1. Recent Findings on Road Salt in Maine’s Impaired Streams By Mark Whiting Maine DEP

2. Discussion Topics Review of Penjajawoc Stream, Bangor ME Review of Penjajawoc Stream, Bangor ME Review of MDOT study from 30 years ago Review of MDOT study from 30 years ago Why do we use road salt? Why do we use road salt? What can be done? What can be done?

5. Chloride Medians for Penjajawoc Stream

10. Stormwater BMPs Erosion Control Erosion Control Detention Detention Infiltration Infiltration Filtration Filtration CSOs CSOs Housecleaning Housecleaning There is no BMP treatment for salt! There is no BMP treatment for salt!

11. Why use road salt? Salts are cheap and effective de-icers. Salts are cheap and effective de-icers. Maine has more people on the road, driving more hours, and yet road winter road fatalities are way down. Maine has more people on the road, driving more hours, and yet road winter road fatalities are way down. Pre-treatment of roads with brine, esp. calcium or magnesium salts prevent ice from binding with the road surface. Pre-treatment of roads with brine, esp. calcium or magnesium salts prevent ice from binding with the road surface. Ca and Mg salts are effective below 15º F Ca and Mg salts are effective below 15º F Airports cannot use sand Airports cannot use sand

12. Why use road salt (continued)? Current winter road maintenance favors a “bare road” plan for all primary roads that allows people to travel faster. This has been successful while also reducing the number of accidents and fatalities. A bare road plan requires the use of salt. The amount of salt used for a given mile of road has been increasing nationwide. Current winter road maintenance favors a “bare road” plan for all primary roads that allows people to travel faster. This has been successful while also reducing the number of accidents and fatalities. A bare road plan requires the use of salt. The amount of salt used for a given mile of road has been increasing nationwide.

14. From Margaret Chase Smith Policy Center Report

15. Sources of Salt in Surface and Groundwater Natural sources, atmospheric deposition of ocean aerosols, decomposition of organic matter Natural sources, atmospheric deposition of ocean aerosols, decomposition of organic matter Road salt, in Maine there was about 490,000 tons/yr for 2008-2009, 21 tons/mile of road Road salt, in Maine there was about 490,000 tons/yr for 2008-2009, 21 tons/mile of road Landfills and organic debris Landfills and organic debris Water softeners Water softeners

16. From NH DES TMDL Study

17. From NH TMDL Study

18. From Margaret Chase Smith Policy Center Report

19. Problems from Salt Sodium is a nutrient, but too much is bad. Drinking water standard is 250 mg/L, but 20 mg/L is the limit for people with salt restricted diets. Sodium is a nutrient, but too much is bad. Drinking water standard is 250 mg/L, but 20 mg/L is the limit for people with salt restricted diets. Chloride is not a nutrient, but it is abundant in body fluids. The Maine Aquatic Life standard is 230 mg/L for chronic exposures (≥ 4 days). Chloride is not a nutrient, but it is abundant in body fluids. The Maine Aquatic Life standard is 230 mg/L for chronic exposures (≥ 4 days). Salts acidify soils and leach nutrients from soils and from plant tissues, & decrease surface water alkalinity by leaching away cations (esp. Ca & Mg) Salts acidify soils and leach nutrients from soils and from plant tissues, & decrease surface water alkalinity by leaching away cations (esp. Ca & Mg) Lakes can develop haloclines that trap nutrients Lakes can develop haloclines that trap nutrients Corrosion of metals (esp. cars and bridges) and damage to road surfaces (esp. concrete) Corrosion of metals (esp. cars and bridges) and damage to road surfaces (esp. concrete)

20. Season is important Most groundwater recharge occurs in the late winter and early spring associated with spring melts. These conditions also mobilize salts. Most groundwater recharge occurs in the late winter and early spring associated with spring melts. These conditions also mobilize salts. Spring melts strongly affect surface runoff too. Peak conductivity generally occurs from Feb to April during these thaws. Spring melts strongly affect surface runoff too. Peak conductivity generally occurs from Feb to April during these thaws.

21. Summary of Peak Observed Chloride Concentrations (from Environment Canada)

22. Long-term trends Background Cl concentrations are probably about 20-30 mg/L for Atlantic states, the Canadian shield provinces have some of the lowest 1-5 mg/L Background Cl concentrations are probably about 20-30 mg/L for Atlantic states, the Canadian shield provinces have some of the lowest 1-5 mg/L Salt concentrations are increasing in groundwater, soils, and surface water in all northern states and Canada. Salt concentrations are increasing in groundwater, soils, and surface water in all northern states and Canada.

23. BMPs for better water quality Don’t use more salt than you need, and use modern mixes. Don’t use more salt than you need, and use modern mixes. Application strategies, salt mixes, pre-wetting, pre-application of brine using Ca or Mg salts, weather sensors, bridges my have built in applicators (MN, ON). Application strategies, salt mixes, pre-wetting, pre-application of brine using Ca or Mg salts, weather sensors, bridges my have built in applicators (MN, ON). Better road designs, better tires. Better road designs, better tires. Sand only applications (parking lots?) Sand only applications (parking lots?) Stay home in bad weather. Stay home in bad weather.

24. BMP’s for Better Water Quality Apply at the right place (i.e., hills, curves, bridges and shaded patches of road need special attention) Apply at the right place (i.e., hills, curves, bridges and shaded patches of road need special attention) Apply at the right time (i.e., as early as possible, prevention works better than reaction, anti-icers applications can work for days and prevent ice from bonding with the road) Apply at the right time (i.e., as early as possible, prevention works better than reaction, anti-icers applications can work for days and prevent ice from bonding with the road) Factor in expected traffic volume, day/night temperature changes, etc. Factor in expected traffic volume, day/night temperature changes, etc.

25. More BMP’s Salt storage areas need to be covered Salt storage areas need to be covered Snow dumps must be remote from sensitive locations Snow dumps must be remote from sensitive locations Use green deicers such as organic salts, i.e., calcium magnesium acetate, potassium acetate, sodium acetate Use green deicers such as organic salts, i.e., calcium magnesium acetate, potassium acetate, sodium acetate Low salt techniques can save money and improve public safety Low salt techniques can save money and improve public safety