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Home My WebLink AboutAppendix V - Surface Water & WQ DR I-405, Renton Nickel Improvement Project, I-5 to SR 169 SURFACE WATER AND WATER QUALITY DISCIPLINE REPORT October 2005 %&e( !"b$ AÉ !"`$ !"`$ Aæ %&e( Bothell Kirkland Bellevue Renton AÊ AÐ Aí Aô AÌ Aí Aç AÅ Lake Washington Arterial Road Freeway Municipality Lake Park M0 2 Miles I-405 Project Area Renton Nickel Improvement Project SURFACE WATER AND WATER QUALITY DISCIPLINE REPORT I-405, Renton Nickel Improvement Project Prepared for Washington State Department of Transportation Urban Corridors Office And Federal Highway Administration Prepared by Bruce Jensen and Karen Comings, DMJM Harris October 17, 2005 Title VI WSDOT ensures full compliance with Title VI of the Civil Rights Act of 1964 by prohibiting discrimination against any person on the basis of race, color, national origin or sex in the provision of benefits and services resulting from its federally assisted programs and activities. For questions regarding WSDOT's Title VI Program, you may contact the Department's Title VI Coordinator at 360. 705.7098. Americans with Disabilities Act (ADA) Information If you would like copies of this document in an alternate format—large print, Braille, cassette tape, or on computer disk, please call 360.705.7097. Persons who are deaf or hard of hearing, please call the Washington State Telecommunications Relay Service, or Tele-Braille at 7-1-1, Voice 1.800.833.6384, and ask to be connected to 360.705.7097. Renton Nickel Improvement Project Surface Water and Water Quality Discipline Report i R:\04156\33-06 Renton Nickel\Task 3 - Discipline Reports\all reports\Final DRs\Renton Nickel Surface Water & WQ DR_final.doc T ABLE OF C ONTENTS Glossary.............................................................................................................................................................................iii Acronyms and Abbreviations Used in this Report .........................................................................................................v Introduction........................................................................................................................................................................1 What is the Renton Nickel Improvement Project? ...........................................................................................................1 What is the No Build Alternative?................................................................................................................................2 What is the Build Alternative?.....................................................................................................................................2 How will stormwater from the project be managed? .................................................................................................12 What environmental and utilities issues influenced the project design and what was done to avoid and minimize project effects?....................................................................................................................................13 What is planned for wetland and stream mitigation?.....................................................................................................16 What benefits will the project provide?......................................................................................................................17 How will the project incorporate community design preferences?.............................................................................17 How will the project be constructed?.........................................................................................................................18 Why do we consider surface water and water quality for this project? ..........................................................................19 What are the key points of this report?..........................................................................................................................20 Existing Conditions.........................................................................................................................................................21 What information was collected to identify surface waterbodies, existing stormwater facilities, and water quality?......21 What surface waterbodies are present in the study area?.............................................................................................21 Cottage Creek...........................................................................................................................................................23 Gilliam Creek.............................................................................................................................................................23 Unnamed Tributary to Gilliam Creek.........................................................................................................................23 Green River...............................................................................................................................................................23 Springbrook Creek....................................................................................................................................................24 Panther Creek and Wetlands....................................................................................................................................24 Rolling Hills Creek.....................................................................................................................................................24 Unnamed Tributary to Rolling Hills Creek.................................................................................................................25 Thunder Creek..........................................................................................................................................................25 Cedar River...............................................................................................................................................................25 What is the quality of surface waterbodies in the study area?.......................................................................................25 How does urbanization affect surface water?................................................................................................................27 How is stormwater managed in the study area?............................................................................................................28 Stormwater ponds.....................................................................................................................................................29 Biofiltration swales ....................................................................................................................................................29 Ecology embankments..............................................................................................................................................30 Stormwater treatment wetlands.................................................................................................................................30 How do environmental regulations affect the stormwater system design for this project?.............................................30 Potential Effects...............................................................................................................................................................32 What methods were used to evaluate effects on surface waterbodies and water quality?............................................32 Will project construction temporarily affect surface waterbodies and water quality?.....................................................33 Will the project permanently affect surface waterbodies and water quality?..................................................................35 Stormwater detention................................................................................................................................................35 Water quality treatment.............................................................................................................................................37 Will the project have indirect effects on surface waterbodies and water quality?..........................................................40 TABLE OF CONTENTS Renton Nickel Improvement Project ii Surface Water and Water Quality Discipline Report Measures to Avoid or Minimize Project Effects............................................................................................................ 41 How will the project avoid or reduce negative effects to surface water during construction?........................................ 41 How will the project avoid or reduce negative effects to surface water during operation?............................................. 42 References....................................................................................................................................................................... 43 Published Documents.................................................................................................................................................... 43 Websites........................................................................................................................................................................ 43 Appendix A – Pollutant Loading Calculations E XHIBITS Exhibit 1. Project Vicinity Map..........................................................................................................................................1 Exhibit 2. Project Overview Section 1..............................................................................................................................3 Exhibit 3. Project Overview Section 2..............................................................................................................................4 Exhibit 4. Project Overview Section 3..............................................................................................................................5 Exhibit 5. Project Overview Section 4..............................................................................................................................6 Exhibit 6. Project Overview Section 5..............................................................................................................................7 Exhibit 7. Project Overview Section 6..............................................................................................................................8 Exhibit 8. Project Overview Section 7..............................................................................................................................9 Exhibit 9. Project Overview Section 8............................................................................................................................10 Exhibit 10. Surface Waterbodies in the Study Area.......................................................................................................22 Exhibit 11: Threshold Discharge Areas...........................................................................................................................33 Exhibit 12. Stormwater Flow Control Facilities...............................................................................................................36 Exhibit 13. Stormwater Flow Control Facility Locations.................................................................................................37 Exhibit 14. Pollutant Removal Efficiencies for Treatment Facilities ...............................................................................37 Exhibit 15. Pollutant Loadings for Build and No Build Alternatives in lbs/year...............................................................38 Renton Nickel Improvement Project iii Surface Water and Water Quality Discipline Report R:\04156\33-06 Renton Nickel\Task 3 - Discipline Reports\all reports\Final DRs\Renton Nickel Surface Water & WQ DR_final.doc GLOSSARY Adsorption Removal of a pollutant from air or water by collecting the pollutant on the surface of a solid material. Aquifer Protection Zone An area where the project will be required to prevent infiltration of stormwater runoff from the highway. For instance, the City of Renton water supply includes wells that are located in close proximity to the I-405 corridor and Cedar River. Base flow The portion of a stream’s flow that comes from the groundwater. Basin planning programs Basin planning programs contain land use recommendations, regulations, capital projects, and programs to reduce and prevent flooding, erosion, and preserve salmonid habitat in a particular basin. Best management practice Best management practices, referred to commonly as BMPs, are methods used to minimize or avoid effects to water quality such as sediment getting into streams during construction. Examples of BMPs include installing filter fabric fence downstream of all exposed slopes, around existing drainage inlets, and along river, stream, and drainage channels near work areas to prevent sediment-laden stormwater from entering streams. Biofiltration swale These facilities consist of broad, shallow grassy channels that are typically 200 feet long and designed so that stormwater flows slowly through the swale. The vegetation and soil matrix filters and absorbs pollutants from stormwater runoff. Culvert A concrete structure that drains open channels, swales, or ditches under a roadway or embankment. Ecology embankment This consists of a trench dug along side the highway shoulder, lain with perforated pipe, and backfilled with a filtration media. Water from the road flows into the ditch, is filtered by the media, and carried off site by the pipe. Erosion The wearing away of soil or rock by the action of running water, wind, ice, or geologic agents. For this report, erosion relates primarily to stormwater runoff. Falsework The temporary frame that supports the weight of a bridge