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N A T I O N A L C O O P E R A T I V E H I G H W A Y R E S E A R C H P R O G R A M NCHRP REPORT 778 Bridge Stormwater Runoff Analysis and Treatment Options Scott Taylor Michael Baker international Carlsbad, CA Michael Barrett George Ward University of texas Austin, TX Marc Leisenring Geosyntec consUltants Portland, OR Marie Venner venner consUltinG Littleton, CO Roger Kilgore kilGore consUltinG and ManaGeMent Denver, CO Subscriber Categories Bridges and Other Structures ⢠Environment ⢠Hydraulics and Hydrology TRANSPORTAT ION RESEARCH BOARD WASHINGTON, D.C. 2014 www.TRB.org Research sponsored by the American Association of State Highway and Transportation Officials in cooperation with the Federal Highway Administration
NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM Systematic, well-designed research provides the most effective approach to the solution of many problems facing highway administrators and engineers. Often, highway problems are of local interest and can best be studied by highway departments individually or in cooperation with their state universities and others. However, the accelerating growth of highway transportation develops increasingly complex problems of wide interest to highway authorities. These problems are best studied through a coordinated program of cooperative research. In recognition of these needs, the highway administrators of the American Association of State Highway and Transportation Officials initiated in 1962 an objective national highway research program employing modern scientific techniques. This program is supported on a continuing basis by funds from participating member states of the Association and it receives the full cooperation and support of the Federal Highway Administration, United States Department of Transportation. The Transportation Research Board of the National Academies was requested by the Association to administer the research program because of the Boardâs recognized objectivity and understanding of modern research practices. The Board is uniquely suited for this purpose as it maintains an extensive committee structure from which authorities on any highway transportation subject may be drawn; it possesses avenues of communications and cooperation with federal, state and local governmental agencies, universities, and industry; its relationship to the National Research Council is an insurance of objectivity; it maintains a full-time research correlation staff of specialists in highway transportation matters to bring the findings of research directly to those who are in a position to use them. The program is developed on the basis of research needs identified by chief administrators of the highway and transportation departments and by committees of AASHTO. Each year, specific areas of research needs to be included in the program are proposed to the National Research Council and the Board by the American Association of State Highway and Transportation Officials. Research projects to fulfill these needs are defined by the Board, and qualified research agencies are selected from those that have submitted proposals. Administration and surveillance of research contracts are the responsibilities of the National Research Council and the Transportation Research Board. The needs for highway research are many, and the National Cooperative Highway Research Program can make significant contributions to the solution of highway transportation problems of mutual concern to many responsible groups. The program, however, is intended to complement rather than to substitute for or duplicate other highway research programs. Published reports of the NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM are available from: Transportation Research Board Business Office 500 Fifth Street, NW Washington, DC 20001 and can be ordered through the Internet at: http://www.national-academies.org/trb/bookstore Printed in the United States of America NCHRP REPORT 778 Project 25-42 ISSN 0077-5614 ISBN 978-0-309-28415-8 Library of Congress Control Number 2014941750 © 2014 National Academy of Sciences. All rights reserved. COPYRIGHT INFORMATION Authors herein are responsible for the authenticity of their materials and for obtaining written permissions from publishers or persons who own the copyright to any previously published or copyrighted material used herein. Cooperative Research Programs (CRP) grants permission to reproduce material in this publication for classroom and not-for-profit purposes. Permission is given with the understanding that none of the material will be used to imply TRB, AASHTO, FAA, FHWA, FMCSA, FTA, or Transit Development Corporation endorsement of a particular product, method, or practice. It is expected that those reproducing the material in this document for educational and not-for-profit uses will give appropriate acknowledgment of the source of any reprinted or reproduced material. For other uses of the material, request permission from CRP. NOTICE The project that is the subject of this report was a part of the National Cooperative Highway Research Program, conducted by the Transportation Research Board with the approval of the Governing Board of the National Research Council. The members of the technical panel selected to monitor this project and to review this report were chosen for their special competencies and with regard for appropriate balance. The report was reviewed by the technical panel and accepted for publication according to procedures established and overseen by the Transportation Research Board and approved by the Governing Board of the National Research Council. The opinions and conclusions expressed or implied in this report are those of the researchers who performed the research and are not necessarily those of the Transportation Research Board, the National Research Council, or the program sponsors. The Transportation Research Board of the National Academies, the National Research Council, and the sponsors of the National Cooperative Highway Research Program do not endorse products or manufacturers. Trade or manufacturersâ names appear herein solely because they are considered essential to the object of the report.
