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Phyllis Harden

Legislative & Special Projects, Pine Bluff Sand & Gravel
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Final Word on Construction Stormwater Management: EPA Eliminates Numeric Turbidity Limits, Monitoring Requirements from Federal Law

April 1, 2014

After a Decade of Back-and-Forth, Non-numeric BMPs Reign

On March 6, 2014, the U.S. Environmental Protection Agency (EPA) published long-awaited final amendments to its highly contested stormwater management rule, promulgated in late 2009.  The amendments withdraw the nationwide numeric limit on the allowable level of dirt in stormwater runoff from active construction sites. They also revise some of the non-numeric or Best Management Practice (BMP) requirements and establish a new key definition for the term “infeasible,” as it relates to the implementation of those BMP-control requirements. This action is in accordance with a settlement agreement reached with construction and industrial trade groups to resolve litigation on the 2009 rule. This article lays out EPA’s “final word” on the “Effluent Limitations Guidelines and Standards for the Construction and Development Point Source Category” (C&D ELG or stormwater management) rule, explains how the rule applies to contractors and reflects on the government’s effort to dictate exactly how much dirt is allowed in stormwater that runs across construction sites.

Numeric Turbidity Limit Eliminated

After more than a decade of trying to force a strict discharge limit and sampling requirements into all (federal and state) construction stormwater permits, EPA has finally deleted the nationwide numeric turbidity limit from the stormwater management rule, codified at 40 CFR Part 450.22.  The limit has been on “hold” since January 2011, following the initiation of several lawsuits and the agency’s admission of flawed data.  EPA’s justification for eliminating the limit once and for all is that it would discourage the adoption of the agency’s preferred “green infrastructure” techniques to retain stormwater. “[M]eeting a numeric standard may require installation of a sediment basin or other impoundments on certain sites, which may be a disincentive to installing distributed stormwater controls,” the preamble to the final amendments states. 

Status of the Non-numeric BMP Requirements

The non-numeric requirements of the stormwater management rule (codified at 40 CFR 450.21 and in effect since February 2010) include a range of prescriptive measures and practices that call for owners and operators of permitted construction sites to:

  • Implement erosion and sediment controls;
  • Stabilize soils;
  • Manage dewatering activities;
  • Implement pollution prevention measures;
  • Provide and maintain buffers around surface waters;
  • Prohibit certain discharges, such as motor fuel and concrete washout; and
  • Utilize surface outlets for discharges from basins and impoundments.

The final amendments provide additional detail regarding requirements to control erosion caused by discharges, such as where buffers are required, and soil stabilization, preservation of topsoil and pollution prevention measures. EPA also added a defined term “infeasible,” which means “not technologically possible, or not economically practicable and achievable in light best industry practices.”  EPA said it made this change because several of the rule requirements allow exceptions in cases where a particular practice is infeasible. Addition of a definition of infeasible will clarify for the regulated community and for permitting authorities when it is appropriate to apply these exceptions. 

The final amendments to the stormwater management rule will take effect on May 5, 2014.

EPA’s website has been updated accordingly. AGC strongly supports EPA’s decision to delete the nationwide numeric turbidity limit from the federal stormwater management rule. In addition, AGC finds that the revised non-numeric BMP provisions will provide additional clarity, efficiency, and improve the existing C&D ELG rule.  AGC also supports the addition of the defined term “infeasible,” which recognizes the potential that site-specific conditions may pose technically impossible or cost-prohibitive hurdles.  

