City of Rancho Palos Verdes Releases Draft EIR for Proposed Portuguese Bend Landslide Remediation Project

Rancho Palos Verdes — The City of Rancho Palos Verdes Feb. 9 released a Draft Environmental Impact Report or EIR for the proposed Portuguese Bend landslide remediation project, an estimated $33 million public works project that aims to slow a continuously moving landslide that has significantly damaged homes, utilities and infrastructure for nearly seven decades.

The Draft EIR, found that the project would have no significant impacts with measures that mitigate potential impacts to a less than significant level. The Draft EIR is available on the city website at www.rpvca.gov/landslide for public review and comment for a 64-day period from Feb. 9 – April 14, 2023.

About the Project

The 240-acre Portuguese Bend landslide is part of a larger complex of ancient landslides located on the south side of the Palos Verdes Peninsula in Rancho Palos Verdes. It was reactivated in 1956 by Los Angeles County’s extension of Crenshaw Boulevard and has been moving ever since, becoming one of the largest continuously active landslides in the U.S. and moving homes by hundreds of feet over the years. The land moves because of the dynamics of surface water percolating into the ground and water trapped deep underground, sliding as much as 8.5 feet per year. The city spends approximately $1 million annually resurfacing a portion of Palos Verdes Drive South that is continuously shifting and cracking due to the landslide. In 2017, the city restarted efforts to explore options for long-term stabilization, forming a city council subcommittee to begin a collaborative effort with the community, holding public workshops and hiring a consultant to conduct a feasibility study. The city council approved a project concept based on the feasibility study in 2019.

The science of landslides is well understood by geotechnical engineers — water facilitates landslide movement. The Portuguese Bend landslide remediation project would remove water trapped deep underground and prevent rainwater from entering the ground in the future. This would be achieved through a combination of the following project components:

• Infilling fissures in the earth to prevent rainwater from entering the ground and contributing to movement
• Creating a surface drainage system using materials reflective of the surrounding environment and planted with native vegetation to convey rainwater to the ocean and prevent it from percolating underground
• Installing hydraugers (horizontal dewatering wells) to extract water trapped deep underground

Similar measures have been successfully implemented at the adjacent Abalone Cove Landslide, which has comparable geologic conditions.

The project has been modeled to reduce land movement to 1-2 inches per year and drastically reduce the threat of sudden movement that could result in the failure of Palos Verdes Drive South, a major road connecting the Peninsula and the City of Los Angeles. If the street were to be severed by sudden major movement — as happened in the neighboring community of San Pedro in 2011 during the Paseo Del Mar Landslide — it would bifurcate the city, creating an over 15-mile detour and eliminating a major connector and evacuation route for the high fire risk peninsula. Roadway failure could also send raw sewage spilling onto the ecologically sensitive shoreline and ocean from above-ground sanitary sewer trunk lines that serve thousands of homes.

About the Draft EIR

Prepared by environmental consulting firm LSA Associates, the Draft EIR is part of a state-required review process that studies how proposed major construction projects could affect the environment and what can be done to mitigate those effects. EIRs are meant to inform decision-makers and the public of any impacts before a project can be built. The Draft EIR for the Portuguese Bend Landslide remediation project studied potential impacts across the following categories: aesthetics, air quality, biological resources, cultural resources, energy, geology and soils, greenhouse gas emissions, hazards and hazardous materials, hydrology and water quality, land use and planning, noise, recreation, transportation, tribal cultural resources, utilities and service systems, and wildfire.

The Draft EIR found that the project would have no significant impacts in any of these areas, but that it could have less than significant impacts associated with construction, including temporary loss of habitat for sensitive species. These impacts would be mitigated through avoidance and minimization methods, habitat restoration, and close biological monitoring, with approval from state and federal wildlife agencies. The habitat loss resulting from the project was anticipated and accounted for in the city’s Natural Communities Conservation Plan/Habitat Conservation Plan (NCCP/HCP), which allows the loss of habitat for certain city projects, provided that avoidance and minimization measures for sensitive habitats and species are implemented. The habitat loss accounted for in the NCCP/HCP is offset by the creation of the city’s 1,500-acre Palos Verdes Nature Preserve. The Preserve and the perpetual preservation and restoration of protected habitat essentially serve as the mitigation for permanent impacts associated with these city projects, including the landslide project.

Next Steps

In addition to the city website, the Draft EIR is available for the review period during regular hours at Rancho Palos Verdes City Hall, the Miraleste Library in Rancho Palos Verdes and the Peninsula Center Library in Rolling Hills Estates. Comments may be submitted in writing to the Public Works Department at Rancho Palos Verdes City Hall (30940 Hawthorne Blvd., Rancho Palos Verdes, CA 90275) or via email to publicworks@rpvca.gov by 4:30 p.m. on April 14, 2023. 

A public hearing to present the Draft EIR findings and solicit feedback is scheduled to take place during the city council meeting on March 21. After the public review period ends, the consultant will review the comments, respond to them and make final revisions to the report. A Final EIR will go before the city council for certification at a future meeting, likely in summer 2023. Certifying the EIR does not mean the city would or would not proceed with project construction.

Construction would depend on multiple factors, including funding availability for the estimated $33 million project. The city has applied for $23.3 million from the Federal Emergency Management Agency’s Building Resiliency Infrastructure and Communities grant funding program (which would require a $10 million non-federal match). Additionally, the city recently received a $2 million allocation in the federal appropriations bill for landslide remediation efforts thanks to a Congressionally directed spending sequest made by Sen. Dianne Feinstein.

Details: www.rpvca.gov/landslide  Questions may be directed to the Public Works Department at publicworks@rpvca.gov.