Locations The proposed quantity of in-channel L WD is based on reco=endations for wood loading of key pieces to the 75th percentile of natural conditions according to criteria established by Fox and Bolton (2007). Over time, it is expected that additional L WD (smaller pieces in particular) will accumulate within the channel contributed from upstream or from the surrounding riparian vegetation as the result of natural mortality, windfall, and other causes, leading to a total L WD quantity of large and small pieces similar to natural systems. Table 9 su=arizes the reco=ended quantities of L WD and key pieces for a 0-to 6-meter bankfull width (BFW) channel in the Western Washington region. Key pieces are defined as having an adequate size such that the wood is stable and functional with the ability to retain other pieces of organic debris. While the typical individual log volume proposed is slightly less than the value reco=ended by Fox and Bolton (2007), the L WD will be stabilized with mechanical soil anchors and partially buried in the bank. Therefore, the proposed logs will remain stable and function to accumulate additional wood over time. Table 9 Recommended Natural Conditions LWD Quantities L WD Pieces per 100 meters Key Pieces per 100 meters BFW(meter) 75th Percentile Median 25th Percentile 75th Percentile Median 25th Percentile 0-6 > 38 29 < 26 > 11 6 <4 Fox and Bolton (2007) The proposed channel alignment downstream of the South 55th Street culvert crossing is approximately 975 feet long, or 297 meters. For the purposes of this assessment it is assumed that the channel is 300 meters long. As summarized in Table 10, the design proposes approximately 13 pieces of in-channel L WD for every 100 _meters throughout the new alignment when all individual log placements with rootwads are included, which exceeds the reco=ended 75th percentile guideline of 11 key pieces presented by Fox and Bolton (2007). The quantity for every 100 meters becomes approximately 22 pieces when all logs, including those within multiple-log formations, are totaled. 95% Draft Design and Constructability Report Upper Springbrook Creek Project 22 March2010 090202-01 Design Analysis Table 10 Proposed LWD Quantities and Volumes Average Pieces per Total Pieces Design Element 100 meters Proposed Individual Log Placements 13 40 Pieces with 5 16 Multiple Log Rootwads Structures All pieces including 9 27 stringer I ogs ' Total LWD placements 22 67 The proposed locations for in-channel L WD were developed in an effort to maximize habitat complexity by encouraging the formation of natural stream features. The placement spacing is intended to provide an even distribution of pool and riffle features along the proposed channel. Project stations and channel positions for the L WD configurations are listed in Plan Sheets 12 and 13. 2.4.2 In-Channel LWD Placement Types Type 1 log configurations will be placed in straight portions of the proposed channel with the rootwad facing upstream. The configuration will provide hydraulic variability along the length of the corresponding riffle. These logs will be partially buried in the gravel substrate and a pool will be excavated around the rootwad. The pool is intended to provide increased flow depths at low flow simulating natural conditions. The pool is anticipated to be naturally maintained by the turbulence caused by the rootwad placement. Type 2 log configurations will be placed on alternating channel banks. The configuration will encourage alternating pool, bar, and riffle features. During placement of the Type 2 logs a pool will be excavated around the rootwad to a minimum depth of 1.0 feet below the rootwad The pool will be lined with imported channel sediment, Type 2. The pool is anticipated to be naturally maintained by the turbulence induced by the rootwad placement. Between the alternating bank placements, riffles are likely to form. Placement in series along the outside of meanders will tend to decrease bank erosion by deflecting the high energy current away from the bank. 95% Draft Design and Constmct11bility Report Upper Springbrook Creek Project 23 March2010 090202-01 Design Analysis Type 3 configurations will be placed on the right bank (north side) of selected meanders. This configuration will provide pool habitat and minimize the potential for lateral migration of the proposed channel to the north. These placements will be accompanied by placement of Type 1 imported channel sediments. The Type 3 L WD configurations will be bedded into the imported sediment and partially covered as shown on Plan Sheet 11. This coarser sediment will provide additional protection against bank erosion and lateral channel migration. During placement of the Type 3 configurations a pool will be excavated around the rootwads to a minimum depth of 1.0 feet below the rootwads. The pool is anticipated to be naturally maintained by the turbulence induced by the rootwad placement. 2.4.3 L WD Stability and Expected Scour Mechanical soil anchors will be used to secure the L WD configurations in place. Details and specifications for the soil anchors and their connection to the L WD configurations are shown on Plan Sheets 10 and 11. The load capacity of the soil anchor and connections to the log is based on the expected maximum buoyancy and drag forces exerted on an exposed log during a 100-year flow event. The net buoyancy and drag force calculated for an exposed log in the center of the channel during a 100-year event is 500 pounds [2 kilonewtons (kN) ]. All soil anchors will be proof tested to a load of 1,000 pounds, per Project specifications, which provides a stability factor of safety of 2.0. The stability factor of safety provides additional protection against uncertainties such as subsurface conditions, unexpected high flows, and unexpected accumulation of debris, thereby increasing the drag forces exerted on the log placement. All portions of the mechanical soil anchor to L WD connection will have a rated load capacity that exceeds the proof test load. Although a factor of safety has been considered for the mechanical soil anchors and log cabling, this factor of safety does not protect the installation from unexpected scour and undermining of the mechanical soil anchor. Pools excavated during placement of the L WD will be naturally maintained due to the local turbulence inflow caused by each rootwad at higher discharges. Although fine sediments may be deposited in the pools following small flood events it is anticipated that the sediment will then be scoured out during subsequent larger flow events. These deposition and scour 95% Draft Design and Consl:Iud:8bility Report Upper Springbrook Creek Project 24 March2010 090202-01 Design Analysis cycles will help maintain sufficient pool habitat depths especially around L WD rootwads. The proposed pool volume excavation is based on maintaining a similar cross-sectional flow area, below BFW, at L WD placement locations compared to locations without L WD. The depth and extent of the pools was based on professional judgment and experience with similar L WD installations. 2.5 Proposed Floodplain Log Placements and Plantings Log poles will be placed in a linear continuous structure at an approximately east-west orientation along the northern boundary of the Project area in the existing floodplain. Each log pole will be buried to one-half the diameter, as shown on Plan Sheet 25. Offsetting the logs from the channel bank will allow floodplain connectivity to the extent possible (within the Project extents), while retaining flows in the vicinity of the proposed channel. The floodplain log pole structure specified will contain flows within the Project area approximately up to a 10-year event (assuming no leakage between logs of the structure), with a minor amount of flow overtopping the logs at greater flows. Individual logs with rootwads will be placed, angled upstream of the floodplain log pole structure, to provide low velocity refuge areas and additional floodplain roughness, thereby increasing the ability to trap overbank sediments and build up a natural berm over time. The individual rootwad logs do not affect the containment of floodwaters; therefore, the sizing of these logs will likely be dependent upon availability of materials. The individual rootwad logs will be secured in place using a mechanical soil anchor driven into the floodplain subgrade and affixed to the bole behind the rootwad. Size ( diameter and length) specifications for the floodplain log pole structure were determined by modifying and running the proposed hydraulic model in an iterative manner to establish the appropriate height to contain floodwaters at various peak flow events. It should be noted that the calculations performed to estimate log diameters assume a vertical, non-porous structure located at the northern boundary of the Project area. Therefore, small volumes of water that may seep through spaces between the logs are not accounted for in the estimation. However, floodplain plantings of vertical willow stakes are expected to contribute flow retention in addition to the log structure. Additionally, the HEC-RAS model was run as a steady-state condition; the results of the model only simulate the cross-sectional 95% Draft Design and Constructability Report Upper Springbrook Creek Project 25 Mateh2010 090202-01 Design Analysis averaged water surface elevation at the peak of a high flow event, rather than a dynamic scenario such as a multiple day-or hour-long storm event. 2.5.1 Floodplain log Model Development and Analysis To model the floodplain log placements a lateral weir was incorporated into the HEC-RAS model at the Project limit and the flow optimization option was chosen to calculate the amount of flow (cfs) overtopping the weir and leaving the Project area. Because of the low topography north of the site, it was assumed that this flow permanently leaves the site and is unable to re-enter the Upper Springbrook Creek channel. To develop an initial estimate at the height required to retain flows, the crest height of the lateral weir was set to well above the expected water depth at the Project limit. Because this configuration retains all flow in the floodplain, this height is likely an overestimate 8{ flow does not leave the domain. From this initial estimate, the height of the weir was stepped down in 0.05-foot increments until at least 99.5 percent of flow was retained at the 100-, 50-, 25-and 10-year flows. Calculation tolerances of the weir split flow were set to converge to within 0.5 percent of total discharge (the default is 2 percent). Table 11 summarizes the results of the lateral weir split flow sensitivity analysis. Table 11 HEC-RAS Lateral Weir Analysis Summary Flow Event Total Discharge Over Weir Discharge In-Channel Average Height of 100% Discharge (ds) (ds) Weir Above Existing Contained (ds) 10 25 so 100 10 25 50 100 Floodplain Grade (ft) 10--year 88 0.1 1.2 4.6 9.9 87.9 97.8 105.4 111.0 1.14 25-year 99 0.0 0.1 0.8 3.4 88.0 98.9 109.2 117.6 1.20 SO-year 110 0.0 0.0 0.1 0.6 88.0 99.0 109.9 120.4 1.25 100-year 121 0.0 0.0 0.0 0.0 121.0 110.0 99.0 88.0 1.35 Discharge values rounded to nearest one-tenth cfs. The results of the lateral weir sensitivity analysis show that a weir height that contains a 10- year flow event also retains approximately 92 percent of the 100-year flow. Based on these results, as well as discussion with WDFW and the Corps, it is assumed that the minor amount of flow that would leave the site during a 100-year flow event is likely a significant 95% Draft Design and Constiuctability Report Upper Springbrook Creek Project 26 March2010 090202-01 Design Analysis improvement upon current flooding conditions. Therefore, floodplain logs poles were specified to contain the 10-year peak flow discharge (while allowing for some leakage between log poles). 