Del Mar City Council
June 6, 2022

Del Mar City Council Meeting Agenda
Del Mar City Hall
1050 Camino del Mar, Del Mar, California
June 6, 2022 City Council Meeting

INFORMATION RECEIVED

AFTER THE COUNCIL AGENDA

WAS DISTRIBUTED
(“Red Dots”)
1 Sarah Krietor
From: Payson Stevens <[email protected]>
Sent: Friday, June 3, 2022 3:15 PM
To: Dwight Worden; Terry Gaasterland; David Druker; Tracy Martinez; Dan Quirk; Ashley Jones; City Clerk Mail Box
Cc: Weiss, Shirli; Laura Schaefer Biz; Al Tarkington; Drew Cady; Camilla Rang; John Stahl; Karen Lare; Weare, John; Tom Grindle
Subject: Fwd: Letter of Concern/Opposition to Del Mar SANDAG Seawalls for June, 8 2022 Agenda item Wednesday 7b - CC-0005-21
Attachments: Del Mar Beach Coastal Comm-Payson Stevens 3 June 2022.pdf; DEL MAR BLUFFS IMPACTS-Viz n Science Report 8Nov2021.pdf; DEL MAR BLUFFS IMPACTS-Science Report 8Nov2021-Overview.pdf; Young_etal_2010_JCR.pdf; Young_etal_2009 _Geomorph.pdf; Young_2018.pdf; As California Cliffs Erode, UC San Diego Team Works to Track and Understand these Changes.pdf
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To the Del Mar City Council:

I copied you on my opposition/concern just sent email and letter to the Coastal Commission for their upcoming June, 8 2022 Agenda item Wednesday 7b - CC-0005- 21 meeting in Del Mar
I am forwarding it to you directly as I wish to have my letter in the Del Mar public record (Red Dot) for the upcoming Del Mar Council meeting this Monday June 6, 2022.

It would be an abrogation of the Council's duty to our community to allow the 1.5 miles of SANDAG proposed seawalls with the Coastal Commission's Conditional Concurrence.

You've heard our consistent voices for many months now, in this challenging battle of the train and tracks on the Del Mar Bluffs, with fencing and cliff engineering proposals. The proposed SANDAG seawalls are yet another outrageous assault on our beaches, which is not supported by any respected scientific research on seawall impacts on beach erosion, any Environmental Impact Report, nor the majority of the community's opposition.

June 6, 2022 Item 13
2 SANDAG is proposing to eliminate 49,566 square feet of beach area that would otherwise be available to the public for coastal access and recreation...and for thirty years! This is totally unacceptable.

Many of us would rather see bluff pilings (to the engineering proper depth), especially as many already exist at the Bluff top. They do not impede nor impact access to the beaches below nor the uglification of our beach-bluff landscape.

I trust and encourage the Council to vote together in one united voice to oppose SANDAG's, and now unfortunately, the Coastal Commission, egregious move against one of the defining aspects of Del Mar's beauty and character.

There are alternatives that we all must fight for at all levels of opposition.

One united voice for one preserved, natural Del Mar beach.

This is your legacy work that will affect the next 1-2 generations of young people.

Thank you.

Sincerely yours,
Payson R. Stevens
---------- Forwarded message ---------
From: Payson Stevens <[email protected]>
Date: Fri, Jun 3, 2022 at 2:47 PM
Subject: Letter of Concern/Opposition to Del Mar SANDAG Seawalls for June, 8 2022 Agenda item Wednesday 7b - CC0005-21 To: <[email protected]>, <[email protected]>, <[email protected]>, <[email protected]>, <[email protected]>, <[email protected]>, <[email protected]>, <[email protected]>, <[email protected]>, <Effie.Turnbull[email protected]>, <[email protected]>, <[email protected]> Cc: <[email protected]>, <[email protected]>, <[email protected]>, Leslie, Kanani@Coastal <[email protected]>, <[email protected]>, <[email protected]>, Dwight Worden <[email protected]>, Terry Gaasterland <[email protected]>, David Druker <[email protected]>, Tracy Martinez <[email protected]>, Dan Quirk <[email protected]>, Ashley Jones June 6, 2022 Item 13
3 <[email protected]>, Weiss, Shirli <[email protected]>, Al Tarkington <[email protected]>, John Stahl <[email protected]>, Laura Schaefer Biz <[email protected]>, Camilla Rang <[email protected]> Respected Coastal Commissioners & Staff:

Attached find my letter of Concern and Opposition for the upcoming:

Public Comment on June, 8 2022 Agenda item Wednesday 7b - CC-0005-21 (SANDAG, San Diego Co)
In addition to my letter please find the following support attachments:
• Impacts of Proposed NCTD and SANDAG Engineering on the Del Mar Bluffs & Beach - - Scientific Questions and Concerns: Request for Coastal Commission Action - submitted to Commission on November 8, 2021
• Overview Summary for Science Report
• Adam Young, Scripps Institution of Oceanography: three research papers on Southern California coastal processes1
• UCSD News: As California Cliffs Erode, UC San Diego Team Works to Track and Understand these Changes May 26, 2022
Thank you for your attention to my and the Del Mar community concerns.

Sincerely yours,
Payson R. Stevens
CCC Staff: Please confirm receipt of this email.
--
Payson R. Stevens
www.paysonrstevens.com
Artwork & Paintings
VideoTonePoems III DVD
VideoTonePoems II DVD
VideoTonePoems I DVD
Indian National Park/Friends of GHNP
The World In You
You In The World
Meshuggenary
June 6, 2022 Item 13
1 Payson R. Stevens: Public Comment for June 8, 2022 Agenda item Wednesday 7b – June 3, 2022 To [email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
From: Payson R. Stevens
Re: Public Comment on June 8, 2022 Agenda item Wednesday 7b - CC-0005-21 (SANDAG, San Diego Co)
Date: June 3, 2022
Respected California Coastal Commissioners & Staff:

I am a scientist, who studied at Scripps Institution of Oceanography, and consultant whose clients included NOAA, NASA and the US Geological Survey.

I am also the co-author (with Terry Gaasterland) of the Report: Impacts of Proposed NCTD and SANDAG Engineering on the Del Mar Bluffs & Beach -- Scientific Questions and Concerns:

Request for Coastal Commission Action, which was sent to the Commission on November 8, 2021.

I am attaching it again for your review along with the Report’s Overview Summary -- please scan this first as it has 3-D Google Earth visualizations showing the impacts of seawalls. If you and Staff read our report again, you will see there are many unanswered scientific, coastal processes dynamics, and geology questions that remain unanswered or even considered as critical to the Commission’s responsibility and mandate.

I am writing to all of you to express my concern at your Report and Consistency Certification No. CC-0005-21. That the Coastal Commission staff’s recommendation would be to grant Conditional Concurrence to San Diego Association of Governments (SANDAG) is very troubling.

June 6, 2022 Item 13
2 Payson R. Stevens: Public Comment for June 8, 2022 Agenda item Wednesday 7b – June 3, 2022 The bottom line of the beach impacts of your concurrence would be:
• Del Mar’s south bluffs will have 1.5 miles of 10-foot seawalls at 15th south to 11th, 9th south to 6th Streets, and 4th south to Anderson canyon. • The Commission’s “condition” for approval is for the seawalls to be in place for 30 years.

So, the Commission is approving 1.5 miles of 10-foot high seawalls to be in place until 2053 (30 years from next year).

How is it possible for the Commission to consider the devastating impacts of SANDAGs proposal and concur with them? Your legal mandate is to protect the beaches and bluffs of California coastal region as stated in your Mission:
(https://www.coastal.ca.gov/whoweare.html):

Protecting & Enhancing California's Coast
Studies by scientists at Scripps Institution of Oceanography (SIO) clearly understand basic coastal science and show that seawalls can change wave dynamics at the cliff base. If the cliff is not vertical, the waves can runup on to the cliff and dissipate wave energy. If a seawall is put in a location like this, the waves will reflect of the wall instead. This could cause what is termed as "active beach erosion". Reflective waves could also impact surfing conditions during high tides.

Without the necessary Environmental Impact Report (EIR), which is another mandate of the Commission, we don’t know how significant these impacts could be.

Has the Commission even considered:
• The impacts of sea level rise/global warming/climate change, which is already underway? • Ensuring that our sandy beaches will not be eroded or scoured away? • Seawalls affecting/destroying many community benefits, not to mention sand-replenishment costs? Benefits that the beaches confer to Del Mar and the wider community of visitors? • Other alternatives based on input from impartial engineering experts? Are these not part of your responsibility along with the proper procedures for an EIR? Are not the concerns of 3,300 citizens who have signed the Petition to the Coastal Commission, asking these important questions being addressed with their on-line appeal? The Commission certainly must not support/approve the additional hardening of our coastline and preventing/removing public access. As your CC-0005-21 (SANDAG) Report states: the proposed project seawalls would occupy 49,566 square feet of beach area that would otherwise be available to the public for coastal access and recreation.

There are other options. One is to put in pilings, at the proper depth, to help hold the cliff substratum. There are already many that have been placed at the Bluff top. More can be added, or the existing ones strengthened. And trains moving along the Bluff must be slowed down to minimize vibrations and further Bluff destabilization/collapse.

June 6, 2022 Item 13
3 Payson R. Stevens: Public Comment for June 8, 2022 Agenda item Wednesday 7b – June 3, 2022 Yes, they would be permanent, but they would also hopefully confer bluff stability and not destroy the beaches, their access, and their natural beauty (with high, ugly seawalls).

Yes, these are complicated issues when important infrastructure is involved. We have all known for many decades that the train tracks and rail movement are unstainable, and they must be removed. But the funds are not immediately forthcoming. And until then, unfortunately, these issues will only become more common as sea level rises.

SIO and UCSD are at the forefront of studying Del Mar Bluff and beach coastal processes, especially with new monitoring technology such as LIDAR (see attached article, As California Cliffs Erode, UC San Diego Team Works to Track and Understand these Changes). The Commission must include their expertise as part of the EIR along with other recognized California coastal scientist experts.

There is a much larger issue that the Commission is facing with approval of SANDAG’s Conditional Concurrence:

You will be setting a dangerous legal precedent for the entire California Coastline that other interests will have the ability to challenge any legal or community concerns and opposition to projects that impact our coasts. Thus, you will be undermining the Coastal Commission’s legal and environmental protection authority! I sincerely hope and trust that you will fulfill your mandate for all Californians--and our coasts-- with measured alternatives to the SANDAG proposed seawalls, based on sound scientific and all appropriately mandated and unbiased environmental assessments.

Commissioners, please understand and respect the science, listen to the community, and protect our beaches and their access. This will be your legacy.

Thank you.

Sincerely yours,
Payson R. Stevens
50-year Del Mar homeowner/resident
Please confirm receipt of this email and attachments.

June 6, 2022 Item 13

Proposed NCTD and SANDAG Engineering
Impacts on the Del Mar Bluffs & Beach
Scientific Questions and Concerns
June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 2 EXECUTIVE SUMMARY
THE PROBLEM
• The San Diego Association of Governments (SANDAG) and North County Transit District (NCTD) have sweeping engineering projects underway and in planning that will forever destroy the entire 1.7 mile Del Mar Coastal Bluff and beaches below. • The SANDAG/NCTD plans are projected to reinforce railroad tracks on top of the Bluff for 20-30 years in the face of inevitable bluff collapse within this timeframe due to sea level rise. • Without objective, independent review, the SANDAG/NCTD plans will impose environmentally destructive structures on the Bluff’s top, face, and toe, and will bury the beaches below. • For 20 years, local governments have postponed and ignored the necessary relocation of the railway off the fragile Bluff. This cannot continue.
• The railway must be relocated within 7 to 10 years to avoid further engineering expense and environmental destruction.

IMPACTS (see page 5 and Appendix A)
• The natural Bluff will be destroyed and replaced by engineering. • Beaches will be buried behind continuous seawalls.
• Public views and beach experience will be ruined.
• 100-years of public access to the Bluff and beaches will be denied. • Over time, sea level rise will cause engineering structures to fail and fall onto the beaches. • The Coastal Commission’s legal authority will be undermined if a thorough and independent environment impact review, as required by law, does not happen.

UNANSWERED QUESTIONS (see page 12 and Appendices B and C) • Numerous science and engineering questions about the plans remain unaddressed. • The engineering of the proposed structures is excessive and unproven. • Objective analysis is lacking and needed, and requires SANDAG/NCTD public response. • An Environmental Impact Report (EIR) must be done, as required by CEQA and the Coastal Act.

AN ALTERNATIVE
• Do a 10-year project, not 20 to 30-year. The railway relocation must be started now. • Don’t destroy the Bluff and the beaches. Less destructive engineering is possible.

To protect and preserve the Bluff, a 10-year timeline for railway relocation must be implemented now with far less destructive interim engineering. The beauty of this last remaining natural coastal Bluff in San Diego’s North County demands conservation for future generations.

June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 3 OVERVIEW
The Del Mar Bluffs are the last remaining stretch of 1.7 miles of natural terrain trails in San Diego North County. The Bluff and beaches have had continuous community access for over a century.

The 20 to 30-year engineering plan proposed by the San Diego Association of Governments (SANDAG) and the North County Transit District (NCTD) will irrevocably damage the Bluff and beach and also deny access to the wide community of the public who have used them for 100 years.

This Report is addressed to the California Coastal Commission and concerned governmental, nongovernmental, and citizen groups who have the means to question and challenge the engineering plans and ultimately to protect and preserve the natural Bluffs with the open beaches below for future generations.

The Report raises critical scientific and engineering questions related to the on-going and proposed engineering of the Del Mar Bluffs and beaches. Further, the Report will educate and inform stakeholders who question the engineering plans.

Appendices provide expanded material on the questions and issues that need review by Coastal Commission staff and engineers, and by concerned public and private groups.

Our Objectives
Protect and Preserve the Del Mar Bluffs & Beach
• Visualize:
o Simulations of what is planned
o Engineering underway now
• Raise Unanswered Scientific & Engineering Questions
• Define Critical Issues Ensuring they are Objectively Addressed We Call on the Coastal Commission to
• Ensure that SANDAG and NCTD Proposed Plans Are Subject to an Environmental Impact Report (EIR) by objective and expert engineers and scientists; and • Ensure that the California Coastal Commission (CCC) legal mandate to protect the California Coastline is not hampered or superseded by legal maneuvers with the Surface Transportation Board.

June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 4 Urgent Action Required WITHOUT Excessive Measures
Del Mar, SANDAG and NCTD have a multi-faceted problem, 20 years in the making. Why should the lack of adequate progress relocating the railroad result in the destruction of the Del Mar Bluff and its beaches in San Diego’s North County?
The Bluff is fragile and will continue to erode and collapse. It is understood and accepted that some degree of protection is needed to ensure the safety of the railway line that currently runs the 1.7 miles of the Bluff. Nevertheless, the Bluff offers multiple benefits to the community as one of the San Diego region’s last remaining natural, accessible coastal bluff with trails above and beach below. Irreversible changes must be avoided.

The consequences of planned structures will deface the bluffs with armoring and grading, bury beaches and bluff toes behind seawalls, and deplete natural sand replenishment. This Report strongly questions the 20 to 30-year engineering plans as excessive and unproven.

Alternatively:

Relocate now. The railway line runs through Del Mar as a single track on top of the fragile bluff.

The need for relocation has been recognized for over twenty years. Sea level rise and climate change have sped up the urgency. The tracks must be moved within the next 7 years without further delay.

Minimize interim engineering. In the interim, the extent of the proposed engineering requires thorough, objective scrutiny by independent engineers and coastal bluff and beach processes scientists to ensure minimal long-term impact on the Bluff with appropriate mitigation.

Requests to all responsible agencies and individuals:
• Ensure enforcement of Coastal Commission legal mandates • Require an Environmental Impact Report from SANDAG and NCTD • Minimize engineering to save the natural coastal Bluff, beaches, and access
• Relocate railroad tracks no later than 7+ years
• Commit funds to reverse the engineering impacts after relocation June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 5 WHAT IS PLANNED?
SANDAG leads a project to impose environmentally destructive engineering structures along the entire 1.7-mile coastal Bluff top, face, and toe and the beach below that will:
• Armor the entire Bluff with long continuous seawalls on the beach that will eliminate the natural chiseled contours of the Bluff toe and obscure flow of beach sand; • Bury beaches behind the seawalls with in-fill dirt on top of beach sand and Bluff toes; • Destroy bluff faces extensively with grading and compaction that will erase the existing natural bluff geologic features;
• Construct long retaining walls at the coastal bluff-top edge, west of tracks; and • Decapitate completely the upper ~25% of the highest west-facing Bluff face.

NCTD leads a separate project to install fencing on the Bluff tops for the full 1.7 miles.

On October 15, 2021, Del Mar Council members and staff walked the entire length of the SANDAG bluff project together with SANDAG and NCTD engineering staff and one NCTD Board member.

At that time, SANDAG staff indicated the engineering consultants had been directed to plan for another 20 years of train operations atop the fragile, sensitive coastal Bluff (Figure C-3, Appendix C).

COMMUNITY RESPONSE
A Citizens’ Petition submitted to the California Coastal Commission, October 13, 2021, clearly states the community’s concerns regarding the unique qualities of the Del Mar Bluffs and beaches that draw tens of thousands of visitors to walk, swim, surf, and enjoy (Appendix D). The Petition was uploaded to change.org to collect signatures electronically.

Many environmental impact concerns and questions about the fencing project are addressed in the Petition. Further questions were raised by independent third-party engineering experts from Atlas Technical Consultants, LLC, contracted by the City of Del Mar (Appendix B).

Residents of Del Mar, other San Diego communities, and from afar, have presented objections to the excessive engineering plans of SANDAG and NCTD in public meetings before the Del Mar City Council, the California Coastal Commission (CCC), North County Transit District (NCTD), and the San Diego Association of Governments (SANDAG) (See verbal and written Public Comments at meetings of these bodies during the week of Oct. 18, 2021).

This Report poses critical, unanswered questions to ensure they are objectively addressed now.

June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 6 OVERSIGHT IS LACKING
The geotechnical stabilization plans offered by SANDAG and NCTD are unproven, excessive, and plan for 20 to 30 more years of bluff top railroad operation. The community demands a shorter timeline in which the railroad tracks go elsewhere, and the natural Bluff beauty remains.

The community realizes that some preventive engineering is required as soon as possible to protect the tracks and trains before they are relocated. However, the community demands that current engineering in process and planned engineering receive the full scrutiny required by the California Coastal Act. Irreversible changes must be avoided.

NCTD’s approach to fencing the bluffs has disregarded the community and the importance of the natural coastal bluff and beach environment. Their reliance on a cursory geological opinion to justify massive drilling, imposition of concrete and fencing on the Bluff serves as a stark lesson that the Coastal Commission must not rely on the assurances of either NCTD nor SANDAG nor their consultants that their proposed sweeping redesign of the Bluff are the least most destructive and necessary to accomplish legitimate goals.

Dramatic, permanent changes are planned and underway without environmental review. They are a blow to the environment, armoring the Bluff with ugly concrete structures and seawalls creating a gauntlet to beach access: a direct violation of the Coastal Commission’s legal authority and mandate.

THE BOTTOM LINE
Why do a 20 to 30-year project when the track relocation is expected within 10 years? Why destroy the Bluff and beaches when less destructive engineering is possible to bolster the Bluff until the railway is moved? The Coastal Commission has the legal
mandate and singular mission to
protect our precious California coast
June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 7 A Brief Visual Tour in Five Images

1. Proposed Engineering Ignores Coastal Protections
Visualization looking north along the Bluff from 11th St north to Coast Blvd.

IMPACTS:
• Grading and terracing will replace natural Bluff contours with industrial faces. • All red shaded areas will turn into artificial graded slopes. • High seawalls (purple) will obscure the base of the Bluff along the beach.

See Appendix A for more visualizations.

June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 8 2. Continuous Seawalls Restrict Beach Access & Sand Renewal Visualization looking south between 15th and 11th Streets.

IMPACTS:
• A long high seawall (purple) will block natural coves and bluff/beach features. • Long seawalls 8 to 10 feet high will separate beachgoers from the Bluff’s lively life. • Bluff environments for small animals, wild plants, sea grasses, nesting birds, native frogs, and their ecosystem will be buried and obstructed.
• A walk along the beach will change completely - the Bluff will be caged behind a vertical wall.

See Appendix A for more visualizations.

SANDAG’s plans ignore zoning
ordinances certified by the Coastal
Commission that limit protective
structures west of the middle of the
railroad track
June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 9 3. Natural Beauty Will Be Irreversibly Destroyed
Natural Bluff from 11th to 8th St is slated to be decapitated. (photo, Terry Gaasterland) IMPACTS:
• SANDAG plans will remove the top 20 to 25 feet of tall natural Bluff. • Bluff crevices where birds nest and small animals live will be gone forever. • Bluff material for sand replenishment will be eliminated.

June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 10 4. Engineering Already Underway
SANDAG’s Terracing At South End of Del Mar Woods. (photo, Terry Gaasterland) With no environmenal review or public input whatsoever, SANDAG commenced with a small emergency repair that has grown into an outsized insult on the natural bluff face.

June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 11 5. Armoring The Coast – Natural Beauty vs. Concrete Hardening BEFORE: Coastal Bluff Top Trail below Del Mar Woods. (photo, Michael Keenan) AFTER: Bluff Top Trail - Concrete drainage, natural flora/terrain scraped. (Photo, Payson R. Stevens)
June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 12 CRITICAL QUESTIONS
The Coastal Commission needs to require that these critical questions about impacts be answered by SANDAG and NCTD before moving forward. Without an EIR, the consequences of the engineering can never be fully understood and addressed.

1. What is the time horizon for the engineering before the railway is moved as that should determine the degree of armoring needed? What’s the difference and impacts between a 20 to 30-year engineering plan versus a 10-year plan?

2. How will grading and in-fill be managed and minimized?

3. Can the project be reframed to place localized seawalls in high-risk locations? The risk of bluff slide and erosion is not the same along the entire Bluff. Collapses are punctuated, local events.

4. How will imminent sea level rise affect the beaches and proposed seawalls?

5. Are funds set aside to remove seawalls after railroad relocation.

6. Does SANDAG have jurisdiction to construct seawalls on the beach and bury coves behind them?

7. Have agencies with jurisdiction over the beach been included in the planning? For example, State Parks, the State Lands Commission, and the City of Del Mar. The southernmost planned seawall is on the Torrey Pines State Beach

8. Has SANDAG studied the impacts of the seawalls on wave energy dissipation patterns and erosion dynamics? How significant will the resulting active beach erosion be?

9. What serious and committed efforts are underway to relocate railroad in 7 to 10 years?

10. Will the proposed engineering plans be made consistent with the planned train relocation? Appendix C provides expanded details for each Critical Question.

At this time no Environmental
Impact Report (EIR) has been
prepared for
either agency’s project.

June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 13 SUMMARY OF SCIENTIFIC QUESTIONS AND ANALYSIS NEEDED
Geotechnical Impacts
Expert analysis of geotechnical impacts of the SANDAG’s proposed engineered structures are clearly lacking and must be done. The City of Del Mar contracted an independent review of NCTD’s geotechnical report by Leighton Consulting, Inc (2021) on their 1.7 miles of fencing plans.

The independent review found multiple, serious deficiencies. Specifically, the critique of the Leighton report by third-party expert consultant Atlas Technical Consulting, LLC, noted analysis, tests, and measurements that were missing from the Leighton report.

The Atlas observations on needed geotechnical analysis pertain not only to the NCTD fencing but more generally to any engineering project on the fragile coastal Bluff. The following needs for analysis of geotechnical impacts apply equally to the SANDAG engineering. See Appendix B for these fundamental geotechnical questions that must be answered.

Details for the above scientific concerns can be found in Appendix C.

Pressing questions and impacts must be addressed and require SANDAG’s public response.

Urgent Analysis is Lacking in Key Scientific Areas:
• Rain and irrigation subsurface Bluff penetration
• Latest technology for assessing Bluff geology
• Beach erosion effects from seawall construction along Bluff toe • Sea level rise with wave energy against sea walls
• Identification of flora and fauna of Del Mar Bluff and beaches • Vibration effects on coastal Bluff west of tracks
• Seismic risks and the Rose Canyon Fault
• Other adverse consequences (make specific – TG)
June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 14 REPORT DISTRIBUTION LIST
Coastal Commissioners
Coastal Commission Executive Staff
San Diego County Board of Supervisors
Copied to:

State Assembly Representatives and Senators for San Diego Region Federal Congress Members for San Diego Region
Council Members, Mayors and City Managers of San Diego Coastal Cities California Department of Transportation
California Department of Parks and Recreation
Sierra Club
Surfrider Foundation
San Diego Habitat Conservancy
Torrey Pines Conservancy
June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 15 TABLE OF CONTENTS
Overview 2-3
What is Planned? 4
Community Response 4
Oversight Is Lacking 5
The Bottom Line 5
Visualizing the Issues & Problems 6-10
• Simulations
• Photos of Engineering Underway
Critical Questions 11
Summary of Scientific Questions and Needed Analysis 12

APPENDICES
A. Visualizing Issues, Impacts, & Problems 16-44
B: Third Party Geotechnical Analysis Needed 45-47
C. Scientific Questions & Impacts Not Addressed 48-58
D: Citizen’s Petition 59
E. EIR Regulatory Requirements 60
F. Credits and Authorship 61-62

REPORT ORGANIZATION
To define what is lacking to date and the elements of this Report, concerned citizens are in ongoing discussions with geologists and scientists who study coastal processes to examine the multiple engineered structures and changes proposed in the two projects.

This Report seeks to present a more accurate visual simulation of the proposed NCTD and SANDAG engineering and pose scientific questions and concerns about environmental impacts.

Their details are presented in Appendices A through D.

Appendix A visualizes the issues and problems through simulations and photographs.

Appendix B provides the independent third-party expert (Atlas Technical Consultants, LLC) critique of NCTD’s proposed fencing and relates it to SANDAG.

Appendix C expands on the scientific environmental impact questions not addressed publicly in the planning process to date.

Appendix D summarizes and links to the Citizens Petition to the California Coastal Commission.

June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 16 APPENDIX A: VISUALIZING ISSUES, IMPACTS, AND PROBLEMS Included here are our photo simulations that present realistic visualizations from multiple perspectives for the SANDAG-led project. Our visualizations were created using Google Earth and use the locations shown in SANDAG/NCTD engineering plans (as prepared by HNTB, July 2021, SANDAG contract no. 5007812).

These visualizations are general approximations and do not show any specific details of engineering structures planned by SANDAG. They offer bird’s eye views showing the full extent of the bluff and beach areas, including closer views of locations with highest concern. Elevations ranged from sea level to 79 feet at the bluff face highest point.

Expected consequences of proposed engineering are listed as IMPACTS beneath each visualization, summarized as follows:

Impacts of Seawalls Along the Bluff Toe and Grading the Bluff Face • Natural Bluff face will be erased by extensive grading, in-fill behind seawalls, terracing and compaction of bluff material.
• Natural Bluff/beach contours will be buried under in-fill dirt behind seawalls. • Large swaths of natural beach areas will be buried by in-fill dirt. • Existing large “cove” beaches will be buried and eliminated. • Sand loss and beach erosion will be accelerated not slowed down. • At high tide, beach users will have no space to escape “sneaker waves”. • Natural sand deposition on contoured bluff toes will be eliminated.

