40 CFR §125.67

1. (a)No modified discharge may result in any new or substantially increased discharges of the pollutant to which the modification applies above the discharge specified in the section 301(h) modified permit.
2. (b)Where pollutant discharges are attributable in part to combined sewer overflows, the applicant shall minimize existing overflows and prevent increases in the amount of pollutants discharged.
3. (c)The applicant shall provide projections of effluent volume and mass loadings for any pollutants to which the modification applies in 5-year increments for the design life of its facility.