DR-4344-CA Public Notice 011

FINAL PUBLIC NOTICE: Redwood Valley Water Infrastructure Retrofit, Mendocino County, California │ HMGP-4344-361-007

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 County of Mendocino in Mendocino County, California, to mitigate impacts to existing water infrastructure within the Redwood Valley County Water District (District) from seismic hazards. 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 purpose of the proposed action is to reduce vulnerability of the Redwood Valley water system to seismic hazards and to provide a reliable, code-compliant system to facilitate rebuilding following the Redwood Complex Fire of 2017. The proposed project would upgrade existing water main and service lateral infrastructure within the District to current seismic design standards for water infrastructure. The proposed action consists of abandoning in place approximately 9,100 linear feet of existing 4-inch diameter water mains, installing approximately 10,900 feet of new 6-inch polyvinyl chloride (PVC) water mains, and replacing ¾-inch existing water laterals with 2016 California Residential Code compliant 1-inch diameter laterals designed to meet current seismic standards. The work would include water main upgrades and/or extensions, creating water main loops, where feasible, to increase system resiliency. The project would also include replacement of 150 water meters capable of serving residential fire sprinkler systems, as well as 28 new flush-out valves to improve distribution system water quality and facilitate future installation of fire hydrants.

Portions of the project area are in the 100-year floodplain as depicted on the FEMA Flood Insurance Rate Map (FIRM) Number 06045C1325F, effective date June 2, 2011. The FIRM shows that portions of the project area are within Zone A, designated as a 1 percent annual chance flood hazard, and Zone D, designated as an area of undetermined flood hazard. Installation of new 6-inch water mains and meter replacements would occur in Zone D. Replacement of meters would occur within Zone A.

Two alternatives to the proposed action were considered: Alternative 1, No Action; and Alternative 2: Second Action Alternative. Alternative 1 would involve leaving existing infrastructure in place with no modifications or improvements. This Alternative is not recommended because the community and their water system will remain likely to have a significant and lengthy disruption in water service following a seismic event. Alternative 2 included removing and replacing existing water mains with new ductile iron water mains which conform with modern seismic design and installation standards. This Alternative is not recommended due to the total costs of implementation, with ductile iron estimated at a 218% increase in costs over PVC.

FEMA has determined that the proposed project is the only practicable alternative available; therefore, the proposed action must be located in the floodplain. The proposed action would have no significant adverse impact on the floodplain and would benefit the area by reducing the risk of flooding and flood damage. Therefore, measures to minimize impacts on the floodplain are not necessary. Mendocino County has declared that the proposed action conforms to local floodplain standards, and is responsible for the management, construction, and maintenance of the proposed action.

Additional information about FEMA’s proposed action, including a map of the project area and its location within the floodplain, is available for public inspection and 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, or calling (510) 627-7027. All requests should be received no later than 15 days after publication of this notice. No action will be taken before this date.