NPDES Permit Modifications

An NPDES permit may only be modified during its term. The term of an NPDES permit is the time period between the permit's effective and expiration dates.  If a permittee makes a timely and complete reapplication for their NPDES permit and the permit is not reissued by the Bureau before the permit expires, the permit continues in effect until a final decision on the renewal application.  Since the term of a permit is not extended when a permit continues in effect past its expiration date, an expired permit that continues in effect can not be modified except by reissuance.  The reason for this is simply that the administrative process to reissue a permit and the administrative process to modify a permit are the same.  Therefore, there is no reason to modify a continued permit since the modifications can be addressed by reissuing the permit.

Also, a permit modification can only be made if a cause for modification exists.  Section 122.62 of SC Regulation 61-9 gives the causes for modification that must exist before a permit can be modified.  Please visit the NPDES WEB page on "Causes for Modification" to see the exact regulation requirements on causes for modification.

Modifications are divided into two broad categories.  The two categories are Minor Modifications and Major Modifications.  Minor modifications can be made with the consent of the permittee without following the normal administrative procedures for proposed permit decisions, such as public notice, etc.  Options for minor modifications are detailed in Section 122.63 of SC Regulation 61-9.

If a permittee does not consent to a modification that is listed as a minor modification, the Bureau may still modify the permit.  However, the permit modification is not a minor modification.  It is a major modification which must be processed by following the complete administrative process for permit decisions.

Any modification which is not listed as a minor modification is a major modification.  Therefore, major modifications are:

A proposed major modification must follow all the administrative procedures for permit decisions, such as public notice, public hearing, if required, etc.  The method of public notice is determined based on the EPA classification of the NPDES permit and/or the type of modification.  Any major modification of an NPDES permit that is classified as a Major NPDES permit using EPA's rating system must be published in a newspaper of general circulation of the area of the discharge.  The method of public notice for a major modification of an NPDES permit that is classified as a Minor NPDES permit using EPA's rating system varies depending on the type of modification.  A proposed modification of a minor NPDES permit which proposes an increase in the discharge volume or loading of any pollutant or relaxes a permit limit is public noticed in a newspaper.  Other major modifications of minor NPDES permits are public noticed by posting the notice in three public places.  For more information on public notices, please visit our NPDES WEB page on Public Notice Requirements.

Major modifications may be appealed.  If a modification is appealed, the proposed modifications of the permit are stayed pending the outcome of the appeal process.  The other portions of the permit that are not affected by the proposed permit modification remain in effect.

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