or other structures during construction. Filter strip These are grassy slopes that filter and diffuse stormwater running off highway shoulders. Flow rates The speed at which a volume of water moves. The flow rate is measured in cubic feet per second. Forest duff Forest duff is both a partially decomposed layer of organic material often bound with fungus, and an extensively decomposed layer. One may find many air voids in the duff region, which can vary in bulk density. The duff region also can vary in thickness from approximately two to twenty centimeters. Impervious surface Surfaces through which water cannot percolate such as pavement, roofs, and compacted or hardened surfaces. Indirect effects Indirect effects are defined in the WSDOT Environmental Procedures Manual as the “effect caused by the proposed action that is later in time or farther removed in distance, but still reasonably foreseeable. Indirect effects may include growth-inducing effects and other effects related to induced changes in the pattern of land use, population density or growth rate, and related effects on air and water and other natural systems, including ecosystems.” Interlocal agreements An agreement between local agencies such as cities and counties. Nutrient Essential chemicals needed by plants and animals for growth, such as phosphorus. GLOSSARY Renton Nickel Improvement Project iv Surface Water and Water Quality Discipline Report Ordinary High Water Mark The line on the shore established by the change in water levels and indicated by physical characteristics such as a clear, natural line impressed on the bank or the presence of litter and debris. The presence and action of water generally leaves an impression on the stream bed and banks that makes a distinct separation between the stream and the adjacent areas and indicates the location of the ordinary high water mark. Peak flows The maximum instantaneous rate of flow during any given storm. Pervious surface A surface through which water can percolate down into the lower layers and eventually into the groundwater. These surfaces are generally vegetated soil areas. Pollutant Generally, any substance introduced into the environment that adversely affects the usefulness of a resource. For this report, pollutants of concern are those that affect water quality and that can enter the surface water as part of the stormwater runoff. Pump station A pump station controls flows to one body of water from another. For this project, the Black River pump station controls flows to the Green River from Springbrook Creek. During flooding, the pump station reduces pumping rates from Springbrook Creek and may suspend pumping entirely if flows in the Green River exceed 12,000 cubic feet per second. Salmonid Any member of the family Salmonidae, which includes all species of salmon, trout, and char (including bull trout). Sediment Material that originates from weathering and erosion of rocks, dirt, or unconsolidated deposits and organic material. Sediment travels through the movement of water, particularly stormwater runoff and is usually suspended within the water. Sedimentation Particles deposited or settling out of the water column and forming sediment on the bed of a channel or water course. Sheet flow Runoff that flows over the ground surface as a thin even layer and not as a concentrated stream or channel. Side channel This is a secondary stream that splits off the main channel. Stormwater The portion of precipitation that does not naturally percolate into the ground or evaporate, but flows overland, in channels, or in pipes into a defined surface water channel or a constructed stormwater facility. Stormwater detention Storing stormwater in manmade facilities such as ponds or vaults and releasing the stormwater at a controlled rate. This process helps control how much and how fast stormwater enters streams and rivers. Controlling the flow of stormwater helps maintain existing flow conditions in the streams and protects streams from possible increases in erosion potential. Tributaries A stream or other body of water that contributes its water to another stream or body of water. Turbidity A condition caused by suspended sediments or floating material that clouds the water and makes it appear dark and muddy. Renton Nickel Improvement Project v Surface Water and Water Quality Discipline Report R:\04156\33-06 Renton Nickel\Task 3 - Discipline Reports\all reports\Final DRs\Renton Nickel Surface Water & WQ DR_final.doc ACRONYMS AND ABBREVIATIONS USED IN THIS REPORT BMPs Best Management Practices cfs Cubic Feet per Second Corps U.S. Army Corps of Engineers CWA Clean Water Act EA Environmental Assessment Ecology Washington State Department of Ecology EIS Environmental Impact Statement EPA U.S. Environmental Protection Agency ESA Endangered Species Act FEMA Federal Emergency Management Agency HPA Hydraulic Project Approval HRM Washington State Department of Transportation Highway Runoff Manual JARPA Joint Aquatic Resource Permit Application NEPA National Environmental Policy Act NPDES National Pollution Discharge Elimination System USDA United States Department of Agriculture PATON Private Aids to Navigation (for non-bridge projects) SMMWW Washington State Department of Ecology Stormwater Management Manual for Western Washington SPCC Spill Prevention, Control, and Countermeasures TDA Threshold Discharge Areas TMDL Total Maximum Daily Load TSS Total Suspended Solids FAA Federal Aviation Administration WRIA Watershed Resource Inventory Area WSDOT Washington State Department of Transportation Renton Nickel Improvement Project vi Surface Water and Water Quality Discipline Report This page intentionally blank. Renton Nickel Improvement Project Surface Water and Water Quality Discipline Report 1 R:\04156\33-06 Renton Nickel\Task 3 - Discipline Reports\all reports\Final DRs\Renton Nickel Surface Water & WQ DR_final.doc INTRODUCTION What is the Renton Nickel Improvement Project? The Renton Nickel Improvement Project is a highway expansion project that will improve mobility and safety through Tukwila and Renton. On I-405, this project begins just east of the I-5/I-405 interchange in Tukwila and extends north past the Cedar River to the SR 169 (Maple Valley Highway) interchange. The project will build an additional lane both northbound and southbound between I-5 and SR 169. On SR 167, the project will extend the southbound high-occupancy vehicle (HOV) lane north to I-405 and add a southbound auxiliary lane from I-405 to the SW 41st Street off-ramp. These limits comprise the study area for the project. Prior to planning this specific project, WSDOT created the I-405 Corridor Program. This program provides a comprehensive strategy to reduce congestion and improve mobility throughout the I-405 corridor. The corridor begins at the I-5 interchange in the city of Tukwila and extends northward 30 miles to the I-5 interchange in the city of Lynnwood. The program’s purpose is to provide an efficient, integrated, and multimodal system of transportation solutions. Using the I-405 Corridor Program’s Selected Alternative as the Master Plan to improve I-405, WSDOT developed relatively low cost, congestion relief roadway improvements as an interim step in achieving the Master Plan. As part of this effort, WSDOT began to define the Renton Nickel Improvement Project. The Renton Nickel Improvement Project was developed as part of a first step in providing a focused strategy to improve I-405 between I-5 in Tukwila and SR 169 in Renton and SR 167 southbound from I-405 to SW 41st Street, see Exhibit 1. This discipline report analyzes two project alternatives: the No Build Alternative and the Build Alternative. Exhibit 1. Project Vicinity Map G r e en R i v e r C e d ar Riv er Interurban TrailCedar River Interpretive Trail Panther Creek Wetlands Green River TrailBlack River Riparian Forest Fort Dent Park Cedar River Park Liberty Park SW 41st St S W 3 4 t h S t S W 2 7 t h S t SW 16th St Southcenter ParkwayW Valley HwyI n t e r u r ban Ave SMa ple V alley H w yRainier Ave SS W Sun s e t B lvdS W 7 t h S t S W G r a d y W a y Lind Ave SWTUKWILA RENTON S pri n g br ook CreekBenson Rd SSW 23rd St Talbot Rd SBenson Dr SI-405 Northern Project Limit at SR 169 I-405 Southern Project Limit at I-5 !"`$ %&e( Aæ Aç Aí SR 167 Southern Project Limit at SW 41st St 0 0.25 0.5 Miles M AÅ Arterial Road Freeway Trail Stream Lake Park Municipality INTRODUCTION Renton Nickel Improvement Project 2 Surface Water and Water Quality Discipline Report What is the No Build Alternative? The No Build Alternative assumes that only routine activities such as road maintenance, repair, and safety improvements would take place over the next 20 years. This alternative does not include improvements to increase roadway capacity or reduce congestion. For these reasons, it does not satisfy the project’s purpose—improve I-405 between I-5 in Tukwila and SR 169 in Renton and SR 167 southbound from I-405 to SW 41st Street. The No Build Alternative has been evaluated in this discipline report to establish a baseline for comparing the effects associated with the Build Alternative. What is the Build Alternative? The new lanes that will be built under this project are: An I-405 northbound general-purpose (GP) lane from I-5 to the SR 167 off-ramp. An I-405 northbound auxiliary lane from the SR 167 to I-405 on-ramp to the SR 169 off-ramp. An I-405 southbound auxiliary lane from the SR 169 to I-405 on-ramp to the SR 167 off-ramp. An I-405 southbound GP lane from the SR 167 to I-405 on-ramp to the I-5 off-ramp. A SR 167 southbound auxiliary lane from I-405 to the SW 41st Street off-ramp. Also, the existing inside HOV lane will be extended north to I-405 from its present starting point in the vicinity of SW 21st Street. See Exhibits 2 through 9 show the project features. In addition to adding lanes to I-405 and SR 167, this project will provide the following improvements. Improve Interchanges Minor modifications will be made to the ramps at the SR 167 interchange: The one-lane ramp from northbound I-405 to SR 167 will be widened to a 2-lane off connection, which provides a dedicated lane to southbound SR 167 and a dedicated lane to northbound Rainer Avenue. See Exhibit 5. Traffic from two consecutive single-lane on- ramps from southbound I-405 to SR 167 will be separated by a concrete barrier. This will provide a smoother transition to the mainline and reduce congestion on the on-ramps. What is an auxiliary lane? An auxiliary lane is a lane added between interchanges—from one on-ramp to the next off-ramp. It is dedicated to traffic entering and leaving the freeway and provides motorists with more time and extra room to accelerate or decelerate and merge when getting on and off the freeway. 89:P 89:T Existing On-ramp On-ramp with proposed auxiliary lane INTRODUCTION Renton Nickel Improvement Project Surface Water and Water Quality Discipline Report 3 T u k w i l a P a r k w a y I-405 Southern Project Limit at I-5 Gilliam Creek Cottage Creek Westfield Shoppingtown MallSouthcenter ParkwaySouthcenter Blvd 65th Ave STUKWILA RENTON!"`$ %&e( Sec. 1 Sec. 2 Sec. 3 Sec. 4 Sec. 5 Sec. 6 Sec. 7 Aæ Aç Sec. 8 Aí I-405 Northboundbound Improvements: A general-purpose lane will be added by restriping the existing pavement and adding pavement up to 15 feet to the outside at some locations. I-405 Southbound Improvements: A general-purpose lane will be added by restriping the existing pavement and adding pavement up to 15 feet to the outside at some locations. M0250500 Feet I-405 NORTHBOUND Existing Proposed I-405 SOUTHBOUND Existing Proposed Renton Renton Piped River/Creek Channel Open River/Creek Channel Ecology EmbankmentÃÃÃÃÃÃÃÃÃÃÃÃ Retaining Wall Stormwater Flow Control Facility New Pavement Easement Acquisition Parcel Acquisition Existing ROW Areas of Construction New ROW Exhibit 2. Project Overview Section 1 INTRODUCTION Renton Nickel Improvement Project 4 Surface Water and Water Quality Discipline Report ÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃInterurban TrailFort Dent Park W Valley HwyInterurban Ave S RENT ONT UKWI L AG r e en RiverSouthcenter B lv d65th Ave SAí %&e( %&e(UP RRBNSF RRBridge Restripe Only Bridge Rail Replacement Bridge Rail Replacement M o n s t e r R d S WTUKWILA RENTON!"`$ %&e( Sec. 1 Sec. 2 Sec. 3 Sec. 4 Sec. 5 Sec. 6 Sec. 7 Aæ Aç Sec. 8 Aí I-405 Northbound Improvements: A general-purpose lane will be added by restriping the existing pavement and adding pavement up to 15 feet to the outside at some locations. I-405 Southbound Improvements: A general-purpose lane will be added by restriping the existing pavement and adding pavement up to 15 feet to the outside at some locations. M0250500 Feet I-405 SOUTHBOUND Existing Proposed Renton Renton I-405 NORTHBOUND Existing Proposed %&e( Retaining Wall Piped River/Creek Channel Open River/Creek Channel ÃÃÃÃÃÃÃÃÃÃÃÃ Ecology Embankment Stormwater Flow Control Facility New Pavement Areas of Construction Easement Acquisition Parcel Acquisition Existing ROW New ROW Exhibit 3. Project Overview Section 2 INTRODUCTION Renton Nickel Improvement Project Surface Water and Water Quality Discipline Report 5 ÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃ SW 16th St S W G r a d y W a y SW G ra d y W a y Oakesdale Ave SWSW 16th St %&e( Potential Staging Area Bridge Replacement S prin g br o o k Cr eekBridge Replacement TUKWILA RENTON!"`$ %&e( Sec. 1 Sec. 2 Sec. 3 Sec. 4 Sec. 5 Sec. 6 Sec. 7 Aæ Aç Sec. 8 Aí I-405 Northbound Improvements: A general-purpose lane will be added by restriping the existing pavement and adding pavement up to 15 feet to the outside at some locations. The existing Springbrook Creek and Oakesdale Avenue bridges will be replaced and the existing culvert will be removed. I-405 Southbound Improvements: A general-purpose lane will be added by restriping the existing pavement and adding pavement up to 70 feet to the outside at some locations. The existing Springbrook Creek and Oakesdale Avenue bridges will be replaced and the existing culvert will be removed.M0250500 Feet I-405 SOUTHBOUND Existing Proposed Renton Renton I-405 NORTHBOUND Existing Proposed Piped River/Creek Channel Open River/Creek Channel ÃÃÃÃÃÃÃÃÃÃÃÃ Ecology Embankment Retaining Wall Stormwater Flow Control Facility New Pavement Areas of Construction Easement Acquisition Parcel Acquisition Existing ROW New ROW Exhibit 4. Project Overview Section 3 INTRODUCTION Renton Nickel Improvement Project 6 Surface Water and Water Quality Discipline Report ÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃ SW 19th StLind Ave SWS G r a d y W a y Aæ %&e( Potential Staging Area Noise Wall Renton CinemaRolling Hills Creek Panther Creek Wetlands SW 16th St Lake AveSouthRainier Ave STUKWILA RENTON!"