South Carolina DHEC Reissues the Industrial Storm Water General Permit

The South Carolina Department of Health and Environmental Control (DHEC) recently reissued its NPDES General Permit for Storm Water Discharges Associated with Industrial Activities (IGP). The IGP regulates discharge of storm water from industrial facilities to waters of the State and the United States through effluent limitations, monitoring and inspections requirements.  The 2016 IGP includes new requirements for certain industrial sectors while expanding and clarifying exemptions for others.  Many of the requirements apply statewide, but others apply only to specific industry sectors.  The IGP was effective on October 1 and replaces the 2010 IGP which expired in January, 2016. 

Major changes in the 2016 IGP include the addition of saltwater-specific benchmark monitoring concentrations for metals in discharges to saline waters.  Previously, freshwater metals concentrations applied statewide.  The 2016 IGP also includes benchmark monitoring requirements for bacteriological parameters (e.g., E. coli, fecal coliform) in storm water from domestic wastewater treatment plants, meat packing plants, wool scouring plants, and rawhide (leather) plants.  These benchmarks vary depending upon the use classification, e.g., freshwater, shellfish harvesting, of the receiving water body at a given site.  In contrast, the 2010 IGP applied a statewide freshwater bacteriological standard to these industrial sectors.

In addition to changes affecting discharges to saltwater, the 2016 IGP also includes new provisions related to storm water discharges to impaired water bodies.  Previously, the IGP included a monitoring exemption for pollutants determined to be attributable to natural background sources in discharges to impaired water bodies that were not yet subject to a Total Maximum Daily Load (TMDL).  The 2016 IGP extends this monitoring exemption to waters where a TMDL for the pollutant is being implemented.   For discharges to a TMDL water body, the 2016 IGP also provides an exemption from certain monitoring requirements if the water quality monitoring station immediately downstream of the site meets the water quality standard for the pollutant subject to the TMDL.  Finally, in addition to the 2010 IGP’s requirement for permittees to review DHEC’s list of established TMDLs during each annual comprehensive site inspection, the 2016 IGP requires permittees to review DHEC’s 303(d) list of impaired water bodies, including those for which no TMDL is established.

For existing permittees, DHEC will not require submittal of a Notice of Intent in order to maintain coverage under the 2016 IGP.  However, permittees should carefully review the 2016 IGP for changes impacting storm water discharges from their facilities, with a particular focus on the water use classification and water quality classification of their receiving water body.  

NPDES General Permit for Storm Water Discharges Associated with Industrial Activities