2.5.2 Floodplain Log Size Specification A log diameter was calculated for a half-buried log using the water depth at the Project limit at each HEC-RAS cross-section where bank overtopping occurred. The calculated diameter was rounded up to the nearest typical log diameter (e.g., 12-inch, 18-inch, 24-inch, and 30- inch). In order to simplify the floodplain log pole specifications, average log length was assumed to be approximately 35 feet with a 5-foot overlap on each side, and the calculated log diameters (to the nearest typical size) were grouped with the output from adjacent cross- sections to determine the minimum log diameter necessary at that location. The typical log diameters determined at each cross-section were broken up into groups of at least two logs (approximately 50 feet in length) to simplify specifications and construction actions. Boodplain log pole specification calculations are presented in Appendix B. The specified diameters shown in Plan Sheets 12 and 13 were placed in the floodplain by super-imposing the geo-referenced HEC-RAS cross-sections on a base map of the site. Z.6 Proposed Culvert Replacement 2.6.1 Culvert Specifications The existing 30-inch-diameter corrugated steel culvert (Existing Culvert 3) at the east end of the Project area will be removed and a new culvert installed. The existing culvert conveys Upper Springbrook Creek under South 55th Street into the channel segment to be realigned as. part of the Project. The replacement culvert will be installed along a similar alignment as the existing culvert. Culvert details are shown on Plan Sheets 18 through 22. Design of the replacement culvert was based on the stream simulation design option methods from the WDFW Design of Road Culverts for Fish Passage (Culvert Design Manual; WDFW 2003) and criteria from the King County Surface Water Design Manual (SWDM; King County 2005). Additional design criteria was also developed based on site-specific limitations including physical constraints and expected fish passage requirements in the new culvert. Physical limitations include the existing channel grade on the upstream end of the 95% Draft Design and Canstructability Report Upper Springbrook Creek Project 27 March2010 090202-01 Design Analysis culvert, the presence of underground utilities (sewer mains and structures), and the design grade of the proposed channel realignment at the downstream end of the culvert. Providing improved hydraulic conditions for fish passage was a primary goal of culvert replacement. The existing culvert presents a considerable fish passage barrier because its downstream invert is perched approximately 3 feet above the channel bed elevation. The design of the new culvert focused on providing appropriate hydraulic conditions for fish passage over a range of stream flows within the physical constraints of the site. These fish passage conditions were achieved using the methods given in the stream simulation design option (WDFW 2003, Chapter 6). The design flows used for culvert design and analysis are as follows: • Fish passage design flow of 3.2 cfs to 4.5 cfs, the 10 percent exceedance flow (Table 1) • Conveyance design flow of 121 cfs, the 100-year return period flow (Table 1) Required conveyance through culverts for the 100-year flood event is regulated by the SWDM (King County 2005, Section 4.3.1.1) and is based on a maximum rise in headwater of 1.5 times the culvert rise. Based on the above described design criteria and the presence of the sewer line within the roadway prism, a 10-foot-span, 4-foot-rise concrete box culvert was selected as the replacement culvert. The alignment, longitudinal profile, and cross-section of the proposed culvert are shown on Plan Sheets 18 through 22. Culvert specifications including vertical alignment, counter sink depth, length, and clearance over the sewer line are shown in Table 12. 95% Draft Design and Constructability Report Upper Springbrook Creek Project 28 March2010 090202-{)J Design Analysis Table 12 Replacement Culvert Specifications Description Culvert Width, Inside (ft) 10.0 Rise, Inside (ft) 4.0 Upstream Invert (ft) 40.58 Downstream Invert (ft) 39.74 Depth of Gravel Fill, Average (in) 14.5 Length (ft) 46 Longitudinal Slope (ft/ft) 0.0182 Clearance Over Sewer (ft) 0.5 The proposed culvert slope of 1.82 percent meets the slope ratio requirements (WDFW 2003, Chapter 6) that the culvert's slope be less than or equal to 1.25 times the slope of the channel upstream of the culvert. For this culvert the upstream channel slope is approximately 4.0 percent. lfthe existing channel slope downstream of the culvert is used (1.6 percent) the slope ratio is 1.14, also within the limit. The proposed 10-foot culvert span meets the culvert width requirements stated in the Culvert Design Manual (WDFW 2003, Chapter 6) that the culvert's width be greater than or equal to 1.2 times the existing downstream BFW plus 2 feet. The existing downstream BFW is 6.7 feet, making the required culvert width 10.0 feet. The culvert counter sink (average depth of gravel fill) depth of 14.5 inches meets the culvert fill requirements (WDFW 2003, Chapter 6) of 30 percent to 50 percent of the culvert rise. The culvert will be filled with Type 1 imported channel sediment. The sediment specification conforms to the design methods in the Culvert Design Manual (WDFW 2003) for stream simulation. The sediment provides a stable bed capable of transporting sediment delivered from the upstream reach through the culvert. A low flow channel will be provided by alternating the locations of larger rock clusters along the culvert sides. Additionally, one large rock sill and two log sills will provide grade control and encourage the development of small pools within the culvert at low flow. The placement plan for sediment in the culvert is shown on Plan Sheet 22. The plan shows locations of the rock and log sills, rock clusters, the low flow channel alignment, and anticipated small pools. 95% Draft Design and CoJJStrocw.bility Report Upper Springbrook Creek Project 29 March2010 090202-01 Design Analysis This culvert configuration will provide flood conveyance up to the 100-year flow without exceeding the SWDM headwater rise criteria of 1.5 times the culvert rise. The culvert will have an interior free board of approximately 0.3 feet during the 100-year flow with no appreciable headwater rise. 2.6.2 Inlet/Outlet Design and Specifications Wingwalls, headwalls, and other stabilization measures at the ends of the new culvert will direct flow through the culvert while stabilizing the road prism and channel banks near the · culvert. Plan Sheets 20 and 21 show proposed wingwalls and headwalls at the ends of the culvert within the road right-of-way. Wingwalls and headwalls will be precast concrete sections joined to the culvert with manufacturer recommended methods. At the outlet of the culvert the ends of the wingwalls will be blended into the channel banks using select placement of larger rocks derived from Type 1 imported channel sediment. Additionally, the stream bed immediately downstream of the culvert will be lined with Type 1 imported channel sediment to provide erosion protection and a natural transition out of the culvert. Plan Sheet 22 shows the extents and details of Type 1 imported channel sediment in and around the culvert. 2.6.3 Fish Passage Evaluation As described in the Culvert Design Manual (WDFW 2003), fish passage criteria for construction of new culverts includes maximum velocities, minimum water depths, and maximum hydraulic drop depths in the fishway, as shown in Table 13. Critical species present in Upper Springbrook Creek include coho salmon; therefore, the fish passage criteria for adult Chinook, coho, sockeye, or steelhead from Table 5-1 in the Culvert Design Manual were used in the analysis. These criteria are valid for culverts between 10 feet and 60 feet long. 95% Draft Design and Constructa.bility Report Upper Spnngbrook Creek Project 30 March2010 090202-01 Design Analysis Table13 Culvert Adult Fish Passage Design Criteria Description Design Criteria Maximum Velocity 6.0 ft/s Minimum Water Depth 1.0 ft Maximum Hydraulic Drop 1.0 ft To verify that the proposed culvert will meet fish passage criteria, a detailed HEC-RAS model geometry of the culvert bed including low flow channel and roughness elements was developed. The culvert was analyzed for fish passage by comparing the results of the model to acceptable values for fish passage criteria (Y{r)FW 2003). Table 14 shows the HEC-RAS model results relevant to the adult fish passage design criteria. Table 14 Proposed Culvert Model Results Maximum Discharge Velocity Maximum Description (cfs) (lt/s) Depth {It) WDFW Passage Criteria N/A 6.0 1.0 Lower Bound Low Flow 3.2 1.9 0.6 Upper Bound Low Flow 4.5 2.2 0.7 1-year Recurrence Interval 48 4.5 1.8 10-year Recurre.nce Interval 88 5.5 2.3 100-year Recurrence Interval 121 6.2 2.7 The results of the detailed culvert model show that for discharges up to nearly the 100-year recurrence interval the culvert meets the hydraulic criteria for adult coho fish passage. Tuvenile fish passage at target flows was assumed to be possible based on the culvert design adherence to the Culvert Design Manual (Y-IDFW 2003) stream simulation approach. This assumption was agreed upon during the Tanuary 2010 Project meeting (Anchor QEA 2010b). 95% Draft Design and Canstmctllbility Report Upper Springbrook Creek Project 31 MErch2010 090202-01 Design Analysis 2.6.4 Road Grade Replacement and Utility Relocation Road grade replacement and utility relocation will be conducted in accordance with all · applicable regulations and design standards. Vertical road alignment will be adjusted as necessary to provide sufficient road thickness over the culvert. The sanitary sewer manhole elevatio.n may need to be adjusted in conjunction with road re-grading. Manhole rim elevation adjustments may be made with riser rings and conform to all applicable regulations and design standards. A telecommunications conduit, owned by Qwest Communications International Inc., may need to be temporarily relocated during culvert placement and replaced in accordance with line owner specifications. Details and specifications for road grade replacement and utility relocation can be found on Plan Sheets 23 and 24, and the specifications package. 95% Draft Design and Constructa.bility Report Upper Springbrook Creek Project 32 March2010 090202-01 3 CONSTRUCTABILITY ANALYSIS Construction of the Project is tentatively scheduled for the sum.mer of 2011, pending Project permit acquisition and contractor selection, among other factors. Potential challenges to the construction of the Project, which may affect the schedule and cost, include: • Unforeseen or unknown utility conflicts during channel excavation and culvert construction • Ingress and egress of vehicular traffic on South 55th Street during construction of the replacement culvert Construction actions and consideration are discussed in the following sections and include: • Recommended construction equipment • Mobilization, site access and staging, and site preparation • New channel construction • In-channel L WD and floodplain log placements • Culvert construction • Creek flow ramping and fish rescue and recovery • Decommissioning of the existing channel • Construction decommissioning and site restqration • Best management practices (BMPs) 3.1 Recommended Construction Equipment The construction site is within an existing wetland and natural drainage area where soils are typically silty and saturated. These conditions limit the type of heavy construction machinery that can be used safely and efficiently. It is recommended that equipment used for the Project include only tracked equipment, as rubber-tired equipment may experience limited traction and maneuverability. The Project site is heavily vegetated in some areas and minimal disturbance to vegetation is desired; therefore, smaller, lighter, and more maneuverable equipment may be the most efficient. Machinery recommended for use in construction of the Project is listed in Table 15. 