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FINAL PUBLIC NOTICE: Russian River-Cotati Intertie Pipeline Seismic Hazard Mitigation Project, Sonoma County Water Agency — PDMC PJ 09 CA 2010 013 and PDMC PJ 09 CA 2011 003

Notice Date

The U.S. Department of Homeland Security’s Federal Emergency Management Agency (FEMA) intends to provide federal financial assistance under the Pre-Disaster Mitigation Program to the Sonoma County Water Agency (Subrecipient), through the California Governor’s Office of Emergency Services, for the Russian River-Cotati Intertie Pipeline Seismic Hazard Mitigation Project (proposed action). Pursuant to Executive Order 11988 (Floodplain Management), Executive Order 11990 (Protection of Wetlands), 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 during the determination process.

The proposed action would consist of replacing portions of the underground Russian River-Cotati Intertie Pipeline at two waterbody crossings due to seismic concerns. One crossing is at the Russian River and the other is at Mark West Creek. Work on the Russian River Crossing would consist of abandoning and replacing an underground pipe connection to one of the Mirabel Facility collector wells; abandoning and replacing sections of the existing 48‑inch-diameter steel underground Russian River-Cotati Intertie pipeline on the northern and southern sides of the Russian River; and installing supporting appurtenances, including a concrete meter vault, approximately three cathodic protection stations and/or corrosion test stations, air valves, and appurtenances. Work on the Mark West Creek Crossing would include installation of approximately 767 linear feet of a 48‑inch-diameter steel underground pipeline segment across the Mark West Creek channel and adjacent uplands. The new pipes and appurtenances would be installed using open trenches. All trenches would be backfilled and the existing grade would be restored. Revegetation would occur in riparian areas. After construction is completed, all components of the proposed action would be at or below grade except for a permanent soil disposal site.

The action area is shown on the Sonoma County, California and Incorporated Areas Flood Insurance Rate Maps (FIRMs): Map Number 06097C0545E and Map Number 06097C0685E, effective December 2, 2008. Based on the FIRMs, the proposed location of the permanent soil disposal site would be located outside the floodplain in unshaded Zone X, which is defined as “Areas determined to be outside the 0.2% annual chance floodplain.” All other components of the proposed action would be located in the Special Flood Hazard Area Zone AE, an area with a 1-percent chance of flooding every year, and in a regulatory floodway. All parties interested in receiving a copy of the FIRM maps should contact the FEMA Region IX Environmental Officer at the address or phone number listed at the bottom of this notice.

Wetlands have been identified in the action area adjacent to the Russian River and the crossing at Mark West Creek. Vegetation removal, flow exclusion structures, dewatering, and installing and using flow bypass systems would be necessary during construction adjacent to the Russian River and at Mark West Creek. Vegetation removal in wetlands would be minimized to the extent possible. The proposed action would result in temporary impacts to wetlands, and the site would be restored after construction is complete. Construction and implementation of the proposed action is not anticipated to result in permanent impacts to wetlands.

Because the pipeline is in the floodplain and work would need to occur immediately adjacent to the Russian River, the no action alternative is the only alternative outside of the floodplain and wetlands. Under the no action alternative, the pipelines would continue to be at risk of failure during an earthquake. Therefore, the no action alternative is not recommended. FEMA determined that the proposed action is the only feasible alternative available to the Subrecipient at this time. The proposed action would not adversely affect the floodplain or wetlands as restoration activities approved by the U.S. Army Corps of Engineers, National Marine Fisheries Service, and California Department of Fish and Wildlife would commence once construction concludes, and the restoration activities would follow multi-year survival criteria method for determining successful restoration. The Subrecipient would be responsible for implementing and monitoring the proposed action in accordance with the Sonoma County floodplain regulations.

Additional information about FEMA’s proposed action 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; or by calling (510) 627‑7027. All requests should be received no later than October 15, 2019. No action will be taken before this date.

Last updated Feb 4, 2020

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