On December 1, 2009, U.S. EPA published effluent limitations guidelines and new source performance standards to control the discharge of pollutants from construction sites. U.S. EPA expects that the New Stormwater Rule1 will reduce the amount of sediment discharged from construction sites by about 4 billion pounds each year. Importantly, the U.S. EPA also estimated the annual cost to comply with the New Stormwater Rule to be approximately $953 million after the rule has been fully implemented.2

The Clean Water Act (CWA) provides that "the discharge of any pollutant by any person shall be unlawful," except in compliance with other provisions of the statute.3 In 1987, the Water Quality Act of 1987 amended the CWA, requiring the implementation of a comprehensive program for addressing stormwater discharges.4 As a result, U.S. EPA developed its National Pollutant Discharge Elimination System (NPDES) stormwater program. The NPDES stormwater program currently requires site operators who will be engaged in clearing, grading and excavating activities that disturb one acre or more, including smaller sites in a larger common plan of development or sale, to obtain coverage under an NPDES permit for their stormwater discharges.

Most states are authorized by U.S. EPA to implement their own stormwater NPDES permitting program. As a result, U.S. EPA is requiring states to implement the effluent limitations guidelines and new source performance standards discussed within this article.5 For example, the State of Ohio's stormwater NPDES permitting program, as administered by Ohio EPA, provides two options for obtaining authorization to discharge under this permitting program. An operator can obtain coverage under the General Permit for Stormwater Discharges Associated with Construction Activity (General Permit) by submitting his Notice of Intent to Ohio EPA and complying with the terms of the General Permit. In the alternative, an operator may obtain coverage by applying for an individual NPDES stormwater permit that is specific to the operator's site. For those states that are authorized to implement their own NPDES stormwater program, U.S. EPA is requesting the state permitting authority to include the New Stormwater Rule requirements in the state's next construction general permit issued after the effective date of this regulation.

The stormwater NPDES permitting requirements impact many parties involved with the construction industry. For example, the permitting requirements may affect operators who are engaged in residential, nonresidential, industrial, commercial and institutional building construction activities.6 The stormwater NPDES permiting requirements may also affect those operators working in heavy and civil engineering construction, including utility systems construction, land subdivisions, highway, and street and bridge construction.

Numeric Effluent Limitation and Monitoring Requirements

Until recently, stormwater permits did not contain numeric effluent limitations. Before promulgating the New Stormwater Rule, U.S. EPA completed an Environmental Assessment which evaluated the environmental impacts from stormwater discharges associated with construction activity and concluded, in part, that the most prominent and widespread pollutant discharges from construction sites are turbidity and sediment.7 As a result, the New Stormwater Rule will require certain operators to monitor turbidity in stormwater discharges from their construction sites. Further, the New Stormwater Rule establishes a numeric limit for turbidity of discharge from the construction site. The site's stormwater discharge must be below the daily maximum value of 280 Nephelometric turbidity units (NTU).

This numeric limitation for turbidity requirement only applies to construction sites when the total disturbed areas is 10 or more acres at one time. When stabilization of disturbed areas reduces the amount of total disturbances to less than 10 acres, the numeric limitation no longer applies. U.S. EPA believes that this provision creates "an incentive for large sites to stabilize disturbed areas as quickly as possible, thereby reducing the turbidity in stormwater discharges from the site."8

U.S. EPA has allowed for the New Stormwater Rule requirements to be phased into the stormwater NPDES permitting programs over the next four years. In that regard, the numeric effluent limitation and the associated monitoring requirements for sites with 20 or more acres of land disturbed at one time will become applicable to discharges associated with construction activity on August 1, 2011. The numeric limitation and associated monitoring requirements for sites with 10 or more acres of land disturbed at one time will become applicable to discharges associated with construction activity on February 2, 2014.

Below are additional facts regarding the application of the numeric limitation for turbidity:

  • The 10-acre disturbance threshold includes non-contiguous land disturbances that take place at the same time and are part of a larger common plan of development or sale.
  • Small construction activities occurring at the same time, but in separate and distinct areas of a project site, which together disturb 10 or more acres of land, are also required to meeting the monitoring and effluent limitation requirements.
  • U.S. EPA intends to provide monitoring guidance with a technical resource guide to permit writers, e.g. Ohio EPA, in establishing monitoring requirements in their general and individual construction stormwater permits.
  • The numeric effluent limitation for turbidity is a daily maximum limitation, meaning that permittees may sample the turbidity in their discharges multiple times over the course of a day and the average of all measures may not exceed the limitation.
  • U.S. EPA expects the permit writers to require, at a minimum, three samples per day at each discharge point while a discharge is occurring.
  • The numeric limitation applies to all discharges from the construction site except on days when the total precipitation during the day exceeds the local 2-year, 24-hour storm event.

Erosion, Sediment Control and Soil Stabilization Requirements

This new rule also establishes general erosion and sedimentation control requirements that will apply to all those operators seeking coverage under the stormwater NPDES program (non-numeric requirements). The non-numeric requirements become applicable within 60 days after the final rule is published in the Federal Register, which was February 1, 2010. The non-numeric requirements include provisions related to designing and installing erosion and sediment controls, soil stabilization, dewatering, pollution prevision measures, prohibited discharges and requirements related to surface outlets.9

Implementation of the New Stormwater Rule By Ohio EPA

Generally, Ohio EPA already includes these non-numeric requirements in its current stormwater NPDES permitting program. While Ohio EPA currently requires stabilization techniques to be implemented at a site when construction activity will not resume for a period exceeding 21 calendar days, the New Stormwater Rule requires that stabilization techniques are implemented when construction activity will not resume for a period exceeding 14 calendar days.

Ohio EPA intends to incorporate both the turbidity numeric effluent requirement and the 14 day non-numeric stabilization requirement into future construction stormwater NPDES permits that Ohio EPA issues. For operators seeking coverage under Ohio's General permit, these requirements will be spelled out in the renewal of the General Permit which Ohio EPA expects to issue on April 21, 2013. For operators seeking coverage for construction activity under Ohio's General permit for the Big Darby Watershed (Darby Watershed General Permit), these requirements, along with the deadlines that are specifically applicable to the numeric turbidity limitation and monitoring requirements, will be provided in the renewal of the Darby Watershed General Permit, which Ohio EPA expects to issue on October 27, 2011.