Stormwater 101Stormwater 101

Ohio Lake Erie CommissionOhio Lake Erie Commission

Best Local Land Use Best Local Land Use PracticesPractices

Kirby Date, AICPKirby Date, AICP

Storm Water TopicsStorm Water Topics

Water QuantityWater Quantity Water QualityWater Quality Stream and Ditch Restoration and Stream and Ditch Restoration and

ManagementManagement Storm water regulation (Ohio EPA)Storm water regulation (Ohio EPA) Runoff reduction and Low Impact Runoff reduction and Low Impact

DevelopmentDevelopment

The Basics – Concepts: The Basics – Concepts: Water QuantityWater Quantity

Runoff: amount of Runoff: amount of precipitation and precipitation and infiltrationinfiltration

Travel time: slope, flow Travel time: slope, flow depth/length, and depth/length, and roughnessroughness

Peak Discharge: Runoff, Peak Discharge: Runoff, Travel Time, Watershed Travel Time, Watershed Size, Development Size, Development Location, Timing of Location, Timing of Rainfall, Storage EffectRainfall, Storage Effect

Time of Concentration: Time of Concentration: Time from farthest reach Time from farthest reach to output pointto output point

Water Quantity ctd.Water Quantity ctd.

Impervious Impervious Surface: surface Surface: surface with minimal with minimal infiltration infiltration

Impervious surface Impervious surface model: 5 to 8 % model: 5 to 8 % change triggers change triggers degradation of degradation of watercourseswatercourses

Water Quantity ctd.Water Quantity ctd. Bank Storage: Bank Storage:

storage and release storage and release within stream or within stream or ditch bankditch bank

Connection to Connection to floodplain is bestfloodplain is best

Flat subwatersheds Flat subwatersheds are more sensitive are more sensitive to stormwater to stormwater increases than increases than those with terrainthose with terrain

Recommended Practices:Recommended Practices:Water QuantityWater Quantity

Increase Infiltration, Reduce Speed, and Increase Infiltration, Reduce Speed, and Increase Storage (increase travel time) Increase Storage (increase travel time) (mimic pre-development conditions):(mimic pre-development conditions):

Reduce impervious surface, increase Reduce impervious surface, increase perviousnessperviousness

Improve storage and release on-siteImprove storage and release on-site Increase roughnessIncrease roughness Decentralize/reduce concentration of flowDecentralize/reduce concentration of flow Take advantage of bank storageTake advantage of bank storage Connect stream to floodplainConnect stream to floodplain

The Basics – Concepts:The Basics – Concepts:Water QualityWater Quality

Sediments: construction Sediments: construction runoff, soil disturbance, runoff, soil disturbance, stream erosionstream erosion

Nutrients: fertilizers, Nutrients: fertilizers, septic/animal wastesseptic/animal wastes

Bacteria: sewer overflows, Bacteria: sewer overflows, septic/animal wastesseptic/animal wastes

Debris: dumping, sewer Debris: dumping, sewer overflowsoverflows

Hazardous wastes: poor Hazardous wastes: poor storage, poor separation, storage, poor separation, inappropriate use of inappropriate use of materialsmaterials

Water Quality ctd.Water Quality ctd.

BOD – Biological BOD – Biological Oxygen DemandOxygen Demand

Nutrients in water Nutrients in water ABSORB oxygen as ABSORB oxygen as they break downthey break down

Aquatic life suffersAquatic life suffers

Recommended Practices:Recommended Practices:Water QualityWater Quality

Minimize soil disturbance Minimize soil disturbance Minimize water quantity increases in Minimize water quantity increases in

streams and ditches streams and ditches Filter and settle out sediments and Filter and settle out sediments and

contaminantscontaminants Vegetate stream and ditch corridorsVegetate stream and ditch corridors Improve storage and separation of Improve storage and separation of

materialsmaterials Maintain septic systemsMaintain septic systems Prevent illicit discharges and dumpingPrevent illicit discharges and dumping

Stream/Floodplain Stream/Floodplain RestorationRestoration

Habitat: vegetation, Habitat: vegetation, temperature, temperature, hydrology, water hydrology, water qualityquality

Stream hydrology: Stream hydrology: meanders, pools, meanders, pools, riffles, floodplainriffles, floodplain

Engineering: stream Engineering: stream section, relationship section, relationship to flow patterns of to flow patterns of drainage area, drainage area, floodplainfloodplain

