On June 16, 2015, the EPA published a notice of final permit issuance for the NPDES General Permit for Stormwater Discharges from Industrial Activities (commonly referred to as the Multi-Sector General Permit or “2015 MSGP”). Click here to see the Multi-Sector General Permit. Many permittees will understandably focus on any changes made to the specific requirements for their sector. However, permittees should also pay attention to a change in permit coverage that affect all sectors; specifically, the list of allowable non-stormwater discharges found in section of the 2015 MSGP.

The MSGP is designed to only cover certain stormwater discharges; however, the permit includes a limited number of non-stormwater discharges that are also authorized. The previous version of the MSGP included the following on the list of allowable non-stormwater discharges.

  • pavement wash waters where no detergents are used and no spills or leaks of toxic or hazardous materials have occurred (unless all spilled material has been removed)
  • routine external building washdowns that do not use detergents

The 2015 MSGP narrows the scope of these authorized non-stormwater discharges (emphasis added):

  • pavement wash waters where no detergents or hazardous cleaning products are used (e.g., bleach, hydrofluoric acid, muriatic acid, sodium hydroxide, nonylphenols), and the wash waters do not come into contact with oil and grease deposits, sources of pollutants associated with industrial activities (see part 5.2.3), or any other toxic or hazardous materials, unless residues are first cleaned up using dry clean-up methods (e.g. applying absorbent materials and sweeping, using hydrophobic mops/rags) and you have implemented appropriate control measures to minimize discharges of mobilized solids and other pollutants (e.g., filtration, detention, settlement)
  • routine external building washdowns/power wash water that do not use detergents or hazardous cleaning products (e.g., those containing bleach, hydrofluoric acid, muriatic acid, sodium hydroxide, nonylphenols)

In explaining the rationale for adding these additional restrictions, the permit fact sheet simply notes that “cleaning agents other than detergents…could clearly have the potential to cause water quality issues if discharged.” The agency is also concerned with the mobilization of particulates and other pollutants during washing activities, and included examples of appropriate control measures to minimize this.

One commenter asked EPA to define “hazardous cleaning products.” EPA declined to do so, but pointed to the examples in the permit itself as well as the definitions of “hazardous materials/substances” and “uncontaminated discharge” in Appendix A of the 2015 MSGP. The term “Hazardous Materials or Hazardous Substances or Toxic Materials” is defined in part as “any liquid, solid, or contained gas that contain properties that are dangerous or potentially harmful to human health or the environment,”while the term “Uncontaminated Discharge” is defined as “a discharge that does not cause or contribute to an exceedance of applicable water quality standards.” Unfortunately, these definitions do not shed much light on what cleaning agents are now prohibited under the MSGP. EPA also warns that “packaging claims regarding environmental safety (of cleaning products) are not a sufficient determinant of product suitability.” Faced with this uncertainty, permittees will need to be very careful about what cleaning products to use, or risk a regulator determining that one of its discharges is not authorized under the MSGP.