Impacts on Public Views and Beach Experience
• Natural public views will be demolished.
• Continuous manmade structures will eliminate beach access from historic bluff-top trails in continuous use for over 100-years.
• Retaining wall at top will diminish view of bluff from beach level. • Retaining wall will eradicate the natural view of the bluff from the “upper bluff” to the east of the tracks.
• Natural views from Sea Grove Park and paths will be destroyed. • Natural beach experience will be replaced by cavernous, continuous seawalls with no natural surfaces or contours along the beach.
• A walk along the beach will feel like walking along an industrial corridor with the bluffs caged in behind engineered structures
June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 17 Impacts of Bluff Top Decapitation
• The current high bluff above the beach provides stunning beauty and geology to the Del Mar South Beach experience from the beach.
• Removal of the bluff top will erase this experience forever. • Natural high bluff face will be gone entirely.
• Removal of the cliff will lower the bluff edge 10-15 feet. • Approximately ~620,000 cubic feet of cliff material will be removed (23,000 dump truck loads).
• Removing overburdening will increase the risk of slide by removing buffer material. (Does this offset any decreased risk due to removal of weight?) • Any removed material should be placed on the beach to prevent erosion.

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Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 18 Figure 1. Visualization of Del Mar Bluff Engineering from 15th to 8th St Red shaded areas show slopes to be graded. Seawalls with back-fill on the beaches behind and graded slopes above stretch the entire length of the coastal bluff toe. New seawalls at bluff base, 8-foot height. Bluff top, 61-65 feet above sea level. (Note: Green pins mark consistent locations across simulations. Yellow pins mark specific engineered structures.) June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 19 Figure 2. Visualization of Del Mar Bluff Engineering, Sea Grove Park south to 7th St.

Continuous seawall (black) along the toe of the bluffs, approximately 8 feet high. Red shaded areas show graded slopes. Bluff top, 61-65 feet above sea level. (Note: Green pins mark consistent locations across simulations. Yellow pins mark specific engineered structures.) June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 20 Figure 3. Visualization of Del Mar Bluff Engineering, looking north from 7th St to Sea Grove Park (15th St)
Continuous seawall (black) along the toe of the bluffs, approximately 8 feet high. Red shaded areas show graded slopes. Bluff top, 61-65 feet above sea level. (Note: Green pins mark consistent locations across simulations. Yellow pins mark specific engineered structures.) June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 21 Figure 4. Engineering Plans for Del Mar Bluffs and Beaches, Google Earth overlay Image overlaid with SANDAG Initial Engineering Plans (as prepared by HNTB, July 2021, SANDAG contract no. 5007812), basis for visualizations.

June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 22 Figure 5. Del Mar Bluff Engineering, 15th St to 11th St Continuous seawall (purple) along the toe of the bluffs, 8-foot height. Red shaded areas show graded slopes. Yellow pins mark each engineering region with its seawalls, back-fill, and graded slopes. Bluff top, 61-65 feet above sea level. (Note: Green pins mark consistent locations across simulations. Yellow pins mark specific engineered structures.) IMPACTS:
• Natural beach contours will be destroyed by new in-fill dirt behind the seawalls. • Natural bluff face will be erased by extensive grading and compaction. • Natural public views will be demolished.
• Continuous manmade structures will eliminate beach access from historic bluff-top trails in continuous use for over 100-years.

June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 23 Figure 6. Del Mar Bluff Engineering, 15th St to 12th St Continuous seawall (black) along the toe of the bluffs, 8 foot height. Red shaded areas show graded slopes. Yellow pins mark specific engineered structures, including seawalls, back-fill, and graded slopes. Bluff top, 61-65 feet above sea level.

IMPACTS:
• Note extensive grading and in-fill behind seawalls
• Natural views from Sea Grove Park and paths will be destroyed. • Terracing on graded slopes will eliminate natural bluff face contours. • Bluff/beach contours will be buried under in-fill.

June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 24 Figure 7. Del Mar Bluff Engineering, Seawall at Beach Level below 15th St to 11th St Continuous seawall (purple) along the toe of the bluffs, 8-foot height. Red shaded areas show graded slopes. Yellow pins mark specific engineered structures, including seawalls, back-fill, and graded slopes. Bluff top, 61-65 feet above sea level.

IMPACTS:
• Natural beach experience will be replaced by cavernous, continuous seawalls with no natural surfaces or contours along the beach.
• A walk along the beach will feel like walking along an industrial corridor with the bluffs caged in behind engineered structures.
• Natural sand deposition on contoured bluff toes will be eliminated. • Large swaths of natural beach areas will be buried by in-fill dirt.

June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 25 Figure 8: Removal of High Coastal Bluff Top, 11th St to 8th St Red shaded area - to be removed. Current high bluff top, over 80-feet above sea level.

IMPACTS:
• The current high bluff above the beach provides stunning beauty and geology to the Del Mar South Beach experience from the beach.
• Removal of the bluff top will erase this experience forever.

NOTE: Trails along this stretch have already been blocked with demarcation fencing and extensive signage which should be maintained and expanded to protect the bluffs and citizens.

June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 26 Figure 9: Removal of high coastal bluff top, 11th St to 8th St - Detailed View Gray rectangles indicate bluff berm level after removal. Red shaded areas show bluff to be removed. Yellow pin marks northern boundary of engineering region. High bluff top, over 80-feet above sea level. Railroad tracks, 61-65 feet above sea level.

IMPACTS:
• Natural high bluff face will be gone entirely.
• Substantial amounts of bluff material will no longer be available to expand the width of the bluff after a slide and thus fight bluff erosion.
• Bluff material will no longer be available to replenish beach sand. • Removing overburdening will increase the risk of slide by removing buffer material. More critically, it will undermine the cliff and tracks without any geology assessment/survey.

June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 27 IMPACTS (Figure 9 continued)
• SANDAG reports risk of bluff slide will reduce by a mere predicted 10% based on models and projections. Have the models been critiqued or validated? • Note the difference between the straight-line seawall (purple) and the natural bluff-toe contours.
• Removal of the cliff will lower the bluff edge 10-15 feet. • Approximately ~620,000 cu ft of cliff material will be removed (enough to fill 23,000 dump trucks).
• Any removed material should be placed on the beach to prevent erosion.

June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 28 Figure 10: Seawall from 8th St to 7th St with in-fill and grading - View A Seawalls (purple) along the toe of the bluffs, 8-foot height. Red shaded areas show graded slopes.

Yellow pins mark each engineering region with its seawalls, back-fill, and graded slopes. Bluff top, 61-65 feet above sea level. (Note: Green pins mark consistent locations across Views A-D) Note: cliff slope back fill, and elimination of existing “cove” beach behind SEAWALL 4 IMPACTS:
• Existing 2000 sq ft large “cove” beach behind SEAWALL 4 will be buried and eliminated. • Smaller “cove” beach behind SEAWALL 5 will also be buried and eliminated. • Natural contours of bluff toe along beach will be eliminated. • At high tide, beach users will have no space to escape “sneaker waves”.

June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 29 Figure 11: Seawall on Beach from 8th St to 7th St with in-fill and grading – View B Seawalls (purple) along the toe of the bluffs, 8-foot height.Red shaded areas show graded slopes.

Yellow pins mark each engineering region with its seawalls, back-fill, and graded slopes. Bluff top, 61-65 feet above sea level.

IMPACTS:
• See Figure 9 and 10 impacts.
• Retaining wall at top will diminish view of bluff from beach level.

June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 30 Figure 12: Seawall from 8th St to 7th St with in-fill and grading - View C Seawalls (white dashed line) along the toe of the bluffs, 8-foot height. Concrete retaining wall (black dashed line) along top of bluff. Red shaded areas show graded slopes. Yellow pins mark each engineering region with its seawalls, back-fill, and graded slopes. Bluff top, 61-65 feet above sea level.
*Visual Simulations courtesy, Payson R. Stevens. Contact XXXX (e.g. Save Our Bluffs) for use.

IMPACTS:
• See Figure 9 impacts.
• Retaining wall will eradicate the natural view of the bluff from the “upper bluff” to the east of the tracks.
• Natural contours will be demolished at the top and bottom of the bluff.

June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 31 Figure 13: Seawall at Beach Level from 8th to 7th St with in-fill and grading - View D Seawalls (purple rectangles) along the toe of the bluffs, 8-foot height. Red shaded areas show graded slopes. Yellow pins mark each engineering region with its seawalls, back-fill, and graded slopes. Bluff top, 61-65 feet above sea level.

IMPACTS:
• See Figure 9 and Figure 12 impacts.
• Sand loss and beach erosion will be accelerated not slowed down.

June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 32 Figure 14: SANDAG Rendering of Seawall at Anderson Canyon extending north to 4th St with in-fill and grading on bluff face.

Seawall along toe of the bluffs, 8-foot height. Bluff top, 61-65 feet above sea level. * SANDAG rendering presented to Del Mar City Council 9/20/21 IMPACTS:
• Natural beach experience will be blocked by continuous seawalls. • A walk along the beach will feel like walking along a cage. • Natural sand deposition on contoured bluff toes will be eliminated. • Natural beach areas will be buried by in-fill dirt.

June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 33 PHOTOS: Engineering Impacts-underway or planned
This section presents photographs of existing bluff conditions, including emergency repair engineering underway (Figures 15-18) and shows current conditions where engineered structures are proposed (Figures 19-24).

The photos shown were shared by Del Mar’s community of bluff and beach visitors. Many come from near and far to marvel at the vistas, absorb the every-changing sunrises and sunsets, walk the trails, descend the bluffs to swim, surf, jog, walk or just peacefully sit in the splendor of Nature on the Del Mar Bluffs where the edge of North America meets the Pacific. To deny them the potential loss of this century-old access is not only violation of their historical rights but those enshrined legally by the California Coastal Commission.

June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 34 Figure 15: UNDERWAY: SANDAG’s Terracing At South End of Del Mar Woods. (Sept. 5, 2021; photo, T. Gaasterland)
June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 35 Figure 16: SANDAG’s Interim Drainage Engineering South of Del Mar Woods. (Sept. 5, 2021; photo, T. Gaasterland)
Note water drainage of 5 gallons per minute pouring out of the bluff from yet unknown sources.

June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 36 Figure 17. Seawall construction below Del Mar Woods south of 4th St. (Photo, Udo Wahn)
June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 37 Figure 18. Seawall construction below Del Mar Woods south of 4th St. (Photo, Udo Wahn)
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Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 38 Figure 19. Natural Bluff Today Without Engineering, area to be decapitated (September, 2021; photo, T. Gaasterland).

June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 39 Figure 20. Natural Beach Today at 7th St to 8th St (known as Mango Reef), area to be buried behind extended seawall (October, 2021; photo, T. Gaasterland).

This beach shown at a high high-tide will be lost behind the seawall planned below 7th St to 8th St.

No beach will remain at this location at high tide.

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Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 40 Figure 21. Bluff Avian Visitors

Peregrine Falcon (Photo, Udo Wahn)
Blue Heron, 11th Street (Photo, Al Tarkington)
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Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 41 Figure 22. Natural Beauty (Photos: Payson R. Stevens: top, bottom left; Karl Willet: bottom right) June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 42 Figure 23. Natural Erosion vs Concrete Armor (Photos: Payson R. Stevens) Upper Bluff: Natural Chiseled Features
Upper Bluff: Concrete Terracing
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Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 43 Figure 24. Natural Beauty vs. Concrete Armor
BEFORE: Coastal Bluff Top Trail at South End of Del Mar Woods.

The trail has already been scraped by the emergency terracing. (Photo, Spring, 2017, Michael Keenan)
AFTER: Upper Bluff: Concrete drainage, natural flora and terrain scraped. (Photo, P.R. Stevens)
June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 44 APPENDIX B: THIRD-PARTY GEOTECHNICAL ANALYSIS NEEDED Expert analysis of geotechnical impacts of the SANDAG’s proposed engineered structures are lacking and must be done. The City of Del Mar contracted an independent review of NCTD’s brief geotechnical statement from Leighton Consulting, Inc (2021) on the impacts of fencing structures along 1.7 miles of fragile coastal bluff. The independent review found multiple, serious deficiencies. Specifically, the critique of the Leighton report by third-party expert consultant Atlas Technical Consulting, LLC, noted analysis, tests, and measurements that were missing from the Leighton report.

The Atlas observations on needed geotechnical analysis pertain generally to any engineering project on the fragile coastal bluff, not only to the NCTD fencing project. The following needs for analysis of geotechnical impacts apply equally to the SANDAG engineering:
• Needs discussion of geologic hazards, slope stability, and landslide potential. Drilling and other engineering proposed (piers, fencing, etc) in sensitive bluff segments could weaken bluffs.
• Needs discussion or anticipation of subsurface rock with distinct characteristics (e.g. geologic units) affecting bluff stability.
• Needs customary practice of descriptive survey and sampling of bluff geology (e.g. mapping, hand augers, geophysics, or other invasive or non-invasive exploratory geologic methods).
• Needs geologic descriptions and geologic cross-sections along the bluff top, geologic unit thickness, bedding, structure, groundwater, and other critical geologic conditions relevant to the site conditions.
• Needs description regarding lateral support, confinement and /or bearing support of the planned engineering.
○ Needs stated expert opinion regarding bluff-top stability and the potential for reducing the factor of safety for global and surficial stability of the bluffs where planned improvements will be located and may surcharge the bluffs. ○ Needs discussion of iron oxidation and impact of corrosion on engineering foundations.

These required analyses are needed not only for the NCTD fencing but also for the SANDAG Bluff Stabilization Structures.

Atlas provided the following two-page critique with unanswered questions:

June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 45 6280 Riverdale Street
San Diego, CA 92120
(877) 215-4321 | oneatlas.com

WORK PRODUCT
September 30, 2021
Atlas No. 190320P5.6
Report No. 1
MR. BILL PATE

CITY OF DEL MAR
2240 JIMMY DURANTE BOULEVARD
DEL MAR, CALIFORNIA 92014
Subject: Third Party Geotechnical Review
Proposed Security Fencing – Del Mar Bluffs, Del Mar, California Reference: Leighton Consulting, Inc. (2021), Geotechnical Review of Proposed Security Fencing – Del Mar Bluffs, Del Mar, California, February 5.

Dear Mr. Pate:

In accordance with your request, Atlas has reviewed the referenced geotechnical review prepared by Leighton Consulting, Inc. (2021) and have the following questions and comments.

1. The geotechnical consultant provides an opinion stating that “the proposed security fence with small diameter foundations backfilled with PCC will not impact the stability of the bluffs or the trackbed support, nor promote additional erosion/bluff retreat.” The consultant does not discuss the potential impact that the construction aspect of the project, including site access/egress, vehicular traffic, and construction equipment vibrations may have on the stability of the bluffs, trackbed support, and whether or not the construction aspect of the project may promote additional erosion/bluff retreat.

2. The consultant does not discuss geologic hazards, including slope stability and the potential presence of landslides. The sensitive segments of the bluff could be affected by drilling a large number of piers, creating a weakened plane.

3. The consultant does not discuss anticipated subsurface conditions (i.e. geologic units).

4. The consultant does not recommend a minimum horizontal distance to daylight from the proposed western fence alignment post foundations towards the face of nearby slope/bluff.

5. The local geology should be more descriptive and supplemented with mapping, hand augers, geophysics, or other invasive or non-invasive exploratory geologic methods which are customary and part of local practice. Provide localized geology descriptions and geologic cross-sections along the bluff top presenting the thicknesses of geologic units, bedding, structure, groundwater, and other geologic information pertinent to the site conditions.

6. Provide a narrative regarding lateral support, confinement and /or bearing support of the planned improvements.

7. Provide an explicit opinion regarding bluff-top stability and the potential for reducing the factor of safety for global and surficial stability of the bluffs where planned improvements will be located and may surcharge the bluffs.

8. Provide corrosion criteria related to ferrous metals and concrete regarding foundations.

June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 46 Atlas No. 190320P5.6
Report No. 1
Page | 2

WORK PRODUCT

9. The design engineer should provide a constructability exercise with equipment and method requirements to reduce the assumptions made during initial design and support those conclusions and recommendations with field surveys and geotechnical data.

10. Foundation design should also address particular challenging segments of the alignment that have ongoing stability issues, sensitive habitat, or existing improvements. Recommendations in those areas should offer foundation design recommendations and provide sufficient engineering guidance to facilitate installation.

11. All surcharges existing and planned should be addressed in the design. Operational and construction vibrations on the planned foundations should also be addressed.

12. Bioturbation and biotechnical slope protection should be addressed in the design.

In our opinion, the referenced geotechnical documents should not be accepted until the questions and comments above are satisfactorily addressed. If you have any questions, please call us at (619) 280-4321.

Respectfully submitted,
Atlas Technical Consultants LLC
Andrew K. Neuhaus, CEG 2591 Andrew T. Guatelli, PE, GE 2320 Chief Geologist Principal Engineer
Greg Wilson, PG 9777
Project Geologist
GW:ATG:AKN:ds
Distribution: [email protected]; [email protected]
June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 47 Appendix C: Critical Scientific Questions & Impacts Not Addressed Critical Science Questions of Concern Needing SANDAG Response • Rain and Irrigation Impacts (Figure C-1)
○ What are the impacts of surface water penetrating to deeper groundwater? ○ Where is the imperious layer and how will it impact bluff slide? ○ What is the probability of increased risk of bluff slides? ○ Where is the data?
○ How are they being studied and addressed?
○ French drains on the east side at 11th St have helped to reduce risk. Can they go deeper?
Figure C-1. Bluff Erosion. Groundwater from multiple sources moves through pervious material, saturates cliff edge soil, and increases landslide risk.

Figure Courtesy: Shore Friendly, http://www.shorefriendly.org/your-erosion-risk/on-bluffs/ • Use of Latest Technology to Assess Bluff Geology Impacts ○ How is the latest coastal bluff geologic technology being used to assess the bluffs critically vulnerable regions?
○ SANDAG assessment can take advantage of LIDAR studies ○ SANDAG assessment can use strainmeters (optical-fiber equipment) at key locations along the cliffs, capable of measuring earth movements at the scale of microns.
○ SANDAG assessment can use tiltmeters, which measure minute changes in bluff masses potentially providing predictive capability to monitor slope stability.

Reference: https://scripps.ucsd.edu/news/scripps-receives-25-million-lead-new-coastal-cliff-research June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 48 • Excessive Seawall Engineering
○ Research at Scripps Institution of Oceanography (SIO), using LIDAR, has shown there are bluff regions that are more vulnerable than others along the Del Mar beach.
○ SANDAG estimates of cliff erosion rates of six inches per year, are averages over the entire length of the bluff. They are not specific to those areas of the Del Mar Bluffs that are more or less susceptible to wave erosion. ○ SIO research used LIDAR sensors to measure bluff surface distances to mean high tide line. The measurements yielded a bluff steepening index all along Del Mar’s shoreline. The index showed with accuracy and precision that west of 13th, 11th and 9th Streets the coastal Del Mar bluff was most vulnerable to wave erosion based on measurements made during 1998 to 2009 (Figure C-2). ○ The difference between average rate and punctuated erosion events must be explored before the wholesale construction of too many 8 to 10-foot seawalls that are not needed, will reduce sand deposition, and block beach access. ○ To protect the environment and preserve the natural bluff and beach coastline contours, any engineered structures need to use temporary/removable erosion protection methods. Further, increased monitoring to detect railway threats can enable a phased plan, and thus postpone and avoid irreversible measures. ○ These are complicated issues when important infrastructure is involved.

Unfortunately these issues will only become more common as sea level rises.

June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 49 Figure C-2. Localized Bluff Steepening Index Calculated from 1998-2009 Measurements Along Del Mar From North (top) to South (bottom).

Graph of bluff steepening data as reported in A. Young (2020) side by side with satellite Google map of Del Mar coastline. South of 15th St, many of the punctuated high-risk zones at 13th St, 11th St, and 9th St have had slides. This index based on data through 2009 was predictive. The index could be used in the current planning. These data show bluff retreat is punctuated and specific, with measurable prior risk, not averaged across broad ranges.

Reference: Young et al: Three years of weekly observations of coastal cliff erosion by waves and rainfall , November 2020 Geomorphology 375(10):10754 10.1016/j.geomorph.2020.107545 https://www.researchgate.net/publication/347224570_Three_years_of_weekly_observations_of_coastal_cliff_erosion_by_waves_and_rain fall
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Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 50 Figure C-3: SANDAG Draft Design for Seawalls, Typical East-West Slice, with in-fill and grading specifications (2021 design).

Design notes indicate 30-year and 50-year bluff retreat lines; NCTD right of way (R/W) line is ~two-thirds down the bluff face (~30-50 east-west linear feet from middle of track [MT]); soldier piles up to 65’ deep; 10 to 15-foot high seawalls with embedment to -17 feet below sea level (0 feet on y-axis Elevation); graded slope with 1.5:1 ratio (horizontal:vertical ratio).

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Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 51 • Questions about Draft Design for Seawalls (Figure C-3) o What are the following metrics based on?
• 30 year bluff retreat line
• NCTD R/W midway down bluff face, ~30-50 feet west of soldier piles • 40-65 foot depth for soldier piles
o What will be the impact on the bluff to drive in soldier piles that are as deep as the bluff?
o How many 3-foot diameter soldier piles are planned and at what distance apart?
o Have they calculated separate local bluff retreat projections at each engineering location? Bluff retreat is punctuated, not averaged over the entire bluff face. o What is the source to establish mean-tide-line (x-axis)? o What review will happen to assess consistency with shoreline protections in the City of Del Mar? This design violates private easements between 10th and 11th Streets and also the Shoreline Protection Act (SPA) line in Del Mar’s zoning, certified by the Coastal Commission, which prohibits protective structures west of the middle of the tracks (MT).

June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 52 • Sand Deposition Impacts
○ Seawalls along natural coastal bluffs result in loss of sandy, recreational beaches.

Armored bluffs in Solana Beach and Encinitas have shown beach loss over time. ○ How much sand nourishment will be lost due to continuous bluff-toe seawalls? Appendix B of the City of Del Mar’s Sea Level Rise Adaptation Plan provides an analysis of coastal processes and sand movement along the Del Mar shoreline and presented the following observation that must be followed up to inform this question: In Del Mar, approximately 75% of sediments in the sea cliffs are large enough grain size to contribute to the beaches.
○ Instead of seawalls, can soldier piles accomplish the goal of interim bluff stabilization with lesser environmental impact? The Plan notes, [NCTD] determined that installing soldier piles was the least environmentally damaging feasible alternative for an interim approach to track bed stabilization. ○ How much will soldier piles increase instability by driving 36-inch diameter piles 50-60 feet down into the cliff? How close will they be to each other? ○ Instead of seawalls or soldier piles, can other technologies be used? Will they provide better protection? The Plan discusses Detached Breakwaters and Reefs, Groins, and Dunes as alternatives to protect against bluff erosion. ○ During 2014-2018, the City of Del Mar studied impacts of sea level rise on the Del Mar Coastal Bluffs (Chapter 7, SLR Coastal Adaptation Plan, adopted by Council into the Community (General) Plan, October 1, 2018).1 The Plan’s Chapter 7 assessed the Del Mar Bluffs, built upon a Vulnerability and Risk Assessment2 , and
provided the following summary observations about vulnerability:

Vulnerability assessment:

With 1-foot of sea-level rise, the current localized vulnerability of the LOSSAN railroad to bluff erosion will increase and extend along almost the entire southern bluffs. The railroad would need to be moved inland or other adaptation measures, for example with underpinnings, caissons, or soldier piles, would be required to reduce the risk of the railroad collapsing. ● If a seawall is constructed to protect the railroad, it will cause the beach to narrow and over time little to no beach will exist along the southern bluffs.
o Del Mar’s Sea Level Rise Adaptation Plan recommends the following Bluff adaptation options: Beach nourishment and retention; Railroad relocation; Public infrastructure relocation
Sources:

1. https://www.delmar.ca.us/DocumentCenter/View/3580/Revised-Adaptation-Plan-?bidId=

2. https://www.sandiego.gov/sites/default/files/sea-level-rise-vulnerability-assessment.pdf June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 53 • Biota: Flora and Fauna Impacts
o The Del Mar Bluff is a 1.7 mile narrow stretch of non-human colonized land between the two protected lagoons of Los Penasquitos and San Dieguito. Many protected fauna and flora inhabit both of those lagoons and it is very likely that the bluff serves an important function to prevent loss of genetic diversity, a so-called migration corridor.

To remove the bluff corridor can lead to genetic isolation for many species, which will limit their ability to adapt to changing environments, such as global warming, as a result of loss of genetic variability1,2.
o Endangered, threatened, of special concern, or to-watch species of plants and animals that have been observed at or near the bluff include3-5:
§ Plants: Red Sand-Verbena, Short-Leaved Dudleya, Sea Dahlia, Coast Barrel Cactus, Western Dichondra
§ Birds: Coastal California gnatcatcher (non-migratory), Western snowy plover (migratory and non-migratory), Coastal cactus wren (non-migratory), Belding’s savannah sparrow (non-migratory), Least Bell’s vireo (neotropical migratory)
§ Butterflies: Wandering skipper
§ Lizards: Belding’s orange-throated whiptail, California legless lizard, Coronado skink, Coast horned lizard
§ Snakes: Red diamond rattlesnake
o Vernal Pools: The Del Mar Bluff also contains Vernal Pools that are crucial for the survival of its inhabitants. Vernal Pools are covered by shallow water for variable periods from winter to spring, but may be completely dry for most of the summer and fall. Plants and animals that thrive under these harsh conditions spend the dry season as seeds, eggs, or cysts, and then grow and reproduce when the ponds are again filled with water. More than 90% of California's vernal pools have already been lost6. It is important to protect the few remaining vernal pools as they provide habitat to some very rare plant and animal species. In addition, birds such as egrets, hawks and ospreys use vernal pools as a seasonal source of food and water. The vernal pools on the Del Mar Bluff are long and narrow along the eastern side of the bluff, commonly observed midway between 15th and Torrey Pines and have been observed to be used by frogs. To date, the frog species that depend on the vernal pools, for their survival and reproduction, have not been confirmed. They might be Tree Frogs, or also possibly be the endangered species Spade Foot Toad. Other endangered species that might use the vernal pools on Del Mar Bluff are Fairy Shrimp and California Tiger Salamanders since June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 54 they are native to Southern California and are dependent on vernal pools for their reproduction and survival. Frog species should be identified.

References, Sources:

1. Mark R Christie, and L Lacey Knowles (2015) Habitat corridors facilitate genetic resilience irrespective of species dispersal abilities or population sizes. Evol Appl., 8(5): 454–463, doi: 10.1111/eva.12255

2. Harrison, R. L. (1992). Toward a Theory of Inter-Refuge Corridor Design. Conservation Biology, 6(2), 293– 295. http://www.jstor.org/stable/2386251

3. http://www.lospenasquitos.org/conservation/sensitive-species/

4. https://www.calflora.org/entry/observ.html

5. https://calscape.org/

6. https://www.epa.gov/wetlands/vernal-pools

7. http://www.californiaherps.com/frogs/pages/s.hammondii.html

8. https://databasin.org/maps/new/#datasets=443d192368f6409c949338014886c703

9. https://www.fws.gov/sacramento/es_species/Accounts/Amphibians-Reptiles/ca_tiger_salamander/ o Biota: Bluff & Slopes
Have complete species lists for flora and fauna on the Del Mar coastal bluff been reviewed?
a. Do they include any sensitive or endangered natives? b. Where else in San Diego do these native species still exist in natural state? c. What species depend on the Del Mar Bluff as a corridor from lagoon to lagoon?
o Biota: Beach & Intertidal
Have complete species lists for flora and fauna on the Del Mar beaches been reviewed? a. Do they include any sensitive or endangered natives? b. What will be the impacts on shorebirds due to loss of bluff face nesting areas? c. What will be the impacts on grunion runs at top of high tide along the bluffs? Grunion runs need a protected area without lights.
d. What will be the impacts on nighttime fauna and flora? Because the main north beach in Del Mar has extensive lighting, the bluff beaches provide scant dark areas for species active at night.

Bottom Line: Without proper flora and fauna species identification, there is no clear picture of the bluff lifeforms, their surface and subsurface habitats, and their uniqueness.

