Overall, IDEM will issue permit coverage under a general permit to most, if not all, of the designated MS4 entities in Indiana. The Phase II designated MS4s will be issued coverage under the MS4GP. The MS4GP is a general permit that is written to cover multiple permittees. All permittees are required to comply with the requirements in the MS4GP. Notices of Intent (NOI) for a general permit can be submitted by either a single MS4 entity, or multiple MS4 entities that choose to operate as co-permittees.
To be eligible to obtain permit coverage under a general permit, a permittee cannot already be covered under an individual MS4 permit. The individual MS4 permit will always take precedence over a general permit, and may include requirements that are different from those found in the MS4GP.
Under 327 IAC 15-2-9(b), an individual NPDES permit is required when water quality standards are not being met under the general permit, technology or regulatory change has occurred that causes the implementation of specific controls or limitations not expressed in the general permit, or a general permit is no longer appropriate based on permittee changes. If any of these situations occur, MS4 entities covered under the MS4GP may be required to terminate coverage and apply for an individual MS4 permit.
An individual permit is a permit drafted by IDEM to cover only one permittee, or several co-permittees. This type of permit is written and tailored to the specific permittee(s) and will contain conditions and requirements that are often different (usually more stringent or specific) from a general permit. Because this type of permit’s requirements are written, and tailored to the permittee(s), it takes much longer to create. This type of permit is utilized most often in situations where a general permit is not providing adequate requirements to protect Indiana’s water resources and requirements need to be tailored to provide additional protection. The two types of individual permits that may be considered are:
Statewide Individual Permit
IDEM will utilize statewide individual permits for specific situations, where the permittee is responsible for multiple facilities or areas throughout the entire state. The Indiana Department of Transportation is being considered for this type of permit.
MS4 Area Individual Permit
Individual permits provide coverage to a single MS4 area. This MS4 area can include either one entity or multiple regulated entities. For multiple entities, the minimum measure responsibilities for each entity must be indicated, and agreed upon by the entities, in the application for permit coverage.
Under Phase I federal stormwater regulations, regulated MS4 entities were required to obtain individual permits. Initially, only the City of Indianapolis obtained an individual permit. Another option for Indiana Phase II-regulated MS4 entities located near a Phase I permittee is to seek coverage under an existing Phase I individual permit when the individual permit is up for its five-year renewal.
Individual MS4 permits are required for MS4 entities that, according to 40 CFR 122.26, are still classified as large and medium MS4s, after an allowance for percentage of combined sewer system is calculated. IDEM is in the process of evaluating other Phase II MS4s that will be required to obtain permit coverage under an Individual permit.