Public Notice - FEMA Rehabilitation of High Hazard Potential Dams (HHPD) Grant

The Federal Emergency Management Agency (FEMA) has received a subgrant application for NCDEQ in Rutherford County. Pursuant to Executive Order 11988 and 44 CFR Part 9.12, notice is hereby given of FEMA’s intent to provide funding for this project under the Rehabilitation of High Hazard Potential Dams (HHPD) grant.

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. - Executive Order (EO) 11988 and EO 11990 requires FEMA to consider alternatives - and provide a public notice of any proposed actions in or affecting floodplains or wetlands. EO 12898 requires FEMA to provide the opportunity for public participation in the planning process and to consider potential impacts to minority and low-income populations. This notice may also fulfill requirements under Section 106 of the National Historic Preservation Act (NHPA).

President Biden issued new Executive Orders 13985 and 14008 in January 2021 to further address the need to achieve environmental justice and equity across the federal government. The issuance of the new executive orders more than 20 years after Executive Order 12898 was signed indicates the administration’s directive to federal agencies to renew their energy, effort, resources and attention to environmental justice. FEMA is working with recipients/subrecipients to identify communities with Environmental Justice concerns and provide an avenue for local groups and non-profits with an Environmental Justice mission to self-identify so that FEMA Programs can start to work with them on specific projects from the beginning of the application process.

This notice serves as a project‐specific notice for FEMA’s funding action located within a Special Flood Hazard Area. FEMA has determined the only practicable alternative is to fund the proposed geotechnical investigations and surveys. 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. This action complies with the National Flood Insurance Program (NFIP) requirements.

Responsible Entity:    Rehabilitation of High Hazard Potential Dams (HHPD

Applicant: North Carolina Dept of Environmental Quality (NCDEQ)                   

Project Title(s): Lake Lure Geotechnical Investigations 

Location of Proposed Work and Floodplain Insurance Rate Map (FIRM) Panels:

FIRM Panel effective date: . Site is located within a Zone AE mapped floodplain. Site(s) are located within or adjacent to wetlands. [https://www.fws.gov/wetlands/Data/Mapper.html]

Proposed Work and Purpose: The North Carolina State Dam Safety Program is proposing that work will begin with a geotechnical investigation and related field studies within the proposed footprint of the new dam location (35.42593, -82.18355).  Field investigations within the dam footprint will include geologic mapping of the exposed bedrock, geotechnical borings, geophysical investigations on the abutments, and an additional topographic survey on the abutments. The new dam is presumed to consist of roller compacted concrete gravity constructed immediately downstream of the existing dam. Initial access to the area during the investigation portion of the plan will use an existing paved access road on the right abutment downstream of the existing dam. There will need to be new temporary access roads and working platforms to access boring locations.

Project Alternatives:  

Three dam rehabilitation alternatives were evaluated to extend the service life of the dam and address the identified dam safety deficiencies to bring the dam into compliance with NCDEQ Dam Safety requirements. In addition, consideration was also given to a replacement dam immediately downstream of the existing dam. While all of the alternatives address the identified dam safety deficiencies, each alternative has distinct advantages and disadvantages with respect to cost, service life, technical performance, and various other qualitative factors, as discussed herein. Based on our evaluation and consideration for each of these factors, the full dam replacement option, excluding replacement of the hydroelectric facilities, appears to be the most advantageous and lowest risk option and was therefore selected.

The following is a synopsis of the other alternatives that were considered.

(1) No Action Alternative: Lake Lure Dam is nearly 100 years old. It is in fair condition considering its age; however, it

should not be expected to have a significantly longer service life without major improvements. In addition, the dam does not meet NCDEQ Dam Safety requirements for hydraulic capacity and structural stability under seismic loading conditions. The concrete gravity gated spillway sections also do not meet global stability requirements for the load cases analyzed, and there is no functional reservoir drain.

In addition to the preferred alternative for a replacement dam immediately downstream of the existing dam, three dam rehabilitation alternatives were explored to extend the service life of the dam and address the identified dam safety deficiencies to bring the dam into compliance with NCDEQ Dam Safety requirements.

While all of the alternatives address the identified dam safety deficiencies, each alternative has distinct advantages and disadvantages with respect to cost, service life, technical performance, and various other qualitative factors, as discussed herein. Based on our evaluation and consideration for each of these factors, the full dam replacement option, excluding replacement of the hydroelectric facilities, appears to be the most advantageous and lowest risk option.

(2) Alternative 1 - Cross–bracing: There are several technical concerns, disadvantages, and uncertainties with the cross-bracing alternative. While many of these issues could be mitigated through additional investigations, proper attention to critical design details, and thorough construction quality assurance, several of the hydraulic and structural performance concerns will still exist. The primary advantage of this alternative is the lower initial capital costs; however, consideration must be given to this alternative’s shorter service life and the additional long-term monitoring and maintenance costs that will be required to ensure safe functionality of the dam and appurtenances throughout the remainder of its service life.

(3) Alternative 2A - Upstream Infilling: This alternative presents very few advantages over the other alternatives considered in detail, and it also has the highest initial capital cost. Therefore, it was not included in the comparison summary below.

(4) Alternative 2B - Downstream Infilling: In terms of rehabilitation alternatives, the downstream infilling alternative appears to be more advantageous with respect to the project objectives and lower risk than the cross-bracing alternative; however, additional consideration should be given to the weight of the various factors included in this evaluation and the additional risks the Town may be willing to accept to implement the rehabilitation at a lower initial cost.

To further assist in the evaluation of a preferred alternative, we developed a ranking system to compare the relative advantages, disadvantages, and risks of the cross-bracing alternative (Alternative 1), the downstream infilling alternative (Alternative 2B), and the full dam replacement alternative. In following table, a percentage has been applied to each of the factors discussed above depending on their perceived significance or weight with respect to the evaluation of potential rehabilitation and replacement alternatives for the dam. The sum of the percentages for each factor totals 100 percent. In addition, based on the information gathered during the dam condition assessment process and this alternatives evaluation, a ranking between 1 and 3 has been applied to each factor for each alternative, with 1 being the most advantageous and/or lowest risk and 3 being the least advantageous and/or highest risk. A cumulative, weighted ranking was then calculated for each alternative with the lowest number theoretically representing the most advantageous and/or lowest risk alternative. A cumulative sum of the individual rankings was also calculated for each alternative for reference in the following table.

Based on the information included in the table above, the least advantageous and highest risk alternative is the cross-bracing rehabilitation alternative (Alternative 1), and the most advantageous and lowest risk alternative is the dam replacement alternative.

Comments: This will serve as both the initial and final public notice regarding the above‐described action funded by the FEMA BRIC program. Interested persons may submit comments, questions, or request a map of this specific project by writing to the Federal Emergency Management Agency, Region 4, 3005 Chamblee-Tucker Road, Atlanta, Georgia 30341, or by emailing FEMA.R4EHP@fema.dhs.gov. Comments should be sent in writing or email with the subject line “EMW 2021-GR-00169: Lake Lure Investigations” at the above addresses within 30 days of the date of this notice.

THIS NOTICE MAY BE REMOVED FROM PUBLIC VIEW ON THE 30^th DAY FROM ORIGINAL DATE OF POSTING

NOTICE WAS POSTED ON THE 30TH  DAY OF MARCH 2023