June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 55 Figure C-4. Vibration Study Map, Entech Consulting (June 2021)

• Vibration Impacts
o SANDAG’s consultant Entech Consulting Group measured vibration east of the tracks on the upper east bluff in 3 locations in June 2021. o The study measured vibration for only a 24-hour period in which two freight trains passed on the Bluff, and sampled in only 3 locations – an insufficient sampling. o Figure C-4 shows the Vibration Study map and measurement locations. o Measurements were at least 100 feet east of the tracks and at least 50 feet from the edge of the each upper bluff on top of surface streets. o Data from the study showed 15 second intervals between measurements, too long a period to sample multiple times during the passing of a train. o Data two of the three sampling points seemed to have duplicate values, indicating some sort of measurement artifact or data processing error. o Entech did not measure vibration in the limestone of the Bluff west of the tracks. o A person standing on the coastal Bluff or the upper east bluff when the train goes by will feel the Bluff vibrate.

June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 56 VIBRATION QUESTIONS:
o What are the effects of vibration from trains within the limestone Bluff over time?
o What will doubling the number of trains do to the effects of vibration? o What will increasing the speed of the trains do to the effects of vibration? o Should the trains run more slowly, not faster?
• Seismic Risk and Impacts
o Rose Canyon Fault: Experts estimate that this active fault, located less than 2 miles offshore from Del Mar’s Bluffs, is the greatest seismic threat to the region as it is capable of earthquakes of magnitude 6.9. In the 1800s, the fault previously generated 6.5 and 6.0 earthquakes that caused widespread coastal bluff slope failures (Griggs and Scholar 1997). According to the Earthquake Engineering Research Institute’s recent scenario of a 6.9 earthquake, “tracks in Del Mar are potentially subject to earthquake-induced bluff failures. Service can be expected to be disrupted for weeks to months while tracks are repaired” (EERI San Diego Scenario 2020, p. 48).
• Stability Impacts
o Assurances needed: According to the Coastal Act’s Section 30253, “new development shall assure stability and structural integrity, and neither create nor contribute significantly to erosion, geologic instability, or destruction of the site or surrounding area or in any way require the construction of protective devices that would substantially alter natural landforms along bluffs and cliffs.” o Fencing: NCTD’s proposed fencing project will drill over 1,000 post holes into the fragile sandstone bluff to create over 1,000 new avenues for water intrusion and add almost 300 tons of weight from cement and fencing on the most vulnerable bluff edges. How does this contribute to erosion and geologic instability? o Heavy Equipment: SANDAG’s project utilizes heavy construction equipment that can cause substantial ground borne vibration from pile drivers and large earthmoving equipment. Given the many fissures on the bluff, how can SANDAG decapitate (or “shave”) over 23,000 cubic feet from the top of the oceanfront bluffs between 8th and 11th St. without damaging them or causing more slides? o Risk/Reward: SANDAG’s engineer stated there is only an expected 10% reduction in bluff slide risk which is a very low risk/reward payoff given the high probability of failure and permanent damage to the long-term stability of the bluffs and train tracks.

June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 57 o Double-Tracking: SANDAG acknowledges that vibrations from increased train traffic along rail ways from the “double-tracking of the LOSSAN railway corridor may also cause or exacerbate soil erosion along coastal bluffs.” (current draft EIR for the 2021 Regional Plan). Will this create more stress on the fragile bluffs lining both sides of the train tracks? Is this what is contributing to the increasing frequency of large slides that now total 9 in the last 3 years, including the most recent on Oct. 29, 2021?
• Permanent Alteration of Natural Land Forms
o Scenic and Visual Resources: According to the California Coastal Act Section 30251, “the scenic and visual qualities of coastal areas shall be considered and protected as a resource of public importance. Permitted development shall be sited and designed to protect views to and along the ocean and scenic coastal areas, to minimize the alteration of natural land forms, to be visually compatible with the character of surrounding areas, and, where feasible, to restore and enhance visual quality in visually degraded areas. New development in highly scenic areas such as those designated in the California Coastline Preservation and Recreation Plan prepared by the Department of Parks and Recreation and by local government shall be subordinate to the character of its setting.”
June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 58 APPENDIX D: Summary of Citizens’ Petition
The following text from the one-page summary of the Citizens Petition to the California Coastal Commission summarizes the overall situation:

For over 100 years, the public has used the trails on the iconic Del Mar bluffs (“Bluffs”).

Despite decades of dangerous bluff collapses, SANDAG and NCTD have failed to take action to relocate the train tracks installed in 1910. SANDAG has finally commenced efforts to relocate the tracks by seeking alternative, inland train routes. In the meantime, NCTD and SANDAG propose to stabilize the Bluffs by grading the Blufftop, erecting concrete structures in the Bluff and making other changes, many irreversible.

Even though the fragile sandstone bluffs are fast eroding, NCTD plans to further destabilize the Bluffs by erecting nearly two miles of six foot chain link fencing along the Bluffs.

This fencing project will require extensive drilling of postholes, to be filled with cement to support the fence. The holes will create more than 1,500 new sources of water intrusion and add 317 tons of weight which accelerates erosion of the already stressed Bluff edges.

While NCTD claims extensive two-mile fencing is required to avoid “trespassers,” NCTD’s data shows that all pedestrian and vehicle accidents occur at or within a third of a mile of the crossing at Coast Blvd and that extensive fencing is unnecessary in addition to destabilizing.

The Petition urges the Coastal Commission to obtain a firm commitment from SANDAG and NCTD to relocate the tracks within a specific time frame--within 10 years--to ensure that alteration of the Bluffs be the minimum necessary to ensure safety until relocation; and to reject NCTD’s proposed fencing plans and avoid further damage to and erosion of the Bluffs through limited, targeted fencing near the Coast Blvd crossing.

Ultimately, it is the Coastal Commission that has the statutory mandate and singular mission and to whom the citizens of California look, to protect our precious coast, in this case specifically the Del Mar Bluffs. SANDAG and NCTD have no similar mandate but rather are beholden to railroad and commerce interests. Certainly, a balance of interests is in order, but SANDAG’s and NCTD’s plans, which they insist are meant to address a “temporary” problem, will inflict permanent damage and place the interests of commerce far ahead of environmental interests and those of citizen’s rights as mandated to the Coastal Commission. This paper asks that the Coastal Commission test SANDAG and NCTD assurances with just some of the scientific questions that need to be asked by the Coastal Commission’s scientists.

Link to full Petition available via https://delmarbluff.com/one-page-summary-of-citizens-petition June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 59 Appendix E: EIR Regulatory Requirements
California Requirements:
• The California Environmental Quality Act – CEQA
o CEQA requires public agencies to “look before they leap” and consider the environmental consequences of their discretionary actions. CEQA is intended to inform government decision makers and the public about the potential environmental effects of proposed activities and to prevent significant, avoidable environmental damage.

Source: CEQA- The California Environmental Quality Act: https://opr.ca.gov/ceqa/ • The California Coastal Act
o Elements of the bluff stabilization project do not meet the following requirements of the Coastal Act in PEIR 4.1:
o Under the California Coastal Act of 1976 (Public Resources Code Sections 30000 et seq.), scenic and visual qualities of coastal areas are considered and protected as a visual resource. One of the primary objectives of the Coastal Act is the protection of scenic and visual resources, particularly as viewed from public places. Section 30251 requires that development be sited and designed to protect views to and along the ocean and other scenic coastal areas. New development must minimize the alteration of natural landforms. This policy also requires that development is sited and designed to be visually compatible with the character of surrounding areas. Where feasible, development must include measures to restore and enhance visual quality in visually degraded areas. o LOCAL LAWS, REGULATIONS, PLANS, AND PO
https://sdforward.com/docs/default-source/2021-regional-plan-draft-eir/4-1-aesthetics-andvisual-resources.pdf?sfvrsn=210ffd65_2 o County of San Diego EIR Requirements
https://www.sandiegocounty.gov/content/dam/sdc/pds/docs/EIR-Format.pdf June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 60 Appendix F: Credits
Authors: Payson R. Stevens & Terry Gaasterland
Text Research/ Content: Biota: Camilla Rang; Seismic & Landforms: Laura DeMarco Text Comments: Drew Cady, John Stahl, Shirli Weiss
Visualization Simulations: Mason Tripp
Satellite views: Google Earth Pro
Design: CorePR.com
Short Biographies
Payson R. Stevens
His multi-faceted career reflects two passions: earth science/environmental protection and art in multiple media (painting, experimental video, photography, writing). Payson did PhD studies at Scripps Institution of Oceanography mentored by the renowned scientist, Roger Revelle. He was instrumental in helping to stop oil development off the coast of San Diego and Orange County organizing and preparing the science assessment and critique of the EIR of Lease Sale 48 (1978). The two companies he founded, InterNetwork, Inc. and InterNetwork Media, Inc. consulted with NASA, NOAA, and the USGS on global change/climate issues (Earth System Science, Mission to Planet Earth/1980-2000). Both companies were pioneers at the beginning of the digital age and received many awards for cutting-edge work (Presidential Design Award for Excellence from Bill Clinton/1994, USGS John Wesley Powell Award/1992). Stevens is the co-author of the acclaimed, Embracing Earth: New Views of Our Changing Planet (1992) and contributing author to the best-selling college textbooks (Biology Today /1971), Geology Today/1973). His public speaking includes TED 2 & 3, CNN, Robert Redford’s Greenhouse/Glasnost, Apple Developers Conference. He lives half the year with his wife, the writer Kamla K.

Kapur (www.kamlakkapur.com), in a remote area of the Indian Himalayas where he is involved with nature conservation and rural community work. His India projects included: advisor to the Great Himalayan National Park/GHNP (2000-15); co-founder of Friends of GHNP (2000-present), successfully spearheading GHNP’s Inscription as a UNESCO World Heritage Site (2014); co-founder of My Himachal (2006-12) which focused on rural healthcare and nutrition. His projects can be seen at www.paysonrstevens.com Terry Gaasterland, PhD
Terry directs the Bioinformatics & Systems Biology Graduate Program at the University of California, San Diego, with tenure, and is a member of the faculty of the Scripps Institution of Oceangraphy. She earned her Bachelor Degree in Computer Science and Slavic Studies at Duke University, with study overseas at Oxford University’s New College, and then completed a PhD in Computer Science. At the Department of Energy, then as faculty at the University of Chicago, The Rockefeller University, and now UCSD, she has sought to apply AI technologies to study and solve problems in biological systems and genomics, including genetic/genomics response to climate change stresses. In 2018, Terry was elected to the Del Mar City Council. In her active dual career as a scientist and as a local elected official, she strives to bring science and policy together to address problems at the local political level with particular emphasis on challenges facing California’s coastal cities and jurisdictions. She chaired Del Mar’s Sea Level Rise Technical Advisory Committee (2014-2018). Under her leadership, Del Mar’s Sea Level Rise Adaptation Plan was developed to address vulnerabilities and protect against beach loss, and adopted into the Community (General) Plan. TG’s contributions to this Report reflect her own views and do not speak for the City.

June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 61 Camilla Rang, PhD
Camilla is a senior researcher at the department of Ecology, Behavior and Evolution (EBE) at the University of California, San Diego (UCSD). Her research focuses on the evolution and origin of aging in single cells organisms. She earned her PhD from Göteborg University, Sweden, studying the impact of microbiome on single cell bacteria in the intestine, and her post doc from the Center of Vaccine Development, University of Maryland, Baltimore. When joining UCSD 23 years ago, Camilla and her family settled in Del Mar, where she since has been an active and involved resident.

Laura DeMarco
Laura is a 34-year Del Mar resident and experienced fiduciary and investment management executive. As a senior partner, she contributed to the successful launch and development of two investment firms, including a global asset manager which grew to over $40B in assets under management. Laura uses her research and analytical skills to serve on investment committees and advise large public and corporate pension funds, insurance companies, financial institutions, endowments, foundations, Taft-Hartley plans and their investment consultants. She graduated from the University of San Diego and has over 30 years of institutional investment experience.

John Stanley, PE
John is a Del Mar Heights resident and licensed professional engineer with over 25 years of experience. A major area of his expertise is evaluating materials, stresses, and operational stability of machinery and aircraft in his role with the Department of Defense and as a design and engineering consultant. He is also a private pilot who has built experimental aircraft. Stanley earned his degree in mechanical engineering from San Diego State University.

Computer Visual Simulations © 2021, Payson R Stevens
Google Earth attribution:

Google Earth Pro 7.3.4.8248, (2021) Del Mar Bluffs at 7th St. 32°57'2.40"N, 117°15'56.31"W, elevation between 8’- 79’ above sea level. 3D Buildings, Terrain, Borders and Labels data layers. Data SIO, NOAA, U.S. Navy, GEBCO. [Online] Available at https://www.google.com/earth/versions/ [Accessed 27 October 2021] Visualization Coordinates
Ex Seawall 2.3 32°57'2.40"N, 117°15'56.31"W
Ex Seawall 2.2 32°57'18.06"N 117°16'2.26"W
Ex Seawall 2.1 32°57'25.19"N 117°16'3.86"W
Seawall 32°57'29.65"N 117°16'4.91"W
Visualization Notes:

Fig 2: Depicted Seawalls are 3 Meters above ground (9.84’) which does not take sand into consideration and should be considered a rough approximation. Due to limitations of software the altitude of the wall can only be adjusted in 1 Meter (3.28’) increments. 2 Meters (6.56’), while technically the closet to 8’; seemed too low visually as the bottom portion of the wall does “sink” or “clip” into the ground in the 3D model.

June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 62 Natural Coastal Bluff Top Trail For All To Enjoy
(photo, Karl Willert)
Protect, preserve, and respect
the Del Mar Bluffs and Beaches
now and forever.

June 6, 2022 Item 13

Proposed NCTD and SANDAG Engineering
Impacts on the Del Mar Bluffs & Beach
Scientific Questions and Concerns
June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 3 OVERVIEW
The Del Mar Bluffs are the last remaining stretch of 1.7 miles of natural terrain trails in San Diego North County. The Bluff and beaches have had continuous community access for over a century.

The 20 to 30-year engineering plan proposed by the San Diego Association of Governments (SANDAG) and the North County Transit District (NCTD) will irrevocably damage the Bluff and beach and also deny access to the wide community of the public who have used them for 100 years.

This Report is addressed to the California Coastal Commission and concerned governmental, nongovernmental, and citizen groups who have the means to question and challenge the engineering plans and ultimately to protect and preserve the natural Bluffs with the open beaches below for future generations.

The Report raises critical scientific and engineering questions related to the on-going and proposed engineering of the Del Mar Bluffs and beaches. Further, the Report will educate and inform stakeholders who question the engineering plans.

Appendices provide expanded material on the questions and issues that need review by Coastal Commission staff and engineers, and by concerned public and private groups.

Our Objectives
Protect and Preserve the Del Mar Bluffs & Beach
• Visualize:
o Simulations of what is planned
o Engineering underway now
• Raise Unanswered Scientific & Engineering Questions
• Define Critical Issues Ensuring they are Objectively Addressed We Call on the Coastal Commission to
• Ensure that SANDAG and NCTD Proposed Plans Are Subject to an Environmental Impact Report (EIR) by objective and expert engineers and scientists; and • Ensure that the California Coastal Commission (CCC) legal mandate to protect the California Coastline is not hampered or superseded by legal maneuvers with the Surface Transportation Board.

June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 4 Urgent Action Required WITHOUT Excessive Measures
Del Mar, SANDAG and NCTD have a multi-faceted problem, 20 years in the making. Why should the lack of adequate progress relocating the railroad result in the destruction of the Del Mar Bluff and its beaches in San Diego’s North County?
The Bluff is fragile and will continue to erode and collapse. It is understood and accepted that some degree of protection is needed to ensure the safety of the railway line that currently runs the 1.7 miles of the Bluff. Nevertheless, the Bluff offers multiple benefits to the community as one of the San Diego region’s last remaining natural, accessible coastal bluff with trails above and beach below. Irreversible changes must be avoided.

The consequences of planned structures will deface the bluffs with armoring and grading, bury beaches and bluff toes behind seawalls, and deplete natural sand replenishment. This Report strongly questions the 20 to 30-year engineering plans as excessive and unproven.

Alternatively:

Relocate now. The railway line runs through Del Mar as a single track on top of the fragile bluff.

The need for relocation has been recognized for over twenty years. Sea level rise and climate change have sped up the urgency. The tracks must be moved within the next 7 years without further delay.

Minimize interim engineering. In the interim, the extent of the proposed engineering requires thorough, objective scrutiny by independent engineers and coastal bluff and beach processes scientists to ensure minimal long-term impact on the Bluff with appropriate mitigation.

Requests to all responsible agencies and individuals:
• Ensure enforcement of Coastal Commission legal mandates • Require an Environmental Impact Report from SANDAG and NCTD • Minimize engineering to save the natural coastal Bluff, beaches, and access
• Relocate railroad tracks no later than 7+ years
• Commit funds to reverse the engineering impacts after relocation June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 5 WHAT IS PLANNED?
SANDAG leads a project to impose environmentally destructive engineering structures along the entire 1.7-mile coastal Bluff top, face, and toe and the beach below that will:
• Armor the entire Bluff with long continuous seawalls on the beach that will eliminate the natural chiseled contours of the Bluff toe and obscure flow of beach sand; • Bury beaches behind the seawalls with in-fill dirt on top of beach sand and Bluff toes; • Destroy bluff faces extensively with grading and compaction that will erase the existing natural bluff geologic features;
• Construct long retaining walls at the coastal bluff-top edge, west of tracks; and • Decapitate completely the upper ~25% of the highest west-facing Bluff face.

NCTD leads a separate project to install fencing on the Bluff tops for the full 1.7 miles.

On October 15, 2021, Del Mar Council members and staff walked the entire length of the SANDAG bluff project together with SANDAG and NCTD engineering staff and one NCTD Board member.

At that time, SANDAG staff indicated the engineering consultants had been directed to plan for another 20 years of train operations atop the fragile, sensitive coastal Bluff (Figure C-3, Appendix C).

COMMUNITY RESPONSE
A Citizens’ Petition submitted to the California Coastal Commission, October 13, 2021, clearly states the community’s concerns regarding the unique qualities of the Del Mar Bluffs and beaches that draw tens of thousands of visitors to walk, swim, surf, and enjoy (Appendix D). The Petition was uploaded to change.org to collect signatures electronically.

Many environmental impact concerns and questions about the fencing project are addressed in the Petition. Further questions were raised by independent third-party engineering experts from Atlas Technical Consultants, LLC, contracted by the City of Del Mar (Appendix B).

Residents of Del Mar, other San Diego communities, and from afar, have presented objections to the excessive engineering plans of SANDAG and NCTD in public meetings before the Del Mar City Council, the California Coastal Commission (CCC), North County Transit District (NCTD), and the San Diego Association of Governments (SANDAG) (See verbal and written Public Comments at meetings of these bodies during the week of Oct. 18, 2021).

This Report poses critical, unanswered questions to ensure they are objectively addressed now.

June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 6 OVERSIGHT IS LACKING
The geotechnical stabilization plans offered by SANDAG and NCTD are unproven, excessive, and plan for 20 to 30 more years of bluff top railroad operation. The community demands a shorter timeline in which the railroad tracks go elsewhere, and the natural Bluff beauty remains.

The community realizes that some preventive engineering is required as soon as possible to protect the tracks and trains before they are relocated. However, the community demands that current engineering in process and planned engineering receive the full scrutiny required by the California Coastal Act. Irreversible changes must be avoided.

NCTD’s approach to fencing the bluffs has disregarded the community and the importance of the natural coastal bluff and beach environment. Their reliance on a cursory geological opinion to justify massive drilling, imposition of concrete and fencing on the Bluff serves as a stark lesson that the Coastal Commission must not rely on the assurances of either NCTD nor SANDAG nor their consultants that their proposed sweeping redesign of the Bluff are the least most destructive and necessary to accomplish legitimate goals.

Dramatic, permanent changes are planned and underway without environmental review. They are a blow to the environment, armoring the Bluff with ugly concrete structures and seawalls creating a gauntlet to beach access: a direct violation of the Coastal Commission’s legal authority and mandate.

THE BOTTOM LINE
Why do a 20 to 30-year project when the track relocation is expected within 10 years? Why destroy the Bluff and beaches when less destructive engineering is possible to bolster the Bluff until the railway is moved? The Coastal Commission has the legal
mandate and singular mission to
protect our precious California coast
June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 7 A Brief Visual Tour in Five Images

1. Proposed Engineering Ignores Coastal Protections
Visualization looking north along the Bluff from 11th St north to Coast Blvd.

IMPACTS:
• Grading and terracing will replace natural Bluff contours with industrial faces. • All red shaded areas will turn into artificial graded slopes. • High seawalls (purple) will obscure the base of the Bluff along the beach.

See Appendix A for more visualizations.

June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 8 2. Continuous Seawalls Restrict Beach Access & Sand Renewal Visualization looking south between 15th and 11th Streets.

IMPACTS:
• A long high seawall (purple) will block natural coves and bluff/beach features. • Long seawalls 8 to 10 feet high will separate beachgoers from the Bluff’s lively life. • Bluff environments for small animals, wild plants, sea grasses, nesting birds, native frogs, and their ecosystem will be buried and obstructed.
• A walk along the beach will change completely - the Bluff will be caged behind a vertical wall.

See Appendix A for more visualizations.

SANDAG’s plans ignore zoning
ordinances certified by the Coastal
Commission that limit protective
structures west of the middle of the
railroad track
June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 9 3. Natural Beauty Will Be Irreversibly Destroyed
Natural Bluff from 11th to 8th St is slated to be decapitated. (photo, Terry Gaasterland) IMPACTS:
• SANDAG plans will remove the top 20 to 25 feet of tall natural Bluff. • Bluff crevices where birds nest and small animals live will be gone forever. • Bluff material for sand replenishment will be eliminated.

June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 10 4. Engineering Already Underway
SANDAG’s Terracing At South End of Del Mar Woods. (photo, Terry Gaasterland) With no environmenal review or public input whatsoever, SANDAG commenced with a small emergency repair that has grown into an outsized insult on the natural bluff face.

June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 11 5. Armoring The Coast – Natural Beauty vs. Concrete Hardening BEFORE: Coastal Bluff Top Trail below Del Mar Woods. (photo, Michael Keenan) AFTER: Bluff Top Trail - Concrete drainage, natural flora/terrain scraped. (Photo, Payson R. Stevens)
June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 12 CRITICAL QUESTIONS
The Coastal Commission needs to require that these critical questions about impacts be answered by SANDAG and NCTD before moving forward. Without an EIR, the consequences of the engineering can never be fully understood and addressed.

1. What is the time horizon for the engineering before the railway is moved as that should determine the degree of armoring needed? What’s the difference and impacts between a 20 to 30-year engineering plan versus a 10-year plan?

2. How will grading and in-fill be managed and minimized?

3. Can the project be reframed to place localized seawalls in high-risk locations? The risk of bluff slide and erosion is not the same along the entire Bluff. Collapses are punctuated, local events.

4. How will imminent sea level rise affect the beaches and proposed seawalls?

5. Are funds set aside to remove seawalls after railroad relocation.

6. Does SANDAG have jurisdiction to construct seawalls on the beach and bury coves behind them?

7. Have agencies with jurisdiction over the beach been included in the planning? For example, State Parks, the State Lands Commission, and the City of Del Mar. The southernmost planned seawall is on the Torrey Pines State Beach

8. Has SANDAG studied the impacts of the seawalls on wave energy dissipation patterns and erosion dynamics? How significant will the resulting active beach erosion be?

9. What serious and committed efforts are underway to relocate railroad in 7 to 10 years?

10. Will the proposed engineering plans be made consistent with the planned train relocation? Appendix C provides expanded details for each Critical Question.

At this time no Environmental
Impact Report (EIR) has been
prepared for
either agency’s project.

June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 13 SUMMARY OF SCIENTIFIC QUESTIONS AND ANALYSIS NEEDED
Geotechnical Impacts
Expert analysis of geotechnical impacts of the SANDAG’s proposed engineered structures are clearly lacking and must be done. The City of Del Mar contracted an independent review of NCTD’s geotechnical report by Leighton Consulting, Inc (2021) on their 1.7 miles of fencing plans.

The independent review found multiple, serious deficiencies. Specifically, the critique of the Leighton report by third-party expert consultant Atlas Technical Consulting, LLC, noted analysis, tests, and measurements that were missing from the Leighton report.

The Atlas observations on needed geotechnical analysis pertain not only to the NCTD fencing but more generally to any engineering project on the fragile coastal Bluff. The following needs for analysis of geotechnical impacts apply equally to the SANDAG engineering. See Appendix B for these fundamental geotechnical questions that must be answered.

Details for the above scientific concerns can be found in Appendix C.

Pressing questions and impacts must be addressed and require SANDAG’s public response.

Urgent Analysis is Lacking in Key Scientific Areas:
• Rain and irrigation subsurface Bluff penetration
• Latest technology for assessing Bluff geology
• Beach erosion effects from seawall construction along Bluff toe • Sea level rise with wave energy against sea walls
• Identification of flora and fauna of Del Mar Bluff and beaches • Vibration effects on coastal Bluff west of tracks
• Seismic risks and the Rose Canyon Fault
• Other adverse consequences (make specific – TG)
June 6, 2022 Item 13
Proposed NCTD and SANDAG Engineering Impacts on Del Mar Bluffs & Beach • Scientific Questions & Concerns • November 8, 2021 14 REPORT DISTRIBUTION LIST
Coastal Commissioners
Coastal Commission Executive Staff
San Diego County Board of Supervisors
Copied to:

State Assembly Representatives and Senators for San Diego Region Federal Congress Members for San Diego Region
Council Members, Mayors and City Managers of San Diego Coastal Cities California Department of Transportation
California Department of Parks and Recreation
Sierra Club
Surfrider Foundation
San Diego Habitat Conservancy
Torrey Pines Conservancy
June 6, 2022 Item 13
Coarse Sediment Yields from Seacliff Erosion in the
Oceanside Littoral Cell
Adam P. Young{, Jessica H. Raymond{, John Sorenson{, Elizabeth A. Johnstone{, Neal W.

Driscoll{
, Reinhard E. Flick{, and Robert T. Guza{
{
Integrative Oceanography Division
Scripps Institution of Oceanography
University of California
San Diego, 9500 Gilman Drive
La Jolla, CA 92093-0209, U.S.A.
[email protected]
{
Geosciences Research Division
Scripps Institution of Oceanography

ABSTRACT
YOUNG, A.P.; RAYMOND, J.H.; SORENSON, J.; JOHNSTONE, E.A.; DRISCOLL, N.W.; FLICK, R.E., and GUZA, R.T., 2010. Coarse sediment yields from seacliff erosion in the Oceanside Littoral Cell. Journal of Coastal Research, 26(3), 580–585. West Palm Beach (Florida), ISSN 0749-0208.

The coarse sediment fraction of geologic formations exposed in 42 km of southern California seacliffs in the Oceanside Littoral Cell was estimated using more than 400 samples. An impulse laser, oblique photographs, and coastal maps were used to define thickness and alongshore extent of the geologic units exposed in the seacliffs. The coarse sediment (defined as diameter . 0.06 mm) fraction in each geologic unit was estimated by sieving. About 80% of the exposed cliff face is coarse and can contribute to beach building. Finer cliff sediments are transported offshore by waves and currents.

Although there are some differences, the observed 80% coarse fraction is generally consistent with previous estimates based on an order of magnitude fewer samples. Coastal development has largely eliminated about 40% of seacliffs in the Oceanside Littoral Cell as potential beach sand sources. For the remaining seacliffs, 1 cm of average cliff retreat yields 10,000 m3 of potential beach-building material.

ADDITIONAL INDEX WORDS: Coastal erosion, cliffs, southern California, sediment budget.

