There are still many areas related to chloride where additional research and information may help to inform management decisions. There are 12 main areas that would benefit from additional information.
- Chloride reductions when implementing the BMPs. The WMAt is the first ever, exhaustive resource of all known salt saving BMPs. The reduction potential for each BMP is largely unknown. The WMAt is limited by available research, in how much of a reduction that can be attained by improving each individual practice. More research is needed on many BMPs to understand how much salt can be saved when the BMP is implemented. The tool contains a list of over 200 BMPs, most of which would benefit from reduction potential research.
- For example, an estimated 17% of salt is lost by storing salt/sand pile uncovered over the winter. By implementing the recommended BMP of storing salt/sand pile indoor, there is an estimated 17% reduction potential for that pile
- For example, no information is available on the percent salt savings attained from increasing liquid to granular ratio from 8 gallons per ton to 50 gallons per ton. This information may help decision makers select those BMPs that achieve the greatest chloride reduction.
- Water softening options. More information is needed on the effectiveness of various water softening systems at reducing chloride and the relative cost for each. The current available options for possibly reducing chloride from this source includes: converting old home water softening to on-demand softeners; eliminating home softeners with a centralized lime softening; and converting to non-chloride water conditioning in home systems. Developing a better understanding of the cost associated with such conversions would also aid in proper decision-making. Information on potential chloride reductions resulting from a more informed public would be beneficial. This would include a public that knows untreated hardness level, understands reasonably acceptable hardness levels for home use, and sets the water softeners appropriately.
- Environmental impacts of non-chloride deicers. There are many alternative deicers that do not contain chloride; however, all have negative environmental impacts. A thorough review of all practical alternatives that exist with detailed information on the short-term and long-term environmental impacts and how it compares to chloride containing deicers in effectiveness and environmental impacts would allow more informed. Currently research about short term environmental impacts has been done on a variety of chloride and non-chloride deicers by the Clear Roads research consortium.
- Citizen attitudes and practices around the use of chloride. Demonstration projects can be used to test the organizing approaches for building partnerships between citizens and government or property owners to work together to solve the challenge of chloride use and water resource impairments. The demonstrations will likely be most successful where community capacity around environmental issues exists. Local leaders should be supported to experiment with building partnerships across sectors to co-develop strategies for chloride reductions by municipalities, businesses, and households. The demonstrations can employ pre- and post-evaluation to determine whether the approach achieves meaningful outcomes over time. The outcomes will determine whether the efforts should expand past the pilot stage. If defined outcomes are significant, the plan should be developed to scale to metro-wide and beyond application.
- Effectively educate the public about environmental impacts of salt use and how they can help reduce it. Research is needed for the most effective way to educate the public to make changes. A multi-agency approach is needed to reach the greatest public audience.
- Will the traditional salt savings steps recommended in this plan be enough? If all the TCMA maintenance organization use the WMAt and show their practices are dominated by excellent practices, the information will show if these traditional BMPs will reduce salt enough to make the practices sustainable. It is difficult to project when, or if, this will occur. It is important to monitor the progress of the industry and compare to the water monitoring results. If there is a high compliance with traditional BMPs it will illustrate the effectiveness and demonstrate whether there can be a sustainable ecosystem and the use of salt for winter maintenance. This answer would be of high importance for all dealing with the same situation.
- Pavement alternatives. Additional research should be done to understand pavement types and emerging pavement technologies that could reduce chloride usage while providing an adequate level of service.
- Water experts. Research is needed to better understand how to capture chloride before it enters the water and how to remove it once it enters our surface water or ground water. Special attention should be directed toward preserving the food chain living in surface water systems when considering filtration methods for removing chloride from lakes, rivers, and wetlands.
- Reuse. An evaluation of the feasibility of re-using wastewater with chloride for winter maintenance should be conducted, including brine from RO processes. As part of this evaluation, an understanding of the other chemicals present in the wastewater will be important in determining the feasibility of re-using wastewater.
- Non-chloride and reduced chloride. The MnDOT has evaluated many different options for deicing, but some may need additional research into the effectiveness. Information can be found at “Chloride Free Snow and Ice Control Material.”
- Septic Systems. More research into septic systems and the amount of chloride loading to the groundwater needs to be better understood as well as other contributors of chloride to groundwater.
- Climate Change. Additional research is needed to understand how climate change will affect precipitation patterns and temperatures and their effects on chloride. Precipitation and temperature could cause increases or decreases in chloride application. However, increased or decreased precipitation could also affect the amount of runoff available for dilution and flushing of chloride.