This season, Clean Ocean Action is offering tips on how to green your holiday. Here is the eighth of twelve in COA's '12 Days of Green Giving' series.
By: Sean Dixon, Coastal Policy Attorney
Picture this (or look outside) – it’s cold, dark, and snowing. Maybe it is also sleeting, or both. Now, imagine you have to head out to work, or welcome some friends over for dinner. The road are icy and your sidewalk treacherous. What’s your solution? Spread some salt! Call the salt trucks! Melt that ice and say hello to easy driving and safe steps. Right?
By: Sean Dixon, Coastal Policy Attorney
Picture this (or look outside) – it’s cold, dark, and snowing. Maybe it is also sleeting, or both. Now, imagine you have to head out to work, or welcome some friends over for dinner. The road are icy and your sidewalk treacherous. What’s your solution? Spread some salt! Call the salt trucks! Melt that ice and say hello to easy driving and safe steps. Right?
Wrong.
The way rock salt for melting ice works is that the salts
themselves reduce the melting point of water – so instead of 32 degrees, water
around the salt crystals will melt at a lower temperature (like 25
degrees). If it’s -20 degrees, well,
then you probably don’t want to go out anyways, and your normal rock salt won’t
work. During the summer, in most parts
of the urban landscape, over-use of fertilizers can be what leads to
significant local water quality problems.
Fertilizers can also be bad for your soil and for your pets. Rock salt is the winter version of fertilizer,
and can cause a host of problems:
First, rock salt is
bad for your pets.
The crystals can
get ingested (they stick to paws, fur to be eaten later indoors, or eaten while
in the ice and snow) and can lead to burned skin (apparently, the crystals can
reach over 150 degrees!). It’s also bad
for other wild animals – in natural ecosystems, salt is a rare commodity and
deposits of salt, called “salt licks,” are the coffee shops of the animal
world. Road salt in many places can attract
animals to roadways, endangering both the wildlife and drivers.
Second, it can be really bad for drinking water and water
quality.
According to a
Stormwater journal article, the
New York City watershed (from which all NYC’ers get their tap water), there are
“approximately 6,000 mi. of paved roadways in the watersheds, where road-salt
application ranges from 37 to 298 tons/lane-mi./yr.” That’s upwards of 300 tons per mile per
lane deposited through the watershed!
The USEPA
warns that salt in drinking water can impair water quality to the point
where it’s dangerous for aquatic life, corrodes drinking water infrastructure,
and endangers human health.
In 2010, in New Jersey, a Times of Trenton article that “Road salt already has
caused problems in some drinking-water supplies in Bergen and Morris
counties. Mahwah stopped using one of
its 12 municipal wells years ago because of a high sodium content officials
believe came from road salt dumped on Route 17.” According to the article, the state DEP thinks that “up to 60 percent of road salt
infiltrates ground water.”
Third, it’s bad for soils.
In
some cases, soils have been tested at double the levels considered too high
for normal bacteria functions. Without
healthy bacteria, soils become dirt, dust, and then run off into waters –
losses for agriculture, parks, habitat, and downstream water quality. Salt in soils is also bad for plants – inhibiting
long-term growth, causes chlorine
toxicity in leaves, and creates micro-drought
conditions.
Fourth, it’s really bad for our infrastructure.
Most people from wintry areas know that salt
is bad for your car (corroding the undercarriage), but it’s also really bad for
concrete
and pavement. Basically, the way it
works is that your melted ice becomes really, really salty water – and that
salty water (at the microscopic scale) enters
micro-holes in concrete (concrete is full of these mini-holes, called
pores). Once inside the concrete, that
salty water re-freezes (usually at night when temperatures drop). Frozen salt water expands and creates
salt particles – both of which are bad for your sidewalk, causing
pits and cracks.
According
to an August 2010 USEPA factsheet, over 15 million tons of rock salt are
spread on our pavement, sidewalks, and parking lots each year. What’s to be done?
Fortunately, there are a few solutions, though as one blog puts it,
“you probably won’t like to hear” the best solution…shovel more!
Ideally, the best solutions are simple: shovel snow off your
driveway so that it doesn't melt and freeze into dangerous ice, don’t use rock
salt (or any salt), and put boots on your pets if you’re walking on other
people’s sidewalks where there is rock salt.
This keeps your pets, your soils, your drinking water, you, and your
concrete happy and healthy!
To avoid slipping, you can use cat litter, sand, or sawdust
to coat your icy pavement, or build your walkways out of gravel or rocks –
avoiding the problem altogether.
Finally, one amazingly cool (or warm?) solution is also an
energy efficiency one: use excess heat from power plants or geothermal heat to
melt snow and ice!
Heated sidewalks and driveways are all the rage in many
colder cities and towns. In Holland, Ohio, in
1988, the city’s leaders (with a substantial private donation) converted
all of their downtown’s public walkways to heated-sidewalks by piping hot
water from the nearby power plant through pipes under the pavement. The
call this the “snowmelt” system, and claim it can melt 1 inch of snow per hour
at 15-20 degrees F. This is hot
water that would have to be cooled anyways, so the town gets an added
benefit! Over
120 miles of tubes keep the sidewalks walkable all winter long. Homes and small businesses can do this too –
and can tie it into geothermal systems to use the ground’s natural warmth to
keep the surfaces ice-free!
