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Climate Risk and Resilience Planning for Wastewater Infrastructure Laurens van der Tak, PE, D.WRE VWEA Education Seminar – Managing Risk through Process and Organizational Innovation May 12, 2016 Presentation Outline Climate Change Threats Adaptation Strategy Framework Climate Change Adaptation Case Studies Miami-Dade Water and Sewer Department Boston Water and Sewer Commission 2 Climate Change Threats: Rainfall, Extreme Storms and Sea Level Rise - Impacts Vary Based on System Function and Source (Drainage, Riverine, and Coastal) Precipitation Sea level rise Storm surge Precipitation timing, 2- to 10-year storms Stormwater/Drainage Management 3 Localized flooding Increased CSOs 100-year storms Riverine Floodplain Management Regional flooding Tidal flooding Tropical storms Climate Change will make storms we design for more intense, and increase the frequency (ie risk) of exceeding design criteria for flood protection. Precipitation Precipitation timing, 10-year storm depth will increase by about 1 inch A 100-yr becomes 50yr recurrence 4 Adaptation Framework: When dealing with future uncertainty an adaptive planning process provides needed flexibility. 5 Steps to identify strategies to increase resilience to sea level rise: 11 2 3 Frame the Identification of ProblemVulnerabilities Frame the Problem “What are the overarching questions to answer and sea level rise scenarios to plan for, with the goal of increasing resilience to sea level rise?” and Risk “What are the overarching Identify and assess questions to answer and infrastructure that may be sea level rise scenarios impacted byto sea level rise. plan for, with the goal of increasing resilience to sea level rise?” 6 4 Develop a list of potential adaptation strategies Determine the range of strategies that will provide the best adaptation to changing future conditions based on identified vulnerabilities. Link adaptation strategies to current process Review adaptation strategies to identify those that only require an adjustment or modification to current policies or programs. 5 6 Implement Adaptation Strategies Identify priority strategies for implementation: those strategies that are best aligned with the values, goals and objectives of the implementing organization . Continually Monitor and Re-assess Monitor sea level rise, revisit assessments and re-assess priority strategies to continually inform future actions to adapt to changes in sea level. A problem well-defined, is a problem half solved. ~Charles Kettering • Are facilities near tidal waters, subject to sea level rise and storm surge? 1 Frame the Problem “What are the overarching questions to answer and sea level rise scenarios to plan for, with the goal of increasing resilience to sea level rise?” • Are my operations at risk of riverine flooding or greater I/I from sea level rise and higher rainfall? • Are my operations at risk from power outages? • What is the planning horizon for evaluating climate change: – Service life of assets – CIP planning cycle, based on growth, land use change, finances • Select climate scenarios based on your risk tolerance: – Consider low, medium and/or high future scenarios 7 Scenario analysis…accounting for future uncertainty 160 140 Sea Level Rise Scenarios Precautionary Trend 100-cm (3.3-ft) Sea level above 2010, cm 120 100 80 60 Historic Trend 40-cm (1.3-ft) 40 20 0 2010 2020 2030 2040 2050 2060 2070 2080 2090 2100 Year 8 Extrapolated Historic Trend Line Curve 1 (2100 End Point = 70 cm) Curve 2 (2100 End