Recent Findings on Road Recent Findings on Road Salt in Maine’s Impaired Salt in Maine’s Impaired

StreamsStreamsBy Mark WhitingBy Mark Whiting

Maine DEPMaine DEP

Discussion TopicsDiscussion Topics

Review of Penjajawoc Stream, Bangor MEReview of Penjajawoc Stream, Bangor ME Review of MDOT study from 30 years agoReview 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?

Cemetery Br

Meadow Br

EMCC

Penjajawoc and Meadow Brook, Conversion of Cond to Chloride

y = 0.2629x - 5.3839

R2 = 0.9837

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Chloride Medians for Penjajawoc Chloride Medians for Penjajawoc StreamStream

Sites Name Median Range

PJS-6 BLT 64 10-163 mg/L ClPJS-5 Marsh 24 17-32 mg/L ClPJS-4 Above Stillwater 35 17-65 mg/L ClPJS-4b Above Stillwater 42 17-129 mg/L ClPJS-3 Above I-95 100 33-205 mg/L ClPJS-2 Above Mt Hope 127 25-1113 mg/L ClPJS-1 Above Route 2 143 17-836 mg/L Cl

MB-1 Meadow 338 73-836 mg/L Cl

CB-1 Cemetery 76 17-95 mg/L Cl

Chloride

Penjajawoc Stream at Evergreen Woods 2008

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Meadow Brook, Sonde Record Feb-Mar 2008

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1982 MDOT Study of NaCl in the Penjajawoc

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Study Sites

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Penjajawoc Stream Median Chloride for 2008-2009

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AboveRoute 2

Meadow Cemetery

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Stormwater BMPsStormwater BMPs

Erosion ControlErosion Control DetentionDetention InfiltrationInfiltration FiltrationFiltration CSOsCSOs HousecleaningHousecleaning There is no BMP treatment for salt!There is no BMP treatment for salt!

Why use road salt?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 Maine has more people on the road, driving

more hours, and yet road winter road fatalities more hours, and yet road winter road fatalities are way down.are way down.

Pre-treatment of roads with brine, esp. calcium Pre-treatment of roads with brine, esp. calcium or magnesium salts prevent ice from binding or magnesium salts prevent ice from binding with the road surface.with the road surface.

Ca and Mg salts are effective below 15Ca and Mg salts are effective below 15º Fº F Airports cannot use sandAirports cannot use sand

Why use road salt (continued)?Why use road salt (continued)?

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

Summary of Road Salts Used by Ontario for 1997/1998 in Metric Tons

,Sodium chloride4,700,000

,Calcium chloride107,992

,Magnesium chloride25,000

,Potassium chloride2,000

Average Cost per Ton for Different Winter De-icers

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From Margaret Chase Smith Policy Center Report

Sources of Salt in Surface and Sources of Salt in Surface and GroundwaterGroundwater

Natural sources, atmospheric deposition of Natural sources, atmospheric deposition of ocean aerosols, decomposition of organic ocean aerosols, decomposition of organic mattermatter

Road salt, in Maine there was about 490,000 Road salt, in Maine there was about 490,000 tons/yr for 2008-2009, 21 tons/mile of roadtons/yr for 2008-2009, 21 tons/mile of road

Landfills and organic debrisLandfills and organic debris Water softenersWater softeners

Salt Sources in Porcupine Br. Watershed from New Hampshire TMDL Study

Salt Storage Piles7%

Parking Lots50%

Private Roads3%

Municipal Roads27%

State Roads9%

Atmospheric Deposition1% Food Waste

1% Water Softeners2%

From NH DES TMDL Study

Scources of Salts in the Dinsmore Brook watershed New Hampshire from TMDL Report

Parking Lots26%

Private Roads21%Municipal Roads

2%

State Roads50%

AtmosphericDeposition

1%

Food Waste0%

Water Softeners0%Salt Storage Piles

0%

From NH TMDL Study

Pattern of Statewide Salt Use, by End User

MDOT19%

Maine TurnpikeAuthority

3%

Municipal54%

Private15%

All Other9%

From Margaret Chase Smith Policy Center Report

Problems from SaltProblems from Salt Sodium is a nutrient, but too much is bad. Drinking Sodium is a nutrient, but too much is bad. Drinking

water standard is 250 mg/L, but 20 mg/L is the limit water standard is 250 mg/L, but 20 mg/L is the limit for people with salt restricted diets.for people with salt restricted diets.

