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South Dakota Department of Transportation
Project Synopsis
SD1996-12


Title: Guidelines for Straight Salt and Salt/Sand Mixture
Project Researcher: Dan Johnston, SDDOT
Project Manager: Dave Huft
Research Period: -
Status: Approved
Cost: $25,000.00

Problem Statement:Certain winter road conditions can be difficult to treat using standard sand/salt mixtures. If temperatures are fairly cold and snow or ice pack is thick, sand/salt mixtures may not penetrate effectively or initiate melting. In spite of repeated applications, the snow pack can harden and become resistant to plowing. In such conditions, it may be more effective to apply straight salt instead of sand/salt.

Applied straight, salt can initiate melting, enable the snow or ice to be removed by plowing, and allow the road to dry. Because fewer applications are necessary, considerable savings in equipment and manpower may be possible. Because truckloads of straight salt extend ten to twenty times farther than loads of salt/sand mixture, response time and efficiency could improve. Highway safety should generally benefit. Ironically, less salt might be applied to the highway in a single straight application than in repeated but ineffective applications of sand/salt mixture.

Closely related to the issue of salt use is the question of whether ground-speed controlled, zero-velocity spreaders can reduce chemical waste. By dropping (rather than throwing) consistent amounts of chemical regardless of truck speed, the spreaders can improve salt retention, allowing gross application rates to be lowered.

Research is needed to determine whether straight salt can be used effectively and, if so, to establish criteria and guidelines for its proper use. The research should compare the total amounts of chloride applied on the road and into the environment when use of straight salt is and is not allowed. Finally, the research should assess the costs and benefits associated with use of ground-speed controlled zero-velocity spreaders.

Findings:
Title: Guidelines for Straight Salt and Salt/Sand Mixture
Project Researcher: Dan Johnston, DOT
Project Manager: Dave Huft
Research Period: -
Status: Approved
Cost: $25,000.00

Problem Statement:Certain winter road conditions can be difficult to treat using standard sand/salt mixtures. If temperatures are fairly cold and snow or ice pack is thick, sand/salt mixtures may not penetrate effectively or initiate melting. In spite of repeated applications, the snow pack can harden and become resistant to plowing. In such conditions, it may be more effective to apply straight salt instead of sand/salt.

Applied straight, salt can initiate melting, enable the snow or ice to be removed by plowing, and allow the road to dry. Because fewer applications are necessary, considerable savings in equipment and manpower may be possible. Because truckloads of straight salt extend ten to twenty times farther than loads of salt/sand mixture, response time and efficiency could improve. Highway safety should generally benefit. Ironically, less salt might be applied to the highway in a single straight application than in repeated but ineffective applications of sand/salt mixture.

Closely related to the issue of salt use is the question of whether ground-speed controlled, zero-velocity spreaders can reduce chemical waste. By dropping (rather than throwing) consistent amounts of chemical regardless of truck speed, the spreaders can improve salt retention, allowing gross application rates to be lowered.

Research is needed to determine whether straight salt can be used effectively and, if so, to establish criteria and guidelines for its proper use. The research should compare the total amounts of chloride applied on the road and into the environment when use of straight salt is and is not allowed. Finally, the research should assess the costs and benefits associated with use of ground-speed controlled zero-velocity spreaders.

Findings:

Research Objectives:
1  To develop guidelines for proper use of straight salt and salt/sand mixture in deicing and anti-icing applications.
2  To assess the field performance, cost-effectiveness, equipment and manpower requirements, and chloride exposure associated with use of straight salt and salt/sand mixture.
3  To evaluate ground-speed controlled zero-velocity spreaders for application of straight salt chemicals.

Research Tasks:
1  Meet with the project's technical panel to review project scope and work plan.
2  Propose material application guidelines for dry and pre-wetted salt and salt/sand mixture, and protocols to be used in their evaluation, for review and approval by the project's technical panel.
3  Organize field staff to conduct and evaluate tests at two geographically separated test locations and establish procedures for tracking material use and application costs.
4  Test sand/salt mixture stockpiles for chloride content.
5  Collect information on storm events, material use, application time and cost, and material effectiveness for salt and salt/sand mixture at both test locations.
6  Analyze data to assess both material's field performance, cost and cost-effectiveness and to refine application rates and conditions appropriate to each material.
7  Describe the field performance, cost and cost-effectiveness of ground-speed controlled zero-velocity spreaders and assess their impact on the use of straight salt deicer.
8  Prepare a final report and executive summary of the literature review, research methodology, findings, conclusions, and recommendations.
9  Make an executive presentation to the SDDOT Research Review Board at conclusion of the project.

Documents Available:

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