95% Draft Design and ConstructJJbility Report Upper Springbrook Creek Project 33 March2010 090202-01 Constructability Analysis Table 15 Recommended Construction Equipment Excavation Material LWD Culvert and Fill Transport Placement Construction Tracked Tracked Tracked Excavator or· Preferred Machinery Excavator Dumper Log Loader Backhoe (120-series) (Morooka) Loader Tracked Tracked Tracked Alternate Machinery Excavator Loader Excavator N/A (200-series) 3.2 Mobilization, Site Access and Staging, and Site Preparation Mobilization of the Project site involves the transport and delivery of construction equipment, tools, material, and supplies. Mobilization length of time is dependent upon the contractor's scheduling, availability of equipment/materials/supplies, and the areas available for staging and access. Mobilization also includes the acquisition of any and all construction permits and preparation and implementation of construction plans, such as a Temporary Erosion and Sedimentation Control (TESC) Plan, Care of Water Plan, Traffic Control Plan, Storm water Pollution Prevention Plan and others as necessary. Utility locating is necessary prior to the start of construction activities. Site access is provided at each end of the new channel alignment and two staging areas are . proposed. Disturbance to existing conditions within access and staging areas will be limited to the extent practicable, and the removal and disturbance of riparian vegetation will be limited or avoided to the extent possible. Local and state jurisdictions may require temporary construction easements, and permission to use private property will likely be required for culvert replacement and associated construction actions. Temporary improvements for access and staging areas may be required, such as installation of temporary gravel pads, construction entrances, and other measures. These measures will improve access for equipment in addition to providing erosion and sediment control. Site preparation will involve light clearing and grubbing only as necessary for the movement of equipment along the access and staging areas, and to prepare for excavation of the new channel and other design elements. Less than 1 acre is expected to be disturbed, which 95% Draft Design and Constructahility Report Upper Springbrook Creek Project 34 March2010 090202-01 Constructability Analysis includes the new channel alignment and temporary site access and staging areas. Other site preparation work includes the installation of fish exclusion screens in the existing channel upstream and downstream of the Project site. Site preparation should include identifying potential hazards such as overhead utilities, underground utilities, and areas where shoring protection will be required for construction. TESC measures will be employed during site preparation to limit the amount of erosion on- site, as well as off-site transport of sediment from construction activities. TESC measures proposed include a silt fence along the extent of the Project limits, a temporary rock construction entrance, and potentially temporary gravel pads for access and staging areas. Plan Sheet 8 illustrates the proposed site access, staging, and TESC measures .. 3.3 Demolition Minimal demolition is required for the Project. Demolition includes the removal of the following existing features, which are shown in the Plans: • A derelict culvert headwall located upstream of the existing culvert to be replaced • Asphalt and sub grade removal for replacement culvert and installation of utility casing pipe • An existing culvert under South 55th Street (see Section 3.6, below) • A small sandbag berm located north of the existing channel • A staff gage near the downstream end of the existing culvert to be replaced • Miscellaneous refuse and debris encountered within the Project area (natural debris is not included) • A 4-inch diameter ductile iron water main located immediately upstream of the existing culvert to be replaced; the main has been unofficially identified as abandoned and its removal shall be coordinated with the Utility Owner All demolished materials shall be removed from the Project site and disposed of in an approved disposal site meeting all local, state, and federal regulations. Natural debris (boulders, logs, stumps, etc.) will be dispersed on-site within the floodplain. 95% Draft Design and Constructa.bility Report Upper Springbrook Creek Project 35 March2010 090202-01 Consttuctability Analysis 3.4 New Channel Construction Approximately 970 linear feet of new channel will be created as part of the Project within a 100-foot-wide drainage easement that encompasses a vegetated wetland/floodplain. Excavation of the new channel will require heavy machinery. Table 15 lists recommended and alternate construction equipment. Approximately 1,067 cy of excavation is expected for the construction of the new channel. Of the total excavation volume, 506 c:y is over-excavation of the channel followed by backfill of imported channel sediment (Type 2). Spoils may be used in other design elements, provided the spoils meet standards for those uses. Any remaining spoils will be transported off-site and disposed of in an approved disposal site. It is recommended that construction of the new channel includes the use of two equipment teams; each team consisting of one tracked excavator and one tracked dumper. In an effort to reduce haul distances and minimize impact and disturbance to the Project site, it is recommended that excavation of the new channel occur simultaneously at each end of the new channel and continue toward the middle of the channel. Once excavation of the new channel is completed, one team of equipment may begin construction of the floodplain improvements and another equipment team may begin placing imported channel sediment and in-stream LWD placements from the middle of the proposed channel alignment and continue work towards the downstream end of the Project. Once the floodplain improvements are completed, an equipment team may complete the placement of imported channel sediment and in-stream L WD from the middle of the channel alignment, working towards the upstream end of the Project. Approximately 5 cy of existing material will be left in place at the upstream end of the new channel to minimize the potential of inflow of water from the existing channel. The existing channel will be undisturbed during excavation of the new channel. This upstream material will be removed sequentially when flow is diverted from the existing channel to the new channel as discussed in Section 3. 7. Following construction of the new channel, coir fabric will be installed along the banks of the new channel from the toe of slope, underneath the imported channel sediment, to the 9596 Draft Design 811d Constructability Report Upper Springbrook Creek Project 36 March2010 090202-01 Constructability Analysis top of slope and extend upland of the new channel as necessary to stabilize areas disturbed during construction of the new channel. Coir fabric will be installed in accordance with the manufacturer reco=endations in addition to the Project specifications. 3.5 Large Woody Debris Placements L WD placements are proposed in two areas of the Project area: within the proposed channel and along the northern boundary of the Project area in the floodplain. These areas are discussed in Sections 3.5.1 and 3.5.2. 3.5.1 In-Channel Large Woody Debris Placements The placement of L WD in the proposed channel (in-stream) includes three configurations: two single log placements and a multiple-log bank stabilization structure. Each configuration involves attaching the wire rope to a mechanical soil anchor, driving the anchor(s) below the channel bottom to a design depth, load locking the anchor and proof testing to a specified load, drilling the log(s), and securing the wire rope to the log(s). Placement of the L WD will require the use of machinery (see Table 15 for reco=ended equipment) and installation of the mechanical soil anchors may be performed with light machinery or other means approved by the manufacturer. Type 1 single log configurations involve placement of the log in the middle of the channel with its rootwad facing upstream. A shallow trench will be excavated to place the log with approximately the top one-third diameter of the log above final grade. One mechanical soil anchor, installed into the channel sub grade and affixed to the bole downstream of the rootwad mass, will stabilize the log. During placement of the Type 1 logs a small pool will be excavated around and underneath the rootwad. The pool will be lined with imported channel sediment, Type 'i.. Plan Sheet 10 shows the configuration of this L WD placement. Type 2 single log configurations will be placed on alternating channel banks. The log bole will be buried into the bank a minimum of 2/3 its len~ with the top of the log flush with the top of the bank. One mechanical soil anchor, installed into the bank subgrade and affixed to the bole behind the rootwad mass, will stabilize the log. During placement of the Type 2 logs a small pool will be excavated around and underneath the rootwad. The pool 95% Draft Design ,md ConstroctJJ.bility Report Upper Springbrook Creek Project 37 March2010 090202-01 Constructability Analysis will be lined with imported channel sediment, Type 2. The excavated sediment will be placed as a bar deposit immediately downstream of the L WD placement. Plan Sheet 10 shows the configuration of this L WD placement. The multiple-log bank stabilization structure is a continuous log structure along the outside bends of the right bank in the new channel Logs with rootwads will be placed perpendicular to flow at the top of the right bank with rootwads protruding into the channel and the pole ends buried into the right bank. Log poles will be placed parallel to the channel between the perpendicular logs. The logs will then be tied together using wire rape to create a continuous structure. As illustrated in Plan Sheet 11, mechanical soil anchors will be installed into the bank subgrade and affixed to the structure minimizing the likelihood of the structure becoming mobilized. During placement of the Type 3 configurations a pool will be excavated around and underneath the rootwads. Topsoil and vegetation removed for placement of the logs into the right bank will be set aside and replaced following backfill of the logs. 3.5.2 Floodplain log Placements Placement of L WD in the floodplain includes construction of a linear, continuous log pole structure and individual rootwad logs. These placements require the use of equipment similar to that required for in-channel placement of L WD (see Table 15). Work required for construction of the floodplain log placements should be completed prior to completion of the new channel construction and prior to revegetation efforts, which are expected to occur under a separate contract following completion of the Project. Revegetation efforts include floodplain plantings (live stakes along the floodplain log pole structure), as well as additional riparian plantings along the new channel and in the floodplain. The floodplain log pole structure will require clearing and grading and a shallow trench excavation to partially bury the log poles to a depth approximately one-half the diameter of each log pole placed. Access for machinery to place the floodplain logs is shown in Plan Sheet 8. All efforts will be made to minimize the amount of disturbance of the floodplain to complete this portion of the Project. Areas disturbed by the use of machinery for the placement of floodplain logs will be temporarily stabilized with the use of straw, coir fabric, 95% Drafi: Design and COIJStructability Report Upper Springbrook Creek Project 38 March2010 090202-01 Constructability Analysis or other measure. Log poles placed in the structure, with the exception at the ends of the structure, will overlap adjacent log poles by approximately 5 feet and the overlapped portion of adjacent logs will require tight-fitting tolerances. The individual rootwad log placements in the floodplain will be located and oriented as shown in Plan Sheets 12 and 13. Placement of the rootwad logs will require minimal clearing and grading to place the rootwad logs on level grade. Each rootwad log will be stabilized with one mechanical soil anchor installed into the floodplain subgrade, similar to the in-stream rootwad log placements. 3.6. Culvert Construction Existing Culvert 3 will be replaced with a concrete box culvert. The replacement culvert and concrete headwalls will be installed as shown on Plan Sheets 18 through 22. Prior to co=encing culvert replacement, creek flow will need to be temporarily routed outside of the replacement culvert footprint and into the existing channel. The creek will be diverted into a flexible high-density polyethylene (HDPE) pipe that is capable of conveying the entire creek flow. In addition to the temporary pipe, temporary revetments will be necessary to isolate creek flow, both upstream and downstream of the replacement culvert, for installation of the replacement culvert. These temporary flow diversions will remain in place as long as is necessary to construct the replacement culvert, which is expected to last less than 1 week. Construction of the replacement culvert and removal of the existing culvert·will be done in a no-flow condition to the extent practicable, referred to below as "in the dry." Sequencing of events for construction of the replacement culvert includes: 1. Co=ence the road cut. The road will be excavated along the replacement culvert alignment to the footprint and elevation suitable to construct the replacement culvert · to its design elevation. Shoring and trench protection will be employed as necessary. 