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Effective June 1, 2009 - Revised Stormwater Manual (SWM)
The Revised Stormwater Manual table of contents is listed below with links to various sections of the document. Questions about content and requirements may be directed to Virginia Spillman in the Stormwater Management Division of Water Resources. Call her at 336-373-2055 or e-mail her.
Download the Entire Stormwater Manual - 4 MB (pdf)
SWM Cover Page (pdf)
Table of Contents (pdf)
1 Introduction (pdf)
1.1 Background
1.2.1 Non-Structural BMPs
1.2.1.1 Public Education
1.2.1.1.1 Employee Education of Commercial and Industrial Establishments
1.2.1.1.2 City of Greensboro Public Education Outreach
1.2.1.1.3 On-Site Refuse Management
1.2.1.1.4 Stormwater System Maintenance
1.2.1.1.5 Paved Area Sweeping
1.2.1.1.6 Used Oil Recycling
1.2.1.1.7 Material Exposure Controls to Avoid or Limit Exposure of Materials to Precipitation
1.2.1.1.8 Spill Prevention and Cleanup
1.2.1.1.9 Erosion and Sedimentation Control
1.2.1.2 Land Use Planning and Management
1.2.2 Structural BMPs
1.2.2.1 Open Vegetated Conveyance / Grass Swale
1.2.2.2 Riparian Buffers
1.2.2.3 Rooftop Runoff Management
1.2.2.4 Grass Paving
1.2.2.5 Natural Infiltration
2 North Carolina's Stormwater Requirements (pdf)
2.1 Overview of City of Greensboro’s Requirements
2.2.1 NPDES Discharge Permits
2.5 Water Supply Watershed Protection Requirements
2.9 City of Greensboro’s Requirements
2.9.1 City of Greensboro Stormwater Master Plans
2.9.2 Stormwater Management Plan
2.9.2.1 Stormwater Management / Watershed Development Plan Components
2.9.3 Stream Protection Requirements
2.9.3.1 Stream Channelization / Piping Restrictions
2.9.3.2 Stream Buffers
2.9.4 Modifications to Stormwater Requirements
2.9.4.1 Water Supply Watershed Protection
2.9.4.2 Stormwater Management Control
2.10 Regulatory Requirements
2.10.1 Jurisdictional Streams and Wetlands
2.10.2 FEMA Floodway / Floodplain
3 Stormwater Management Calculations (pdf)
3.1 Stormwater Management Objectives
3.1.1 Quality Control for High Density Development in Water Supply Watershed Areas
(Ordinance Section 30-7)
3.1.2 Quantity Control (Ordinance Section 27-22)
3.1.3 Engineer’s Certification of Stormwater Quantity Control
3.2 Peak Flow Calculations
3.2.1 Hydraulic / Hydrologic Methods
3.5.2 Drawdown Time Calculations for a Pond with an Orifice Outlet
3.6.3 Detention Storage Estimation Methodologies
3.7.1 Hydraulic Methodologies (Open and Closed Conveyance Analysis) 4 Selecting the Right BMP(pdf)
4.4 Comparison of BMP Treatment Capabilities 5 Common BMP Design Elements (pdf)
5.6 Earthen Impoundments, Embankments, and Dams
5.6.1 Seepage Control
5.7 Underdrain System
5.8 Outlets
5.8.6 Spillways
5.8.6.1 Chute Spillways
5.8.6.2 Free Overfall (Straight Drop) Spillways
5.8.8 Trash Rack 6 Landscape and Soil Composition Specifications (pdf)
6.4 Landscape Plans
6.5.1 Soils Analysis
6.5.3 Soil Specifications 7 BMP Inspection and Maintenance (pdf)
7.2 Legal and Financial Issues
7.2.2 Inspection and Maintenance Agreements
7.3.10 Dam Safety
7.3.11 Reduction of Pollutants Entering BMPs