Point = 100 cm) Curve 3 (2100 End Point = 140 cm) Curves adapted from the NC Coastal Resources Commission Science Panel on Coastal Hazards 2010 NC Sea Level Rise Assessment Report (March 2010) Steps to identify strategies to increase resilience to sea level rise: 2 1 Frame the Problem “What are the overarching questions to answer and sea level rise scenarios to plan for, with the goal of increasing resilience to sea level rise?” 9 4 Develop a list of potential adaptation strategies Identification of Vulnerabilities and Risk Determine the range of strategies that will provide the best adaptation to changing future conditions based on identified vulnerabilities. Identify and assess infrastructure that may be impacted by sea level rise. Link adaptation strategies to current process Review adaptation strategies to identify those that only require an adjustment or modification to current policies or programs. 5 6 Implement Adaptation Strategies Identify priority strategies for implementation: those strategies that are best aligned with the values, goals and objectives of the implementing organization . Continually Monitor and Re-assess Monitor sea level rise, revisit assessments and re-assess priority strategies to continually inform future actions to adapt to changes in sea level. Asset Inventory and Risk Evaluations provide a strong foundation for CC Vulnerability Assessments • Identify major asset types of interest, e.g.: 2 – Wastewater treatment plants Identification of Vulnerabilities and Risk Identify and assess infrastructure that may be impacted by sea level rise. – Wastewater pump stations – Gravity sewers and manholes – Force mains • Define the critical elevations for these assets • Identify vulnerable assets. • Define probability of inundation events and likelihood of damage. • Determine consequence of failure. • Determine risk level: high, medium, and low risk groupings. 10 Climate risk builds on asset management information to understand critical assets Driven by Asset Management program data Asset Characterization Susceptible Assets Vulnerable Elevations Damage Thresholds Consequence of Failure Hazard Characterization Sea Level Rise Scenarios Extreme Events 11 Vulnerability: Risk = P(Event)* [P(Damage)*P(Consequence)] Adaptation Options Climate risk builds on asset management information to understand critical assets Asset Characterization Susceptible Assets Vulnerable Elevations Damage Thresholds Consequence of Failure Hazard Characterization Sea Level Rise Scenarios Extreme Events 12 Vulnerability: Risk = P(Event)* [P(Damage)*P(Consequence)] Adaptation Options Climate Vulnerability Assessment Relies on Asset Inventory and Risk Assessment WWTP Electrical Building At Risk from 100-yr storm surge and 100 cm SLR 13 Manhole Risk Identification Climate risk builds on asset management information to understand critical assets SLR Impacts on Wilmington NC Asset Characterization Susceptible Assets Vulnerable Elevations Damage Thresholds Consequence of Failure Hazard Characterization Sea Level Rise Scenarios Extreme Events Vulnerability: Risk = P(Event)* [P(Damage)*P(Consequence)] • SLR Hazards = SLR scenario x event • SLR scenarios 40 cm rise – historic trends scenario 100 cm rise – precautionary scenario • Events 14 Mean higher high water (MHHW) 10-year flood elevation 100-year flood elevation Adaptation Options Adaptation Strategies for Improving Flood Resilience Adaptation Strategies for Stormwater Management and Flood Protection Systems Grey Solutions: • • • • • • • • • 15 DC Water Blue Plains Flood