PROTECTING CRITICAL WATER INFRASTRUCTURE FROM SEA LEVEL RISE

Transcription

1 Photo by Dave via Flickr Creative Commons PROTECTING CRITICAL WATER INFRASTRUCTURE FROM SEA LEVEL RISE craig wells, pe McKim & Creed, Inc. curtis burkett, PE McKim & Creed, Inc. Since 1880, sea level has risen 8 inches worldwide, and it continues to rise. The question is not whether sea level rise (SLR) will occur, but how much it will rise and how it will impact our critical water infrastructure. Of the top 10 cities that can expect to have a significant economic impact in the U.S., eight are located in Florida. Yet Florida is ground zero for SLR. Median projections estimate 8 inches of rise in the mean sea level in Florida by 2030, and an additional 24 inches by By 2100, 9% of the total land area of Florida is projected to be submerged at normal high tide. 1 THE IMPACTS OF SLR ON CRITICAL INFRASTRUCTURE INCLUDE: Increased flooding frequency. Saltwater intrusion/contamination into freshwater aquifers that have been the traditional source of drinking water in the state. Continued growth and increased demand will only exacerbate the problem. Increased groundwater levels that render septic tank systems inoperable. Increased flooding at low-lying wastewater treatment facilities, leading to more frequent interruption of treatment operations. Increased infiltration of salt water into wastewater collection systems/pump stations, creating capacity and treatment issues for the facility servicing the collection system. Increased infiltration into reuse distribution systems can render reuse water unsuitable due to high chloride content. Decreased access to critical infrastructure facilities due to flooding. MCKIM & CREED Protecting Critical Water Infrastructure from Sea Level Rise 1

2 The good news is that the cost of making infrastructure resilient to SLR is estimated to be seven to 10 times less expensive than the corresponding damage that could result from the impact of SLR. 2 This presentation will explore the options available to municipalities to take a proactive approach in protecting their critical water infrastructure from SLR. Options addressed will include conducting baseline risk assessments, impact studies, modeling, assessment and adaptation. THE EFFECTS OF SLR With the substantial impacts that SLR is projected to have over the next several decades, it is imperative that Florida s coastal communities adapt their critical infrastructure to mitigate potential impacts. Unfortunately, most communities have yet to begin incorporating SLR planning into their master planning process. A small change in sea level can make a big difference in the storm elevation experienced, similar to the last inch of water that overflows a tub. Throughout Florida, sea level is predicted to rise above the 1992 mean sea level as follows: SHORT TERM MID TERM LONG TERM to 10 inches to 26 inches to 61 inches These increases will almost certainly cause a tremendous amount of damage if steps aren t taken to harden infrastructure systems and make them resilient to SLR. Portions of cities and counties at or below the 4-foot hightide line will likely be underwater during the storm surge associated with today s 100-year storm. By 2050, storms of that magnitude are projected to occur five times as often due to the impact of SLR. In the United States, approximately five million people and 2.6 million homes are currently located below this 4-foot elevation. About 50% of this exposed population is located in Florida. In fact, 15 of Florida s 20 major population centers generating 79% of the state s total economy are located at or below this 4-foot elevation. In 2010, the estimated value of properties and associated infrastructure in these population centers had an approximate replacement value of $2 trillion. By 2030, the estimated replacement value is $3 trillion. Ibid Increased sea levels raise the launch pad for storms and high tides, causing more frequent and more intense storm levels, and this occurs well before mean sea levels permanently reach damaging heights. Some of the consequences associated with future SLR to critical water infrastructure are obvious; others are not. These consequences include, but are not limited to: Inundation of critical infrastructure including pump stations, lift stations and treatment plants. Increased frequency of flooding in vulnerable coastal areas, as well as interior areas, due to impairment of a region s stormwater infrastructure. Impairment can include flooded containment and treatment basins and/or impacts to gravity drainage or stormwater canals. It is estimated that in Florida, 6 inches of SLR would cripple up to half the stormwater management systems that have a tidally influenced outfall. Saltwater intrusion into freshwater aquifer and local supply wells. Rising sea level is and will continue to cause groundwater near the coast to become more saline, and will also cause groundwater elevations to increase. Increased saltwater infiltration and freshwater with increased groundwater table into wastewater collection systems where inflow and infiltration are already an issue during wet-weather periods. Contamination of areas outside the wastewater collection/ treatment system due to flooding/overflow. Contamination of freshwater supplies due to flooding of critical potable water infrastructure. The great majority of infrastructure in Florida was designed and constructed using historical data based on local mean sea level referencing National Geodetic Vertical Datum 1929 (NGVD29). This reference assumed a fixed, static mean sea level elevation and did not account for future SLR. 3 Therefore, much of the existing critical infrastructure of coastal Florida will need to be replaced or improved to accommodate an ongoing rise in mean sea level. An opportunity exists right now to relocate, harden, replace and adapt critical infrastructure to current and future conditions in ways that will avoid or mitigate at least to a manageable level potential impacts due to SLR. The entire community benefits from the responsible investment of critical water infrastructure adaptation to SLR by the respective utility. When done correctly, such investment will help water utilities experience minimal or no disruption during storm events. By accounting for the full costs of inundation risks, leaders can make realistic, MCKIM & CREED Protecting Critical Water Infrastructure from Sea Level Rise 2

