ICYMI: Navigating NPDES Wastewater Permitting: Best Practices, Watch Outs and Lookaheads

If you missed our webinar on Navigating National Pollutant Discharge Elimination System (NPDES) Permitting last week or need a written summary to refer back to, read along for a summary of best practices, watchouts, and lookaheads to consider in your next NPDES renewal or modification! This is an update to our original blog on the subject from 2020.

What is NPDES?

NPDES is a national program with the purpose of reducing pollutants in discharges to water of the U.S. (WOTUS), enforced through the Clean Water Act (CWA). If your facility discharges wastewater from an outfall to WOTUS, you very likely have an NPDES discharge permit (or need one), which must be renewed every five years.

Best Practices

When should I start working on my NPDES renewal application?

Generally speaking, the sooner the better! Renewal applications must be submitted at least six months prior to the expiration date of the permit (some states require even earlier – including Rhode Island). Depending on the complexity of the permit, whether changes are being requested, and the required sampling, ALL4 recommends getting started with a renewal application six months to a year prior to the due date.

What changes can I request in my NPDES renewal application?

With sufficient technical and/or regulatory justification, changes to permit limits, units (concentration vs. mass-based), monitoring frequencies, and pollutants monitored can all be requested in an NPDES renewal application. Think about changes you would like to make, which permit limits or conditions cause extra burden, and consider how you might justify a change. Resources like U.S. EPA’s 1996 Interim Guidance for Performance-Based Reductions of NDPES Permit Monitoring Frequencies (an oldie but a goodie) and the NPDES Permit Writer’s Manual are helpful in evaluating these requests.

Watch Outs

Sampling and Analysis

NPDES renewal applications normally require effluent sampling and analysis beyond the routine requirements of the permit. Be sure you understand state- or industry-specific requirements for the parameters to analyze, the number of sampling events, and the conditions of sampling events (this is a great topic to discuss during a pre-application meeting). Examples of some state-specific sampling nuances we’ve come across:

• Pennsylvania requires three rounds of sampling events.
• North Carolina requires facilities to submit documentation of any pollutant with a certified test method at 40 CFR 136 if their discharge is anticipated.
• Georgia and Mississippi require additional toxicity testing during renewal years.
• Some states (e.g., Kansas) require minimal sampling with the renewal application but may request additional data following submittal.

Technology Based Effluent Limits

If your facility is subject to one or more effluent limit guidelines (ELGs) at 40 CFR 405-471 and has Technology Based Effluent Limits (TBELs), production data provided in your renewal application will be used to re-assess TBELs for the upcoming permit term. Check your specific ELG(s) for any nuances but generally production values used for TBELs should reflect actual production during the previous permit term and anticipated changes in the upcoming permit term (for example, if your facility was slowed back during your previous permit term but anticipates ramping back up in the upcoming permit term or has a planned expansion project in the upcoming permit term). States may refuse to increase TBELs based on an increase in production unless certain criteria are met due to anti-backsliding.

Cooling Water Intake Structures and Best Professional Judgement

Cooling Water Intake Structures (CWIS) are defined as intake structures withdrawing at least two million gallons per day (MGD) of flow, 25% of which is used exclusively for cooling purposes. Facilities with cooling water intake structures are required to provide additional information in the NPDES renewal process and must implement one of seven options to reduce mortality to fish and other aquatic organisms. Many facilities have intake structures that do not meet the definition of a cooling water intake structure; however, ALL4 has seen an uptick in scrutiny of these seemingly exempt CWIS during the NPDES renewal process. The increased scrutiny is substantiated by U.S. EPA’s wide latitude afforded in 40 CFR 125.90(b), which states that CWIS not meeting the applicability thresholds of the rule “must meet requirements under section 316(b) of the CWA established by the Director on a case-by-case, best professional judgment (BPJ) basis.”

Lookahead

Here are a few updates on the horizon that may impact your next NPDES renewal:

• As of Fall 2024, U.S. EPA planned to revise its Form 2C for NPDES applications to include Per- and polyfluoroalkyl substances (PFAS) sampling requirements. The pollutants list on Form 2C was last updated in 1987. This change is currently targeted for final rulemaking by the end of 2026.
• Some states are moving toward E. coli and/or enterococci rather than fecal coliform monitoring. States are also scrutinizing fecal indicator bacteria detected in effluent even for facilities that do not treat domestic waste, so be sure you are confident in the data you submit in your application!
• As part of the Preliminary Effluent Guidelines Program Plan 16, U.S. EPA has determined that detailed studies of the Battery Manufacturing Category, the Centralized Waste Treatment Category, the Oil and Gas Extraction Category, and PFAS processors (industrial facilities engaged in processing raw PFAS into commercial products) are warranted.
• We would be remiss to not acknowledge the current changes going on in the federal government that are likely to impact U.S. EPA and its funding in the near future. We may start to see states step up and take stronger leads with BPJ limits – for more on that subject, check out our blog Water Quality Compliance in the Trump Era.

If you have questions regarding NPDES permitting, please contact Lizzie Smith at lsmith@all4inc.com or at (770)-999-0269.