DR-4407-CA Public Notice 016

FINAL PUBLIC NOTICE: Regional Sewer Lift Station Replacement Project, Orange County, California | HMGP 4407-291-118

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 Moulton Niguel Water District (MNWD) in Orange County, California, to provide seismic and flood hazard mitigation (proposed action). 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 final decision and an explanation of the alternatives that were considered.

The purpose of the proposed action is to reduce the risk of raw sewage spills during seismic and flood events. The proposed action consists of replacing two existing force mains with a more durable material, increasing the size of the force mains, relocating the force mains to a new alignment along the east side of Sulphur Creek Reservoir, and repurposing one of the existing force mains to be a gravity-only effluent transmission main for emergency use. The new alignment would begin at MNWD’s Regional Lift Station and terminate at the South Orange County Wastewater Authority’s Joint Regional Treatment Plant directly south of the park. New pipelines would be installed using open trench methods, and trenchless methods would be used at stream crossings. Trenchless installation methods may include microtunneling or jack and bore construction and would be used to avoid impacting streams and wetlands where feasible.

The project area is depicted on the FEMA Flood Insurance Rate Map (FIRM), Map Number 06059C0437J, effective date December 3, 2009. The FIRM shows that the project area partially 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 partially in Zone A, an area that has a 1-percent probability of flooding every year and where predicted floodwater elevations have not been established. A small portion of the project area also lies within a floodway.

The U.S. Fish and Wildlife Service National Wetlands Inventory map shows freshwater forested/shrub wetlands along Sulphur Creek. A biological site survey in 2017 identified a total of approximately 0.94 acres of potential wetlands in the study area. The project would temporarily impact approximately 0.007 acres of potential wetlands. A map of the project area and its location within the floodplain and wetlands 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.

Two alternatives to the proposed action were considered: Alternative 1: no action alternative; and Alternative 2: second action alternative. Alternative 1, no action, would not replace the existing mains. The no action alternative is not recommended because it would not meet the purpose and need of mitigating seismic and flood hazards to the wastewater infrastructure and the risk of failure of the force mains and associated water contamination and health risks from spilled raw sewage would remain high. Alternative 2 included an assessment of ten possible alternatives to the proposed action to mitigate seismic and flood risk to wastewater infrastructure. Based on this assessment, the next most feasible alternative would be 300 feet longer than the proposed action, would require construction across La Paz Road, and would have expensive design, construction, and energy costs. Thus, Alternative 2 is not recommended. FEMA has determined that the proposed action is the only practicable alternative available; therefore, the proposed action must be located in the floodplain and wetlands.

The proposed action would have no significant adverse impact on the floodplain or wetlands and would benefit the area by reducing the risk of damage to wastewater infrastructure during seismic or flood events. The proposed action would also reduce the risk of water quality contamination from raw sewage and therefore protect the natural functions and values of floodplains and wetlands. Therefore, measures to minimize impacts on the floodplain and wetland are not necessary. MNWD is responsible for implementing and monitoring the proposed action and ensuring it conforms to local floodplain standards. MNWD must also coordinate with the U.S. Army Corps of Engineers and the California State Water Resources Control Board and obtain any required permit authorizations and/or approvals.

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.