3 strategic choices to be included in the utility s strategic plan, master plan, and capital improvement plan (CIP), resulting in maximum benefit and minimized risk. ANALYZING VULNERABILITIES TO MANAGE RISK To make their critical water infrastructure adaptable and climate-ready moving into the future, utilities should assess the vulnerability of their entire system as well as specific infrastructure. This planning exercise is really risk management, and is essential to avoiding loss of service, loss of asset value and, most importantly, risk to public health and safety. Questions that should be considered regarding system vulnerability include but are not limited to the following: How will SLR and increased storm surge affect my utility? What is the cost of not doing anything? What can be done to adapt the utility to SLR? What is the best adaptation strategy? How much will it cost to make the utility a climate-ready water utility? In choosing the value of infrastructure that should accommodate projected SLR, it is important to consider the following: What is the projected lifespan of the infrastructure? How difficult would it be to replace the infrastructure if necessary? How adaptable is the infrastructure? What are the interdependencies of this infrastructure with other infrastructure? What are the consequences of under-designing the RESEARCH RESULTS FOR: 5 SEA LEVEL RISE PREDICTIONS infrastructure? What is the benefit/cost analysis of the proposed action items? To determine the level of SLR that should be planned for, infrastructure can be divided into two categories: high-risk and low-risk. Critical, high-risk water infrastructure is defined as follows: Has a long projected life span (greater than 50 years), Is interdependent with other infrastructure or services, or Failure or contamination of the infrastructure could potentially have catastrophic results. The U.S. Army Corps of Engineers (USACE) has developed a web-based Sea Level Change Curve Calculator that, based on user input, calculates USACE sea level change scenarios. 4 For high-risk infrastructure, the upper range of the USACE SLR curve should be used during the conceptual design phase. Examples of these curves for two different regions can be seen in Exhibit #1. Low-risk infrastructure is defined as: Estimated Relative Sea Level Change Projections from Gauge: , Daytona Beach Shores, FL (2.32 mm/yr) Infrastructure expected to be constructed and then replaced within 10 years, Projects that are easily replaceable and adaptable, or Projects with limited interdependencies and limited consequences should the system fail. For this type of infrastructure, the lower projected SLR numbers could be considered reasonable to use in planning and conceptual design. 3 Exhibit 1 City of Daytona Beach City of Tampa DATE: USACE Sea Level Change Curve Calculator ( ) www. corppsclimate.us/ccaceslcurves.cfm USACE Low USACE Int USACE High USACE Calculator predicts the following: 2.32 mm/yr (Low USACE estimate) Year feet high sea level rise = ft BFE Year fee high sea level rise = ft BFE MCKIM & CREED Protecting Critical Water Infrastructure from Sea Level Rise 3

