Addressing Sea Level Rise in 2019/2020 Shoreline Master Plan Updates: Moving Beyond Base Flood Elevation. Jim Simmonds August 2, 2018

Transcription

1 Addressing Sea Level Rise in 2019/2020 Shoreline Master Plan Updates: Moving Beyond Base Flood Elevation Jim Simmonds August 2, 2018

2 Climate change is one of the paramount challenges for our generation and generations to come. Health Safety Economy Environment

3 King County s 2015 Strategic Climate Action Plan A 5-year blueprint for climate action.

4

5 Priority action #12: Plan for sea level rise impacts on coastal zones The Water and Land Resources Division will prepare a comprehensive strategy to reduce risks to Puget Sound shoreline homes and businesses at increasing risk of flooding and coastal erosion due to sea level rise.

6 King County experiences coastal flooding. Dockton Road along Tramp Harbor on Vashon Island North end of Vashon Island near ferry dock

7 Vashon-Maury Island has 699 structures in the coastal 100-year floodplain. There are more structures in the floodplain in the cities on the mainland.

8 King County has coastal landslide risks From Geoengineers 2015

9 The work plan for developing a comprehensive sea level rise strategy includes four main activities. Understand Current Projections Update KC Policies and Codes for Shoreline Development Address King Countyowned assets Coordinate with Partners to Standardize Approach

10 King County has three different authorities that apply to the marine shoreline King County is the local land-use authority in unincorporated areas. King County has public health authority for onsite sewage systems and drinking water supplies for the entire county. King County implements certain floodplain management and flood risk reduction authorities for the entire county via agreement with the King County Flood Control District.

11 Adaptation actions to date Remapped coastal floodplains. Raised base elevation for new construction to three feet above the 100-yr flood elevation. Consider sea level rise in public infrastructure projects. Consider sea level rise in shoreline restoration projects. Notify developers about sea level rise. Encourage project developers to consider sea level rise.

12 Form crossdepartmental team. Review shoreline policies and codes. Approach for reviewing codes and policies Identify ideas for addressing sea level rise. We are here. Assess all ideas. Make recommendations to department managers.

13 The cross-department team includes a wide variety of expertise. Permitting. Land use policy. Public health. Stormwater management. Floodplain management. Hydrogeology. Shoreline ecology. Conservation. Climate preparedness.

14

15 Ideas Getting Assessed 1. Strengthen requirements for coastal 100-year floodplain Prohibit new groundwater wells. Prohibit new on-site septic systems. Prohibit new structures and substantial improvements in the coastal velocity exclusion (VE) zone.

16 CRITICAL

17 Ideas Getting Assessed 2. Create a new critical area called Sea Level Rise Hazard Zone and set requirements within this new zone Extends up and in from coastal 100-year floodplain. 3-feet higher than 100-yr flood elevation. Incorporate restrictions to prevent future flood damage. Raise floor elevations. Waterproof on-site sewage systems. Extend groundwater well casings vertically.

18

19 Ideas Getting Assessed 3. Commit to updating maps and data Update coastal floodplain maps every 20 years or when sea level has risen one foot, whichever is earlier. Update Sea Level Rise Hazard Zone maps. Update shoreline habitat maps of drift cells, spawning areas, eelgrass beds, etc. Track insurance claims, numbers of structures, elevations, setbacks, bulkheads, etc.

20

21 Ideas Getting Assessed 4. Strengthen setback requirements on top of steep slopes Establish 75 feet as the standard setback on top of steep slopes for new construction. Allow for 50-foot setback if geotechnical report demonstrates 50 years of erosion potential. Require geotechnical reports to account for increased erosion and landslide rates due to sea level rise.

22

23 Ideas Getting Assessed 5. Strengthen bulkhead requirements for developed parcels Increase toe of bulkhead elevation requirement to three feet above the Mean Higher High Water elevation level. If not feasible, require structure to be elevated to 3 feet above the 100-year floodplain elevation OR moved back to allow for 50 years of erosion so bulkhead is not needed. If elevating or moving structure is not feasible, then allow toe of bulkhead to be as low as the Mean Higher High Water elevation.

24

25 Ideas Getting Assessed 6. Help shoreline residents adapt to sea level rise Expand conservation efforts to also purchase properties from willing sellers who face high flooding and landslide risks. Provide financial assistance to help property owners elevate or move structures. Educate property owners about sea level rise, legal requirements, and possible preparedness actions.

26

27 To complete by October Finish assessing all of the ideas. Develop staff recommendations and send to department managers. Select changes to implement.

28 Leverage planned processes 2019 update to shoreline code. 2019/2020 update to Board of Health code update to Flood Hazard Management Plan update to the Stormwater Design Manual. Annual updates to Comprehensive Plan. Ongoing improvements to internal processes.

29 Questions? Jim Simmonds Water Quality and Quantity Unit Supervisor