2. · Temporarily relocate any utility lines as necessary following applicable standard practices and specifications for the particular utility. Any modification of existing utilities will require coordination between the Contracting Officer, Contractor, and Utility Owner. 95% Draft Design and Construrubility Report Upper Springbrook Creek Project 39 March2010 090202-01 Constructability Analysis 3. Install a temporary flow bypass. The flow bypass may include temporary bypass pipe installed from upstream of the replacement culvert construction footprint to the existing channel downstream of the replacement culvert construction footprint. The pipe or other bypass method will have sufficient capacity to convey the entire anticipated creek flow without causing significant backwater. 4. Dewatering methods, including pumping, will be required within the replacement culvert footprint. Additional methods will include flow revetments upstream and downstream of the replacement culvert to convey and bypass the creek flow in order to construct the replacement culvert. 5. Demolish, remove, and dispose of the existing culvert. 6. Expose and protect the existing 12-inch diameter polyvinyl chloride (PVC) sanitary sewer main. Install a steel casing pipe over the sewer main. 7. Construct the replacement culvert; dewater culvert footprint as necessary. Install in- culvert channel sediment. 8. Remove the temporary flow bypass to allow creek flow through replacement culvert. 9. Replace any utility lines as necessary following applicable standard practices and specifications for the particular utility. 10. Repair the road cut according to the applicable jurisdictional standards and requirements. 11. Commence flow ramping and fish rescue and recovery. See Section 3.7 below. Construction sequencing for the replacement culvert and temporary flow diversions are shown on Plan Sheet 9. Construction of the replacement culvert will require the use of heavy machinery (fable 15) and will involve the removal of a section of the asphalt roadway, shoulders, and road subgrade above the replacement culvert and a trench to the extent of the steel casing pipe. The removal will affect an area approximately 15 feet wide by 50 feet long and extends the entire width of the roadway. Placement and connection of the culvert headwalls and wingwalls inay require welding and joint grouting per manufacture specifications. Placement and connection of the safety handrails will require joint grouting per standard specifications. 95% Draft Design and Constructability Report Upper Springbrook Creek Project 40 March2010 090202-01 Constructability Analysis Permanent utility relocation is not anticipated,_although it may become necessary depending upon the final design of the culvert and the potential for encountering underground utilities that are unknown or are located differently than shown on the Project survey. Overhead power lines are present within the Project site and will be avoided.· Underground utility locating will be done prior to the start of the culvert replacement. Temporary closure of South 55th Street due to the construction of the replacement culvert will be minimized to the extent possible. Traffic control will be conducted as necessary to limit the interruption of vehicular traffic within the Project site. Approximately 40 cy of Type 1 imported channel sediment will be placed at a depth of 12 inches to 15 inches along the inside of the culvert bottom and immediately downstream of the culvert as shown on Plan Sheet 22. The substrate may be placed using an excavator, by hand or by other means as necessary. Log sills will also be placed within the culvert and may be placed by hand or by other means necessary. Placement of individual large rocks will be directed on-site by the Contracting Officer. 3.7 Creek Flow Ramping and Fish Rescue and Recovery Once the new channel and replacement culvert is completed, transfer of flow from the existing to the new channel will commence. Prior to the release of water into the new channel, temporary fish exclusion screens will be placed upstream of the culvert within the existing channel and downstream of the confluence of the existing and new channels to exclude fish during the ramping process. Flow from the existing creek will be slowly and sequentially diverted to the new channel in an effort to closely monitor water quality conditions, stability of the new channel, and to perform fish rescue and recovery within the existing creek. Flow rates will be increased in small increments by removal of the existing material at the upstream end of the new channel to allow for these efforts to be conducted successfully. It is anticipated that transfer of the entire flow into the new channel may take as long as 8 hours. It is anticipated that flow ramping from the existing channel to the new channel will be sediment-laden. To mitigate turbid flow in the new channel, a temporary shallow trench or pool will be excavated downstream of the confluence of the new and existing channels, where the turbid water will be pumped into the floodplain. This effort is 95% Draft Design and Construct2hility Report Upper Springbrook Creek Project 41 March2010 090202-01 Constructability Analysis expected to last a short time, yet is dependent upon site conditions and perm.it requirements for water quality. Should the creek flow remain turbid for an extended period of time, other measures will be employed to maintain creek flows. 3.8 Decommissioning of the Existing Channel Once flow has been successfully diverted into the new channel, decommissioning of the existing channel may co=ence. Decommissioning the existing channel involves placement of fill at the upstream end of the existing channel to the extent and length shown in Plan Sheet 13. The upstream fill will require the use of heavy machinery (Table 15). Approximately 19 cy of material is proposed for placement of the upstream fill. Coir fabric installation upland of the new channel, including the extent of the upstream fill of the existing channel will provide short-term stabilization, while riparian plantings will provide long-term stabilization once the vegetation becomes established. 3.9 Construction Decommissioning and Site Restoration Construction decommissioning includes demobilization and removal of temporary construction measures. Items requiring decommissioning include removal of a rock construction entrance and gravel pads for site access and staging, maintenance or removal of the silt fence, and removal of tree protection measures. Site restoration within the Project area includes restoring areas disturbed by construction as necessary. Landscape planting, including planting within the existing channel and floodplain plantings associated with the floodplain log placements, is expected to be conducted under a separate contract following construction completion. Areas disturbed by construction include the temporary site access and staging areas, the banks along the new channel, and the fill area( s) placed during decommissioning of the existing channel. Restoration of these areas may include seeding, mulching, or placement of coir fabric. 3.10 Best Management Practices BMPs are guidelines to prevent the introduction of pollutants and minimize the effect of pollutants to surface water. Pollutants include solids, chemicals, and changes in water 95% Draft Design and Constructability Report Upper Springbrook Creek Project 42 March2010 090202-01 Constructability Analysis temperature, among others. For the purpose of this Project, the BMPs outlined in the sections below are recommended for use on-site to prevent spills, minimize erosion, and control sediment transport. 3.10.1 Spill Prevention The potential for spills occurring during the Project may be prevented, minimized, and/or greatly mitigated by using refueling containment systems, petroleum alternatives in machinery hydraulics, and careful attention paid by operators and staff working in or nearby surface water. BMPs include: • Each piece of machinery shall be checked daily for leaks,· and any repairs shall be done prior to work in or near water. • All refueling of machinery shall be done in the staging areas with appropriate spill containment measures in place and ready to employ. • Fueling procedures must be approved by the local fire department and comply with local and state fire codes, including departments of transportation. • The driver/operator must be present and maintain constap.t observation/monitoring during refueling. • The driver/ operator must be trained in spill prevention, cleanup measures, and emergency procedures. • All employees must be made aware of the significant liability associated with fuel spills. • Spill cleanup materials must be maintained in all fueling vehicles including non-water absorbents capable of absorbing 15 gallons of diesel and conventional fuel. • · Drip pans including absorbent pads will be present at each construction location during all working activities. • If a power generator is used during construction, the generator should be placed out of the creek channel ( above the ordinary high water level) within a spill containment unit. 3.10.2 Erosion and Sediment Control Erosion and sedimentation during construction activities should be minimized by limiting the amount of disturbance to the creek channel, banks, and the top of slope. In order to 95% Draft Design and Constructability Report Upper SpriIJ.gbrook Creek Project 43 March2010 090202-01 Constructability Analysis minimize the potential for erosion and transport of sediment into the creek system, the following actions are reco=ended: • A silt fence installed to the extent shown on the plans to minimize transport of sediment beyond the active construction area. A high-visibility silt fence may aid in marking access routes and clearing limits. • Rock check dams to reduce flow velocity in steep slope drainages and/ or straw bale dams to filter 'sediment in low0 velocity, low-flow drainages. • Clearing limits that are marked_ and visible during construction reduce impacts and disturbance within the Project area. • Rock construction entrance(s) installed to minimize the transport of sediment from the Project area onto street surfaces, and/or equipment washing stations located near surface streets to remove sediment from equipment prior to movement of equipment onto surface streets, and/or use of street sweepers or hand sweeping of surface streets to remove sediment and debris transported off site. • All efforts will be made to locate storage and staging areas in flat areas above the ordinary high water line with appropriate erosion and sediment control measures, such as gravel pads. • The number of trips made through the Project site by heavy equipment will be minimized. • Following construction completion, all disturbed areas that result in bare earth surfaces will be covered with straw or other TESC measure to reduce the potential for erosion and sediment transport. • Excavation requiring the temporary removal of top soil and usable vegetation within the channel should be set aside from other excavation spoils and be used to top-dress bare-cut surfaces following grading work completion. • Revegetation and rehabilitation of disturbed areas is expected to occur following construction completion and will be completed under a separate contract. 95% Draft Design and Constmctability Report Upper Springbrook Creek Project 44 March2010 090202-01 4 LIMITATIONS This report has been developed for the Corps for use in documenting design and constructability analyses for the 95 percent design phase of the Project. Conditions within the Project site may change both spatially and with time, and additional scientific data may become available. Significant changes in site conditions or the available information may require re-evaluation. Within the limitations of scope, schedule, and budget, our services have been executed in accordance with generally accepted scientific and engineering practices in this area at the time this report was prepared. 