DR-4240-CA Public Notice 001

FINAL PUBLIC NOTICE: Esplanade Infrastructure Preservation, Project (Phase 2c), San Mateo County, California | HGMP 4240-053-026

The U.S. Department of Homeland Security’s Federal Emergency Management Agency (FEMA) proposes to provide federal financial assistance under the Hazard Mitigation Grant Program to the City of Pacifica (City) in San Mateo County, California, to implement the Esplanade Infrastructure Preservation Project (Phase 2c) (proposed action). Pursuant to Executive Order 11988 (Floodplain Management) and FEMA’s implementing regulations at Title 44 of the Code of Federal Regulations Part 9, FEMA hereby provides interested parties with a notice of its final decision and an explanation of the alternatives that were considered.

The city proposes to construct a sheet pile and shotcrete wall along the toe of the coastal bluff near 310-330 Esplanade Avenue (start: 37.652361, -122.493343; end: 37.654111, -122.493281) to protect the area from further erosion and scouring. Prior to construction, existing rip rap along the beach and the remnants of a shotcrete and soil nail wall along the bluff would be removed. The area of the proposed sheet pile wall would then be graded, and the sheet pile wall would be installed above the high tide water line under dewatered conditions. A temporary sand dike or embankment would be maintained throughout the project to create a barrier from wave action. The sheet pile wall would extend below summer sand levels and a concrete cap would be installed on top of the sheet pile to serve as a bridge between the shotcrete upper half and sheet pile lower half. Tiebacks would be put in place to support the wall, and back drains would be installed to relieve hydrostatic pressure. Structural facing would be installed along the bluff to provide further armoring against erosion. A finished facing would be installed on the exterior of the structural facing and could be sculpted to mimic the surrounding color and texture of the bluff. Construction would be conducted between early summer to winter. Equipment would include large excavators, likely use of a crane on top of the bluff, heavy‐duty tieback drilling equipment, and heavy‐duty sheet pile driving equipment (vibratory or impact hammer). No vehicles or heavy equipment would be operated in open water habitat. Access to the project area by foot and small machinery can be through the public access trail at 100 Esplanade Avenue. Larger equipment would either be lowered from the bluff top by crane or driven to the project site via an access road at W. Manor Drive and Esplanade Avenue during low tides.

The project site overlaps Zone VE, a Coastal High Hazard Area (CHHA) where wave action and fast-moving water can cause extensive damage during a base flood event (depicted on Flood Insurance Rate Map [FIRM] Number 06081C0038F effective 8/2/2017).

A map of the project area and its location with respect to the CHHA is available for public inspection. Parties interested in receiving a copy of the map should contact the FEMA Region IX Environmental Officer using contact information provided in this notice.

Four alternatives to the proposed action were considered: Alternative 1, No Action; Alternative 2, Grading of Bluffs to a Lesser Gradient; Alternative 3, Sand Replenishment; and Alternative 4, Rock Revetment. Alternative 1 would include taking no action and allowing current conditions to persist. This Alternative is not recommended because it would allow the continued retreat of the coastal bluff towards Esplanade Avenue and would hasten the eventual undermining of the road and surrounding properties from erosion and scouring. Alternative 2 proposed to grade the bluff to a 45-to-50-degree inclination, which would have created a relatively stable slope under static conditions. Given the highly erodible nature of the bluff, however, both the face and toe of the bluff would continue to be impacted by heavy erosion from direct rainfall and wave run-up. Alternative 3, or sand replenishment along the bluff toe, also was explored. This alternative was determined to be unsustainable as sand is rapidly removed from the beach under winter storm conditions, and sand replenishment would not provide lateral support to the bluff. Finally, Alternative 4, or placement of a rock revetment, was explored. Geotechnical borings north of the project site revealed no bedrock to a depth of 40 feet, however and a rock revetment founded on weak terrace materials would be susceptible to erosional damage and require a wide footprint that could impact the aesthetic qualities and functional uses of the shoreline. The California Coastal Commission approved construction of a near vertical seawall on the adjoining property to the north of the project site, and the proposed action has been designed consistent with that approach.

FEMA has determined that the proposed project is the only practicable alternative available; therefore, the proposed action must be in the CHHA. The proposed action would have no significant adverse impact on the CHHA and would benefit the area by reducing the risk of further erosion and scouring of the bluff and shoreline. Measures to minimize impacts on the CHHA are not necessary. The city has confirmed that the proposed action will conform to appropriate Coastal Commission standards, and would be responsible for the management, construction, and maintenance of the proposed action.

Additional information about FEMA’s proposed action may be requested by writing the FEMA Region IX Environmental Officer at FEMA, 1111 Broadway, Suite 1200, Oakland, California 94607, or fema-rix-ehp-documents@fema.dhs.gov. All requests should be received no later than 15 days after publication of this notice. No action will be taken before this date.