Editor’s Comments: Trickle-Down From the CGP

As you’re no doubt aware, EPA released its new five-year construction general permit in February, replacing the just-expired previous permit. This in itself is nothing out of the ordinary–except that the provisions of the new permit are, for those who’ve been watching EPA’s developing rules for construction sites over the last few years, somewhat unexpected. The question now is what the new CGP will mean for the stormwater industry and for water quality in general.

EPA has been developing construction effluent guidelines–the last version published in 2009–that contained a numeric turbidity limit, along with other erosion and sediment control provisions. In the 2009 effluent guidelines, that numeric limit was 280 nephelometric turbidity units (NTUs), and many of us expected this limit to be part of the new CGP. But early this year, after being challenged by the National Association of Home Builders and others, EPA stayed the 280-NTU limit, citing an error in the way the number had been calculated. In January the agency asked for further input not only on the 280-NTU limit but also on the technologies needed to achieve it, and the whole issue is still under review.

Although this new national CGP applies directly only to a few states and to US territories and tribal lands, most states look to it to determine the provisions of their own construction general permits. A few states have more stringent permits than EPA’s and had already been including numeric limits; however, the lack of a numeric limit in EPA’s permit makes it less likely that other states will now add such a limit to their own.

Already, at least one state has dropped some of its existing numeric effluent limits. In December 2011, a California superior court ruled that the state’s Water Resources Control Board must set aside the portions of the state’s general construction permit that impose a numeric effluent limitation for turbidity or pH on Risk Level 3 construction project sites. The ruling said the board must “refrain from adopting, implementing, or enforcing” any such limit until one of two things happened: Either the numeric limit was “developed on the basis of best conventional pollution control technology” as assessed according to the Clean Water Act, or the US EPA promulgated a numeric effluent limit and incorporated it into the construction general permit. Since neither of these things happened, it seems likely that those numeric limits are gone for good in California.

One EPA official, Greg Schaner of the Office of Wastewater Management, speaking at the annual conference of the International Erosion Control Association just days after the CGP was issued, said that even if EPA does issue a new numeric effluent limit before this new five-year permit expires, the permit will not be reopened to include it; it would instead wait until the next CGP.

EPA’s new permit does incorporate many other aspects of the 2009 construction effluent guidelines, including those relating to natural buffers, sediment discharge controls, soil stabilization, and guidelines on the use of treatment chemicals to reduce turbidity.

You can find a PDF of the complete permit at www.epa.gov/npdes/pubs/cgp2012_finalpermit.pdf.