DR-4569-CA Public Notice 004

INITIAL PUBLIC NOTICE: Redwood Shores Sea Level Rise Protection, Advance Assistance, San Mateo County, California | HMGP 4569-230-007R

The U.S. Department of Homeland Security’s Federal Emergency Management Agency (FEMA) intends to provide federal financial assistance under the Hazard Mitigation Grant Program to the City of Redwood City in San Mateo County, California, to provide key planning steps in preparation of raising or adding to an existing levee system on the Redwood Peninsula. The proposed action would mitigate impacts from flooding and future sea level rise by developing a preferred alternative that would protect Redwood Shores from extreme storms, a FEMA 100- year tide, and approximately six feet of future sea level rise. Pursuant to Executive Order 11988 (Floodplain Management) and Executive Order 11990 (Wetlands 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 intent to carry out an action affecting a floodplain and wetlands.

The purpose of the proposed action is to protect Redwood Shores from flooding and sea level rise. The proposed action would complete planning activities in preparation for raising or adding to an existing levee system on the Redwood Peninsula. The project would include completing an alternatives analysis, a 60 percent design, and data collection. Data collection would include a coastal hazard analysis, hydrologic and hydraulic studies, land survey and utility location, topographic survey, geotechnical investigation, and site reconnaissance. Geotechnical investigations would include soil borings and/or Cone Penetration Tests (CPTs), laboratory testing, and analysis along the preferred levee realignment determined by the alternatives analysis. Approximately five borings would be drilled into the proposed levee alignment generally be to a depth equivalent to two to three times the planned levee or floodwall height. The diameter of soil borings is estimated to range from 2.5 inches to 6 inches, depending on the type of sampler used. Project locations for geotechnical testing, staging areas, and access routes would be located on previously disturbed or graded areas.

The project area is in the 100-year floodplain as depicted on the FEMA Flood Insurance Rate Map (FIRM) Numbers 06081C0169G, 06081C0167G, 06081C0186F, 06081C0188F, all effective April 5th, 2019. The FIRMs show that the majority of the project area lies within Zone X, an Area with Reduced Flood Risk due to a Levee. Other portions of the project area are in Zone X, Areas with 0.2% Annual Chance Flood Hazard or Areas of 1% Annual Chance Flood Hazard with an average depth of less than one foot or with drainage areas of less than one square mile. The outermost parts of the land (those adjacent to the Steinberger Slough and the Redwood Shores Lagoon) within the project area are in Zone AE, areas that have a 1-percent probability of flooding every year and have Base Flood Elevations (BFEs) of ten or eleven feet.

The U.S. Fish and Wildlife Service National Wetlands Inventory map shows estuarine and marine wetlands and freshwater emergent wetlands within the project area.

Additional information about FEMA’s proposed action, including maps showing the potential impacts on floodplains and wetlands, may be obtained 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 within 15 days after publication of this notice.