INTRODUCTION
Southern California beaches are important economic, cultural, and recreational resources. Beaches also provide a natural buffer against coastal erosion that threatens coastal infrastructure throughout the region. An understanding of littoral budgets and processes is necessary for proper coastal management. Natural beach sediment inputs in California include rivers, seacliffs, gullies, and terrace surface erosion. In general, rivers contribute the majority of sand to California beaches (Best and Griggs, 1991; Bowen and Inman, 1966; Knur and Kim, 1999). River contributions of sand in southern California tend to be concentrated around relatively rare large-flow events associated with winters of especially high or concentrated rainfall. Recent research (Haas, 2005; Young and Ashford, 2006a) suggests seacliff erosion sometimes also supplies a significant amount of sediment to beaches in the Oceanside Littoral Cell.

The key variables in estimating the seacliff beach-sediment contribution include the rate of cliff erosion and the amount of coarse-grained sediment within the seacliffs that will potentially remain in the nearshore littoral system. While numerous studies have evaluated cliff erosion and retreat rates within the Oceanside Littoral Cell (Benumof and Griggs, 1999; Benumof et al., 2000; Emery, 1941; Emery and Kuhn, 1980; Everts, 1990; Hapke and Reid, 2007; Kuhn and Shepard, 1980, 1984; Lee, 1980; Moore, Benumof, and Griggs, 1999; Robinson, 1988; Runyan and Griggs, 2003; Vaughan, 1932; Young and Ashford, 2006a, 2006b, 2007, 2008), little work has evaluated the cliff grain size composition. Here, extensive new cliff sampling and grain size analysis are used to better determine the coarse fraction of cliff sediments in the Oceanside Littoral Cell.

STUDY AREA
The Oceanside Littoral Cell, located in northern San Diego and southern Orange Counties (Figure 1), spans 85 km of coastline from Dana Point to La Jolla (Inman and Frautschy, 1966). The cell is characterized by narrow sand and sometimes cobble beaches backed by seacliffs cut into uplifted marine terraces. Seacliffs comprise 80% of the littoral cell, with occasional alternating lowlands at coastal river mouths and lagoons. The majority of the Oceanside Littoral Cell contains residential, commercial, and recreational development on the cliff top, with the exceptions of the Camp Pendleton Military Reservation and San Onofre State Park. The cliffs are subject to both marine and subaerial erosion.

Urbanization and development of the region have altered the coastline (Flick, 1993; Griggs, Patsch, and Savoy, 2005; Inman, 1976), including a reduction in natural beach sediment supply caused by river damming (Willis and Griggs, 2003) and coastal armoring (Runyan and Griggs, 2003; Young and Ashford,
2006b). In the Oceanside Littoral Cell, damming has reduced DOI: 10.2112/08-1179.1 received 31 December 2008; accepted in revision 26 March 2009.

Journal of Coastal Research 26 3 580–585 West Palm Beach, Florida May 2010 June 6, 2022 Item 13
the river sediment input by approximately 50% (Flick, 1993, 1994; Willis and Griggs, 2003), while coastal armoring and segregation have largely eliminated a significant portion of seacliffs as a potential sediment source. In addition to damming of the watershed, much of the adjacent watershed has been urbanized, and together these areas comprise 60% (40%
dammed and 20% urbanized and not dammed; Figure 1) of
the adjacent watershed. Warrick and Rubin (2007) suggest urbanization in southern California has significantly changed fluvial sediment loads and present-day loads may be substantially overestimated. The deficit in natural beach sediment supply in the Oceanside Littoral Cell has been counteracted by numerous beach replenishment projects since the 1940s with more than 15 million m3 of sand (Flick, 2005). Despite these Figure 1. (A) Map of the Oceanside Littoral Cell and the adjacent watersheds that have been altered by dams (pink areas) and urbanization (black areas). In total, the damming and urbanization has resulted in a 60% reduction of the sediment-producing land area. (B) Map of the Oceanside Littoral Cell and the seacliff sections used in this study. Pink areas correspond to seacliffs that are significantly armored or separated from the littoral system by roads and railways, and green areas represent seacliffs without significant defenses. In total, 42% of the seacliffs are significantly protected and no longer contribute significant amounts of sediment to the littoral system.

Seacliff Sediment Yields 581
Journal of Coastal Research, Vol. 26, No. 3, 2010
June 6, 2022 Item 13
beach replenishment projects, waves continue to erode the seacliffs, threatening cliff top infrastructure and public safety.

The seacliffs are usually between 25 and 33 m high but reach over 100 m in Torrey Pines. The cliffs are generally composed of two geologic units: (1) a lower unit of lithified Eocene, Miocene, or Pliocene mudstone, shale, sandstone, and siltstone, and (2) an upper unit of unlithified Pleistocene terrace deposits (Kennedy, 1975). The geologic conditions (e.g., cliff resistance to erosion) vary alongshore at a range of scales, which contributes to the alongshore variation of cliff erosion rates and coarse sand content. Estimated long-term cliff retreat rates vary widely (between 2 and 170 cm/y) for different time periods and cliff sections in the Oceanside Littoral Cell (Benumof et al., 2000; Everts, 1990; Hapke and Reid, 2007; Moore, Benumof, and Griggs, 1999).

The cliffs in northern Carlsbad, Oceanside, San Clemente, and Dana Point (a combined length of ,24 km) are either developed or removed from wave action by coastal roads or railways and were not evaluated in this study. The remaining 42 km of cliffs were divided into nine sections, based on general lithology and lagoon incisions (Figure 1). Approximately 2 km of scattered sections of unprotected cliffs (Figure 1) were not evaluated.

BACKGROUND
After a cliff failure, wave action disaggregates the talus and mobilizes the fine-grained sediments that are transported offshore. In contrast, coarse sediments are typically retained in the littoral zone and supply new beach-building material. The grain size threshold nominally separating these depositional environments is known as the littoral cutoff diameter (Best and Griggs, 1991; Hicks, 1985; Hicks and Inman, 1987; Limber, Patsch, and Griggs, 2008). Best and Griggs (1991, p. 38) define the littoral cutoff diameter as a grain size threshold below which sediment ‘‘will not remain within the active zone of littoral transport in any appreciable quantity’’; however, there is currently no uniform method to sample and calculate this threshold (Limber, Patsch, and Griggs, 2008). For the Oceanside Littoral Cell, Everts (1990) used 81 samples (USACOELAD, 1984b) and found approximately 95% of the sediments in the littoral zone were larger than 0.063 mm, while Runyan and Griggs (2003) used 10 samples and found 99% of the sediments were larger than 0.088 mm. The transition from offshore transport to beach deposition is gradual, and further research could better define the effect of grain size on sediment retention in the Oceanside Littoral Cell. We used 0.063 mm as the littoral cutoff diameter, the value obtained with the larger sample size, to estimate the amount of beach-sized sand in the cliffs.

The percentages of coarse seacliff sediments were previously estimated (Table 1) for areas of the Oceanside Littoral Cell by the U.S. Army Corp of Engineers, Los Angeles District
(USACOE-LAD, 1984a), Robinson (1988), Everts (1990), the California Department of Boating & Waterways and the State Coastal Conservancy (CDBW and SCC, 2002), and Runyan and Griggs (2003). Unfortunately, these estimates were based on a small number of samples at a few locations and in some cases were extrapolated over long distances over which the cliff composition changes. This study builds upon the previous research to provide a more detailed alongshore description of coarse sediments exposed along the cliffs, using extensive cliff sampling, sieve analysis, and detailed geologic mapping.

METHODS
Geolocated cliff samples were collected and analyzed for coarse-grain content (diameter . 0.063 mm) by sieving into two size classes (diameter $ 0.063 mm and diameter , 0.063 mm).

The extent and thickness of the general geologic units were mapped. The average amount of coarse sediment (PCoarse) for a given alongshore location was then estimated using a geologic layer thickness approach (Runyan and Griggs, 2003):

PCoarse ~P1(T1=Hc)zP2(T2=Hc)
The percentage of coarse material (lower unit 5 P1, upper unit 5 P2) is weighted by the relative vertical thickness of each geologic unit (lower unit 5 T1/Hc, upper unit 5 T2/Hc), where Tn and Hc are the unit thickness and the total cliff height, respectively (Figure 2). At a few locations in Solana Beach and Leucadia, where major seawalls completely cover the lower geologic unit (T1), the first term in the equation was zero. A third term in the equation was added for locations where a gradual transition in the lower geologic units creates two overlapping lower geologic units.

The alongshore cliff height was measured using a digital elevation model derived from airborne light detection and ranging data. The extent and thickness of the geologic units were mapped in the field using an impulse laser (Laser
Technology), oblique photographs (California Coastal Records Project, 2008; Terracosta Consulting Group, 2001), and coastal maps (Flick, 1994; Kennedy, 1975, 2001; Kennedy and Tan, 2007; Tan, 2001; Tan and Kennedy, 2006).

Previous geologic maps and studies (Berggreen, 1979; Ehlig, 1977; Flick, 1994; Kennedy, 2001; Kennedy and Tan, 2007; Tan, 2001) are inconsistent in their interpretation of the Table 1. Summary of the percentage of coarse sediments within the seacliffs.

USACOELAD (1984a)Robinson
(1988)
Everts
(1990)
CDBW and
SCC (2002),
Runyan and
Griggs (2003)
This
Study
Number of
samples
* 26 { 13 441
Number of sites * 9 { 9 295
San Onofre 80 72 60 52 62
Camp Pendleton
north
80 54 60 52 72
Camp Pendleton
south
80 { 60 52 67
Carlsbad 80 { 80 55 90
Leucadia 80 { 65 53 94
Cardiff 80 { 65 53 81
Solana Beach 75 { 65 53 93
Del Mar 75 { 65 53 61
Torrey Pines 75 42 65 52 78
* Information not given, values probably estimated without sampling. { Sections not evaluated.
{ No new samples evaluated, estimates based on USACOE-LAD (1984a) and Robinson (1988).
582 Young et al.

Journal of Coastal Research, Vol. 26, No. 3, 2010
June 6, 2022 Item 13
geology in southern San Onofre and northern Camp Pendleton, where the lower unit has been variously mapped either as the San Mateo or as sandy facies of the Monterey Formation. Here, the lower unit was delineated into regions based on the sample sand content and labeled as geologic units A and B (Figure 3).

Cliff sample locations were spaced (exceptions are noted later) approximately 100 to 200 m apart, and a 10- to 500-g (average an ,200-g) sample was acquired from each geologic unit, yielding 441 samples. Time limits imposed by access restrictions in Camp Pendleton prevented dense sampling, and the between-sample distance in this section averaged approximately 500 m. The high cliffs of Torrey Pines (.90 m) prevented sample collection from the upper geologic units.

Therefore, samples of talus deposits taken at the Torrey Pines cliff base were assumed representative of the overall cliff.

Each sample was oven dried, weighed, disaggregated, and wet sieved (excluding Torrey Pines samples, which were dry sieved) with a 0.063-mm sieve to remove the fine material. The samples were then redried and reweighed to determine the percent weight of coarse material. Next, the samples were averaged by geologic unit and cliff section. This geologic unit average, and fine-scale maps of cliff height and unit thickness, were used in the previously given equation to determine PCoarse at 3-m alongshore intervals.

RESULTS
The PCoarse percentage ranged from 12 to 97%, with an
overall average (weighted by section length) of 77%. Alongshore variation was partly caused by differences in the composition of the terrace deposits that make up the majority of the cliff in most areas. Because of differences in the original depositional environment, terrace deposits further south contain less-fine-grained sediments. These sediments (PCoarse . 90%) were deposited in a nearshore environment, and wave action had already winnowed fine sediments, resulting in Figure 2. Typical seacliffs include a lower unit of lithified Eocene, Miocene, or Pliocene deposits and a thicker upper unit of unlithified Pleistocene terrace deposits (after Runyan and Griggs, 2003). The notation refers to variables used in the equation given in the main text.

Figure 3. (Upper) Alongshore variation of percentage of seacliff sand content (sediment coarser than 0.063 mm). (Center) Percentage of seacliff sand content by geologic unit. (Bottom) General geologic units of the study area, and table of section and geologic unit statistics.

Seacliff Sediment Yields 583
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relatively high PCoarse values in the southern half of the littoral cell, notably in Solana Beach, Cardiff, Leucadia, and Carlsbad (81–91%; Table 1). In contrast, farther north, the fine sediments are still present in the terrace deposits of nonmarine alluvial fans (PCoarse < 70%).

Many localized, abrupt changes of PCoarse in San Onofre and Camp Pendleton, and at one location in Solana Beach, occur where the upper terrace deposits are absent mainly because of gullying. Gully erosion of the upper terrace deposits causes PCoarse of the entire cliff to equal PCoarse of the lower geologic unit. For example, in areas where the Monterey Formation outcrops in the lower cliff, the difference between the PCoarse of the upper (65–71%) and that of the lower (12–17%) geologic units is large, resulting in abrupt alongshore changes in PCoarse.

The average height of the 42 km of cliffs (31 m) and the average PCoarse (77%) equate to a seacliff coarse sediment yield of 10,000 m3 per centimeter of regionwide cliff retreat.

DISCUSSION AND SUMMARY
The present PCoarse estimates are generally similar to those of previous studies (Table 1), with some significant differences in a few particular section comparisons. For example, PCoarse for Torrey Pines is almost double the value in Robinson (1988) but similar to that in USACOE-LAD (1984a). Seacliff PCoarse amounts found here for Carlsbad, Leucadia, Cardiff, Solana Beach, and Torrey Pines were slightly higher than those found in all previous studies. Differences among studies are likely caused by the location and the number of samples analyzed.

The present results generally agree well with at least one of the previous studies and refine and synthesize earlier estimates.

Although the average overall PCoarse of 77% varies only slightly compared to the 79% (USACOE-LAD, 1984a), 65%
(Everts, 1990), and 53% (Runyan and Griggs, 2003) found in previous studies, the rates of cliff retreat and erosion can vary by an order of magnitude for the same locale (Everts, 1990), introducing uncertainty into estimates of the seacliff beachsediment contributions. Even when retreat rates from previous studies (Benumof and Griggs, 1999; Benumof et al., 2000; Everts, 1990; Hapke and Reid, 2007; Moore, Benumof, and Griggs, 1999; Runyan and Griggs, 2003) are averaged
(weighted average by section length), the long-term retreat rates of the entire littoral cell range from 5 to 20 cm/y. (Note that Benumof and Griggs, 1999; Benumof et al., 2000; and Moore, Benumof, and Griggs, 1999, do not provide retreat rates for cliffs north of Oceanside.) Large differences in the retreat rates are caused by episodic cliff retreat, along with endpoint retreat rate estimates, data sources used, time frame of study, retreat measurement method, and changing amounts of cliff protection. Therefore, although accurate estimates of coarse sediment yield require accurate PCoarse, as provided here, the uncertainty in erosion and retreat rates remains relatively large and introduces more variation in seacliff beach-sediment contributions compared to PCoarse.

Approximately 12% (5 km, all located south of Oceanside) of the cliffs evaluated for sand content are substantially protected with large revetments and seawalls. Additional small-scale protective devices exist throughout the study area. Although reducing the erosion rate, they do not eliminate all erosional processes (e.g., subaerial erosion by rain; Young and Ashford, 2006b). In total, 42% (29 of 69 km) of the seacliffs in the Oceanside Littoral Cell are currently either substantially armored or isolated from the littoral system, removed from wave action, and probably no longer contributing significant amounts of sediment to the beach.

ACKNOWLEDGMENTS
A.P.Y. received postdoctoral scholar support from the
CDBW Oceanography Program. N.W.D. and E.A.J. received
support from California SeaGrant. R.T.G. received support from the U.S. Army Corps of Engineers and CDBW.

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Comparison of short-term seacliff retreat measurement methods in Del Mar, California
Adam P. Young a,
⁎, R.E. Flick a
, R. Gutierrez b, R.T. Guza a
a Integrative Oceanography Division, Scripps Institution of Oceanography, University of California San Diego, 9500 Gilman Dr., La Jolla, CA, 92093-0209, USA b The University of Texas at Austin, 1 University Station, Austin, TX, 78712, USA article info abstract
Article history:

Received 31 March 2009
Received in revised form 23 June 2009
Accepted 23 June 2009
Available online 8 July 2009
Keywords:

Coastal erosion
Seacliff retreat
Southern California
Change detection
LiDAR
Seacliff retreat has been variously characterized as the recession rate of the cliff top, of the cliff base, and as the bulk recession rate based on volumetric changes of the entire cliff face. Here, these measures of retreat are compared using nine semi-annual airborne LiDAR (Light Detection And Ranging) surveys of southern California seacliffs. Changes in the cliff base location (where the steeply sloping cliff face intersects the beach) include cliff retreat owing to basal erosion, but also reflect changes in beach sand level and basal talus deposits. Averaged over the 2.5 km alongshore study span, the cliff base actually prograded seaward about 12 cm during the 4-year study. Cliff top change was dominated by few, relatively large (several meters) localized retreats. Cliff face changes, that include failures and deposits anywhere on the cliff profile, had a relatively small mean magnitude compared to cliff top changes and were more widely distributed alongshore. However, the similar alongshore averaged, cumulative cliff top and net bulk cliff face end-point retreat (14 and 19 cm, respectively) suggest that mean cumulative cliff top retreat can potentially be a viable surrogate for mean net cumulative cliff-wide erosion (and vice versa) over relatively short time periods. Cliff face erosion occurred repeatedly at some locations, confirming the presence of seacliff erosion hot-spots during the study period.
© 2009 Elsevier B.V. All rights reserved.

1. Introduction
Seacliff retreat, important to coastal management, is often estimated using the recession of the cliff top or cliff base obtained from aerial photographs, topographic maps, or in situ surveys (e.g.

Jones and Williams, 1991; Wilcock et al., 1998; Benumof and Griggs, 1999; Moore et al., 1999; Budetta et al., 2000; Hapke and Richmond, 2002; Pierre and Lahousse, 2006; Dornbusch et al., 2008; Greenwood and Orford, 2008). Recently, three-dimensional high resolution maps derived from LiDAR have been used to estimate the cliff face bulk retreat, defined as the volumetric change (measured by differencing successive digital elevation models) divided by the cliff height and the alongshore width of a cliff section (Young and Ashford, 2006a,b).

Cliff top, base, and face change estimates can differ significantly over short time periods. For example, wave action can cause cliff base retreat, but no cliff top change (Fig. 1A). Mid-cliff face erosion can occur without changes to the cliff top or base (Fig. 1B). Alternatively, a cliff top failure may result in significant cliff top recession and no change at the cliff base if the talus is removed by wave action prior to subsequent data collection (Fig. 1C). When talus deposits are incompletely removed between surveys, the cliff base appears to accrete (Fig. 1D, E). Additionally, the cliff base location changes when the beach sand level at the cliff base changes (Fig. 1F, an increase in beach sand level causes retreat of the estimated cliff base location).

Although these estimates will converge over long time periods, short-term, seasonal estimates provide insight into cliff retreat processes (e.g. the relative importance of higher than usual rainfall or waves). Here, changes in the cliff top, cliff base, and cliff face, estimated using nine semi-annual airborne LiDAR surveys spanning four years are compared.

2. Study area
The studied 2.5 km reach of seacliffs in Del Mar, California (Fig. 2B), on average 18 m high with approximately 45° slope, are cut into uplifted marine terraces. The lower cliff consists of the Del Mar Formation, an Eocene sedimentary deposit composed of sandy claystone interbedded with coarse-grained sandstone (Kennedy, 1975). Near the middle of the study area, the Del Mar Formation is overlain by permeable sandy Pleistocene terrace deposits (Fig. 2C). The Del Mar Formation is relatively impermeable, resulting in perched groundwater and sapping at the interface with terrace deposits. The cliff face experiences weathering, desiccation, sheet erosion, and rilling, while the cliff base is subject to wave action. Typical beach width ranges from 30 to 70 m, and fluctuates seasonally with wider beaches in summer. During winter, the eroded beach permits direct wave attack at the cliff base when elevated tides coincide with large Geomorphology 112 (2009) 318–323
⁎ Corresponding author. Tel.: +1 858 822 3378; fax: +1 858 534 0300.

E-mail address: [email protected] (A.P. Young).
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j o u r n a l h om e p a g e : www. e l s ev i e r. c om / l o c a t e / g e om o r p h June 6, 2022 Item 13
Decadal-scale coastal cliff retreat in southern and central California Adam P. Young
Scripps Institution of Oceanography, University of California San Diego, 9500 Gilman Dr., La Jolla, CA 92093-0209, USA article info abstract
Article history:

Received 12 May 2017
Received in revised form 6 October 2017
Accepted 13 October 2017
Available online 19 October 2017
Airborne LiDAR data collected in 1998 and 2009–2010 were used to measure coastal cliff erosion and retreat between the Mexico/California border and Bodega Head, California. Cliff erosion was detected along 44% of the 595 km of shoreline evaluated, while the remaining cliffs were relatively stable. The mean cliff top retreat rate was 0.12 m/yr, while mean retreat averaged over the entire cliff face was 0.04 m/yr. The maximum cliff top and face retreat rates were 4.2 and 3.8 m/yr, respectively. Historical (~1930s to 1998) and recent retreat rates were significantly inversely correlated for areas with large historical or recent cliff retreat, such that locations with elevated historical retreat had low levels of recent retreat and locations with elevated recent retreat were preceded by low rates of historical retreat. The strength of this inverse correlation increased with cliff change magnitudes up to r2 of 0.91 for cliff top retreat rates N2.9 m/yr. Mean recent retreat rates were 52-83% lower than mean historical retreat rates. Although beaches can protect cliffs against wave-driven erosion, cliffs fronted by beaches retreated 49% more than cliffs without beaches. On average, unarmored cliff faces retreated 0.05 m/yr between 1998 and 2009–2010, about three times faster than artificially armored cliffs. Alongshore metrics of wave-cliff impact, precipitation, and cliff hardness were generally not well correlated with recent cliff changes.

A cliff hazard metric is used to detect cliff steepening and areas prone to future cliff top failures. © 2017 Elsevier B.V. All rights reserved.

Keywords:

Coastal cliffs
LiDAR
Coastal erosion
California

1. Introduction
Coastal cliffs comprise a high proportion of the world's coasts (Emery and Kuhn, 1982), where almost one quarter of the global population resides (Small and Nicholls, 2003). Retreating coastal cliffs currently cause numerous problems for coastal populations and managers. Sea-level rise is expected to cause increased coastal cliff erosion rates for many areas (Sunamura, 1988; Bray and Hooke, 1997; Dickson et al., 2007; Nicholls et al., 2007; Trenhaile, 2010, 2014). Studies of coastal cliff erosion and retreat have increased in recent years (Naylor et al., 2010), highlighting a growing interest and need to study rock coasts. Yet our understanding of coastal cliff processes and behavior is complicated by the wide array of erosional processes that occur (Trenhaile, 1987; Sunamura, 1992; Rosser et al., 2007; Kennedy et al., 2011), variable temporal changes and processes (Cambers, 1976; Dornbusch et al., 2008; Lee, 2008), geomorphic feedbacks (Sunamura, 1976; Kline et al., 2014; Young, 2015), and highly variable geologic, oceanographic, and climatic settings.

Actively eroding coastal cliffs comprise the majority of the California coast (Fig. 1) and threaten development throughout the State, including highways, railways, wastewater, oil, natural gas and nuclear facilities, universities, military bases, and numerous state beaches and parks in addition to homes and businesses. Episodic cliff failures have caused human injury and several deaths in recent years (e.g. Perry, 2000; Gross and Davis, 2008; Evans, 2015). Seawalls and rock armoring are increasingly used to prevent erosion, but eroding coarse-grained coastal cliffs can be an important source of sediment to beaches (Young and Ashford, 2006; Brooks and Spencer, 2010; Young et al., 2010a; Mushkin et al., 2016), which are important cultural and economic resources that generate billions of dollars annually in California. These problems will worsen as sea levels and coastal populations continue to increase, and effectively managing California's changing coast will become increasingly challenging.

Coastal cliff erosion is broadly attributed to marine and subaerial (including subsurface) erosion mechanisms (Trenhaile, 1987; Sunamura, 1992). Subaerial mechanisms (e.g. groundwater processes, rilling, slope wash) act over the entire cliff face, and beneath the surface. Rainfall has been empirically linked to inland landsliding (Caine, 1980), where marine processes are not active, and serves as an indicator of subaerial forcing.

Young et al. (2009b) found a high correlation between the timing of rainfall and coastal cliff erosion in southern California. Brooks et al. (2012) discussed the importance of the sequence of rain events on sub-surface pore water pressures and cliff stability. Marine processes (e.g. wavedriven impact pressures and abrasion) act directly only at the cliff base, and only when tides and other water level fluctuations allow waves to reach the cliff (Sunamura, 1992; Rosser et al., 2013; Vann Jones et al., 2015; Young et al., 2016). While marine and subaerial processes drive cliff erosion, geologic conditions dictate cliff resistance and control the seacliff failure mode. The relative importance of marine and subaerial Geomorphology 300 (2018) 164–175
E-mail address: [email protected].
https://doi.org/10.1016/j.geomorph.2017.10.010
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June 6, 2022 Item 13
processes varies in space and time, and observations of cliff erosion and forcing (e.g. ocean waves and rain) are needed to establish these relationships. Brooks et al. (2012) established both marine and subaerial process thresholds associated with high magnitude cliff retreat events for soft cliffs on the Suffolk coast, U.K. and concluded the driving mechanisms vary through time.

Historical cliff retreat has been measured with historical maps and aerial photographs in a variety of locations worldwide, including Portugal (Marques, 2008), the United Kingdom (May and Heeps, 1985; Brooks and Spencer, 2010), Italy (Budetta et al., 2000), Australia (Bezore et al., 2016), Canada (Lantuit and Pollard, 2008), and India (Sajinkumar et al., 2017). LiDAR is increasingly used to measure more recent cliff retreat and erosion and has been applied in the United Kingdom (Adams and Chandler, 2002; Rosser et al., 2005; Earlie et al., 2015), Portugal (Nunes et al., 2011), the United States (e.g. Sallenger et al., 2002; Young and Ashford, 2006), Canada (Obu et al., 2016), Israel (Katz and Mushkin, 2013) and France (Letortu et al., 2015).

Other methods to measure cliff retreat and erosion include using fixed markers in the United Kingdom (Williams and Davies, 1987), field surveys in Australia (Gill, 1973), micro-erosion meters (MEM) in New Zealand (Stephenson and Kirk, 1996) and measuring shore platform widths in New Zealand (de Lange and Moon, 2005).

Coastal cliff retreat studies in California date back at least to 1932 (Vaughan, 1932). Since then, numerous studies of California cliff retreat have been conducted using a variety of measurement techniques ranging from dated inscriptions (Emery and Kuhn, 1980) to terrestrial LiDAR (Collins and Sitar, 2008). These studies are often site-specific or local in scale, but Griggs et al. (2005) and Dare (2005) provide statewide compilations of many of these studies, and U.S. Army Corps of Engineers (1971) provides a qualitative statewide erosion assessment. Hapke et al. (2009) conducted the most recent systematic study and mapped retreat along 350 km of California cliffs using T-sheets from the 1920s and 1930s and airborne LiDAR data collected in 1998 and 2002. Using shore-normal transects spaced 20 m alongshore, Hapke et al. (2009) calculated mean and maximum cliff top retreat rates of 0.3 m/yr and

3.1 m/yr, respectively, with estimated errors of 0.2 m/yr. The highest retreat rates were in central and northern California, associated with large slumps and deep-seated coastal landslide activity, often triggered by elevated rainfall and associated increased pore water pressures (Thomas and Loague, 2014; Young, 2015).

