The U.S. Environmental Protection Agency proposed on May 18 changes to the Steam Electric Power Generating Effluent Limitations Guidelines (ELGs) under 40 CFR Part 423, mainly regarding wastewater generated from coal combustion residual (CCR) management units such as ash landfills and surface impoundments by extending compliance dates and allowing consideration of characteristics of the site and power plant operations and costs to determine leachate management steps.
The EPA states the proposal is intended to support electric grid reliability and reduce compliance costs while continuing to protect water resources.
The preamble cites the Supreme Court decision of County of Maui v. Hawaii Wildlife Fund, 590 U.S. 165 (2020), stating: “Discharges that flow through groundwater before reaching surface waters that are the ‘functional equivalent’ of a direct discharge from a point source to a WOTUS are considered direct discharges and must comply with effluent limitations in NPDES permits” and applicable standards can be set based on best professional judgment.
Key proposed changes include:
- Revision of ELG requirements for “unmanaged combustion residual leachate” of CCR landfills and legacy impoundments not previously subject to the most stringent discharge controls
- Utilizing other options rather than the strict “zero-discharge” technology standard of the 2024 rule
- Extension of compliance deadlines for several wastewater categories, including CCR leachate
- Allowing for permitting authority discretion on site-specific technology application, implementation schedules, and alternative compliance dates.
CCR leachate can contain arsenic, selenium, mercury, boron, cadmium, chromium, lithium, molybdenum, and other dissolved constituents capable of migrating into groundwater from unlined or leaking disposal units.
The EPA estimates that the proposal could reduce annual electricity generation compliance costs by up to approximately $1.1 billion compared with implementation of the 2024 requirements.
Comments are due June 17. Click here to read the proposal.