Chapter 12: Stormwater Management Plan

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A Stormwater Management Plan documents how the proposed stormwater management measures meet the stormwater management standards, performance criteria, and design guidelines contained in this Manual, as well as other local, state, and federal stormwater management requirements.

A Stormwater Management Plan is required as described in Chapter 4 - Stormwater Management Standards and Performance Criteria, a Stormwater Management Plan is required (Standard 5 – Stormwater Management Plan) for all new development, redevelopment, retrofits, and other land disturbance activities that require a local, state, or federal permit or approval. A Stormwater Management Plan is not required for retrofit

projects that do not require review and approval, although designers are encouraged to document the design basis for all stormwater retrofits following good engineering/design practice. A Stormwater Management Plan should be prepared by the project proponent and designing qualified professional, as defined in the General Permit for the Discharge of Stormwater and Dewatering Wastewaters from Construction Activities and submitted for review by the local or state reviewing authority.

The chapter presents the recommended minimum content for a Stormwater Management Plan. Many municipalities and state agencies have stormwater management submission requirements as specified by municipal land use regulations and state permit programs. The recommended Stormwater Management Plan presented in this chapter is provided as guidance only and does not replace other local and state submission requirements. Municipalities or state agencies may adopt this or similar Stormwater Management Plan requirements into future updates of municipal land use regulations and state permit programs.

Plan Content

Layout of what is needed within the plan.

Stormwater Management Report

Layout of what should be addressed within the stormwater management report (written narrative of project including existing and proposed conditions, stormwater management measures, and inclusion of Manual standards and performance criteria).

Summary of Compliance with Stormwater Management Standards and Criteria

What is needed to demonstrate compliance with the following standards:

  • Standard 1: Runoff Volume and Pollutant Reduction (for each design point for Site Development and Redevelopment Projects)
  • Standard 2: Stormwater Runoff Quantity Control for Site Development and Redevelopment Projects (for each design point)

Design Calculations

Necessary design calculations to demonstrate compliance with the above standards (1 and 2) and performance criteria explained in Chapter 4.

Design Drawings

Design drawings for the following areas, prepared by a designing qualified profession, should be signed, sealed, and included with the plan:

  • Existing (pre-development) conditions plan
  • Proposed (post-development) conditions plan
  • LID site planning and design opportunities and constraints plan
  • Structural stormwater BMP design details and notes

Soil Erosion and Sediment Control Plan

Project proponents must develop and implement a Soil Erosion and Sediment Control Plan in accordance with the Connecticut Guidelines for Soil Erosion and Sediment Control.

Operation and Maintenance Plan

Layout of recommended inclusions for the long-term Operation and Maintenance plan required by standard 4 (identified required inspection and maintenance activities for structural stormwater BMPS).

Other Supporting Documents 

List of other information relevant to stormwater management measures which should be included in the Plan.