Wall Source: Umair Irfan, eenews.net Green Solutions: • • • • Raising electrical and mechanical equipment Sealing wall penetrations Water tight doors Adding tide gates to outfalls Backup generators Barriers or local surge walls Adding capacity to the drainage network Moving flows from one part of the system to another Emergency response planning Green infrastructure Coastal wetlands Renewable energy and Co-generation Zoning and Land Use Planning Phasing adaptations to account for uncertainty in projections and risk tolerance Water Street GI, Onondaga NY Climate Change Case Studies • NACWA: Confronting Climate Change Report to Congress • City of Wilmington, NC • NYCDEP – Wastewater Resiliency Plan • Boston Water and Sewer Commission • North Carolina Sea Level Rise Risk Management • USEPA Climate Adaptation Strategies Guide • City of Alexandria, VA • Fairfax VA, Master Plan • LA Bureau of Sanitation • California Bay-Delta • Colorado River Basin Study • Berwick, ME • Miami-Dade Water and Sewer Department 16 Miami-Dade Water and Sewer Department 17 MIAMI-DADE COUNTY WATER AND SEWER DEPARTMENT Preliminary Facility Hardening Plan Ocean Outfall Legislation Program OOL Compliance Projects 19 Climate Resilience/Facility Hardening- Objectives and General Approach • Assess projected climate change for key climate variables (sea level rise, precipitation, wind, inundation due to surge) • Define critical wastewater assets and risk due to climate change • Define design criteria to minimize risk • Develop facility hardening plans and design guidelines for WASD design teams 20 Findings/Recommendations: •Climate Projections •Facility Hardening Design Guidelines 21 Precipitation IDF Projections Impacts: Peak Flows and Flooding WASD Pump Station Peak Flows Are Based on 2-yr Storm: • Historically: 4.5” (SFWMD, 2001) • Updated: 4.9” (2014) • Projected: 5.4” to 6” (2040 to 2100) 20 Precipitation (Inches) 18 16 14 12 10 Updated Historical NOAA Atlas 14 2040 RCP 6.0 50% 2040 RCP 8.5 50% 2075 RCP 6.0 50% 2075 RCP 8.5 50% 2100 RCP 6.0 50% 2100 RCP 8.5 50% 8 6 18.74 17.42 16.83 16.26 15.84 15.49 14.51 14.48 9.60 8.829.189.00 8.268.038.578.68 4.694.894.774.804.844.934.885.04 4 2 0 2 10 Return Period (Years) 22 Source: CH2M / CLIMsystems, January 2015 100 2-year 24-hour Precipitation Projections (Design Criteria for Peak Sewer Flows): Implications for PS 187 RCP, % nonexceedance 2-Year 24hr Rainfall (inches) % Change in Rainfall Peak Flow Rate (mgd) “Current” 4.5 0% 151 0% 2040 RCP6.0/8.5, 50% 4.8 7% 155 3% 2040 RCP8.5, 90% 5.42 20% 167 11% 2075 RCP6.0, 90% 5.58 24% 171 13% 2075 RCP8.5, 90% 6.05 34% 180 19% Horizon % Change in flow 5.42 inch, 2040 projection selected based on service life of PS 23 23 Precipitation for 2075: Flooding Impacts, Particularly Coupled with Coastal Storm Surge 100-yr 24hr storm projected to increase from 14.5” to 17.4” – 20” 24 Stressor: Sea Level Rise Impacts: Coastal Flooding and Increased I/I (due higher GW) Source: SE FL Climate Compact, DRAFT April 2015 25 Surge Modeling: Modeled Result Comparison of Peak Surge Elevation (mNGVD) 26 Surge Modeling: Modeled Result Distribution of boundary Peak Surge Elevations: 100yr condition Red: 100yr + 1.23m SLR 0 Transect Location Blue: Peak Surge Elevation (mNGVD) 1O1 2O2 3O3 4O4 5O5 6O6 7O7 8O8 9O9 10 10O 11 11O 12 12O 13 13O 14 14O 15 15O 16 16O 17 17O 18 18O 19 19O 20 20O 21 21O 22 26O 23 29O 1 2 3 4 5 6 NDWWTP CDWWTP CDWWTP SDWWTP Ocean Bay 27 Projected Stillwater Elevations: Surge+2075 SLR+2075 Extreme Rainfall 100-yr 28 100-yr + SLR Findings/Recommendations: •Climate Projections •Facility Hardening Design Guidelines 29 Factors in Setting Risk-based Design Criteria will be used to evaluate cost/benefit of facility hardening • Planning Horizon to establish the service life: – 2075 for Critical Long-Term Facilities (e.g. WWTPs) – 2040 selected for pump station flows (e.g. PS-1) • Criticality, based on wastewater or pumping facility function, such as: – Maintenance of facility hydraulics – Maintenance of equivalent primary treatment, liquid train – Maintenance of secondary treatment, liquid train – Maintenance of solids treatment – Ancillary facilities, such as administration and laboratory buildings 30 30 Factors in Setting Risk-based Design Criteria will be used to evaluate cost/benefit of facility hardening • Level of protection: – NOAA (High) SLR curve – USACE (High) SLR curve • Level of Freeboard: – 2 ft for WWTP vs Pump Stations in Coastal Flood Zones, ie. FEMA Zone V (ASCE Standard 24-05/2010 FBC Category IV) – 1 ft for WWTP vs Pump Stations in Inland Flood Zones, ie. FEMA Zones A, AE (ASCE Standard 24-05/2010 FBC Category III) • Level of Safety Factor: – 0 ft for low risk facilities, or – 1 ft as set by WASD at CDWWTP 31 31 Facility Hardening Costs were Developed for Critical Facilities above Design Flood Elevation 32 Adaptation Strategies / Protective Measures Identified site-specific protective measures to minimize prolonged service interruption and flood risk, while balancing feasibility, resiliency, and cost. Establish robust design guidelines for future wastewater infrastructure upgrades/designs that assist in mitigating flood risk. Elevate Equipment on pads or platforms, to a higher floor, to the roof, or to a new elevated building. Flood-Proof Equipment by replacing pumps with submersible pumps and installing watertight boxes around electrical equipment. Install Static Barrier across critical flood pathways or around critical areas. Seal Building with water-tight doors and windows, elevating vents and secondary entrances for access during a flood event. Sandbag Temporarily around doorways, vents, and windows before a surge event. 33 Install Backup Power via generators nearby or a plug for a portable generator. Does not protect equipment but facilitates rapid service recovery. Source: NYCDEP Facility Hardening Costs - WWTPs Scenario 1 (Design Elevation 16.0 ft) CD OOL (Existing Total Scenario 2 (2075 SLR + FB + SF) CD $ 4,576,200 $ 4,576,200 $ 39,947,600 CDWWTP 5,513,000 $ 16,053,000 $ SDWWTP $ 1,533,000 $ 3,980,000 $ NDWWTP $ 9,213,000 $ 9,213,000 $ 14,578,000 Note: $ 19,302,200 OOL Facility hardening was only estimated for retrofitting existing facilities. New OOL facilities would be hardened to same design criteria. 34 OOL (Existing Facilities) $ 7,650,000 $ $ $ Total 39,947,600 23,703,000 14,578,000 78,228,600 Facility Hardening Design Guidelines for Existing and New WWTP Assets WWTP Summary of Design Criteria for Hardening against Flooding from Surge, Sea Level Rise and Extreme Storm Events. Existing WWTP Facility Assets New WWTP Facility Assets ft NGVD29 Basis ft NGVD29 Basis CDWWTP 16.0 FEMA BFE + 3ft SLR from SEFLCC(2011) +FB +SF 20.3 2075 Surge+1.23m(48")SLR + FB +SF+21”(100-yr, 72-hr rainfall) SDWWTP 16.0 FEMA BFE + 3ft SLR from SEFLCC(2011) +FB +SF 19.0 2075 Surge+1.23m(48")SLR + FB +SF+21”(100-yr, 72-hr rainfall) NDWWTP 16.0 Same as CDWWTP and SDWWTP 17.1 2075 Surge+1.23m(48")SLR + FB +SF+21”(100-yr, 72-hr rainfall) FB= Freeboard = 2.0 ft per ASCE Standard 24-05/2010 FBC Category IV SF= Safety Factor = 1.0 ft per 2014 MWH study at