Site Evaluation

2.1  Site Location

2.2  Site Coverage (Pervious versus Impervious Areas)

2.3  Soil Characteristics 

Determine Stormwater Retention Volume

3.0  Required Water Storage Calculations, Water Quality - Treatment Volume Calculation and Water Quantity - Flood Attenuation Calculation

EPA LID Stormwater Evaluation

4.0 EPA LID Stormwater Evaluation and Software

Design LID SWMF By Hand

5.0  LID Options

5.1  Rainwater Harvesting: Rain Barrels and Cisterns

5.2  Bioretention: Rain Garden

5.3  Planter Boxes

5.4  Tree Boxes

5.5  Enhanced Shallow Swales

5.6  Infiltration Trenches

5.7  Pocket Wetlands

5.8  Pervious Pavers, Porous Concrete, Geogrid System

Additional Design Considerations

6.1 - 6.4    Compensating Stormwater Treatment, Overtreatment, Off-site Compensation and Erosion and Sediment Control Criteria

Appendix A - Suggested Plants

References

• ASCE Appendix A-1: Runoff Peak Discharge Calculations. https://www.maine.gov/dep/land/stormwater/stormwaterbmps/vol3/appendixa.pdf
• Environmental Protection Agency. Green Infrastructure Design and Implementation. https://www.epa.gov/green-infrastructure/green-infrastructure-design-and-implementation
• Environmental Protection Agency. Large Volume Storms and Low Impact Development, Using LID Practices in Areas with Intense Rainfall Events. October 2017. https://www.epa.gov/sites/production/files/2017-10/documents/lid_fs10_rainfall_epa_508.pdf
• Florida Department of Environmental Protection. Florida Stormwater Erosion and Sedimentation Control Inspectors Manual. July 2018. http://publicfiles.dep.state.fl.us/DEAR/DEARweb/Stormwater_training/Manual/FSESCI%20TIER%20I%20Manual%20062918.pdf
• Florida Department of Environmental Protection. Florida Stormwater Erosion and Sedimentation Control Inspectors Manual. Tier II: Manual for Best Management Practices (BMP) Inspectors. July 2018. http://publicfiles.dep.state.fl.us/DEAR/DEARweb/Stormwater_training/Manual/FSESCI%20TIER%20II%20Manual%20062918.pdf
• Florida Department of Transportation. FDOT Drainage Design Guide. January 2018. http://www.fdot.gov/roadway/Drainage/files/DrainageDesignGuide.pdf
• Florida Department of Transportation. FDOT Drainage Manual Distribution Curves. Accessed September 13, 2018. http://www.fdot.gov/roadway/Drainage/files/IDFCurves.pdf
• Florida Department of Transportation. Drainage manual Topic No. 625-040-002. Florida Department of Transportation’s (FDOT) Hydrology Handbook (February 2012). 
• Logan, Simpson, et al. Low Impact Development Toolkit Prepared for the City of Mesa Arizona. April 2015. https://www.mesaaz.gov/home/showdocument?id=14999
• National Oceanic and Atmospheric Administration. Hydrometeorological Design Studies Center. NOAA Atlas 14 Point Precipitation Frequency Estimates. https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_map_cont.html
• New York State Department of Environmental Conservation. New York State Stormwater Management Design Manual. October 2001. http://www.tonawanda.ny.us/document-center/technical-support/stormwater-management/368-new-york-state-stormwater-management-design/file.html
• Philadelphia Water Department. Stormwater Management Guidance Manual Porous Pavement. https://www.pwdplanreview.org/manual/chapter-4/4.2-porous-pavement
• SF Permeable Paving Stone Systems. March 31, 2009. https://www.tremron.com/pdf/product_guides/permeable_pavements_design.pdf
• Stormwater Coalition of Albany County. Guidance Manual for Homeowners, Managing Stormwater Runoff Using Green Infrastructure. http://www.stormwateralbanycounty.org/wp-content/uploads/2011/12/GuidanceManual_Homeowners_DwnspoutDisc_RainGarden_RainBarrels1.pdf
• The Clean Water Team Guidance Compendium for Watershed Monitoring and Assessment State Water Resources Control Board 5.1.3 FS-(RC) 2011. http://www.waterboards.ca.gov/water_issues/programs/swamp/docs/cwt/guidance/513.pdf
• The Watershed Center, Grand Traverse Bay. A Natural Solution, An Introduction to Low Impact Development for Commercial and Residential Applications in the Grand Traverse Region.  January 2016. https://www.gtbay.org/wp-content/uploads/2016/01/Low-Impact-Development-guidebook-small.pdf 
• United States Department of Agriculture Natural Resource Conservation Service Web Soil Survey. https://websoilsurvey.nrcs.usda.gov/app/WebSoilSurvey.aspx.

