Connecticut’s Department of Energy & Environmental Protection (DEEP) recently revised their general permitting system for industrial wastewater discharges. Before October 2025, dischargers of process wastewater that were not considered Significant Industrial Users (SIU), or did not fall under the jurisdiction of an Individual Permit due to more complex wastewater discharges, were required to obtain a General Permit for Discharges from Miscellaneous Industrial Users (MIU GP). The permit was overseen by a municipality’s Publicly Owned Treatment Works (POTW), and the POTW’s discharge prohibitions could be more stringent than state effluent limits. Laboratory wastewater was considered “other process wastewater” that warranted notification if maximum daily flow was greater than 1,000 gallons per day, unless the discharger was likely to exceed effluent limits, such as having process wastewater outside of the acceptable pH range.
Effective October 29, 2025, DEEP replaced the MIU GP with the Non-SIU General Permit (Non-SIU GP), and MIU GP holders were required to submit notification forms to the CT DEEP and their POTW by March 1, 2026. New permittees must submit notification at least 60 days before they commence wastewater discharge. One of the major changes is the pH effluent limit; the previous acceptable pH range was 5.0 to 12.0, and the new allowable pH range is 5.5 to 10.0. MIU GP holders have until October 2027 to comply with the new pH limits.
It should be noted that laboratories that treat liquid biological waste with bleach before discharging might exceed the new pH range limit, and their wastewater might require pretreatment and monitoring prior to discharge.
Notification forms must include wastewater discharge screening analysis (sampling) by a certified laboratory, conducted within 90 days of submission. If discharge has not yet started, results must be submitted within 30 days of discharge initiation. Per- and polyfluoroalkyl substances (PFAS) screening must also be included if the discharger is in a particular industry category such as a chemical manufacturing. While there is no fee to submit a notification form to the DEEP, submission to local POTWs might include fees and additional requirements.
Non-SIU GP holders must comply with the following conditions:
- Discharges must remain within effluent limits for substances such as oil and grease, organic pollutants, and metals, as well as the allowable pH range.
- Flow must be measured, and total daily flow must be recorded. If the maximum daily flow is less than 5,000 gallons per day, flow estimates suffice.
- Wastewater that requires pH adjustment must be continuously monitored.
- Pretreatment systems and monitoring equipment must be maintained.
- An Operations and Maintenance (O&M) Plan and a Spill Prevention and Control Plan must be developed and made available in the event of an inspection.
Industrial wastewater dischargers that require a Non-SIU General Permit must ensure they submit the required notification form, coordinate sampling, and conduct appropriate monitoring to ensure discharge remains within the new CT DEEP effluent limits.
For assistance with wastewater compliance at your facility, or for more information about the Non-SIU General Permit, please contact us!
