Indiana has not updated its Industrial Stormwater Discharge General Permit “Rule 6” regulations since 2003. This presentation summarizes what IDEM (Indiana Department of Environmental Management) has been doing in the past couple of years to update its program. At a national and state level, additions have been made in the last 20 years to the regulatory framework for manufacturers and other parts of the supply chain regarding stormwater monitoring and quality standards. In 2021, the EPA issued its Multi-Sector General Permit (MSGP) and many states have used that as a guide to update their general permits.

Likewise, Indiana is in the process of updating its stormwater permitting requirements. In July 2022, a draft permit was sent to EPA. Between October 2022 and March 2023, IDEM collaborated with a workgroup of interested parties to further refine the draft permit. A revised draft permit will be provided to EPA again prior to putting the draft permit out for public comment. The public comment phase will occur in 2024, followed by issuance of the final permit. Potential changes in the current Indiana general permit include monitoring for additional pollutants and more frequent monitoring. The additional pollutants will be specific to the permittee’s business sector (i.e. SIC code). Regardless of the sector, the permittee will need to compare their monitoring results to numerical benchmarks. If the benchmarks are exceeded, the permittee will be required to implement corrective measures with the goal of lowering the concentrations in the runoff and achieving the benchmark levels. Success in the quality improvements will be based on quarterly sampling that must continue until the benchmark goals are achieved. Permittees will also need to know more about the stream that receives their stormwater. Is the stream an “impaired water”? Is there a TMDL (Total Maximum Daily Load)? These designations are made by IDEM and are longstanding programs in the agency’s management of waters of the state. However, the new General Permit will be the first widespread application of these programs to stormwater runoff from industrial sites. KERAMIDA’s forecast? The IDEM Stormwater General Permit for Industrial Activities will be on the Bestsellers Reading list for Environmental Managers in 2024.

KERAMIDA’s recommendations? Before the permit is issued, identify your 1) sector, 2) benchmarks, and 3) receiving water status. Then determine how you may be impacted by the new permit requirements.

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