Knox County Tennesee

• 1.1 Impacts of Development and Stormwater Runoff
  • 1.1.1 Development Changes Land and Runoff
  • 1.1.2 Changes to Stream
  • 1.1.3 Changes to Stream Geometry
  • 1.1.4 Impacts to Aquatic Habitat
  • 1.1.5 Water Quality Impacts
  • 1.1.6 Stormwater Hotspots
  • 1.1.7 Effects on Ponds, Lakes and Reservoirs
• 1.2 Addressing Stormwater Impacts
• 1.3 Comprehensive Stormwater Management Planning
• 1.4 Minimum Stormwater Management Standards
• 1.5 Stormwater Quality Treatment Rationale

• 2.1 Integrated Site Design Approach
  • 2.1.1 Introduction
  • 2.1.2 General Design Policies and Guidance
• 2.2 Stormwater Quality Management
  • 2.2.1 General Requirements and Policies
  • 2.2.2 Percent TSS Removal Values for Structural BMPs
  • 2.2.3 Calculation of WQv and %TSS Removal
  • 2.2.4 Calculation of %TSS Removal for BMPs in Series
  • 2.2.5 The Measurement and Calculation of Percent Imperviousness
  • 2.2.6 Reducing the WQv
• 2.3 Channel Protection (CPv)
  • 2.3.1 Background
  • 2.3.2 Design Criteria and Policies
• 2.4 Stormwater Quantity Management
  • 2.4.1 Overbank Flood Protection Criteria (Qp25)
  • 2.4.2 Extreme Flood Protection (Qp100)
  • 2.4.3 Downstream Impact Analysis
• 2.5 Stormwater Conveyance Design
  • 2.5.1 General Criteria
  • 2.5.2 Pipe Systems
  • 2.5.3 Roadway Culverts
  • 2.5.4 Open Channels
  • 2.5.5 Outlet Protection
  • 2.5.6 Gutters and Inlets

• 3.1 Introduction to Hydrologic Methods
  • 3.1.1 Symbols and Definitions
  • 3.1.2 Rainfall Estimation
  • 3.1.3 Rational Method
  • 3.1.4 Regression Methods
  • 3.1.5 SCS Hydrologic Method
  • 3.1.6 Clark Unit Hydrograph
  • 3.1.7 Water Quality Calculations
  • 3.1.8 Water Balance Calculations
  • 3.1.9 Calculating Downstream Impacts (the Ten Percent Rule)
• 3.2 Storage Design
  • 3.2.1 General Storage Concepts
  • 3.2.2 Symbols and Definitions
  • 3.2.3 General Storage Design Procedures
  • 3.2.4 Preliminary Detection Calculations
  • 3.2.5 Calculation of the Channel Protection Volume
• 3.3 Outlet Structures
  • 3.3.1 Symbols and Definitions
  • 3.3.2 Primary Outlets
  • 3.3.3 The Design of Extended Detention Outlets
  • 3.3.4 Multi-Stage Outlet Design
  • 3.3.5 Trash Racks and Safety Grates
  • 3.3.6 Secondary Outlets

• 4.1 Design Standards Policy
• 4.2 BMP Description and Selection Information
  • 4.2.1 General Application BMPs
  • 4.2.2 Limited Application BMPs
  • 4.2.3 Pollutant Removal Capabilities
  • 4.2.4 Screening Process for General Application BMPs
  • 4.2.5 Limited Application BMP Screening Process
  • 4.2.6 Off-Line Versus On-Line Structural BMPs
  • 4.2.7 Using Structural Stormwater BMPs in Series
• 4.3 General Application Stormwater BMPs
  • 4.3.1 Stormwater Ponds
  • 4.3.2 Conventional Dry Detention
  • 4.3.3 Dry Extended Detention Ponds
  • 4.3.4 Stormwater Wetlands
  • 4.3.5 Bioretention Areas
  • 4.3.6 Sand Filters
  • 4.3.7 Infiltration Trench
  • 4.3.8 Enhanced Swales
  • 4.3.9 Filter Strip
  • 4.3.10 Grass Channel
  • 4.3.11 Modular Porous Paver System
  • 4.3.12 Porous Pavement
• 4.4 Limited Application Stormwater BMPs
  • 4.4.1 Organic Filter
  • 4.4.2 Underground Sand Filter
  • 4.4.3 Submerged Gravel Wetlands
  • 4.4.4 Alum Treatment System
  • 4.4.5 Proprietary Structural BMPs
  • 4.4.6 Underground Detention
  • 4.4.7 Oil-Grit (Gravity) Separator

• 5.1 Introduction
• 5.2 Water Quality Volume (WQv) Credits
  • 5.2.1 Introduction
  • 5.2.2 Site Planning Using Stormwater Site Design Credits
  • 5.2.3 General Policies for WQv Credits
  • 5.2.4 Credit #1: Natural Area Conservation
  • 5.2.5 Credit #2: Managed Open Space Preservation
  • 5.2.6 Credit #3: Stream and Vegetated Buffers
  • 5.2.7 Credit #4: Use of Vegetated Channels
  • 5.2.8 Credit #5: Impervious Area Disconnection
  • 5.2.9 Credit #6: Environmentally Sensitive Large Lot Neighborhoods
• 5.3 Better Site Design Practices
  • 5.3.1 Overview
  • 5.3.2 Incorporating Better Site Design Practices into Site Design Process
  • 5.3.3 Discussion of Better Site Design Practices
  • 5.3.4 Conservation of Natural Features and Resources
  • 5.3.5 Low Impact Site Design Techniques
  • 5.3.6 Reduction of Impervious Cover
  • 5.3.7 Using Natural Features for Stormwater Management
  • 5.3.8 Better Site Design Examples