95% Draft Design 1111d Constroct:Jlbility Report Upper Springbrook Creek Project 45 March2010 090202-01 5 REFERENCES Anchor QEA. 2010a. 35% Design. and Constructability Report; Green Duwamish River Ecosystem Restoration -Upper Springbrook Creek Project. Prepared for U.S. Army Corps of Engineers, Seattle, Washington. Anchor QEA, LLC. March 2010. Anchor QEA. 2010b. Upper Springbrook Creek Restoration Project-Documenta.tion of Additional Planned Changes to 35% Design. and January 14, 2010 Meeting Notes. Prepared for U.S. Army Corps of Engineers, Seattle, Washington. Anchor QEA, LLC. January 2010. DEA. 2001. Hydraulic Report -State Route 167 Culvert Replacement, Upper Springbrook Creek, MP 23.6, King County. Prepared for Washington State Department of Transportation, Northwest Region, Seattle, Washington. David Evans & Associates, Inc. September 2001. DHA. 2008. Upper Springbrook Creek-Topographic Survey, Contract No. W912DW-05- D-1030, Task Order No. 0044. Additional survey collected November 2009. Prepared for the U.S. Army Corps of Engineers. Duane Hartman & Associates, Inc. July 2008. Fox, M. and Bolton, S. 2007. A Regional and Geomorphic Reference for Quantities and Volumes ofinstream Wood in Unmanaged Forested Basins of Washington Sta.te. North American Journal of Fisheries Management. Vol. 27 pp. 342-359. Jackels, C. 2009. Upper Springbrook Design. Criteria for Coho Spawning and Rearing. Documentation provided by Chemine Jackels, Biologist, U.S. Army Corps of Engineers. December 10, 2009. King County. 2005. King County Surface Water Design. Manual King County, Washington. King County. 2007. King County Road Design. and Construction Standards. King County, Washington. King County. 2010. Springbrook Creek Gage 03b {1988-1994). http://green.kingcounty.gov/wlr/waterres/hydrology/GaugeMetaData.aspx?G_ID~67 King County, Washington. Mueller E. R., Pitlick J., Nelson J. M. 2005. Variation in the reference Shields stress for bed . load transport in gravel-bed streams and rivers. Water Resources Research, 41, 04006 95% Draft Design and COilS/:rUctability Report Upper Springbrook Creek Project 46 March2010 090202--01 References Parker, G. (1990). Surface-based bedload transport relation for gravel rivers. Journal of Hydraulic Research, 28(4), 417-436 Parker, G., Dhamotharan, S., and Stefan, H. 1982a. Model experiments on mobile, paved gravel bed streams. Water Resources Research, 18(5), 1395-1408. Parker, G., and Klingeman, P. C. 1982b. On why gravel bed streams are paved Water Resources Research, 18, 1409-1423. Pitlick, John; Cui, Yantao; Wilcock, Peter. 2009. Manwu for computing bed load transport using BAGS (Bedload Assessment for Gravel-bed Streams) Software. Gen. Tech. Rep. RMRS-GTR-223. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 45 p. USACE. 2008. HEC-RAS River Analysis System. Version 4.0.0. U.S. Army Corps of Engineers. March 2008. USACE. 2009. HEC-GeoRAS GJS Toolsfor Support of HEC-RAS Using ArcGJS. Version 4.2. U.S. Army Corps of Engineers. September 2009. WDFW. 2003. Design_ of Road Culverts for Fish Passage. Washington Department of Fish and Wildlife. WDFW. 2004. Stream Habitat Restoration Guide Lines. Washington Department of Fish and Wildlife. Wilcock, P.R., & Crowe, J.C. (2003). Surface-based transport model for nrixed-size sediment. Journal of Hydraulic Engineering, 129(2), 120-128 Wilcock, P. R 1988. Methods for estimating the critical shear stress of individual fractions . in nrixed-size sediment Water Resources Research, 24(7), 1127-1135. 95% Draft Design and Constructability Report Upper Springbrook Creek Project 47 March2010 090202-01 APPENDIX A HEC-RAS PROPOSED HYDRAULIC MODEL RESULTS River Station Profile QTotal Min Ch El (cfs) (ft) 1143.71 1-year 48 45.22 1121.973 1-vear 48 43.86 1115.626 1-year 48 43.04 1103.83 1-year 48 42.5 1099.468 1-year 48 42.3 1058 · Culvert 1056.481 1-year 48 40.78 1047.451 1-year 48 40.74 1029.764 l,year 48 40.42 982.1165 1-year 48 39.56 950 Lat Struct 927.1654 1-year 48 38.56 868.2409 1-year 48 37.48 812.432 1-year 48 36.69 755.3244 1-year 48 35.9 709.8883 1-year 48 35.25 676.08 1-year 48 34.77 655.6738 1-vear 48 34.49 644.5648 1-year 48 34.33 635.4199 1-year 48 34.21 628.682 1-year 48 34.11 617.9985 1-year 48 33.96 594.9594 1-year 48 33.64 576.3321 1-year 48 33.38 560.3003 1-year 48 33.15 547.5794 1-year 48 32.97 534.9249 1-year 48 32.8 522.4411 1-year 48 32.63 507.5188 1-year 48 32.41 487.1755 1-year 48 32.13 469.5943 1-year 48 31.88 433.3106 1-year 48 31.37 95% Draft Design and Constructibility Report Upper Springbrook Creek Project HEC-RAS Proposed Hydraulic Model Results High Flows W.S. Elev CritW.S. E.G. Elev E.G. Slope (ft) (ft) {ft) {ft/ft) 46.29 46.29 46.49 0.027832 45 45 45.37 0.034947 44.54 44.54 45.01 0.027395 43.54 43.54 44 0.034233 43.66 43.17 43.84 0.009322 42.07 42.19 0.006315 41.92 42.16 0.0178 41.6 41.39 41.85 0.017117 40.73 40.55 41 0.018622 39.72 39.63 39.95 0.019124 38.8 38.53 39.01 0.013598 37.86 37.86 38.1 0.019668 36.85 36.72 36.96 0.016819 36.37 36.13 36.43 0.008206 3.6.01 35.81 36.13 0.011009 35.75 35.6 35.89 0.011897 35.61 35.47 35.76 0.011825 35.38 35.33 35.61 0.019064 35.26 35.22 35.48 0.018862 35.17 35.03 35.29 0.011095 34.81 34.68 34.98 0.015739 34.53 34.39 34.69 0.014476 34.28 34.16 34.44 0.015529 34.04 33.94 34.21 0.018297 33.89 33.83 34.02 0.013915 33.76 33.51 33.88 0.012858 33.46 33.46 33.66 0.018945 33.14 33.1 33.3 0.014917 32.81 32.79 32.97 0.018252 32.3 32;24 32.41 0.016062 A-1 Vel Chni Flow Area {ft/s) (sq ft) 3.92 18.68 4.91 9.78 5.6 10.05 5.44 8.83 3.38 14.19 2.79 · 17.23 3.94 12.18 4.04 11.88 4.16 11.54 3.94 15.05 3.63 13.21 4.08 16.13 3.37 25.74 2.59 35.12 3.15 27.08 3.31 23.9 3.33 22.86 4.02 16.56 3.96 18.07 3.13 25.83 3.65 19.62 3.51 21.24 3.56 21.9 3.75 21.59 3.34 26.98 3.26 27.52 3.98 21.93 3.79 27.79 3.85 26.47 3.41 29.67 Top Width (ft) 53.13 13.22 13.44 9.61 10.67 14.69 13.54 12.45 12.39 32.86 13.98 51.04 49.21 61.95 66.17 60.35 59.06 47.1 48.83 51.48 38.61 38.95 45.22 48.2 62.46 64.1 61.69. 93.42 69.93 78.07 Froude # Chi 0.88 1.01 0.89 1 0.52 0.45 0.73 0.73 0.76 0.77 0.66 0.78 0.7 0.5 0.59 0.61 0.61 0.77 0.76 0.59 0.7 0.67 0.69 0.74 0.65 0.63 0.76 0.69 0.75 0.69 March2010 090202-01 River Station Profile QTotal Min Ch El (cfs) (ft) 382.6479 1-year 48 30.66 339.2951 1-year 48 30.06 300.444 1-year 48 29.51 276.5554 . 1-year 48 29.17 252.3564 1-year 48 28.83 219.4787 1-year 48' 28.37 170.3751 1-year 48 27.7 122.1461 1-vear 48 27.01 71.26093 1-year 48 26.13 48.34139 1-year 48 25.71 38.71117 1-year 48 25.54 30.64652 1-vear 48 24.87 20.40138 1-year 48 24.79 8.486752 1-year 48 24.57 1.548412 1-year 48 24.44 1143.71 2-year 70 45.22 1121.973 2-year 70 43.86 1115.626 2-year 70 43.04 1103.83 2-year 70 42.5 1099.468 2-year 70 42.3 1058 Culvert 1056.481 2-year 70 40.78 1047.451 2-year 70 40.74 1029.764 2-year 70 40.42 982.1165 2-year 70 39.56 950 Lat Struct 927.1654 2-year 70 38.56 868.2409 2-year 70 37.48 812.432 2,year 70 36.69 755.3244 2-year 70 35.9 709.8883 2-year 70 35.25 676.08 2-year 70 34.77 95% Draft Design and Constructibility Report Upper Springbrook Creek Project HEC-RAS Proposed Hydraulic Model Results High Flows W.S. Elev CrltW.S. E.G. Elev E.G. Slope (ft) (ft) (ft) (ft/ft) 31.41 31.33 31.52 0.021098 30.77 30.52 30.81 0.011411 30.28 30.16 30.36 0.017542 30 29.78 30.05 0.00987 29.74 29.55 29.8 0.010494 29.13 29.09 29.27 0.030298 28.83 28.31 28.86 0.003589 28.34 28.06 28.54 0.013595 27.45 27.29 27.71 0.019737 26.82 26.77 27.15 0.029242 26.71 26.91 0.015243 26.73 26.81 0.005127 26.66 26.75 0.006622 26.58 26.68 · 0.005154 26.32 26.11 26.6 0.018021 46.41 46.41 46.65 0.028963 45.23 45.23 45.68 0.03332 44.84 44.84 45.38 0.026578 43.86 43.82 44.39 0.02985 44 43.42 44.24 0.00986 42.36 42.53 0.006744 42.2 42.49 0.016221 41.93 41.64 42.22 0.014838 40.88 40.8 41.3 0.025141 39.99 39.85 40.19 0.014495 39.01 38.77 39.3 0.016326 38.03 38.03 38.29 0.019812 37.03 36.85 37.15 0.015835 36.53 36.26 36.61 0.009013 36.19 35.98 36.31 0.010393 A-2 Vel Chnl Flow Area (ft/s) (sq ft) 3.81 27.92 2.35 39.43 3.28 32.77 2.81 42.43 2.82 38.88 4 23.95 1.89 57.69 3.64 13.2 4.1 11.71 4.67 10.28 3.6 13.35 2.31 20.8 2.42 19.87 2.51 19.09 4.24 11.31 4.43 25.52 5.39 12.98 6.2 14.36 5.85 11.96 3.92 17.88 3.24 21.63 4.37 16.01 4.31 16.24 5.17 13.53 3.89 25.8 4.31 16.25 4.42 25.48 3.6 35.13 2.97. 46.16 3.32 39.88 Top Width (ft) 63.57 74.73 85.28 90.82 86.25 69.51 99.89 111.03 13.74 13.36 15.81 17.64 18.76 16.45 11.1 59.83 14.63 15.47 10.34 10.84 15.3 13.95 13.76 13.07 43.97 17.34 57.39 54.26 77.8 73.29 Froude # Chi 0.79 0.56 0.71 0.55 0.56 0.91 0.34 0.66 0.78 0.94 0.69 0.37 0.41 0.41 0.74 0.93 1.01 0.9 0.96 0.54 0.48 0.72 0.7 0.9 0.69 0.74 0.8 0.7 0.55 0.58 March2010 090202-01 River Station Profile QTotal Min Ch El (cfs) (ft) 655.6738 2-year 70 34.49 644.5648 2-year 70 34.33 635.4199 2-year 70 34.21 628.682 2-year 70 34.11 617.9985 2-year 70 33.96 594.9594 2-year 70 33.64 576.3321 2-year 70 33.38 560.3003 2-year 70 33.15 547.5794 2-year 70 32.97 534.9249 2-year 70 32.8 522.4411 2-vear 70 32.63 507.5188 2-year 70 32.41 487.1755 2-year 70 32.13 469.5943 · 2-year 70 31.88 433.3106 2-year 70 31.37 382.6479 2-year 70 30.66 339.2951 2-year 70 30.06 300.444 2-year 70 29.51 276.5554 2-year 70 29.17 252.3564 2-year 70 28.83 219.4787 · 2-year 70 28.37 170.3751 2-year 70 27.7 122.1461 2-year 70 27.01 71.26093 2-year 70 26.13 48.34139 2-year 70 25.71 38.71117 2-year 70 25.54 30.64652 2-year 70 24.87 20.40138 2-year 70 24.79 8.486752 2-year 70 24.57 1.548412 2-year 70 24.44 1143.71 5-year 84 45.22 1121.973 5-year 84 43.86 95% Draft Design and Constructibility Report Upper Springbrook Creek Project HEC-RAS Proposed Hydraulic Model Results High Flows W.S. Elev CritW.S. E.G. Elev E.G. Slope (ft) {ft) (ft) (ft/ft) 35.93 35.8 36.08 0.011752 35.8 35.68 35.95 0.011597 35.56 35.55 35.8 0.018515 35.46 35.41 35.66 0.01697 35.37 35.17 35.49 0.010621 34.99 34.9 35.19 0.01556 34.7 34.58 34.89 0.015177 34.46 34.35 34.63 0.014742 34.17 34.16 34.39 0.021464 34.04 33.94 34.18 0.014362 33.91 33.79 34.04 0.012796 33.58 33.58 33.81 0.020397 33.26 33.24 33.43 0.015414 33 32.93 33.12 0.013716 32.33 32.33 32.53 0.027451 31.55 31.43 31.67 0.020592 30.9 30.6 30.94 0.012099 30.41 30.28 30.5 0.016299 30.13 29.86 30.19 0.009991 29.85 29.69 29.93 0.011387 29.31 29.22 29.44 0.023677 28.91 28.41 28.95 0.005176 28.52 28.31 28.65 0.007461 27.64 27.53 28 0.023218 27.13 27.48 0.022505 27.09 27.29 0.010517 27.1 27.2 0.005233 27.04 27.14 0.005974 26.96 27.08 0.004599 26.69 26.37 27 0.018011 46.47 46.47 46.74 0.029388 45.36 45.36 45.85 0.032481 A-3 Vel Chnl Flow Area (ft/s) (sq ft) 3.54 35.72 3.55 34.49 4.29 26.7 4.1 28.76 3.34. 36.44 4 27.29 3.96 27.93 3.85 30.57 4.36. 28.55 3.7 35.93 3.56 37.36 4.52 30.06 4.18 39.69 3.8 43.93 4.59 32.44 4.22 37.28 2.71 48.87 3.56 44.16 3.13 54.67 3.22 49.17 3.98 40.28 2.4 65.96 2.94' 24.68 4.83 14.51 4.74 14.77 3.55 19.71 2.53 27.63 2.56 27.29 2.75 25.5 4.48 15.63 4.72. 29.34 5.63 14.91 Top Width (ft) 69.6 66.01 59.14 57.03 55.98 41.63 39.46 47.78 55.67 62.89 64.56 68.39 99.41 110.73 82.14 71.51 75.11 90.13 93.59 89.26 100.4 102.16 128.54 15.02 15.36 17.89 19.22 20.46 17.46 12.45 61.3 15.42 Froude II Chi 0.62 0.62 0.77 0.74 0.59 0.71 0.7 0.69 0.82 0.68 0.64 0.81 0.72 0.67 0.91 0.8 0.59 0.71 0.57 0.6 0.83 0.41 0.5 0.87 0.85 0.6 0.37 0.39 0.4 0.7 0.95 1.01 March2010 090202-01 River Station Profile QTotal Minch El (cfs) (ft) 1115.626 5-year 84 43.04 1103.83 5-year 84 42.5 1099.468 5-year 84 42.3 1058 Culvert 1056.481 5-year 84 40.78 1047.451 5-year 84 40.74 1029.764 5-year 84 40.42 982.1165 5-year 84 39.56 950 Lat Struct 927.1654 5-year 84 38.56 868.2409 5-year 84 37.48 812.432 5-year 84 36.69 755.3244 5-year 84 35.9 709.8883 5-year 84 35.25 676.08 5-year 84 34.77 655.6738 5-vear 84 34.49 644.5648 5-year 84 34.33 635.4199 5-year 84 34.21 628.682 5-year 84 34.11 617.9985 5-year 84 33.96 594.9594 5-vear 84 33.64 576.3321 5-vear 84 33.38 560.3003 5-year 84 33.15 547.5794 5-year 84 32.97 534.9249 5-year 84 32.8 522.4411 5-year 83.96 32.63 507.5188 5-year 83.96 32.41 , _ 487.1755 5-year 83.96 32.13 469.5943 5-year 83.96 31.88 433.3106 5-year 83.96 31.37 382.6479 5-year 83.96 30.66 339.2951 5-year 83.96 30.06 95% Draft Design and Constructibility Report Upper Springbrook Creek Project HEC-RAS Proposed Hydraulic Model Results High Flows W.S. Elev CritW.S. E.G. Elev E.G. Slope (ft) (ft) (ft) (ft/ft) 45 45 45.59 0.026055 44.08 43.97 44.62 0.024846 44.21 43.57 44.48 0.010092 42.54 . 