Tuesday, October 28, 2008

Liquid de-icers on your driveway...

We get e-mail questions every day and I’m guessing that the answers include information that you didn’t know either – so we’re going to post some of those e mails and the responses here so you can weigh in.

This October 23rd e-mail from a Leavenworth resident went to North Central Region Communications Director Jeff Adamson in Wenatchee:
(Question) What kinds of liquid de-icers should I buy to use on my private driveway which is connected to Highway 2? The state snowplows leave a build up of snow when they plow and I have had a hard time deciding what to do about getting rid of this accumulation. I would like to know what brand of de-icer to buy that would be safe to use for our environment and still get rid of the snow on my driveway.

(Response) Typically, private citizens don't use commercial liquid anti icers for the same reason that they aren't used in parking lots - most are sticky (because of the anti corrosion agents in them) and make a mess out of carpets (The Bon Marche’ opened a new store in Denver a few years ago and used liquid anti icer in the parking lot and had to replace 50,000 square feet of carpet, the week after their grand opening...)

That being said - you can make your own (not sticky) simply by mixing the crystal de icer you can buy at any hardware store with hot water. I need to point out that we only use liquid as a pre-treatment - not to melt snow that's already there. Liquid is "anti icer" and solids (crystals) are de-icers. Apply the liquid before there's any frost, snow or ice on your driveway and when it comes, the water crystals won't bond to the pavement so when you shovel off the accumulation, your blade gets all the way down to the pavement and your driveway is bare and wet when you're done instead of still covered with a layer of hard packed snow or ice.

Once the snow has started falling and is accumulating on the roadway, we switch to solid (crystal) salt which is wetted with anti corrosive liquid. That accomplishes two things. One- it makes the rock salt stick where we put it, so the next truck through the zone doesn't blow it all onto the shoulder, and second, the wetted salt meets the state standard of 70% less corrosive than untreated rock salt. For residential purposes - you probably don't drive fast enough on your driveway to cause whatever you put on it to create a corrosion issue or a "blow off" issue - so pre wetting your “home” rock salt isn't necessary.

From an environmental standpoint, the amount of salt you are likely to use will be diluted with melted snow to nearly undetectable levels by the time it goes through the stormwater system and gets to the river. That's not to say, due to the topography of your driveway, that you might have a spot in your yard or garden where your driveway run off accumulates, that could produce some yellow spots in your grass next spring.

Finally, using chemicals to melt the snowplow curl at the end of a driveway is not very efficient in that it requires a lot of it. Spokane is in an environmental zone where the city and county are not allowed to use sand because when it dries, it becomes dust and violates air quality standards. Spokane uses liquid as a deicer and uses more of it than the entire rest of the state combined. We apply liquid as a pre treatment at the rate of 15 to 30 gallons per lane mile (depending on type of road surface and temperature). As a deicer, Spokane sometimes applies it at the rate of 100 gallons per lane mile. If you've driven there, you will note that at those levels, applied winter after winter, the practice has caused deterioration of both pavement and curbs on local streets.
I would recommend that you shovel or plow the curl at the end of your driveway instead of trying to chemically melt it (although I would certainly pre-treat that area with a liquid mixture so when the accumulation comes, it's easier to remove.)


Grant said...

Thanks for the tips on the liquid anti-icers Jeremy. I did not know that and will make sure to pass along the anecdote about The Bon to others thinking about it.

Since salt seems to be the best answer, where can regular consumers obtain rock salt in the quantities needed?

Jeremy Bertrand said...

Because I live in Olympia this isn't something I have much experience with, however, Jeff, a WSDOT employee who lives in Wenatcheee says this:
Normal sized bags 10-20 lbs) are stocked at all the hardware stores. If you want the really big ones (50 lb) - go to a soft water supplier (even Sears). I live in Wenatchee and have never used up a whole ten pound bag in a winter (I usually have enough left over to keep my ice cream maker functioning all summer...)

Anonymous said...

try Bare Ground (www.bareground.com). It's supposed to pre-treat and make taking care of the pavement easier.