NCHRP 06-16 [Completed]
Guidelines for the Selection of Snow and Ice Control Materials To Mitigate Environmental Impacts
| Project Data
||Levelton Consultants, Ltd.|
||Brent T. Mussato|
Every year, considerable quantities of snow and ice control products are applied to highways, and environmental and regulatory agencies have questioned the environmental impact of these products. Transportation agencies are asked to use "environmentally friendly" or less toxic alternatives wherever possible, but there is no commonly accepted guidance for determining which products meet these criteria. The traditional use of road salt has been prohibited in some locations, leaving highway agencies uncertain about how traffic safety can be maintained in bad weather. For example, Environment Canada has concluded that inorganic chloride road salts are harmful to the environment under the Canadian Environmental Protection Act, thus requiring development and implementation of improved management practices.
Studies of the most common chemical alternatives--sodium chloride (salt), magnesium chloride, calcium chloride, calcium magnesium acetate, potassium acetate, and urea--have focused on performance and cost under various weather conditions without evaluating their relative impacts on the environment. Several new chemical preparations, including some that are trademarked, have entered the market as snow and ice control chemicals for use by transportation agencies, but there is limited information about their environmental impacts.
There is a need for rational decision-making guidelines to assist DOT maintenance managers in selecting the most appropriate snow and ice control materials for the conditions that exist in their jurisdictions.
The objective of this project was to develop guidelines for selection of snow and ice control chemicals and abrasives, based on their constituents, performance, environmental impacts, cost, and site-specific conditions.
For the purpose of this study, environmental impacts include effects on human health; aquatic life; flora and fauna; surface-water and groundwater quality; air quality; vehicles; and physical infrastructure including bridges, pavements, railway electronic signaling systems, and power distribution lines.
Accomplishment of the project objective required the following tasks.
TASKS (1.) Compile, analyze, critique, and document relevant domestic and international information, on the basis of applicability and usefulness to achieving the project objective. The review should include published information, current practices, and research in progress, and cover the following topic areas:
- Range of materials available for snow and ice control;
- Typical costs of materials;
- Ease of use and any health concerns associated with handling, storage, and application;
- Environmental impacts, primarily those related to common usage and application, but with consideration of impacts related to storage and disposal;
- Site-specific conditions that impact choice of material/locations where specific materials are prohibited or inadvisable;
- Current and proposed specifications used for acceptance and how they vary by jurisdiction (state and provincial agencies) or region; and
- The full range of parameters and test methods used to evaluate the performance and environmental impacts of the materials.
(2.) Summarize, categorize, and quantify the most significant factors that should be considered in the selection of materials. Identify trends that will affect the selection of snow and ice control materials in the near- to mid-term future.
(3.) Develop a draft framework for the proposed material selection guidelines. The draft framework should be presented in sufficient detail so as to illustrate the initial thinking of the contractors on how DOT maintenance managers will select snow and ice control materials, taking into account factors such as material properties and constituents, site-specific conditions (e.g., climate and proximity to wetlands or other sensitive areas), the regulatory environment, and storage and application procedures. The framework should specify the intended format for the guidelines, (e.g. decision tree or flowchart, spreadsheet application, or computer model). (4.) Identify and justify which test methods are most effective for measuring the properties and constituents that determine the environmental impacts of the current range of snow and ice control materials. These should include, but not be limited to, properties such as BOD, COD, pH level, toxicity, and corrosivity, and constituents such as heavy metals, nutrients, and additives. (5.) Identify gaps and needs from Tasks 1 through 4. Recommend areas where additional laboratory testing is required in this project to determine or verify the constituents and environmental impacts of current materials using the methods identified in Task 4 above. The contractor should ensure that the proposed tests are designed to produce statistically valid results. (6.) Submit an Interim Report that documents the results of Tasks 1 through 5 and includes a revised work plan for accomplishing the remaining tasks. The contractor will be expected to meet with the NCHRP approximately 1 month later. The research agency shall not begin work on the remaining tasks without NCHRP approval. (7.) Upon approval of the Interim Report by the NCHRP, conduct the laboratory testing identified in Task 5 and approved by the project panel. (8.) Produce a matrix describing currently available materials and their significant properties identified in Task 4 above. (9.) Develop a purchase specification and quality assurance test protocol for the evaluation of existing and future materials. (10.) Following the plan approved during review of the Interim Report, develop guidelines that incorporate (1) a decision-making process for the selection of snow and ice control chemicals and abrasives, based on their composition, performance, environmental impacts, cost and site-specific conditions; (2) the matrix of currently available products and their properties; (3) the purchase specification, and (4) the quality assurance test protocol. (11.) Submit the draft Task 10 guidelines to the NCHRP and to a sample of winter maintenance professionals for review. The reviewers should include a selection of DOT maintenance managers from U.S. states and Canadian provinces. The reviewers selected should include members of the Pacific Northwest Snowfighters Association and of AASHTO's Winter Maintenance Policy Coordinating Committee. (12.) Compile and submit the comments received from the reviewers, and submit a technical memorandum to the NCHRP indicating how the review comments will be addressed. (13.) Submit a final report that documents the entire research effort and includes the revised Task 10 guidelines as a stand-alone product. In addition, provide a companion executive summary that outlines the research results. Provide recommendations for research needed to further develop, refine, or implement the decision-making guidelines.
Status: The project has been completed. Additional funding has been provided to monitor the results of concrete corrosion testing, which were not complete at the end of the contract date.
Product availability: The final report has been published as NCHRP Report 577.
The Material Selection Decision Tool can be downloaded here (4,878 kB ZIP file). Once you download the ZIP file, double click to see the contents, and click on setup.exe to install the program.