Stormwater 101 Ohio Lake Erie Commission Best Local Land Use Practices Kirby Date, AICP

Storm Water Topics Water Quantity Water Quantity Water Quality Water Quality Stream and Ditch Restoration and Management Stream and Ditch Restoration and Management Storm water regulation (Ohio EPA) Storm water regulation (Ohio EPA) Runoff reduction and Low Impact Development Runoff reduction and Low Impact Development

The Basics – Concepts: Water Quantity Runoff: amount of precipitation and infiltration Runoff: amount of precipitation and infiltration Travel time: slope, flow depth/length, and roughness Travel time: slope, flow depth/length, and roughness Peak Discharge: Runoff, Travel Time, Watershed Size, Development Location, Timing of Rainfall, Storage Effect Peak Discharge: Runoff, Travel Time, Watershed Size, Development Location, Timing of Rainfall, Storage Effect Time of Concentration: Time from farthest reach to output point Time of Concentration: Time from farthest reach to output point

Water Quantity ctd. Impervious Surface: surface with minimal infiltration Impervious surface model: 5 to 8 % change triggers degradation of watercourses

Water Quantity ctd. Bank Storage: storage and release within stream or ditch bank Bank Storage: storage and release within stream or ditch bank Connection to floodplain is best Connection to floodplain is best Flat subwatersheds are more sensitive to stormwater increases than those with terrain Flat subwatersheds are more sensitive to stormwater increases than those with terrain

Recommended Practices: Water Quantity Increase Infiltration, Reduce Speed, and Increase Storage (increase travel time) (mimic pre-development conditions): Reduce impervious surface, increase perviousness Reduce impervious surface, increase perviousness Improve storage and release on-site Improve storage and release on-site Increase roughness Increase roughness Decentralize/reduce concentration of flow Decentralize/reduce concentration of flow Take advantage of bank storage Take advantage of bank storage Connect stream to floodplain Connect stream to floodplain

The Basics – Concepts: Water Quality Sediments: construction runoff, soil disturbance, stream erosion Sediments: construction runoff, soil disturbance, stream erosion Nutrients: fertilizers, septic/animal wastes Nutrients: fertilizers, septic/animal wastes Bacteria: sewer overflows, septic/animal wastes Bacteria: sewer overflows, septic/animal wastes Debris: dumping, sewer overflows Debris: dumping, sewer overflows Hazardous wastes: poor storage, poor separation, inappropriate use of materials Hazardous wastes: poor storage, poor separation, inappropriate use of materials

Water Quality ctd. BOD – Biological Oxygen Demand Nutrients in water ABSORB oxygen as they break down Aquatic life suffers

Recommended Practices: Water Quality Minimize soil disturbance Minimize soil disturbance Minimize water quantity increases in streams and ditches Minimize water quantity increases in streams and ditches Filter and settle out sediments and contaminants Filter and settle out sediments and contaminants Vegetate stream and ditch corridors Vegetate stream and ditch corridors Improve storage and separation of materials Improve storage and separation of materials Maintain septic systems Maintain septic systems Prevent illicit discharges and dumping Prevent illicit discharges and dumping

Stream/Floodplain Restoration Habitat: vegetation, temperature, hydrology, water quality Habitat: vegetation, temperature, hydrology, water quality Stream hydrology: meanders, pools, riffles, floodplain Stream hydrology: meanders, pools, riffles, floodplain Engineering: stream section, relationship to flow patterns of drainage area, floodplain Engineering: stream section, relationship to flow patterns of drainage area, floodplain Oxbow River and Stream Restoration

Agricultural Ditch Enhancement Approximate stream morphology: 2-stage or hybrid section Approximate stream morphology: 2-stage or hybrid section Minimize “maintenance” Minimize “maintenance” Vegetate Vegetate

Stormwater Management BMPs Require Stormwater Pollution Prevention Plans on development sites Require Stormwater Pollution Prevention Plans on development sites Require developers to control the volume, rate, and quality of stormwater coming off sites (pre-development condition) Require developers to control the volume, rate, and quality of stormwater coming off sites (pre-development condition) Require good quality installation, and use of low-maintenance facilities Require good quality installation, and use of low-maintenance facilities Decentralize stormwater collection and conveyance Decentralize stormwater collection and conveyance Minimize stream crossings Minimize stream crossings Retain and restore natural stream function Retain and restore natural stream function Enhance function of existing agricultural ditches Enhance function of existing agricultural ditches

Roles in Storm Water Regulation Ohio EPA: Water quality: If disturbing > 1 acre, EPA requires SWPPP Ohio EPA: Water quality: If disturbing > 1 acre, EPA requires SWPPP Local government must address water quantity issues Local government must address water quantity issues SWCDs and watershed groups may be involved in erosion/sediment control, storm water management plan reviews SWCDs and watershed groups may be involved in erosion/sediment control, storm water management plan reviews

Runoff Reduction: What The total volume of storm water reduced through: canopy interception, canopy interception, soil infiltration, soil infiltration, evaporation, evaporation, rainfall harvesting, rainfall harvesting, engineered infiltration, engineered infiltration, extended filtration or extended filtration or evapotranspiration. evapotranspiration.

Runoff Reduction: How 1. Early Site Assessment 1. Early Site Assessment 2.Maximize Forest Canopy 2.Maximize Forest Canopy 3.Conserve Soils and Contours 3.Conserve Soils and Contours 4.Minimize Impervious Cover 4.Minimize Impervious Cover 5.Utilize Rooftop Runoff 5.Utilize Rooftop Runoff 6.Front yard bioretention 6.Front yard bioretention 7.Dry Swales 7.Dry Swales 8.Linear Wetlands 8.Linear Wetlands 9.Stream Corridor Management 9.Stream Corridor Management

BMPs: Non-Structural Conservation Development Conservation Development Stream and Wetland Setbacks Stream and Wetland Setbacks Minimize disturbance in design Minimize disturbance in design Retain original trees and plant cover Retain original trees and plant cover Reduce parking requirements Reduce parking requirements Provide open space for Bioretention Provide open space for Bioretention

BMPs: Structural Infiltration50 to 90% Bioretention40 to 80 Pervious Pavers45 to 75 Green Roof45 to 60 Dry Swale40 to 60 Rain Tanks/Cisterns 40+ Roof-downspout Disconnection 25 to 50 Grass Channel15 to 30 Dry Pond0 to 15 Wet Pond0 Sand Filter0 Runoff Reduction, in % Source: CSN and CWP

Infiltration Rain Gardens Rain Gardens Site infiltration Site infiltration

Bioretention

Pervious Pavements

Green Roofs

Dry Swale Source: CSN

Downspout Disconnection Source: CSN

Linear Wetlands Source: CSN

Grass Filter Strip

Grass Channel Source: CSN

Wet Ponds Natural drainage basins (wet ponds with natural edge) Natural drainage basins (wet ponds with natural edge)

Additional practices Catch Basin Insert Catch Basin Insert Rain Tanks/Cisterns Rain Tanks/Cisterns Source: CSN

A Few Resources Center for Watershed Protection, Center for Watershed Protection, Chesapeake Stormwater Network (CSN) Chesapeake Stormwater Network (CSN) Chagrin River Watershed Partners, Chagrin River Watershed Partners,

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