Contractors will have greater flexibility in controlling stormwater discharges from construction sites under the U.S. Environmental Protection Agency's new revisions to its effluent guidelines.

The final rule, to take effect on May 5, addresses concerns industry groups have had with the rule since it was implemented in 2009, especially its numeric discharge limit of 280 nephelometric turbidity units for construction sites in which 20 or more acres are disturbed at one time.

A 2012 settlement in a lawsuit brought by the National Association of Home Builders (NAHB) and other groups challenging the data used to develop the turbidity limitations led EPA to suspend the requirement and take steps to amend the rule permanently.

"The numeric criterion would have applied everywhere in the country, so that a project in an extremely wet area would be treated the same as one in an extremely dry area," says Nick Goldstein, American Road & Transportation Builders Association vice president of environmental and regulatory affairs. "That just didn't make sense."

The revised rule, published in the March 6 Federal Register, withdraws the limit completely. It also clarifies the applicability of best management requirements for stabilizing soil, preserving topsoil and preventing pollution in the construction phase only. The rule allows exceptions where specific practices are deemed infeasible.

EPA said in a statement that no numeric limit is under development at this time "because there is insufficient data on which to base that limit."

Ty Asfaw, NAHB senior program manager, says the numeric limit would have limited contractors' compliance options to centralized stormwater-management approaches, such as detention basins and chemical additives, which could hike construction costs by as much as $6,000 per home.

Asfaw adds, "The rules allow for more decentralized approaches, which is more in keeping with the industry-wide paradigm shift toward green infrastructure."