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Stormwater Manual Update Project
The Department is currently working on a substantial revision of Chapter 500 which is expected to result in new stormwater management standards. The Manual will need to be updated to provide the essential technical guidance for the proper understanding and implementation of the new standards by the stakeholders and regulated community. More information on the Department’s engagement with Chapter 500 stakeholders is available.
Contractor
The Department has a contract with Comprehensive Environmental Inc. (CEI) for the manual update. The University of New Hampshire Stormwater Center is also participating in the project as a subcontractor.
Workgroup
The Department has formed a Workgroup consisting of the Department staff and external subject matter experts to guide the project efforts and provide input.
Workgroup meetings
May 19, 2025 - Project Introduction:
Presentation | Minutes
Primary Objectives & Expectations
The project consists of updating the Manual in conjunction with the Department’s ongoing Chapter 500 rulemaking effort. Major objectives of the project include:
- Update the content of the SW Manual in accordance with Best Available Information (BAI) to provide effective guidance for regulatory compliance,
- Improve the format of the SW Manual for better end user experience.
Tasks & Schedule
The project started in March 2025 and is anticipated to end in October 2026.
| Tasks | Anticipated Dates |
|---|---|
|
Scope of Work Finalization: |
March-July 2025 |
| Draft Revisions to the Manual | August 2025–March 2026 |
| Public Informational Webinar on the Draft Revisions | April 2026 |
| Public Comment Process | April-May 2026 |
| Final Revisions to the Manual | July–October 2026 |
| Manual Workshop | October 2026 |
Opportunities for Feedback
As of May 2025, needs assessment is underway to identify the topic areas for which the manual needs improved or new content. The topic areas preliminarily identified by the Department are presented below.
The manual users are encouraged to send their comments and suggestions on the manual content to Kerem Gungor.
Topic Areas Needing New or Updated Content (Preliminary)
- Stormwater Regulatory Framework
- Climate Change: Adaptation & Resilience
- LID
- Nature-based solutions: Vegetation, Soil Decompaction and Amendment
- Infiltration
- Rainwater Harvesting
- Proprietary BMPs
- Retrofit BMPs
- BMP Selection
- BMP Operation and Maintenance
- Chapter 500 Compliance
- Source Control BMPs
- BMP Design & Implementation: Criteria & Specifications Continuous Monitoring and Adaptive Control/Smart BMPs
- BMPs for Emerging Contaminants
- Stormwater Monitoring