Policies for a Rising Bay Project Steering Committee Meeting #3 - - PowerPoint PPT Presentation

▶
policies for a rising bay
SMART_READER_LITE
LIVE PREVIEW

Policies for a Rising Bay Project Steering Committee Meeting #3 - - PowerPoint PPT Presentation

Nov 19, 2023 128 likes •422 views

The Policies for a Rising Bay Project Steering Committee Meeting #3 January 22, 2016 Overview Brief Presentation of Case Studies Developed in collaboration with subcommittee Case studies are hypothetical Brief Presentation of Policy

slide-1
SLIDE 1

The

Policies for a Rising Bay

Project

Steering Committee Meeting #3 January 22, 2016

slide-2
SLIDE 2

Overview

  • Brief Presentation of Case Studies

– Developed in collaboration with subcommittee – Case studies are hypothetical

  • Brief Presentation of Policy Analysis

– Incorporates feedback from subcommittee meetings – Highlights key policy issues

  • Discussion
slide-3
SLIDE 3

The

Policies for a Rising Bay

Project

Transportation Case Study

Miriam Torres Erik Buehmann

slide-4
SLIDE 4

Gr Ground T

  • und Transportation

ransportation

  • Purpose: maintain

ground transportation, shoreline habitat and recreation resources, and protect the surrounding community from future flooding

slide-5
SLIDE 5

Lid + Mudflat Recharge & Beach

  • Seawall and Lid:

– 30 feet high wall with a park and public access – Bay trail is relocated to the top of the lid – Protection: 100-year BFE + 5.5 feet of SLR

  • Mudflat Recharge & Beach:

– Initial placement: 98 acres of sediment over 13,000 linear feet – Sediment tapering linearly for about 400 feet into the Bay – Wave attenuation, recreational, and habitat benefits

slide-6
SLIDE 6

Current Conditions & SLR

slide-7
SLIDE 7

Mudflat Recharge, Beach, Lid

Bay Fill = 98 acres over 13,000 linear feet / 647,443 cubic yards (cy) Shoreline Band Fill = 21 acres / 315,519 cy of sediment / 31,551 cy of groins

slide-8
SLIDE 8

Impacts

Seawall:

  • Erosion of offshore mudflats
  • Potential shoreline erosion
  • Bay views
  • Public access

Mudflat Recharge + Beach:

  • Habitat loss and gain
  • Siltation
slide-9
SLIDE 9

Case Study Analysis

  • Minimum Fill
  • Benefits and Detriments
  • Mitigation
slide-10
SLIDE 10

Policy Issues

  • Minimum fill issues

– Long-term impacts of beach recharge – Potential habitat benefits and impacts – Alternatives that could provide benefits with less fill

slide-11
SLIDE 11

Policy Issues

Photo: SF Chronicle

  • Public Benefits and Public Detriments

– Flood protection

  • Highway
  • Community

– Increased public access – Habitat loss – Loss of open water area

slide-12
SLIDE 12

Policy Issues

  • Mitigation

– Substantial amount of fill = substantial mitigation – Fee-based mitigation unlikely – Supplemental mitigation for beach replenishment

slide-13
SLIDE 13

Discussion

slide-14
SLIDE 14

Questions

  • How to encourage innovative sea level

rise approaches and minimize the potential of failure?

  • How to weigh long-term potential public

benefits over short-term impacts?

  • How should mitigation be evaluated for

sea level rise adaptation projects?

slide-15
SLIDE 15

The

Policies for a Rising Bay

Project

Shoreline Community Case Study

Miriam Torres Brenda Goeden

slide-16
SLIDE 16

Shor Shoreline Community eline Community

  • Purpose: flood

protection along the creek and Bay front, prepare marsh for a rising Bay.

slide-17
SLIDE 17

Tide Gate

Tide Gate:

– Concrete structure with gated culverts – Top of the gate at

  • 11ft. NAVD88

– Protection: 3 feet of SLR above MHHW (with 2 ft. of freeboard)

slide-18
SLIDE 18

Horizontal Levee & Sediment Augmentation

Proposal:

  • Flood protection
  • Build levee to 16’ NAVD88 with a 30:1 slope
  • Protection: 3 feet of SLR
  • Provide transition habitat
  • Reuse finer grained dredged sediment from creek

to raise grades of the marsh

slide-19
SLIDE 19

Horizontal Levee

Bay Fill = 69 acres over 10,000 linear feet / 555,555 cubic yards

slide-20
SLIDE 20

Potential Impacts

Tide Gate:

  • Hydrology
  • Habitat & Wildlife
  • Sediment transport

Horizontal Levee:

  • Habitat
  • Wildlife
  • Public access
slide-21
SLIDE 21

Applicable BCDC Laws & Policies

  • McAteer Petris Act Sections 66601, 66605, and 66632*
  • Relevant San Francisco Bay Plan Policies*
  • Fish, Other Aquatic Organisms and Wildlife (1, 2, & 4)
  • Water Quality (1, & 2)
  • Water Surface Area and Volume (1, 2 & 3)
  • Tidal Marsh and Tidal Flats (1, 2, 3, 5, 6 & 8)
  • Climate Change (1, 2, 3, 5 & 7)
  • Safety of Fill (1, 2, & 4)
  • Shoreline Protection (1, 3, 4, & 5)
  • Dredging (2, 3, 4, & 11)
  • Public Access (1, 2, 5)
  • Appearance, Design and Scenic Views (2)
  • Fill in Accord with the Bay Plan (1)
  • Mitigation (All)
slide-22
SLIDE 22

Tide Gate

  • Protects existing development from

flooding

  • Policies that protect species, habitat and

physical processes and impacts

  • Near term flood protection benefits vs.

long-term strategy

  • Mitigation
slide-23
SLIDE 23

Horizontal Levee

  • Protects community and provides

transitional habitat

  • Impacts to healthy marsh and policies
  • Expected time lag in habitat development
  • Mitigation may be required
slide-24
SLIDE 24

Sediment Augmentation

  • Beneficial reuse of sediment
  • Temporal loss of habitat within creek
  • Marsh plain elevation capital
  • Potentially self-mitigating
slide-25
SLIDE 25
  • Policy consistency depends on details of

the project

  • More information is necessary
  • Short-term vs. long-term impacts and

benefits

  • Public detriments and benefits apply to the

region Other Considerations

slide-26
SLIDE 26

Discussion

slide-27
SLIDE 27

Questions

  • How to evaluate tide gate impacts to

long-term land use decisions and natural processes?

  • How to weigh long-term potential public

benefits over short-term impacts?

  • How should mitigation be evaluated for

sea level rise adaptation projects?