Glossary

Definitions and terms that are not defined herein shall be given their ordinary and customary meaning or usage of the trade or will be defined using published, generally accepted dictionaries, together with any rules and statutes of the Agencies that have additional authority over the regulated activities.

1. 100-year flood/One Percent Annual Chance of Flood - A flood event that has a one percent probability of recurrence in any one year. The 100-year flood elevation is the highest elevation of floodwaters during the 100-year flood and is calculated or estimated from the best available information.
2. Adsorption - The adhesion of a substance to another, generally used in the process of treating water.
3. Attenuation - A reduction in the peak flow originating from a storm event.
4.  Aquitard or Confining-layer - A layer of low permeability material, such as clay or rock, adjacent to an aquifer that functions to prevent the transmission of significant quantities of groundwater flow under normal hydraulic gradients.
5. Berm - A constructed earthen barrier, which serves as a vertical divider with in a stormwater management system.
6. Bioretention - A shallow depression intended for the storage and treatment of stormwater. The area is comprised of vegetation, organic soil, and a filter media such as sand. The system is designed to treat stormwater and allow the settlement of suspended sediment.
7. Capacity - The total volume of a system.
8. Cistern – A large tank used for storing water.
9. Coastal Dune Lake Protection Zone - All lands within an area beginning at the mean or ordinary high water line of the coastal dune lakes and their tributaries and extending 300 feet landward
10. Compatibility – The ability for two or more items or systems to coexist.
11. Control elevation - The lowest elevation at which water can be released through a control device.
12. Design Storm - A specified rainfall event with a specified recurrence interval associated with a recorded rainfall depth over a pre-determined period of time.
13. Erosion - The natural phenomenon of sediment transport generally caused by wind, gravity, water current, or waves. 
14. Evaporation – The phase change of a substance from a liquid to a gas.
15. Floodway - The permanent channel of a stream or other watercourse, plus any adjacent floodplain areas that must be kept free of any encroachment in order to discharge the 100-year flood without cumulatively increasing the water surface elevation more than a designated amount (not to exceed one foot). For purposes of this Manual, this term does not have the same meaning as the term “floodway” or “regulatory floodway” as defined and implemented by FEMA.
16. Geotextile Fabric – A permeable textile material.  The material is manufactured is several varieties, such as woven, nonwoven, or knitted.
17. Hardscape - areas that cannot absorb water; impervious areas.
18. Hydrology - The analysis of water on, under, and over the earth’s surface.
19. Impervious Surface Ratio – The ratio of land cover that does not allow water to move through it in relation to the total area of a parcel.
20. Impervious - A type of ground cover such as pavement that does not absorb water and contributes to sheet flow.
21. Infiltration – The movement of water downward through the soil into groundwater.
22. Initial County Problem Area List (ICPAL) - Areas identified to having significant flooding issues.
23. Inundation - The abundance of water.
24. Ksat -Saturated hydraulic conductivity.
25. Littoral zone - That portion of a stormwater management system that is designed to contain rooted emergent plants.
26. Mitigation - A reduction in severity.
27. Non-Point Source - Pollution such as fertilizers, herbicides, insecticides, sediment, oil and grease that originate from land-use activities.  This type of pollution is carried to nearby stream, rivers, and bays through surface runoff.
28.  Off-line - The storage of a specified portion of the stormwater such that runoff in excess of the specified volume of stormwater does not flow into the area storing the treatment volume.
29. On-line - The storage of a specified portion of the stormwater such that runoff in excess of the specified volume of stormwater flows into or through the area storing the treatment volume.
30. Peak Flow – Cumulative flow accounting for land-use, precipitation intensity, and the total area of the parcel. The peak flow is determined using the Rational equation (Q=ciA).   
31. Permanent pool - that portion of a wet detention pond that normally holds water (e.g., between the normal water level and the pond bottom), excluding any water volume claimed as wet detention treatment volume.
32. Permeability - determines how fast water will be absorbed into the ground.
33. Pervious - A type of ground cover such as natural areas that absorb water.
34. Point Source - An easily identifiable source of pollution entering a nearby waterbody.
35. Porosity - ratio of void volume of total volume; the amount of water that can be stored between sand or stone.
36. Quality - A predetermined standard in which something is compared.
37. Quantity - A definitive numerical value; not an estimate.
38. Rain Barrel - A container used to store stormwater for use in the future.
39. Recovery Rate - How long it takes a stormwater management system to drain.
40. Run off - Excess stormwater that does not immediately infiltrate into the soil.
41. Runoff Coefficient - Dimensionless ratio of rainfall excess to precipitation
42. Saturated Hydraulic Conductivity - a quantitative measurement of the ability for a saturated soil to transmit water.
43. Sediment Transport - The movement of sediment suspended in water.  
44. Silt Fence - A geotextile fence with wooden stakes used as a best management practice employed to contain soil and sediment throughout site disturbance and construction activities.
45. Sheet Flow - Amount of stormwater that is not directly absorbed into the ground, which contributes to the overland flow of stormwater.
46. Sorption - Absorption and adsorption considered as a single process.
47. Stabilization - The act of keeping something from moving or changing.
48. Stormwater Management Facility (SWMF) - A system that is designed and constructed or implemented to control discharges which are necessitated by rainfall events, incorporating methods to collect, convey, store, absorb, inhibit, treat, use, or reuse water to prevent or reduce flooding, over drainage, environmental degradation, and water pollution or otherwise affect the quantity and quality of discharges from the system.
49. Surface Area - The area available for water to infiltrate into the soil.
50. Tailwater - the receiving water elevation (or pressure) at the final discharge point of a stormwater management system.
51. Tidally-Influenced Waterways - Includes surface waters that are characterized by a repeatable monthly average tide range of more than 0.1 feet.
52. Weir - An intentional obstruction traversing the width of a swale or similar stormwater management system specifically designed to hold a predetermined volume of water.
53. Wetlands Stormwater Management System - a stormwater management system that incorporates those wetlands described in section 10.2 of this Volume into the stormwater management system to provide stormwater treatment.
54. Zone A - The area of the swale that will hold the most water. This area requires plants that are tolerant to excess water during the rainy season (typically June through August), as well as, tolerant during dry conditions if it is a dry swale.
55. Zone B - The area along the slopes of a swale. Plants in this region will need to be able to establish robust root systems in order to maintain the design slope and be able to withstand lateral sheet flow during extreme rain events.  They will also need to be able to with survive extended periods of dry conditions with smaller periods of inundation.
56. Zone C - The area along a swale identified as the vegetative strip, this area functions as a pretreatment application to catch sediment and slow down sheet flow.  The plants in this area will need to be able to withstand dry conditions. 

