Section 434.72 - Effluent limitations attainable by the application of the best practicable control technology currently available (BPT)(a) The operator must submit a site-specific Pollution Abatement Plan to the permitting authority for the pollution abatement area. The plan must be approved by the permitting authority and incorporated into the permit as an effluent limitation. The Pollution Abatement Plan must identify characteristics of the pollution abatement area and the pre-existing discharges. The Pollution Abatement Plan must be designed to reduce the pollution load from pre-existing discharges and must identify the selected best management practices (BMPs) to be used. The plan must describe the design specifications, construction specifications, maintenance schedules, criteria for monitoring and inspection, and expected performance of the BMPs. The BMPs must be implemented as specified in the plan.(b)(1) Except as provided in 40 CFR 125.30 through 125.32 and paragraph (b)(2) of this section, the following effluent limits apply to pre-existing discharges: Effluent Limitations
| Pollutant | Requirement |
| (i) Iron, total | May not exceed baseline loadings (as defined by appendix B of this part). |
| (ii) Manganese, total | May not exceed baseline loadings (as defined by appendix B of this part). |
| (iii) Acidity, net | May not exceed baseline loadings (as defined by appendix B of this part). |
| (iv) TSS | During remining and reclamation, may not exceed baseline loadings (as defined by appendix B of this part).
Prior to bond release, the pre-existing discharge must meet the applicable standards for TSS or SS contained in subpart E.1 |
1 A pre-existing discharge is exempt from meeting standards in subpart E of this part for TSS and SS when the permitting authority determines that subpart E standards are infeasible or impractical based on the site-specific conditions of soil, climate, topography, steep slopes, or other baseline conditions provided that the operator demonstrates that significant reductions of TSS and SS will be achieved through the incorporation of sediment control BMPs into the Pollution Abatement Plan as required by paragraph (a) of this section.
(2) If the permitting authority determines that it is infeasible to collect samples for establishing the baseline pollutant levels pursuant to paragraph (b)(1) of this section, and that remining will result in significant improvement that would not otherwise occur, then the numeric effluent limitations in paragraph (b)(1) of this section do not apply. Pre-existing discharges for which it is infeasible to collect samples for determination of baseline pollutant levels include, but are not limited to, discharges that exist as a diffuse groundwater flow that cannot be assessed via sample collection; a base flow to a receiving stream that cannot be monitored separate from the receiving stream; a discharge on a steep or hazardous slope that is inaccessible for sample collection; or, a number of pre-existing discharges so extensive that monitoring of individual discharges is infeasible.