7.3.12 Stabilization of BMP Drainage Area
7.3.13 Blockage of Outlets
7.3.14 Principal and Emergency Spillway 8 Level Spreader (pdf)
8.3.5 Stream Buffer Widths
8.3.6 Options where Level Spreaders Are Not Appropriate
8.3.12 Stabilization of BMP Drainage Area
8.5 Maintenance 9 Stormwater Wetlands (pdf)
9.3 Design
9.3.1 Understanding Basic Layout Concepts
9.3.2 Step 2: Determine the Volume to Treat
9.3.5 Outlet Design
9.4 Construction
9.5 Maintenance
9.5.1 Common Maintenance Issues
9.5.11 Reduction of Pollutants Entering Wetland
9.5.12 Stabilization of BMP Drainage Area
9.5.13 Blockage of Outlets
9.5.14 Principal and Emergency Spillway 10 Wet Detention Basin (pdf)
10.1 General Characteristics and Purpose
10.3.2 Siting Issues
10.3.3 Pretreatment and Inflow
10.3.4 Length, Width (Area), Depth, Geometry
10.3.6 Sediment Accumulation
10.3.7 Plant and Landscape Requirements
10.3.8 Surrounding Soils and Liners
10.3.10 Safety Considerations
10.4 Construction
10.5 Maintenance
10.5.1 Common Maintenance Issues
10.5.10 Dam Safety
10.5.11 Reduction of Pollutants Entering BMPs
10.5.12 Stabilization of BMP Drainage Area
10.5.13 Blockage of Outlets
10.5.14 Principal and Emergency Spillway 11 Sand Filter (pdf)
11.1 General Characteristics and Purpose
11.4 Maintenance
11.4.1 Common Maintenance Issues
11.4.3 Reduction of Pollutants Entering BMPs
11.4.4 Stabilization of BMP Drainage Area 12 Bioretention (pdf)
12.3.1 Retreatment Options
12.3.6 Step 6: Size the Underdrain
12.3.8 Step 8: Select Plants and Mulch
12.4 Common Maintenance Issues 13 Filter Strip (pdf)
13.5 Maintenance
14 Grassed Swale (pdf)
14.2 Meeting Regulatory Requirements
14.5 Maintenance 15 Restored Riparian Buffers (pdf)
15.2 Meeting Regulatory Requirements
16 Infiltration Devices (pdf)
16.2 Meeting Regulatory Requirements 17 Dry Extended Detention Basin (pdf)
17.1 General Characteristics and Purpose
17.2 Meeting Regulatory Requirements
17.3 Design
17.3.2 Siting Issues
17.3.6 Sediment Accumulation
17.3.8 Outlet Design
17.3.9 Dam Safety
17.3.10 Underground Detention Material Specifications
17.4 Maintenance
17.4.1 Common Maintenance Issues
17.5.13 Blockage of Outlets
17.5.14 Principal and Emergency Spillway 18 Permeable Pavement Systems (pdf)
19 Rooftop Runoff Management (pdf)
19.1 General Characteristics and Purpose
19.2 Meeting Regulatory Requirements
19.5 Maintenance 20 Proprietary Systems (pdf)
20.1 General Characteristics and Purpose
20.2 Meeting Regulatory Requirements
APPENDIX A City of Greensboro Links (pdf)
APPENDIX 1 Depth-Duration-Frequency Table for Greensboro, NC (pdf)
APPENDIX 2 Pond Detention Storage Computations (pdf)
APPENDIX 3 Dam Safety Law of 1967 (pdf)
APPENDIX 4 BMP Design Check List (pdf)
APPENDIX 5 BMP Certification Requirements (pdf)
APPENDIX 6 BMP Inspection and Maintenance Check List (pdf)
APPENDIX 7 Preliminary BMP Capital Cost Estimates (pdf)
APPENDIX 8 Stormwater BMP Bonding Process (pdf)
APPENDIX 9 Recommended Guidance for Riser and Barrel Spillway Discharge Characteristics and Flood Routing (pdf)
APPENDIX 10 Buffer Bubble (pdf)
Link to State BMP Manual
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