Green Infrastructure Modeling in Cincinnati Ohio

Small Scale Green Infrastructure Design Using Computer Modeling

23 September 2014

Presenters

Jason Abbott is a Design Engineer with over 17 years of experience. Jason is a professional engineer with a BS from Ohio State University.

Leah Buerman is a water resources engineer with over 5 years of experience. Leah is a professional engineer with a BS and an M.Eng from Cornell University.

23 September 2014

23 September 2014

Mill Creek & West Fork Branch Watersheds

23 September 2014

West Fork Branch Watershed Characteristics

• 6,000 Acre Watershed• 1,500 Acres Mt. Airy

Forest• 15 CSOs• 12,800 LF of Natural

Channel• 12,000 LF of

Rectangular Concrete Channel• Hydraulically

Connected Through 18 Grated Inlets

23 September 2014

West Fork Branch Sustainable Watershed Project Alternative Analysis Report

23 September 2014

Enabled Impact Projects

“Since 2009, MSD has partnered with public and private entities across Hamilton County to demonstrate the use of effectiveness of various stormwater controls.

This program – known as the Enabled Impact Program –enables MSD to fund or help fund stormwater controls on partner sites”

- MSD Project Groundwork

23 September 2014

TerminologyRain Garden - (also known as bioretention or bioinfiltration cells) shallow, vegetated basins that collect and absorb runoff from rooftops, sidewalks, and streets. Rain gardens mimic natural hydrology by infiltrating and evapotranspiring runoff. Rain gardens are versatile features that can be installed in almost any unpaved space. Bioswale - vegetated, mulched, or xeriscaped channels that provide treatment and retention as they move stormwater from one place to another. Vegetated swales slow, infiltrate, and filter stormwater flows. As linear features, vegetated swales are particularly suitable

along streets and parking lots. Source: EPA http://water.epa.gov/infrastructure/greeninfrastructure/gi_what.cfm

23 September 2014

Green (Enabled) Project Opportunity

Grants• OEPA - SWIF • OEMA• OEPA – Clean OH Partners• Cincinnati Parks Board• Ground Work Cincinnati

- Mill Creek• Northside

23 September 2014

Partnering & Grants – Mt. Airy Wetland Redevelopment

OEPA - Surface Water Improvement Fund (SWIF) Grants Program

23 September 2014

Partnering & Grants – Flood Plain Enhancement

Ohio Emergency Management Agency: Pre-Disaster Mitigation Grant

Clean Ohio Fund: Clean Ohio Green Space Conservation Grant

23 September 2014

Six Enabled Impact Projects Evaluated in the West Fork Branch Sewershed

GOAL: Implement green infrastructure within the community to reduce stormwater runoff and consequently CSO volume at the downstream CSO’s

23 September 2014

Computer Modeling of Enabled Impact ProjectsGOAL: Evaluate the potential reduction in stormwater runoff volume achieved through the implementation of each green infrastructure project. Identify the placement of the most effective and cost efficient green infrastructure within the community• Software: PCSWMM - EPA SWMM 5 (Storm

Water Management Model Version 5) Engine• Rainfall: Typical Year Rainfall - a modified

version of the 1970 rainfall for Cincinnati, Ohio

23 September 2014

Green Infrastructure Modeling Techniques

• Rain Gardens modeled as storage nodes. Void space of the rain garden subbase was included in the total volume of the storage node.

• Bioswale modeled as a trapezoidal channel

• Conservatively minimal infiltration was included in the model at the green infrastructure locations.

Suction Head, in

Hydraulic Soil conductivity (in/hr)

10 0.5 LB1

Slide 14

LB1 ten in of suction head is conservative assumes siilty clay / clay soils. 0.5in Hydraulic soil conductivity is also for clay soilsSuggest that Field testing is preferred to determine soil characteristicsLeah Buerman, 8/22/2014

23 September 2014

Mt. Airy Wetland Redevelopment

23 September 2014

Area 2 – Mt. Airy Wetland RedevelopmentProposed installation of three rain gardens in series located downstream of the Mt. Airy Forest (tributary to CSO 127). Drainage area is currently directly connected to the combined sewer system.Attributes• Drainage Area = 132.5 ac• Proposed Rain Garden Modeled Surface Area = 30,594 sf• Proposed Rain Garden Depth varies from 1.5ft to 4ft• Proposed Rain Garden Total Volume = 53,700 cf• Proposed Rain Garden Storage Volume = 4,269 cf

The volume assumes that only the first 0.5ft of the rain gardens are used for storage.

23 September 2014

Floodplain Enhancement

23 September 2014

Area 4 – Floodplain EnhancementProposed installation of a bioswale and a rain garden in series located near West Fork Road (tributary to CSO 127)Attributes• Drainage Area = 1.3 ac• Proposed Rain Garden Modeled Surface Area = 6,721 sf• Proposed Rain Garden Modeled Depth = 1.5ft• Proposed Rain Garden Total Volume = 10,082 cf• Proposed Rain Garden Storage Volume = 3,361cf

The volume assumes that only the first 0.5ft of the rain gardens are used for storage.

23 September 2014

Modeling ResultsGreenInfrastructure Location

Description Total Annual Runoff Volume, MGExisting Proposed Volume

Reduction

Area 2 Mt. Airy Wetland Redevelopment

22.43 18.5 3.94

Area 4 Floodplain Enhancement

0.51 0.01 0.5

Total: 3.99

Computer modeling can provide the necessary information to help identify the placement of effective and cost efficient green infrastructure within the community. Runoff reduction potential along with installation cost, education benefits, aesthetic improvements, etc. are used to determine GI placement and design.

23 September 2014

Questions