42.72 0.006837 42.37 42.69 0.015263 42.13 41.78 42.43 0.013579 40.95 40.94 41.48 0.030044 40.11 39.97 40.32 0.013094 39.12 38.91 39.45 0.017361 38.11 38.11 38.38 0.020296 37.11 36.92 37.25 0.016246 36.62 36.33 36.7 0.009003 36.28 36.11 36.4 0.010155 36.03 35.88 36.18 0.011525 35.88 35.75 36.04 0.01205 35.67 35.63 35.9 0.017637 35.56 35.49 35.77 0.016218 35.47 35.25 35.6 0.01029 35.1 34.97 35.31 0.015381 34.79 34.65 35 0.015719 34.54 34.42 34.73 0.015462 34.24 34.21 34.48 0.021834 34.11 34 34.26 0.014666 33.99 33.85 34.13 0.01314 33.66 33.66 33.9 0.020501 33.37 33.3 33.51 0.012973 32.99 32.99 33.18 0.020698 32.45 32.41 32.54 0.013312 31.62 31.49 31.76 0.02036 30.97 30.65 31.02 0.012442 A-4 Vel Chnl Flow Area (ft/s) (sq ft) 6.49 17.03 5.89 14.33 4.17 20.16 3.45 24.32 4.57 18.39 4.41 19.06 5.81 14.45 3.94 31.45 4.62 21.47 4.63 30.51 3:82 39.95 3.13 52.74 3.44 46.58 3.64 42.66 3.73 40.38 4.36 32.99 4.17 34,82 3.46 42.25 4.18 31.55 4.22 31.54 4.11 34.51 4.59 32.74 3.9 40.84 3.76 42.41 4.76 35.17 4.09 50.29 4.64 42.99 3.5 52.38 4.44 42.92 2.91 54.17 Top Width (ft) 16.6 11.37 11.32 15.66 14.2 14.55 13.37 44.42 71.83 61.08 62.24 78.94 - 73.57 73.04 69.67 62.83 59.77 56.29 41.94 39.73 50.94 55.89 63.12 64.8 71.35 104.6 110.27 118.23 76.07 76.28 Froude # Chi 0.9 0.89 0.55 0.49 0.71 0.68 0.99 0.66 0.77 0.81 0.71 0.55 0.58 0.62 0.63 0.76 0.73 0.59 0.72 0.72 0.71 0.83 0.69 0.66 0.82 0.67 0.82 0.65 0.81 0.6 March2010 090202-01 River Station Profile QTotal Min Ch El {cfs) {ft) 300.444 5-year 83.96 29.51 276.5554 5-year 83.96 29.17 252.3564 s~year 83.96 28.83 219.4787 5-year 83.96 28.37 170.3751 5-year 83.96 27.7 122.1461 5-year 83.96 27.01 71.26093 5-year 83.96 26.13 48.34139 5-year 83.96 · 25.71 38.71117 5-year 83.96 25.54 30.64652 5-year 83.96 24.87 20.40138 5-year 83.96 24.79 8.486752 5-year 83.96 24.57 1.548412 5-year 83.96 24.44 1143.71 10-year 88 45.22 1121.973 10-year 88 43.86 1115.626 10-vear 88 43.04 1103.83 10-year 88 42.5 1099.468 10-year 88 42.3 1058 Culvert 1056.481 10-year 88 40.78 1047.451 10-year 88 40.74 1029.764 10-vear 88 40.42 982.1165 10-year 88 39.56 950 Lat Struct 927.1654 10-year 88 38.56 868.2409 10-year 88 37.48 812.432 10-year 88 36.69 755.3244 10-year 88 35.9 709.8883 10-year 88 35.25 676.08 10-year 88 34.77 655.6738 10-year 88 34.49 644.5648 10-year 88 34.33 95% Draft Design and Constructibility Report Upper Springbrook Creek Project HEC-RAS Proposed Hydraulic Model Results High Flows W.S. Elev CritW.S. E.G; Elev E.G. Slope {ft) (ft) (ft) (ft/ft) 30.48 30.33 30.58 0.015853 30.2 29.97 30.27 0.01008 29.91 29.73 30 0.012171 29.38 29.24 29.5 0.021994 29.04 28.48 29.08 0.004357 28.67 28.4 28.81 0.007123 27.76 28.17 0.024032 27.34 27.67 0.01812 27.31 27.51 0.009415 27.32 27.42 0.005199 27.26 27.37 0.005645 27.18 27.31 0.004485 26.91 26.53 27.23 0.018008 46.49 46.49 46.76 0.029423 45.4 45.4 45.9 0.031841 45.05 45.05 45.64 0.026081 44.14 44.01 44.68 0,023898 44.26 43.61 44.54 0.010154 42.59 42.78 0.006873 42.41 42.74 0.015128 42.17 41.82 42.48 0.013468 40.98 40.98 41.53 0.030599 40.14 39.99 40.35 0.013239 39.15 38.95 39.48 0.017134 38.13 38.13 38.41 0.020973 37.14 36.93 37.27 0.016329 36.64 36.34 36.73 0.009013 36.3 36.14 36.43 0.010167 36.05 35.9 36.2 0.011412 35.91 35.76 36.07 0.012136 A-5 Vel Chnl Flow Area (ft/s) · (sq ft) 3.72 50.75 3.31 61.64 3.48 · 54.49 4.03 47.09 2.38 79.32 3.07 28.25 5.14 16.35 4.61 18.2 3.52 23.83 2.63 31.92 2.63 31.96 2.86 29.4 4.54 18.49 4.79 30.41 5.67 15.52 6.57 17.74 5.92 14.99 4.23 20.79 3.51 25.05 4.63 19.02 4.45 19.75 5.93 14.83 4 32.52 4.64. 23.94 4.73 31.46 3.88 41.39 3.17 54.51 3.48 48.27 3:67 44.5 3.78 42.05 Top Width (ft) 92.84 95.12 90.82 100.9 106.16 133.39 15.81 16.74 18.91 20.15 21.46 18.03 13.32 61.52 15.67 16.89 11.67 11.44 15.76 14.26 14.74 13.49 44.5 73.92 61.75 65.15 79.25 73.64 73.11 70.67 Froude # Chi 0.71 0.58 0.63 0.81 0.39 0.49 0.89 0.78 0.55 0.37 0.38 0.39 0.68 0.95 1 0.91 0.88 0.55 0.49 0.71 0.68 1 0.67 0.76 0.83 0.72 0.55 0.58 0.62 0.64 March2010 090202-01 River Station Profile Q Total Min Ch El (cfs) (ft) 635.4199 10-year 88 34.21 628.682 10-year 88 34.11 617.9985 10-year 88 33.96 594.9594 10-year 88 33.64 576.3321 10-year 88 33.38 560.3003 10-year 88 33.15 547.5794 10-year 88 32.97 534.9249 10-year 87.98 32.8 522.4411 10-vear 87.88 32.63 507.5188 10-year 87.87 32.41 487.1755 10-vear 87.87 32.13 469.5943 10-year 87.87 31.88 433.3106 10-year 87.87 31.37 382.6479 10-year 87.87 30.66 339.2951 10-year 87.87 30.06 300.444 10-year 87.87 29.51 276.5554 10-year 87.87 29.17 252.3564 10-year 87.87 28.83 219.4787 10-year 87.87 28.37 170.3751 10-year 87.87 27.7 122.1461 10-year 87.87 27.01 71.26093 10-year 87.87 26.13 '. 48.34139 10-year 87.87 25.71 38.71117 10-year 87.87 25.54 30.64652 10-year 87.87 24.87 20.40138 10-year 87.87 24.79 8.486752 10-year .87.87 24.57 1.548412 10-year 87.87 24.44 1143.71 25-year 99 45.22 1121.973 25-year 99 43.86 1115.626 25-year 99 43.04 1103.83 25-year 99 42.5 95% Draft Design and Constructibility Report Upper Springbrook Creek Project HEC-RAS Proposed Hydraulic Model Results High Flows W.S. Elev CritW.S. E.G. Elev E.G. Slope {ft) (ft) (ft) (ft/ft) 35.69 35.65 35.93 0.017385 35.59 35.51 35.79 0.01606 35.5 35.27 35.63 0.010207 35.12 34.99 35.34 0.015355 34.82 34.67 35.03 0.015871 34.57 34.44 34.76 0.015654 34.26 34.24 34.5 0.021915 34.14 34.01 34.29 0.014688 34.01 33.88 34.15 0.013059 33.67 33.67 33.92 0.021105 33.39 33.31 33.53 0.012806 33 33 33.2 0.021363 32.47 32.4 32.56 0.013173 31.64 31.5 31.78 0.020311 30.99 30.67 31.04 0.012524 30.5 30.34 30.6 0.015752 30.22 29.98 30.29 0.010106 29.93 29.75 30.02 0.012433 29.4 29.24 29.52 0.021296 29.08 28.5 29.11 0.00417 28.71 28.4 28.85 0.007044 27.8 27.7 28.22 0.024074 27.4 27.73 0.01717 27.37 27.57 0.009205 27.38 27.49 0.005187 27.32 27.43 0.005569 27.24 27.37 0.004503 26.97 26.57 27.29 0.018006 46.54 46.54 46.82 0.029205 45.48 45.48 46.02 0.031625 45.14 45.14 45.79 0.026789 44.29 44.13 44.85 0.021502 A-6 Vel Chnl Flow Area (ft/s) (sq ft) 4.38 34.78 4.19 36.5 3.49 43.84 4.23 32.7 4.29 · 32.49 4.18 35.61 4.65 33.88 3.94 42.22 3.79 43.96 4.87 36.12 4.11 52.56 4.75 44.17 3.53 54.55 .· 4.5 44.46 2.97 55.59 3.77 52.53 3.36 63.51 3.55 55.82 4.02 49.16 2.37 83.1 3.1 29.22 5.2 16.89 4.58 19.18 3.52 24.96 2.65 33.1 2.64 33.24 2.89 30.46 4.56 19.27 4.97 33.38 5.85 16.93 6.86 19.43 5.97 16.91 Top Width (ft) 63.99 60.82 56.38 42.02 40.18 52.13 55.95 63.19 64.87 71.89 105.68 110.84 118.26 77.27 77.44 93.56 95.53 91.21 100.96 107.34 134.57 16.03 17.11 19.18 20.39 21.72 18.18 13.55 62.13 16.21 17.56 12.51 Froude # Chi 0.76 0.73 0.59 0.72 0.73 0.72 0.84 0.69 0.66 0.84 0.67 0.84 0.65 0.81 0.61 0.71 0.58 0.64 0.8 0.38 0.49 0.89 0.76 0.54 0.37 0.38 0.39 0.67 0.96 1.01 0.92 0.84 March2010 090202-01 River Station Profile Q Total Min Ch El {cfs) {ft) 1099.468 25-year 99 42.3 1058 Culvert 1056.481 25-year 99 40.78 1047.451 25-year 99 40.74 1029.764 25-year 99 40.42 982.1165 25-year 99 39.56 950 Lat Struct 927.1654 25-year 98.99 38.56 868.2409 25-year 98.37. 37.48 812.432 25-year 98.37 36.69 755.3244 25-year 98.37 35.9 709.8883 25-year 98.37 35.25 676.08 25-year 98.37 34.77 655.6738 25-year 98.37 34.49 644.5648 25-year 98.37 34.33 635.4199 25-year 98.37 34.21 628.682 25-year 98.37 34.11 617.9985 25-year 98.37 33.96 594.9594 25-year 98.37 33.64 576.3321 25-year 98.37 33.38 560.3003 25-year 98.37 33.15 547.5794 25-year 98.37 32.97 534.9249 25-year 98.19 32.8 522.4411 25-year 97.9 32.63 507.5188 25-year 97.83 32.41 487.1755 25-year 97.83 32.13 469.5943 25-year 97.83 31.88 433.3106 25-year 97.83 31.37 382.6479 25-year 97.83 30.66 339.2951 25-year 97.83 30.06 300.444 25-year 97.83 29.51 276.5554 25-year 97.83 29.17 95% Dra/1: Design and Constructibility Report Upper Springbrook Creek Project HEC-RAS Proposed Hydraulic Model Results High Flows W.S. Elev CritW.S. E.G. Elev E.G. Slope (ft) (ft) (ft) (ft/ft) 44.42 43.71 44.72 0.010207 42.7 42.91 0.007017 42.52 42.88 0.015091 42.28 41.92 42.62 0.013666 41.08 41.08 41.66 0.030037 40.19 40.05 40.42 0.01418 39.24 39.24 39.55 0.01621 38.18 38.18 38.47 0.021502 37.19 36.98 37.34 0.016521 36.69 36.38 36.79 0.009034 36.36 36.18 36.49 0.010188 36.11 35.96 36.26 0.011316 35.97 35.82 36.13 0.012049 35.76 35.7 35.99 0.016798 35.66 35.56 35.86 0.015457 35.57 35.32 35.71 0.010015 35.19 35.05 35.41 0.0152 34.87 34.73 35.11 0.016264 34.62 34.49 34.83 0.016094 34.31 34.28 34.56 0.022259 34.19 34.06 34.35 0.014995 34.06 33.91 34.21 0.013375 33.72 33.72 33.98 0.021075 33.43 33.35 33.58 0.013102 33.04 33.04 33.24 0.021279 32.51 32.4 32.6 0.012891 31.69 31.54 31.84 0.020193 31.03 30.73 31.09 0.01272 30.55 30.37 30.65 0.015509 30.27 30 30.34 0.010173 A-7 Vel Chnl Flow Area (ft/s) (sq ft) 4.39 22.57 3.68 26.93 4.81 20.56 4.63 21.37 6.1 16.23 4.24 34:77 4.64 30.49 4.88 34.74 4.03 45.23 3.28 58.97 3.57 52.51 3.75 48.82 3.87 46.33 4.41 39.36 4.24 40.91 3.57 47.83 4.35 35.62 4.5 34.83 4.38 38.31 4.81 36.64 4.08 45.37 3.94 47.08 5.01 39.6 4.26 56.97 4.87 48.68 3.61 59.8 4.64 48.33 3.12 59.19 3.87 56.99 3.47 68.12 Top Width {ft) 11.79 16 14.42 15.16 13.93 44.67 79.21 64.01 71.32 80.01 73.81 73.29 71.41 66.86 62.88 56.59 42.52 42.36 53.2 56.1 63.34 65.95 73.8 107.74 113 118.33 80.2 80.71 . 95.34 96.53 Frouda # Chi 0.56 0.5 0.71 0.69 1 0.7 0.75 0.84 0.73 0.56 0.59 0.62 0.64 0.75 0.72 0.58 0.73 0.74 0.74 0.85 0.7 0.67 0.84 0.68 0.84 0.65 0.81 0.62 0.71 0.59 March2010 090202-01 River Station Profile QTotal Min Ch El (els) (It) 252.3564 25-year 97.83 28.83 219.4787 25-year 97.83 28.37 170.3751 25-year 97.83 27.7 122.1461 25-year 97.83 27.01 71.26093 25-year 97.83 26.13 48.34139 25-year 97.83 25.71 38.71117 25-year 97.83 25.54 30.64652 25-year 97.83 24.87 20.40138 25-year 97.83 24.79 8.486752 25-year 97.83 24.57 1.548412 25-vear 97.83 24.44 1143.71 SO-year 110 45.22 1121.973 SO-year 110 43.86 1115.626 SO-year 110 43.04 1103.83 SO-year 110 42.S 1099.468 SO-year 110 42.3 1058 Culvert 1056.481 SO-year 110 40.78 1047.451 SO-year 110 40.74 1029.764 SO-year 110 40.42 982_.1165 SO-year 110 39.56 950 Lat Struct 927.1654 SO-year 109.94 38.56 868.2409 SO-year 107.69 37.48 812.432 SO-year 106.66 36.69 755.3244 SO-year 106.46 35.9 709.8883 SO-year 106.46 35.25 676.08 SO-year 106.46 34.77 655.6738 SO-year 106.46 34.49 644.5648 SO-year 106.45 34.33 635.4199 SO-year 106.45 34.21 628.682 SO-year 106.45 34.11 95% Draft Design and Constructibility Reporr Upper Springbrook Creek Project HEC-RAS Proposed Hydraulic Model Results High Flows W.S. Elev Crit W.S. E.G. Elev E.G. Slope (ft) (It) (ft) (It/ft) 29.96 29.78 30.06 0.01316 29.45 29.24 29.57 0.01935 29.16 28.54 29.2 0.003776 28.8 28.4 28.95 0.006898 27.88 27.78 28.33 0.023852 27.54 27.86 0.015159 27.52 27.71 0.008764 27.52 27.63 0.005162 27.47 27.58 0.005405 27.38 27.52 0.004558 27.11 26.67 27.44 0.018003 46.58 46.58 46.88 0.029134 45.57 45.57 46.13 0.031167 45.25 45.25 45.92 0.026582 44.45 44.23 45.01 0.019475 44.57 43.81 44.88 0.010152 42.82 43.04 0.007145 42.62 43.01 0.015103 42.39 42.01 42.74 0.013808 41.18 41.18 41.79 0.029615 40.22 40.1 40.48 0.015672 39.31 39.31 39.61 0.015233 38.22 38.22 38.52 0.021729 37.23 37.02 37.39 0.016597 36.74 36.41 36.83 0.009048 36.4 36.21 36.53 0.010209 36.15 35.98 36.31 0.011346 36.01 35.85 36.18 0.012113 35.82 35.73 36.04 0.016201 35.71 35.58 35.91 0.014801 A-8 Vel Chnl Flow Area (lt/s) (sq ft) 3.74 58.94 3.97 54.68 2.36 92.62 3.19 32.02 5.34 18.33 4.51 21.69 3.52 27.8 2.71 36.07 2.68 36.45 2.96 33.07 4.61 21.23 5.13 36.18 5.99 . 18.36 7.05 21.4 6 18.95 4.51 24.37 3.83 28.74 4.99 22.04 4.79 22.97 6.26 17.58 4.52 · 36.31 4.61 36.23 4.98 37.4 4.13 48.32 3.36 62.33 3.64 55.67 3.83 51.87 3.95 49.25 4.43 42.79 4.25 44.27 Top Width (ft) 92.13 101.12 110.27 136.96 16.61 18.03 19.83 21.01 22.47 18.53 14.1 62.69 16.74 18.42 13.35 12.14 16.24 14.57 17.08 14.34 44.79 81.83 65.8 75.7 80.59 73.94 73.42 71.53 67.61 63.04 Froude # Chi 0.66 0.77 0.37 0.49 0.9 0.72 0.52 0.36 0.37 0.39 0.66 0.96 1.01 0.92 0.81 0.56 0.51 0.72 0.7 1 0.74 0.73 0.85 0.73 0.56 0.59 0.62 0.64 0.74 0.71 March2010 090202-01 River Station Profile QTotal Min Ch El (cfs) (ft) 617.9985 SO-year 106.45 33.96 594.9594 50-year 106.45 33.64 576.3321 SO-year 106.45 33.38 560.3003 SO-year 106.45 33.15 547.5794 50-year . 