Numeric Turbidity Limits: Your Comments Wanted

Jan. 24, 2012
4 min read

Early this year there was a new development in EPA’s ongoing work toward a numeric turbidity limit for discharge from construction sites. There’s still a chance for you to participate and offer comments on the numeric limit, as well as on the technologies surrounding its implementation. You have until March 5 to get your comments to EPA.

Some background: In late 2009, EPA published its effluent limitations guidelines for the construction and development industry, which set a limit of 280 nephelometric turbidity units (NTUs) on discharge from most construction sites of 10 acres or larger. (This was down from just 13 NTUs in a draft of the guidelines issued in 2008; EPA took public comments on the draft into account when formulating the rule issued in 2009.) The guidelines also called for other erosion and sediment control measures, such as using perimeter controls and minimizing the amount of land disturbed at one time, but for many in the industry the numeric limit was the key part of the rule, and many felt that 280 NTUs was still an unreachably low–and prohibitively expensive–number.

After the guidelines were issued, the Small Business Administration and the National Association of Home Builders petitioned for EPA to reconsider the numeric limit, based on a potential error in the way that number had been calculated. EPA reexamined its data and proposed, in a notice in the Federal Register on November 5, 2010, to stay the 280-NTU limit until it could be reassessed. The agency formally stayed the limit in January 2011, saying it has miscalculated the data and that a revised limit would be published at a later date.

On January 3, 2012, EPA published a notice in the Federal Register asking for additional data on several issues related to the numeric limit: sample collection, cold-weather considerations, applicability of the limit to certain types of construction, and others. As usual, there is a 60-day public comment period. EPA will be accepting public comments on these issues until March 5.

The notice in the Federal Register, available at www.gpo.gov/fdsys/pkg/FR-2012-01-03/html/2011-33661.htm, is well worth reading. It’s about 12 pages long and includes information about how the original 280-NTU limit was calculated, based largely on data from eight different construction sites in three states, and why it is now being reconsidered. It also contains summaries of the technologies needed to meet a specific numeric limit, defines what the agency means by “passive treatment,” includes a discussion of the limitations of sampling equipment and practices, and addresses comments EPA received regarding the potential toxicity of chemicals used in treatment systems to reduce turbidity. It also discusses the issue of small construction sites and certain other types of construction like electric utility transmission lines. If you’re considering providing comments to EPA, or if you just want to see what the issues under consideration are at this point, it’s worth the time to read through the notice.

If you didn’t submit comments on earlier versions of the numeric effluent limit guidelines–or if you did but have new information or thoughts on the process–this is your chance. Although the agency doesn’t always come up with a solution that satisfies everyone, and although many of the comments it receives on any given issue contradict each other, EPA has demonstrated over the last few years that it is listening to the comments and taking them into account.

Many states are waiting on EPA’s final decision to see whether they’ll be incorporating numeric limits into their own construction general permits. This is an important ruling in the stormwater industry that will affect how we do business and what our priorities are for years to come, so if you have something to contribute, now’s the time. You can submit comments online by following the instructions at www.regulations.gov.

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