Advances in cliff mapping with airborne LiDAR surveys (Matsumoto et al., 2017) provide unprecedented detail of volumetric and cliff top change over large areas, but existing studies in California have limited spatial extent (i.e. Young et al., 2009a, 2010b, 2011). This study provides the first large-scale assessment of coastal cliff erosion and retreat in California using high-resolution airborne LiDAR data collected in 1998 and 2009–2010. Both cliff top retreat and the average retreat of over the cliff face are quantified and used to explore changes on different parts of the cliff profile. The results are compared with historical retreat rates, alongshore metrics of erosion forcing mechanisms, and rock strength. A cliff hazard metric described by Young et al. (2009a) is used to locate areas prone to future cliff top failures.

2. Study site

2.1. Geologic setting
The study site extends 1100 km from the Mexico/California border to Bodega Head, California (Fig. 1). The California coast is tectonically active and contains numerous fault zones, most notably the San Andreas Fault dividing the North American and Pacific plates. Past tectonic processes produced several coastal mountain ranges and a series of uplifted marine terraces along much of the coastline. The majority of coastal Fig. 1. a) Map of California's coastal cliffs/rocky shoreline and the LiDAR study area spanning 1100 km of shoreline. LiDAR data coverage was incomplete in some regions (boxes) resulting in 595 km of cliffed shoreline for analysis. Rain (circles) and tide (triangle) gauges used for this study were located alongshore in the study area. Example photos of representative California coastal cliff settings: b) low relief cliffs fronted by a beach in Goleta, c) high relief cliff at Torrey Pines, La Jolla and d) cliff top development, sea caves, and crenulated cliff line in Sunset Cliffs, San Diego. Photographs used with permission, ©2002–2017 Kenneth and Gabrielle Adelman, California Coastal Records Project www.Californiacoastline.org.

A.P. Young / Geomorphology 300 (2018) 164–175 165
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cliffs are low relief cliffs cut into the uplifted marine terraces while the rest are high relief cliffs and coastal mountains (Griggs et al., 2005).

Cliffs cut into the marine terraces are generally composite cliffs composed of two geologic units: a more resistant lithified Cenozoic mudstone, shale, sandstone and siltstone, and an upper unit of weakly lithified Quaternary terrace deposits (Griggs et al., 2005). Low-relief cliffs composed of alluvium or terrace deposits also exist where the lower unit is locally absent. The cliffs are generally 10–30 m in height, but exceed 100 m in some areas. Cliff heights remain generally constant as the cliff recedes because most cliff tops are relatively flat terrace features. The cliffs are typically fronted by a wave-cut platform usually covered by a veneer of beach sand and sometimes cobble. The beaches, which act as a buffer to direct wave-driven cliff erosion, are often narrow and occasionally stripped of sediment during large winter storms.

Cliff profiles differ alongshore and their geometries are related to the relative importance of marine and subaerial processes, cliff composition, and phases of cliff profile evolution (Emery and Kuhn, 1982).

2.2. Oceanography
The California coast is exposed to waves generated by local winds and distant storms in both hemispheres (Flick, 1994). During winter, swell from the North Pacific and Gulf of Alaska is most energetic, whereas swell from the South Pacific dominates in summer. Waves reaching the southern California coast undergo a complex transformation, and shadows of the Channel Islands create strong alongshore variations in wave height (Pawka, 1983). Annual nearshore wave energies are generally larger in central (defined here as Point Conception to Bodega Head) and northern California compared to southern California (south of Point Conception). The tide range reaches up to 2.6 m during spring tides, so large swells arriving during relatively low tide may not reach the cliffs, whereas moderate swell arriving during high tide can have significant wave-cliff impact duration (Young et al., 2016).

2.3. Climate
The climate is characterized by dry summers and occasionally wet winters, with most rainfall occurring from November to March.

Prolonged drought, very wet years, and multi-decadal scale precipitation cycles can cause high variation in annual rainfall (Michaelsen et al., 1987; Haston and Michaelsen, 1994). Annual coastal precipitation generally increases northward with mean annual precipitation ranging from 257 mm in San Diego to 1032 mm near Bodega Head (www.wrcc. dri.edu), but is locally higher along the Big Sur coast and lower in the San Francisco and Monterey areas. Strong El Niño events are usually associated with elevated winter precipitation, wave heights, and sea levels, causing increased coastal erosion, flooding and damage (Flick, 1998; Storlazzi and Griggs, 2000; Strolazzi et al., 2000; Barnard et al., 2017). Annual precipitation during the study was near average except during the winter of 2004–2005 when some regions received more than twice the annual mean precipitation.

3. Methods

3.1. LiDAR data
Airborne LiDAR datasets collected in 1998 and 2009–2010 (coast.noaa.gov/digitalcoast/; Table 1) provide regional coverage from the California-Mexico border to Bodega Head, with some gaps, notably along the Big Sur Coast (Fig. 1). A 2002 LiDAR dataset provides additional spatial coverage but was not used here because of low point density (probably from fewer aircraft flight passes) and data gaps. However, a cliff top line digitized by Hapke and Reid (2007) from the 2002 LiDAR was used in some localized areas. The overall coverage for this study includes 595 km of cliffs.

The LiDAR survey contractors estimated vertical root mean square error of the 1998 and 2009–2010 point data at 0.15 m, with horizontal accuracies of 0.5–0.80 m. LiDAR point data were processed into 1-m resolution digital elevation models using the last return (if multiple returns were available) and a natural neighbors technique. Typical point density of the 1998 and 2009–2010 datasets are 0.5 and 1.5 points/m2 ,
respectively.

3.2. Cliff erosion and cliff face retreat (1998 to 2009–2010) Digital change grids, estimated by differencing successive digital elevation models created using these LiDAR datasets, show both negative (erosion) and positive (accretion, talus deposits) changes. Sources of digital change grid error include the basic LiDAR observations, spatial interpolation, and vegetation. The vertical root mean square difference (RMSZ) between surveys was estimated at 0.36 m using 14 control areas spread throughout the study area. Control areas representative of coastal cliff topography consisted of inland hillsides and slopes assumed to experience no change during the study period. RMSZ was calculated for each control area using the digital change grid raster values.

Elevation changes can indicate landslide motion, land erosion, talus deposition, topographic beach changes, and anthropogenic changes.

The detected changes were programmatically filtered to remove noise and erroneous data. To do so, first all grid cells with a vertical change Table 1
2009–2010 lidar coverage and survey dates (Fugro, 2011).

South End North End Survey date Analysis time span (years, 1998 to 2009–2010)a Border La Jolla Shores November 2009 11.6
La Jolla Shores Dana Point Harbor October 2009 11.5
Dana Point Harbor Seal Beach October 2009 11.5
Seal Beach Point Dume October 2009 11.6
Point Dume Carpenteria November 2009 11.6
Carpenteria El Capitan November 2009 11.6
El Capitan Point Conception November 2009 11.6
Point Conception Oceano November 2009 11.6
Oceano Harmony November 2009, May 2010 11.6
Harmony Ragged Point November 2009 11.6
Ragged Point Point Sur November 2009, May 2010 11.7
Point Sur Moss Landing May 2010, June 2010, October 2010 12.1 Moss Landing Ano Neuevo June 2010, September 2010, October 2010 12.2 Ano Neuevo Pacfica June 2010, September 2010, November 2010 12.2 Pacifica Golden Gate June 2010, October 2010, November 2010 12.2 Golden Gate Tomales Bay September 2010, November 2010 12.4 Tomales Bay Sea Ranch September 2010, November 2010 12.4 a Longest date range.
166 A.P. Young / Geomorphology 300 (2018) 164–175
June 6, 2022 Item 13
of b1 m (about 3 ∗ RMSZ) were omitted. Next, a minimum topographic footprint was imposed, requiring N10 connected cells of positive or negative change. Finally, the filtered digital change data were checked visually and edited manually. Changes related to beaches, dunes, construction, and those areas inland of the coastal road were identified using aerial photographs and digital elevation model hillshades, and removed.

Changes were separated into negative (i.e. cliff erosion) and positive (i.e. talus deposits) volumetric changes and then evaluated in 5 m wide (in the alongshore direction) compartments. Dividing the volumetric compartment changes by the cliff height and compartment width (5 m) yielded bulk negative and positive cliff face changes, equivalent to average cliff retreat/advance over the cliff face (Fig. 2). Cliff/coastal slope heights were obtained from the digital elevation model.

The calculated volume changes under-estimate the actual changes because only relatively large volume and large footprint slides are detected. Thus, smaller topographic changes (such as a smaller individual rockfalls or localized surficial erosion) were not detected with the present methods. In a few locations such as Palos Verdes and Big Sur, the LiDAR swath did not fully cover the landward extent of coastal change, also causing an under-estimation of coastal change volumes.

3.3. Cliff top retreat (1998/2002 to 2009–2010).

Cliff top changes were measured using an existing 1998 (or 2002 in some locations) cliff top edge line from Hapke and Reid (2007) and a 2009–2010 cliff top edge line digitized manually for this study. The cliff top edge location was defined as the slope break between the cliff face and the cliff top. Areas were excluded where a definitive edge could not be identified. Cliff top retreat was measured at 5 m intervals alongshore using shore-normal transects. Negative cliff top retreat indicates landward cliff top movement (erosion). Measurements indicating seaward cliff top movement were assumed to result from data processing artifacts, and set to ‘no change’. In some localized areas, cliff top retreat measurements were removed because of variation in the identified cliff top edge feature between this study and Hapke and Reid (2007). Cliff edge uncertainties of 1.3 and 1.1 m for the 1998 and 2009–2010 datasets, respectively, were estimated as the sum in quadrature of the horizontal LiDAR accuracy (0.5 and 0.8 m) and digitizing error estimated at 1 m. The annualized error for cliff top retreat rates was estimated as the sum in quadrature of the two cliff edge uncertainties divided by the time span (11.6–12.4 years) at 0.14–0.15 cm/yr.

3.4. Historical cliff top retreat (1929–1934 to 1998/2002) Historical cliff edge lines from 1929 to 1934 and 1998/2002 (previously analyzed by Hapke and Reid, 2007) were reanalyzed at 5 m alongshore resolution for spatial consistency with the present analysis.

Measurements indicating seaward cliff top movement were set to ‘no change’. The error associated with these cliff retreat rates is estimated at 0.20 m/yr (Hapke and Reid, 2007).

3.5. Waves and total water level
Hourly tide levels were obtained from the La Jolla, Los Angeles, Santa Monica, Santa Barbara, Port San Luis, Monterey, and Point Reyes tide gauges (tidesandcurrents.noaa.gov). A wave buoy network (CDIP, cdip.ucsd.edu) was used to estimate hourly wave conditions at 8707 virtual buoys located in 10 m water depth spaced at 100 m intervals alongshore. The effects of complex bathymetry, and of varying beach orientation and wave exposure, were simulated with a spectral refraction wave model initialized with offshore buoy data (O'Reilly and Guza, 1991, 1998). The model has been used throughout California and validated extensively (O'Reilly et al., 2016). Time periods without data at all virtual buoys were removed, resulting in 46,258 h between November 2003 and November 2009 for wave data analysis.

The total water level is the sum of tides and the vertical height of wave run-up (Shih et al., 1994; Kirk et al., 2000; Ruggiero et al., 2001).

Time series of hourly total water level at the cliff base provide basic estimates of wave impact duration and a proxy for marine forcing. The vertical height of wave run-up (R2%) was approximated as the level exceeded by 2% of wave uprushes (Stockdon et al., 2006), using the formula:

R2% ¼ 0:043 HðÞ oLo 0:5
where the deep water wave height (Ho) used in the run-up equation was calculated by backing out nearshore wave height to deep water by reverse shoaling using linear wave theory, while the deep water wavelength (Lo) was calculated using the linear dispersion relationship (Dean and Dalrymple, 1991). Hourly total water level at each cliff location was interpolated with R2% and tide gauge data and used to calculate wave-cliff impact metrics, defined as the number of hours total water levels exceeded 2.5 and 3 m in elevation (NAVD88). 10 m
1m
1m 5m
10 m3
Top =
Face (-) =
Face (+) =
Face (Net) =
Volume (-) =
Volume (+) =
Volume (Net) =

0.0 -0.2

0.0 -0.2
-2.0

0.0 -2.0

0.0 -0.2

0.0 -0.2
-2.0

0.0 -2.0
-1.0
-0.2

0.0 -0.2
-2.0

0.0 -2.0
-1.0
-0.2
+0.2

0.0 -2.0
+2.0

0.0 0.0
-0.2
+0.2

0.0 -2.0
+2.0

0.0 Cliff Change Measurements
a bcde
Erosion
Talus Deposit
10 m3
10 m3
10 m3
10m3
10 m3
10 m3
Cliff Retreat (m)
Cliff Erosion (m /m) 3
a b c d e
Fig. 2. Interpretations of idealized cliff changes using the different retreat and erosion estimates.

A.P. Young / Geomorphology 300 (2018) 164–175 167
June 6, 2022 Item 13

3.6. Coastal armoring and setting
Coastal armoring present in 2010 was mapped by updating and amending a 2004 database of coastal armoring (Dare, 2005) using 2010 oblique coastal photographs (California Coastal Records Project).

The general coastal setting (rocky coast, sandy beach, cliff fronted by beach, etc.) was categorized and mapped alongshore using maps from Griggs et al. (2005) and 2010 oblique photographs (California Coastal Records Project). An accurate time series of beach width could not be established for the study area because of limited data availability and variable survey dates (Table 1) combined with large seasonal beach fluctuations, sometimes N50 m (Doria, 2016).

3.7. Rock strength
Nine hundred and thirty three in situ cliff rock strength measurements were made with Proceq Schmidt Hammers Type L and N at the cliff base using the ASTM method (ASTM, 2013). The ASTM method calculates the rebound value as the mean of 10 readings with outliers removed. Type L and N hammers were compared using 20 in situ measurements on a variety of rock types and combined with measurements from Kennedy and Dickson (2006) for calibration. Type L and N measurements were highly correlated (r2 = 0.98), and Type N hammer measurements were converted to Type L for consistency. Schmidt hammer measurements were typically spaced 50–100 m alongshore in the sections evaluated. For each cliff compartment rebound measurements located within 100 m were used to evaluate rock rebound statistics including the minimum, maximum, mean, and non-zero mean.

Similar rock rebound metrics were also evaluated using rebound measurements within 500 and 1000 m of each cliff compartment. Site access logistics limited most rock strength measurements to cliffs fronted by beaches.

3.8. Precipitation
Total precipitation during the study period was estimated by interpolating daily precipitation records from 18 coastal sites distributed over the study area to each 5 m alongshore compartment (Fig. 1; www.wrcc.dri.edu/).
f) California
Coastline
San
Diego
Los Angeles
Monterey
Point Conception
San
Francisco
Bay/Harbor
Beaches
Cliff
Armoring
a) Coastal
Setting
0 200
400
600
800
1000
Alongshore Location (km)
0 200 400
b) Cliff / Slope
Elevation
(m)
0 5000 10
c) Total
Water
Level
Index
(Hours)
5 10
d) Study
Period
Rainfall
(m)
0 50
e) Rock
Hammer
Rebound
0 0.1

0.2 0.3

0.4 0.5

0.6 0.7

0.8 0.9
1 3
MinMaxMean (non-zero)
0 Fig. 3. Alongshore comparison of (a) coastal setting and classification, (b) cliff or coastal slope height, (c) total water level index (hours above 2.5 m NAVD88), (d) interpolated study period total precipitation, (e) Schmidt hammer rebound metrics (within 1 km of compartment location) and (f) coastline reference map with hashes at 200 km intervals. Lower rebound metrics correspond to weaker rocks.
168 A.P. Young / Geomorphology 300 (2018) 164–175
June 6, 2022 Item 13

3.9. Cliff top hazard index
Over long periods, cliff face and cliff top retreat measurements will converge. However over shorter time periods, these measures can differ substantially and provide information on geomorphic change and cliff stability. Cliff top retreat reduces the overall cliff slope, while cliff base and cliff face erosion (not concentrated at the cliff top) cause slope steepening, thus reducing overall cliff stability. Young et al. (2009a) suggested the difference between cliff top and cliff face erosion could be used as a cliff top retreat hazard index. For example, as the cliff face retreat exceeds cliff top retreat, the cliff becomes more unstable, and vice versa. A cliff top hazard index, defined here as the recent cliff top retreat rate (positive values set to zero) minus the recent cliff face net retreat, increases with overall cliff steepening. Positive hazard values indicate the cliff face retreat rates exceed the cliff top retreat rates, suggesting a higher potential for future cliff top failure.

4. Results

4.1. Coastal setting
Seventy percent of the studied shoreline contains coastal cliffs, with 57% fronted by beaches (Fig. 3a, Table 2). Beaches without cliffs occupy 27% of the shoreline, with the remaining 3% of the coastline consisting of harbors and waterways. Total water level index metrics were consistently higher north of Point Conception (Fig. 3c). Eighteen percent of alongshore compartments contained some level of coastal armoring (Fig. 3a). Armoring is more prevalent in southern California probably because of higher density coastal populations and development, despite lower nearshore wave energies. Rock rebound values were relatively low in the San Diego area (Table 2), but generally varied widely in the sampled areas (Fig. 3e).

4.2. Cliff changes
Recent (1998 to 2009–2010) cliff changes N10 m3 were detected in 45% of the 5 m alongshore compartments (267 of 595 km; Table 3, Fig. 4d). Recent net volumetric cliff change rates ranged from −527 (erosion) to 128 (accretion) m3
/m/yr with a mean of −1.78 m3/m/yr
(Table 3). Recent net cliff face retreat ranged from −3.8 (landward) to

0.67 (seaward) m/yr with a mean of −0.042 m/yr (Table 3, Fig. 4c).

Recent cliff top retreat rates ranged from −4.2 to 0.0 m/yr, with a mean of −0.12 m/yr (Table 3, Fig. 4b) for the 236 km evaluated. In comparison, historical (1929–1934 to 1998/2002) cliff top retreat rates ranged from −3.1 to 0.0 m/yr, with a mean of −0.25 m/yr (Table 3, Fig. 4a) for the 283 km evaluated. Across the 169 km of cliffs where both historical and recent cliff top rates exist, the mean historical and recent cliff top retreat rates were −0.22 and −0.12 m/yr, respectively.

Numerous cliff erosion and retreat hot spots were detected throughout the study area (Fig. 5). Many of the erosion hot spots were related to deep-seated and/or complex coastal landslides such as in Daly City, Table 2
Coastal setting, cliff change, and cliff top hazard statistics by county.

County Length
in study
area
(km)
Classification (%) Mean
wave
impact
indexa
Mean
rock
rebound
valuea
Mean
recent
cliff top
retreat
(m/yr)
Mean
recent
cliff face
retreat
(m/yr)
Length of
cliff top
evaluated
(km)
Length of
cliff face
evaluated
(km)
Cliff top hazard index
Armored Beach Cliff &
beach
Cliff/Rocky Bay/Harbor Mean Mean
of positive
values
Percent
positive
values
(%)
Sonoma 7 2 42 25 26 7 2538 NaN −0.32 −0.01 1 6 −0.31 0.005 10 Marin 111 3 21 42 33 3 2872 28 −0.21 −0.07 21 75 −0.06 0.11 54 San Francisco 19 23 26 23 23 28 2375 32 −1.08 −0.16 0 9 −0.82 0.12 11 San Mateo 82 10 13 52 32 3 3951 27 −0.16 −0.09 23 74 −0.05 0.09 34 Santa Cruz 62 24 18 49 33 0 1854 34 −0.09 −0.04 21 57 −0.05 0.04 28 Monterey 167 4 20 13 66 1 2547 NaN −0.13 −0.01 15 63 −0.17 0.04 23 San Luis Obispo 140 8 24 21 53 1 1963 NaN −0.04 −0.04 24 41 0.01 0.05 62 Santa Barbara 176 12 22 70 8 0 1317 37 −0.11 −0.05 66 102 −0.05 0.06 42 Ventura 67 55 52 31 15 2 399 NaN NaN 0.00 0 13 NaN NaN NaN Los Angeles 117 27 21 51 13 14 325 38 −0.09 −0.02 18 59 −0.07 0.02 22 Orange 67 42 54 35 8 4 380 37 −0.09 −0.01 6 22 −0.07 0.01 25 San Diego 120 31 40 45 12 3 558 16 −0.14 −0.02 40 74 −0.12 0.03 15 All 1133 18 27 40 30 3 1683 18 −0.12 −0.04 236 595 −0.07 0.05 33 a Compartment means for wave and rock metrics shown in Fig. 2.

Table 3
Summary of cliff change statistics.

Maximum erosion or
landward movement
Maximum accretion or
seaward movement
Mean Standard deviation Percentage of nonzero
compartment observations (%)
Cliff volume change rate (m3
/m/yr)
1998 to 2009–2010
Negative (erosion) −527 0 −1.95 9.66 44
Positive (accretion) 0 136 0.17 2.27 4
Net −527 128 −1.78 9.56 45
Cliff face retreat rate (m/yr)
1998 to 2009–2010
Negative (erosion) −40 −0.045 0.141 44
Positive (accretion) 0 1.12 0.0023 0.028 4
Net −3.8 0.67 −0.042 0.14 45
Cliff top retreat rate (m/yr)
1998/2002 to 2009–2010
Negative (landward) −4.2 0 −0.12 0.27 55
Cliff top retreat rate (m/yr)
1929–1934 to1998/2002
Negative (landward) −3.1 0 −0.25 0.28 99
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Portuguese Bend, and San Onofre, consistent with previous studies (Hapke et al., 2009; Young et al., 2009b; Young, 2015).

4.3. Cliff top hazard index
The cliff top hazard index ranged from −3.7 to 1.7 (Fig. 4e) with a mean of −0.07, indicating more areas experienced cliff flattening as opposed to cliff steepening. However, 33% of compartments with both cliff top retreat and cliff face retreat observations had a positive hazard index. Locations with large cliff top hazard values (N1) include San Onofre State Beach, Big Sur, Martin's Beach, Daly City, and near Double Point in Point Reyes National Seashore. San Luis Obispo County had the highest overall mean hazard index but the mean index of cliff steeping locations (positive hazard values) was relatively low (Table 2). Marin, San Francisco, and San Mateo Counties, all in the northern part of the study area, had the highest mean index of cliff steepening locations. Marin, San Luis Obispo, and Santa Barbara Counties had the highest percentages (42–62%) of cliff steepening locations (Table 2).

Additional future surveys are needed to test the applicability of this experimental hazard index.

5. Discussion

5.1. Influence of coastal setting
Correlations between total water level metrics and recent cliff changes were not significant at spatial scales between 5 m–0.5 km (averaging alongshore), but became statistically significant (p b 0.01) at 0.5 km scale, and increased to a maximum of ~0.15 (r2 ) at 15 km
scales. At larger scales, the correlations became unstable with high r2 fluctuations. Although not available for this study, incorporating time series data of beach widths and elevations to assess wave-cliff impacts may improve correlations between marine forcing and cliff retreat.

Neither precipitation nor rock rebound metrics were well correlated with cliff retreat at any spatial scales. This could be because of the relatively low sampling resolution for rainfall and rock strength compared with cliff changes, or that other local parameters such as sea spray, e) California
Coastline
San
Diego
Los Angeles
Monterey
Point Conception
San
Francisco
1 2,3
5 6
7 4
-4-20
a) Cliff Top
Retreat
1929-1934 to
1998/2002
0 200
400
600
800
1000
-4-20
b) Cliff Top
Retreat
1998/2002 to
2009-2010
-4-20
c) Net Cliff
Face Retreat
1998 to
2009-2010
-2000
d) Net Cliff
Volume Change
1998 to
2009-2010
m3/m/yr
-2 0 2
e) Cliff Top
Hazard Index
Alongshore Location (km)
4 1
5 2,3
5 6 6
8 7
8 1
-527
Fig. 4. Alongshore comparison of (a) historical cliff top retreat (b) recent cliff top retreat (c) recent net cliff face retreat, (d) recent volumetric cliff change, (e) cliff top hazard index, and (f) coastline reference map with hashes at 200 km intervals. Positive cliff top hazard index numbers indicate higher hazard and slope steepening. Numbers show cliff retreat hot spots and high cliff top hazard locations at (1) San Onofre State Beach, (2) Portuguese Bend, (3) Palos Verdes, (4) Big Sur, (5) Martins Beach, (6) Daly City, (7) Double Point, and (8) Point Reyes. The net cliff volume change (d) at about km 1000 extends beyond the plot (dashed line) to −527 m3 /m/yr.
170 A.P. Young / Geomorphology 300 (2018) 164–175
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wind, and beach elevations are influencing cliff retreat. For example, rainfall runoff directed onto specific cliff areas can create erosion hot spots unrelated to cliff hardness or regional rainfall quantities. Additionally, the decadal time span averages out high magnitude rain and wave events causing the cliff erosion. The processes driving cliff erosion vary in space and time, and alongshore differences in cliff stage profile development and the stochastic nature of cliff failures probably also limited cliff erosion correlations. As identified in previous work (e.g. Young et al., 2009b; Young, 2015), rainfall may be better correlated with cliff erosion when compared in time series rather than the spatial comparison used here because time series analysis of a particular cliff section reduces cliff setting variables (such as geologic conditions) that are difficult to quantify.

Mean cliff face and cliff top retreat rates in central California were 86% and 30% larger, respectively, compared to southern California.

Similarly, mean metrics of wave-impact and precipitation were also higher in central California, suggesting possible relationships at these regional scales; however additional data are needed to test this relationship statistically.

On average, unarmored cliffs retreated (−0.054 m/yr cliff face retreat) about 3 times more than armored cliffs (−0.019 m/yr, Fig. 6a). Cliffs fronted by beaches retreated 49% more (−0.061 m/yr cliff face retreat) than those without beaches (−0.041 m/yr, Fig. 6a).

This observation is counter-intuitive because beaches protect cliffs from wave erosion (Jones and Williams, 1991; Lee, 2008), but is consistent with previous studies (Robinson, 1977). This observation suggests beaches in the study area tend to form at locations with relatively weak cliffs and where sufficient sand supply exists. It also highlights the possible role of beach sediment as an abrasive that may accelerate cliff retreat (Sunamura, 1982, 1992; Kline et al., 2014). Additional rock Fig. 5. Examples of significant coastal cliff changes at (a) Point Reyes National Seashore, (b) Martin's Beach, (c) Daly City and Pacifica, (d) Portuguese Bend, and (e) Palos Verdes. Inland lines in panels c and d show LiDAR analysis boundary, indicating possible additional cliff changes occurring further inland. See Fig. 4 for mapped locations.

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strength sampling at sites without beaches, and an evaluation of the beach protective capacity may help test this hypothesis. It is unknown if this relationship will hold over longer time periods, however it is consistent with long-term modeling (Limber et al., 2014; Limber and Murray, 2014) suggesting beaches accumulate in embayments composed of weak rock. This finding is also consistent with wave refraction around headlands that generate gradients in alongshore sediment flux and sediment deposition in embayments (May and Tanner, 1973; Komar, 1985; Carter et al., 1990; Trenhaile, 2016).

Taller cliffs experienced more overall erosion (Fig. 6c), but cliff face retreat rates were generally uninfluenced by cliff height except for low height cliffs (0–10 m) that retreated slower than all other cliffs (Fig. 6b). The reason for the small retreat rates of low cliffs is unknown, but could be from erosion-resistant low cliffs that sometimes lack the weaker upper Quaternary layer (for example in the Monterey area).

At 5 m compartment scale, cliff height was not correlated with recent cliff retreat or erosion. However when retreat rates from unarmored cliffs were binned by height (10 m bins), the mean cliff height for each bin was significantly correlated with mean erosion rate when bins with fewer than 1000 observations were excluded (r2 = 0.71, Fig. 6c). This correlation between mean binned cliff retreat rates and unarmored cliff height decreased when bins with fewer observations were considered.