Oxbow River and Stream Restoration

Agricultural Ditch Agricultural Ditch EnhancementEnhancement

Approximate stream morphology: 2-Approximate stream morphology: 2-stage or hybrid sectionstage or hybrid section

Minimize “maintenance”Minimize “maintenance” VegetateVegetate

Stormwater Management Stormwater Management BMPsBMPs

Require Stormwater Pollution Prevention Plans Require Stormwater Pollution Prevention Plans on development siteson development sites

Require developers to control the volume, rate, Require developers to control the volume, rate, and quality of stormwater coming off sites (pre-and quality of stormwater coming off sites (pre-development condition)development condition)

Require good quality installation, and use of low-Require good quality installation, and use of low-maintenance facilitiesmaintenance facilities

Decentralize stormwater collection and Decentralize stormwater collection and conveyanceconveyance

Minimize stream crossingsMinimize stream crossings Retain and restore natural stream function Retain and restore natural stream function Enhance function of existing agricultural ditchesEnhance function of existing agricultural ditches

Roles in Storm Water Roles in Storm Water RegulationRegulation

Ohio EPA: Water quality: If Ohio EPA: Water quality: If disturbing > 1 acre, EPA requires disturbing > 1 acre, EPA requires SWPPP SWPPP

Local government must address Local government must address water quantity issueswater quantity issues

SWCDs and watershed groups may SWCDs and watershed groups may be involved in erosion/sediment be involved in erosion/sediment control, storm water management control, storm water management plan reviewsplan reviews

Runoff Reduction: WhatRunoff Reduction: What

The total volume of storm water The total volume of storm water reduced through: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: HowRunoff Reduction: How 1. Early Site Assessment1. Early Site Assessment 2.2. Maximize Forest CanopyMaximize Forest Canopy 3.3. Conserve Soils and ContoursConserve Soils and Contours 4.4. Minimize Impervious CoverMinimize Impervious Cover 5.5. Utilize Rooftop RunoffUtilize Rooftop Runoff 6.6. Front yard bioretentionFront yard bioretention 7.7. Dry SwalesDry Swales 8.8. Linear WetlandsLinear Wetlands 9.9. Stream Corridor ManagementStream Corridor Management

BMPs: Non-StructuralBMPs: Non-Structural

Conservation DevelopmentConservation Development Stream and Wetland SetbacksStream and Wetland Setbacks Minimize disturbance in designMinimize disturbance in design Retain original trees and plant coverRetain original trees and plant cover Reduce parking requirementsReduce parking requirements Provide open space for BioretentionProvide open space for Bioretention

BMPs: BMPs: StructuralStructural

Infiltration 50 to 90%

Bioretention 40 to 80

Pervious Pavers 45 to 75

Green Roof 45 to 60

Dry Swale 40 to 60

Rain Tanks/Cisterns

40+

Roof-downspout Disconnection

25 to 50

Grass Channel 15 to 30

Dry Pond 0 to 15

Wet Pond 0

Sand Filter 0

Runoff Reduction, in %

Source: CSN and CWP

InfiltrationInfiltration

Rain GardensRain Gardens Site infiltrationSite infiltration

Bioretention Bioretention

Pervious PavementsPervious Pavements

Green RoofsGreen Roofs

Dry SwaleDry Swale

Source: CSN

Downspout Downspout DisconnectionDisconnection

Source: CSN

Linear WetlandsLinear Wetlands

Source: CSN

Grass Filter StripGrass Filter Strip

Grass ChannelGrass Channel

Source: CSN

Wet PondsWet Ponds

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

Additional practicesAdditional practices

Catch Basin InsertCatch Basin Insert Rain Rain

Tanks/CisternsTanks/Cisterns

Source: CSN

A Few ResourcesA Few Resources

Center for Watershed Protection, Center for Watershed Protection, www.cwp.orgwww.cwp.org

Chesapeake Stormwater Network Chesapeake Stormwater Network (CSN) (CSN) www.chesapeakestormwater.netwww.chesapeakestormwater.net

Chagrin River Watershed Partners, Chagrin River Watershed Partners, www.crwp.orgwww.crwp.org

Questions?Questions?

Kirby Date, AICPKirby Date, AICP

Tel. 216-687-5477Tel. 216-687-5477

k.date@csuohio.eduk.date@csuohio.edu