Iowa Stormwater Management Manual
The following table of contents includes links to Version 1 (dated February 19, 2007) of the Iowa Stormwater Management Manual. The manual will be updated from time to time as review of the text and sample problems take place. Some sections remain to be developed.
All the documents are pdf files.
2A General Information 363 kb
2A-1 General Information 78 kb pdf
- Concept
- Overview of stormwater discharges
- Pollutants in urban stormwater
- Management of stormwater quality and quantity
- Permit requirement overview
2A-2 Planning and Design Principles 189 kb pdf
- Project scope and analysis
- Developing a stormwater management plan
- Planning and design principles
- Planning and design conditions
- Floodplain management
2A-3 Stormwater Regulations and Permitting 67 kb pdf
- Introduction
- Regulated activities
- Requirements for regulated MS4s
- Stormwater management programs
2A-4 Stormwater Management Criteria 56 kb pdf
- Development criteria
- Minimum stormwater management guidelines
- Minor and major design storms
- Design frequencies for conveyance facilities
- Street flow criteria
2A-5 Project Drainage Report 57 kb pdf
- Purpose
- Instructions for preparing report
- Contents
2B Unified Sizing Criteria 209 kb
2B-1 Unified Sizing Criteria 209 kb pdf
- General information
- Rainfall frequency spectrum (RFS)
- Water quality volume (WQv)
- Recharge volume requirements (Rev)
- Channel protection storage volume requirements (CPv)
- Overbank flood protection volume requirements (Qp)
- Extreme flood volume (Qf)
2C Stormwater Hydrology
2C-1 General Information for Stormwater Hydrology 100 kb pdf
- Introduction
- Definitions
- Concepts
- Methods of runoff estimation
2C-2 Rainfall and Runoff Analysis 162 kb pdf
- Introduction
- Rainfall frequency analysis
- NRCS 24-hour storm distribution
2C-3 Time of Concentration 320 kb pdf
- Introduction
- Definition
- Factors affecting time of concentration
- Estimating time of concentration (NRCS velocity method)
- Estimating time of concentration (NRCS lag method)
- Design example
2C-4 Rational Method 99 kb pdf
- Introduction
- Characteristics
- Limitations
- Use of the Rational method
- Design example
2C-5 NRCS TR-55 Methodology 400 kb pdf
- Introduction
- Equations and concepts
- Runoff factor
- Urban modifications of the NRCS method
- WINTR-55 for analysis
2C-6 Small Storm Hydrology 297 kb pdf
- Introduction
- Water quality volume and peak flow
- Method for computing the channel protection storage volume
- Maximized water quality capture volume
- Estimating a maximized water quality capture volume
- Design example
2C-7 Runoff Hydrograph Determination 1.2 mb pdf
- Introduction
- Unit hydrographs
- Application of the unit hydrograph method
- Watershed routing (hydrograph determination)
- Tabular hydrograph method
- Design example
2C-8 Low-Impact Development (LID) Hydrology 2.1 mb pdf
- Introduction
- Hydrologic comparison: conventional vs. low-impact development
- LID hydrologic analysis components
- Process and computational procedure
- Determination of design storm event
2C-9 Detention Storage Design 190 kb pdf
- Introduction
- Alternatives for estimating detention volume
- Planning and design alternatives
- Preliminary detention storage design
- Modified Rational method
- Design example
2C-10 Channel and Storage (Reservoir) Routing 497 kb pdf
- Introduction
- Channel routing
- Storage (reservoir) routing
- Stage-storage relationship
- Stage-discharge relationship
- Storage-indication routing
- Detention design procedure with storage routing
- Design example (currently under development)
2C-11 Inlet Sediment Forebays 223 kb pdf
- Introduction
- Water quality
- Channel erosion control and flood control
- Design criteria
2C-12 Detention Basin Outlet Structures 2.3 mb pdf
- Introduction
- Outlet structure types
- Extended detention (water quality and channel protection) outlet design
- Sizing of single-stage risers
- Design of multiple stage outlets
- Extended detention outlet protection
- Trash racks and safety gates
- Secondary outlets
2C-13 Water Balance Calculations 78 kb pdf
