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
[email protected]@csuohio.edu
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