EPA Includes Numeric Turbidity Limit in Construction Effluent Limitations Guidelines

In a final rule issued November 23, EPA included a numeric limit for the turbidity of runoff from construction sites. Turbidity measures the cloudiness of water due to sediment being carried in the water. The rule was issued in compliance with a Court of Appeals ruling requiring that the rule be issued by December. EPA did not, however, include much-discussed post-construction effluent limits in the rule, instead explicitly noting its recently announced new rule to address post-construction runoff.

EPA established a phased implementation of the turbidity limit. The rule requires compliance with the turbidity limit of 280 nephelometric turbidity units (NTUs) for sites affecting 20 acres or more within 18 months of the effective date of the rule, and for sites affecting 10 acres or more within 4 years of the effective date of the rule.

The construction industry had opposed the turbidity limit, arguing that it was illegal because it was an indirect measurement of an already-regulated conventional pollutant, total suspended solids. The industry’s opposition may result in litigation over the legality of the rule.

Because water pollution permits are issued by state agencies in Georgia and many other states, implementation of the new rule will vary depending on when a particular state writes the new limits into its permits. It is unclear how the new rule’s requirements will affect Georgia’s current numeric turbidity limit in its existing general permits for discharges from construction activities. For more information on the new rule or its applicability to particular companies or projects, call Steve O’Day or Phillip Hoover.

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