- Introduction
- Base equations
2C-14 Downstream Hyrologic Assessment 141 kb pdf
- Introduction
- Reasons for downstream problems
- The ten-percent rule
- Design example
2D BMP Types and Applications 294 kb
2D-1 General Information for BMPs 102 kb pdf
- Description and performance of stormwater BMPs
- Goals of stormwater BMPs
- Pollutant removal process
2D-2 Non-Structural Controls 21 kb pdf
- Education, recycling, and source controls
- Maintenance practices
2D-3 Structural Controls 283 kb pdf
- Structural BMPs
- Structural control categories
- Structural stormwater control pollutant removal capabilities
- Selection guide for structural stormwater controls
- General application control screening process
- Online vs. off-line structural controls
- Onsite vs. regional stormwater management
- Using structural stormwater controls in series
2E Infiltration Practices 5.3 mb
2E-1 General Information for Infiltration Practices 238 kb pdf
- Introduction
- Infiltration fundamentals
- Infiltration systems
- Infiltration hydraulics and process
- Soils and infiltration
- Screening criteria for infiltration practices
- Types of infiltration practices
- Design criteria for infiltration practices
2E-2 Infiltration Trenches 1.6 mb pdf
- Description
- Stormwater management suitability
- Pollutant removal capabilities
- Application and feasibility
- Planning and design criteria
- Physical specifications, geometry, and volume
- Design of infiltration trenches
- Design procedures
- Inspection and maintenance requirements
- Example schematics
- Design example
2E-3 Infiltration Basins 1.8 mb pdf
- Description
- Stormwater management suitability
- Pollutant removal capabilities
- Application and feasibility
- Planning and design criteria
- General design
- Physical specifications, geometry, and volume
- Design of infiltration basins
- Procedures for infiltration basin design
- Maintenance
- Design example
2E-4 Bioretention Systems 1.7 mb pdf
- Description
- Stormwater management suitability
- Pollutant removal capabilities
- Application and feasibility
- Planning and design criteria
- Physical specifications and geometry
- Structures
- Design procedures
- Inspection and maintenance requirements
- Design example
2E-5 Soil Quality Restoration 140 kb pdf
- Description
- Stormwater management suitability
- Pollutant removal capabilities
- Application and feasibility
- Planning and design criteria
- Design procedures
- Inspection and maintenance requirements
- Design example
2E-6 Native Landscaping 77 kb pdf
- Description
- Stormwater management suitability
- Pollutant removal capabilities
- Application and feasibility
- Planning and design criteria
- Design procedures
- Inspection and maintenance requirements
2E-7 Soils Testing Requirements for Infiltration Practices 55 kb pdf
- Definition
- Purpose
- Conditions where practice applies
- Criteria
- Additional considerations
2F Filtration Practices 2.1 mb
2F-1 Sand Filter 1.1 mb pdf
- Description
- Stormwater management suitability
- Pollutant removal capabilities
- Application and feasibility
- Planning and design criteria
- Flow regulation
2F-2 Design of Surface and Perimeter Sand Filter 747 kb pdf
- Physical specifications and geometry
- Pre-treatment/inlets
- Outlet structures
- Auxiliary spillway
- Maintenance access
- Safety features
- Landscaping
- Additional site-specific design criteria and considerations
- Design procedures
- Inspection and maintenance requirements
- Design example
2F-3 Underground Sand Filter 292 kb pdf
- Description
- Pollutant removal capabilities
- Design criteria
- Inspection and maintenance requirements
2G Detention Practices 2.4 mb
2G-1 General Information for Detention Practices 281 kb pdf
- Introduction
- Storage facilities
2G-2 Dry Detention 906 kb pdf
- Description
- Design criteria and physical specifications
- Inspection and maintenance requirements
- Example schematics
2G-3 Wet Detention 1.3 mb pdf
- Description
- Stormwater management suitability
- Pollutant removal capabilities
- Application and feasibility
- Design approach
- Design procedures
- Inspection and maintenance requirements
