Stormwater treatment of bridge deck runoff continues to be a design challenge. Traditional methods of treating this runoff suggest treating an equivalent area of roadway offsite that discharges to the same receiving water body or piping the bridge deck stormwater to an offsite treatment location. NCHRP_Report_778: Bridge Stormwater Runoff Analysis and Treatment Options concludes that treatment of runoff from a comparable section of highway on land is preferable to treatment of runoff from the bridge deck. Where offsite mitigation is unacceptable due to (1) water quality restrictions placed on the receiving water body or (2) site-specific conditions making the piping of bridge runoff to bridge ends for offsite treatment infeasible or undesirable, stormwater designers have few options for effective on-bridge treatment of stormwater.
There is a growing need to develop more options for on-bridge treatment of stormwater. In addition to NCHRP_Report_778, the following reports provide relevant background on this topic and support the need for further research thereon:
- NCHRP_Report_767: Measuring and Removing Dissolved Metals from Stormwater in Highly Urbanized Areas
- NCHRP Web-Only Document 265: Field Testing of BMPs Using Granulated Ferric Oxide Media to Remove Dissolved Metals in Roadway Stormwater Runoff (pending)
Research is needed to address on-bridge stormwater treatment challenges, including, but not limited to level of service; structural integrity; hydraulic function (including spread width); litter and sediment loads; freeze-thaw cycles; maintenance operations; and work zone safety.
The objectives of this research are to develop the following:
(1) On-bridge stormwater treatment applications with a focus on retrofitting existing bridges utilizing proven stormwater treatment practices; and
(2) Guidelines for selection (e.g., by media and materials), design, placement, and maintenance of the developed on-bridge stormwater treatment applications. The primary users of these guidelines will be bridge and hydraulic designers.
Accomplishment of the project objective(s) will require at least the following tasks.
Task descriptions are intended to provide a framework for conducting the research. The NCHRP is seeking the insights of proposers on how best to achieve the research objectives. Proposers are expected to describe research plans that can realistically be accomplished within the constraints of available funds and contract time. Proposals must present the proposers’ current thinking in sufficient detail to demonstrate their understanding of the issues and the soundness of their approach to meeting the research objectives.
Task 1. Literature review and proposal of on-bridge stormwater treatment practices for development. Work under this task should be divided into two concurrent subtasks:
Task 1a. Conduct literature review of relevant stormwater treatment practices. Identify treatment mechanisms, including filter media, filter media mixes, and other materials that have demonstrated effective removal of the major classes of highway runoff pollutants from stormwater, with focus on dissolved pollutants. Provide a comparison of long-term pollutant removal efficiency of materials or mixes to hydraulic capacity and cost.
Task 1b: Propose on-bridge stormwater treatment practices for development. With consideration of current treatment practices identified in Task 1a, propose at least three practical on-bridge stormwater treatment practices for development in this project, with at least one involving media filtration. The configurations should (a) be suitable for bridge retrofit scenarios without impacting the structural integrity and serviceability of the bridge; (b) have appropriate hydraulic characteristics for efficient drainage under all climatic conditions; (c) allow for easy access and typical (e.g., annual) maintenance; (d) continue to meet AASHTO spread width criteria if the practice should fail; and (e) use readily available materials approved under state or municipal agency specifications, unless justification for alternative materials can be provided.
Task 2. Submit Interim Report 1. This report shall summarize findings from Task 1, provide hydraulic and structural design assumptions, and provide recommendations on two or more bridge treatment applications for further development. Interim Report 1 shall propose strategies for laboratory testing of water quality and field demonstration of installation and removal. Following NCHRP review of the report, the applications to be developed will be discussed at an interim meeting. NCHRP approval of Interim Report 1 is required before proceeding with Task 3. The interim meeting will be held at TRB offices in Washington, D.C.
Task 3. Develop and test stormwater treatment practices. As a first step, develop a quality assurance project plan (QAPP) for the selected testing strategies from Task 2. The QAPP should include:
- Use of state-certified water quality laboratories
- Description and schematic(s) of site or experiment design
- Methods for litter and traction sand loading to simulate clogging of media filtration
Task 4. Submit Interim Report 2. This report shall summarize findings from Task 3, including discussion of variables affecting performance that could not be addressed by this project. Following NCHRP review of the report, Interim Report 2 will be discussed at an interim meeting, along with an outline for draft guidelines to be developed in Task 5. NCHRP approval of Interim Report 2 is required before proceeding with Task 5.