4 5 Estimated Relative Sea Level Change Projections from Gauge: , St. Petersburg, FL (2.36 mm/yr) USACE Low USACE Calculator predicts the following: 2.36 mm/yr (Low USACE estimate) Year feet high sea level rise = ft BFE USACE Int USACE High Year fee high sea level rise = ft BFE Evaluating Critical Water Infrastructure for SLR Adaptability By identifying the issues, exploring different adaptation strategies and understanding the benefits and costs of each strategy, utility leaders can make better-informed decisions that help achieve the utility s short- and long-term adaptability goals in a cost-effective manner. A practical, conservative approach for evaluating critical water approach for vulnerability to SLR and to make the infrastructure climate ready is as follows: UNDERSTAND THE BASELINE RISK. In completing this task, flood maps will be created to reflect the projected SLR impacts. These will be used to explore the exposure of critical water infrastructure to a range of water level increases resulting from high water level events such as storm surge and astronomical high tides combined with projected SLR. The maps can also serve as a valuable tool to illustrate what could happen if no action is taken. The following steps are completed as part of this task: Select appropriate local SLR scenarios. Identify a set of SLR curves that will be used for the analysis. NOAA has developed curves that can be used for coastal areas in Florida. Choose a few years along the planning horizon to be evaluated. Timeframes of interest will likely tie to the master planning horizon for your utility and the lifespan of the utility being evaluated. Develop high water level event scenarios. Based on SLR estimated, model storm surge for design storm based on the scenarios selected in step 1. Previous stormwater system modeling may be obsolete and may need to be re-evaluated as it relates to critical infrastructure. Assess vulnerable infrastructure for the no-action scenario. Based on the years and SLR curves to be evaluated, determine high tide and flooding limits for the design storm. Based on this assessment, determine critical water infrastructure that would be impacted if no action is taken. ASSESS WHAT CAN BE DONE DIFFERENTLY. Once the utility understands the severity of its baseline risks due to coastal flooding, the next step is to investigate how to adapt to these risks and become more resilient to flooding. SELECT ADAPTATION STRATEGIES TO FORM 1 ACTION SCENARIOS. An adaptation strategy is an individual measure, such as elevating or relocating a pump station, which reduces the impacts of flooding. An action scenario is a compilation of two or more of these strategies. Some factors that must be considered when developing adaptation strategies are as follows: The cost of strategies can vary significantly, depending on the unique characteristics of the utility and the community it services. MCKIM & CREED Protecting Critical Water Infrastructure from Sea Level Rise 4

5 Non-economic factors such as legal challenges or public outreach needs can increase the resources needed to implement a strategy. The lifespan and effectiveness of any project will depend on the severity of future events. 2 3 Based on the selected list of possible adaptation strategies, develop one or more action scenarios. Re-assess exposed infrastructure for each action scenario. Identify how each action scenario changes the respective coast flooding impacts. Determine how each action scenario impacts the level of flooding and its effect on critical infrastructure. Does the action scenario prevent flooding to a certain level? If so, note the water-level increases for which impacts are prevented and those for which impacts will be similar to the no-action scenario. Does the action scenario reduce the severity of flooding for a given water-level increase? If so, determine how much the level of flooding changes once the action scenario is implemented. Does the action scenario move infrastructure out of harm s way? If so, additional modeling over the no-action scenario will not be necessary. When dollar values are assigned to impacts, the difference in damage between the no-action and action scenarios will be defined as the avoided damage in this relocated infrastructure. Does the action scenario increase the resilience of the infrastructure? If so, the amount of damage to the infrastructure for a given level of flooding must be determined. This will not require additional flood modeling; however, the infrastructure raised or flood proofed needs to be included as part of the avoided costs estimate when evaluated. CALCULATE BENEFITS AND COSTS. Once the determination of exposure of infrastructure in terms of no-action and action scenarios is completed, a dollar value can be assigned to the impacts of present-day flooding as well as future flooding. 01 Create a list of primary, secondary and potential environmental impacts due to flooding using a matrix similar to the table on page 6. Source: What Will Adaptation Cost? An Economic Framework for Coastal Community Infrastructure June 2013 Eastern Research Group, Inc. Written under contract for the National Oceanic and Atmospheric Administration (NOAA). List potential impacts of implementation for each adaptation strategy identified in the action scenario. 02 List all impacts. Monetize Impacts The following questions should be answered when evaluating the value of impacts: What flood scenario is being addressed? How much damage will be done to the infrastructure under each scenario? How much is the infrastructure being evaluated worth? Create a table that lists the primary, secondary and environmental impacts that will be monetized for utility infrastructure. Create a table that lists the total benefits by water-level increase for each action scenario, similar to that shown in Table Estimate the costs of implementing the adaptation strategies The costs should include capital, engineering, legal, property, operation and maintenance for each adaptation strategy. Storm Type 2010 Damage * 2040 Damage * 2070 Damage * 2100 Damage * 1-year Residential: $75 Public Infrastructure: $20 SECONDARY DAMAGE Business Interruption: $5 Residential: $90 Public Infrastructure: $25 SECONDARY DAMAGE Business Interruption: $5 Residential: $120 Public Infrastructure: $22 SECONDARY DAMAGE Business Interruption: $8 Residential: $150 Public Infrastructure: $40 SECONDARY DAMAGE Business Interruption: $8 Table 2. Sample Table of Monetized Damage for the Risk Assessment. Source: What Will Adaptation Cost? An Economic Framework for Community Planners MCKIM & CREED Protecting Critical Water Infrastructure from Sea Level Rise 5

