DR-4344-CA Public Notice 024

INITIAL PUBLIC NOTICE: Arroyo Las Positas Restoration Project (Phase 1b-Geotech), Alameda County, California | HMGP 4344-138-035

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 Livermore in Alameda County, California, to complete geologic mapping and soil sampling to support the restoration and regrading of Arroyo Las Positas Creek. The overall proposed action would mitigate impacts from floods by removing sediment and invasive vegetation on the creek banks, grading the creek banks, and replanting native riparian vegetation along the regraded portion of the creek. Pursuant to Executive Order 11988 (Floodplain Management), 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 wetland.

The purpose of the proposed action is to reduce flood hazards by removing silt, sediment, and invasive plant species along Arroyo Las Positas Creek; grade the Las Positas Creek banks to increase flood conveyance capacity; fill two damaged ponds and regrade the damaged area; and replant native riparian vegetation along the regraded portion of the Las Positas Creek. Phase 1b of the proposed action consists of geologic mapping and shallow hand-excavated soil sampling in sections of the creek channel above the waterline, where excess sediment has accumulated. Sampling would be limited to eight samples measuring a maximum of 14-inches in diameter by 8-inches deep.

The project area is in the 100-year floodplain as depicted on the FEMA Flood Insurance Rate Map (FIRM) Numbers 06001C0329G, effective date August 3, 2009. The FIRM shows that the project area lies within Zone AE, an area that has a 1-percent probability of flooding every year and where predicted floodwater elevations have been established, and a floodway.

The U.S. Fish and Wildlife Service National Wetlands Inventory Map shows potential freshwater emergent wetland adjacent to the project area. The City of Livermore would have an on-site biologist identify wetlands in the project area and the biologist would ensure the avoidance of soil sampling within wetlands.  

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.