DR-4344-CA Public Notice 020

FINAL PUBLIC NOTICE: South Bay Force Main Replacement and Resiliency Project, Humboldt County, California | HMGP-4344-540-19

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 Humboldt Community Services District in Humboldt County, California, to mitigate risks from flooding and the potential for saltwater intrusion by increasing the resilience of the force main (proposed action). 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 increase the resilience of the force main by reducing risks from flooding and the potential for saltwater intrusion. The proposed action consists of 1) site preparation; 2) open trenching and horizontal directional drilling to replace approximately 2.1 miles of existing asphalt-cement (AC) sanitary sewer force main with high-density polyethylene (HDPE) line; 3) connecting the new sewer force main to the existing system; 4) abandoning the existing sewer force main in place; and 4) restoring disturbed areas.

The project area is depicted on the FEMA Flood Insurance Rate Map (FIRM), Map Numbers 06023C0839G and 06023C1005G, effective 06/21/2017. The proposed action lies within Zone AE, an area that has a one-percent probability of flooding every year.

A map of the project area and its location within the floodplain 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, and Alternative 2, Second Action Alternative. Alternative 1 would leave the existing sewer force main in place and risk damage and increased repair costs from potential sea-level rise and saltwater intrusion. This Alternative is not recommended because large flood events and increasing levels of groundwater intrusion would continue to damage the existing AC force main and would eventually result in its failure. Alternative 2 includes pursuing an adjacent restoration project instead of the proposed project that could provide some protection to the floodplain. This Alternative is not recommended because it would only partially alleviate potential impacts to the existing AC pipeline resulting from sea level rise. Since the pipeline is a critical piece of infrastructure that services 1,237 residential connections and 49 commercial/industrial connections, complete replacement is considered to be the most effective and feasible alternative. 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. The Humboldt Community Services District has declared 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 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.