Del Mar Bluffs Emergency Repair at MP 245.4
Summary
SCH Number
2021100185
Public Agency
San Diego Association of Governments
Document Title
Del Mar Bluffs Emergency Repair at MP 245.4
Document Type
NOE - Notice of Exemption
Received
Posted
10/12/2021
Document Description
The purpose of the proposed project is to secure the track bed in its existing alignment. A slide occurred approximately 0.2 mile north of the proposed project area on February 28, 2021 after an existing seawall collapsed. The seawall collapsed because of ongoing wave erosion the undercut the foundation of the seawall, causing the artificial fill the wall was securing to fall onto the beach below.
The proposed project area is very similar to the area that collapsed in February 2021. The proposed project area consists of an existing concrete seawall that was built over 100 years ago that secures approximately 20,000 CY of artificial fill. After the seawall at MP 245.2 collapsed, project engineers studied the seawall in the proposed project and determined that there is an imminent risk of failure until it can be stabilized. If left in its existing condition, there will be a significant risk to public safety due to the active and episodic nature of the bluffs. Amtrak’s Pacific Surfliner intercity passenger rail service through the proposed project area is the nation’s second busiest, serving six counties and 351 miles of the southern California coastline. In addition to Amtrak, this rail corridor is shared with COASTER commuter rail services and Burlington Northern Santa Fe (BNSF) Railway and Pacific Sun freight services.
A Right of Entry permit from the State of California is required for access to the proposed project area. The proposed project consists of installing 47 Cast-in-Drilled-Hole concrete piles in a row directly west of the existing seawall at MP 245.4 with a 2-foot wide slurry trench in between the existing wall and the piles. The 32-foot deep piles will be drilled into the ground and will be capped by a concrete grade beam. This concrete grade beam and a small portion of the piles may become visible if the beach sand is washed away in winter storms. The concrete will be colored to match the existing surroundings. This pile cut off wall will reinforce the existing seawall and protect the bottom of it from being undercut by wave-based erosion, which is what caused the seawall at MP 245.2 to collapse. Access through an existing State Parks parking lot, through an existing beach access road, and through State Park land is required to reach the proposed project area, which is located on land owned by the North County Transit District.
Contact Information
Name
Keith Greer
Agency Name
San Diego Association of Governments
Contact Types
Lead/Public Agency / Project Applicant / Parties Undertaking Project
Phone
Email
Location
Cities
Del Mar
Counties
San Diego
Regions
Countywide
Other Information
Del Mar Bluffs area south of 4th Street in the City of Del Mar on Torrey Pines State Beach, San Diego County.
Notice of Exemption
Exempt Status
Emergency Project
Type, Section or Code
15269(b)(c)
Reasons for Exemption
The proposed project is required to protect the track bed of this section of the LOSSAN Corridor. Wave runup is undercutting the foundations of a 100-year-old seawall. A similar seawall located to the north less than 0.2 miles away failed in February 2021 and a similar failure is imminent at this location. An engineering evaluation (HNTB 2021) concluded that the Anderson Canyon seawall does not meet the minimum factor of safety of 1.5 for overturning (1.02) and sliding (0.98) and needs urgent repairs to avoid failure. The construction of a cut off wall in front of the existing seawall will stabilize the wall from being undermined by waves during high tides and storm surge. Without the proposed project, the existing seawall and bluff are susceptible to failure and constitutes a threat to public health and safety until it is reinforced.
County Clerk
San Diego
Attachments
Notice of Exemption
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