CDWWTP SLR = 1.23m = 48" per NOAA High projection for 2075 (USACE High projection is 0.93m) 35 Boston Water and Sewer Commission 36 Climate Change Risks • Increased Rainfall • Increased river flows and flooding – Charles River, Neponset River and Mystic River may flood areas of the City during storms • Sea Level Rise and Storm Surge 37 Forecasted 10-year, 24-hour Design Storm Volumes and Peak Hourly Intensities A recalculation of historical rainfall through 2012 indicated that their 4.8-inch design storm has increased to 5.2 inches Total Storm Volume (inches) Peak Hourly Intensity (inches per hour) Scenario 2035 2060 2100 2035 2060 2100 Medium (B2) 5.55 5.76 6.08 1.76 1.83 1.93 Precautionary (A1FI) 5.60 6.03 6.65 1.78 1.91 2.11 BWSC’s current design standard is 4.8 inches 38 Climate change is increasing the size and intensity of this design storm and it could be 6.65 inches by 2100. Copyright © 2014 Boston Water and Sewer Commission 980 Harrison Ave. Boston, MA 02119 617-989-7000 Sea Level Rise Projections Storm Surge Heights held Constant with Today Source: Vermeer & Rahmstorf, 2009 Medium SLR Projections through 2100 Return Period (years) Boston (mm) Boston (m) Boston (ft) 2 868 0.87 2.85 5 1,067 1.07 3.50 10 1,194 1.19 3.92 20 1,311 1.31 4.30 50 1,457 1.46 4.78 100 1,562 1.56 5.12 200 1,664 1.66 5.46 500 1,793 1.79 5.88 1,000 1,887 1.89 6.19 Precautionary SLR Projections through 2100 Component 2035 2060 2100 Component 2035 2060 2100 Global (feet) 0.79 1.54 3.51 Global (feet) 1.21 2.20 6.20 Subsidence (feet) 0.08 0.16 0.30 Subsidence (feet) 0.08 0.16 0.30 0 0 0 Regional (feet) 0.23 0.39 0.66 0.87 1.70 3.81 Total (feet) 1.52 2.75 7.16 Regional (feet) Total (feet) 39 Copyright © 2014 Boston Water and Sewer Commission 980 Harrison Ave. Boston, MA 02119 617-989-7000 Evaluated Flooding Risks to Sewer Systems • Models of the Storm Drain and Sewer Systems (SWMM) to Calculate Flows Now and in The Future • 2-dimensional computer models (CH2M’s Flood Modeler-FAST) to map surface flooding due to drainage and storm surge 40 Copyright © 2014 Boston Water and Sewer Commission 980 Harrison Ave. Boston, MA 02119 617-989-7000 Flood Modeler Simulation of Hurricane Sandy Source: Douglas, et. al. 2013. 41 Copyright © 2014 Boston Water and Sewer Commission 980 Harrison Ave. Boston, MA 02119 617-989-7000 Risks Of Flooding With Sea Level Rise And Storm Surge – Year 2060 with 10-year/24-hour Rainfall Year 2060 Rain Year 2060 Rain Sea Level Rise, No Storm Surge Sea Level Rise, With Storm Surge 42 Copyright © 2014 Boston Water and Sewer Commission 980 Harrison Ave. Boston, MA 02119 617-989-7000 43 BWSC PUMP STATION (FACILITY ID) MWRA Copyright © 2014 Boston Water and Sewer Commission 980 Harrison Ave. Boston, MA 02119 617-989-7000 Port Norfolk (11LPS316) Austin Street (27JPS1) Symphony Hall (21IPS1) MWRA DeLauri (MWRA002) Union Park (21KPS2) Summer Street (22MPS5) Public Alley 701 (21JPS526) Trilling Way (22MPS2) Caruso (29NPS4) MWRA Prison Point (MWRA003) Commonwealth Ave (22IPS1) Sullivan Square (29JPS1) MWRA Cottage Farm (MWRA001) TOTAL RISK (0-100) Pump Station Risk Scoring for Precautionary 2100 Scenario with Storm Surge Pump Station Total Risk Score for P2100 with Storm Surge (23.50 feet) 100 90 80 70 60 50 40 30 20 10 0 Future Condition Without and With Flood Walls Precautionary 2060 Precautionary 2060 With Flood Walls Flooding due to SLR and storm surge only, no rainfall in these calculations 44 Copyright © 2014 Boston Water and Sewer Commission 980 Harrison Ave. Boston, MA 02119 617-989-7000 Drainage Would Still Have