6 TABLE 1: POTENTIAL ENVIRONMENTAL IMPACTS DUE TO FLOODING 5 TOOL OR MEASUREMENT METHODOLOGY FEMA HAZUR MH FLOODING COAST OVERLAY INFRASTRUCTURE- LEVEL ECONOMIC DATA ON FLOOD-DEPTH DATA USE GENERAL ECONOMIC AND FLOOD DATA TO ESTIMATE NON-MARKET VALUATION METHODOLOGIES MONETIZ BUSINESS INTERRUPTED LOSS BENEFITS TRANSFER IMPACT PRIMARY IMPACTS Residential building damage* I I I I I Commercial building damage* I I I I I Damage to special facilities such as hazardous waste, wastewater treatment plants, landfills, and energy utilities* I I I I I Damage to essential facilities such as hospitals, fire stations and schools* I I I I I Vehicle damage I I I Building content loss* I I I I Road damage I I Bridge damage I Railway damage* I I Crop loss I I Loss of human life Animal and livestock loss I I SECONDARY IMPACTS Business interruption costs* I I I Debris cleanup I I Emergency response I I Evacuation costs I I School hours loss I I Rental income loss I I Relocation costs I I I Displaced families I I I Roadway congestion I I Anxiety and discomfort I I ENVIRONMENTAL IMPACTS Salinization of freshwater supply I I Parks, campgrounds, and beaches destroyed I I Wastewater intrusion I I Erosion I I Wetlands, mangroves, marshes, and estuaries destroyed I I Other ecosystem service-related costs I I MCKIM & CREED Protecting Critical Water Infrastructure from Sea Level Rise 6

7 SOUTH WATER TREATMENT PLANT Water- Level Increase No- Damage #1 Damage #1 Other Monetized Benefits #1 Other Costs 3 feet feet 1, #1 Total Monetized Benefits 12 feet 4, , feet 16, ,020 Table 3. Sample table of Monetized Damage for the Risk Assessment. Source: What Will Adaptation Cost? An Economic Framework for Community Planners Make a decision. Using the monetized, quantitative and qualitative data, determine which action scenario(s) provide the best value for the available monies. This decision will normally be based on benefit/cost analysis, financial feasibility, and other relevant considerations such as public relations, legal, political, etc. 1 2 Calculate the capital and operation and maintenance costs for each action scenario. Create a table that compares benefits to costs, such as in Table 4. Rank the action scenarios from best to worst, based on the outlined process. flooding. Non-monetized benefits in this case, the nonmonetized benefits for action scenario #3 are ranked higher but #3 has a lower benefit/cost ratio than #1. This part of the analysis must include some subjectivity as well as the objectivity of the benefit/cost analysis. A utility must make sure that funding of the action scenario is feasible, along with carrying the O&M costs. Case Studies PRELIMINARY EVALUATION BETHUNE POINT WWTP, CITY OF DAYTONA BEACH The City of Daytona Beach s Bethune Point Wastewater Treatment Plant (WWTP) sits along the tidally influenced Halifax River. The 20-mgd WWTP has many decades of planned service remaining. Using the USACE high curve for this critical infrastructure (Exhibit 1), which is suitable for the evaluation of Bethune, it is understood that mean sea level will rise by approximately 0.83 feet by 2030 and approximately 2.23 feet by The corresponding design 100-year storm-surge elevation indicates an additional 4 feet on top of the mean sea level rise by 2030 and 5 feet by Exhibit 2 shows estimates, in 1-foot elevation increments, of storm-surge elevation from 1 foot through 5 feet. From the preliminary evaluation, it can be seen that a 100- year storm surge in 2030 will inundate the plant. Under this scenario, access to the site will be difficult if not impossible due to storm surge, and structures, pumping stations and generators will be flooded. As mean sea level elevation continues to rise over time, the frequency and intensity of flooding will only increase. SOUTH WATER TREATMENT PLANT-3 FEET 2030 Total Monetized Benefit Total Costs (NPV) Net Benefits Benefit to Cost Ratio Non Monetized Benefits # Medium # Low # High Table 4: Comparison of Benefits to Costs. Based on the evaluation above, action scenario #1 would appear to be the recommended action scenario for 3 feet of Exhibit 2. Bethune Point WWTP Sea Level Rise Incremental RECOMMENDATION For the Bethune Point WWTP, the baseline risk is understood. Based on this preliminary evaluation, it is recommended that a study be completed for this facility. The study would look at MCKIM & CREED Protecting Critical Water Infrastructure from Sea Level Rise 7