`$ %&e( Sec. 1 Sec. 2 Sec. 3 Sec. 4 Sec. 5 Sec. 6 Sec. 7 Aæ Aç Sec. 8 Aí I-405 Northbound Improvements: A general-purpose lane will be added up to the SR 167 interchange and an auxiliary lane will be added from the SR 167 to I-405 on-ramp north. These lanes will be added by restriping the existing pavement and adding pavement up to 15 feet to the outside at some locations. I-405 Southbound Improvements: An auxiliary lane will be added up to the I-405 to SR 167 on-ramp and a general-purpose lane will be added south of the interchange. These lanes will be added by restriping the existing pavement and adding pavement up to 15 feet to the outside at some locations. SR 167 Southbound Improvements: An auxiliary lane will be added by restriping existing pavement and adding up to 19 feet of pavement at the outside at some locations. The existing HOV lane will be extended north from SW 21st Street to the interchange with I-405.M0250500 Feet I-405 SOUTHBOUND Existing Proposed Renton Renton I-405 NORTHBOUND Existing Proposed SR 167 SOUTHBOUND Existing Proposed Renton ÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃ ÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃ Piped River/Creek Channel Open River/Creek Channel Proposed Noise Wall ÃÃÃÃÃÃÃÃÃÃÃÃ Ecology Embankment Retaining Wall Stormwater Flow Control Facility New Pavement Areas of Construction Easement Acquisition Parcel Acquisition Existing ROW New ROW Exhibit 5. Project Overview Section 4 INTRODUCTION Renton Nickel Improvement Project Surface Water and Water Quality Discipline Report 7 ÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃPanther Creek Wetlands S W 2 7 t h S t Talbot Rd SEast Valley RdTalbot Rd SPotential Staging Area SW 23rd St TUKWILA RENTON!"`$ %&e( Sec. 1 Sec. 2 Sec. 3 Sec. 4 Sec. 5 Sec. 6 Sec. 7 Aæ Aç Sec. 8 Aí SR 167 Improvements: In addition to extending the HOV lane north from SW 21st Street, an auxiliary lane will be added by restriping the existing pavement and adding pavement up to 19 feet to the outside at some locations. M0250500 Feet SR 167 SOUTHBOUND Existing Proposed Renton RentonÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃ Piped River/Creek Channel Open River/Creek Channel ÃÃÃÃÃÃÃÃÃÃÃÃ Ecology Embankment Retaining Wall Stormwater Flow Control Facility New Pavement Areas of Construction Easement Acquisition Parcel Acquisition Existing ROW New ROW Exhibit 6. Project Overview Section 5 INTRODUCTION Renton Nickel Improvement Project 8 Surface Water and Water Quality Discipline Report ÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃSW 41st St S W 3 3 r d S t Panther CreekEast Valley RdTalbot Rd SLind Ave SWAæ SR 167 Southern Project Limit at SW 41st St TUKWILA RENTON!"`$ %&e( Sec. 1 Sec. 2 Sec. 3 Sec. 4 Sec. 5 Sec. 6 Sec. 7 Aæ Aç Sec. 8 Aí SR 167 Improvements: An auxiliary lane will be added by restriping the existing pavement and adding pavement up to 19 feet to the outside at some locations. The new lane will tie into the existing ramp connection to SW 41st Street. M0250500 Feet SR 167 SOUTHBOUND Existing Proposed Renton Renton Piped River/Creek Channel Open River/Creek Channel ÃÃÃÃÃÃÃÃÃÃÃÃ Ecology Embankment Retaining Wall Stormwater Flow Control Facility New Pavement Areas of Construction Easement Acquisition Parcel Acquisition Existing ROW New ROW Exhibit 7. Project Overview Section 6 INTRODUCTION Renton Nickel Improvement Project Surface Water and Water Quality Discipline Report 9 ÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃS G rady W ayB e a c o n S 7 t h S tWilliams %&e( Potential Staging Area Replace Bridge Bridge Widening Existing Bridge to be Demolished Thunder Hills Creek Rolling Hills Creek Noise Wall Benson Rd STalbot Rd STUKWILA RENTON!"`$ %&e( Sec, 1 Sec. 2 Sec. 3 Sec. 4 Sec. 5 Sec. 6 Sec. 7 Aæ Aç Sec. 8 Aí I-405 Northbound Improvements: An auxiliary lane will be added by restriping the existing pavement and adding pavement up to 15 feet to the outside at some locations. I-405 Southbound Improvements: An auxiliary lane will be added by restriping the existing pavement and adding pavement up to 24 feet to the outside at some locations. Benson Rd S Improvements: The Benson Rd S overpass will be replaced and realigned to the west of its current location. The new overpass will have 2 lanes with 5-foot bike lanes on both sides and a 6-foot sidewalk on the west side.M0250500 Feet I-405 NORTHBOUND Existing Proposed I-405 SOUTHBOUND Existing Proposed Renton Renton Parcel Acquisition New ROW Existing ROW Easement Acquisition Areas of Construction New Pavement Stormwater Flow Control Facility Retaining Wall ÃÃÃÃÃÃÃÃÃÃÃÃ Ecology Embankment Proposed Noise Wall Piped River/Creek Channel Open River/Creek Channel Exhibit 8. Project Overview Section 7 INTRODUCTION Renton Nickel Improvement Project 10 Surface Water and Water Quality Discipline Report C edar River Cedar River Interpretive Trail Cedar River Park Liberty Park Ma p l e V a ll e y H w y H o u s e r W a y S N 3 r d S t Bronson Wa y N%&e( I-405 Northern Project Limit at SR 169 Aç Restripe Only Main AvenueCedar Ave SRenton Ave STUKWILA RENTON!"`$ %&e( Sec. 1 Sec. 2 Sec. 3 Sec. 4 Sec. 5 Sec. 6 Sec. 7 Aæ Aç Sec. 8 Aí I-405 Northbound Improvements: An auxiliary lane will be added by restriping the existing pavement and adding pavement up to 15 feet to the outside at some locations. I-405 Southbound Improvements: An auxiliary lane will be added by restriping the existing pavement and adding pavement up to 15 feet to the outside at some locations. M0250500 Feet I-405 NORTHBOUND Existing Proposed I-405 SOUTHBOUND Existing Proposed Renton Renton Piped River/Creek Channel Open River/Creek Channel ÃÃÃÃÃÃÃÃÃÃÃÃ Ecology Embankment Retaining Wall Stormwater Flow Control Facility New Pavement Areas of Construction Easement Acquisition Parcel Acquisition Existing ROW New ROW Exhibit 9. Project Overview Section 8 INTRODUCTION Renton Nickel Improvement Project Surface Water and Water Quality Discipline Report 11 Improve Benson Road The Benson Road overpass will be replaced and realigned to accommodate the southbound auxiliary lane on I-405 as well as future improvements to I-405 as shown on Exhibit 8. Improvements on Benson Road include a 6-foot sidewalk on the west side and 5-foot bike lanes on both sides. Widen and replace bridges Several bridges within the study area will be widened or replaced based on present location, cost, and existing soil conditions. To construct the new lanes, the project will: Widen Talbot Road Bridge on both the northbound and the southbound sides. See Exhibit 8. Replace Springbrook Creek Side Channel Bridge and Oakesdale Avenue Bridge with new southbound and northbound structures and remove the Springbrook Creek box culvert. See Exhibit 4. Replace the rail on the I-405 bridges over SR 181 and the Union Pacific and Burlington Northern Santa Fe railroads. The project will not affect the I-405 bridges over the Green River, Lind Avenue, or the Cedar River. The project will also not affect the Cedar Avenue or Renton Avenue overpasses. The roadway will be restriped in these areas to accommodate the new lanes. Use retaining walls Widening I-405 and SR 167 will require retaining walls to minimize the construction footprint and right-of-way acquisition. Retaining walls will also help avoid and minimize effects to wetlands and other sensitive areas. Improve culverts WSDOT anticipates that construction will affect some existing stormwater cross culverts and one stream culvert. Associated culvert improvements include extending the existing structures due to widening the roadway and stabilizing culvert ends with rock or retaining walls. The I-405 Team will conduct a hydraulic analysis of the culverts to ensure that the modifications will have no effect on the base flood elevations. See the Fisheries and Aquatic Resources Discipline Report for detailed discussion on fish passage. Why rebuild Benson Road on a new alignment over I-405? By building the new overpass to the west on a new alignment, the new structure can be constructed while the existing structure remains open to traffic. Traffic can then be shifted onto the new structure, while the old overpass is demolished. What does a “rail” replacement involve? Typically, a bridge rail replacement project consists of making minor adjustments to the width of the bridge deck and replacing the guard rail or barrier. This type of project does not include adding new bridge columns or footings. INTRODUCTION Renton Nickel Improvement Project 12 Surface Water and Water Quality Discipline Report Build a noise wall One noise wall will be built on the northbound side of the freeway as shown on Exhibits 5 and 8. The wall will begin at the intersection of South 14th Street and South 15th Street and follow South 14th Street east to Talbot Road. This wall will be approximately 2,150 feet long and 18 feet tall. How will stormwater from the project be managed? Stormwater from the project will be managed for both quality and peak flows using currently accepted best management practices (BMPs). The I-405 Team has designed the stormwater management facilities to comply with the following guidelines and procedures: WSDOT Highway Runoff Manual M 31-16 WSDOT Hydraulics Manual M 23-03 Stormwater treatment facilities The project will add new impervious surface within the study area, most of which will be within the Springbrook Creek basin. This project will treat runoff for an area equal to 100 percent of these new surfaces. The project will use BMPs that the HRM lists as enhanced treatment facilities. The I-405 Team has proposed that stormwater be treated using a combination of these facilities. In most of the study area, ecology embankments will be used to capture runoff from the edge of the pavement and provide water quality treatment. Ecology embankments also serve to convey treated runoff to receiving waters or to flow control facilities as required. The project also includes a combined stormwater quality wetland and detention facility that addresses water quality and flow control in one facility. Exhibits 2 through 9 show the location of stormwater facilities that will be built for this project. Ecology Embankment Cross-Section What are the guidelines for stormwater management facilities? Water quality treatment will be provided for an area equal to the new impervious surfaces created on the project. Impervious surfaces, such as pavement, are those that do not allow water to penetrate into the ground. Stormwater from new impervious surfaces or an equal area will be controlled in detention facilities. This process allows water to be held (detained) and thus released at rates that are equal to existing conditions. INTRODUCTION Renton Nickel Improvement Project Surface Water and Water Quality Discipline Report 13 Drainage Collection and Conveyance Some changes to existing drainage will be necessary to provide flow control and water quality treatment to address the new impervious area added by the project. However, existing storm drainage systems will be kept to the greatest extent possible and existing flow patterns will be maintained. Where roadway widening affects drainage ditches that convey water from adjacent private properties, the project design will assure that existing conveyance capacities are maintained. What environmental and utilities issues influenced the project design and what was done to avoid and minimize project effects? Throughout the development of the Renton Nickel Improvement Project design, environmental elements were reviewed and design features were modified to avoid or minimize negative effects to the environment. Influence on the project design came from: Soil Conditions: the soils in the project area are highly prone to accentuate earthquake shaking, which influences how bridges can be widened or replaced. Noise: highway noise in the project area already exceeds acceptable levels, which means that including noise walls as part of the project had to be considered. Wetland Locations: many wetlands are located along the edges of the highway, which influence whether the widened sections will use retaining walls or fill slopes. Historical Sites: some historic sites exist within the study area, so the project design was coordinated to avoid these properties. Because the I-405 Team planned for these environmental considerations, several design features have the benefit of avoiding or minimizing potential effects due to the project. These design features are described from south to north below. I-405, I-5 to SR 167 WSDOT will construct a retaining wall from west of the 68th Avenue structure over I-405 at Tukwila Parkway What are detention facilities? These facilities control stormwater runoff so that it can be released at a controlled rate. Two types are commonly used: Ponds. Vaults. Similar to a pond, but with a hard-sided construction. These concrete structures function like a pond but also provide detention storage. INTRODUCTION Renton Nickel Improvement Project 14 Surface Water and Water Quality Discipline Report The proposed design modifications allow the additional lanes to be added over the Green River by restriping instead of bridge widening. This avoids effects on the river, stream habitat, floodplain, and Interurban Trail. to the Green River. This wall avoids the need to construct a fill slope that would extend into Gilliam Creek. See Exhibit 2. WSDOT will provide a narrower outside shoulder on northbound I-405 at the Green River Bridge. The shoulder will vary from 10 to just over 3 feet at the west abutment of the existing bridge. Narrowing the shoulder avoids modifications to the existing bridge. As a result, the design also avoids effects to the river, the 100-year