106.41 32.97 534.9249 50-year 106.04 32.8 522.4411 50-year 105.57 32.63 507.5188 SO-year 105.38 32.41 487.1755 SO-year 105.38 32.13 469.5943 SO-year 105.38 31.88 433.3106 SO-year 105.36 31.37 382.6479 SO-year 105.36 30.66 339.2951 SO-year 105.36 30.06 300.444 SO-year 105.36 29.51 276.5554 SO-year 105.36 29.17 252.3564 SO-year 105.36 28.83 219.4787 SO-year 105.36 28.37 170.3751 SO-year 105.36 27.7 122.1461 SO-year 105.36 27.01 71.26093 SO-year 105.36 26.13 48.34139 SO-year 105.36 25.71 38.71117 SO-year 105.36 25.54 30.64652 SO-year 105.36 24.87 20.40138 SO-year 105.36 24.79 8.486752 SO-year 105.36 24.57 1.548412 SO-year 105.36 24.44 1143.71 100-year 121 45.22 1121.973 100-vear 121 43.86 1115.626 100-year 121 43.04 1103.83 100-year 121 42.5 1099.468 100-year 121 42.3 1058 Culvert 95% Draft Design and Constructibility Report Upper Springbrook Creek Project HEC-RAS Proposed Hydraulic Model Results High Flows W.S. Elev CritW.S. E.G. Elev E.G. Slope (ft) (ft) (ft) (ft/ft) 35.63 35.37 35.76 0.009894 35.24 35.08 35.47 0.015056 34.92 34.77 35.16 0.016565 34.65 34.53 34.88 0.016435 34.35 34.31 34.61 0.022532 34.22 34.08 34.39 0.01517 34.1 33.94 34.25 0.013475 33.75 33.75 34.02 0.021578 33.47 33.38 33.62 0.012986 33.06 33.06 33.27 0.022119 32.54 32.4 32.64 0.012721 31.73 31.57 31.88 0.020127 31.06 30.72 31.13 0.012826 30.58 30.4 30.68 0.015524 30.31 30.03 30.38 0.010228 29.99 29.8 30.09 0.0137 29.5 29.39 29.61 0.018008 29.22 28.59 29.25 0.003648 28.86 28.4 29.02 0.006711 27.95 27.85 28.41 0.023426 27.65 27.96 0.013969 27.62 27.82 0.008511 27.62 27.74 0.005153 27.57 27.69 0.005256 27.48 27.62 0.004607 27.21 26.74 27.55 0.018002 46.62 46.62 46.94 0.030121 45.67 45.65 46.24 0.028936 45.36 45.36 46.05 0.026385 44.6 45.16 0.017973 44.71 43.91 45.04 0.010095 A-9 Vel Chnl Flow Area (ft/s) (sq ft) 3.63 50.81 4.44 37.79 4.65 36.64 4.52 40.33 4.93 38.67 4.18 47.74 · 4.04 · 49.52 5.16 41.73 4.32 60.8 5.03 51.06 3.66 63.58 4.73 51.2 3.22 61.93 3.96 60.03 3.56 71.47 3.88 61.17 3.93 58.91 2.39 98.66 3.25 · 40.18 5.41 19.47 4.47 23.59 3.53 29.89 2.75 38.26 2.72 38.98 3.01 34.98 4.65 22.68 5.36 38.36 6.04 20.04 7.22 23.35 6.04 21 4.63 26.14 Top Width (ft) 56.75 44.28 43.96 53.98 56.21 63.45 67.2 74.97 109.51 114.13 118.38 82.3 83.11 96.53 97.25 92.78 101.25 112.09 137.05 17.06 18.69 20.29 21.44 27.99 18.79 14.5 63.13 17.03 19.27 14.14 12.46 Froude # Chi 0.58 0.73 0.75 0.75 0.86 0.71 0.67 0.86 0.68 0.86 0.65 0.82 0.63 0.71 0.59 0.67 0.75 0.36 0.49 0.89 0.7 0.51 0.36 0.36 0.39 0.65 0.99 0.98 0.93 0.79 0.56 March20IO 090202-01 River Station Profile Q Total Min Ch El (cfs) (ft) ' 1056.481 100-year 121 40.78 1047.451 100-year 121 40.74 1029.764 100-vear 121 40.42 982.1165 100-year 121 39.56 950 Lat Struct 927.1654 100-year 120.72 38.56 868.2409 100-year 116.68 37.48 812.432 100-year 114.13 36.69 755.3244 100-year 113.15 35.9 709.8883 100-year 113.15 35.25 676.08 100-year 113.15 34.77 655.6738 100-year 113.15 34.49 644.5648 100-year 113.01 34.33 635.4199 100-year 112.99 34.21 628.682 100-year 112.99 34.11 617.9985 100-year 112.97 33.96 594.9594 100-year 112.75 33.64 576.3321 100-year 112.75 33.38 560.3003 100-year 112.75 33.15 547.5794 100-year 112.6 32.97 534.9249 100-year 112.06 32.8 522.4411 100-year 111.46 32.63 507.5188 100-year 111.15 32.41 487.1755 100-year 111.15 32.13 469.5943 100-year 111.14 31.88 433.3106 100-year 111.04 31.37 382.6479 100-year 111.04 30.66 339.2951 100-year 111.04 30.06 300.444 100-year 111.04 29.51 276.5554 100-year 111.04 29.17 252.3564 100-year 111.04 28.83 219.4787 100-year 111.04 28.37 95% Draft Design and Constructibility Report Upper Springbrook Creek Project HEC-RAS Proposed Hydraulic Model Results High Flows W.S. Elev CritW.S. E.G. Elev E.G. Slope (ft) (ft) (ft) (ft/ft) 42.92 43.17 0.007277 42.71 43.13 0.015231 42.48 42.11 42.86 0.013887 41.27 41.27 41.91 0.029223 40.27 40.16 40.55 0.016264 39.35 39.35 39.66 0.015462 38.26 38.26 38.56 0.021858 37.27 37.04 37.42 0.016638 36.77 36.44 36.87 0.00906 36.43 36.24 36.57 0.010235 36.18 36.03 36.34 0.011411 36.04 35.89 36.21 0.012191 35.85 35.76 36.08 0.015718 35.75 35.61 35.95 0.014399 35.67 35.39 35.8 0.009845 35.28 35.11 35.52 0.014965 34.95 34.8 35.2 0.016795 34.68 34.56 34.91 0.016697 34.38 34.34 34.64 0.022806 34.25 34.11 34.42 0.015439 34.12 33.96 34.28 0.013851 33.78 33.77 34.05 0.020995 33.41 33.39 33.62 0.018484 33.07 33.07 33.23 0.01841 32.57 32.41 32.66 0.012612 31.75 31.6 ' 31.91 0.020062 31.09 30.74 31.16 0.012939 30.61 30.41 30.71 0.015291 30.33 30.05 30.41 0.010272 30 29.82 30.11 0.014254 29.53 29.4 29.63 0.017151 A-10 Vel Chnl Flow Area (ft/s) (sq ft) 3.97 30.48 5.17 23.41 4.94 24.81 6.4 . 18.9 4.7 38.49 4.73 39.52 5.06 39.79. 4.21 50.91 3.43 65.03 3.71 58.11 3.89 54.24 4.01 51.49 4.44 45.47 4.27 46.84 3.68 53.08 4.52 39.49 4.76 38.03 4.64 41.85 5.02 40.13 4.27 49.34 4.15 50.96 5.19 44.12 5 54.89 4.62 56.35 3.7 66.34 4.8 53.35 3.3 63.92 4 62.63 3.62 73.93 3.99 62.57 3.91 62.03 Top Width (ft) 16.46 14.7 20.51 14.73 44.96 82.19 67.34 79.18 81.04 75.08 73.51 71.63 67.73 63.17 56.87 45.67 45.16 54.57 56.29 63.52 67.93 76.19 106.78 121.23 118.42 83.84 84.81 97.54 97.78 93.18 101.34 Froude # Chi 0.51 0.72 0.7 1 0.75 0.74 0.85 0.74 0.56 0.59 0.63 0.65 0.73 0.7 0.58 0.73 0.76 0.76 0.87 0.72 0.69 0.85 0.81 0.79 0.65 0.82 0.63 0.71 0.6 0.69 0.73 March2010 090202-01 River Station Profile QTotal Min Ch El (cfs) (ft) 170.3751 100-year 111.04 27.7 122.1461 100-year 111.04 27.01 71.26093 100-year 111.04 26.13 48.34139 100-vear 111.04 25.71 38.71117 100-year 111.04 25.54 30.64652 100-year 111.04 24.87 20.40138 100-year 111.04 24.79 8.486752 100-year 111.04 24.57 1.548412 100-year 111.04 24.44 95% Draft Design md Constructibility Report Upper Springbrook Creek Project HEC-RAS Proposed Hydraulic Model Results High Flows W.S. Elev CrltW.S. E.G. Elev E.G. Slope (ft) (ft) (ft) (ft/ft) 29.25 28.61 29.29 0.003599 28.91 28.4 29.06 0.006461 28 27.89 28.47 0.023002 27.72 28.03 0.013218 27.7 27.89 0.008356 27.7 27.82 0.005151 27.65 27.76 0.005157 27.56 27.7 0.00465 27.29 26.79 27.63 0.018028 A-11 Vel Chnl Flow Area (ft/s) (sq ft) 2.42 102.81 3.25 46,36 5.45 20.37 4.44 25 3.53 31.43 2.78 39.88 2.74 41.37 3.05 36.37 4.68 23.75 Top Width (ft) 113.33 137.11 17.4 19.17 20.63 21.76 34.71 18.97 14.78 Froude # Chi 0.36 0.48 0.89 0.69 0.5 0.36 0.36 0.39 0.65 March2010 090202-01 River QTotal Station Profile (cfs) 1143.71 Lower Bound 3.2 1121.973 Lower Bound 3.2 1115.626 Lower Bound 3.2 1103.83 Lower Bound 3.2 1099.468 Lower Bound 3.2 1058 Culvert 1056.481 Lower Bound 3.2 1047.451 Lower Bound 3.2 1029.764 Lower Bound 3.2 982.1165 Lower Bound 3.2 950 Lat 5truct 927.1654 Lower Bound 3.2 868.2409 Lower Bound 3.2 812.432 Lower Bound 3.2 755.3244 Lower Bound 3.2 709.8883 Lower Bound 3.2 676.08 Lower Bound 3.2 655.6738 Lower Bound 3.2 644.5648 Lower Bound 3.2 635.4199 Lower Bound 3.2 628.682 Lower Bound 3.2 617.9985 Lower Bound 3.2 594.9594 Lower Bound 3.2 576.3321 Lower Bound 3.2 560.3003 Lower Bound 3.2 547.5794 Lower Bound 3.2 534.9249 Lower Bound 3.2 522.4411 Lower Bound 3.2 507.5188 Lower Bound 3.2 487.1755 Lower Bound 3.2 95% Draft Design and Constructibility Report Upper Springbrook Creek Project HEC-RAS Proposed Hydraulic Model Results .Low Flows Min Ch El W.S. Elev CritW.S. E.G. Elev E.G. Slope Vel Chnl (ft) (ft) (ft) (ft) (ft/ft) (ft/s) 45.22 45.61 45.61 45.7 0.052441 2.4 43.86 44.15 44.15 44.25 0.051289 2.53 43.04 43.37 43.37 43.48 0.05049 2.73 42.5 42.68 42.68 42.77 0.054022 2.37 42.3 42.61 42.44 42.63 0.004604 1 40.78 41.09 41.1 0.003213 0.83 40.74 41.04 40.98 41.08 0.02423 1.78 40.42 40.65 40.59 40.7 0.020807 1.7 39.56 39.82 39.73 39.86 0.015325 1.56 38.56 38.82 38.76 38.87 0.02109 1.79 37.48 37.77 37.68 37.81 0.015471 1.63 36.69 36.99 36.89 37.03 0.012857 1.54 35.9 36.19 36.1 36.23 0.014896 1.61 35,25 35.53 35.44 35.56 0.014534 1.58 34.77 35.07 34.96 35.11 0.012801 1.53 34.49 34.78 34.69 34.82 0.014358 1.59 34.33 34.63 34.53 34.67 0.013272 1.55 34.21 34.5 34.41 34.54 0.014856 1.61 34.11 34.4 34.31 34.44 0.014224 1.59 33.96 34.25 34.16 34.29 0.01383 1.57 33.64 33.93 33.84 33.97 0.014099 1.58 33.38 33.67 33.58 33.71 0.014753 1.61 33.15 33.44 33.35 33.48 0.014112 1.59 32.97 33.27 33.17 33.31 0.01318 1.55 32.8 33.1 33 33.13 0.013493 1.56 32.63 32.91 32.83 32.96 0.015597 1.64 32.41 32.7 32.61 32.74 0.014215 1.59 32.13 32.42 32.32 32.46 0.014385 1.57 A-12 Flow Area (sq ft) 1.33 1.26 1.17 1.35 3.21 3.84 1.8 1.88 2.05 1.79 1.96 2.08 1.98 2.02 2.09 2.01 2.06 1.99 ·2.01 2.03 2.02 1.99 2.02 2.07 2.05 1.95 2.01 2.04 Top Width (ft) 7.4 6.29 5.05 7.71 10.32 12.65 8.73 8.71 8.51 7.77 7.73 7.82 7.72 7.88 7.79 7.75 7.79 7.74 7.75 7.77 7.75 7.73 7.75 7.79 7.78. 7.7 7.73 8.09 Froude#Chl 1 1 1 1 0.31 0.27 0.69 0.64 0.56 0.66 0.57 0.52 0.56 0.55 0.52 0.55 0.53 0.56 0.55 0.54 0.55 0.56 0.55 0.53 0.54 0.57 0.55 0.55 March2010 090202-01 River QTotal Station Profile (cfs) 469.5943 Lower Bound 3.2 433.3106 Lower Bound 3.2 382.6479 Lower Bound 3.2 339.2951 Lower Bound 3.2 300.444 Lower Bound 3.2 276.5554 Lower Bound 3.2 252.3564 Lower Bound 3.2 219.4787 Lower Bound 3.2 170.3751 Lower Bound 3.2 122.1461 Lower Bound 3.2 71.26093 Lower Bound 3.2 48.34139 Lower Bound 3.2 38.71117 Lower Bound 3.2 30.64652 Lower Bound 3.2 20.40138 Lower Bound 3.2 8.486752 Lower Bound 3.2 1.548412 Lower Bound 3.2 1143.71 Upper Bound 4.5 1121.973 Upper Bound 4.5 1115.626 Upper Bound 4.5 1103.83 Upper Bound 4.5 1099.468 Upper Bound 4.5 1058 Culvert 1056.481 Upper Bound 4.5 1047.451 Upper Bound 4.5 1029.764 Upper Bound 4.5 982.1165 Upper Bound 4.5 950 Lat Struct 927.1654 Upper Bound 4.5 868.2409 Upper Bound 4.5 95% Draft Design and Constructibility Report Upper Springbrook Creek Project HEC-RAS Proposed Hydraulic Model Results Low Flows Min Ch El W.S. Elev CritW.S. E.G. Elev E.G. Slope Vel Chnl (ft) (ft) (ft) (ft) (ft/ft) (ft/s) 31.88 32.19 32.08 32.22 0.011947 1.5 31.37 31.64 31.57 31.69 0.018123 1.72 30.66 30.93 30.84 30.95 0.012048 1.43 30,06 30.36 30.26 30.39 0;013784 1.57 29.51 29.8 29.71 29.84 0.0149 1.61 29.17 29.46 29.37 29.5 0.01331 1.58 28.83 29.11 29.03 29.16 0.015618 1.64 28.37 28.68 28.57 28.72 0.011261 1.47 27.7 27.97 27.9 28.02 0.018922 1.74 27.01 27.33 27.21 27.37 0.010036 1.42 26.13 26.5 26.56 0.028095 1.98 25.71 26.07 25.98 26.1 0.014447 1.54 25.54 25.77 25.77 25.85 0.054337 2.26 24.87 25.53 25.55 0.003893 0.98 24.79 25.43 25.48 0.014142 1.72 24.57 25.28 25.32 0.012074 1.72 24.44 25.17 25 25.23 0.014004 2 45.22 45.66 45.66 45.76 0.052735 2.56 43.86 44.21 44.21 44.33 0.048779 2.77 43.04 43.42 43.42 43.57 0.050231 3.08 42.5 42.72 42.72 42.83 0.052571 2.68 42.3 42.67 42.48 42.69 0.00529 1.18 40.78 41.15 41.17 0.003483 0.97 40.74 41.09 41.15 0.023442 2 40.42 40.7 40.63 40.76 0.020659 1.92 39.56 39.88 39.78 39.93 0.015113 1.76 38.56 38.87 38.8 38.94 0.021552 2.02 37.48 37.83 37.73 37.88 0.015015 1.82 A-13 Flow Area Top Width (sq ft) [ft) 2.13 7.84 1.86 7.64 3.28 18.34 2.04 7.78 1.98 7.74 2.08 8.81 1.95 7.71 2.17 7.87 1.83 7.61 2.26 7.93 1.62 7.5 2.08 8.57 1.41 8.83 3.27 9.83 1.86 6.29 1.86 5.51 1.6 4.03 1.76 8.87 1.63 6.81 1.46 5.14 1.68 7.8 3.8 10.34 4.62 12.78 2.25 8.83 2.34 8.92 2.55 8.76 2.23 8.16 2.48 8.12 Froude ff Chi 0.51 0.61 0.5 0.54 0.56 0.54 0.57 0.49 0.63 0.47 0.75 0.55 1 0.3 0.56 0.52 0.56 1.01 1 1.02 1.02 0.34 0.29 0.7 0.66 0.58 0.68 0.58 March2010 090202-01 River Q Total Station Profile (cfs) 812.432 Upper Bound 4.5 755.3244 Upper Bound 4.5 709.8883 Upper Bound 4.5 676.08 Upper Bound 4.5 655.6738 Upper Bound 4.5 644.5648 Upper Bound 4.5 635.4199 Upper Bound 4.5 628.682 Upper Bound 4.5 617.9985 Upper Bound 4.5 594.9594 Upper Sound 4.5 576.3321 Upper Bound 4.5 560.3003 Upper Bound 4.5 547.5794 Upper Bound 4.5 534.9249 Upper Bound 4.5 522.4411 · Upper Bound 4.5 507.5188 Upper Bound 4.5 487.1755 Upper Bound 4.5 469.5943 Upper Bound 4.5 433.3106 Upper Bound 4.5 382.6479 Upper Bound 4.5 339.2951 Upper Bound 4.5 300.444 Upper Bound 4.5 276.5554 Upper Bound 4.5 252.3564 Upper Bound 4.5 219.4787 Upper Bound 4.5 170.3751 Upper Bound 4.5 122.1461 Upper Bound 4.5 71.26093 Upper Bound 4.5 48.34139 Upper Bound 4.5 38.71117 Upper Bound 4.5 95% Dral/: Design and Constructibility Report Upper Springbrook Creek Project HEC-RAS Proposed Hydraulic Model Results Low Flows Min Ch El W.S. Elev CritW.S. E.G. Elev E.G. Slope Vel Chnl (ft) (ft) (ft) . (ft) (ft/ft) (ft/s) 36.69 37.05 36.94 37.1 0.013285 1.74 35.9 36.25 36.15 36.3 0.01488 1.81 35.25 35.59 35.48 35.64 0.01457 1.79 34.77 35.13 35.01 35.18 0.012856 1.73 34.49 34.85 34.74 34.9 0.014368 1.79 34.33 34.69 34.58 34.74 0.013246 1.74 34.21 34.56 34.46 34.61 0.014699 1.8 34.11 34.47 34.36 34.52 0.013928 1.77 33.96 34.32 34.21 34.37 0.014347 1.79 33.64 34 33.89 34.05 0.013679 1.76 33.38 33.74 33.63 33.79 0.013857 1.77 33.15 33.5 33.4 33.55 0.014737 1.81 32.97 33.33 33.22 33.38 0.013394 1.75 32.8 33.16 33.05 33.21 0.013395 1.75 32.63 32.98 32.88 33.03 0.015512 1.84 32.41 32.76 32.66 32.81 0.014154 1.78 32.13 32.48 32.38 32.53 0.01438 1.76 31.88 32.27 32.13 32.31 0.010833 1.63 31.37 31.68 31.62 31.75 0.023958 2.12 30.66 31 30.88 31.02 0.009383 1.48 30.06 30.39 30.3 30.45 0.01945 1.98 29.51 29.92 29.76 29.96 0.008616 1.51 29.17 29.41 29.41 29.53 0.051152 2.74 28.83 29.18 29.08 29.23 0.015554 1.84 28.37 28.75 28.62 28.79 0.011643 1.67 27.7 28.03 27.95 28.09 0.017962 1.93 27.01 27.4 27.26 27.44 0.010554 1.62 26.13 26.56 26.63 0.026396 2.18 25.71 26.12 26.02 26.17 0.015404 1.77 25.54 25.82 25.82 25.91 0.051785 2.51 A-14 Flow Area Top Width (sq ft) (ft) 2.58 8.19 2.48 8.1 2.51 8.12 2.61 8.18 2.51 8.13 2.58 8.18 2.5 8.12 2.54 8.15 2.51 8.14 2.55 8.16 2.54 8.15 2.49 8.11 2.57 8.17 2.57 8.17 2.45 8.08 2.53 8.12 2.56 8.54 2.76 8.31 2.12 7.84 4.74 23.18 2.27 7.96 2.98 8.48 1.66 7.9 2.45 8.09 2.7 8.26 2.33 7.99 2.78 8.32 2.07 7.88 2.55 8.9 1.79 9.2 Froude # Chi 0.55 0.58 0.57 0.54 0.57 0.55 0.57 0.56 0.57 0.56 0.56 0.57 0.55 0.55 0.59 0.56 0.57 0.5 0.72 0.47 0.65 0.45 1.02 0.59 0.52 0.63 0.49 0.75 0.58 1 March2010 090202-01 River Q Total Station Profile (els) 30.64652 Upper Bound 4.5 20.40138 Upper Bound 4.5 8.486752 Upper Bound 4.5 1.548412 Upper Bound 4.5 95% Draft Design and Constructibility Report Uppet Springbrook Creek Project HEC-RAS Proposed Hydraulic Model Results Low Flows Min Ch El W.S. Elev CritW.S. E.G. Elev E.G. Slope Vel Chnl (ft) (ft) (ft) (ft) (ft/ft) (ft/s) 24.87 25.63 25.65 0.00365 1.04 24.79 25.54 25.58 0.012611 1.72 24.57 25.4 25.44 0.011368 1.71 24.44 25.28 25.09 25.35 0.014011 2.18 A-15 Flow Area Top Width (sq ft) [ft) 4.32 11.31 2.62 8.17 2.64 7.6 2.07 4.57 Froude # Chi 0.3 0.53 0.51 0.57 March2010 090202-01 APPENDIX B FLOODPLAIN LOG PLACEMENT SPECIFICATION CALCULATIONS River· Station Ground Elev. at Pro]. Limit (ft! :'=\ 1143,i'7.l~}'. !