• 6.1 Introduction
• 6.2 Applicability
  • 6.2.1 Community Waters Definition
• 6.3 Buffer Zones and Widths
  • 6.3.1 Zones
  • 6.3.2 Widths
  • 6.3.3 Width Requirements for Steep Slopes
• 6.4 Vegetation and Enhancement Requirements
  • 6.4.1 Inner Zone (Streams and Wetlands)
  • 6.4.2 Outer Zone (Streams and Ponds/Lakes)
  • 6.4.3 Non-native and Invasive Vegetation Buffer Enhancement Requirements
• 6.5 Water Quality Buffer Averaging
  • 6.5.1 Requirements and Policies
  • 6.5.2 Areas Where Buffer Averaging is Prohibited
  • 6.5.3 Example Calculation
• 6.6 Use of Buffer Areas
  • 6.6.1 Prohibited Uses
  • 6.6.2 Allowable Uses in the Inner Zone
  • 6.6.3 Allowable Uses in the Outer Zone
• 6.7 Allowable Disturbances
  • 6.7.1 Inner Zone
  • 6.7.2 Outer Zone
• 6.8 Protection of Water Quality Buffers
  • 6.8.1 During Construction
  • 6.8.2 After Construction
  • 6.8.3 Signage
• 6.9 Level Spreaders
• 6.10 Conflicts with State Requirements

• 7.1 Stormwater Drainage System Design
  • 7.1.1 Drainage System Components
  • 7.1.2 Checklist for Drainage Planning and Design General Drainage Design Standards
• 7.2 Storm Drain Pipe Systems
  • 7.2.1 Design Standards and Considerations
  • 7.2.2 General Design Procedure
  • 7.2.3 Capacity Calculations
  • 7.2.4 Hydraulic Grade Lines
  • 7.2.5 Minimum Grade
• 7.3 Culvert Design
  • 7.3.1 Symbols and Definitions
  • 7.3.2 Design Standards and Considerations
  • 7.3.3 Design Procedures
  • 7.3.4 Culvert Design Example
  • 7.3.5 Design Procedures for Beveled-Edged Inlets
  • 7.3.6 Flood Routing and Culvert Design
• 7.4 Open Channel Design
  • 7.4.1 Open Channel Types
  • 7.4.2 Symbols and Definitions
  • 7.4.3 Design Standards and Considerations
  • 7.4.4 Manning's "n" Values
  • 7.4.5 Uniform Flow Calculations
  • 7.4.6 Critical Flow Calculations
  • 7.4.7 Vegetative Design
  • 7.4.8 Riprap Design
  • 7.4.9 Gradually Varied Flow
  • 7.4.10 Rectangular, Triangular, and Trapezoidal Open Channel Design
• 7.5 Energy Dissipation Design
  • 7.5.1 Overview
  • 7.5.2 Symbols and Definitions
  • 7.5.3 Design Guidelines
  • 7.5.4 Riprap Aprons
  • 7.5.5 Riprap Basins
  • 7.5.6 Baffled Outlets
  • 7.5.7 Level Spreaders
• 7.6 Minor Drainage System Design
  • 7.6.1 Introduction and General Criteria
  • 7.6.2 Symbols and Definitions
  • 7.6.3 Street and Roadway Gutters
  • 7.6.4 Stormwater Inlets
  • 7.6.5 Grate Inlet Design
  • 7.6.6 Curb Inlet Design
  • 7.6.7 Combination Inlets
• 7.7 Bridge Hydraulics
  • 7.7.1 Bridge Hydraulics Concepts
  • 7.7.2 Computer Applications

• 8.1 Introduction
• 8.2 Applicable Federal Regulations
  • 8.2.1 National Flood Insurance Program
  • 8.2.2 Community Rating System
• 8.3 Local Floodplain Management Tools
  • 8.3.1 FEMA Flood Insurance Studies
  • 8.3.2 Knox County Engineering Floodplain Mapping
  • 8.3.3 Stormwater Master Plans
• 8.4 Floodplain Management Regulations
  • 8.4.1 Summary of Ordinance Requirements for Development in Floodplains
  • 8.4.2 Requirements for Land Use and Land Disturbance
  • 8.4.3 Requirements for Engineering Studies
  • 8.4.4 Requirements for Construction in Floodplains
• 8.5 Regulations for Development in Sinkhole Areas
  • 8.5.1 Background
  • 8.5.2 Regulations and Policies

• 9.1 TN Construction General Permit
• 9.2 General Principles
• 9.3 Regulations and Policies
  • 9.3.1 General
  • 9.3.2 Protection of Water Quality Buffers
  • 9.3.3 Stabilization of Disturbed Areas
  • 9.3.4 Off-Site Sedimentation
  • 9.3.5 Construction Sequencing
  • 9.3.6 Structural Controls
  • 9.3.7 Special Requirements for Impaired or High Quality Streams
  • 9.3.8 Cut and Fill Slopes
  • 9.3.9 Construction Exits
  • 9.3.10 Good Housekeeping Practices
• 9.4 Erosion Prevention and Sediment Control Plans
  • 9.4.1 Plan Modifications
• 9.5 Deficient Performance
• 9.6 Inspections and Maintenance
• 9.7 Small Lot EPSC Plans

• 10.1 Overview
• 10.2 Special Pollution Abatement Permit

Volume 2

Appendix