EPA's New Stormwater Effluent Limitation Rules

G. Fritz Hain and G. Scott Walters
June 21, 2010 — 1,216 views  
On December 1, 2009 the U.S. EPA issued a longanticipated final stormwater rule, which impacts nearly every construction and development project in the United States. EPA promulgated the rule, titled “Effluent Limitations Guidelines and Standards for the Construction and Development Point Source Category”, pursuant to authority delegated it under the federal Clean Water Act.  Now, for the first time, construction professionals are faced with an enforceable numeric limit on stormwater discharges from large construction sites, and must monitor stormwater discharge to ensure compliance with the numeric limit. The rule also requires nearly all construction sites to implement non-numeric erosion and sediment controls and pollution prevention measures. EPA was under a court ordered deadline to develop these Effluent Limitation Guidelines (“ELGs”), which took effect on February 1, 2010.
These requirements will be incorporated into the National Pollutant Discharge Elimination System (NPDES) construction general permit, presently required on all construction sites of one acre or more. Non-numeric effluent limitations remain in effect on every construction site exceeding one acre. The numeric limitation—and its associated monitoring requirements—will be phased in over four years. On August 1, 2011, construction sites disturbing 20 or more acres at one time must comply with the numeric effluent limitations. Those same requirements will apply to construction sites disturbing 10 or more acres as of February 2, 2014. The rule phases in the numeric effluent limitation over four years to allow permitting authorities adequate time to develop monitoring requirements and to allow the regulated community sufficient time to develop a full understanding of the new compliance processes.
The new rule loosely defines land disturbance to include clearing, grading, and excavation activities. It also includes any period during which affected land is generally exposed after removal of grass, rocks, pavement, and other protective ground covers. The acreage disturbed at one time triggers the numeric limitation requirement. For example, a construction site could ultimately disturb 10 or more acres, but so long as that site does not disturb 10 or more acres at one time, compliance with the numeric limitation is not required.
For many sites, the ELGs will require an additional layer of management practices and treatment above what most government programs currently require. Permitting authorities must incorporate the turbidity limitations into construction general permits, and permit holders must implement the control measures. EPA does not specify technologies to be used to meet the numeric limit. But EPA does specify the maximum daily turbidity level that may be present in a construction site’s stormwater discharges.
Whether it is the owner, developer, general contractor, or sitework contractor, the party tasked with obtaining the construction permit may select the management practicesand technologies that are best suited to site-specific conditions.
EPA projects that these regulations will reduce the amount of sediment discharged from construction sites by approximately 4 billion pounds each year, at an annual cost of about $953 million, once fully implemented.
Non-Numeric Effluent Requirements
The non-numeric requirements apply to construction activities that will disturb one acre or more, and must be incorporated into permits issued after February 1, 2010.  Many states already require such best management practices (or BMPs). The non-numeric effluent limitations include a range of erosion and sediment controls, soil stabilization requirements, and pollution prevention measures.
Erosion and Sediment Controls. Site-specific erosion and sediment control measures must be designed, installed, and maintained to control stormwater volume and velocity; minimize the amount of soil exposed, disturbed, and discharged during construction activity; provide and maintain natural buffers around surface waters; direct stormwater to vegetated areas; minimize soil compaction; and preserve topsoil.
Soil Stabilization Requirements. Permit holders must initiate soil stabilization measures immediately whenever any clearing, grading, excavating, or other earth disturbing activities have permanently ceased on any portion of the site, or if these activities temporarily cease on any portion of the site and will not resume for a period exceeding 14 calendar days. In arid, semiarid, and drought-stricken areas where initiating stabilization measures immediately may not be feasible, those measures must be initiated as soon as practical.
Pollution Prevention Measures. Pollution prevention measures should be designed, installed, and maintained to: minimize discharge of pollutants from equipment and wash waters; prohibit discharge of fuels, oils, or other pollutants used in vehicle and equipment operation; minimize exposure of on-site building materials to precipitation and stormwater; minimize discharge of pollutants from spills and implement prevention and response procedures; and prohibit wastewater from washout of concrete, stucco, paint, form release oils, curing products, and other construction materials.
Numeric Effluent Requirements
EPA’s new rule sets a numeric effluent limitation for turbidity at 280 nephelometric turbidity units (“NTU”) and requires monitoring to ensure that this limitation is met.  EPA embraced this numeric approach by reasoning that turbidity is an “indicator pollutant” which will help control the discharge of other pollutants from construction sites, such as metals and nutrients. Moreover, EPA found that turbidity may be measured economically in the field using a readily available turbidimeter. The turbidity limitation applies only to construction sites disturbing land at any one time at or above a specified acreage. From August 1, 2011 until February 1, 2014 the numeric effluent requirements apply to construction sites that will disturb 20 or more acres at any one time. As of February 2, 2014, this threshold drops to construction sites that will disturb ten or more acres at any one time.
The 280 NTU turbidity limit is expressed as a maximum daily limitation, meaning that the average daily sample may not exceed the maximum daily amount. This allows for temporary discharges of stormwater exceeding the turbidity requirement, such as discharges during an intense period of rainfall. Notably, the new rule exempts discharges resulting from a storm event that exceeds the local twoyear, 24-hour storm level.
Numeric Monitoring Requirements. Each delegated state must determine its monitoring and compliance protocols, including the frequency, location, and duration of sampling in relation to storm events. EPA offered the following glimpse into its monitoring expectations:
  • Collect a minimum of three samples per day at each discharge point while a discharge is occurring;