8 specific design storm-surge events during the lifespan of the facility. Evaluations of different adaptation strategies to make the infrastructure climate resilient would be prepared, and may include such options as: Relocate components associated with the plant to get them above future design storm-surge elevation. Floodproofing the facility through the use of dikes, berms and/or pumping systems. Building natural buffer zones. Flood-proofing/hardening critical infrastructure on site. Diverting flow to a facility out of harm s way and abandon existing facility. Following a benefit/cost analysis that considers both monetized and non-monetized benefits and costs, a plan consisting of action scenarios can be adopted. The action scenarios can then be integrated into the utility s CIP for implementation. This allows the utility to address in a timely manner both financial realities as well as the everincreasing storm-surge/flooding threat due to SLR. Done correctly, this process will help adapt critical water structure to be resilient to a level deemed acceptable to its decision makers to the threats of flooding from increased sea level. PRELIMINARY EVALUATION CURREN AWTP, CITY OF TAMPA The City of Tampa s Curren Advanced Water Treatment Plant (AWTP) is located in the Port of Tampa on Hillsborough Bay. The Curren AWTP has a capacity of 96 mgd, and there are no plans on the horizon to relocate or to send flows elsewhere. Using the USACE high curve for the Curren AWTP (Exhibit 1), which is suitable for the evaluation of Curren, it is understood that mean sea level will rise by approximately.83 feet by 2030 and approximately 2.24 feet by The corresponding design 100-year storm-surge elevation corresponds to 4 feet on top of the mean sea level rise by 2030 and 5 feet by Exhibit 3 details 1-foot elevation increments for storm-surge elevation from 1 foot through 5 feet. From the preliminary evaluation it can be seen that for a 100-year storm surge in 2060, the plant will remain free of flooding. There will be some flooding of access roads to and from the site that should be evaluated, but the plant and corresponding infrastructure appear to be at a high enough elevation to sustain the design storm surge even with projected sea level rise as far out as RECOMMENDATION Based on the preliminary evaluation, it is recommended that a study be completed to examine access to the plant. Location and elevation of lift stations feeding the plant should also be examined to determine their vulnerability to the future design storm-surge elevation. Conclusion Changes in climate threaten to disrupt critical water utilities within the coastal regions they serve. The most immediate threat will be from storm surge as sea level rises. It is estimated that a 6-inch rise in mean sea level will cause up to 50% of coastal storm water systems to be rendered ineffective. It is estimated that investing $50 billion in adaptation strategies (risk management/ management strategies) over the next 20 years could lead to approximately $135 billion in averted losses over the lifetime of adaptive measure. 1 Many utility managers in coastal regions are increasingly aware of their facilities vulnerability to SLR and the increased frequency and intensity of flooding and storm surge associated with that rise. Completing a preliminary assessment of critical water infrastructure vulnerability is a reasonable first step in assessing a utility s preparedness to meet future SLR and its resilience to storm surge and flooding. Although many utilities cite economic uncertainties as reason for inaction, the assessment is relatively inexpensive. In fact, studies indicate that the costs of inaction are four- to 10-times greater than the costs of investing in hazard mitigation. 7 Investments by the utility in climate change adaptation projects offer win-win opportunities for coastal communities. The projects should also yield positive financial returns on investments, create jobs, stimulate local economies and can revitalize the health of ecosystems. 8 Exhibit 3.Curren WWTP Sea Level Rise Incremental MCKIM & CREED Protecting Critical Water Infrastructure from Sea Level Rise 8

9 Sources: 1. Unified Sea Level Rise Projection Southeast Florida; Southeast Florida Regional Compact Climate Change, October Climate Central. April Florida and the Surging Sea: A Vulnerability Assessment with Projections for Sea Level Rise and Coastal Flood Risk. 3. What Will Adaptation Cost? An Economic Framework for Coastal Community Infrastructure June 2013 Eastern Research Group, Inc. Written under contract for the National Oceanic and Atmospheric Administration (NOAA). 4. Sea Level Change Curve Calculator ( ), User Manual (Draft), Manual_2014_88.pdf. 5. What Will Adaptation Cost? An Economic Framework for Coastal Community Infrastructure June 2013 Eastern Research Group, Inc. Written under contract for the National Oceanic and Atmospheric Administration (NOAA). 6. Florida and the Rising Sea Climate Central/Surging Seas; Dr. Ben Strauss; October Coast Zone Development and Ecosystems in the United States: The Third National Climate Assessment. J.M. Melillo-U.S. Global Change Research Program The Economic Case for Restoring Coastal Ecosystems. Center for American Progress and Oxfam America. M.J. Buchanan The Florida Oceans and Coastal Council, Tallahassee, Florida, December Climate Change and Sea-Level Rise in Florida: An Update on the Effects of Climate Change on Florida s Ocean & Coastal Resources. MCKIM & CREED Protecting Critical Water Infrastructure from Sea Level Rise 9