5.2. Comparison to historical retreat rates
Distributions of historical and recent retreat rates were all skewed towards smaller magnitude events, but historical retreat rates were more evenly distributed and included higher percentages of large magnitude retreat rates (Fig. 7). The more evenly distributed historical cliff retreat could be because longer time periods average out the stochastic nature of cliff retreat, and suggests the system moves towards more spatially uniform retreat rates with time. 12.6, 4.7, and 1.3% of historical cliff top, recent cliff top, and recent cliff face retreat rates, respectively, exceeded −0.5 m/yr. Mean recent cliff top and cliff face retreat rates were lower than mean historical cliff top retreat rates by 52% and 83%, respectively (mean rates include zero change locations). The reason for the substantially lower rates is unknown but could be related to extensive anthropogenic alterations to the coastal system, different overall time scales (~70 vs. ~10 years), the episodic nature of cliff retreat, changes in ocean or subaerial forcing between these time periods, and/or variable quality of data sources. Additional retreat measurements over a wider variety of timescales are needed to test for timescale-dependence of erosion rates observed in other natural systems with intermittent erosion events (e.g. Finnegan et al., 2014; Ganti et al., 2016). However, in these other systems erosion rates are higher over shorter time intervals, opposite to the smaller decadal scale rates observed here. This opposition could be from the large spatial area evaluated here that can reduce the timescale-dependence of erosion rates (Sadler and Jerolmack, 2015; Ganti et al., 2016). Historical and recent maximum retreat rates were of similar magnitude.

Overall comparison of historical and recent individual compartment retreat rates (Fig. 8a, b) suggests they are not well correlated. However, historical and recent retreat rates are significantly (p b 0.01) inversely correlated for areas that experienced relatively large historical or recent cliff retreat, such that recent retreat rate decreases with elevated historical retreat. The strength of the inverse correlation increases with cliff change magnitudes up to r2 = 0.91 (Fig. 8d, e). This result suggests that using site-specific historical retreat rates to predict or project future decadal scale cliff retreat (and possibly longer time scales) using historical data could be problematic because of the varying timescales, forcing mechanisms, and system feedbacks. The stochastic nature of cliff retreat also complicates predictions when time scales vary and the time elapsed since previous failures is not considered. The inverse correlation is probably driven by geomorphic feedbacks, such that after a large cliff top failure, the cliff becomes relatively inactive from (1) a decrease in cliff slope and (2) increased wave protection from talus (and resulting beaches, when the cliffs contain sufficient beach-size sediment). These findings are consistent with Lee (2008) who found that extrapolating historical retreat is problematic without incorporating cliff-beach dynamics and forcing mechanisms over the observation period. -10 -4 -10 -2 -10 0
Net Cliff Face Retreat Rate (m/yr)
40 60
80 100
Cumulative Percentage (%)
-10 -4 -10 -2 -10 0
Unamored Net Cliff Face Retreat Rate (m/yr)
20 40
60 80
100
Cumulative Percentage (%)
-10 -2 -10 0 -10 2
Unarmored Net Cliff Face Erosion Rate (m3/m/yr)
20 40
60 80
100
Cumulative Percentage (%)
0 - 10
10 - 20
20 - 30
30 - 40
40 - 50
50 - 60
60 - 70
70 - 80
80 - 90
90 -100
100 -110
140 -150
Cliff Height (m)
Armored
Unarmored
Unarmored With Beach
Unarmored No Beach
All Cliffs
Cliff Category
a)
b)
c)
Fig. 6. Cumulative distributions of recent 1998 to 2009–2010 (a) cliff face retreat rate for armored, all unarmored, unarmored with/out beaches, and all cliffs, (b) cliff face retreat rate (erosion normalized by cliff height) for cliffs separated by cliff height (colors), and (c) cliff face erosion rate for cliffs separated by cliff height (colors). For panels b & c, only binned height ranges with at least 1000 observations are shown. 172 A.P. Young / Geomorphology 300 (2018) 164–175
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6. Summary
LiDAR data collected in 1998 and 2009–2010 were used to measure decadal scale coastal cliff erosion and cliff top retreat from the Mexico/ California border to Bodega Head, California. Cliff face erosion was detected along 44% of the 595 km of cliffs evaluated. Mean cliff face and cliff top retreat rates were −0.04 and −0.12 m/yr, respectively, notably lower than historical (1929–1934 to 1998/2002) retreat rates of −0.25 m/yr. The lower recent rates could be from anthropogenic changes, varying time periods and forcing mechanisms, the stochastic nature of cliff retreat, and variable quality data sources. Distributions of historical retreat rates were spread more evenly and included higher percentages of large magnitude retreat rates, probably because the longer time span captured more locations that experienced episodic large cliff retreat events, thus spatially averaging out retreat rates. Large magnitude historical cliff retreat rates were inversely correlated with recent cliff retreat rates, suggesting possible problems with using historical retreat rates to project future cliff positions. The inverse correlation is probably driven by the episodic nature of large cliff retreat events, geomorphic feedbacks, and the cliff retreat cycle.

Maximum landward cliff top and cliff face retreat rates were about 4 m/yr, similar to maximum historical retreat rates. Localized high rates of coastal cliff change were found in Palos Verdes, Daly City, San Onofre State Beach, Point Reyes National Seashore, and Martin's Beach and were often related to deep-seated and/or complex coastal landslides. Alongshore metrics of wave-cliff impact, precipitation, and cliff hardness generally did not correlate well with recent cliff retreat rates.

On average, unarmored cliff faces retreated about three times further than armored cliffs. Although beaches can prevent wave-driven erosion, cliffs fronted by beaches retreated faster than those without beaches.

However, the influence of beach width was not considered here, and narrow beaches that provide little erosion protection might have influenced this outcome. These findings highlight the need to monitor beach and cliff changes concurrently and examine the protective role of beaches in cliff processes.

The difference between cliff face change and cliff top retreat were used to quantify cliff steeping and establish a cliff top hazard index.

Locations with relatively large cliff steeping and cliff top hazard values include San Onofre State Beach, Big Sur, Martin's Beach, Daly City, and near Double Point. Additional surveys are needed to test the hazard index and identify hazard thresholds and probable timing of future failures.

Acknowledgments
APY was funded by the California SeaGrant (NA14OAR4170075) and California Department of Parks and Recreation, Division of Boating and Waterways (DPR-DBW) with the University of California. Wave data was sponsored by the California DPR-DBW with the University of California and USACE, as part of the Coastal Data Information Program (CDIP). Patrick Limber at USGS graciously provided about 200 Schmidt Hammer rebound observations north of Point Conception. Lucian Parry conducted parts of the GIS analysis. Jessica Carilli provided thoughtful editing and assisted with Schmidt Hammer field measurements. Bob Guza and Ron Flick provided important support for this research. -3 -2.5 -2 -1.5 -1 -0.5 0 0.5
Cliff Retreat Rate (m/yr)
0 10
20 30
40 50
60 70
80 90
Percentage Density (%)
Cliff Top Historical
Cliff Top Recent
Net Cliff Face Recent
Fig. 7. Binned (0.1 m) distribution of historical and recent cliff retreat rates. Negative values indicate landward retreat.

Fig. 8. Comparison of (a) historical (1929–1934 to 1998/2002) cliff top and recent (1998/2002 to 2009–2010) cliff top retreat, (b) historical cliff top and recent cliff face retreat, and (c) recent cliff top and recent cliff face retreat. Color bars represent grid point density. (d–f) Correlations of retreat rates of corresponding top panels (a–c) for alongshore compartments with minimum historical or recent retreat rate magnitudes.

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Thomas, M.A., Loague, K., 2014. Devil's slide: an evolving feature of California's coastal landscape. Environ. Eng. Geosci. 20 (1), 45–65.

Trenhaile, A.S., 1987. The Geomorphology of Rock Coasts. Oxford University Press, New York, p. 384.

Trenhaile, A.S., 2010. Modeling cohesive clay coast evolution and response to climate change. Mar. Geol. 277 (1), 11–20.

Trenhaile, A.S., 2014. Climate change and the impact on rocky coasts. In: Kennedy, D.A., Stephenson, W.J., Naylor, L.A. (Eds.), Rock Coast Geomorphology: A Global Synthesis.

Geol. Geological Society of London Memoirs 40, pp. 7–17.

Trenhaile, A.S., 2016. Rocky coasts―their role as depositional environments. Earth Sci.

Rev. 159, 1–13.

U.S. Army Corps of Engineers, 1971. National Shoreline Study California Regional Inventory.

USACE South Pacific Division, San Francisco (106p).

Vann Jones, E., Rosser, N.J., Brain, M.J., Petley, D.N., 2015. Quantifying the environmental controls on erosion of a hard rock cliff. Mar. Geol. 363, 230–242.

Vaughan, T.W., 1932. Rate of sea cliff recession on the property of the Scripps Institution of Oceanography at La Jolla, California. Science 75, 250.

Williams, A.T., Davies, P., 1987. Rates and mechanisms of coastal cliff erosion in Lower Lias rocks. In Coastal Sediments (1855–1870). ASCE.

Young, A.P., 2015. Recent deep-seated coastal landsliding at San Onofre State Beach, California. Geomorphology 228, 200–212.

Young, A.P., Ashford, S.A., 2006. Application of airborne LIDAR for seacliff volumetric change and beach-sediment budget contributions. J. Coast. Res. 22, 307–318.

Young, A.P., Flick, R.E., Gutierrez, R., Guza, R.T., 2009a. Comparison of short-term seacliff retreat measurement methods in Del Mar, CA. Geomorphology 112, 318–323.

Young, A.P., Guza, R.T., Flick, R.E., O'Reilly, W.C., Gutierrez, R., 2009b. Rain, waves, and short-term seacliff evolution. Mar. Geol. 267, 1–7.

Young, A.P., Olsen, M.J., Driscoll, N., Flick, R.E., Gutierrez, R., Guza, R.T., Johnstone, E., Kuester, F., 2010a. Comparison of airborne and terrestrial LIDAR estimates of seacliff erosion in southern California. Photogramm. Eng. Remote. Sens. 76, 421–427.

Young, A.P., Raymond, J.H., Sorenson, J., Johnstone, E.A., Driscoll, N.W., Flick, R.E., Guza, R.T., 2010b. Coarse sediment yields from Seacliff erosion in the oceanside littoral cell. J. Coast. Res. 26, 580–585.

Young, A.P., Guza, R.T., O'Reilly, W.C., Flick, R.E., Gutierrez, R., 2011. Short-term retreat statistics of a slowly eroding coastal cliff. Nat. Hazards Earth Syst. Sci. 11, 205–217.

Young, A.P., Guza, R.T., O'reilly, W.C., Burvingt, O., Flick, R.E., 2016. Observations of coastal cliff base waves, sand levels, and cliff top shaking. Earth Surf. Process. Landf. 41 (11), 1564–1573.

A.P. Young / Geomorphology 300 (2018) 164–175 175
June 6, 2022 Item 13
As California Cliffs Erode, UC San Diego Team Works to Track and Understand these Changes 6/3/22, 10:42 AM https://ucsdnews.ucsd.edu/feature/as-california-cliffs-erode-uc-san-diego-team-works-to-track-and-understand-these-changes Page 1 of 7 UC San Diego
UC San Diego News Center
By Lauren Fimbres Wood May 26, 2022
Advanced imaging and geotechnical technology are powering understanding of our coastline and its hazards
As California Cliffs Erode, UC San Diego Team
Works to Track and Understand these Changes
The Coastal Process Group at Scripps Instiution of Oceanography deploys a drone to conduct a LiDAR survey. Photo by Erik Jepsen/University Communications.

PTOFHILO
June 6, 2022 Item 13
As California Cliffs Erode, UC San Diego Team Works to Track and Understand these Changes 6/3/22, 10:42 AM https://ucsdnews.ucsd.edu/feature/as-california-cliffs-erode-uc-san-diego-team-works-to-track-and-understand-these-changes Page 2 of 7 T
The Beacons Beach switchback trail suffered damage in a landslide on May 2, 2022. Photo credit: Lauren Fimbres Wood. he cliff-top parking lot was fenced off and the trail marked “Unstable Cliffs - Active Landslide Area - Stay Back,” but that didn’t stop Adam Young and City of Encinitas officials from carefully traversing the uneven landscape at the Beacon’s Beach switchback trail to get a closer look. “There are definitely new cracks here,” said Young, a coastal geomorphologist and researcher at UC San Diego’s Scripps Institution of Oceanography.

Young studies coastal erosion, overseeing coastline surveys throughout the state of California that use advanced laser imaging technology—called LiDAR, which stands for Light Detection and Ranging—to create high-resolution maps of cliffs to measure how they are eroding and changing over time.

On May 2, 2022, a landslide at the Leucadia, California beach damaged part of the trail, closing the popular access point. Young and a team of fellow scientists from Scripps Oceanography went into rapid response mode, working
with city officials to conduct a LiDAR survey of the landslide and install advanced geophysical instruments to determine if the landslide was still moving.

At the site, a seismometer now monitors any shaking in the cliff face, a GPS monument allows for measuring ongoing changes in position of the cliff top, and wave pressure sensors measure wave impacts hitting the base of the cliff.

These pressure sensors allow scientists to measure how often the waves reach the base of the cliff and potentially contribute to the movement of the slide. “Right now the beach is pretty eroded, and you can see
the high tide water line is all the way up to the base of the cliff,” said Young on May 17, when he was back for
the installation and monitoring of equipment.

Tiltmeters, which Scripps geophysical engineer Frank
Wyatt typically uses to measure movement of the San
Andreas Fault, are instruments that can monitor slope
stability, measuring to an accuracy of 10 micrometers if the ground is continuing to move. Tiltmeters have also
been widely used across the U.S. and Europe to monitor
June 6, 2022 Item 13
As California Cliffs Erode, UC San Diego Team Works to Track and Understand these Changes 6/3/22, 10:42 AM https://ucsdnews.ucsd.edu/feature/as-california-cliffs-erode-uc-san-diego-team-works-to-track-and-understand-these-changes Page 3 of 7 Scripps researcher Adam Young points to an area north of the beach trail showing new cracks, indicating the area was still in an active landslide on May 17, 2022. Photo credit: Lauren Fimbres Wood. railroad tracks. They get adhered to railroad ties to
determine if a track has gone askew, and provide realtime monitoring to officials.

Most of the data is disseminated from the instruments using cellular signals to “the cloud.” Results of the data collected will be shared with city geotechnical experts to help determine when the landslide is done moving, and when the trail can reopen.

And while the team went into rapid response following the landslide, Beacon’s Beach is an area where Young and Scripps geophysicist Mark Zumberge are already conducting ongoing enhanced coastal monitoring. This research is funded as part of Assembly Bill 66, which was introduced by Assemblymember Tasha Boerner Horvath, whose district includes San Diego’s coastal North County.

The legislation was spurred in part by a fatal accident in which a 30-by-25-foot sandstone chunk broke loose and fell onto three women at Grandview Beach in Encinitas in August 2019.

The bill has allowed for an expansion of coastal LiDAR
surveys from Black’s Beach to Carlsbad. The surveys are now being conducted weekly. The LiDAR system, which
can be operated by a truck-mounted system or drone
depending on the width of the beach and other factors,
sends hundreds of thousands of laser pulses per second.

When the laser pulse hits an object, the laser signal
bounces back to the LiDAR instrument, yielding a detailed measurement of the time it takes the laser to return to the Warning Signs of Potential Cliff Failure
“It’s very important to keep your distance from cliffs,” said Young. “Elevated rainfall and groundwater can trigger failures in our area, but cliff failures can happen any time.” Young outlines some warning signs to look out for.

Warning Signs of Potential Cliff Failure:

Relatively steep or over vertical cliffs
Cliffs that are undercut, where they are cut away at the bottom from wave activity Cracks in the cliff face or cliff top
Fresh debris at the bottom of a cliff. Cliff failures can be active for days, weeks, or even months. If you see fresh debris at the bottom of a cliff, stay away
June 6, 2022 Item 13
As California Cliffs Erode, UC San Diego Team Works to Track and Understand these Changes 6/3/22, 10:42 AM https://ucsdnews.ucsd.edu/feature/as-california-cliffs-erode-uc-san-diego-team-works-to-track-and-understand-these-changes Page 4 of 7 Adam Young and Lucian Perry conduct a truck-based LiDAR scan of the cliffs at Torrey Pines State Beach.

Brian Woodward with the Coastal Processes Group at Scripps conducts a survey at Torrey Pines State Beach. Here they are tracking the beach cobble to better understand how the rocks on the beach build up and retreat, and potentially act as a barrier to coastal erosion. Photo by Erik Jepsen/University Communications.
sensor. This results in a centimeter-scale resolution point cloud map of the cliff face, beach elevation and beach
cobble—the smooth rocks that are often found on San
Diego beaches in the winter.
“Each LiDAR survey provides a snapshot that we compare
to previous surveys, to measure and track erosion over
time,” said Young. “We use these surveys to quantify the erosion processes, identify erosion patterns on cliffs and beach, and examine stability conditions. The LiDAR surveys allow us to examine the site conditions before and after a landslide and help inform coastal management.”
High tides, large surf, wave run up, groundwater intrusion, rainfall, weathering and sea-level rise can all contribute to beach and cliff erosion. Young and Zumberge are hoping to gain a better understanding of the complex processes that lead up to cliff failures.

Better understanding this interplay may help answer the question of whether signals exist that can forecast where and when an increased risk for collapse is developing. If these signals exist, they would be foundational to informing recommendations towards the development of a potential early landslide warning system also envisioned in the AB 66 bill.

The second phase of AB 66, which is still awaiting permitting approval, would also see the installation of optical-fiber strainmeters at key locations along the cliffs. The strainmeters, which were also developed at Scripps for earthquake research, can measure earth movements at the scale of nanometers.

The strainmeters would be installed by embedding a fiber cable near the cliff top. The quarter-inch cable “uses light as a measuring tape,” according to Wyatt, to capture any strains of movements in the ground, sampling as quickly as 50,000 times per second.

June 6, 2022 Item 13
As California Cliffs Erode, UC San Diego Team Works to Track and Understand these Changes 6/3/22, 10:42 AM https://ucsdnews.ucsd.edu/feature/as-california-cliffs-erode-uc-san-diego-team-works-to-track-and-understand-these-changes Page 5 of 7 Any movement detected is measured instantly, creating a record similar to that from an earthquake seismograph. These important measurements may help identify small ground movement signals that precede a large cliff failure event.

These innovations are part of a suite of instruments helping oceanographers and geologists project the future of California’s coastline in an era of changing climate. Other programs that complement this research include the Coastal Data Information Program at Scripps, which generates wave model forecasts that can help estimate how waves may interact with the coastline, and the Resilient Futures program, which works with the City of Imperial Beach to provide enhanced flood forecasting to help the community better prepare for sea-level rise.

LiDAR scanning creates high resolution spatial maps of the cliff face and beach elevation. These two maps show scans of Torrey Pines colored by elevation (green being lower and red higher elevation), and in true color. The 3D model shown here is made up of more than 11 million data points. Comparing these models over time allows scientists to measure the volume of cliff or beach that has eroded. Photo credit: Coastal Processes Group at Scripps.

June 6, 2022 Item 13
As California Cliffs Erode, UC San Diego Team Works to Track and Understand these Changes 6/3/22, 10:42 AM https://ucsdnews.ucsd.edu/feature/as-california-cliffs-erode-uc-san-diego-team-works-to-track-and-understand-these-changes Page 6 of 7 The beaches in San Diego County are among the most studied in California. Routine beach surveys conducted by Scripps using all-terrain vehicles and GPS date back more than twenty years. The newer mobile LiDAR surveys provide improved coastal coverage including the cliffs and other coastal features. The surveys have expanded over time thanks to advances in technology and increased demand for this critical research to understand threats to infrastructure. The new truck- and dronebased mobile data collection have facilitated higher frequency repeat surveys and are proving critical to better understanding coastal processes.

The California coastline is home to significant and costly infrastructure on the coastline, including homes, railways, highways, wastewater treatment plants, military facilities, power plants and more. The railway corridor connecting San Diego to Los Angeles runs along the beach-top bluffs, with closures and service disruptions following cliff failures. There are calls to relocate the tracks off the bluffs, estimates of which could cost several billion dollars.
“By better understanding how the coastline is evolving now, we can make better predictions for the future,” said Young.

June 6, 2022 Item 13
As California Cliffs Erode, UC San Diego Team Works to Track and Understand these Changes 6/3/22, 10:42 AM https://ucsdnews.ucsd.edu/feature/as-california-cliffs-erode-uc-san-diego-team-works-to-track-and-understand-these-changes Page 7 of 7 The Scripps Coastal Processes Group conducts a LiDAR survey in Del Mar following a cliff collapse next to the rail corridor in February 2021. Photo credit: Coastal Process Group at Scripps Institution of Oceanography.

June 6, 2022 Item 13
1 Melinda Gould
From: Al Tarkington <[email protected]>
Sent: Saturday, June 4, 2022 8:46 AM
To: Dwight Worden-Private; dave drucker; Terry TG. Gaasterland; Tracy Martinez; Dan Quirk Cc: City Clerk Mail Box; Ashley Jones
Subject: June 6 Council Meeting , Item XI, 13 SANDAG Presentation Attachments: Coastal Commission June8, 2022.docx
Follow Up Flag: Follow up
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Dear City Council Members,
At your June 8 Council meeting, you will have a presentation from SANDAG regarding the Del Mar Bluffs. You have only two days to respond before SANDAG presents their Bluff Proposal to the California Coastal Commission on June 10.

Only two days! The timing alone should set off alarms and is an indication of SANDAG's efforts to repress comment and criticism from the Del Mar City Council.

A number of Del Mar citizens, the Surfrider Foundation and others are making presentations and submitting comments at the June 10 Coastal Commission meeting
I hope that you, our Del Mar City Council will take action and express your concerns at the Coastal Commission meeting.

I have attached my Presentation to the Coastal Commission, and I hope you will take a few minutes to read it.

Thank you,
Al Tarkington
1 June 6, 2022 Item 13
California Coastal Commission Meeting
Wednesday, June 8, 2022

7. FEDERAL CONSISTENCY
b. CC-0005-21 (San Diego Association of Governments, San Diego Co.) Coastal Commission Presentation
By Al Tarkington, former mayor of Del Mar
First, thank you SANDAG staff for your extensive and thorough Bluffs Stabilization Project 5 report. And thank you Coastal Commission staff for your Recommendations. And thank you Commissioners for your review of this extensive 91 page document.

I do have what I believe to be constructive comments on the report.

Given a target date of 2035 (23 years from now) to remove the tracks from the bluff, and a 30-year life of the project, some of the proposed plans seem unnecessary or could be revised.

First, why a 10-foot seawall for the entire 1.6-mile length? The natural bluff base from 11th Street to 7th Street is more appropriate than any seawall. Judging from photographs taken in 1885 and later, the bluff erosion has been much less than the 0.4 and 0.6 feet per year mentioned on page 59.

Judging from the old 1885 pilings, the erosion rate is one-half of SANDAG’s calculations. That makes seawalls unnecessary using the 30-year project life and the projected time to move the tracks. We should let nature run its course. With a simple 4 ft timber seawall at 11th Street, the bluff has remained unchanged since 1885! The recent seawalls are unnecessary, and they are an eyesore. Furthermore, SANDAG points out the inevitability of graffiti on the seawalls (7.a.) NCTD already has a graffiti problem along their railroad right of way in Del Mar.

In areas where the toe of the bluff is closer to the tracks, rather than a 10-foot timber wall, the California Coastal Commission should require SANDAG to construct a sand/cement barrier that is designed to slowly wear away over some reasonable (35 year?) time. The sand/cement barrier is relatively pleasing and more natural looking in comparison with the ugly 10-foot timber walls. The Coastal Commission has required this type of a barrier for numerous ocean-front properties along the California coast.

The SANDAG proposal is 10-foot vertical walls that will accelerate the backwash and will carry away the sandy beach.

The winter sand beach below is an important resting place for migrating birds. It provides a critical food source for plovers, sandpipers, curlews The gnatcatcher may not need the sand, but our shorebirds do.

There are examples along the California Coast where artificial toes at the base of the bluff are designed to minimize the backwash of high tides and surf. That could be part of a sand/cement barrier in Del Mar.

The 10-foot timber walls will be a symbol of government gone astray until they are removed in 35 years or so. The seawalls that have been installed are being called the ugliest mistake on the California Coast.

The SANDAG plan also calls for RipRap to be installed behind the timber walls. Why bring in imported rock boulders that you plan on removing in 35 years? Why not backfill with compacted soil material that will retain the natural character and will blend in with the bluffs? As with other coastal projects, some hardening material could be added to extend the lifespan. And, at the end of 35 years, the soil material will simply wear away. There would be no need to haul away RipRap.
2 June 6, 2022 Item 13
RipRap is inconsistent with Coastal mandates (Para III Conditions 1.a.) and interferes with public beach access.

Compacted soils would comply with the Commission’s Condition Seven.

I want to thank the CCC and SANDAG for a commitment to replace sand lost. However, rather than accepting a $979,625 Mitigation Fee for loss of sand (page 40), modifications of their seawalls would make a much better solution.

Improvements to Powerhouse Park (page 41) and (53) is not realistic mitigation for the loss of 130 years of public access along the blufftop.

If what I am suggesting could not be done, I would say put up the walls, put up the riprap. However, my suggestions are reasonable, they are practical, they may even be more affordable. And they are in line with the mandate of the Coastal act.

My last point. It makes no sense, from a design perspective, from timing perspective or a financial perspective to treat the pedestrian access separately from work on the bluff. SANDAG already has “conceptual plans” (page 38) in their ongoing Coastal Connections Study to be completed in the fall of 2022.

This project is all one in the same. Pedestrian trails and bluff stabilization. Please do not separate them. The trails were on the bluff and beach twenty-five years before the train tracks were moved to the bluff edge. The pedestrian access must be top priority.

NCTD has constantly rejected public pedestrian access. And it appears they will continue to prevent access. We must make the pedestrian access the same priority as the bluff work. Any form of mitigation in lieu of Public Access must be a non-starter.

Thank you for your time,
Al Tarkington
Former mayor of Del Mar
For your reference I have included historic photos of
11th Street Beach Access and Seawall History
11th Street Beach Access and Seawall History
With periodic destruction of 1885 footpath to beach by railroad stabilization work 1960? 4-foot timber seawall built by ATSF
1965? Concrete storm drain (1910) replaced by corrugated pipe 1972? Timber, approximately 18 inches added to top of existing seawall 1977 Repair to corrugated steel storm drain
1980? Riprap added in front of and behind seawall
1998 Soil Cement buttress, replace drainage outfall
2020 New 8-foot timber seawall built in front of old seawall. 2022 Proposed Seawall extension and RipRap eliminating beach access at 11th Street 3 June 6, 2022 Item 13

Old bathhouse pilings from 1885 (1977 photo)
Tarred 4 foot timber seawall (1960’s) with lighter 1972 addition

Beach Pavilion between Sea Orbit Lane and 11th Street in 1885 Compare pilings in front of Pavilion with 1977 photo. Little erosion in 90 years. 4 June 6, 2022 Item 13
1998 Soil Cement buttress, replacement of drainage outfall Footpath cut off by 1998 buttress. Buttress is “capped by soil”. Part of buttress exposed 5 June 6, 2022 Item 13
2020 photo with new 8-foot wall.
2022 SANDAG simulation of proposed Seawall extension and new RipRap at Sea Orbit Lane and 11th Street 6 June 6, 2022 Item 13
1 Melinda Gould
From: Camilla Rang <[email protected]>
Sent: Sunday, June 5, 2022 4:46 PM
To: City Clerk Mail Box
Subject: In regards to wording on agenda item 13, meeting 06.06.2022 Follow Up Flag: Follow up
Flag Status: Flagged
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Dear City Council,
I just read the agenda a little more thoroughly for item 13 (Sandag) on City Council meeting for 06.06.2022. I am deeply concerned over the wording your chose under "Discussion". It goes against everything we have been are are fighting for. Please withdraw the agenda and remove the following sentence on page 234: "Per federal law, as a rail project, this project is not subject to the Design Review Ordinance, nor any City review process." This is exactly what we are fighting AGAINST.

