General Pretreatment Permit for Significant Industrial User, Dewatering, and Remediation Discharges (SIU GP)
The General Pretreatment Permit for Significant Industrial User, Dewatering, and Remediation Discharges (SIU General Permit) regulates discharges of industrial process and non-process wastewater from Significant Industrial Users (SIUs), as well as remediation, cleanup, and construction-related dewatering discharges to municipal Publicly Owned Treatment Works (POTW).
Established to ensure consistent regulatory oversight and effective environmental protection, the SIU GP applies to facilities and sites whose discharges may present an increased risk to municipal treatment systems due to flow volume, pollutant characteristics, or the nature of industrial or remedial activities.
The SIU GP supports the objectives of the State Pretreatment Program by protecting municipal wastewater infrastructure, safeguarding human health, and preserving water quality through standardized requirements and enhanced oversight.
Quick Links
- SIU General Permit
- Application Timeline Deadlines
- Application Process & How to Apply
- Permit Conditions
- Guidance for POTWs
- Additional Resources and Contacts
- Pretreatment Compliance Assistance Page
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Use the Pretreatment Permit Decision Chart to determine if this permit is right for you.
**The General Pretreatment Permit for Significant Industrial User, Dewatering, and Remediation Discharges was issued on October 29, 2025**
**Registration Opens December 1, 2025**
Tip: The permit includes Smart Navigation - integrated smart links for fast and seamless navigation. One-click access to key sections.
- General Pretreatment Permit for Significant Industrial User, Dewatering, and Remediation Discharges
Appendices - Appendix A - Operations and Maintenance Plan
- Appendix B - Spill Prevention and Control Plan
- Appendix C - Solvent Management Plan
- Appendix D - Monitoring Waiver
- Appendix E - POTWs Subject to Phosphorus Monitoring
- Appendix F - Connecticut POTWs Authorized to Accept Transported Non-Domestic Wastewater
- Appendix G - Sections of RSCA and Additional Parameters
- Appendix H - Categories of Wastewater Requiring PFAS Screening
- Appendix I - PFAS Analytes
- SIU General Permit Fact Sheet
- SIU General Permit Response to Comments
- SIU General Permit FAQs
Application Timeline & Deadlines
Application Deadlines for Existing Permittees
Existing Permittees: Sites covered under the previous permit (SIU GP issued 2020) are required to apply by March 1, 2026
Note: Interim permit coverage is provided as long as a complete and timely application is received
Application for New Site
New sites must apply 180 days (6 months) prior to initiating discharge
Application Process & How to Apply
Starting December 1, 2025, you can apply for the SIU GP.
Explore the step-by-step Application User Guides below:
- Application Guidance for Significant Industrial Users
- Application Guidance for Dewatering and Remediation Wastewater
How to Submit Your Application
The application process is a 5-step time-sensitive process
Step 1 - Prepare
Review the permit and confirm eligibility requirements.
Step 2 - Complete the Application Form
Refer to the Application User Guide for step-by-step instructions and the list of required information needed to complete the form.
Step 3 - Submit the Application Transmittal Form
The Application Transmittal Form allows DEEP to track fee payments and match them to the correct application. The Permit Application Transmittal Form is required for this general permit and must be submitted with your permit-specific forms. Click to download the Word Doc or PDF version.
- After completing the Application Transmittal Form and required attachments, email it to: DEEP.CentralPermits@ct.gov
- Important: Keep a copy of your records. You will receive a confirmation email with instructions for submitting payment and accessing the file transfer site. Once the Application Transmittal Form is submitted, the remainder of the process is time-sensitive.
Step 4 - Upload Required Documents
Within 10 business days of submitting the Application Transmittal Form, upload all required documents to DEEP's File Transfer Protocol (FTP) site - File Sharing Website - using the instructions provided in your confirmation email.
Critical Deadline: Applications will be closed and rejected if required documents are not received within 10 business days. Submit documents as soon as possible after submitting the Application Transmittal Form.
Step 5 - Application Review and Decision
DEEP will begin processing your application upon receipt of all required documents.
A high volume of applications is expected near submission deadline, which may result in processing delays. To help avoid delays, submit your application well in advance of posted deadlines.
Application Form and Attachments for Industrial SIUs:
Application Form for Industrial SIUs
Application Attachments must be completed and submitted:
- Attachment B - Written Notification of Connection or Transport to POTW
- Attachment D - Discharge Information
- Attachment D1 - Metal Finishing Screening Tables
- Attachment D2 - Process and Non-Process Screening Tables
- Attachment F - Monitoring Waiver Form
- Attachment G - O&M Plan and SPC Plan Checklist
- Attachment H - Solvent Management Plan Checklist
- Attachment I - Electronic Subscriber Agreement for NetDMR
- Attachment J - Analytical Data Summary
- Attachment K - Request for Variance
Application Form and Attachments for Dewatering and Remediation Wastewater:
Application Form for Dewatering and Remediation Wastewater
Application Attachments must be completed and submitted:
- Attachment B - Written Notification of Connection or Transport to POTW
- Attachment D - Discharge Information
- Attachment D3 - Dewatering and Remediation Screening Tables
- Attachment I - Electronic Subscriber Agreement for NetDMR
Need Assistance with the Online Application
The Pretreatment Program Team can assist with questions related to the information required by the permit. The team does not provide IT support and cannot assist with account, login, or system-related issues.
