tools and case studies for green-gray lifecycle cost analysis · city of columbus stormwater...

Tools and Case Studies forGreen-Gray Lifecycle Cost Analysis

ASCE Spring Seminar April 2018Justin Kerns

ms consultants

April 2018 ASCE Spring Seminar | Green-Gray Cost Analysis 2

EPA National Stormwater Calculator

Low Impact Development (LID) Controls

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Included LID Controls• Disconnection (rooftop downspouts)• Rain Harvesting (rain barrel or cistern)• Rain Gardens• Green Roofs• Street Planters• Infiltration Basins• Permeable Pavement

April 2018 ASCE Spring Seminar | Green-Gray Cost Analysis


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Included LID Controls• Disconnection (rooftop downspouts)• Rain Harvesting (rain barrel or cistern)• Rain Gardens• Green Roofs• Street Planters• Infiltration Basins• Permeable Pavement

Modeling Capabilities• Hydrologic Analysis• Cost Analysis• Climate Scenarios


Location and Project Information

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• Site Name• Search for Site Location• Site Area


Soil Type

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• NRCS Web Soil Survey• Defined by Hydrologic

Soil Group• Group A – Sand• Group B – Sandy Loam• Group C – Clay Loam• Group D – Clay


Soil Drainage

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• NRCS Web Soil Survey• Saturated Hydraulic

Conductivity


Topography

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• NRCS Web Soil Survey• Surface Slope


Precipitation

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• Measured at nearbyNational WeatherService rain gage

• Average annual rainfallbased on long-termhistorical data


Evaporation

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• Measured at nearbyNational WeatherService weather station

• Monthly evaporationrates calculated fromlong-term historical data


Climate Scenarios

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• Climate projectionsproduced by the WorldClimate ResearchProgramme (WCRP)

• Scenarios model futurechanges in temperatureand precipitation


Climate Scenarios

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• Climate projections affect the average monthly rainfall• Three scenarios• Two time periods


Climate Scenarios

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Climate Scenarios

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Land Cover

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Select the percent of sitearea covered by:

• Forest• Meadow• Lawn• Desert• Impervious



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Select percent ofimpervious area to betreated by each LID type

Enter design storm to beused for LID sizing


LID Controls

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Rain Gardens• Ponding Height• Soil Media Thickness• Soil Media Conductivity• % Capture Ratio

(ratio of LID area todesired captured area)


LID Controls

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Street Planter• Ponding Height• Soil Media Thickness• Soil Media Conductivity• Gravel Bed Thickness• % Capture Ratio



LID Controls

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Permeable Pavement• Pavement Thickness• Gravel Layer Thickness• % Capture Ratio



LID Controls

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Site Suitability• Physical Obstructions• Utility Conflicts• Ease of Access

Impacts• Construction Cost• Maintenance Cost


LID Controls

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Select cost region



LID Controls

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Select cost region



LID Controls

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Select cost region


Model Options

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• Select number of yearsto analyze

• Enter event threshold• Consecutive Days


Results

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• Compare multiplescenarios at once


Results

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Site Description


Results

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Summary


Results

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Rainfall / RunoffEvents


Results

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Rainfall / RunoffFrequency


Results

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Rainfall / RetentionFrequency


Results

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Runoff by RainfallPercentile


Results

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Extreme EventRainfall / Runoff


Results

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Capital Cost(tabular)


Results

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Capital Cost(graphical)


Results

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Maintenance Cost(tabular)


Results

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Maintenance Cost(graphical)


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Quantifying Costs

Traditional Costs• Capital Costs• Maintenance Costs

Indirect Costs• R/W Acquisition Costs• Treatment Plant Costs• Snow removal• Water Re-Use• Energy Savings• Tax Incentives / Utility Fees


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Quantifying Costs

Traditional Costs• Capital Costs• Maintenance Costs

Indirect Costs• R/W Acquisition Costs• Treatment Plant Costs• Snow removal• Water Re-Use• Energy Savings• Tax Incentives / Utility Fees

Non-Monetary Costs• Air Quality• Water Quality• Habitat Quality


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Franklin County Correctional Facility

23 Acre SiteBuildingParking LotLandscaping


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Lifecycle Cost AnalysisTraditional Stormwater Gray Infrastructure• Asphalt Parking Lot• Storm Sewer• Catch Basins• Detention Basin• Maintenance (30 Years)


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Lifecycle Cost AnalysisTraditional Stormwater Gray Infrastructure• Asphalt Parking Lot• Storm Sewer• Catch Basins• Detention Basin• Maintenance (30 Years)

Low Impact Development Green Infrastructure• Permeable Pavers• Storm Sewer• Catch Basins• Detention Basin• Maintenance (30 Years)


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Lifecycle Cost AnalysisTraditional Stormwater GrayInfrastructure• Capital Cost = $1,350,000• Maintenance Cost (30 years) = $430,000• Total = $1,780,000

Low Impact Development GreenInfrastructure• Capital Cost = $1,710,000• Maintenance Cost (30 years) = $380,000• Total = $2,090,000


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Lifecycle Cost AnalysisCity of Columbus StormwaterUtility Fee• Based on property’s contribution to

stormwater runoff• 2,000 SF Impervious Area = 1 ERU

(Equivalent Residential Unit)• 23 Acres Impervious = 500 ERU• Annual Stormwater Fee = $27,040• 30 Year Fee = $811,200• GI used to meet all water quality and

quantity requirements = 100% credit


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Lifecycle Cost AnalysisTraditional Stormwater GrayInfrastructure• Capital Cost = $1,350,000• Maintenance Cost (30 years) = $430,000• Stormwater Fee (30 years) = $811,000• Total = $2,590,000

Low Impact Development GreenInfrastructure• Capital Cost = $1,710,000• Maintenance Cost (30 years) = $380,000• Total = $2,090,000


Questions?

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Justin Kernsms consultants, inc.2221 Schrock Rd,

Columbus, OH 43229614-898-7100

[email protected]


tools and case studies for green-gray lifecycle cost analysis · city of columbus stormwater...

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