Successful Green Infrastructure Planning: A Micro-Scale Modeling and Field Investigation Approach Hazem Gheith and Vinnie Treatment, Water Division, ARCADIS-US Hunter Kelly, Department of Sewage and Drainage, City of Columbus OWEA Conference 2013 Imagine the result
Topics City of Columbus Integrated Plan IP Pilot Area: Upper Olentangy basin Grey Solution Green Solution Green Infrastructures SWMM Modeling Results and Recommendations 2 Imagine the result
Topics City of Columbus Integrated Plan IP Pilot Area: Upper Olentangy basin Grey Solution Green Solution Green Infrastructures SWMM Modeling Results and Recommendations 3 Imagine the result
City of Columbus Integrated Plan Local Models Pilot Areas and Early Action Projects Affordability Analysis SSCM 2012 Model Update IP Steering Committee Public Outreach Integrated Plan System Wide Model Stormwater Strategic Plan and WQ Analysis Satellite Communities 4 Imagine the result
Integrated Plan Modeling Approach RDII Planning Sanitary Model Storm Model GI Planning Investigate RDII Sources Construct Sanitary Model Construct Storm Model Investigate Surface Runoff RDII Reduction Technologies Calibrate H/H Model Calibrate H/H Model GI Technologies Define Base Hydraulic Deficiencies Base Flow Condition Define Base Hydraulic Deficiencies Impact on SSOs and WIBs Alternatives Plan Evaluation RDII Reduction Plan Additional flow between Systems Storm Reduction Plan Impact on Stormwater Deficiencies GREY Cost Benefit Analysis Hybrid IP Alternative GREEN 5 Imagine the result
City of Columbus WWMP Status Two Consent orders 2002: Remediation to SSOs 2004: Remediation to CSOs WWMP 2005 40 years schedule Three Tunnels Local storages Storm redirection projects OEPA approved WWMP in 2009 2012: OEPA approved to delay ART and ORT. An integrated Plan is due in September 2015. 6 Imagine the result
Topics City of Columbus Integrated Plan IP Pilot Area: Upper Olentangy basin Grey Solution Green Solution Green Infrastructures SWMM Modeling Results and Recommendations 7 Imagine the result
Pilot Area: Upper Olentangy Basin: WWMP Solution OSIS has seven CSO regulators within the Upper Olentangy Basin Five regulators are active in typical year storms City of Columbus was planning to implemented the WWMP solutions: Four local storage tanks at Frambes, Indianola, King and Third Regulators Inflow redirection at First Ave regulator (started) OSIS 8 Imagine the result
Pilot Area: Upper Olentangy Basin Enhanced Grey Solution Alternative 1: Storages at Indianola and King Regulators Increase capture pipe at Frambes and Third Regulators Alternative 2: One Storage at Indianola Regulator Increase capture pipe at Frambes and Third Regulators Raise weir at King Regulator 9 Imagine the result
Pilot Area: Upper Olentangy Basin Green Infrastructure Solution Successful GI program should: Capture 65 MGD of runoff (TY storms) Has low cost to offset the cost of the local storages Six basins totaling 830 acres of surface runoff (16-293 acres) CSO activations are due to: Excessive runoff from the six basins Limited capture pipe capacity High water levels in OSIS (limiting flow discharge from the basins) OSIS backing up into CSO regulators 10 Imagine the result
GI Challenges Unique challenges in the study area: Limited open spaces Disturbance to old trees Small-scale GI units Portion of the area is within The OSU Existing utility conflicts 11 Imagine the result
Where and what GI Technology? Peak flow should be captured or attenuated before it discharges into the storm inlets Constraints Flow levels (low and high) Availability of suitable sites Detailed site evaluation and high resolution hydrology model were both the key for the proposed GI program 65 MGD runoff reduction is needed to eliminate TY CSOs Peak Flow Contribution at inlet catchments Site Availability Constraints 12 Imagine the result
Peak Flow Constraints Inlet catchments Peak Flows Typical year storms 50% of the catchments receive a maximum of 0.5 MGD. GI units could be oversized GI placed in large runoff catchments may be filled at early stage of storms impeding their impact to attenuate peak flows 13 Imagine the result
Peak Flow Constraints Identify contiguous clusters of high peak flow catchments Ease planning the CIPs Allow interaction (hydraulic connectivity) between the GI units to maximize benefits 14 Imagine the result
Site Constraints: Rain Gardens Needs long streets to allow for a train of RG units to have measurable impact on large peak flows Should be placed at distances to avoid disturbance to pedestrian 15 Imagine the result
Site Constraints: Porous Curbs and Gutters (PCG) Streets with shallow slope topology to maximize storage Good sites are assumed to have 1% or less street slopes PCG units are assumed to have 3.5-ft width, extended along both sides of the street 16 Imagine the result
Site Constraints: Sidewalks If applicable, PCG are extended to include sidewalks Only if sidewalk is within 1- ft from the curb Avoid disturbance to old trees 17 Imagine the result
Site Constraints: Subsurface Detentions (SSD) SSD is assumed to be placed at the downstream end of alleys, prior to intersection with a street SSD was limited to low traffic alleys that sloped down to a street The alley must not contain a sewer close to the SSD location 18 Imagine the result
Site Constraints: Alley Detentions (AD) Alley detentions are assumed to replace both sides of alley edges with a porous material overlaying a 2-ft gravel layer Constraints: Requires low slope topology Low traffic Most of the Alleys meet the criteria 19 Imagine the result