floodplain, the ordinary high water level, and adjacent riparian zones. At the SR 181 interchange, the bridge and ramp will be restriped to provide the new general-purpose lane and ramp improvements. This approach minimizes the need to widen the existing SR 181 Bridge, reconstruct the SR 181 interchange, or modify the Southcenter Boulevard crossing of the Green River. This in turn avoids relocating or diverting the Interurban Trail, which goes under the bridge. See Exhibit 3. Near the Westfield Shoppingtown Mall, a large Seattle Public Utilities water transmission line parallels I-405. WSDOT will line this pipe so that is can support the loads from the new roadway embankment. This approach allows the line to stay in its present location. WSDOT will remove the existing I-405 bridges over the Springbrook Creek side channel and Oakesdale Avenue and replace them with a single northbound and a single southbound bridge. This approach will allow for the removal of the Springbrook Creek box culvert. Construction of the new bridges will be phased with the southbound bridge built slightly to the north of the existing roadway. This phasing minimizes the need to construct temporary roadway to maintain traffic operations. WSDOT also evaluated the location of the new bridge piers and selected locations that will minimize the effect on the existing stream, stream buffer, and trail that crosses under the bridge. WSDOT will construct a narrower exit gore from I-405 to the northbound ramp at the SR 167 interchange as shown in Exhibit 5. By building a narrower exit gore, the project can be constructed within the existing right- of-way. This has the benefit of avoiding right-of-way acquisition, avoiding effects to the wetland outside the right-of-way, and avoiding effects to the existing Lind Avenue Bridge. What is an exit gore? An exit gore is a roadway feature that separates an exiting lane from the main lanes. An exit gore can be defined either by paint stripes, raised buttons, physical barriers, or a combination of these. INTRODUCTION Renton Nickel Improvement Project Surface Water and Water Quality Discipline Report 15 Retaining walls will help to avoid and minimize effects on the Panther Creek wetlands along SR 167 SR 167, southbound from I-405 to SW 41st Street WSDOT will build a retaining wall along a large portion of the west edge of SR 167 southbound instead of an earth fill slope. See Exhibits 6 and 7. The retaining wall minimizes effects on three wetlands. The retaining wall has the added benefit of minimizing right-of-way needs and reduces the effect on existing utility crossings, in particular, the City of Seattle’s 60- inch water line and Olympic Petroleum’s two high pressure pipelines, which all cross under SR 167. I-405, SR 167 to SR 169 WSDOT will add a lane by restriping I-405 northbound next to the Talbot Hill retaining wall immediately east of the SR 167 interchange. Restriping instead of widening avoids the need to reconstruct the existing Talbot Hill retaining wall and avoids effects on properties south of I-405 in this area. Between Talbot Road and the “S-Curves”, northbound I-405 will be widened to achieve standard lane and shoulder widths. Most of this length will be supported by retaining walls to minimize effects to Thunder Hills Creek, adjacent properties, and the existing cut slope south of I-405. To support the fill required to widen the roadway on the north side of I-405 next to the outfall for the original Rolling Hills Creek culvert, the design uses a retaining wall. By using the retaining wall, the project improvements at this location can be constructed without affecting the existing culvert. WSDOT will use a non-standard design for the I-405 to SR 167 exit ramp. The changes from the design standards include not providing a recovery lane, narrowing the distance between the through lane and ramp, and providing narrower shoulders. While these changes deviate from WSDOT design standards they are an improvement over existing conditions. These features will avoid effects to the existing Rolling Hills Creek/Thunder Hills Creek channel located between I-405 and the Renton Cinema complex as shown in Exhibit 5. Using retaining walls along the west side of Benson Road avoids effects to Rolling Hills Creek and the wetlands east of Talbot Road. WSDOT will use retaining walls to support widening southbound I-405 south of the Cedar Avenue overpass. Using retaining walls versus a fill slope, avoids encroaching on Cedar Avenue and Main Avenue in Renton. What is a recovery lane? A recovery lane is a paved area adjacent to an off-ramp. This area gives drivers, who find themselves exiting the freeway unintentionally, room to maneuver back onto the freeway. INTRODUCTION Renton Nickel Improvement Project 16 Surface Water and Water Quality Discipline Report WSDOT also plans to replace the existing Benson Road overpass on a new alignment. The new bridge will be located slightly to the west of the existing bridge. This will allow traffic to continue to use the existing overpass until the new one is completed. This will minimize disruption for local traffic and to emergency response vehicles. Where northbound and southbound I-405 passes under the Renton Avenue and Cedar Avenue overpasses, WSDOT will add lanes by restriping. This design avoids replacing the two overpasses; however, the available area does not allow the standard shoulder and lane widths. WSDOT shifted a proposed stormwater facility to avoid effects to the existing Renton Coal Mine Hoist Foundation site south of Benson Road. This site is on the Washington Historic Register. What is planned for wetland and stream mitigation? WSDOT will compensate for unavoidable effects to wetlands with credits from the Springbrook Creek Wetland and Habitat Mitigation Bank. Mitigation is needed for 1.66 acres of wetlands. The Springbrook Creek Wetland and Habitat Mitigation Bank is being developed as a joint effort between WSDOT and the City of Renton. This ‘bank’ will construct a new high quality wetland complex that will serve to replace other wetlands that are filled in by projects such as the Renton Nickel Improvement Project. The location of the bank is shown to the left. In addition to wetland mitigation, the site will also provide flood storage mitigation. The Springbrook Creek Wetland and Habitat Mitigation Bank will be one of the first urban mitigation banks to be certified in Washington. To mitigate project effects on streams, WSDOT will remove the existing Springbrook Creek box culvert. With the new I-405 southbound and northbound bridges that will span both Springbrook Creek and Oakesdale Avenue, the box culvert is no longer needed. After the new bridges are in place, the box culvert will be removed and the streambed in that area will be restored. This will improve fish habitat within Springbrook Creek. Any additional stream mitigation required to offset project effects will be accommodated within the project vicinity. Renton Coal Mine Hoist Foundation site looking west r Interurban TrailPanther Creek Wetlands Green River TrailFort Dent Park SW 41st St S W 3 4 t h S t S W 2 7 t h S t SW 16th St W Valley HwyS W 7 t h S t S W G r a d y W a y Lind Ave SWS pri n g br ook CreekSW 23rd St Aæ Aí M 0 0.25 0.5 Miles 100 Year Floodplain 500 Year Floodplain Park Renton Tukwila Springbrook Creek Wetland & Habitat Mitigation Bank Wetlands Local Road Legend Trail Arterial Road Freeway River/Creek Channel Study Area Limits Springbrook Creek Wetland and Habitat Mitigation Bank INTRODUCTION Renton Nickel Improvement Project Surface Water and Water Quality Discipline Report 17 What benefits will the project provide? The Build Alternative will benefit the area by reducing congestion at chokepoints, reducing the duration of congestion during peak commuter travel hours, and improving freight movement. This section of I-405, from the I-5 interchange to SR 169, is congested due to large traffic volumes and merging and diverging traffic. The new lanes will help relieve congestion by adding roadway capacity. This in turn will improve safety by providing drivers with more time and extra room to accelerate or decelerate and move into and out of the stream of traffic when getting on and off the freeway. This provides a smoother transition for motorists as they get on and off I-405 in Tukwila and Renton and helps decrease rear- end and sideswipe collisions. The project reduces congestion approaching the SR 167 interchange, and it complements the completed southbound I-405 to southbound SR 167 flyover ramp. This project will construct one noise wall along northbound I-405 from the intersection of South 14th Street and South 15th Street east to Talbot Road. This wall will benefit residents in that area by lowering the overall noise levels. Another benefit of this project is that it continues the application of the Context Sensitive Solutions (CSS) design choices made by the communities within the I-405 corridor. The Benson Road realignment will reflect the most comprehensive application of these design choices as explained further in the next section. How will the project incorporate community design preferences? The Renton Nickel Improvement Project is being planned, developed, and designed according to CSS guidelines. These guidelines establish the community design preferences used to design the project features. Working within the framework for the overall I-405 corridor, the Urban Design Guidelines will be adapted to incorporate the communities’ design preferences. These preferences will be included in the contract documents prepared for the Renton Nickel Improvement Project. The selected I-405 theme of “Culture, Nature, and Progress,” with nature This rendering shows the new Benson Road overpass with the CSS Guidelines applied INTRODUCTION Renton Nickel Improvement Project 18 Surface Water and Water Quality Discipline Report being the dominant theme, will be carried into corridor- wide and local I-405 designs. The new Benson Road overpass is the main project feature that will receive CSS treatment. The new southbound and northbound bridges over Springbrook Creek and Oakesdale Avenue will also receive CSS treatments. The rest of the project elements will be designed to match in color and vegetation type only, as many of these elements will be affected by construction of future Master Plan projects. During future Master Plan phases for the overall I-405 corridor, the approved CSS guidelines will be applied throughout. How will the project be constructed? Construction of the entire Renton Nickel Improvement Project is expected to take two years, beginning in early 2008 and being completed in late 2010. However, construction activity will not be constant for the entire study area throughout this time, and in some locations, the work will take substantially less time than two years. Construction will pose some minor inconveniences because of localized travel delays due to temporary lane closures and narrowed lanes and shoulders. At-grade construction At-grade construction, which occurs on the same elevation as the existing lanes, will be staged to minimize traffic delays and detours. Typically, lanes are shifted toward the median. WSDOT then places a concrete barrier to close off the shoulder. Staging allows construction to occur safely without closing lanes for the duration of construction. Access to construction areas will occur from the roadway side to minimize property effects. Bridge construction Construction of the I-405 bridges will occur in multiple stages to minimize traffic delays and detours. The following describes typical staging for bridge construction. As the first stage, traffic is shifted toward the I-405 median and the existing lanes and shoulders are narrowed slightly to allow widening of the existing structure or construction of the new bridge depending on the design. In the next stage, traffic is shifted onto the new bridge area. If the bridge is being replaced rather than simply widened, the old structure is demolished after traffic is shifted to the new bridge. At-grade construction for this project will likely be staged similar what is shown above. Here, the southbound lanes of I-5 were shifted toward the median and a concrete barrier closed off the shoulder to provide crews a safe work area. INTRODUCTION Renton Nickel Improvement Project Surface Water and Water Quality Discipline Report 19 The new Benson Road overpass will also be staged. The new structure will be built to the west, while the existing overpass remains in service. After traffic has been shifted onto the new overpass, the existing structure will be demolished. Staging areas Construction staging areas along I-405 and SR 167 will be within the WSDOT right-of-way. Potential staging areas have been identified as shown on Exhibits 2 through 9. Traffic control Detour agreements with the local agencies will be obtained after WSDOT awards the contract. A traffic control plan will be approved by WSDOT prior to starting construction. The plan’s primary objectives will be to provide a safe facility, to streamline the construction schedule, and to minimize reductions to existing traffic capacity. To lessen effects on traffic, the duration of activities will be minimized and reductions in capacity will be limited and will be targeted to a period when they will have the least effect. Why do we consider surface water and water quality for this project? Surface water is an important resource for people and all other animals and plants. For this reason, the federal government drafted the Clean Water Act to protect surface waters. This act requires that State Water Quality Standards set limits on pollution in our lakes, rivers, and marine waters to protect water quality for beneficial uses such as drinking water supply, aquatic life habitat, agricultural needs, and recreational purposes. Within the study area, surface water is an important resource to humans and the environment. Historically, adding impervious surface area has been known to affect water quality and the quantity of runoff. Because the Renton Nickel Improvement Project will add impervious surface area to the Cedar River basin, Springbrook Creek basin, and Green