Chloride is not a nutrient, but it is abundant in body Chloride is not a nutrient, but it is abundant in body fluids. The Maine Aquatic Life standard is 230 mg/L fluids. The Maine Aquatic Life standard is 230 mg/L for chronic exposures (for chronic exposures (≥ 4 days)≥ 4 days)..

Salts acidify soils and leach nutrients from soils and Salts acidify soils and leach nutrients from soils and from plant tissues, & decrease surface water from plant tissues, & decrease surface water alkalinity by leaching away cations (esp. Ca & Mg)alkalinity by leaching away cations (esp. Ca & Mg)

Lakes can develop haloclines that trap nutrientsLakes can develop haloclines that trap nutrients Corrosion of metals (esp. cars and bridges) and Corrosion of metals (esp. cars and bridges) and

damage to road surfaces (esp. concrete)damage to road surfaces (esp. concrete)

Season is importantSeason is important

Most groundwater recharge occurs in the late Most groundwater recharge occurs in the late winter and early spring associated with spring winter and early spring associated with spring melts. These conditions also mobilize salts.melts. These conditions also mobilize salts.

Spring melts strongly affect surface runoff too. Spring melts strongly affect surface runoff too. Peak conductivity generally occurs from Feb Peak conductivity generally occurs from Feb to April during these thaws.to April during these thaws.

Summary of Peak Observed Summary of Peak Observed Chloride Concentrations (from Chloride Concentrations (from

Environment Canada)Environment Canada)

Peak ChlorideNormal Freshwater 20-50 mg/LUrban Streams in Winter/Spring over 1000 mg/LGroundwater 2800 mg/LSnow Dump Runoff 3000-5000 mg/LHighway Runoff over 18,000 mg/LOcean Water 25,000-30,000 mg/LSalt Storage Runoff 82,000 mg/L

Long-term trendsLong-term trends

Background Cl concentrations are probably Background Cl concentrations are probably about 20-30 mg/L for Atlantic states, the about 20-30 mg/L for Atlantic states, the Canadian shield provinces have some of the Canadian shield provinces have some of the lowest 1-5 mg/Llowest 1-5 mg/L

Salt concentrations are increasing in Salt concentrations are increasing in groundwater, soils, and surface water in all groundwater, soils, and surface water in all northern states and Canada.northern states and Canada.

BMPs for better water qualityBMPs for better water quality

Don’t use more salt than you need, and use Don’t use more salt than you need, and use modern mixes.modern mixes.

Application strategies, salt mixes, pre-wetting, Application strategies, salt mixes, pre-wetting, pre-application of brine using Ca or Mg salts, pre-application of brine using Ca or Mg salts, weather sensors, bridges my have built in weather sensors, bridges my have built in applicators (MN, ON).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.

BMP’s for Better Water QualityBMP’s for Better Water Quality

Apply at the right place (i.e., hills, curves, Apply at the right place (i.e., hills, curves, bridges and shaded patches of road need bridges and shaded patches of road need special attention)special attention)

Apply at the right time (i.e., as early as Apply at the right time (i.e., as early as possible, prevention works better than possible, prevention works better than reaction, anti-icers applications can work for reaction, anti-icers applications can work for days and prevent ice from bonding with the days and prevent ice from bonding with the road)road)

Factor in expected traffic volume, day/night Factor in expected traffic volume, day/night temperature changes, etc.temperature changes, etc.

More BMP’sMore BMP’s

Salt storage areas need to be coveredSalt storage areas need to be covered Snow dumps must be remote from sensitive Snow dumps must be remote from sensitive

locationslocations Use green deicers such as organic salts, i.e., Use green deicers such as organic salts, i.e.,

calcium magnesium acetate, potassium acetate, calcium magnesium acetate, potassium acetate, sodium acetatesodium acetate

Low salt techniques can save money and Low salt techniques can save money and improve public safetyimprove public safety