The South Carolina Department of Health & Environmental Control has issued as final the Industrial Stormwater General Permit (SCR000000) on September 1, 2016, and became effective on October 1, 2016. Some of the key changes compared to the South Carolina Permit issued in 2010 are:
- Saltwater/Freshwater benchmark metal concentrations are set for all facilities covered by the permit as applicable. The 2010 permit had only Freshwater values.
- The permit added bacteriological parameter monitoring based on a site’s receiving waterbody classification. This is in the form of a benchmark for domestic wastewater treatment plants, meat packing (animal killing) plants, wool scouring (textile) plants, and rawhide (leather) plants only. The previous permit had only the old (pre-2013 change) Freshwater bacteriological standard for these types of industrial activity covering the entire stateand did not take into account any given site’s receiving water classification.
- A numeric effluent limit has been added for Sector S. The limit is for ammonia analyzed as nitrogen and pertains to de-icing compounds used at airports with a 1000 or more annual departures. The New Source Performance Standard (NSPS) that has this limit was promulgated mid-term of the IGP in 2012. The permit incorporated this requirement.
- The inclusion of the unauthorized non-stormwater discharges evaluation into the comprehensive inspection requirements. The previous permit gave no frequency for the evaluation; including the evaluation in the comprehensive inspection eliminated that ambiguity.
- While the permit continues the exemption from monitoring for discharges that are determined to be natural background or would not contribute the pollutant of concern to an impaired receiving waterbody, it will also extend those exemptions to the TMDL level as well.
- The permit also has an additional “out” from monitoring for discharges into a TMDL watershed. If the water quality monitoring station immediately downstream of a site (and upstream if in tidally-influenced waters) is fully supporting the water quality standard for the impaired parameter(s), then the site is exempt from the TMDL monitoring.
- The permit continues to require that each permittee check the South Carolina list of approved TMDL during each comprehensive site inspection. The permit now adds a check of the 303(d) list as well. The 303(d) list is reviewed and updated biennially by the Department. Inclusion of a check of the 303(d) list in the comprehensive inspection along with the TMDL check offers a streamlined, complete review of a site’s water quality status.
- TSS benchmarks have been added for Sectors F and N. These requirements were removed in the 2010 version of the IGP and are added back due to the MSGP continuing to have them in the Sectors.