River basin, this discipline report investigates the effects this project will have and determines if any additional measures are required to reduce potential effects. What is surface water? Surface water refers to flowing or standing water in streams, lakes, and wetlands. It also refers to water flowing off of roadways during rain events as stormwater. INTRODUCTION Renton Nickel Improvement Project 20 Surface Water and Water Quality Discipline Report What are the key points of this report? The key points of this report are: Runoff from the new pollution generating impervious surfaces or an equivalent area will be treated for water quality. Changes in pollutant loading are expected to be negligible. Runoff increases from the new impervious area will be mitigated using detention facilities. Since the flow/duration relationships are maintained through detention design, no effect on peaks or flow durations are expected. The WSDOT Highway Runoff Manual provides guidance on project design to avoid and minimize negative effects on surface waters and water quality. WSDOT will meet the manual’s requirements by implementing an array of treatment best management practices (BMPs) as well as other protection measures. These measures will be sufficient to reduce potential surface water effects to non- measurable levels. Water quality treatment will be achieved by incorporating ecology embankments, constructed stormwater treatment wetlands, and other enhanced water quality treatment BMPs into the facility designs. WSDOT will also prepare a Temporary Erosion and Sediment Control Plan that will be in place prior to starting construction. This plan will address the specific measures that will be used to manage stormwater during construction. WSDOT will also prepare a Spill Prevention, Control and Countermeasures Plan prior to construction that will be followed by the contractor to reduce the risk of accidental spills during construction. Renton Nickel Improvement Project Surface Water and Water Quality Discipline Report 21 EXISTING CONDITIONS What information was collected to identify surface waterbodies, existing stormwater facilities, and water quality? The project team conducted a field investigation to examine surface water resources along the project corridor to verify and update drainage mapping. Aerial photographs, topographic survey data, and drainage maps were used to help the team identify flow pathways, outfalls, and existing stormwater facilities. The team determined the existing surface waterbody conditions using data provided by the Washington State Department of Ecology (Ecology), including Watershed Resource Inventory Area (WRIA) maps. WRIAs are the major watershed drainage areas that Ecology uses to track water quality data and plan and manage water resources. Other relevant data that the team reviewed included Ecology’s 2004 303(d) list of impaired waterbodies. Every two years states are required to prepare a list of waterbody segments that do not meet state water quality standards. The Total Maximum Daily Load (TMDL) list, which is prepared by Ecology, was also reviewed. A TMDL establishes the mechanisms to implement water quality standards for an impaired waterbody. The TMDL establishes the allowable loadings of pollutants to a waterbody so that it achieves state water quality standards. City of Renton, City of Tukwila, and King County personnel provided additional surface water and water quality data and information. What surface waterbodies are present in the study area? Exhibit 10 shows that the project primarily crosses the Green River Valley (WRIA 8). Tributaries to the Green River in the study area include Cottage Creek, Gilliam Creek, an un-named tributary to Gilliam Creek, Springbrook Creek, Panther Creek, Rolling Hills Creek, an un-named tributary to Rolling Hills Creek, and Thunder Creek. What is the Ecology 303(d) List? The federal Clean Water Act (CWA), adopted in 1972, requires states to restore their waters to be “fishable and swimmable.” The Clean Water Act established a process to identify and clean up polluted waters. Every two years, all states are required to prepare a list of waterbodies that do not meet water quality standards. This list is called the 303(d) list because the process is described in Section 303(d) of the Clean Water Act. Ecology has prepared a preliminary assessment of water quality in Washington. The assessed waters are listed in categories that describe the status of water quality. For those waters that are in the polluted category, beneficial uses—such as drinking, recreation, aquatic habitat, and industrial use—are impaired by pollution. What is a total maximum daily load (TMDL)? A TMDL is part of the water clean up plan for each waterbody on the 303(d) list. It is a calculation of the maximum amount of a pollutant that a waterbody can receive and still meet State water quality standards. Percentages of the total maximum daily load are allocated to the various pollutant sources. EXISTING CONDITIONS Renton Nickel Improvement Project 22 Surface Water and Water Quality Discipline Report As shown in Exhibit 1, the northern end of the project crosses the Cedar River (WRIA 9). Black River Riparian Forest Fort Dent Park Cedar River Park Liberty Park SW 41st St S W 3 4 t h S t S W 2 7 t h S t SW 16th St Southcenter ParkwayW Valley HwyI n t e r u r ban Ave SMa p le V alley H w yRainier Ave SS W Sun s e t B lvdS W 7 t h S t S W G r a d y W a y Lind Ave SWTUKWILA RENTON I-405 Northern Project Limit at SR 169 I-405 Southern Project Limit at I-5 SR 167 Southern Project Limit at SW 41st St Benson Rd SSW 23rd St Talbot Rd SBenson Dr SAæ Aç !"`$ Aí %&e( Unnamed Tributary to Rollings Hills Creek Rolling Hills Creek Panther Creek Gilliam Creek Mill Creek Green River Springbrook Creek Cedar River Panther Creek Wetlands Thunder Hills Creek Cottage Creek Unnamed Tributary to Gilliam Creek AÇ AÅ M0 0.25 0.5 Miles Legend Open River/Creek Channel Piped River/Creek Channel Arterial Road Freeway Park Renton Tukwila Lake Local Road Exhibit 10. Surface Waterbodies in the Study Area The following sections describe each of these waterbodies starting with the I-405 southern project limit at the I-5 interchange and moving north. EXISTING CONDITIONS Renton Nickel Improvement Project Surface Water and Water Quality Discipline Report 23 Cottage Creek Cottage Creek is a tributary to Gilliam Creek that originates from the City Hall drainage basin located north of I-405 in the city of Tukwila. The creek flows south from the hillside and passes under Southcenter Boulevard via a culvert. The creek flows as an open channel for approximately 12 linear feet immediately north of I-405 then flows under I-405 via another culvert and confluences with Gilliam Creek at a stormwater outfall. Gilliam Creek Gilliam Creek flows along the south side of I-405 to the Green River in a series of open channels and large culverts. An unnamed tributary flow into Gilliam Creek, in addition to Cottage Creek at milepost 0.4. Gilliam Creek enters the Green River via a 108-inch- diameter flap gate. The flap gate prevents high flows in the Green River from entering the creek. Unnamed Tributary to Gilliam Creek An unnamed tributary flows into Gilliam Creek via a culvert immediately west of Gilliam Creek’s confluence with the Green River. There is no open channel associated with this tributary except for an approximately 50 foot section that daylights into, and flows through, a small riparian wetland immediately north of I-405. Green River The Green River drainage basin covers approximately 492 square miles. The Green River crosses I-405 at milepost 0.8. The river has an average flow of 1,696 cubic feet per second (cfs) based on flow records over the past 67 years as measured near Auburn. The Howard Hansen Dam, located northeast of Enumclaw at river mile 64.5, regulates the flow of the Green River. This regulation maintains the river’s flow at a 2- year, 24-hour peak flow rate. The Green River Valley is the historic floodplain of the Green River. The valley is relatively flat, and it has become highly urbanized with commercial and industrial development. The Land Use Patterns Discipline Report provides more information on land use in this area. This flap gate prevents high flows in the Green River from entering Gilliam Creek EXISTING CONDITIONS Renton Nickel Improvement Project 24 Surface Water and Water Quality Discipline Report Springbrook Creek Springbrook Creek is the main tributary to the Green River in the study area, and it crosses I-405 through a concrete box culvert at milepost 1.6. A side channel west of the creek parallels the main channel. A bridge over the side channel allows additional flow under I-405. Approximately one mile north of I-405, the Black River pump station was built at the mouth of Springbrook Creek. Flows from Springbrook Creek into the Green River are controlled by this pump station. Panther Creek and Wetlands Panther Creek originates from Panther Lake on hills east of SR 167 and is a tributary of Springbrook Creek. On the east side of SR 167, the creek splits into two channels. The east fork flows through the large Panther Creek wetland complex then crosses SR 167 near SW 23rd Street where it flows west into Springbrook Creek. The Panther Creek wetland complex extends from near SW 41st Street to the I-405/SR 167 interchange. At one time, the Panther Creek wetland complex drained to the west across SR 167 through a series of culverts. Most of these have since been plugged and the majority of flow has been redirected to a culvert crossing that was designed to promote fish passage. The west fork of the creek flows underneath SR 167 via two culverts near SW 34th Street. One of these culverts carries the main flow and the other provides overflow during high flows. From SR 167, Panther Creek flows west to Springbrook Creek. Rolling Hills Creek Rolling Hills Creek originates on the hills above Talbot Road on the south side of I-405 and is a tributary of Springbrook Creek. At South 15th Street, the creek flows from its natural ravine into a piped system that crosses I-405 at the Talbot Road overpass at milepost 2.8. From here, flows move west through a series of pipes, finally daylighting in an open channel at milepost 2.4. From this point, the creek flows through another series of culverts to the I-405/SR 167 interchange, and then it daylights again into the north end of the Panther Creek wetlands. Rolling Hills Creek flows south along SR 167, and crosses the highway in a box culvert. From here, the creek is Springbrook Creek near I-405 Rolling Hills Creek and overflow culvert at the SR 167/ I-405 interchange EXISTING CONDITIONS Renton Nickel Improvement Project Surface Water and Water Quality Discipline Report 25 piped south along the East Valley Road and then west along SW 19th Street to Springbrook Creek. Unnamed Tributary to Rolling Hills Creek An unnamed tributary to Rolling Hills Creek flows southerly from the hillside south of I-405, between Talbot Road S and Benson Road S, to a culvert under I-405. This channel is likely the historic main channel of Rolling Hills Creek. The unnamed tributary daylights on the north side of I-405 behind the One Renton Place building and flows westerly to where it confluences with Rolling Hills Creek between the parking lot associated with the Renton Cinema 8 and I-405. Thunder Creek Thunder Creek also originates on the hills above I-405 just northeast of Rolling Hills Creek and is a tributary of Springbrook Creek. Thunder Creek crosses I-405 at milepost 3.05 in a 48-inch-diameter culvert. At this point, the creek joins the flow from a historic coalmine. The foundation from the hoist used in the mining operation is still preserved next to the highway. Drainage from these two culverts enters a concrete flume that flows southwest to Talbot Road. From here, the flows are piped and discharged to Rolling Hills Creek. Cedar River The Cedar River crosses I-405 near the north end of the project at milepost 3.7. The flows from the Cedar River drain its 166 square mile basin and provide half of the total annual flow into Lake Washington. Direct stormwater discharges into the Cedar River are exempted from flow control provisions in the Highway Runoff Manual. What is the quality of surface waterbodies in the study area? Ecology prepares a 303(d) list every two years. This list summarizes those waterbodies that do not meet the state water quality standards and the reasons why the waterbodies do not comply with the standards. The extent of 303(d) listings in a watershed is mostly Thunder Creek and coal mine drainage in concrete flume upstream of the confluence with Rolling Hills Creek What is a concrete flume? A concrete flume is an open channel constructed of concrete designed to carry water. EXISTING CONDITIONS Renton Nickel Improvement Project 26 Surface Water and Water Quality Discipline Report dependent on the number and spacing of monitoring stations. According to the 303(d) list Ecology published in 2004, three waterbodies within the study area do not meet the state water quality standards Ecology lists parts of the Green River for not meeting water quality standards for dissolved oxygen, fecal coliform bacteria, and temperature. In the study area the Green River is 303(d) listed for fecal coliform bacteria and temperature. Springbrook Creek is also listed for not complying with standards for dissolved oxygen and fecal coliform bacteria. The Cedar River is listed for fecal coliform bacteria down stream of the study area. Some historical pollutant sources to rivers in the study area have already been eliminated. In 1982, a National Pollution Discharge Elimination System (NPDES) permit was issued to move the outfall of the South Wastewater Treatment Plant from the Green River to Puget Sound. This project was completed in early 1987. Prior to moving the outfall, the treatment plant was a major source of pollution in the Green River causing increased temperature, low dissolved oxygen, and ammonia toxicity. In 1992, the U.S. Environmental Protection Agency (EPA) approved a TMDL issued by Ecology. The Green River TMDL sets the allowable discharge of ammonia-nitrogen at zero pounds per day. No other