How Laws are Made in Minnesota, Part 2

Sometime around April 1, 2008 the Minnesota Pollution Control Agency (MPCA) learned that some storm water detention pond sediments in the Twin Cities area contained a class of compounds called polycyclic aromatic hydrocarbons (PAHs). As indicated in Part 1 of “How Laws are Made in Minnesota,” some MPCA staff had identified refined coal tar-based pavement sealers (RTS) as a possible source based on claims made in a paper published by several U.S. Geological Survey (USGS) and City of Austin (CoA), Texas staff scientists.

A well-known environment consulting company, Earth Tech, was retained to look into the issue and, in June 2008, issued a report that concluded:

Mahler, 2005 [the USGS and CoA paper] studied PAH concentrations in coal tar sealants used for asphalt. During this study, a signature or ratio of PAH components specific to pavement sealers was not identified…Thus, fingerprint or signature analyses can not yet be used to separate sealant source PAHs from various other urban sources yielding heavy PAHs… Scoggins [a CoA staff scientist] et al. (2007), tried to identify the sources of PAHs in Austin, Texas, area stream using ratio methods, but were unsuccessful, having found no significant clustering of field data with known source data. [Earth Tech (2008). Identification of Sources of PAHs in Urban Stormwater. Prepared for MPCA. p. 34.]

 In other words, Earth Tech was unable to make a connection between the PAHs in stormwater pond sediments and RTS. Also available at the time was a critical comment about the USGS and CoA paper that had been published in 2006, in which it was which observed:


1. With regard to the PAH ratio analysis, we could not identify the source of the values presented for stream sediment samples, and the values that we could identify from the City of Austin appear to contradict the interpretation developed by the [USGS and CoA] authors. And

2. With regard to the mass balance analysis, we could not identify the source for values from one watershed, the values presented for the other watersheds do not appear to match those from the cited sources, and the previously published values suggest the relative contribution of PAHs from parking lot sources is substantially less than the “majority” source suggested by the authors. [DeMott & Gauthier (2006)]




On July 8, 2008, MPCA’s Keith Cherryholmes wrote an email to MPCA staff scientist, Dr. Judy Crane:


Would you have a little time to look at the re-write of the first PAH report you reviewed for us. Bruce Wilson does not think it really makes a care for coal tar-based sealants as being the source of PAHs in stormwater sediments.

  On November 20, in an email that appears to be from Dale Thompson, there is this:


...As I understand it, EPA is prepared to release a policy statement and a fact sheet on sealing of asphalt which contain strong statements about the environmental harm and a strong recommendation to stop the practice. At the moment they are dealing with strong industry opposition to the position …

  Problem is, the industry did not begin to re-organize PCTC to be able to address these issues until August 2008, and was in no position to have voiced even weak opposition at the time. Also, emails included in MPCA’s FOIA response only include correspondence with a junior scientist in EPA’s Chesapeake Bay Program Office. There is no indication of communication with any EPA policy-setting arm, and certainly no hint that any of MPCA’s staff was concerned in any way about communicating with industry.

Shortly thereafter, MPCA decided to recommend a ban on RTS in the State of Minnesota.  On November 26, 2008, an MPCA staff scientist, Dr. Judy Crane, wrote the following in an email to her superior, Dale Thompson:


I think there is more than enough justification with the EPA’s upcoming policy statement and with Peter Van Metre [a USGS scientist] et al.’s recent ES&T [a science journal, Environmental Science & Technology] publication for our pollution prevention folks to work towards supporting a ban on coal-tar based sealants in Minnesota. Do you anticipate this happening this FY [fiscal year]?

Thus, without regard to the findings of MPCA’s nationally respected consultant, without consideration of published studies that contradicted claims made in the USGS and CoA paper and without communicating with RTS businesses, but with assurances from an unidentified source that EPA was about to issue a “strong recommendation,” MPCA began a quest to ban RTS in Minnesota. 

In the next column, MPCA offers money to Minnesota cities that ban RTS.