The National Academy of Sciences is a private, nonprofit, self-perpetuating society of distinguished scholars engaged in scientific and engineering research, dedicated to the furtherance of science and technology and to their use for the general welfare. On the authority of the charter granted to it by the Congress in 1863, the Academy has a mandate that requires it to advise the federal government on scientific and technical matters. Dr. Ralph J. Cicerone is president of the National Academy of Sciences. The National Academy of Engineering was established in 1964, under the charter of the National Academy of Sciences, as a parallel organization of outstanding engineers. It is autonomous in its administration and in the selection of its members, sharing with the National Academy of Sciences the responsibility for advising the federal government. The National Academy of Engineering also sponsors engineering programs aimed at meeting national needs, encourages education and research, and recognizes the superior achievements of engineers. Dr. C. D. Mote, Jr., is president of the National Academy of Engineering. The Institute of Medicine was established in 1970 by the National Academy of Sciences to secure the services of eminent members of appropriate professions in the examination of policy matters pertaining to the health of the public. The Institute acts under the responsibility given to the National Academy of Sciences by its congressional charter to be an adviser to the federal government and, on its own initiative, to identify issues of medical care, research, and education. Dr. Harvey V. Fineberg is president of the Institute of Medicine. The National Research Council was organized by the National Academy of Sciences in 1916 to associate the broad community of science and technology with the Academyâs purposes of furthering knowledge and advising the federal government. Functioning in accordance with general policies determined by the Academy, the Council has become the principal operating agency of both the National Academy of Sciences and the National Academy of Engineering in providing services to the government, the public, and the scientific and engineering communities. The Council is administered jointly by both Academies and the Institute of Medicine. Dr. Ralph J. Cicerone and Dr. C. D. Mote, Jr., are chair and vice chair, respectively, of the National Research Council. The Transportation Research Board is one of six major divisions of the National Research Council. The mission of the Transporta- tion Research Board is to provide leadership in transportation innovation and progress through research and information exchange, conducted within a setting that is objective, interdisciplinary, and multimodal. The Boardâs varied activities annually engage about 7,000 engineers, scientists, and other transportation researchers and practitioners from the public and private sectors and academia, all of whom contribute their expertise in the public interest. The program is supported by state transportation departments, federal agencies including the component administrations of the U.S. Department of Transportation, and other organizations and individu- als interested in the development of transportation. www.TRB.org www.national-academies.org
C O O P E R A T I V E R E S E A R C H P R O G R A M S AUTHOR ACKNOWLEDGMENTS This study was conducted with funding provided through NCHRP Project 25-42, Bridge Stormwater Runoff Analysis and Treatment Options. This document was prepared by Mr. Scott Taylor of RBF Con- sulting, and Dr. Michael Barrett and Dr. George Ward, University of Texas, Marc Leisenring, Geosyntec Consultants, Marie Venner, Venner Consulting and Roger Kilgore, Kilgore Consulting and Management. CRP STAFF FOR NCHRP REPORT 778 Christopher W. Jenks, Director, Cooperative Research Programs Christopher J. Hedges, Manager, National Cooperative Highway Research Program Andrew C. Lemer, Senior Program Officer Sheila A. Moore, Program Associate Eileen P. Delaney, Director of Publications Margaret B. Hagood, Editor NCHRP PROJECT 25-42 PANEL Field of Transportation PlanningâArea of Impact Analysis Matthew S. Lauffer, North Carolina DOT, Raleigh, NC (Chair) Le Chi Nguyen, Washington State DOT, Seattle, WA Thomas J. Grizzard, Jr., Virginia Polytechnic Institute and State University, Manassas, VA D. Keith Jones, California DOT, Davis, CA Jeffrey S. MacKay, NTM Engineering, Inc., Dillsburg, PA Alexander J. Murray, Massachusetts DOT, Boston, MA W. Wesley Peck, Tennessee DOT, Nashville, TN Chad R. Wagner, U.S. Geological Survey, Raleigh, NC Susan Jones, FHWA Liaison Stephen F. Maher, TRB Liaison
F O R E W O R D This report presents information and an analysis process for identifying strategies for man- agement of stormwater runoff from highway bridges. Departments of transportation (DOTs) and other public agencies responsible for managing stormwater runoff to reduce pollution loads in receiving waters may use this information and process to assist their selection of a cost-effective strategy for a particular bridge. The report will be helpful to designers and man- agers who must identify and assess the merits of stormwater management practices. While most bridge stormwater runoff discharges directly to the water bodies below, state DOTs and local agencies are increasingly being encouraged to provide treatment. Such requirements initially have been applied to the runoff from on-grade pavements, but col- lection and treatment or other mitigation strategies for bridge runoff management