TMDLs have been developed for the waterbodies in the study area at this time. However, as stated in the 2004 303(d) list, Ecology anticipates preparing TMDLs for both the Cedar River and Springbrook Creek in the future. Currently, King County is undertaking a major study called the Green-Duwamish Watershed Water Quality Assessment. As its goal, the water quality assessment will develop tools to analyze current and future water quality issues, to assist with salmon recovery planning, to guide stormwater management decisions, and to provide guidance for Ecology’s TMDL program. As mentioned previously, Thunder Creek joins drainage from a historic coalmine at milepost 3.05. The field investigators noted a strong sulfur smell coming from the coal mine flows, but no water quality data are available for this waterbody at this time. Because the City of Renton extracts its drinking water from a series of wells in an unconfined alluvial aquifer (Cedar River delta deposits), groundwater is a What is NPDES? The National Pollutant Discharge Elimination System (NPDES) permit program was established under Section 402 of the CWA, which prohibits the unauthorized discharge of pollutants from a point source (pipe, ditch, well, etc.) to U.S. waters, including municipal, commercial, and industrial wastewater discharges and discharges from large animal feeding operations. Permittees must verify compliance with permit requirements by monitoring their effluent, maintaining records, and filing periodic reports. EXISTING CONDITIONS Renton Nickel Improvement Project Surface Water and Water Quality Discipline Report 27 particularly important and highly regulated resource. The City has identified a Groundwater Protection Area near the north end of the study area to better protect the aquifer. The Geology, Soils, and Groundwater Discipline Report provides details on the aquifer and groundwater systems. How does urbanization affect surface water? Urbanization of natural landscapes radically alters natural drainage processes. In a forested landscape, vegetation, forest duff, and the upper soil layers capture the vast majority of rain and slowly release the rainwater into the ground. The prolific vegetation in forests draws some of water out of the ground and releases it back into the air. Water that remains in the ground is pulled by gravity downhill toward streams providing base flow to streams or recharge for groundwater. When impervious surfaces such as roofs, driveways, sidewalks, parking lots, compacted lawns, and streets replace the soils and vegetation much less water soaks into the ground, these surfaces decrease the amount of water available to recharge the groundwater and contribute to stream base flows. Also, the increased impervious surface generates more stormwater, which runs off much more quickly resulting in more streambank erosion, sedimentation, and downstream flooding. Stormwater runoff in urban areas also carries more pollutants, including: sediment from erosion; oil and grease from roads and parking lots; metals from tires, brakes and roofs; and pesticides, herbicides, and fertilizers from lawns and landscaping. Some of these pollutants dissolve in stormwater, but most become attached to small particles suspended in the water. Traffic on I-405 and SR 167 produces several specific types of pollutants in stormwater runoff. These include metals such as copper, zinc, and cadmium; oil and grease; sediment from tire and brake wear; and dirt washed off of vehicles during storms. This runoff tends to reduce the habitat value of streams physically changing the stream bed, due to the hydrologic effects as discussed above, and by degrading water quality. For example, the increased sediment in runoff affects water quality by reducing visibility, referred to as turbidity, and by depositing layers of sediment in the streams, referred to as sedimentation. Turbidity can harm fish and aquatic EXISTING CONDITIONS Renton Nickel Improvement Project 28 Surface Water and Water Quality Discipline Report insects. Removing the particles that cause turbidity is the primary strategy of many stormwater treatment systems. Another example is the nutrients in surface waters, such as those from fertilizers or pet waste, can lower the amount of dissolved oxygen available to aquatic life. These particular pollutants are of lesser concern on roadway projects as traffic-related uses do not generate substantial amounts of these nutrients. How is stormwater managed in the study area? A variety of facilities such as wetponds, biofiltration swales, ecology embankments, filter strips, and constructed wetlands currently treat stormwater along the project corridor. However, large portions of the highway do not have detention or water quality treatment for runoff because these facilities were not required when I-405 was originally built. Over the years, detention standards used to regulate stormwater flows have changed to require more stringent protocols. The newest design protocols for detention ponds require matching the project’s stormwater flow and duration characteristics to a selected predevelopment condition. For this project, the duration and magnitude of stormwater discharge into the streams and creeks would be generally equal to or less than that experienced under the existing conditions for the full range of design storm event, from 50 percent of the 2-year through the 50-year recurrent storm events. The Highway Runoff Manual (HRM) will be used as the design standard for this project and reflects the best available science in stormwater management to ensure that WSDOT projects adequately protect the functions and values of critical environmental areas including wetlands, streams, lakes, and marine waters. The HRM criteria were developed to protect receiving waters from adverse hydrologic changes and water quality degradation. This manual also provides guidance to support WSDOT in complying with ESA requirements. WSDOT maintains this manual to include all known, available, and reasonable methods of prevention and treatment for stormwater runoff discharges consistent with state and federal law. What is a 2-year or 50-year storm? This terminology is used to indicate the probably that a storm of a certain magnitude will occur in any particular year. For example, a 2-year storm is a storm that has a 50 percent chance of occurring in any single year, a 10-year storm has a 10 percent chance of occurring in a particular year, and a 50- year storm has a 2 percent chance of occurring in a year. Stormwater pond near I-405 EXISTING CONDITIONS Renton Nickel Improvement Project Surface Water and Water Quality Discipline Report 29 Stormwater ponds Stormwater ponds are designed to detain and slow down the release of stormwater into the drainage system to reduce flooding and erosion. The use of wetpools within stormwater ponds allows some water to be held for extended periods which provides time for suspended solids to settle out, thus allowing sediments to be removed efficiently from stormwater. The ponds for this project, however, will not include the usual permanent wetpool in the design because there are concerns about introducing new areas of standing water in the vicinity of the Renton Municipal Airport. Standing water can attract waterfowl and that can be a safety hazard to air traffic. The FAA, USDA, and Renton airport manager are being consulted to minimize air traffic safety issues associated with the design of facilities within the City of Renton limits along the I-405 corridor. For the Renton Nickel Improvement Project the function served by wetpools will be replaced with ecology embankment BMPs. Currently, stormwater ponds are located in the I-405/I-5 interchange at milepost 0.1 and at the SR 167/ I-405 interchange at milepost 2.3. Small ponds are also located west of SR 167 near SW 23rd Street and south of SW 41st Street. At the northern end of the project, ponds are located at mileposts 3.6 and 3.95. These ponds treat stormwater prior to discharge into the Cedar River. These concrete-lined ponds also serve as spill containment ponds in case hazardous materials are spilled on I-405 and washed into the storm drainage system thereby helping to protect the City of Renton’s drinking water aquifer. Biofiltration swales Biofiltration swales consist of broad, shallow grassy channels that are typically 200 feet long and designed so that stormwater that filters through it. The vegetation and soil matrix filters and absorbs pollutants from stormwater runoff providing water quality treatment. Treatment efficiency is relatively low; biofiltration swales are designed to remove 80 percent of the total suspended solids, but typically remove around 20 to 40 percent of pollutants from stormwater. The project team identified existing biofiltration swales south of I-405 at mileposts 0.95 and 1.55 and north of I-405 at milepost 1.0. The loop Stormwater pond near the I-405/SR 167 interchange Biofiltration swales filter stormwater runoff from highways prior to discharging runoff into the drainage system EXISTING CONDITIONS Renton Nickel Improvement Project 30 Surface Water and Water Quality Discipline Report ramps with SR 167 on the north side of I-405 also have biofiltration swales. Ecology embankments Ecology embankments are constructed as a continuous system placed along the highway shoulder that is filled with a granular material designed to remove pollutants. Stormwater flows off the highway and into the ecology embankment where it percolates through the media and pollutants are filtered out. The treated water is then collected by pipes and conveyed off site. Ecology embankments are very efficient at improving water quality and remove around 90 percent of most pollutants. These BMPs are typically used as the first step management system that then conveys stormwater to detention ponds for flow control. Exhibits 1-8, in the Introduction, show where ecology embankments will be built for this project. Ecology embankments are already in use in the project are along the west side of SR 167. Stormwater treatment wetlands Stormwater treatment wetlands can be designed to provide water quality treatment. These wetlands remove total suspended solids and associated pollutants by filtering, which enhances overall water quality. The vegetation in these wetlands provide additional stormwater treatment through biological uptake of nutrients and adsorption of other pollutants. How do environmental regulations affect the stormwater system design for this project? Water quality regulations mandated by the federal Clean Water Act (CWA) prohibit the discharge of pollutants from non-permitted sources. In Washington, authority for implementing the CWA is delegated to Ecology and the U.S. Army Corps of Engineers (Corps). The listing of salmonids under the Endangered Species Act (ESA) has triggered new requirements to protect salmon habitat and water quality. These requirements also focus on more coordination among permit agencies. What is an Ecology Embankment? Ecology embankments consist of a trench that is dug along side the highway shoulder, lain with perforated pipe, and backfilled with a filtration media. Water from the road flows into the ditch, is filtered by the media, and carried off site by the pipe. EXISTING CONDITIONS Renton Nickel Improvement Project Surface Water and Water Quality Discipline Report 31 WSDOT will need to obtain a variety of permits to construct the project. The best way to apply for all of these permits is by using the Joint Aquatic Resource Permit Application (JARPA). A JARPA allows an applicant to prepare a single application to apply for multiple water resource related permits issued by various agencies. The Hydraulic Project Approval (HPA) will contain a list of measures that the project will need to meet for any work within the high water mark of streams and drainages. The measures focus on protecting streams from construction-related impacts and pollutants. The HPA will include seasonal limits on construction activities, based on fish use, in which any work within a stream must be completed. The 401 certification, included in the JARPA, will verify that this project complies with state water quality standards and other aquatic resource protection. WSDOT uses its Highway Runoff Manual (HRM), certified as functionally equivalent to the SMMWW, to design stormwater facilities for transportation. To meet water quality standards, the manual requires treating stormwater runoff from new pollution- generating impervious surfaces (e.g., roads) before discharge. Stormwater runoff must also have flow controls (detention) in most situations to protect the receiving water from increases in flooding and streambank erosion. WSDOT will construct stormwater facilities based on the HRM to provide treatment and detention for all new impervious surfaces created by the project. FAA regulations require airports to evaluate wildlife hazards. The introduction of facilities that could increase the bird populations within 10,000 feet of the airport are reviewed by airport personnel. For this project, the stormwater plan was reviewed by both the City of Renton and the FAA because of the introduction of stormwater ponds that could have open water and encourage wildlife. It was determined that stormwater facilities for this project will not be a concern for the Renton Municipal Airport. For information on the protection of aquifers, refer to the Renton Nickel Improvement Project Soils, Geology, and Groundwater Discipline Report. What permits does the JARPA cover? The JARPA application covers several permits including: • the Hydraulic Project Approval (HPA) from Washington State Department of Fish and Wildlife • the 401 Water Quality Certification from Ecology • the Aquatic Resources Use Authorization Notification from the Washington State Department of Natural Resources • the Section 404 and Section 10 from the Corps • the Bridge Act Permit and Private Aids to Navigation (PATON – for non- bridge projects) from the Coast Guard. The Renton Nickel Improvement Project may not require all of these permits. Renton Nickel Improvement Project 32 Surface Water and Water Quality Discipline Report POTENTIAL