Sunday, November 9, 2014

Kick the salt habit--for the sake our lakes

by Jim Baumann and David Thompson

Madison’s waterways are clearly impacted by winter salt use. Steadily increasing levels of chlorides from deicers have been found in all of Madison's Lakes, and in our wells.
Vultures feast on carp at Odana Pond-->

Odana Pond, at the western end of the Lake Wingra watershed, is listed as an impaired water due to very high chloride levels.  Most of the salt is from highways, streets and parking lots, but home use also contributes.

All deicers are bad for the environment

We checked the formulas for most deicer salts now available in Madison.  All are harmful to the lakes, your garden, and concrete; Most contain chloride. Some, like Pet Safe or Ace Ice Melter, even contain urea, a fertilizer.  Urea causes growth of toxic algae in the lakes.

The claims on the labels, like "safe for the environment" or "safe for concrete," are false.  So if you have ice on a slope, we recommend spreading sand.

If you must use deicer, consider these ways to reduce the quantity...

  • Limit use to no more than one pound of salt (NaCl) per 200 square feet of ice.
  • A heaping 12 ounce cup should be enough for a 60 foot icy sidewalk
  • A hand-held spreader helps you spread the salt evenly.
  • More salt does not mean more melting.
  • Salt will not work when the temperature is 15° F or lower.
  • If salt is visible on dry pavement, sweep up the extra salt for future use.
  • After March 1, most snow will melt within a few hours of falling.
  • Let the sun do your work.

Consider using the sun to remove ice on your sidewalk.  Few people realize that ice evaporates directly to water vapor, even when temperatures are well below zero.  It’s called “sublimation.“

You can speed sublimation by keeping your sidewalk shoveled.  Even if there is a thin layer of snow or ice remaining on the pavement, the sun will penetrate, heat the pavement underneath, and cause the overlying ice to sublimate.  If you sweep away a fresh dusting of snow, or chop some of the ice, the sun heats the spot of bare pavement, causing the surrounding ice to evaporate even faster.  Sublimation works even when it’s cloudy or really cold.

If you read the labels on deicer sacks, they instruct you to shovel snow first, and to remove any slush that forms.  The same method applies if you are using the sun to do your work.  So why not just forget the salt?

So touch up your sidewalk before you go to work, and let the sun do the rest of the work.

Dealing with thick ice

Ice forms when you don't remove all the snow--as happens with some snow blowers.  Another cause is when people walk on the snow, before you remove it.  The best defense against ice is to remove all the snow before people walk on it

It usually takes a few days for the remaining snow to turn to ice.  During that time, you can easily chip off the packed snow with an ice scraper.  Once the pavement is mostly bare, the sun will do the rest.

If you have a patch of very slick ice, it may be a sign that runoff is pooling on your sidewalk--trapped by the higher turf on either side.  The best remedy is to build a small rain garden next to the problem area.

Note: the sand that the City provides in barrels around town is 15% salt.

Salt--not worth the harm

Salt does work faster than relying on the sun.  But salt is useless when temperatures are low.  And when you consider the harm, it simply isn't worth the faster melting.

  • Bad for the lakes.
  • Bad for our drinking water.
  • Some salt mixes contain toxic additives
  • Salt tracks into your house.
  • Kills grass and gardens nearby, causing erosion.
  • Causes concrete and masonry to decay (below).

Thursday, April 26, 2012

Five Myths about Salt on our Roads


The city has been fighting a losing battle to reduce rock salt use since 1977, when they set a target of no more than 2,846 tons each winter. Since then, average annual use has increased by 265%. Missing the goal by so much means we have a complex problem--poorly understood by the public. The myths below persist because the effects of salt are largely invisible.

Friday, January 27, 2012

Unsustainable at CUNA

Salt storage area at CUNA headquarters in Madison, WI
Runoff is flowing through the spilled salt and into a storm sewer.

Tuesday, January 17, 2012

Volunteers monitoring road salt impacts on waterways across Wisconsin

By: Kris Stepenuck, DNR Bureau of Watershed Management
Reprinted from "MyDNR Digest" edited by Diane Brinson

The goal: collect high quality data on the impact of road salt on water quality conditions for aquatic organisms, while on a limited budget.

In fall 2010, U.S. Geological Survey (USGS) researcher Steve Corsi approached DNR's and UW-Extension's Water Action Volunteers (WAV) Stream Monitoring Program about developing a monitoring program that would enable volunteers to assist in studying the impacts of road salt on urban streams.

Thursday, January 12, 2012

Winter speed limits can reduce the need for salt

Demand for road salt could be reduced if we found alternate ways to improve winter driving safety.  One obvious way is to reduce winter driving speeds.  Surveys show that the typical driver understands reducing speed improves safety, yet they are unwilling to reduce speed.

Winter speed limits are becoming standard practice on some highways in northern states, and dynamic message signs are a means to achieve this.  The signs flash speed limits, that change in response to weather.

Statistics show that during winter, accident rates do go up.  But not all accidents in winter are due to icy roads.  Many of these accidents would have occurred anyway, without snow on the roads.  So, there's a tendency for the public to believe that all accidents in winter are due to ice.  This creates an unreasonably high demand for salt.

The demand for salt can be managed by opinion surveys, public education, and the promotion of alternate pathways to winter highway safety--such as reduced speed limits and a requirement for snow tires.

A requirement for snow tires can reduce the demand for salt

There are two things drivers can do to make winter driving safer: Reduce speed, and use snow tires.  Yet the use of snow tires has declined--perhaps because motorists are not aware that modern "all weather" tires are not very effective in snow.

The public demands salt on the road because it makes them feel safer, and provides a better driving experience--meaning they can go faster.  In other words, the typical driver is unwilling to drive more slowly or to use snow tires--and instead asks the government to assume responsibility for safety.

If responsibility for safety can be transferred back to the driver, then there will be less demand for salt from the public.  This transfer can be accomplished through laws requiring snow tires in winter, lower insurance rates for cars with snow tires, and lower speed limits in winter.  Public education is also necessary.

Wednesday, December 14, 2011

The idea that road salt improves safety--is a myth

Overuse of road salt is driven by the idea that salt clears the pavement and makes driving safer.  Basically, the public demands bare pavement, and City officials feel they must deliver, or suffer outrage from the public.

"...Perhaps surprisingly, health care and insurance costs arising from winter accidents increase with the use of road salts. Better winter driving conditions encourage increased traffic speeds with the attendant impact that, when faced with severe weather or where road clearing has been compromised by inclement weather, accidents increase on a stretch of highway."  p. 27

"...A study by the Insurance Corporation of British Columbia found that snow and ice-related accidents decreased seven percent (over the 10-year average) in the City of Kamloops following the introduction of new road salts techniques (anti-icing and pre-wetting) while also reducing the City’s snow and ice removal costs." p. 31

Beneath our radar, what's happening is that the Public is transferring responsibility for safe driving to the City.  Once the pavement is mostly clear, drivers resume normal speeds, which aren't really safe in the winter.  Then they blame the City if they have an accident.

What's needed is getting the public to accept responsibility for safety.  This report from Ontario presents a number of ways this can be accomplished--such as requiring snow tires for winter driving, or enforcing lower winter speed limits.