The EPA published a final rule on March 6th that clarifies the requirements for the construction industry to use best management practices (BMPs) to control stormwater and minimize soil erosion and pollutant discharges. The EPA decided to apply BMPs rather than set numeric turbidity effluent limits, but the agency reserved the right to revisit discharge limits in the future.

The rule applies to construction activities such as clearing, excavating and grading that disturbs the soil. If not managed properly, these activities can result in discharges off the construction site that cause physical, chemical and biological impacts on receiving waters.

The final rule requires the use of erosion control practices to reduce the volume and velocity of stormwater flows from construction sites, this includes both peak flow rates and total storm volume. The BMPs include providing and maintaining buffers, keeping the length of slopes short, using low gradients, preserving top soil, and preserving natural vegetative cover.

The rule includes a definition of “infeasible” in an effort to clarify that there may be times when protective actions are not technologically possible, or not economically practicable and achievable in light of best industry practices.

Stabilization of disturbed areas must, at a minimum, be initiated immediately whenever any clearing, grading, excavating or other earth disturbing activities have permanently ceased on any portion of a construction site, or temporarily ceased 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 vegetative stabilization measures immediately is infeasible, alternative stabilization measures must be employed. Stabilization must be completed within a period of time determined by the permitting authority. In limited circumstances, stabilization may not be required if the intended function of a specific area of the site necessitates that it remain disturbed.

It is also necessary to minimize the exposure of building materials, building products, construction wastes, trash, landscape materials, fertilizers, pesticides, herbicides, detergents, sanitary waste and other materials present on the construction site to precipitation and to stormwater, except where the exposure to precipitation and to stormwater will not result in a discharge of pollutants, or where exposure of a specific material or product poses little risk of stormwater contamination.

The EPA rule changes are the result of a December 2012 settlement between EPA and the Wisconsin Builders Association, the National Association of Home Builders, and the Utility Water Act Group to resolve a lawsuit over prior stormwater rules.

The text of the final EPA rule is available here. The rule will go into effect on May 5, 2014.