EFFECTS What methods were used to evaluate effects on surface waterbodies and water quality? The I-405 team used the methods described in WSDOT’s Environmental Procedures Manual to evaluate the project’s effects on surface water and water quality during construction and during operation. The manual provides guidance that WSDOT follows to ensure that its projects comply with local, state, and federal laws and regulations. To determine operational effects, the team compared existing conditions with the proposed I-405 widening to determine the new impervious pavement distribution and the affected surface waterbodies. Next, the team estimated the annual loading of pollution (total suspended solids [TSS], phosphorus, and zinc) in stormwater runoff from each of the study area’s three basins. Pollutant loading was calculated for the threshold discharge areas (TDAs), which were established by the engineering team as the area that will contribute runoff from the project. The TDAs for this project occupy a total area of 225.76 acres and are shown in Exhibit 11. The team calculated pollutant loads using “Method 2: Simple Method” from WSDOT's Environmental Procedures Manual. This method is based on data trends from the National Urban Runoff Pollutant database. Typical concentrations of pollutants in runoff were determined based on the average daily traffic volume expected to use the highway. Printouts of the spreadsheets for this calculation are provided in Appendix A. What is a threshold discharge area? Threshold discharge areas (TDAs) are areas of the project that drain to a single natural discharge location or multiple discharge locations that combine within one-quarter mile downstream. The Renton Nickel Improvement Project has five TDAs: one in the Green River Basin, three in the Springbrook Creek Basin, and one in the Cedar River Basin. What are total suspended solids (TSS)? TSS are soil particles carried in moving water. High levels of TSS can make a stream or lake appear muddy or cloudy and can affect fish by clogging gills and reducing their ability to see and forage for food. POTENTIAL EFFECTS Renton Nickel Improvement Project Surface Water and Water Quality Discipline Report 33 Black River Riparian Forest Fort Dent Park Cedar River Park Liberty Park SW 41st St S W 3 4 t h S t S W 2 7 t h S t SW 16th St Southcenter ParkwayW Valley HwyI n t e r u r ban Ave SMa pl e V alle y H w yRainier Ave SS W Suns e t B lvdS W 7 t h S t S W G r a d y W a y Lind Ave SWTUKWILA RENTON I-405 Northern Project Limit at SR 169 I-405 Southern Project Limit at I-5 SR 167 Southern Project Limit at SW 41st St Benson Rd SSW 23rd St Talbot Rd SBenson Dr SAæ Aç !"`$ Aí %&e( Ginger Creek Rolling Hills Creek Panther Creek Gilliam Creek Mill Creek Green River Springbrook Creek Cedar River Panther Creek Wetlands Thunder Hills Creek Cottage Creek TDA-S1 TDA-G1 TDA-S2 TDA-C1 TDA-S3 Legend Local Road Arterial Road Freeway Open River/Creek Channel Piped River/Creek Channel TDA-C1 Boundary TDA-G1 Boundary TDA-S1 Boundary TDA-S2 Boundary TDA-S3 Boundary Park Renton Tukwila Lake M0 0.25 0.5 Miles Exhibit 11: Threshold Discharge Areas Will project construction temporarily affect surface waterbodies and water quality? During construction, work crews clear, grade, and prepare the site for new pavement. Constructing this new pavement area exposes bare soil that is easily eroded by rainfall and water runoff, which can create short-term effects to water quality. These effects to water quality are minimized by using required erosion control measures that are commonly referred to as best management practices (BMPs). Standard construction BMPs are used to minimize erosion and soil movement so that erosion from construction sites does not contribute solids and adsorbed pollutants to POTENTIAL EFFECTS Renton Nickel Improvement Project 34 Surface Water and Water Quality Discipline Report nearby receiving waters. BMPs are required on all roadway construction projects including the I-405 Renton Nickel Improvement Project and will be described in more detail in the Temporary Erosion and Sediment Control (TESC) plan that will be written by WSDOT prior to beginning construction. The BMPs used for this project will be either sediment controls or erosion controls BMPs or a combination of both. Sediment control BMPs physically trap runoff until most contaminants settle out or are filtered through the underlying soils. The basic mechanisms for pollutant removal are gravity settling, infiltration of soluble nutrients through soil or filters, or biological and chemical processes. Erosion control BMPs are source control practices such as street sweeping, maintaining vegetated buffers, and limiting actual construction to dry periods when possible. BMPs such as these prevent loose soil from leaving the construction site and reaching local waterbodies and keeps effects at an insignificant level. The existing highway has some BMPs already in place. The existing ecology embankment along the west side of SR 167 will be replaced by new facilities as part of this project. During construction of the new roadway and new ecology embankments, the old ecology embankments will be removed. WSDOT will use construction BMPs to maintain water quality during construction periods when permanent BMPs may not be functional. Construction can also create the potential for unexpected spills of hazardous materials used during the construction process. Construction work typically uses hazardous or toxic materials such as fuel, oil, paint, and other potentially toxic liquids, which may be temporarily stored on site. These materials present the greatest risk near open waterbodies such as where streams and rivers pass under the highway. To prevent unexpected spills of hazardous materials to waterbodies, a Spill Prevention, Control, and Countermeasures (SPCC) Plan will be prepared before construction starts. Along with the TESC plan, the measures provided will prevent any substantial effects on water quality during construction. Where there is work over open water, such as at the new southbound and northbound bridges over Springbrook Creek and Oakesdale Avenue, spills of concrete are a concern because concrete can raise the ph of waterbodies and harm fish. WSDOT will What are best management practices? Best management practices, referred to commonly as BMPs, are methods used to minimize or avoid effects to water quality such as sediment getting into streams, during construction. Examples of BMPs include installing filter fabric fence downstream of all exposed slopes, around existing drainage inlets, and along river, stream, and drainage channels near work areas to prevent sediment-laden stormwater from entering streams. POTENTIAL EFFECTS Renton Nickel Improvement Project Surface Water and Water Quality Discipline Report 35 protect receiving waters from concrete spills and production runoff. Will the project permanently affect surface waterbodies and water quality? Concrete and Asphalt typically have higher stormwater runoff volumes and velocities than most other land covers because these surfaces are highly impervious, and therefore prevent infiltration and reduce evaporation. This project will add approximately 15 acres of new impervious surface area to the highway. The five Threshold Discharge Areas (TDAs) within the study area currently have 115 acres of impervious surface collectively. This results in almost 13 percent more impervious surface within the project limits. The added impervious surface will cover areas that are currently pervious areas. The roadside areas that will be paved are generally landscaped with grass and some shrubs. Highway runoff contains several pollutants of concern that occur as solids: nutrients such as phosphorous, which is generally bonded to dirt particles; heavy metals such as lead, copper, and zinc; and petroleum hydrocarbons. These contaminates accumulate on the road surface and are eventually washed away by rainfall. Runoff from areas equivalent in size to the new impervious area that is added by this project will be mitigated for both quality and flow control. Since the increase of impervious surface within the TDAs will be less than 50 percent, full retrofit of stormwater treatment is not required. Full retrofit treatment will be investigated as part of later stages of the I-405 Corridor Program. Stormwater detention Stormwater detention facilities will be built as part of this project to control stormwater discharge from areas equivalent to new impervious surfaces only. No retrofit treatment is proposed for existing impervious surfaces. Exhibit 12 summarizes these facilities and Exhibit 13 shows the locations of these facilities. How does runoff from a forest area compare with a highway? For a forested area in King County approximately 55 percent of the rain that falls each year eventually appears as water in a stream. The remainder of the rainwater either percolates into the soil or is evaporated back into the atmosphere. However, for a highly impervious area, approximately 85 to 90 percent of annual rainfall eventually appears as water in a stream and the remaining water replenishes either the groundwater or the atmosphere. Source: King County Surface Water Design Manual 2005. POTENTIAL EFFECTS Renton Nickel Improvement Project 36 Surface Water and Water Quality Discipline Report Exhibit 12. Stormwater Flow Control Facilities Facility ID1 Receiving Water Facility Type New Impervious Area (acres) Contributing Area2 (acres) G1.1 Green River Pond 1.11 G1.2 Green River Pond 1.05 .97 S1.1 Springbrook Creek Pond 6.32 6.45 S2.2 Springbrook Creek Pond 3.26 3.71 S3.1 Springbrook Creek Combined Stormwater Treatment Wetland and Detention Facility 2.31 2.82 1. The Facility ID numbers correspond to the numbers shown on Exhibit 13 with the exception of C1.1, which does not represent an actual facility. 2. Contributing Area is the amount of impervious surface that delivers runoff to a particular stormwater detention facility Black River Riparian Forest Fort Dent Park Cedar River Park Liberty Park SW 41st St S W 3 4 t h S t S W 2 7 t h S tSouthcenter ParkwayW Valley HwyI n t e r u r ban Ave SMa p le V alley H w yRainier Ave SS W Sun s e t B lvdS W 7 t h S t S W G r a d y W a y Lind Ave SWTUKWILA RENTON I-405 Northern Project Limit at SR 169 I-405 Southern Project Limit at I-5 SR 167 Southern Project Limit at SW 41st St Benson Rd SSW 23rd St Talbot Rd SBenson Dr SAæ Aç !"`$ Aí %&e( SW 16th St G1.1 G1.2 S1.1 S2.2 S3.1 M0 0.25 0.5 Miles Facility NumberS 3.1 Legend Arterial Road Freeway Park Renton Tukwila Lake Open River/Creek Channel Piped River/Creek Channel Stormwater Flow Control Facility Local Road POTENTIAL EFFECTS Renton Nickel Improvement Project Surface Water and Water Quality Discipline Report 37 Exhibit 13. Stormwater Flow Control Facility Locations Water quality treatment The Renton Nickel Improvement Project will provide enhanced water quality treatment of equivalent areas for all new freeway mainline pavement where the projected average daily traffic demands exceed 30,000. This level of water quality treatment will be facilitated using ecology embankments, biofiltration swales, and stormwater treatment wetlands in accordance with the WSDOT HRM. These types of BMPs are described in the Existing Conditions section of this report and shown on Exhibits 2 through 9 in the Introduction. Exhibit 14 shows pollutant removal efficiencies for the types of stormwater treatment facilities that will be used on this project. Exhibit 14. Pollutant Removal Efficiencies for Treatment Facilities Percent Pollutant Removal Treatment Facility Suspended Solids Total Phosphorus Total Nitrogen Trace Metals Notes Ecology Embankments (July 24, 2003 WSDOT conditional use designation memorandum) 88-94 59-89 n/a 84-96 (zinc) Stormwater Treatment Wetlands (September 2004 Environmental Procedures Manual) 80-100 60-80 40-60 60-80 Efficiency depends on residence time n/a – not available Pollutant loading for both the Build and No Build alternatives are shown in Exhibit 15. The numbers for the Build Alternative assume that the new impervious area will be addressed using BMPs described in this report and designed to specifications in the Highway Runoff Manual. For the No Build Alternative, the numbers show pollutant loading assuming that no new impervious area would be added. The Build and No Build alternatives have very similar pollutant loadings. This indicates that the project will not significantly change the existing water quality conditions in the study area. What is meant by pollutant loading? Pollutant loading is a term used to refer to the amount of a pollutant that enters a waterbody in a specified amount of time. Estimates of pollutant loads are usually given in pounds per year. POTENTIAL EFFECTS Renton Nickel Improvement Project 38 Surface Water and Water Quality Discipline Report Exhibit 15. Pollutant Loadings for Build and No Build Alternatives in lbs/year Green River 0 5 10 15 20 TSS (1,000 lbs) TP Total Zinc Dissolved ZincPollutant Loading in PoundsBuild No build Springbrook Creek 0 5 10 15 20 TSS (1,000 lbs) TP Total Zinc Dissolved ZincPollutant Loading in PoundsBuild No build Cedar River 0 5 10 15 20 TSS (1,000 lbs) TP Total Zinc Dissolved ZincPollutant Loading in PoundsBuild No build POTENTIAL EFFECTS Renton Nickel Improvement Project Surface Water and Water Quality Discipline Report 39 This project will not affect any of the three 303(d) listed waterbodies in this area: The Green River is 303(d) listed for dissolved oxygen, fecal coliform bacteria, and temperature. None of these parameters will be affected by runoff from this project. Springbrook Creek is 303(d) listed for dissolved oxygen and fecal coliform bacteria. None of these parameters will be affected by runoff from this project. The Cedar River is also listed on the state’s 303(d) list, but only for fecal coliform bacteria and temperature. None of these parameters will be affected by runoff from this project Temperature in local waterbodies is a seasonal concern and can be influenced by lakes and open- water ponds1. Open-water ponds such as detention ponds with wetpools allow runoff to be exposed to the sun and warm up a few degrees. However, the ponds for this project are small relative to the flow of the rivers to which they will discharge and they will not have wetpools. The ponds from this project will be dry during the summer when river temperatures are highest. Because of the high degree of statistical variability associated with fecal coliform bacteria in highway runoff, reliable data for this constituent are not currently available. However, fecal coliform bacteria are typically not considered a significant concern in runoff from highways and so it is not expected that this project will affect the existing fecal coliform issue in any of these waterbodies. Zinc is a constituent on the 303(d) list that is a primary concern for highway runoff. Zinc can be efficiently removed from highway runoff using ecology embankments or other “enhanced” BMPs. Loading calculations shown in Exhibit 15 indicate that input of zinc to these impaired waterbodies will not change. 