  • Monitor any storm event or snowmelt that generates a discharge;

  • Conduct, at a minimum, sampling during normal business hours;

  • Use a properly calibrated turbidimeter;

  • Reporting requirements are uncertain, but will likely include monthly discharge monitoring reports; and

  • EPA has suggested that permitting authorities implement notification procedures as to when the 10-acre disturbance threshold has been exceeded.
Technologies Available to Assist in Meeting the Numeric Limits.  Unlike previous rules in which EPA identified a “model” technology that had been demonstrated to meet the established limits, here EPA leaves the methodology determination to the permit holder.  Nevertheless, EPA broadly recommends certain erosion and sediment control technologies to meet the numeric limits. Builders and developers may experience a trial and error period to determine which suite of control measures will achieve the required discharge limitation on a given project. In fact, EPA cites the need to adjust, modify, and revise the new control techniques as a primary factor for delaying numeric limits by 18 months.
Recommended erosion control technologies include:
minimizing the extent of grading to reduce sediment yield; dissipating stormwater energy through diversion berms, conveyance channels, and slope drains to prevent high runoff velocities and concentrated erosive flows; vegetative stabilization; physical barriers, such as geotextiles, straw, rolled erosion control products, mulch and compost, and polymers and soil tackifiers; and periodic inspection. Typical sediment control technologies include: perimeter controls, such as filter fabric silt fences and compost filter berms; trapping devices, such as sediment traps and basins, inlet protectors, and check dams; and directing discharges from basins and channels or through silt fences or filter berms into vegetation or other buffers.
Can Builders and Developers Avoid the Numeric Limit?
The 280 NTU limit only applies when the total amount of disturbed area on the project at any one time equals or exceeds the specified acreage threshold, first 20 or more, then ten or more, acres. So, by reducing the disturbed areabelow the threshold (for example, 9.9 or 19.9 acres), the limit and its associated obligations may be avoided. This can be done throughout the entire project or during specific phases. For example, if a project initially disturbs ten or more acres, but after completion of clearing, grading, and infrastructure installation the site is stabilized before or during vertical construction, then the sampling requirements and turbidity limitations would cease to apply when the total disturbed land area falls below ten acres at one time. In all instances where the amount disturbed at any given time is greater than or equal to the specified threshold, however, the numeric limit will need to be met. EPA expects the states to determine recordkeeping and notification procedures that operators must follow to keep track of how much land is disturbed at any given time and when the limit applies.
Who Bears the Risk?
It is estimated that EPA’s new effluent limitation rule will affect more than 80,000 owners, developers, and contractors, performing both residential and commercial construction. Heavy and civil construction and engineering firms will also be impacted by the new rule. Consequently, construction professionals can expect to see increased stormwater discharge enforcement by federal, state, and local environmental regulators, including criminal and civil penalties for noncompliance, as well as more reporting and public oversight. The rule will also likely create time and cost impacts to projects in several ways, including: i) delays while permits are being obtained; ii) increased costs for monitoring equipment and enhanced erosion and sediment control and pollution prevention measures; and, iii) increased man-hours due to daily monitoring requirements. Much of the risk will fall to the project delivery team member responsible for obtaining the permit and ensuring compliance – particularly compliance with the new numeric limits. The current rule does not assign risk to any one entity. Prudent construction professionals should recognize these costs and consider how the risks associated with such monitoring should be allocated among the contracting parties, or how, through proper sequencing of work, they might be avoided.

G. Fritz Hain
Member of the State Bar of Georgia

G. Scott Walters
Member of the State Bar of Georgia and the District of Columbia

G. Fritz Hain and G. Scott Walters

Smith, Currie, & Hancock LLP