Quote from agenda:

DISCUSSION: SANDAG is making this presentation to the City Council as a courtesy to report on how the design for DMB5 has evolved to incorporate prior feedback from the City. Per federal law, as a rail project, this project is not subject to the Design Review Ordinance, nor any City review process. The only exception would be an Encroachment Permit for use of the public right-of-way for either permanent elements of the project or temporary construction activities.

Best,
Camilla Rang
1 June 6, 2022 Item 13
1 Melinda Gould
From: Laura Walsh <[email protected]>
Sent: Monday, June 6, 2022 12:00 PM
To: City Clerk Mail Box
Cc: Terry TG. Gaasterland; Dwight Worden-Private; Mitch Silverstein; David Druker; [email protected]; [email protected]
Subject: Red Dot Monday June 6 Regarding SANDAG DMB5 Informational Presentation Attachments: Surfrider _ Red Dot_Del Mar _DMB5.pdf; Surfrider DMB 5 Coastal Commission Letter.pdf Follow Up Flag: Follow up
Flag Status: Flagged
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Good afternoon members of Del Mar City Council —
Surfrider would like to submit the following Red Dot in response to the Informational Presentation at today's City Council meeting. We are also submitting our recent letter to the Coastal Commission on the upcoming DMB5 federal consistency determination as an attachment.

Thank you for the opportunity to weigh in on this important project.

Best,
Laura W.
--
Laura Walsh | California Policy Manager | Surfrider Foundation | she/her/hers 702.521.8196 | [email protected]
1 June 6, 2022 Item 13
June 3, 2022
To: Donne Brownsey, Chair, California Coastal Commission Cc: John Ainsworth, Executive Director, California Coastal Commission Re: Item W7b, CC-0005-21 (San Diego Association of Governments, San Diego Co.) Dear Chair Brownsey and Commissioners,
The Surfrider Foundation (Surfrider) is a nonprofit grassroots organization dedicated to the protection and enjoyment of the world’s ocean, waves and beaches, for all people, through a powerful activist network. Our San Diego Chapter is deeply involved in railroad protection and relocation issues in Del Mar. We have also been engaged in state and local decisions related to previous phases of Del Mar Bluff Stabilization (DMB) work, as well as more recent local conversations related specifically to DMB Phase 5.

Surfrider San Diego County is a member of the Los Angeles – San Diego – San Luis Obispo (LOSSAN) Regional Rail Corridor Working Group and the San Diego Shoreline Preservation Committee. We were part of Del Mar’s Sea Level Rise Technical Advisory Committee that led sea level rise discussions related to Del Mar’s Local Coastal Program Update process beginning in 2015. Our comments on DMB5 are consistent with our goal to see Del Mar plan for sea level rise to protect coastal access, coastal recreation, and marine resources in the most effective way, given current conditions affecting the safety and operability of the railroad.

We support the staff recommendation to make a conditional consistency determination for this project, but propose a number of critical suggestions to meet the needs of this community given the proposed project’s extreme impacts.

Surfrider recognizes the need to stabilize the Del Mar section of the LOSSAN corridor and appreciates that the San Diego Association of Governments (SANDAG) and Coastal Commission staff have worked hard to reduce project impacts.

However, we cannot overstate the impact of this project to Del Mar’s beaches and bluffs.

Anticipated impacts can be found inconsistent with Sections 30251, 30253, and the access policies of chapter 3 of the Coastal Act (at a minimum) unless proper conditions are accepted in the Consistency Determination.

Del Mar’s special bluffs, beaches, and waves are cherished by locals and visitors from throughout San Diego County, the State of California, and the country. Certain aspects of DMB5 — like the upper bluff stabilization, which can never be undone — will degrade the natural coastline in one of Southern California’s quintessential beach towns far beyond the lifetime of this permit. Any permit extensions will also perpetuate related impacts. 2 June 6, 2022 Item 13
Executive Summary
● To meet the specifications of Coastal Act Section 30253 and ‘mitigate’ damage, the project must facilitate relocation of the railroad.
● We recommend a number of suggested amendments to support relocation that are aimed at clarifying intentions to remove the proposed ½ mile of seawall. ● We support the staff report in pursuing a project design based on low-risk sea level rise scenarios because this supports the commitment to relocate the tracks. ● SANDAG has not provided environmental documentation to support a thorough analysis of the project proposal. The Commission should maximize public access opportunities so that the mitigation proposal is consistent with the access and recreation policies of Chapter 3 of the Coastal Act.
● We support the Capital Improvement Projects (CIP) proposed and recommend safe crossings at both 7th and 11th street. These projects are critical for securing access in spite of construction, proposed fencing, and armoring and should not be scaled back under any circumstance.
● The vertical access trails should benefit from a long-term rail to trail program. ● We recommend interim public access projects on Torrey Pines State Beach to address the seven year or more gap during which the CIP projects are not completed. ● The wetland mitigation ratio should be 4:1. The .28 acres of wetland habitat affected by this project are some of the last remaining intact wetlands in California. ● We request clarity around where and when rolling construction takes place so the schedule can be clearly understood by the community.
3 June 6, 2022 Item 13
This project is devastating to Del Mar’s bluffs and beaches Approval of this permit includes the authorization of half a mile of seawall (2,500 feet) for 30 years, the permanent grading and upper bluff stabilization of approximately three quarters of a mile of bluff, and the construction of at least five stormwater outfalls.

Related impacts include:
● Construction activities taking up beach space and blocking access on Del Mar and State Park beaches for as long as three years. This impact could be found to be inconsistent with Sections 30210, 30211, 30212, 30220, 30221 of the Coastal Act and Section 4 of Article X of the California Constitution.
● Loss of beach access at 7th and 11th Street for up to seven years — or longer if other agencies do not comply with permit terms. This impact could be found inconsistent with Sections 30210, 30211, 30212, 30220, 30221 of the Coastal Act and Section 4 of Article X of the California Constitution.
● Narrowing of large stretches of beach and disappearance of lateral access along the beach caused by the placement of seawall and rip rap backfill for up to 30 years, with permanent narrowing of the beach expected in the future due to accelerated erosion and sea level rise. This impact could be found inconsistent with Sections 30210, 30211, 30212, 30220, 30221 of the Coastal Act and Section 4 of Article X of the California Constitution.
● Permanent loss of habitat along natural bluffs and on beaches, with temporary loss guaranteed during three years of project construction. This impact could be found inconsistent with Section 30240 of the Coastal Act.
● Drastic visual change to the bluffs, particularly due to the seawall visible to all beachgoers including surfers and boaters in the water for up to 30 years.This impact could be found inconsistent with Sections 30251 and 30253 of the Coastal Act. ● Potentially increased erosion, water quality contamination, and rip currents caused by the construction of five stormwater outfalls. This impact could be found inconsistent with Section 30231 of the Coastal Act.
● Permanent loss of .28 acres of some of California’s last remaining wetlands.

This impact could be found inconsistent with Sections 30233, 30231 and 30255 of the Coastal Act.

In light of these major impacts, we suggest mitigation opportunities and make recommendations to ensure accountability and transparency throughout the process:
4 June 6, 2022 Item 13
The benefit of this project is that it can facilitate improved coastal access and long-term managed retreat
Surfrider can live with basic aspects of this project because it memorializes and motivates relocation of the LOSSAN railroad, which should never have been located on Del Mar’s fragile and eroding bluffs in the first place. Further explanation is in our letter to this Commission related to emergency bluff work in 2020
1 . As this staff report points out, SANDAG committed to relocating the Del Mar section of the LOSSAN corridor by 2035 (memorialized in its 2021 San Diego Forward Regional Transportation Plan) due to the fact that the rail faces increasing coastal hazards from sea level rise and erosion in the near and long-term.

Relocation of the railroad tracks provides an extremely rare and important opportunity to allow space for Del Mar’s coastline to migrate landward as sea levels rise. It will also secure public recreation, viewing, and access opportunities along the former rail corridor in the future. If successfully managed, this project will be a nationally significant case study, where today’s permit represents one step along an adaptation pathway towards managed retreat of critical infrastructure and restoration of an otherwise highly developed area onan eroding shoreline.The site is unique in San Diego County as one of the few areas along coastal bluffs where existing development would no longer be threatened once the rail is relocated.

This project can be found consistent with the Coastal Act, the Coastal Commission’s Sea Level Rise Guidance, and the Coastal Commission’s Guidance on Critical Infrastructure only insofar as it facilitates relocation and provides mitigation for both short and long term access impacts.

It is obvious that this project contravenes many Coastal Act policies, including 30253 and 30251, as well as access policies in Sections 30210, 30211, 30212, 30220, 30221 of the Coastal Act and Section 4 of Article X of the California Constitution.

The justification for the project rests on the provision of Coastal Act Section 30235, which allows the Coastal Commission to permit armoring “when required to serve coastal-dependent uses or to protect existing structures or public beaches in danger from erosion, and when designed to eliminate or mitigate adverse impacts on local shoreline sand supply.” However, Section 30253(2) of the Coastal Act requires that new development shall not contribute to erosion nor “require the construction of protective devices that would substantially alter natural landforms along bluffs and cliffs.” While hard structures provide temporary protection against the threat of sea level rise, they disrupt natural shoreline processes, accelerate long-term erosion, cause loss of beach and other critical habitats and corresponding ecosystem benefits, as well as impair beach access and recreational uses. Therefore, armoring must be avoided or, in this instance, used for a minimized and time-certain duration. 1 https://documents.coastal.ca.gov/reports/2020/8/W13b/W13b-8-2020-correspondence.pdf 5 June 6, 2022 Item 13
Relocating the train is a practical way of meeting the requirement to mitigate adverse impacts of this project, and SANDAG has already committed to this intention in its Regional Transportation Plan.

In order to facilitate rail relocation, critical adjustments to the staff report need to be made in order to ensure accountability and feasibility — we make those suggestions in later sections of this letter. We note here however that the goal of managed retreat is both ambitious and imperative, and we generally support staff in their assumption that retreat will be achieved by 2035 with flexibility through 2053 (which captures the 30 year permit timeline.) Because of this permit timeline, Surfrider concurs with staff that in this particular instance, SANDAG should not be held to design this critical infrastructure project to meet the standards of the H++ risk aversion sea level rise scenario. We take note that the Commission’s Sea Level Rise Guidance recommends analyzing critical infrastructure under the medium high-risk aversion and extreme-risk aversion scenarios because of its typically long design life, low adaptive capacity, and the high consequences associated with its failure; all of which apply to this project. While we strongly agree with this concept generally, the added variable of SANDAG’s commitment to relocate the train drastically shortens the otherwise long design life of this type of project. We agree that a 1 in 20 and low-risk aversion scenario is more appropriate when the design life of the project is the next 30 years, as this allows for a calibration of the project design that reduces impacts to coastal resources and coastal access while still managing risk.

We do also note that it is important to interpret the Commission’s Sea Level Rise Guidance 2 in
context. The Guidance provides that the Commission must consider critical infrastructure projects on a case-by-case basis, and that projects that facilitate relocation are preferred:

Chapter 7: Adaptation Strategies includes a goal regarding special considerations for protecting transportation infrastructure which states that applicants should:
“Develop or update a long-term public works plan for critical facilities to address sea level rise: Develop a long-term management plan to address the complexities of planning for sea level rise that incorporates any potential maintenance, relocation, or retrofits and structural changes to critical facilities to accommodate changes in sea level, and obtain Coastal Commission certification.” (page 140, California Coastal Commission Sea Level Rise Guidance)
The Guidance similarly supports incremental changes to transportation networks specifically to facilitate realignment:
2 https://documents.coastal.ca.gov/assets/slr/guidance/2018/0_Full_2018AdoptedSLRGuidanceUpdate.pdf 6 June 6, 2022 Item 13
“Allow for phased implementation of realignment and relocation projects: In some cases it may be necessary to make incremental changes in transportation networks so that access to and along the coast can be maintained while also addressing coastal hazards over the long-term” (page 141, California Coastal Commission Sea Level Rise Guidance)
We strongly support the staff report in working towards its own adopted SLR Guidance and memorializing the legally binding aspects of SANDAG’s policy commitment to relocate the Del Mar section of the LOSSAN corridor by 2035.

Environmental documentation is missing
The Staff Report notes that DMB5 is categorically exempt from the NEPA and CEQA process.

Additionally, SANDAG has made clear that there is a pressing need to embark on this project before the next rainy season, given the bluff failures that have resulted in emergency work in recent years.

While Surfrider notes the intense efforts and collaboration that have been pursued to achieve the proposal outlined in the staff report, we note the following as important environmental documentation that is noticeably not part of the report:
● Identification of an environmentally superior alternative - Including potentially an entirely different alternative; perhaps one that includes a ‘phased’ component to seawall installation
● Lack of Coastal Connections Study - SANDAG has failed to complete the Coastal Connections Study within the timeframe provided by its DMB Phase 4 permit. This staff report is therefore unable to include information about the public access projects being proposed in this project, which would otherwise help determine whether or not appropriate public access mitigation can be provided on a reasonable timeline. ● Risk assessment information justifying the location, extent, and needed timing of stabilization measures - Currently SANDAG appears to be justifying the accelerated timeline of the project on the fact that recent bluff failures have occurred in areas that were previously identified as ‘low risk.’ This broad swath approach to stabilizing the entire bluff is reactive and most likely over-assumes risk in certain areas, which will ultimately come at the consequence of coastal resources and coastal access.

Without these environmental documents, it is extremely difficult for Surfrider and the Commission to determine whether or not the current proposal represents the least environmentally damaging and feasible alternative. It is also difficult to determine whether the proposed mitigation, monitoring and reporting efforts are sufficient. 7 June 6, 2022 Item 13
In light of these missing environmental documents and analysis, we submit that the most important step the Commission can take to finding Coastal Act consistency in this case is to secure maximum reasonable mitigation opportunities for this enormously consequential project.

Below, we suggest mitigation opportunities and make recommendations to ensure accountability and transparency throughout the process.

Recommendation #1 - Make adjustments to support relocation As has been discussed, this project can only meet Coastal Act requirements and the Commission’s Sea Level Rise Guidance requirements by reaffirming SANDAG’s already formal commitment to relocation of the Del Mar Section of the LOSSAN corridor by 2035. We suggest the following adjustments:
1a. Staff Report Language on Relocation and Automatic Extensions - We ask that staff make a minor adjustment to the report so as not to undermine SANDAG’s commitment to relocate the track by 2035. It is possible to justify the 30-year permit timeline without undermining SANDAG’s formal policy language in its RTP. For instance, the discussion on page 10 of the staff report states:
“SANDAG is currently in the process of planning to relocate the tracks consistent with the regional transportation plan; however, given the magnitude and complexity of that effort and outstanding funding needs for final design, environmental review, and construction, implementation of the relocation would likely extend beyond the target date of 2035.”
This should be amended to replace the phrase ‘would likely’ with ‘may,’ at a minimum. We suggest further amendments to acknowledge the difficulty of relocation, while adding language such as the below:
“However, SANDAG has made a formal commitment in its Regional Transportation Plan that commits the agency to relocating this rail by 2035.” Surfrider also has concerns with the potential for undue delay given the automatic extensions currently granted in the conditional approval. Surfrider suggests the report implement a condition that addresses authorization term without allowing for automatic extensions upon application submission so that the project is not unduly delayed. We appreciate that Condition One otherwise memorializes the commitment to relocate the track by 2035. 1b. Removability of Seawalls - The removal of the seawalls permitted in this project is a critical step towards relocation, which allows for mitigation of lost public access and recreation. We make the following recommendations to strengthen the requirements for removable seawalls:
8 June 6, 2022 Item 13
● Adjust conditions on authorization terms to remove rail abandonment aspects. Condition 1a states that the authorization of seawalls included in the consistency certification shall expire in 30 years or upon relocation and legal abandonment of the sections of railroad at issue in this action, whichever occurs first. We suggest amending this language to require the seawalls to be removed after 30 years or when the rail line is no longer in service. The North County Transit District (NCTD) may never formally abandon this section of rail — for instance NCTD still leases portions of its property to the City of Del Mar near the Del Mar Fairgrounds, though that area has not received rail service in decades. This condition should also clarify that the legally permitted purpose of the seawall may only pertain to bluff stabilization as long as rail service continues. ● Clarify whether the current seawalls will also be removed as part of the project. Surfrider assumes that the temporary and emergency seawalls that have been constructed by SANDAG through previous permits will also be removed when the rail is no longer in service. Removal of these seawalls will also be necessary to achieve the goals of a larger managed retreat effort. This should be clarified through Authorization Term conditions.
● The Commission should add a condition that the seawall is constructed only to protect the railroad and any other existing or future development cannot rely on the permitted seawall to establish geologic stability. Failure to include this type of special condition may result in SANDAG or other property owners claiming that continued authorization of the seawalls is necessary to accommodate existing or additional development. ● The Commission should add a requirement that SANDAG work with the City of Del Mar to develop a formal notification procedure to inform current and future blufftop property owners that the seawalls are temporary and will be removed by the end of the permit term. This will serve to negate any legal takings claims when the seawalls are scheduled for removal and prohibit any future claimed reliance on the seawalls to protect private property.
● The Commission should consider an opportunity to delay seawall construction as long as possible. Surfrider understands that the various components of the stabilization project (upper bluff stabilization, bluff toe stabilization, and other irrigation efforts) all work together, but bluff toe stabilization specifically manages wave overtopping caused by storm surge that is exacerbated by sea level rise. It is unclear whether or not the current seawall designs are necessary to meet today’s erosion impacts to the bluff toe. If the seawalls are designed to mitigate risk that is forthcoming, then the seawalls can be permitted today with an agreement about a phased, trigger-based installation at a later date. This would reduce the impacts of the seawall on erosion, which will immediately extend the back of the beach seaward on some parts of the beach and compound erosion and access issues over time.
9 June 6, 2022 Item 13
● The Commission should include a condition that SANDAG work with Scripps Institution of Oceanography to employ advanced geophysical instruments and utilize the data from their coastal LiDAR surveys to track bluff erosion and monitor slope stability at the site.

Recommendation #2 - Adjust public access mitigation proposals to be consistent with access and recreation policies of Chapter 3 Surfrider appreciates the capital improvement projects that have been suggested in the staff report. In particular, safe crossings at 7th Street and 11th Street as well as vertical access trails would be an improvement to the current situation of unsafe and insecure access to the walkable beach and enjoyable waves in the area.

We agree generally with staff that it is not possible to ‘buy back a beach’ in this area to provide in-kind mitigation for the dramatic impacts that this project will have on beach erosion and lateral beach access, as well as both vertical and lateral access throughout construction. If public access mitigation is the only available form of mitigation as in-kind mitigation is not possible, and if the project is missing necessary documents (as described above) that would be required to fully find Coastal Act Consistency, the Commission should seek to maximize public access as mitigation.

In the past, mitigation for seawall impacts over time was provided by payment of recreation fees to account for lost beach area.
3 Similar fee programs should be considered, perhaps for an endowment fund to manage the vertical trails (mentioned later). In contrast to previous fee programs that only mitigate for lateral access and placement loss, the DMB5 project must also mitigate for additional loss of vertical beach access from the blufftop to the beach and for lateral access along the beach. In order to address these impacts, additional mitigation is required to meet the nexus test of the impact. Simply rebuilding existing vertical access while access is lost for many years does not mitigate all impacts commensurately. Both vertical and horizontal access must be mitigated in the short and long term in order to meet the nexus tests of the Nollan and Dolan cases
4 .

We note that even the current staff recommendation affords SANDAG up to seven years to complete the proposed capital improvement projects. Given that these projects may hinge on approvals from the North County Transit District and California Public Utilities Commission, it could take even longer. It is unreasonable that the City of Del Mar and the over 2 million annual Del Mar beach visitors should fail to benefit from public access mitigation for seven years or more. We suggest the following adjustments to help mitigate this scenario and provide further suggestions for mitigation opportunities:
4 See Nollan v. California Coastal Comm'n, 483 U.S. 825, 107 S. Ct. 3141, 97 L. Ed. 2d 677 (1987) and Dolan v. City of Tigard, 512 U.S. 374, 114 S. Ct. 2309, 129 L. Ed. 2d 304 (1994). 3 See for example Land Use Plan (LUP) Amendment #LCP-6-SOL-16-0020-1 (Public Recreation Fee), CDP 6-05-072/Las Brisas Recreation Fee and CDP 3-02-024/Ocean Harbor House. 10 June 6, 2022 Item 13
1 - Strengthen mitigation project opportunities. The capital improvement projects suggested in the report are critical for securing access in spite of construction, proposed fencing, and armoring. These projects should not be scaled back under any circumstance. To maximize the benefits of public access mitigation, we strongly urge the Commission to require vertical access and safe crossings at both 7th and 11th Street - not one or the other. Both of these are currently popular accessways that facilitate surfing, walking, and beach enjoyment over more than a mile of beach. There is a recognized surfing reef at 8th St. in Del Mar and 11th St. offers a unique peak as well.
2 - Include interim project opportunities in addition to the capital improvement projects. Much of the staging for this project occurs on Torrey Pines State Beach, and no public access mitigation has been suggested in this staff report. Surfrider suggests working with State Parks to make two public access improvements to Torrey Pines, which would provide some mitigation for State Parks access and possibly address the 7 year or more gap in which SANDAG could fail to provide access.
2a. Project #1 - We suggest working with State Parks on a project concept to create a living shoreline near the highbridge between Los Penasquitos Lagoon and Torrey Pines State Beach.

The maintenance of the beach under the bridge is important for visitors coming from the North Torrey Pines parking lot, and is a valued access point for on duty lifeguards and for Junior Lifeguards practice. The beach in this area is vulnerable to high tides because of its location near the lagoon, the local geomorphology, and the fact that the substrate (which is fill from the historic rail construction) is very soft. In the past, State Parks has maintained the beach by inlet dredging but this area is a good opportunity for a more resilient living shorelines project with cobble toe. Funding is needed to haul the sand and cobble from the lagoon and would also assist with annual planned inlet maintenance. Such a project would make the area more resilient, provide critical public safety and public recreation access, provide an access point for Rail ROW maintenance and repair, and be designed to maximize habitat and resilience. It could also be completed in the near term and serve as a multi-benefit coastal resilience pilot project in the City of San Diego.
2b. Project #2 - State Parks has also identified three areas along Torrey Pines Road where a staircase would be useful for facilitating public access to the beach. This section of the beach is often physically separated from the southern part of the beach when the lagoon is breached.

People who are trying to cross to the other section of beach, or who parked in the parking lot near the lagoon, would be able to access the beach considerably quicker than is currently possible. At least one option for a staircase in this area would not require armoring and would provide faster access to the beach for public safety and maintenance staff. This project could also potentially integrate with the City of San Diego’s goals to construct an ADA beach access in the area.

3. Require SANDAG to report on CPUC and NCTD successes - The safe crossings at 7th and 11th Street will require California Public Utilities Commission (CPUC) and NCTD approval, where approval could fail to be provided or extend the timeline of this project. The Coastal 11 June 6, 2022 Item 13
Commission should hold SANDAG to account in making a robust effort to secure these approvals. We recommend including a condition requiring SANDAG to show and report on robust efforts to secure approvals from both of these agencies.

4. Ensure that public access benefits remain after project is gone. The staff report is unclear on what will happen to the vertical accessways once the permit expires and the seawalls are removed. Surfrider supports maintaining these accessways even while a larger relocation effort is pursued. We recommend SANDAG be required to implement a formal rail to trail program, which would perhaps set up a process for transferring ownership such as through the establishment of an endowment fund that the City of Del Mar, State Parks, or some other entity could use to assume management of the trails in the future.

Recommendation #3 - Adjust wetland mitigation
The .28 acres of wetland habitat affected by this project are some of the last remaining intact wetlands in California. They are home to endangered species and habitat to native flora and fauna, and they provide carbon sequestration benefits. In a May 26th SANDAG presentation to the City of Del Mar Design Review Board, a statement was made by SANDAG that impacts to ospreys are not a concern and that they feed in the San Dieguito lagoon. This is inaccurate.

Ospreys, peregrine falcons, crabs, and many other species use the tidal zone for feeding.

It is also unclear why staff has chosen a 1:1 mitigation ratio for wetlands when it is more common to use a ratio of 4:1. We suggest a minimum 4:1 ratio based on the Commission’s own Procedural Guidance for the Review of Wetland Projects in the California Coastal Zone, which states that a “wetland mitigation ratio in excess of one to one” should be used and that a higher mitigation ratio helps to compensate for wetland acreage and functional capacity lost at the specific site. Given that the recommendation is fee-based, we recommend applying this funding to the suggested project at Torrey Pines, which affects the Los Peñasquitos Lagoon.

Recommendation #4 - Communications for transparency
We suggest making some adjustments to better communicate the impacts of this project to community members. In particular, we suggest clarifying:

The project construction timeline - We are under the impression, but it is not clear from the staff report, that construction will occur on a rolling basis to address areas marked in the staff report as high priority, then medium, then low. SANDAG should be required to clarify which sections of the bluffs are being worked over time, and this information should also be stated in the staff report.

Project endurance - It is not stated anywhere in the staff report that the upper bluff stabilization is, in fact, permanent. This is of significant consequence to those who care about the natural features of the bluff. This should be stated clearly in the report. The state of the soldier piles, 12 June 6, 2022 Item 13
connecting grade beams at the surface and tie backs as they become exposed should also be further discussed.

Conclusion
Thank you for your consideration of these requests. We hope to see coastal resources and access recovered in Del Mar in the long-term upon inclusion and consideration of these permit adjustments for finding conditional concurrence for Coastal Act consistency.

Best,
Laura Walsh,
California Policy Manager
Surfrider Foundation
Mitch Silverstein
Policy Manager
Surfrider Foundation San Diego County
Jim Jaffee
Beach Preservation Co-Lead
Surfrider Foundation San Diego County
Kristin Brinner
Beach Preservation Co-Lead
Surfrider Foundation San Diego County
Udo Wahn
Climate Co-Lead
Surfrider Foundation San Diego County
13 June 6, 2022 Item 13
June 6, 2022
Re: SANDAG PRESENTATION REGARDING DEL MAR BLUFF STABILIZATION PHASE 5 Dear Members of the Del Mar City Council -
The Surfrider Foundation (Surfrider) is a nonprofit grassroots organization dedicated to the protection and enjoyment of the world’s ocean, waves and beaches, for all people, through a powerful activist network. Our San Diego Chapter is deeply involved in railroad protection and relocation issues in Del Mar. We have also been engaged in state and local decisions related to previous phases of Del Mar Bluff Stabilization (DMB) work, as well as more recent local conversations related specifically to DMB Phase 5.

Surfrider San Diego County is a member of the Los Angeles – San Diego – San Luis Obispo (LOSSAN) Regional Rail Corridor Working Group and the San Diego Shoreline Preservation Committee. We were part of Del Mar’s Sea Level Rise Technical Advisory Committee that led sea level rise discussions related to Del Mar’s Local Coastal Program Update process beginning in 2015. Our comments on DMB5 are consistent with our goal to see Del Mar plan for sea level rise to protect coastal access, coastal recreation, and marine resources in the most effective way, given current conditions affecting the safety and operability of the railroad.

We submit this red dot in order to express our priorities with regard to bluff stabilization in Del Mar and to make clear our understanding of project impacts and to outline our current position on the upcoming Federal Consistency Determination at the Coastal Commission.