For questions related to the permit:
DEEP Pretreatment Team - DEEP.Pretreatment@ct.gov
For technical issues with the online application system:
DEEP IT Support Team - DEEP.helpdesk.footprints@ct.gov
Due to anticipated high volume of inquiries, responses may take up 2-3 business days. Your patience is appreciated.
Common Omissions that Result in Processing Delays or Rejection
Application Resources
- NetDMR/CDX: EPA NetDMR Portal and DEEP NetDMR
- Central Data Exchange: CDX Sign-in
- NPDES eReporting Tool: eRule NetDMR Homepage
What to Expect From DEEP
- Incomplete applications will result in processing delays or rejections.
- DEEP expects a high volume of permits in the first 2 years of the permit term that may lead to delays in processing time.
- You will receive a "Notice of Coverage" from DEEP confirming permit coverage.
Do you Need to Make a Change at the Site? Notice of Change: When to Submit and When Fees Apply
When to submit a Notice of Change
|
Reason for Submittal |
Description / Trigger |
|
Name Change |
Permittee name has changed after the initial notification of discharge. This does not include transfers in ownership. This permit is not transferable. |
|
Correction of Information |
Application contains inaccurate or misleading information that must be corrected. |
|
Significant Facility Modifications |
Any change affecting the nature, volume, or characteristics of the discharge. |
|
Variance Request |
Permittee requests a variance from an effluent limitation or other condition of the permit. |
|
New Discharge |
Submitting screening results for a new discharge when screening results were not provided in the original application. |
|
Change in Activity or Pollutant Loading |
Change in the process generating the discharge or in the pollutant concentration of an existing pollutant. |
|
New Source of Water |
Introduction of a new water source into the process. |
|
New Pollutant |
Introduction of a pollutant not previously reported in the initial Application. |
|
Change in Flow |
Increase or decrease in the maximum daily discharge flow. |
|
Relocation of Monitoring Point |
Moving an existing sampling or monitoring location. |
|
Treatment System Modification |
Expansion, replacement, or alteration of the wastewater treatment system. |
Notice of Change Submission Requirements
|
Required Content |
Description |
|
Narrative Summary |
Description of proposed modification(s) and how they affect authorized discharge(s). |
|
Supporting Documentation |
Analytical data, process flow diagrams, or treatment system schematics. |
|
Implementation Timeline |
Expected start and completion dates of proposed changes. |
Notice of Change Requiring Fee
|
Description of Change |
Notes |
|
Adding a Discharge Serial Number (DSN) |
Attach updated discharge description |
|
Modifying the wastewater description |
Applies to process or chemical changes |
|
Introducing a new pollutant not identified in the approved registration |
Must include analytical data |
|
Changing pollutant loading beyond permitted conditions |
Requires POTW review |
|
Increasing the maximum daily flow |
Applies to any discharge |
|
Decreasing the maximum daily flow if monitoring frequency changes |
Provide rationale and calculations |
|
Changing the monitoring location |
Identify new location and justification |
|
Name Change |
Identify new permittee name |
|
Variance Request |
Must include variance request form signed by POTW |
|
New Discharge |
Must include analytical data |
|
Correction of Information |
Identify previously submitted info and corrections |
Where to Submit
|
Notice of Change Type |
Where to Submit |
|
Fee Required |
Submit Application Transmittal Form and Payment to DEEP’s Central Permit Processing Unit (instructions will be provided for uploading Notice of Change Form to online platform). |
|
No Fee Required |
Submit Notice of Change Form to DEEP.Pretreatment@ct.gov |
Permit Conditions for Industrial Users
The following conditions apply to industrial users authorized under the General Pretreatment Permit for Significant Industrial User, Dewatering, and Remediation Discharges (SIU GP).
pH Limit Compliance Schedule
- Existing permittees (covered under the 2020 General Permit) have two years from the effective date of this General Permit to achieve compliance with the required pH limits of 5.5-10.0 standard units.
PFAS Identification and Minimization Plan
- Industries with a known or potential presence of per- and polyfluoroalkyl substances (PFAS) must develop and implement a PFAS a Source Identification and Reduction Plan.
Discharge Sampling Requirements
- Sampling must be conducted at least annually for all authorized discharges in accordance with applicable monitoring requirements
Conditions and Best Management Practices (BMPs)
- The General Permit establishes specific conditions and BMPs applicable to each type of discharge to ensure protection of the POTW and the environment.
Guidance for POTWs
SIU General Permit Implementation Guide for POTWs
The Pretreatment Program reissued the SIU GP with major updates that will provide key benefits to POTWs:
- Enhanced infrastructure protection and operational control
- Comprehensive pollutant monitoring and source identification
- Improved administrative oversight and data collection
- Streamlined digital application submissions
In order to assists POTWs with these updates, the Pretreatment Program has developed guidance documents which outline the following topics:
- Key responsibilities in implementation
- An action plan to ensure compliance and readiness
- Compliance assistance tools
- Additional resources
Guide for POTWs: The 2025 SIU General Permit
Additional Resources and Contact Information
Pretreatment Program
Pretreatment Program Compliance Assistance
Industrial Wastewater
Contact Us:
Have a question? Need help with your permit? We're here to help.
Pretreatment Program Staff:
Connecticut Department of Energy & Environmental Protection (DEEP)
Email: DEEP.Pretreatment@ct.gov
Content Last Updated: December 15, 2025