2H Stormwater Wetlands 1.1 mb
2H-1 General Information for Stormwater Wetlands 1 mb pdf
- Description
- Stormwater managment suitability
- Pollutant removal capabilities
- Application and feasibility
2H-2 Design of Stormwater Wetlands 79 kb pdf
- Planning and design criteria
- General design
- Physical specifications and geometry
- Pre-treatment inlets
- Outlet structures
- Auxiliary spillway
- Maintenance access
- Safety features
- Landscaping
- Additional site-specific design criteria and issues
- Design procedures
- Inspection and maintenance requirements
2I Vegetated Swale Systems 2.1 mb
2I-1 General Information for Vegetated Swale Systems 493 kb pdf
- Introduction
- Types of vegetated practices
- Comparative pollutant removal capability
- Suitability and selection considerations
- Land use factors
- Site conditions
- Flow regulation
- Pre-treatment
2I-2 Grass Swales 840 kb pdf
- Description
- Stormwater management suitability
- Pollutant removal capabilities
- Application and feasibility
- Grass swales for pre-treatment
- Check dams
- Channel design criteria
- Design procedure
- Inspection and maintenance requirements
- Design example
2I-3 Dry and Wet Swales 664 kb pdf
- Description
- Stormwater management suitability
- Pollutant removal capabilities
- Applications and feasibility
- Planning and design criteria
- Design procedure
- Design example
2I-4 Vegetated Filter Strips 283 kb pdf
- Description
- Pollutant removal capabilities
- Design criteria
- Inspection and maintenance requirements
- Design example
2J Pavement Systems
2J-1 General Information for Pavement Systems
Section under development - please refer to other resources
2J-2 Permeable Concrete Pavers
Section under development - please refer to other resources
2J-3 Modular Pavement Systems
Section under development - please refer to other resources
2J-4 Portland Cement Pervious Concrete Pavements
Section under development - please refer to other resources
2J-5 Porous Asphalt Pavement
Section under development - please refer to other resources
2K Mechanical Systems
2K-1 General Information for Mechanical Systems
Section under development - please refer to other resources
2K-2 Hydro-Dynamic Devices
Section under development - please refer to other resources
2K-3 Gravity Separator
Section under development - please refer to other resources
2K-4 Catch Basin Inserts
Section under development - please refer to other resources
2L Chemical Treatment for Turbidity Removal
2L-1 General Information for Chemical Treatment
Section under development - please refer to other resources
2L-2 Coagulation/Flocculation
Section under development - please refer to other resources
2M Storm Sewer Design 818 kb
2M-1 General Information for Storm Sewer Design 23 kb pdf
- Introduction
- Definitions
- Location of storm sewers
- Pipe materials
- Physical requirements
- Horizontal alignment
2M-2 Groundwater Barriers and Outlets 31 kb pdf
- Introduction
- Groundwater barriers
- Outlets
2M-3 Street Flow and Intake /Manhole Capacity 413 kb pdf
- Introduction
- Definitions
- Intercepting flows
- Storm sewer locations
- Intake capacity
- Manhole and intake standards
- Intake capacity design example
2M-4 Storm Sewer Sizing 404 kb pdf
- Introduction
- Flow formulas
- Hydraulic losses
- Hydraulic design of storm sewers
2N Design of Culverts 1.4 mb
2N-1 General Information for Design of Culverts 157 kb pdf
- Introduction
- Definitions
- Site considerations
- Culvert design items
- Design considerations
- Pipe material
- Pipe culvert sizes
- Culvert inlets
- Roadway or street overtopping
- Storage routing
2N-2 Culvert Hydraulics 1.2 mb pdf
- Culvert flow controls and equations
- Inlet and outlet control
- Use of inlet and outlet control nomographs
- Culvert design example
2O Open Channel Flow 553 kb
2O-1 Channel Types and Structures 91 kb pdf
- Introduction
- Channel types
- Drop structures for open channel flow
2O-2 Open Channel Flow 474 kb pdf
- Introduction
- Definitions
- Uniform flow (Mannings Equation)
- Energy flow
- Non-uniform flow
- Hydraulic jump
- Hydraulic jump design example for trapezoidal channel
- Solution nomographs