1 Regional, Synchronous Field Determination of Summertime Stream Temperature in Western Washington. The Washington Water Resource: quarterly report of the Center for Urban Water Resources Management. Derek B. Booth. 2002. POTENTIAL EFFECTS Renton Nickel Improvement Project 40 Surface Water and Water Quality Discipline Report Will the project have indirect effects on surface waterbodies and water quality? Indirect effects typically associated with road projects are changes in land use that happen because accessibility to local areas becomes improved. The Renton and Tukwila areas are already very highly urbanized and it is not expected that this project will significantly affect land use in the study area. Therefore, no indirect effects to surface waters are expected because of this project. What are indirect effects? Indirect effects are defined in the WSDOT Environmental Procedures Manual as the “effect caused by the proposed action that is later in time or farther removed in distance, but still reasonably foreseeable. Indirect effects may include growth-inducing effects and other effects related to induced changes in the pattern of land use, population density or growth rate, and related effects on air and water and other natural systems, including ecosystems.” Were cumulative effects looked at for this discipline? The team did not evaluate cumulative effects for this discipline report. A report of cumulative effects is not needed for every discipline studied for NEPA and SEPA documentation. The disciplines that were studied for cumulative effects are Air Quality, Surface Water and Water Quality, Fisheries and Aquatic Resources, and Wetlands. The cumulative effects for these disciplines are presented in the Cumulative Effects Analysis Discipline Report. Renton Nickel Improvement Project Surface Water and Water Quality Discipline Report 41 MEASURES TO AVOID OR MINIMIZE PROJECT EFFECTS How will the project avoid or reduce negative effects to surface water during construction? The primary means of avoiding and reducing potential effects from this project are to use standard BMPs during construction. Specifically, the I-405 Corridor Program NEPA/SEPA Final Environmental Impact Statement makes these commitments to protect water quality during construction of I-405 projects: For projects constructed within 300 feet of a lake or stream, or where concentrated construction site discharge may flow directly to surface waters, all site grading and initial stabilization could be scheduled to occur only during the dry season, May 1 through September 30. Where construction must occur within stream channels, such construction will occur “in the dry” whereby stream flow is temporarily diverted around the work site where practicable to prevent turbidity. If other construction activities occur during the wet season, such as subgrade or pavement installation, utilities placement, or curbs and sidewalks, a plan will be developed that: 1) Limits disturbed area activities to a maximum of 48 hours at any single location, and includes provisions for temporarily ceasing construction and quickly stabilizing the site when rainfall greater than one-half inch in a 12- hour period is measured at the site. 2) Uses alternative means to treat construction site runoff such as overland flow across a vegetated surface, uses of coagulants in the sediment ponds or other stormwater chemical treatment measures, or uses polymer soil stabilizers to reduce erosion. If coagulants are used, then a nontoxic compound will be used as approved by WSDOT. Construction disturbances will be limited to the minimum area needed, the shortest duration, and an appropriate distance away from MEASURES TO AVOID OR MINIMIZE PROJECT EFFECTS Renton Nickel Improvement Project 42 Surface Water and Water Quality Discipline Report waterbodies as practical. Seasonal work windows will be identified and implemented. BMPs such as fencing, landscaping, erosion matting, hydro mulching, soil imprinting, straw bales, detention/sediment trap basins, and vegetated fringes as described in the HRM will be used as appropriate. Construction disturbance will be limited to the smallest feasible area. Natural undisturbed areas would be avoided and disturbed as little as possible. Clearing activities will be staged such that construction areas are cleared no earlier than one week ahead of starting construction where practicable. If this is impractical, then cleared areas will be immediately mulched, covered with plastic, or otherwise stabilized. Construction mitigation measures will be implemented to reduce the use, transfer, and storage of hazardous materials in sensitive areas. How will the project avoid or reduce negative effects to surface water during operation? WSDOT has designed stormwater facilities for this project that will both maintain the rate of stormwater runoff at existing conditions and remove pollutants from runoff generated by the project. With these facilities, the runoff is expected to meet Washington State water quality standards listed in WAC173- 201(A). Renton Nickel Improvement Project Surface Water and Water Quality Discipline Report 43 REFERENCES Published Documents Booth, Derek B. 2002 Regional, Synchronous Field Determination of Summertime Stream Temperature in Western Washington. The Washington Water Resource: quarterly report of the Center for Urban Water Resources Management. King County Department of Natural Resources and Parks, Water and Land Resources Division. 2005 King County Surface Water Design Manual. Washington Administrative Code (WAC) 2003 State Water Quality Standards, Title 173, Chapter 173-201(A). Washington State Department of Ecology (Ecology) 2004 Stormwater Management Manual for Western Washington. Washington State Department of Transportation (WSDOT) 2004 Environmental Procedures Manual, Section 431. 2004 Highway Runoff Manual. 2002 I-405 Corridor Program, NEPA/SEPA Final Environmental Impact Statement. Websites TMDL webpage: http://www.ecy.wa.gov/programs/wq/tmdl/index.html. 303(d) webpage: http://www.ecy.wa.gov/programs/wq/303d/2002/2004_documents/wq_assessment_cats200 4.html. WRIA 08 webpage http://www.ecy.wa.gov/programs/eap/wrias/08.html. WRIA 09 webpage http://www.ecy.wa.gov/programs/eap/wrias/09.html. APPENDIX A Pollutant Loading Calculations Renton Nickel Improvement Project Surface Water and Water Quality Discipline Report A-1 C ALCULATION M ETHOD Water Quality was calculated using Method 2 in WSDOT’s Environmental Procedures Manual. Method 2 is known as the “Simple Method” because it relies on an empirical equation developed for use in estimating pollutant loads from urban watersheds. It is not necessarily specific to estimating road or highway pollutant loads, however, one of the categories of runoff assessed in its development was “National Urban Highway Runoff”, so the constants developed for this category are applicable to WSDOT analyses. The steps used in the Simple Method are as follows: Step 1 – Calculate runoff depth R = [(H x Pj x Rv)]/12] x A Where: R = Runoff depth (acre-feet) over the defined time interval H = Rainfall amount over time interval or for defined storm event (inches). (Use the average annual precipitation when calculating annual loads.) Pj = Percentage of storms over time interval that produce runoff Rv = Runoff Coefficient (Ratio of runoff to rainfall) = 0.05 + 0.009(I) 12 = Conversion factor (inches to feet) A = Drainage area (acres) I = Percent Impervious For this project, a conservative assumption of 0.9 was used for Pj and 35 inches was used for H. APPENDIX A Renton Nickel Improvement Project A-2 Surface Water and Water Quality Discipline Report Step 2 – Runoff depth converted to discharge Q = (R)(0.504) Where: Q = Discharge (ft3/sec/day) 0.504 = Conversion factor Step 3 – Calculate the pollutant load: L = (Q) (C) x 5.39 Where: L = Mass load over time interval (pounds) C = Flow-weighted mean concentration of the pollutant in the runoff (mg/L) 5.39 = Conversion factor Values for C were taken from an empirical table based on traffic volume in Average Daily Trips (ADT). APPENDIX A Renton Nickel Improvement Project Surface Water and Water Quality Discipline Report A-3 Renton Nickel Pollutant Load using the "Simple Method" Loading in Green River Basin under No Build conditions R= (HxPjxRv)/12x(A) 10 acre-ft/yr H= 35 annual precipitation (inches) Pj= 0.9 coefficient of storms producing runoff Rv= 0.054 runoff coefficient 37.72 existing pervious area 31.41 existing impervious 0 new impervious A= 69.13 TDA drainage area (acres) I= 45% existing percent impervious 45% project percent impervious 0% percent new impervious Q= R*0.504 = 5 ft3/sec/day L=Q*C*5.39 = mean conc (mg/l) Annual Load (pounds) Treatment Efficiency Post Treatment Load C tss = 123 3280 90% 3280 C phos = 0.33 9 75% 9 C zinc tot= 0.277 7 90% 7 C zinc dis= 0.127 3 90% 3 Note: Simple method is discussed in the 2003 Environmental Procedures Manual Assumes 151,000 ADT APPENDIX A Renton Nickel Improvement Project A-4 Surface Water and Water Quality Discipline Report Renton Nickel Pollutant Load using the "Simple Method" Loading in Green River Basin under Build conditions R= (HxPjxRv)/12x(A) 10 acre-ft/yr H= 35 annual precipitation (inches) Pj= 0.9 coefficient of storms producing runoff Rv= 0.054 runoff coefficient 37.72 existing pervious area 31.41 existing impervious 1.05 new impervious A= 69.13 TDA drainage area (acres) I= 45% existing percent impervious 47% project percent impervious 2% percent new impervious Q= R*0.504 = 5 ft3/sec/day L=Q*C*5.39 = mean conc (mg/l) Annual Load (pounds) Treatment Efficiency Post Treatment Load C tss = 128 3422 90% 3375 C phos = 0.33 9 75% 9 C zinc tot= 0.293 8 90% 8 C zinc dis= 0.136 4 90% 4 Note: Simple method is discussed in the 2003 Environmental Procedures Manual Assumes 162,000 ADT APPENDIX A Renton Nickel Improvement Project Surface Water and Water Quality Discipline Report A-5 Renton Nickel Pollutant Load using the "Simple Method" Loading in Springbrook Basin under No Build conditions R= (HxPjxRv)/12x(A) 19 acre-ft/yr H= 35 annual precipitation (inches) Pj= 0.9 coefficient of storms producing runoff Rv= 0.055 runoff coefficient 65.63 existing pervious area 65.9 existing impervious 0 new impervious A= 131.53 TDA drainage area (acres) I= 50% existing percent impervious 50% project percent impervious 0% percent new impervious Q= R*0.504 = 9 ft3/sec/day L=Q*C*5.39 = mean conc (mg/l) Annual Load (pounds) Treatment Efficiency Post Treatment Load C tss = 123 6289 90% 6289 C phos = 0.33 17 75% 17 C zinc tot= 0.277 14 90% 14 C zinc dis= 0.127 6 90% 6 Note: Simple method is discussed in the 2003 Environmental Procedures Manual Assumes 150,000 ADT APPENDIX A Renton Nickel Improvement Project A-6 Surface Water and Water Quality Discipline Report Renton Nickel Pollutant Load using the "Simple Method" Loading in Springbrook Basin under Build conditions R= (HxPjxRv)/12x(A) 19 acre-ft/yr H= 35 annual precipitation (inches) Pj= 0.9 coefficient of storms producing runoff Rv= 0.055 runoff coefficient 65.63 existing pervious area 65.9 existing impervious 12.98 new impervious A= 131.53 TDA drainage area (acres) I= 50% existing percent impervious 60% project percent impervious 10% percent new impervious Q= R*0.504 = 10 ft3/sec/day L=Q*C*5.39 = mean conc (mg/l) Annual Load (pounds) Treatment Efficiency Post Treatment Load C tss = 123 6391 90% 5823 C phos = 0.33 17 75% 16 C zinc tot= 0.277 14 90% 13 C zinc dis= 0.127 7 90% 6 Note: Simple method is discussed in the 2003 Environmental Procedures Manual Assumes 150,000 ADT APPENDIX A Renton Nickel Improvement Project Surface Water and Water Quality Discipline Report A-7 Renton Nickel Pollutant Load using the "Simple Method" Loading in Cedar River Basin under No Build conditions R= (HxPjxRv)/12x(A) 4 acre-ft/yr H= 35 annual precipitation (inches) Pj= 0.9 coefficient of storms producing runoff Rv= 0.055 runoff coefficient 13.4 existing pervious area 17.65 existing impervious 0 new impervious A= 31.05 TDA drainage area (acres) I= 57% existing percent impervious 57% project percent impervious 0% percent new impervious Q= R*0.504 = 2 ft3/sec/day L=Q*C*5.39 = mean conc (mg/l) Annual Load (pounds) Treatment Efficiency Post Treatment Load C tss = 121 1477 90% 1477 C phos = 0.34 4 75% 4 C zinc tot= 0.273 3 90% 3 C zinc dis= 0.125 2 90% 2 Note: Simple method is discussed in the 2003 Environmental Procedures Manual Assumes 147,000 ADT APPENDIX A Renton Nickel Improvement Project A-8 Surface Water and Water Quality Discipline Report Renton Nickel Pollutant Load using the "Simple Method" Loading in Cedar River Basin under Build conditions R= (HxPjxRv)/12x(A) 5 acre-ft/yr H= 35 annual precipitation (inches) Pj= 0.9 coefficient of storms producing runoff Rv= 0.055 runoff coefficient 13.4 existing pervious area 17.65 existing impervious 1.02 new impervious A= 31.05 TDA drainage area (acres) I= 57% existing percent impervious 60% project percent impervious 3% percent new impervious Q= R*0.504 = 2 ft3/sec/day L=Q*C*5.39 = mean conc (mg/l) Annual Load (pounds) Treatment Efficiency Post Treatment Load C tss = 127 1558 90% 1512 C phos = 0.33 4 75% 4 C zinc tot= 0.291 4 90% 3 C zinc dis= 0.135 2 90% 2 Note: Simple method is discussed in the 2003 Environmental Procedures Manual Assumes 160,000 ADT