Task 5. Develop guidelines for the chosen practices. The guidelines shall include recommendations and constraints for each of the following: appropriate bridge site selection, design specifications, constructability, and maintenance. These guidelines should be consistent with the findings of both Interim Reports and provide presentation materials that summarize the results of the research and could be used for multiple purposes and audiences.
Note: Following receipt of the draft final deliverables, the remaining 3 months shall be for NCHRP review and comment and for research agency preparation of the final deliverables.
A. Proposals should include a task-by-task breakdown of labor hours for each staff member as shown in Figure 4 in the brochure, "Information and Instructions for Preparing Proposals" (http://onlinepubs.trb.org/onlinepubs/crp/docs/ProposalPrep.pdf). Proposals also should include a breakdown of all costs (e.g., wages, indirect costs, travel, materials, and total) for each task using Figures 5 and 6 in the brochure. Please note that TRB Cooperative Research Program subawards (selected proposers are considered subawards to the National Academy of Sciences, the parent organization of TRB) must comply with 2 CFR 200 – Uniform Administrative Requirements, Cost Principles, and Audit Requirements for Federal Awards. These requirements include a provision that proposers without a "federally" Negotiated Indirect Costs Rate Agreement (NICRA) shall be subject to a maximum allowable indirect rate of 10% of Modified Total Direct Costs. Modified Total Direct Costs include all salaries and wages, applicable fringe benefits, materials and supplies, services, travel, and up to the first $25,000 of each lower-tier subaward and subcontract. Modified Total Direct Costs exclude equipment, capital expenditures, charges for patient care, rental costs, tuition remission, scholarships and fellowships, participant support costs and the portion of each lower-tier subaward and subcontract in excess of $25,000.
B. NCHRP is a practical, applied research program that produces implementable products addressing problems faced by transportation practitioners and managers. The benefits of NCHRP research are realized only when the results are implemented in state DOTs and other agencies. Implementation of the research product must be considered throughout the process, from problem statement development to research contract and beyond completion of the research. Item 4(c), "Anticipated Research Results," must include the following: (a) the "product" expected from the research, (b) the audience or "market" for this product, (c) a realistic assessment of impediments to successful implementation, and (d) the institutions and individuals who might take leadership in deploying the research product. The project panel will develop and maintain an implementation plan throughout the life of the project. The research team will be expected to provide input to an implementation team consisting of panel members, AASHTO committee members, the NCHRP Implementation Coordinator, and others in order to meet the goals of NCHRP Active Implementation: Moving Research into Practice, available at http://onlinepubs.trb.org/onlinepubs/nchrp/docs/NCHRP_ActiveImplementation.pdf.
C. Item 5 in the proposal, "Qualifications of the Research Team," must include a section labeled "Disclosure." Information relevant to the NCHRP's need to ensure objectivity and to be aware of possible sources of significant financial or organizational conflict of interest in conducting the research must be presented in this section of the proposal. For example, under certain conditions, ownership of the proposing agency, other organizational relationships, or proprietary rights and interests could be perceived as jeopardizing an objective approach to the research effort, and proposers are asked to disclose any such circumstances and to explain how they will be accounted for in this study. If there are no issues related to objectivity, this should be stated.
D. Proposals are evaluated by the NCHRP staff and project panels consisting of individuals collectively very knowledgeable in the problem area. Selection of an agency is made by the project panel considering the following factors: (1) the proposer's demonstrated understanding of the problem; (2) the merit of the proposed research approach and experiment design; (3) the experience, qualifications, and objectivity of the research team in the same or closely related problem area; (4) the plan for ensuring application of results; (5) how the proposer approaches inclusion and diversity in the composition of their team and research approach, including participation by certified Disadvantaged Business Enterprises; and, if relevant, (6) the adequacy of the facilities.
Note: The proposer's approach to inclusion and diversity as well as participation by Disadvantaged Business Enterprises should be incorporated in Item 12 of the proposal.
E. Copyrights - All data, written materials, computer software, graphic and photographic images, and other information prepared under the contract and the copyrights therein shall be owned by the National Academies of Sciences, Engineering, and Medicine. The contractor and subcontractors will be able to publish this material for non-commercial purposes, for internal use, or to further academic research or studies with permission from TRB Cooperative Research Programs. The contractor and subcontractors will not be allowed to sell the project material without prior approval by the National Academies of Sciences, Engineering, and Medicine. By signing a contract with the National Academy of Sciences, contractors accept legal responsibility for any copyright infringement that may exist in work done for TRB. Contractors are therefore responsible for obtaining all necessary permissions for use of copyrighted material in TRB's Cooperative Research Programs publications. For guidance on TRB's policies on using copyrighted material please consult Section 5.4, "Use of Copyrighted Material," in the Procedural Manual for Contractors.