Thursday, January 8, 2009

Stormwater Effluent Limits For Industrial - MS4; Are These Next?

US EPA has recently proposed effluent limits for stormwater discharges from larger construction sites. [Read more about Construction Stormwater Discharge Limits]. This has prompted many industrial and municipal stormwater permitees to speculate on whether or not similar effluent limits will be proposed under Multi-sector General Permits (MSGP) or MS4 permits.

The simple answer is that almost anything is possible.

However, the establishment of construction site effluent limits has some important differences that may not allow easy transfer of the same effluent limits to industrial or MS4 permits.

  1. Effluent limits are based on a specific stormwater treatment method that is added to the stormwater treatment pond requirements for smaller sites. Without the requirement to install a pond, the additional treatment may not be economically-feasible. Unless specific structural BMPs, like ponds, are required for industrial or MS4 dischargers, it would be difficult to translate the construction site effluent limits. Because of the nature of industrial and MS4 discharges, requiring treatment ponds would be difficult.

  2. In general, the variety of activities and stormwater handling practices associated with industrial and MS4 discharges will be significantly broader compared to construction sites. Therefore, again, translating the proposed effluent limits to industrial and MS4 dischargers would be difficult.

Given these factors, it may be difficult to demonstrate that similar Best Available Technology used to calculate effluent limits for construction site discharges could be equally applied to other types of discharges.

Caltha LLP provides expert technical support in permitting and compliance with State and Federal stormwater permits. To request a quote of services on-line, go to Caltha Stormwater Quote Page.

For further information contact Caltha LLP at
Caltha LLP Website

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