PA-07-IA-4421-PW-01587 GM 104602 Sioux City Sewer Pipe

FINAL PUBLIC NOTICE

Sioux City (Woodbury County) has applied for Federal Emergency Management Agency (FEMA) Public Assistance (PA) Program funding through Iowa's Homeland Security and Emergency Management Division (IHSEMD).

Under the National Environmental Policy Act (NEPA), federal actions must be reviewed and evaluated for feasible alternatives and for social, economic, historic, environmental, legal, and safety considerations. Under Executive Order (EO) 11988 and EO 11990, FEMA is required to consider alternatives, and to provide a public notice of any proposed actions in or affecting floodplains or wetlands. This notice may also fulfill requirements under Section 106 of the National Historic Preservation Act (NHPA).

Funding for the proposed project will be conditional upon compliance with all applicable federal, tribal, state, and local laws, regulations, floodplain standards, permit requirements and conditions.

Sub-Applicant: Sioux City, City of

Project Title: 104602-Sioux City Sewer Pipe, PA-07-IA-4421-PW-01587

Location of Proposed Work: The legal location of the Improved Project will be Section 34, Township 89N, Range 47W with an approximate start latitude/longitude of 42.49021, -96.38134 and an approximate end latitude/longitude of 42.47699, -96.38430.

Special Flood Hazard Area Zone:

This project will perform work in the A Zone, otherwise known as the area of 1% annual chance of flooding, per Woodbury County FIRM Panel 19193C0182F, effective on 07/17/2024.

Proposed Work and Purpose:

Utilizing FEMA's Improved Project process, Sioux City proposes to rehabilitate the entire sanitary interceptor sewer system located under the concrete lined channel using trenchless methods, which include heavy cleaning, debris removal, and structural lining of the existing pipes and manholes.

The new proposed scope of work includes the following:

• Construction of entrance and exit ramps into the channel to allow the necessary equipment to access the interceptor main, manholes, and off-interceptor sewer pipe sand structures.

• Filling of existing voids under the channel bottom along the work path as necessary, to provide a safe driving and working area.

• Heavy cleaning, debris removal, and disposal within the 48 IN interceptor main and manholes along the entire length of the channel, approximately 5,200 LF of 48 IN RCP and 294 VF of 60 IN diameter reinforced concrete manhole.

• Removal of upper portion of the concrete channel around the manhole and excavation of soils.

• Removal of unnecessary manholes (not required by current codes and standards) through excavation and insertion of new concrete pipe as a replacement where the previous manholes existed.

• Installation of a structural liner technology within the pipe. These technologies are a continuous liner from manhole to manhole.

• Installation of new manhole sections and lids to replace those removed for the installation of the liner technology.

• Repair of the remaining manhole sections through removal of the existing liner and any necessary repairs to the wall and floor sections.

• Installation of the liner technology or spray-on system for the protection of the existing and new manholes sections.

• Backfill and restoration around manholes including concrete replacement for the channel.

• In addition to the scope of work summarized above for the interceptor sewer system, Sioux City also intends to repair or replace off-interceptor sanitary sewer infrastructure under and immediately adjacent to the channel.

Project Alternatives:

Alternative #1 (No Action): During the project scoping phase, Sioux City contracted an engineering firm to evaluate the existing conditions. Using multi-sensor inspection technology, multi-channel ground penetrating radar, and visual inspection, the interceptor sewer and channel infrastructure were found to be in poor condition. The no-action alternative would not be appropriate because the restoration of the sewer pipes is considered a critical action. The pipes are an integral part of the city's wastewater management plan and need to function properly.

Alternative #2 (Alternative Alignment): A new pipe alignment outside the channel, and therefore outside of the floodplain, was evaluated but deemed infeasible. The benefit from this option is that it is much less likely to be adversely impacted by the floodplain. However, there would be significant environmental impacts since a new pipe would need to be connected to the existing public sewer collector mains and private sewer laterals. This would significantly increase the project cost and extend the timeline far past what is reasonable.

Alternative #3 (To restore back to Pre-disaster): Sioux City originally proposed to repair the concrete sewer pipes and manholes back to pre-disaster condition. However, the previously approved construction plans were determined to be infeasible due to unstable soil conditions and structural concerns. Since the entirety of the concrete channel, including the formerly identified damaged section in addition to the upper section, had been flooded and was the same age, the likelihood for damage required additional evaluation. Portions of the upper section of pipe, manholes, and existing liner material were damaged and had already allowed for debris to wash into the pipe. Therefore, the entirety of the 48 IN interceptor sewer was recommended for rehabilitation.

Comment Period:

Comments are solicited from the public, local, state, or federal agencies, and other interested parties in order to consider and evaluate the impacts of the proposed project on the community. Interested parties may submit comments, questions, or request a map of this specific project by writing to: Acting Regional Environmental Officer Edward Hubert, Environmental and Historic Preservation Branch, Federal Emergency Management Agency, Region 7, 11224 Holmes Road, Kansas City, MO, 64131, or by email to Acting Regional Environmental Officer Edward Hubert at fema-r7-ehp-publiccomment@fema.dhs.gov. Please send comments with the subject line: PA-07-IA-4421-PW-01587 11988 Sioux City Sewer Pipe COMMENT.

All comments are due by no later than 15 days of the posted date of this notice.

POSTED ON: 7/12/2025 and 7/19/2025