EPA's Proposed Effluent Limitation Guidelines Are Here

EPA announced last week the long-awaited proposed effluent guidelines for construction sites and released a pre-publication version (you can see it here). Once the guidelines are published in the Federal Register, comments are due to EPA within 90 days. For all of us who work in the erosion and sediment control field and whose work might be affected, it’s worth taking a look at the full document. But here, in a nutshell, are some of the highlights. The full title of the proposed rule is “Effluent Limitations Guidelines and Standards for the Construction and Development Point Source Category,” and its intent is to tighten controls on discharges from construction sites by establishing technology-based effluent limits and performance standards. First, the rule calls for non-numeric limitations that require all dischargers to provide erosion and sediment control BMPs, which are specified in the rule. Additionally, sites of 10 acres or more would need to have a sediment basin, or something that controls sediment to the same extent. For certain sites, though—“large sites located in areas of high rainfall energy and with soils with significant clay content”—EPA proposes a numeric turbidity limit of 13 NTUs. Because this level is hard to achieve with fine silty and clay soils by settling alone, EPA says such sites will probably need to use active treatment systems, such as the addition of chitosan or other polymers to promote flocculation, followed by some type of filtration. It also mentions electrocoagulation as a technology capable of reducing turbidity levels. The sites subject to this 13-NTU limit would include those of 30 acres or more with an average soil clay content of more than 10% and a rainfall erosivity factor (the “R” factor from the Revised Universal Soil Loss Equation) of 50 or greater. (If you view the complete document, see Option 2 for more details on which sites would be subject to the numeric limit and what other possibilities EPA considered.) In areas for which the R factor hasn’t been calculated, total annual rainfall will be used as a criterion. (Discharge from rainfall exceeding the local 2-year, 24-hour storm, however, would be exempt from the limit.The proposal addresses the concern that polymers might be overused at some sites, and that discharges from those sites would be toxic. It judges the likelihood of this problem occurring to be low, however, citing the widespread use of polymers in wastewater treatment facilities. EPA is also asking for comment on setting a turbidity limit in the range of 50 to 150 NTUs, based on passive treatment. See the document for a discussion of this option. EPA says the rule will cost about $1.9 billion per year, and the document includes a detailed discussion of how it arrived at this figure.http://www.epa.gov/waterscience/guide/construction/