Field Test for Coal Tar Sealant Determination

Funny that this simple test has been the source of a lot of consternation, much of which will have to wait for a more thorough re-telling.  Suffice it to say, that my colleague, who will want to remain anonymous, and I knew the importance of finding a repeatable field test.  We found out about the time of Austin passing its sealant ban, that there was no easy way to figure this out published.   

After some trial and error, we have come up with a pretty reliable and definitely cheap test.  The USGS successfully used this on the Indoor Dust Study (2010) to differentiate between coal tar sealed and asphalt sealed parking lots.  

Industry "Study" Says No Effect in Austin From Sealant Ban

Wow, with a preconceived outcome and limited data it is little wonder what the results would be.

Here are some very obvious thoughts about this industry sponsored study.

To paraphrase Lyndon Johnson, environmental stewardship is a journey of a thousand miles and it must be taken one step at a time.  The Austin coal tar sealant ban has been responsible for the reduction of about 1 million pounds of PAHs from being put into the environment since the start 2006.  That provides environmental and public health benefits, whether measurable with our means and methods at this time or not.
The title of the "PAH fingerprint" news release is misleading at best.  When someone says "years after" that implies a long time, but it is just 2 years after the ban was passed!  While every chemical is different, the USGS researchers recently mentioned to the Springfield City Council that if often takes a decade for receiving sediments to begin to show a reduction after the elimination of the source chemical, like lead in gasoline.

This study is the ongoing industry dodge of the fundamental question at hand: if coal tar sealants are very high in PAHs, where does it go when it is worn or scraped off?  How does it go from 1000's of times the effects concentration on the pavement, to no effects in the air or downstream?  Study after study have shown that it does come off at potent, toxic levels.

Pavement sealants wear off at a low rate per year (that is unless you scrape them off with a snowplow).  A 2007 Austin study, as well as the recent publication by the University of New Hampshire, agree that the wearoff of these products is year after year consistently less than 10%.  So you could stop sealing with coal tar or anything else and have a consistent load to creeks for at least 10 years!  And they reasonably thought anyone expected to see a measurable difference in 2 years!  The City of Austin has been doing robust sampling of sediments throughout Austin and is expected to prepare a study of its findings in 2011.

As the director of our state environmental agency said, the Austin ban is based upon the following undisputed facts (see youtube video at http://www.youtube.com/watch?v=Fb6AWwMb4zM):

• PAHs are pollutants.
• PAHs are in coal tar sealants.
• PAHs are a pollutant of concern in the City of Austin (and now shown throughout the country in the 40 Lakes study).
• State agency found that creek contamination in one location was from coal tar pavement sealants.
• State agency found that the Austin ban was reasonable method to control one source of PAHs in Austin.

I hope this brings some clarity to this publication.

Coal Tar Sealant Dominates PAH Pollution Across US

The USGS published their research paper about the contribution of coal tar sealants to 40 lakes across the country.  Key findings were:

• Coal tar sealants are the dominant source of PAHs in urban lakes.
• On average coal tar sealants represent half of the source of PAHs in these locations.

These findings are also important because of the claim by some that the research done to date is too geographically isolated to apply to the nation as a whole.  This study, plus the USGS parking lot dust study, the University of New Hampshire sealant research, and the New York Academy of Sciences work, gives ample evidence for the problem of coal tar containing pavement sealants in much of the United States.

I put together a nifty little Google map that allows you to zoom into the actual location if you are interested in seeing the aerial photos of the locations.  The "pins" on the maps are color-coded that shows the relative concentration of the PAHs found.  You can see the geographical range where this is a problem.  Check it out and let me know what you think. 


Double-click to view 40 Lakes Sampled by USGS for Coal Tar Sealants & PAH in a larger map