%fii'fJN~'f:i'wit'b11~}~;!!271 ~112Un3) ~/i_i::'i1:~A:*1J.':ftil: ..:;i1ts:'621;'._\1 itflJ'ti{N.a;~i;.;;tj:\+: ~i1o3:83ijj ~·~,l{}!N.&.:.fii~Jt ~'11099;·4~_<'; ':tfiflr,1NA'?,;t,f.;c ><·-~-····'" ..... --.. ., 868.2409 52.55 B12 432 48.84 755.3244 36.2 44.19 709.BB83 35.6 27.19 676.08 35.3 21.57 655.6738 35,2 9.98 644.5648 35.2 9.98 635.4199 ,s 10.72 628.682 34.8 11.35 617.9985 34.6 23.31 594.9594 34.1 22.26 576.3321 33.8 18.55 560.3003 33.5 16.42 547.5794 33.2 6.86 534.9249 33.1 4.98 522.4411 '33 11.13 507.5188 32.9 20.46 487.1755 32.8 25.21 469.5943 32.3 24.59 433.3106 31.8 47.37 382.6479 30.9 47.15 339.2951 30 27.92 300.444 29.7 24.Zl 276.5554 29.5 25.02 252.3564 29.3 29.53 219.4787 29 46.7 170.3751 28.S 47.01 122.1461 27.9 31.12 39.15 38.13 37.14 36.64 36,3 36.05 35.91 . 35.69 35.59 35,5 35.12 34.82 34.57 34.27 34.14 34.01 33.67 33.39 33 32,47 31.64 30.99 30.5 30.22 29.93 29.4 29.08 28.71 Floodplaln Los Placement Specification Calculations Aoodplaln leg Speclflw1tlons 0,05 1.2 12 12 53 101 4.1 4 0.43 10.32 12 49 0.94 22,56 24 44 l.D4 24.96 30' 27 1 24 24 " 0.85 20.4 24 0.71 18 18 24 10 158 6.3 6 10 0.69 18 18 11 0.79 18.96 24 11 0.9 21.6 24 23 1.02 24.48 30 " 1.02 24.48 30 19 1.07 25.68 30 1.07 25.68 30 30 16 80 3,2 3 7 1.04 24.96 30 1.01 24.24 30 11 o.n 18.48 24' 20 0.59 14.16 18 25 0.7 16.8 18 18 25 165 6.6 7 0.67 16.08 18 47 0.74 17.76 18 47 0.99 23,76 24 0.8 19.Z 24 24 28 52 2.1 2 24 0.72 17.28 18 0.63 15.12 18 18 25 55 2.2 2 30 M 9.6 12 12 47 47 1.9 2 0.58 13.92 18 0.81 19.44 24' 18 47 78 3.1 3 31 i)·7fasb93}, ft~tU:t-iA%}{{M' ;~~JlWi4)is'f:'HYftf iWi't,h:t.:~~:Ji;, Hf$1P,{t,j}!._~ii','i #JKs#tNl\~4~1~1, :iiJf_)iJ,N,11,t41t11~ ~t;_f;\;!r' p.';,;:;.--:;\ ~:µi~~~·is'.;1tit~1J¥' ~lf~t1ti~A_f~!~[f}: ~74lf@NAJ;:fJ!*.:\fif \~;.'"f.fl;~~i;)iA'~gr:;_th( ::48:34139\•_ M(,~ii:'%\li,["tjtt~ /Jiil1.iif!s:14~"Hf~'fT ifA-%'l'>2;,.;4[g:IJif '/)!fr{{~\_N/\"\.Mf,'if} :J~.lid-11\f,HMf, \{;Jify;:.NA~; i'M~1tr~ :fe:}:{i/,";}'.\.i1~1'.8:f'.~i=i'JW.i?lr.1 i{t~;r,11t,1A'!(i1f,~: 'J<Ri,~Wi:4iNA:~ffil,._nr <0;#1;'(fM(NA_fi~,,1J!,fiA '!"<3a:1fai7,Y_ f :;'1,9:iJ/NA,:Jij.JJ,W· \H!:N!'8'.6_.9lf\WWi':, i W'!-27:;!i!:,liffi'. ,~1.;f<;\(}f,}U,;fi~1f!li 1?1#iit11:NA'.\1~;;l.tf ~lt r:iM@l~ \~NA11.UJ.1!: ~\~,r~a;::lj1Jii\:0l~{~;f0 1t;,:(1~~:!iNAiflf.J,:,S ·i~:/69.rft N),-,JHTifiJ.lfi" \f-fffit11'fi,-1NA~'WtiNi'.'r. 9596 Draft Desip aDd CoDstr:ucribility Reporr Upper SpciDgbrooJ:. Creek Project B-1 Marr:h2010 OSW02--0J River .~412J· Note: HEC·RAS Model Output (10-Year Flow Cont.iined] Rlg:ht OVerbank RHch Lenrth {ft) Floodplaln Log Placement Speclfkation calculations Floodplain Log Speclflcatlons Depth at Grouped Log I Distance Between 1.07 25.68 30.DO •Log diameter to contain now greater than grouped diameter speclflcatlon. This difference does not exceed 1.5 Inches. 9596 Dnft Design RJJd Constructibility Report Upper Springbrook Creel.: Project B-2 March2010 090202-{}J APPENDIX C SEDIMENT TRANSPORT ANALYSIS APPENDIX C Sediment Transport Analysis This appendix provides additional explanation of the sediment mobility and transport evaluations. This appendix is intended to be a primer on basic terminology and relationships and not a comprehensive explanation of sediment transport theory and practice. A majority of sediment mobility and transport evaluations are based on two system parameters. One is the shear stress exerted on the sediment grains by the water. The second is the size of the sediment grains composing the bed. Shear stress on the bed for normal open-channel flow conditions is often approximated by Equation 1. Where p is water density, g is gravitational acceleration, R is the hydraulic radius (flow area over wetted perimeter), and S is the slope of the energy grade line (equal to the bed slope for normal flow). r.=pgRS (1) The bed shear stress can be normalized by sediment grain size and water weight, Equation 2, to produce the dimensionless form of grain shear stress (T'). Where r is bed shear stress, p, is sediment grain density, p is water density, g is gravitational acceleration, and D is grain size. ·r -r*.=--. --- (p, --p)gD The dimensionless form of shear stress can be used to establish a value called the reference shear stress (r,). The value for reference shear stress is defined to produce a small but measurable dimensionless transport rate~' Equation 3) of 0.002 (Parker et. al. 1982a,b;Wilcock 1988). Where Qi is the volumetric sediment transport rate, sis the sediment grain specific gravity, and B is the transport width. W*cc Q,(S'--i)g · ( · .· • )312 · .. . ··. r/p p,B (2) (3) 95% Draft Design and Constmctability Report Upper Springbrook Creek Project C-1 March2010 090202-01 AppendixC This dimensionless transport rate is roughly equivalent to mass sediment transport rate of 1 ounce/feet/second for gravels. The reference dimensionless shear stress ( T!) that produces the specified dimensionless transport rate varies depending on several system parameters and can range between 0.025 and 0.10 with a typical value near 0.04. Recent work has shown that the reference shear stress varies considerably based on the channel slope. Equation 4 is a relationship for this variation in dimensionless reference shear stress with respect to channel slope ( S) as defined by Mueller et. al. (2005). r*, ce2.J8S +0.021 Using the calculated values of dimensionless grain shear stress ( T") and dimensionless reference shear stress (Tl) the transport stage (6) can be defined as shown in Equation 5. (4) (5) The sediment transport stage is used as the primary variable in several common coarse sediment transport models. Depending on the model, the transport stage can be specified for either for the grain size distribution (GSD) as a whole or for individual grain size classes. The two models used to evaluate sediment transport for this project (Parker 1990; Wilcock and Crowe 2003) are capable of modeling individual grain size classes, although only the aggregate transport rate was presented in the report. Both models employ a similar non- linear function for transport rate with respect to transport stage. Explanations of the models basis and functionality can be found in the respective references for each model and many other related publications. The U.S. Forest Service's Stream Systems Technology Center BAGS (Bedload Assessment for Gravel-bed Streams) software was used to run transport rate simulations using both the 95% Draft Design and Constructability Report Upper Springbrook Creek Project C-2 March2010 090202-01 .• Appen<lixC Parker (1990) and Wilcock (2003) models. A full explanation of the functionality of BAGS can be found in the Manual for computing bed load transport using BAGS (Pitlick 2009). Input to the model included information regarding channel cross-section, slope, floodplain boundaries, surface grain size distribution, and water discharge range. An example input data set is shown in Figure 1. Figure 1 Example BAGS Input Data Channel .bed slope Bankfull width N/A .. 0.09cms :3.43 ems Main channel Manning's n • · 0.045 Leftfloodpl~i~ boundary 9.14m . Left floodplain Manning's n • 0.1 Rightfloodplain boundary: . · 13.72 m Right floodplain Manning's n . • .•.. 0.1 .. ' ..... ':: · .. : .. ,., .:· .. '"' .. .. . . .. . '' . Cross-Section Lateral distance (m) Elevation (m) 0 0.4572 9.144 . 0.4572 . • i0.5156 0 12.3444 o· 0.4572. 0.4572 · Surface Grain Size Distribution .•. • Size (rnm) · % Finer 200 100 so••· 84 32 so 10 16 5 5 1 1 • 0.8 0.5 0.5 0 The output provided by the software included data regarding the aggregate bedload transport rate, the transport stage, maximum water depth, hydraulic radius, and the grain size class bedload transport rate. An example output data set is shown in Figure 2. As shown in the report, output data sets were then used to calculate transport rate over synthetic hydrographs and examine system sensitivity to changes in GSD. 95% Draft Design and Constrorubility Report Upper Springbrook Creek Project C-3 March2010 090202-01 Discharge : BediOad transpo~ .. Transport : Maxwater .. {cins! rate {kg/min.) Stage depth {m) 0.090 4.30E-05 0.372 0.089 0.104 . 8.62E-05 0.400 0.097 . 0.120 1.72Ec04 0.431 0.106 . 0.139 . "3.41E-04 0.464 • 0.115 0.161 i6.72E-04 · 0.499 0:125 0.186 ·: 1.28E-03 0.534 0.136 · 0.216 · 2.58E-03 0.576 0.147. 0.250 . 5.05E-03: 0.619 .. 0.160 0.289 9.87E-03 0.665 0.173 0.334 1.83E-02 0.709 · 0.188 0.386 : . 3.48E-02 0.759 0.204 0.447 6.58E-02 0.812 0.221- 0.517 l.24E-01 · 0.867 0.240 0.598 2.27E'01 0.925 0:260 0.691 , 4.13E-01 .0.985 0.281" 0.800 . 7.73E-01 . 1.056 0.303 0.925 -1.34E+OO 1.122 0.327 1.070 , 2.30E+OO 1.194 0.354 1.238 3.87Et00 1.270 0.381 1.432 6.lBE+OO 1.347 . 0.412 . 1.656 9.80E+OO 1.433 0.443 : 1.916 1-62E+Ol · 1,548 0.474 · 2.216 · 2.69E+Ol 1-688 · 0.504 2.563 4:36E+Ol 1.844 0.538 •2.965 6.79E+Ol 2.012 0.574 3.430 1.03E+02 2.198 · 0.614 95% Draft Design and Constructability Report Upper Springbrook Creek Project ,, Figure 2 Example BAGS Output Data Hydraulic sSdi!Tl~.rii:' trilnsport rai:e by size, in .kc/mi~. :· radius (m) ·200·-so mm·· ·so:. 32 mm 3z·.; 10 mm 10-5 mm· 5-1 mm· · 1:.0.Bmm 0.078 2.51E-09 1.31E-06 1.42E-05 l.lOE-05 l.OlE-05 2.72E-06 0. 084 . · ... 5.03E"09 • 2.64E-06 2.84E-05 2.20E-05 2.03E-05 5.46E-06 · 0.091 1.00E-08 5.26E-06 . : 5.66E-05 4.39E-05 4.04E-05 1.09E-05 · · 0. 098• : · • · 1.99E-08 · 1.04E-OS 1.12E.04 8.71E-OS 8.02E-OS 2.16E-OS . 0.105 3.92E-08 • : : 2.06E-05 · · 2.22E-04 • · • 1-72E·04 l.58E-04 · · • 4.26E-05 0.112 -7.45E-08 3.91E-05 . 4.21E-04 3.26E-04 3.00E-04 8.10E'05 0.121 1-50E-07 : . 7.88E-05 8.50E,04 6.59E-04 . 6.06E<04 1.63Es04 0.130 2.95E-07 " · l.55E-04 l.67E-03 1.29E-03 l:19E-03 3.20E'04 o.140 5.76E-07 · • 3.02E-04 3.25E-03 2.52E-03 . 2.32E-03 6.26E-04 0.149 • l.07E-06 5.59E-04 6.03E-03 4.67E-03 4.30E-03 1.16E-03 0.160 2.03E-06 : 1.06E-03 l.lSE-02 8.89E-03 · · 8.lBE-03 2.21E-03 0.171 3.84E-06 • • • 2.0lE-03 · ·2.17E-02" 1.68E-02 " 1.55E-02 · 4.17E-03 • 0.183 · 7.21E-06 3.78E-03 4.08E-02 3.16E-02 2.91E-02 7:84E-03 · 0.195 l.33E-05 6.98E'03 · · ·7.53E-02 · · 5.83E-02 · 5.37E-02 l.42E-02 . • · 0.207•· 2.45E-os· · 1.29E-02 1.39E-01 l.07E-01 · 9.BBE-02 2.42E-02 · 0.222 • 4.74E:05 2.49E-02 2:68E-01 2.08E-01 · 1.82E-01 ·. 4.lOE-02 0.236 · 8.55E'05 4.48E-02 4.83E-01 . 3.73E-01 2.99E-01 6.36E-02 0.251 l.56E'04 8.17E-02 8.80E-01 " · " 6.49E-Ol" 4.77E-01: " "9.65E-02 0.267 ' 2.84E-04. 1.49E-Ol .. : 1.59E+OO 1.08E+OO 7.37E-01 : · 1:43E-Ol 0.283. · : 5.03E-04 2.64E-Ol-• 2.69E+OO l.69E+OO l.09E+OO 2.05E·Ol . 0.302 9.19E'04 4.82E-Ol 4.46E+OO " 2.62E+OO l.61E+OO 2.92E-01 0.326 l.87E-03 • 9.83E-01 • : 7.66E+OO 4.20E+OO 2.45E+OO 4.29E-01 · 0.355 4.08E-03. 2.14E+OO l.30E+Ol. 6.70E+OO 3.71E+OO 6.29E-01 0.388 9.03E-03 4.SOE+OO · • 2.13E+Ol · · ·1.04E+Ol 5.52E+OO • •· • 9.09E-01 0.423 1.98E-02 8.53E+OO · 3.32E+Ol 1.55E+01" 7.97E+OO l.28E+OO 0.463 4.38E-02 1.52E+Ol : 5.04E+Ol 2.28E+Ol l.13E+Ol l.78E+OO C-4 AppendixC 0.8 ;.Q,S rrim 3.67E-06 7.37E-06 •1.47E-05 2,91E-OS · 5:74E-05 1.09E-04 2.20E-04 4.32E-04 8.44E-04. 1.56E-03 .. 2.97E-03 • 5.62E-03 l.05E-02 · 1.83E-02 3.05E-02· . 5.02E-02 7.65E-02 1:14E,Ol 1-67E-01 2.36E:01 . 3.33E-01 4.84E-01- 7.02E-01 1.00E+OO 1.40E+OO 1.93E+OO March2010 090202-01 :