1. Climate Change Threat Floods

2. Potential Flooding Impacts How might our community be impacted by floods? 2

3. Flooding Impacts Utility Infrastructure Damage 3

4. Adaptation Options for Utility Infrastructure Damage Establish regional interconnections so that you have an alternate supply of water in the event of infrastructure damage and service interruption Establish alternative power supplies to support operations in the event of power loss Monitor and inspect the integrity of existing infrastructure Elevate or flood-proof assets using barriers (examples include berms, dikes and retractable gates) Join a mutual aid network, such as WARN (Water and Wastewater Agency Response Network) 4

5. Extreme Event Example: Extreme Precipitation in Warwick, Rhode Island Utility Infrastructure Damage Record-breaking rainfall along Pawtuxet River in Warwick, RI in March 2010 Major flooding in the area, worst damage seen in 200 years The Warwick Wastewater Treatment Plant and six pump stations were completely flooded Equipment was moved to higher ground and portable pump stations were purchased 5

6. Extreme Event Example (cont’d): Extreme Precipitation in Warwick, Rhode Island 6

7. Flooding Impacts: Increased Runoff 7

8. Adaptation Options for Increased Runoff Implement green infrastructure to capture stormwater Invest in watershed management Model potential stormwater flows to understand probable impacts to your service area Monitor runoff, vegetation and land use changes and incorporate data into models 8

9. Flooding Impacts: Stressed Sewer Systems 9

10. Adaptation Options for Stressed Sewer Systems Implement green infrastructure in the service area to capture runoff Acquire and manage existing ecosystems Reduce infiltration and inflow by inspecting existing sewer mains and repairing and replacing, if necessary Increase capacity or capabilities of wastewater treatment system and facilities Model potential stormwater flows to understand potential impacts to your service area 10

11. Adapting to Stressed Sewer Systems Example: Chicago, IL Chicago has a combined sanitary and stormwater sewer system System experiences combined sewer overflows (CSOs) with intense rainfall events CSOs degrade water quality in the Chicago River and Lake Michigan City launched a green infrastructure initiative to implement measures including green roofs, tree canopies along city streets and bio-retention areas for new development 11

12. Flooding Impacts: Reduced Water Quality Sediment and Nutrient Loading 12

13. Extreme Event Example: Hurricane Irene, Mid-Atlantic and New England Impacts Sediment and Nutrient Loading Hurricane Irene inflicted widespread damage to public and private infrastructure in August 2011 Floodwaters inundated and overwhelmed many water and wastewater facilities, including distribution and collection systems Floodwaters along the main branch of the Pemigewasset River in New Hampshire carried over 59 million tons of sediment River flooding records were broken on 26 rivers in New York (14), New Jersey (8) and Vermont (4) 13

14. Extreme Event Example: Hurricane Irene, Mid-Atlantic and New England Impacts 14

15. Adaptation Options for Sediment and Nutrient Loading Acquire and manage ecosystems Alter treatment techniques to be more adaptive to changes in water quality Construct flood barriers to protect water quality from potential changes in sediment and nutrient loads Monitor water quality in source waters 15

16. Adapting to Increased Sediment and Pollutant Loading Example: Denver, CO Post-wildfire flash floods washed 1 million cubic yards of sediment into the Reservoir, creating operational challenges and water quality issues Sediment removal project at Strontia Springs in 2010 (over 625,000 cubic yards excavated) Denver Water has spent more than $26 million on water quality treatment, sediment and debris removal, reclamation techniques and infrastructure improvement projects 16

17. Flooding Impacts: Sea-Level Rise and Storm Surge 17

18. Extreme Event Example: Storm Surge in Louisiana Saltwater Intrusion Coastal aquifers are vulnerable to saltwater intrusion due to storm surge and sea-level rise St. Tammany Parish is located on the northern shore of Lake Pontchartrain in Louisiana The Parish uses a sole-source aquifer system which supplies the majority of its freshwater After coastal storm surges from Hurricanes Katrina and Rita, saltwater intrusion was found in portions of the shallow aquifer 18

19. Extreme Event Example: Storm Surge in Louisiana (cont’d) 19

20. Adaptation Options for Coastal Storm Surge and Sea-Level Rise Construct flood barriers – temporary or hard (sea walls, dikes or levees) to protect critical infrastructure Protect, acquire or manage ecosystems that can be cost-effective measures for flood control and water quality management Monitor saltwater intrusion into aquifers and estuaries Perform modeling of sea-level rise and storm surge Obtain adequate flood insurance coverage 20

21. Adapting to Sea-Level Rise Example: Massachusetts Water Resources Authority (MWRA) Sea-level rise would necessitate construction of a sea wall around the wastewater treatment plant proposed on Deer Island Engineers incorporated sea-level rise into the design plan Wastewater treatment plant was constructed 1.9 feet higher than it would otherwise have been built Eliminated the need to pump effluent over a seawall Sea-level rise considerations are currently built into adaptation planning, facility designs, rehabilitation projects and greenhouse gas mitigation projects 21

22. Extreme Event Example: Storm Surge on North Carolina Coast Coastal Flooding Severe coastal flooding between Cape Hatteras and Oregon Inlet, NC was triggered by Hurricane Irene in August 2011 Storm surge was approximately 6.5 feet high on the sound- side Resulting impacts to the coast included dune erosion, over- wash, and in some areas, dune retreat The combination of coastal storm surge, waves, and high winds were deadly In the U.S., the Atlantic and Gulf coastlines are densely populated, and many regions lie in areas that are less than a few meters above sea-level 22

23. Extreme Event Example: Storm Surge on North Carolina Coast (cont’d) 23

24. Adapting to Coastal Storm Surge Example: Planning in New York City Storm surge from Hurricane Sandy in 2012 damaged infrastructure, caused beach erosion and flooding Coastal protection plan was developed to protect assets Measures under consideration: Beach nourishment Wetland restoration Seawalls Tide gates Storm surge barriers or levees 24

25. Community and Economic Impacts Service disruptions can cause customers to lose confidence in their utility’s ability to provide clean and safe water to customers Local businesses suffer and may lose revenue if they lack reliable access to water or sewer services What can be done? Collaborate with other community partners to develop more sustainable community and regional plans Discuss adaptation options with local businesses Work with local governments to communicate adaptation activities to customers 25