pose particular challenges. What may be judged to be best management practices (BMPs) for on-grade pavement have limited effectiveness when applied to bridges. Bridges account for a very small portion of the highway systemsâ runoff. Addressing increasingly stringent highway runoff regulatory requirements by applying on-grade runoff management practices to bridges is not only costly but may compromise worker and road- user safety with limited benefits to water quality. The objective of NCHRP Project 25-42 was to develop a guide, for DOTs and others, for managing bridge runoff to protect environmental quality and meet regulatory require- ments. The guide is intended to address such critical issues as characterization of bridge runoff and its effects on quality of receiving waters; current and emerging runoff manage- ment strategies that may be beneficial and cost-effective for application to bridges; criteria for identifying appropriate runoff management strategies for particular bridges; how bridge owners may establish appropriate levels of effort to address bridge runoff issues at a par- ticular location; and how bridge owners may identify BMPs for bridge runoff and select or develop BMPs for a particular location. A research team led by RBF Consulting, Carlsbad, CA, reviewed available literature and recent research, then systematically identified available bridge runoff management strate- gies and their likely benefits, lifecycle costs, and effectiveness in various settings. Using the information gathered, the team described a process and criteria DOTs can use to select BMPs for specific conditions where bridge runoff management is called for. The guide presents the process and runoff treatment practices in a way designed to facili- tate use by practitioners. It will assist agency staff and their advisors responsible for identify- ing and assessing the merits of options to manage stormwater runoff from specific highway bridges. This guide document is accompanied by computational spreadsheets that imple- ment the guideâs analysis process, available at the TRB web site at http://www.trb.org/Main/ Blurbs/170652.aspx. By Andrew C. Lemer Staff Officer Transportation Research Board
C O N T E N T S 1 Summary 4 Chapter 1 Overview 4 1.1 Purpose 4 1.2 Pollution Removal Benefit of the Treatment of Bridge Deck Runoff 5 1.3 Runoff Treatment Evaluation Strategy 7 1.4 BMP Selection and Evaluation 8 1.5 Organization of the Guide 9 Chapter 2 State of the Practice 9 2.1 State of the Practice for Bridge Stormwater Management 9 2.1.1 Systems for Bridge Deck Runoff Capture 10 2.1.2 DOT Runoff Management Strategies for Bridges: Highlights from Interviews 11 2.1.3 Considerations and Limitations of Conveyance and Treatment as Identified by DOTs 11 2.1.4 Source Control Approaches 13 2.1.5 Other Strategies 13 2.2 Overview of Regulatory Requirements 13 2.2.1 NPDES Permits 14 2.2.2 Wetland Permitting 15 2.2.3 CWA Section 401 Water Quality Certification 15 2.3 Evaluation of Receiving Water Impacts 15 2.3.1 Bridge Deck Runoff Quality 16 2.3.2 Receiving Water Studies 18 2.3.3 Stormwater Quantity Impacts 18 2.3.4 Summary 19 Chapter 3 Assessment Procedure 19 3.1 Overview of Assessment Approach 19 3.1.1 Rural Areas 19 3.1.2 Urban Areas 20 3.1.3 Special Situations 20 3.1.4 Summary 20 3.2 Simple Assessment Procedure 21 3.3 Complex Assessment Procedure 21 3.3.1 Stream Environment 22 3.3.2 Lake Environment 22 3.3.3 Coastal Inlet Environment
24 Chapter 4 Stormwater and Other Source Control Practices to Consider for All Bridges 24 4.1 Collection and Conveyance of Deck Runoff 24 4.1.1 Scour Protection at Collection System Discharge Points 25 4.2 Bird Roosting 25 4.2.1 Background 26 4.2.2 BMPs to Discourage Roosting under Bridges 27 4.3 Bridge Construction Materials 28 4.4 Bridge Maintenance 28 4.4.1 Painting Materials and Methods 29 4.4.2 Bridge Washing 29 4.4.3 Winter Maintenance 31 4.4.4 Sweeping 33 4.4.5 Scupper Plugs 34 4.4.6 Summary 34 4.5 Bridge Inspection 36 Chapter 5 Stormwater Treatment Controls for Bridges 36 5.1 Tool Overview 37 5.2 Bridge Deck Conveyance Systems 38 5.2.1 Offset Deck Drain and Raised Scuppers 39 5.3 Treatment Controls 39 5.3.1 Treatment at the Abutment 43 5.3.2 Bridge Scupper Treatment Concept 44 5.3.3 PFC 45 5.3.4 Floating Pile Wetland 46 5.3.5 Offsite Mitigation 47 5.4 Spill Controls 47 5.4.1 Bridge Spill Frequency 47 5.4.2 Bridge Spill Costs 47 5.4.3 Bridge Spill Characteristics 48 5.4.4 Recommended Spill Control Criteria 48 5.4.5 Recommended Structural Spill Control BMPs 48 5.4.6 Spill Control Case Studies 50 Chapter 6 BMP Evaluation Tool 50 6.1 BMP Evaluation Tool Overview 50 6.1.1 Tool Assessment Functions 50 6.1.2 Tool Calculation Methodology 51 6.1.3 Pollutant Loading 52 6.1.4 Tool Inputs 52 6.1.5 Tool Results and Interpretations 54 6.1.6 Tool Supporting Data 54 6.2 Worked Example of Tool 54 6.2.1 Project Locations and Climate Selection 54 6.2.2 Project Options 54 6.2.3 Project Design 56 6.2.4 Results 58 6.3 Tool Customization 58 6.4 Tool Intended Uses
58 6.4.1 Direct Tool Uses 59 6.4.2 Indirect Tool Uses 60 References A-1 Appendix A Literature Review B-1 Appendix B Simple and Complex Assessment Methods and Worked Example C-1 Appendix C Quick Start Guide D-1 Appendix D Userâs Guide for the BMP Evaluation Tool E-1 Appendix E BMP Evaluation Tool Modeling Methodology Note: Many of the photographs, figures, and tables in this report have been converted from color to grayscale for printing. The electronic version of the report (posted on the Web at www.trb.org) retains the color versions.