Implementation & Applicability to Contractors

The C&D ELG rule directly applies to individual construction sites when its provisions are added into individual and general stormwater permits that the National Pollutant Discharges Elimination System (NPDES) regulations require. States are required by EPA to incorporate the C&D ELG provisions into their permits the next time they are renewed (or earlier if the states so choose).  States began the cycle of incorporating the C&D ELG rule into their construction general permits (CGP) in early 2010; this has been happening on a piecemeal basis as permits come up for renewal.  Currently, most states and EPA already have implemented the non-numeric BMP requirements (from the 2009 version of the rule).  AGC expects that EPA will modify its 2012 CGP and CGP guidance as appropriate to reflect the recent amendments; NPDES-authorized states are likely to follow suit  With regard to numeric limits, AGC took significant steps to ensure that EPA’s 2012 Construction General Permit (which serves as a national model) did not include any limits or discharge monitoring requirements. For states that opted to include numeric limits, like Washington State, they may be influenced to now remove or revise the limits in their permits, given their elimination by federal EPA regulators. (Note that most states that have reissued their CGPs over the last four years have done so without numeric limits and monitoring requirements, because of EPA’s direct final rule that stayed the numeric limit indefinitely – see below.) Ultimately, it may take five more years for the final amendments to be fully implemented across the nation.  AGC chapters and members should be vigilant in monitoring and participating in their states’ efforts to revise their general permits and take steps to mitigate any increased engineering, labor, and materials cost (associated with the non-numeric BMP requirements) wherever possible. Generally, federal law requires the “operators” of any construction site that will disturb one acre or more of land to obtain authorization to discharge stormwater under an NPDES construction stormwater permit. A failure to apply for stormwater permit coverage or to comply with the terms and conditions of a construction general permit can result in penalties of up to $37,500 per day per violation.  Click here for more information.


EPA appears to leave the door open to a numeric limit in future actions, stating in its final amendments that it “has reserved these [regulatory sections] should EPA decide to propose and promulgate additional effluent limitation guidelines and monitoring requirements in future rulemaking.” EPA recognizes that “additional data” collection would likely be necessary in order to inform any establishment of numeric discharge standards and monitoring in the future.  At a meeting between AGC members and EPA staff last summer, EPA indicated that it was not currently working on a new numeric limit. For the effort to pick back up, EPA would need to collect a lot more data, as AGC’s has illustrated through detailed comments. EPA’s current datasets do not satisfy the Clean Water Act factors for establishing a numeric effluent limit. The performance data in the docket are unreliable for a variety of reasons, including, but not limited to, a deficient dataset; insufficient information as to sampling techniques, collection times, locations; failure to conform to EPA-established methods (e.g., equipment calibration, sample holding times/temperature); insufficient site or treatment method descriptions; insufficient rain event information; unexplained or inappropriate omissions of sampling data during rain events; or most often a combination of these problems. In addition, the current record does not include necessary facts that represent the full range of site and rain event conditions that occur nationally and would impact a national numeric limit.  AGC has told EPA that it should limit its data collection to a single pollutant parameter associated with erosion, and that parameter should be total suspended solids, not turbidity.

A History of the Numeric Turbidity Limit

EPA has been working for more than a decade to develop a national construction stormwater management rule, which basically sets the floor for technology-based, control requirements in NPDES permits. EPA first proposed a rule in 2002, but chose not to finalize the standards in 2004 – a decision that AGC supported in court.  After environmental groups sued, the Ninth Circuit ordered EPA to promulgate a C&D ELG.  EPA then released a proposal in November 2008 that would have required certain large construction sites to meet a numeric turbidity limit of 13 nephelometric turbidity units (NTUs).  In a final rule, published in 2009, EPA raised the numeric limit from 13 to 280 NTU.  The numeric limit was immediately challenged.  In the year that followed, industry challenges were filed in the U.S. Circuit Courts of Appeal for the Fifth, Seventh, and D.C. Circuits, a petition for administrative reconsideration was filed by the U.S. Small Business Administration, and EPA admitted that it had derived the limit from faulty data it had obtained from technology vendors. See 75 Fed. Reg. 68215 and 75 Fed. Reg. 68305 (Nov. 10, 2010).  In January 2011, a direct final rule took effect that stayed the limit indefinitely.  EPA requested new data, and AGC submitted extensive comments, but the agency never proposed a “correction rule.”  Then in December 2012, to settle the lawsuits that had been consolidated in the Seventh Circuit, EPA agreed to start a rulemaking that would remove the numeric limit and amend other provisions in its stormwater management rule. Click here to read the signed settlement document.  AGC’s submitted extensive comments to EPA in support of its proposed amendments, which included elimination of the numeric limit.  Click here for a summary of AGC’s position. While not a named party in the lawsuit, AGC has been integrally involved in EPA’s efforts to develop appropriate controls for construction site stormwater runoff for more than 15 years. As AGC has long argued, the lawsuit stressed the critical points that (1) EPA’s numeric limit would have cost industry stakeholders up to $10 billion a year in attempts to comply – and that (2) it is not possible for EPA to come up with a one-size-fits-all turbidity limit that will work across all geographic areas and soil types.   

For more information, contact AGC’s Leah Pilconis at or (703) 837-5332.

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