to be Addressed Precautionary 2060 With Flood Walls and 10-year/24-hour rainfall Additional mitigations beyond flood walls along shorelines would be needed to prevent street flooding should a significant rainfall occur during a storm surge event in the future 45 Copyright © 2014 Boston Water and Sewer Commission 980 Harrison Ave. Boston, MA 02119 617-989-7000 Update Design Storm for Drainage and Conveyance Engineering, Planning and Design • 10-year/24-hour design storm – 5.20 inches (instead of 4.80 inches) – Peak hourly intensity of 1.65 inches per hour • For life cycles through the year 2100: – Consider range from 5.55 inches to 6.65 inches – Depending on the life cycle starting and end date. • Other Recommendations – Annual rainfall should range from 50.0 to 55.4 inches by the year 2100 – Apply to CSO control and TMDL planning – Apply to operations and maintenance planning – Continually monitor and update rainfall statistics 46 Copyright © 2014 Boston Water and Sewer Commission 980 Harrison Ave. Boston, MA 02119 617-989-7000 Design Flood Elevations (DFEs) to Protect Facilities and Operations Recommended DFEs for Pump Stations and other Structures Project Life cycles up to the Year (feet – Boston City Base) Design Condition 2035 2060 2100 Minimum 18.22 19.06 21.16 Higher Risk Mitigation 18.88 20.11 24.50 Recommended DFEs are based on: • The current MHHW elevation of 11.23 feet • Sea Level Rise • 100-year storm surge of 5.12 feet • 1-foot freeboard 47 Apply to: • Construction of new infrastructure • Capital improvements to existing infrastructure • Tide gates Copyright © 2014 Boston Water and Sewer Commission 980 Harrison Ave. Boston, MA 02119 617-989-7000 New York City DEP 48 NYC Wastewater Resiliency Plan Strategy: Protect wastewater treatment facilities Adopt a wastewater facility design standard Harden pumping stations and wastewater treatment plants Explore opportunities to expand cogeneration 49 Critical Flood Elevations 50 26th Ward 12.6 13.5 12.9 Brooklyn-Sewer Bowery Bay 11.6 15.5 13.9 Queens Coney Island 10.1 15.5 14.0 Brooklyn-Highway Hunts Point 10.2 17.5 16.0 Bronx Jamaica None 13.5 11.9 Queens Newtown Creek 10.0 13.5 12.0 Brooklyn-Highway North River 9.7 12.5 10.8 Manhattan Port Richmond 12.1 14.5 12.4 Staten Island Oakwood Beach 13.1 16.5 14.4 Staten Island Owls Head 13.5 14.5 13.0 Brooklyn-Highway Red Hook 11.7 14.5 13.0 Brooklyn-Highway Rockaway 11.4 14.5 12.9 Queens Tallman Island 10.1 15.5 13.9 Queens Wards Island 10.7 17.5 15.8 Manhattan Building-Level Risk Assessment Performed site visits and analyzed each facility for flood pathways and threshold elevations. Locations identified as at-risk if threshold elevations are below the assigned flood elevation (100-yr ABFE + 30-inches SLR). Common Flood Pathways: Rollup Doors 51 Tunnels Doorways & Windows Areaways Grates Electrical Conduits and Manholes Asset-Level Risk Assessment Target Assets include: • Equipment associated with primary treatment • Electrical equipment • Pumps and motors Target asset identified as at-risk- situated below the assigned flood elevation (100-yr ABFE + 30 inches SLR), and are not submersible. Electrical assets located underground in the RAS Gallery at 26th Ward WWTP are at risk of flood damage. 52 NYCDEP Wastewater Resilience Plan Comparison of Mitigation Costs and Cost of No Action (ie Benefits of Mitigation) Adaptation Cost No Action Cost Risk Avoided Over 50 years Source: NYCDEP All 53estimates are based on AACE Level 5 Cost Estimate guidelines as noted in the NYCDEP BEDC Cost Estimating Manual Thank You