Final Public Notice - Central Street Crossing of Short Creek (Phase 1)
CENTRAL STREET CROSSING OF SHORT CREEK (PHASE 1)
MOHAVE COUNTY, ARIZONA
HMGP-4524-004-012
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 Mohave County Flood Control District (Subapplicant) in Mohave County, Arizona. The Subapplicant proposes to perform Phase 1 activities (design work, geotechnical survey, and hydrologic and hydraulic [H&H] study) that would support the investigation of solutions to elevate a low-water crossing bridge over Short Creek (Proposed Action). Pursuant to Executive Order 11988 (Floodplain Management), Executive Order 11990 (Wetlands 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 flood conveyance capacity of the existing Central Street Bridge crossing over Short Creek from the 10-year flood event to the 100-year event. The Proposed Action includes pre-construction activities consisting of a geotechnical survey, utility relocation planning, development of construction blueprints, and acquisition of easements and environmental permits. For the geotechnical survey, a mobile drill rig would be used to drill eight boreholes to auger refusal or up to 20 feet below the ground surface. Two boreholes would be drilled on Central Street through the existing pavement (to auger refusal or up to 15 feet below the ground surface), and six boreholes would be drilled adjacent to the existing bridge in the earthen channel (upstream and downstream to auger refusal or up to 20 feet below the ground surface) within the existing right-of-way and the proposed bridge’s construction footprint. The two borings drilled through pavement would be backfilled with a concrete slurry, and the six boreholes drilled in the earthen channel would be backfilled with native material. All boring locations would be accessed using the existing paved roadway network.
The project area is depicted on the FEMA Flood Insurance Rate Map (FIRM), Map Number 04015C0276G, effective date November 18, 2009. The FIRM shows that the Proposed Action lies within Zone AE, an area with a 1 percent probability of flooding every year and where predicted floodwater elevations have been established. The U.S. Fish and Wildlife Service National Wetlands Inventory map shows riverine wetlands within the project area.
A map of the project area and its location within the floodplain and wetland is available for public review. Parties interested in receiving a copy of the map should contact the FEMA Region 9 Environmental Officer using the contact information provided in this notice.
Two alternatives to the Proposed Action were considered: the No Action Alternative and Alternative 1. Under the No Action Alternative, no construction activity would occur to mitigate hazards resulting from insufficiencies of Central Street Bridge’s conveyance capacity. The No Action Alternative is not recommended, as it would allow the risk of bridge damage or failure due to flood hazards to persist. Alternative 1 would upgrade the Hilldale Street crossing of Short Creek instead of the Central Street crossing. Alternative 1 is not recommended due to its increased cost compared to the Proposed Action.
FEMA has determined that the Proposed Action is the only practicable alternative available; therefore, the Proposed Action must occur within the floodplain and wetland. The Proposed Action would not have a significant adverse impact on the floodplain and wetland and would benefit the area by reducing the risk of flooding and flood damage. Therefore, measures to minimize impacts on the floodplain and wetland are not necessary. Colorado City 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.