Site Constraints: Permeable Alleys Alley should not contain sewers Low surface slope to increase storage and infiltration efficiency Limited application because most alleys contain a sewer 20 Imagine the result
Site Constraints: Permeable Streets Assumed to be used only in the on-street parking lanes Low traffic Street should not contain sewers Low surface slope to increase efficiency 21 Imagine the result
Inlet Catchment GI Application List 22 Imagine the result
Topics City of Columbus Integrated Plan Pilot Area: Upper Olentangy basin Grey Solution Green Solution Green Infrastructures SWMM Modeling Results and Recommendations 23 Imagine the result
Surface Runoff Challenges Runoff surfaces Roofs draining to street Splashing over lawn Connected to sewer Commercial Lawn Alleys Side walks Parking lots Street and drive ways Traditional Catchment Delineation Levels Manhole level Storm Inlet level 24 Imagine the result
Limitations in Traditional Runoff Catchment Delineation Runoff Input Parameters Area % Impervious Width Slope Manning Depression Storage Infiltration Impervious Pervious Receiving Manhole Some Challenges One slope value for all features within the catchment One sheet flow width value for all features One abstraction value for all impervious surfaces Etc. 25 Imagine the result
Enhanced SWMM Modeling Resolution Split the catchment into subareas representing the true runoff configuration House Roofs Discharging to curb lines Discharging onto lawns Directly connected to sewers Lawns discharging to streets Alleys discharging to streets Commercial roofs discharging to parking lots Parking Lots discharging to collectors Drive ways and street discharging to storm inlets House Roofs (discon.) House Roofs (to street) Commerc ial Roof House Roofs (connect.) Alleys Parking Combined Manhole Outfall Lawns Driveways / Streets Storm Inlet 26 Imagine the result
Computed Max Flow (mgd) Enhanced Delineation Improves Calibration Several parameters are known (roofs slope, roofs flow length, roofs depression storage, streets and alley slopes and flow length, etc.) Faster calibration since most parameters are known Computed vs Observed Max Flow (mgd) at Link 0053C2782:0053C0603 13 12 11 10 Error: ISE rating ISE R² SEE LSE LSE dim RMSE RMSE dim 0053C2782:0053C0603 Excellent 1.76 0.964 0.436 12.7 1.12 2.58 0.144 20% 9 8 7 6 5 4 3 2 1 0 0 2 4 6 8 10 12 Observed Max Flow (mgd) 27 Imagine the result
Flow (mgd) Better Understanding of Flow Configuration Enhanced Model Traditional Model DoeAlley_NewDelineation Link 0086C0132:0086C0133 0086C0132:0086C0133 DoeAlley_Recal_Hazem 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 5AM Jun 14 Sat 2008 6AM 7AM 8AM 9AM Date/Time 28 Imagine the result
Subareas Flow Volume Contribution 587 storm inlet catchments in Upper Olentangy Basin Streets and Alleys contribute 50% of the total runoff volume Surface Type Runoff Area (AC) Runoff Volume June 6, 1981 (MG) % of Total Runoff Volume Roof Connected 32.00 1.58 6.1% Roof Disconnected 101.34 5.01 19.4% Roof Drain to Streets 15.36 0.76 2.9% Roof Commercial 29.01 1.41 5.4% Lawns 296.60 2.48 9.6% Parking Lots 34.52 1.52 5.9% Alley 116.52 5.32 20.6% Street 165.71 7.81 30.2% Total 791.06 25.88 100% 29 Imagine the result
Topics City of Columbus Integrated Plan Pilot Area: Upper Olentangy basin Grey Solution Green Solution Green Infrastructures SWMM Modeling Results and Recommendations 30 Imagine the result
GI Program for Upper Olentangy Basin Rainfall Urbanized land Collection System Receiving Waters Goal 1: Optimize GI units: Maximize inflows Maximize attenuation Minimize size Optimize placement to maximize benefit Rain Gardens Porous Curbs & Gutters Porous Sidewalks Goal 2: Achieve WWF control at key points in the collection system (CSO activation) Infiltration 31 Imagine the result
Dynamic Routing Solution using SWMM Rain Gardens: 3.5 ft x 10 ft every 50 ft House Roofs (discon.) House Roofs (to street) Lawns Porous Curb and Gutters 3.5-ft width, extended along both sides of the street Alleys RG P C G Drive Ways / Streets If applicable, PCG were extended to include sidewalks Only if sidewalk is within 1-ft from the curb Commerc ial roof House Roofs (connect.) Parking Combined Manhole Storm Inlet Outfall 32 Imagine the result
Complementary Grey Solution for Upper Olentangy Basin Raise weir at King Ave Regulator Permanently block the diversion between Third/Henry Regulator Basins Impact on WIBs was studied up to 10-yr LOS storm No potential for new WIBs Conclusion was to block the 18 connection pipe Third Ave Regulator Split Henry St. Regulator 33 Imagine the result
Grey versus Green/Grey Infrastructure Cost 30-Year NPV Life Cycle Cost Category Gray Alternative (2 local storage facilities) Medium Range Cost Green Alternative (RGs, PCG, PSW) Medium Cost Range Capital Cost $35M $57.1M Ongoing O&M $9M $7.5M Residue Value & Social and Environmental Benefits Total Cost/Benefit ($13M) ($36.8M) $31M $27.8M 34 Imagine the result
Conclusion A green infrastructure program in the Upper Olentangy basins with minimal grey improvements could offset the need of local storage facilities An educated approach utilizing GIS tools windshield surveys helped optimizing site selection for the different GI units A higher resolution modeling approach is critical in understanding the dynamic performance and sizing GI units 35 Imagine the result
Thank You Imagine the result 36 Imagine the result