Acronyms

• A                            Area
• ac                          Acres
• AOI                        Area of Interest
• BMP                      Best Management Practice
• c                            Runoff coefficient
• FAC                        Florida Administrative Code
• FDEP                     Florida Department of Environmental Protection
• FDOT                     Florida department of Transportation
• FS                          Florida Statute
• ft                            Feet
• ft2                          Square feet
• ft3                          Cubic feet
• H                           Horizontal
• HSG                       hydraulic soil group
• i                             rainfall intensity
• ICPAL                    Initial County Problem Area List
• IDF                         intensity duration frequency
• in                           Inches
• in/hr                      Inches per hour
• ISR                         Impervious Surface Ratio
• K                            Permeability
• LDC                        Land Development Code
• LID                         Low Impact Design
• NELAP                   National Environmental Laboratory Accreditation Program
• NRCS                     Nature Resource Conservation Service
• NWFWMD            Northwest Florida Water Management District
• O&M                     Operation and Maintenance
• OFW                      Outstanding Florida Waters
• SDWA                   Safe Drinking Water Act
• SHWT                    Seasonal High Water Table
• SMS                      Stormwater management system
• SWMF                   Stormwater Management System
• tc                           Time of Concentration
• Q                           Flow
• V                            Vertical
• V                            Volume
• VT                          Treatment Volume

Appendix C & D - Design Storms and Permitting Guidance