Surfrider recognizes the need to stabilize the Del Mar section of the LOSSAN corridor and appreciates that the San Diego Association of Governments (SANDAG) has worked hard to reduce project impacts. However, we cannot overstate the impact of this project to Del Mar’s beaches and bluffs. Del Mar’s special bluffs, beaches, and waves are cherished by locals and visitors from throughout San Diego County, the State of California, and the country. Certain aspects of DMB5 — like the upper bluff stabilization, which can never be undone — will degrade the natural coastline in Del Mar far beyond the lifetime of this permit. Any permit extensions will also perpetuate related impacts.

This project is devastating to Del Mar’s bluffs and beaches DMB5 includes the authorization of half a mile of seawall (2,500 feet) for 30 years, the permanent grading and upper bluff stabilization of approximately three quarters of a mile of bluff, and the construction of at least five stormwater outfalls.

Based on the Coastal Commission staff report for this item, we understand related project impacts to include:
14 June 6, 2022 Item 13
● Construction activities taking up beach space and blocking access on Del Mar and State Park beaches for as long as three years.
● Loss of beach access at 7th and 11th Street for up to seven years — or longer if other agencies do not comply with permit terms.
● Narrowing of large stretches of beach and disappearance of lateral access along the beach caused by the placement of seawall and rip rap backfill for up to 30 years, with permanent narrowing of the beach expected in the future due to accelerated erosion and sea level rise.
● Permanent loss of habitat along natural bluffs and on beaches, with temporary loss guaranteed during three years of project construction.
● Drastic visual change to the bluffs, particularly due to the seawall visible to all beachgoers including surfers and boaters in the water for up to 30 years. ● Potentially increased erosion, water quality contamination, and rip currents caused by the construction of five stormwater outfalls.
● Permanent loss of .28 acres of some of California’s last remaining wetlands.

The benefit of this project is that it can facilitate improved coastal access and long-term managed retreat
Surfrider can live with basic aspects of this project because it memorializes and motivates relocation of the LOSSAN railroad, which should never have been located on Del Mar’s fragile and eroding bluffs in the first place. SANDAG committed to relocating the Del Mar section of the LOSSAN corridor by 2035 (memorialized in its 2021 San Diego Forward Regional Transportation Plan) due to the fact that the rail faces increasing coastal hazards from sea level rise and erosion in the near and long-term.

Relocation of the railroad tracks provides an extremely rare and important opportunity to allow space for Del Mar’s coastline to migrate landward as sea levels rise. It will also secure public recreation, viewing, and access opportunities along the former rail corridor in the future. If successfully managed, this project will be a nationally significant case study, where today’s permit represents one step along an adaptation pathway towards managed retreat of critical infrastructure and restoration of an otherwise highly developed area onan eroding shoreline.The site is unique in Del Mar and in San Diego County as one of the few areas along coastal bluffs where existing development would no longer be threatened once the rail is relocated.

This project can be found consistent with the Coastal Act, the Coastal Commission’s Sea Level Rise Guidance, and the Coastal Commission’s Guidance on Critical Infrastructure only insofar as it facilitates relocation and provides mitigation for both short and long term access impacts.
15 June 6, 2022 Item 13
It is obvious that this project contravenes many Coastal Act policies to protect the coastline and access to it. The justification for the project rests on the provision of Coastal Act Section 30235, which allows the Coastal Commission to permit armoring “when required to serve coastal-dependent uses or to protect existing structures or public beaches in danger from erosion, and when designed to eliminate or mitigate adverse impacts on local shoreline sand supply.”
However, Section 30253(2) of the Coastal Act requires that new development shall not contribute to erosion nor “require the construction of protective devices that would substantially alter natural landforms along bluffs and cliffs.” While hard structures provide temporary protection against the threat of sea level rise, they disrupt natural shoreline processes, accelerate long-term erosion, cause loss of beach and other critical habitats and corresponding ecosystem benefits, as well as impair beach access and recreational uses. Therefore, armoring must be avoided or, in this instance, used for a minimized and time-certain duration.

Relocating the train is a practical way of meeting the requirement to mitigate adverse impacts of this project, and SANDAG has already committed to this intention in its Regional Transportation Plan.

In order to facilitate rail relocation, Surfrider has suggested amendments to SANDAG’s current plans outlined in the Coastal Commission June 2022 Staff Report. These amendments need to be made in order to ensure accountability and feasibility. We note however that the goal of relocating the rail line is both ambitious and imperative, and we generally support intentions to ensure that removal.

Executive summary of our position on the upcoming federal consistency determination at the Coastal Commission
● To meet the specifications of Coastal Act Section 30253 and ‘mitigate’ damage, the project must facilitate relocation of the railroad.
● We recommend a number of suggested amendments to support relocation that are aimed at clarifying intentions to remove the proposed ½ mile of seawall. ● We support the pursuit of a project design based on low-risk sea level rise scenarios because this supports the commitment to relocate the tracks. ● SANDAG has not provided environmental documentation to support a thorough analysis of the project proposal. Public access opportunities should be maximized so that the mitigation proposal is consistent with the access and recreation policies of Chapter 3 of the Coastal Act.
16 June 6, 2022 Item 13
● We support the Capital Improvement Projects (CIP) proposed and recommend safe crossings at both 7th and 11th street. These projects are critical for securing access in spite of construction, proposed fencing, and armoring and should not be scaled back under any circumstance.
● The vertical access trails should benefit from a long-term rail to trail program. ● We recommend interim public access projects on Torrey Pines State Beach to address the seven year or more gap during which the CIP projects are not completed. ● The wetland mitigation ratio should be 4:1. The .28 acres of wetland habitat affected by this project are some of the last remaining intact wetlands in California. ● We request clarity around where and when rolling construction takes place so the schedule can be clearly understood by the community.

More can be read in our June 3 letter to the Coastal Commission, also submitted as an attachment.

Conclusion
We hope to work with the City of Del Mar to ensure that coastal resources and access are mitigated for and recovered in DMB5.

Best,
Laura Walsh,
California Policy Manager
Surfrider Foundation
17 June 6, 2022 Item 13
1 Melinda Gould
From: City Clerk Mail Box
Subject: FW: Red dot for item 13: SANDAG Bluff Stabilization project 5 Melinda Gould
City of Del Mar | Administrative Services
1050 Camino del Mar
Del Mar, CA 92014
| 858.704-3633 | [email protected]
City Hall is open for public services Monday-Thursday, from 7:30 AM- 5:30 PM and Friday from 7:30 AM- 4:30 PM. Counter hours for Planning and Building services are Monday and Wednesday between 1:00 PM to 5:30 PM or by appointment. All remote services will continue to be provided during regular City hours. Please check our City website at www.delmar.ca.us for more information.

From: Laura DeMarco <[email protected]>
Sent: Monday, June 6, 2022 12:48 PM
To: City Clerk Mail Box <[email protected]>
Subject: Red dot for item 13: SANDAG Bluff Stabilization project 5 CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you recognize the sender and know the content is safe.

Dear Council Members and Staff,
The issues not yet addressed are the long-term costs and liabilities to Del Mar families, the city of Del Mar, and its tax base from our unstable bluffs.

The acceleration in the frequency and size of the bluff slides demonstrates the danger to life and the city’s tax base.

That’s why we cannot allow NCTD’s 6 ft fencing to add 1,000+ new points of stress from drilling 3 ft deep x 1 ft holes to install 6-ft tall wire fencing with heavy concrete footings into these crumbling bluffs.

Del Mar’s SLR committee and the City Council previously opposed the Coastal Commission’s requirement for deed restrictions on most properties in the South Bluff neighborhood. The justification was that SANDAG’s seawalls and bluff stabilization measures designed to protect the rail line also protected those properties.

It’s evidently no longer working as there have been 8 large bluff slides in the last 3 years that could have killed or injured beachgoers below. SANDAG’s bluff retreat map shows significant erosion rates, even with the proposed seawalls. When those seawalls are removed, erosion will accelerate beyond the current 6 inches/year historical average in the more vulnerable sections that protect filled-in canyons. The public beach access trails down the bluff face would eventually disappear, followed by the lower bluff trail, the upper bluff trail, and then city infrastructure and properties near the bluff as shown in the Coastal Hazards section of Del Mar’s Sea Level Rise report (see attached map of one section).

Note that the Coastal Commission requires development setbacks for the 75-year design life of a remodel or new house construction plus 40-ft from the edge of the slope. This would be enforced by deed restrictions with triggers similar to those that Del Mar opposed in the North Beach neighborhood. 1 June 6, 2022 Item 13
2 Longer-term when the rail line moves from the bluffs, Del Mar will bear all the costs for maintaining the bluff and its public access trails plus the liability for injuries and deaths from bluff slides. What are these costs, can we afford them, and how can they be reduced and public access improved by SANDAG’s project? According to SANDAG, their proposed bluff stabilization project 5 is the result of direction primarily from the city of Del Mar and the Coastal Commission. It would be helpful to clarify that SANDAG’s plans no longer include “shaving” or “decapitating” the western bluff edge berm above the tracks and the Council’s preferences, especially for soldier piles, seawalls, and other bluff protection alternatives such as sand replenishment.

Since the tall and unsightly wood-plank seawalls cannot be contoured to the bluff, they are set further west of the bluff toe onto the beach. Piles of rip rap have to be backfilled between the bluff slope and the 10 ft tall wood seawall that now functions more like a retaining wall. As a result, these wood-plank walls encroach more of the beach that is already so narrow in segments that it is not walkable at high tide.

SANDAG engineers at the farmer’s market table mentioned said they used wood-plank walls based on direction from previous city council discussions. Another alternative they discussed was a more natural rock-sculpted concrete that could be contoured to the bluff with the same coloring. This would encroach less of the beach than the wood walls.

However, they are more expensive, more difficult to remove, and taller in height than the wood walls.

The SANDAG engineers clarified that their proposed project would not block existing surfer trails at 7th and 11th St.

They showed renderings of the wood seawalls being staggered and set back to protect the trail entrances (see photos below).
2 June 6, 2022 Item 13
3 The seawalls and rip rap in these sections would help preserve the stability of the trails and footholds.

Another exhibit was a map of the entire bluff with markings showing expected bluff retreat within 30 years, their timeline for the design life of the project. Their prior bluff stabilization projects had a design life of 20 years which is why the soldier piles installed almost 20 years ago by WaveCrest failed and led to the bluff collapsing within a few feet of the tracks. SANDAG’s emergency repairs reinforced the old piles’ lateral support but their vertical support now requires a seawall/retaining wall in that area because the piles don’t extend all the way to the beach level.

The proposed new 30-year design life soldier piles will have more lagging between the piles and tie backs and be much longer as they extend all the way to the beach level. Once installed, they cannot be removed without impacting the stability of the bluff so there is no room for error in their design and construction. Has the city consulted with geotechnical engineers to review and monitor SANDAG’s project and construction plans? SANDAG’s map marked the location of drainage repairs and improved storm water channels to divert the inland water intrusion that is one of the primary cause of bluff failures. The southern sub drain collects groundwater from a 60-acre catchment area extending from the bluffs to Crest Rd. and Nogales Drive at the top of Del Mar Heights. Groundwater currently flows at a continuous average rate of 5 gallons/minute or 7,200 gallons/day through drains in the bluffs to the beach.

It is imperative to reduce this water intrusion that includes not just irrigation but also water leaks from the old plumbing and irrigation systems of hundreds of residences and businesses in Del Mar, Del Mar Heights, and Del Mar Terrace. Five gallons/minute translates to only 0.0044 inches/day or 1.6 inches/year over the vast inland area.

The city of Del Mar hired a professional leak detector to check for leaks in city water and sewer mains. It would be helpful for the city to follow up with the city of San Diego to ensure that their systems are not leaking. In addition, Del Mar can coordinate with San Diego to encourage residents and businesses to check annually for water leaks.

It is a very simple process: turn off all faucets and water-using appliances, including automatic ice maker and 3 June 6, 2022 Item 13
4 evaporative cooler. Check the water meter and write down the current reading to tenths of a cubic foot or mark the meter with a felt pen at the needle. Check back at least 15 minutes later to see if the meter reading changed, the needle moved,,or the white triangle in the middle of the dial is spinning which all indicate a water leak. Leak detection professionals can best identify the water leak source that needs to be fixed.

SANDAG’s proposed mitigation for the project includes walkways from the street ends over the deep culverts and new drain channels to an upper bluff trail. They propose extending the existing southern upper bluff trail all the way to Seagrove Park. However, it would necessitate widening the narrower sections to 5 ft and/or creating new trails by digging into the bluff and installing retaining walls and a 3 ft high, wood and cable fall protection fence. That is not advisable as it would create more sources of water intrusion into the unstable bluff.

SANDAG’s increased public access mitigation also includes making an at-grade rail crossing at 7th or 11th Streets.

Nothing is set until they get more public input at a workshop they are planning at city hall in September. Even more significantly, NCTD has to approve as property owner. What are NCTD’s conditions for approval? The question remains, what happens at the end of the 30-year design life of SANDAG’s project when the train is removed from the bluff? How are the trails along the bluff top and down to the beach going to be maintained when the seawalls are removed after the tracks are moved and the soldier piles start failing? Del Mar cannot afford the long-term costs and liability for 1.6 miles of unstable bluffs, especially if NCTD requires indemnification and ownership reverts to Del Mar with the track realignment. That is why SANDAG’s mitigation for this project and proposed tunnel should include a large endowment fund similar to the $40M Southern California Edison used to fund an endowment for San Dieguito Lagoon restoration as mitigation for San Onofre.

Thanks for your consideration,
Laura
P.S. See the estimated long-term bluff retreat of one bluff section from Del Mar’s Sea Level Rise report in 2018:
4 June 6, 2022 Item 13
5 5 June 6, 2022 Item 13
6 6 June 6, 2022 Item 13
1 Melinda Gould
From: K Lare <[email protected]>
Sent: Monday, June 6, 2022 3:36 PM
To: Terry Gaasterland; Dwight Worden; David Druker; Dan Quirk; Tracy Martinez; Ashley Jones; City Clerk Mail Box
Cc: Eddie Lare
Subject: Red dot for City Council Meeting on June 6, 2022 Attachments: presentation to coastal commission 6-8-22.pptx Follow Up Flag: Follow up
Flag Status: Flagged
CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you recognize the sender and know the content is safe.

Please see attached red-dot communication for item # 13 SANDAG Presentation. This is a copy of the slide show I plan to use at the Coastal Commission Meeting Wednesday - while you all do not have the ability to deny a SANDAG project you do have the right to request changes and ask questions. So you do play an important role in all of this. This project is far to large to be approved to go forward. Please ask SANDAG to bring forward smaller more manageable projects.

Please let me know if you have any questions.

Karen
1 June 6, 2022 Item 13
Coastal Commission Meeting
SANDAG Project Request
Karen Lare
6-8-2022
2 June 6, 2022 Item 13
Thank you for all you have done
for the Coastal Communities
It is appreciated!
3 June 6, 2022 Item 13
Something has changed
• We have had pylons and a few seawalls in place for 20 years – they are doing their job
• We have had some failures in the past 50 years that have all been addressed as needed - some by proactive work and some with reactionary work
• This approach has allowed the bluffs and beaches to remain partially in a natural state
• Why has this approach suddenly changed?
3 4 June 6, 2022 Item 13
Suddenly we are faced with “the ultimate”
bluff stabilization proposal
Bluff Stabilization #5 plans to armor the bluffs once and for all • Install 2200 linear ft of new sea walls stretching most of the length of the south bluff tripling the amount of sea walls in Del Mar • Install additional larger longer pylons in areas not yet supported or in need of additional support
• Improve drainage on east side of bluff and out flows
• Install nail walls in Sea Grove Park area to armor the top outer areas of the upper bluff
• This proposed solution is designed to be extremely long term – why? 4 5 June 6, 2022 Item 13
New strategy seems to be
• Fortify the bluffs for the next 50-100 years
• At what costs?
• From 1,000 linear feet of sea walls to 3,200 feet of sea walls + drainage + pylons + nail walls
• Is it all really necessary now? All of it?
5 6 June 6, 2022 Item 13
Sea walls will forever change our beaches
• Damage from the installation of seawalls is well documented • Surfrider Foundation has a lot of scientific research that documents the damages that will result from their installation
• Sea walls will devastate our beaches and all that rely on them to survive • Fishing boats often come all the way to Del Mar from San Diego Bay, why? Because we have a healthy beach ecosystem that feeds the fish on the reef and in the deeper waters
• We can bring in sand on an annual or bi-annual basis but it will not have the same impact on our local ecosystem which needs the consistent access to food
6 7 June 6, 2022 Item 13
The Circle of Life on our Coast
We need
all of it
to make
it work!
You
cannot
pick and
choose
7 8 June 6, 2022 Item 13
It looks harmless on
a map but in reality it
is a very long stretch
of bluff/beach have
you walked it
recently?
8 9 June 6, 2022 Item 13
Taking it all out in 30 years is not the solution
• In 30 years time I can guarantee you that an extension will be asked for
• The beaches will have less sand, be narrower and have less sea life • Offshore waters that once were healthy and thrived will be barren • Bird species that depend on the small sea creatures to live will go elsewhere and it will impact our lagoons
9 10 June 6, 2022 Item 13
My ask of you
• Stand down on approving the “big ask” and direct SANDAG to only bring smaller targeted projects
• Improved drainage has helped and will continue to if coupled with neighbor outreach – runoff is a key problem that can be solved engage the community
• Take this in steps not all at once
• Save some of the bluffs and beaches for that future day when the trains are off the bluffs – allow the next generation to see them before they are all gone
10 11 June 6, 2022 Item 13
Thank you for your time
and the work you do
11 12 June 6, 2022 Item 13
1 Sarah Krietor
From: Bill Carpenter <[email protected]>
Sent: Friday, June 3, 2022 8:00 AM
To: 'Dan Quirk'; Dan Quirk; Terry Gaasterland; David Druker Cc: 'Mark Maggenti'; City Clerk Mail Box; Clement Brown Subject: City Council 6/6 agenda item 14 - proposed Crown Castle license agreement Follow Up Flag: Follow up
Flag Status: Flagged
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Dan, Terry, and Dave -
The best way to get out of a hole is first to stop digging. But in this case, the best way to achieve undergrounding of utilities is to stop stringing fiber optic cable on poles to feed 5G cell sites. Although this proposal is a 10-year master license agreement to allow Crown Castle to string fiber for cell sites only on City poles, it gets us one step closer to having 5G antennas all over the place. Please make a motion to put this on hold pending a review by the undergrounding team.

Del Mar does have a cell site policy that limits the proliferation of cell sites to some degree, but we could get lots of pressure from AT&T to catch up with Verizon cable by putting up hundreds of ugly 5G cell sites all over Del Mar, making utility undergrounding that much more complex and hurting property values. 5G cell sites are NOT what Del Mar residents need to supply gigabit low-latency Internet of the future. We need to catch up with Solana Beach and Encinitas that already have less expensive, more reliable, and higher performance Internet to their homes! What we really need is microtrenching of optical fiber under our streets.

It costs the City nothing to invite Netly (or similar) in to supply and install optical fiber in our streets, which then enables Ting (or other service provider) to sell high bandwidth Internet at lower prices than our residents are currently paying to Verizon or AT&T for medium bandwidth. Please talk with Clem Brown about this. And pause on the Crown Castle license agreement until we have a good plan for Internet of the future.

Thanks!
Bill Carpenter
1149 Luneta Dr
Bill Carpenter | Strategic Advisor & Licensed Broker DRE#01943283 [email protected] | 858.232.2339 m https://linkedin.com/in/CarpenterBill June 6, 2022 Item 14

CITY COUNCIL AGENDA QUESTIONS
JUNE 6, 2022
Item 11. Introduction of an Ordinance to Amend Del Mar Municipal Code Chapter

30.84 Signs Related to Temporary Signs

1. I can't find the provisions in the code that limit temporary signs to 60 days--can you point it out? It needs to be very clear that under the proposed amendments folks can put these signs up in the ROW under some circumstance, but that they have to take them down! The primer says 60 days, and I suspect that this limit is somewhere in the code, but I couldn't find it.

Answer: Del Mar Municipal Code Section 30.84.020.A.7 defines a temporary sign as:
“Temporary Signs are signs used, installed or displayed so as to be visible from an adjacent property or a City right-of-way, continuously or intermittently, for a total duration of not more than 60 days in a calendar year.”
Item 12. Approval of a Conditional Use Permit and Adoption of a Mitigated Negative Declaration (MND) to Authorize Riverpath Del Mar Trail Extension (Phase III)

1. The construction schedule is 4 months from Sept 2023 to January 2024. But, there are lots of off limit periods and possible exceptions. There is a limitation during the rainy season identified as Nov 15-March 31. These time periods overlap--is there work other than grading that continues during the rainy season? Answer: All of the construction work will continue during rainy season. The contractor will be required to implement Best Management Practices (BMPs) to ensure that no runoff occurs from the work site during construction in compliance with the City’s Regional Water Quality Control Board MS4 permit.

2. Is the breeding season prohibition also limited to grading activities, or is it a full halt? BIO 4 seems to say some clearing and grubbing can occur during the breeding "off "season. BIO 4 also seems to say even grading can be allowed during the breeding season (page 19). BIO 5 contemplates some activities, based on surveys, during the "off" season. BIO 6 calls for avoiding clearing and grubbing during the nesting season but only as "feasible." Are we counting on work in these "off" periods to meet our schedule? It reads to me as though there really is no fixed off season. This even seems true as to LCP Condition 1 that has exceptions that can be granted by the Planning Director. I'm hoping for a clearer picture of what we can expect in the field during these various time restricted periods.

Answer: We are not necessarily counting on these off-season activities to meet our construction schedule. The construction schedule was determined with the assumption that no work could be done during this timeframe (Feb-August), but the mitigation June 6, 2022 Item 11, 12 & 14

CITY COUNCIL AGENDA QUESTIONS
JUNE 6, 2022
measures allow the City to begin certain aspects of construction if it is determined by a qualified biologist that no nesting or breeding is occurring by the project site.

3. Finding 4 in the Resolution for the CUP says in part: "... and there are no walls, fences, parking, or loading proposed as part of this Project." Doesn't the project design include safety fencing (post and cable) on portions of the boardwalk? Bio condition 1 also proposes temporary fencing--I think the finding should be clearer that some fencing is contemplated.

Answer: Temporary fencing will be installed during construction, but fencing is not currently part of the anticipated project design scope. There will be railings installed on either side of the boardwalk to ensure pedestrian and lagoon habitat safety, but railings didn’t appear to meet the intent or definition of “fencing” in this case.

4. I'm a bit concerned about the commitments in BIO-3 at page 18 "Offsite mitigation shall be implemented within the subject target site/property located approximately 225 feet northwest of the project (Figure 9, Proposed Mitigation). A portion of the off-site target mitigation property shall be assigned to mitigate for the project (approximately 0.05 acre), and the remaining portion of the property shall be available for other mitigation efforts/projects." My concern is that the City doesn't own this property--do we have a written agreement with the SDRVC allowing the city to make this commitment?
Answer: The acquisition of these parcels by the Conservancy was in coordination with the City in order to specifically mitigate for this project, as the MND did not originally include on-site mitigation for the known permanent impacts. Once the Conservancy entered into negotiations to acquire the properties, the MND was delayed so that on-site mitigation could be incorporated into the environmental document. Trish Boaz represented the Conservancy at November 15, 2021 City Council meeting to provide this update to the Council. While the City does not yet have a written, signed agreement with the Conservancy for use of this site, there is a mutual understanding that an agreement will be put into place for this mitigation. Since additional terms could be required by the permitting agencies, it is not suggested to formalize the agreement until permitting is further along.

5. A bit later BIO 3 says: A protective instrument, such as a conservation easement or restrictive covenant, shall be recorded over the mitigation areas where such a protective instrument does not already exist, unless otherwise not required. This just adds to my confusion. Is there a recorded document? If not, what type and when will there be a "protective instrument" and what will it be? Who decides and on what basis that this commitment may "otherwise not [be] required"? The commitment being made if council approves the permits and HHMP include use of June 6, 2022 Item 11, 12 & 14

CITY COUNCIL AGENDA QUESTIONS
JUNE 6, 2022
somebody else's property, long-term monitoring and maintenance, and an endowment. Do we have a documented right to do all this on SDRVC property? I'm looking for a clear statement that Del Mar has locked down the right to mitigate on this property including all the commitments in these permit approvals and the HHMP.

Answer: See answer to question #4 above.

Item 14. Master License Agreement with Crown Castle Fiber LLC for Wireless Facilities on City Poles in the Public Right-of-Way

1. The license calls for 6 months’ notice to Crown Castle if the city requires relocation for undergrounding. Can we comply with that for Tewa, and 1A, and X-1A? Answer: The proposed Master License Agreement (MLA) only applies to City-owned poles (e.g., traffic signals and streetlights) in the public right-of-way. The City does not own any utility poles that are part of the Undergrounding Project. If the City were to remove and/or underground a City-owned pole with a Crown Castle wireless facility, Crown Castle would be required to rearrange or relocate their equipment at their sole expense, as stipulated in Section 2.5.1 of the MLA.

2. Please correct me if I am wrong, but this license does NOT include 5G facilities? Answer: See answer to question #4 below.

3. Will Crown Castle be installing 5G?
Answer: Crown Castle does not have plans to install any new small cell wireless facilities at this time. The six (6) existing Crown Castle facilities in Del Mar support either 3G or 4G wireless telecommunications.

4. Will the agreement allow 5G?
Answer: The six (6) existing Crown Castle facilities in Del Mar support either 3G or 4G wireless telecommunications. The proposed Master License Agreement (MLA) would allow for the future deployment of wireless facilities that support 5G as allowed under Federal and State law. The MLA is technology agnostic, meaning the agreement specifies terms for small cell wireless sites that are currently in operation within the City, and sets up the application, siting, design, construction, and payment terms for new sites, whether those sites support 3G, 4G, or 5G wireless communications. All future sites within the June 6, 2022 Item 11, 12 & 14

CITY COUNCIL AGENDA QUESTIONS
JUNE 6, 2022
City’s right-of-way will have to comply with all of the conditions and terms in the agreement regardless of type of technology deployed.

5. What is the benefit to Del Mar residents for Crown Castle to install equipment on city poles?
Answer: Crown Castle is a neutral-host telecommunications infrastructure provider, which means they own, manage, and maintain infrastructure on behalf of wireless service providers (e.g., Verizon, T-Mobile, AT&T). The City of Del Mar has had a license agreement with Crown Castle for small cell wireless facilities since 2006 in order to provide better wireless telecommunication coverage and capacity for residents and businesses. Small cell wireless facilities augment wireless network service, especially in areas where terrain prevents traditional towers from providing coverage. In addition, areas where many people congregate need additional capacity to meet the demands placed on networks, and small cell facilities are used to meet those demands.

Additionally, installing equipment on existing City poles reduces or eliminates the need to add/install new poles in the public right-of-way.

6. What is the benefit to Crown Castle?
Answer: The benefit to both the City and Crown Castle for entering into a Master License Agreement is that the conditions and terms for using the City’s poles for both existing and future small cell sites have been pre-established and agreed to by both parties in advance. This saves both parties time and resources during permitting, construction and operation. The MLA also establishes Crown Castle’s usage and maintenance responsibilities. Crown Castle has MLAs with most cities in the County.

7. What services does Crown Castle provide to City residents? Answer: Although Crown Castle is not a wireless service provider, nor an Internet Service Provider (ISP), the wireless service providers (e.g., Verizon, T-Mobile, AT&T) partner with Crown Castle to expand coverage and capacity in areas to meet end-user needs. Crown Castle has a 24/7 Network Operations Center to monitor and restore outages to their network in order to keep people connected to vital services.

June 6, 2022 Item 11, 12 & 14