FINAL PUBLIC NOTICE

MERCED WASTEWATER TREATMENT FACILITY
AERATION BASIN SEISMIC MITIGATION PROJECT
MERCED COUNTY, CALIFORNIA
HMGP-4683-1047-051

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 City of Merced (Subapplicant or City) in Merced County, California, to minimize seismic hazards by removing and replacing two aeration basins and ancillary infrastructure and completing seismic retrofits to the blower building at the City’s Wastewater Treatment Plant (WWTP) (Proposed Action). Pursuant to Executive Order 11988 (Floodplain Management) and FEMA’s implementing regulations at Title 44 Code of Federal Regulations Part 9, FEMA hereby provides interested parties with a notice of its final decision and an explanation of the alternatives considered.

The purpose of the Proposed Action is to increase the facility’s resiliency to seismic hazards. The Proposed Action consists of the demolition and removal of existing Aeration Basins 1 and 2 and their replacement with conventional activated sludge technology; removal and replacement of ancillary infrastructure for the basins (e.g., basins splitter box, secondary clarifier splitter box, aeration blowers and aeration system, drain pump station); and seismic retrofitting of the Blower Building through increasing strut capacity on the structure’s west side, adding to the sub-diaphragm to comply with length-to-width ratio requirements, and demolishing the existing monorail system.

The project area is depicted on FEMA Flood Insurance Rate Map (FIRM) Panel 06047C0420G, effective date December 2, 2008. The FIRM shows that the Proposed Action lies within Zone X, an Area with Reduced Flood Risk Due to Levee. The accredited levee along the perimeter of the WWTP is verified to provide protection up to the 100-year flood level.

A map of the project area and its location within the floodplain is available for public review. Parties interested in receiving a copy of the map should contact the FEMA Region 9 Environmental Officer using contact information provided in this notice.

Three alternatives to the Proposed Action were considered: the No Action Alternative, Alternative 1: Replacement with Membrane Bioreactors (MBRs), Alternative 2: Flood Mitigation for Areas South of Bear Creek, and Alternative 3: Levee Improvements/Extensions. Under the No Action Alternative, no construction activity would occur to address the WWTP buildings’ seismic vulnerability. This Alternative is not recommended because if no action is taken, the WWTP would remain at risk of failure or damage from a seismic event, which could impact the City’s ability to provide wastewater treatment services to residents. Under Alternative 1, the existing solid separation process at Aeration Basins 1 and 2 would be replaced with MBR technology. Alternative 1 is not recommended due to its associated increased capital and lifecycle costs. Alternative 2 would involve voluntary buyout of flood-prone commercial and/or residential structures. This
Alternative is not recommended because no specific/detailed program has been developed for buyouts, and the structures in the project area are associated with a critical WWTP, which means that associated costs would be higher, and the timeline for implementation would be unknown. Alternative 3 would involve levee improvements or extensions designed to reduce future flooding damage. This alternative is not recommended because design plans have not been developed, resulting in higher associated costs and a longer timeline for development and implementation.

FEMA has determined that the Proposed Action is the only practicable alternative available; therefore, the Proposed Action must occur within the floodplain. The Proposed Action would not have a significant adverse impact on the floodplain—the WWTP would need to remain in full compliance with its existing permitted discharge requirements during the entirety of project implementation, and the project would benefit the area in the long-term by reducing the risk of damage to the WWTP in the event of seismic activity. Therefore, additional measures to minimize impacts on the floodplain are not necessary. The City of Merced has stated that the Proposed Action conforms to local floodplain standards, and would be responsible for the management, construction, and maintenance of the Proposed Action.

Additional information about FEMA’s Proposed Action may be requested by writing to the FEMA Region 9 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.

Final Public Notice (PDF)