North Fork Dam Improvement Project

Happening Now

After more than two years of construction, the North Fork Dam Improvement Project is nearing completion. This will deliver to our community a safer dam with more capacity to hold water from the reservoir and one that is better enforced against potential seismic activity.

It is scheduled to be fully operational as of October 31.

As this project nears completion, the City of Asheville reached out to the community on the City’s Virtual Engagement Hub, asking what remaining questions people may have. On August 17, the City will posted a pre-recorded presentation about this project that provides an overview of the dam improvements and answers the questions submitted. See the presentation below.

Accomplishments since Spring 2018

Due to excessive amounts of rain in 2018 and winter 2020 the North Fork Dam Improvement Project has been somewhat delayed. Project completion is now on track for late summer 2020. Of note, the property received over 90 inches of precipitation in 2018, causing construction delays.

Progress update for the auxiliary spillway and dam improvements:

75% of the buttressing of the main dam is complete.
Water / run-off collection system is complete on the main dam.
Principal spillway chute overlay is complete.
Work to remove the existing tainter gates, installation of obermeyer gate, and pouring of concrete weirs on the principal spillway is 75% complete.
Improvements to the intake tower are essentially complete. The tower now sports a red metal roof with a longer life cycle than the traditional shingles.
Extension of the conduit and tunnel are complete.
Auxiliary spillway:
- Fusegates were completed in eight (8) weeks in the spring of 2019.
- Over 50% of the spillway chute is complete. Walls are still being constructed.
Surrounding invasive vegetation (Silvergrass, Kudzu) treated with herbicide is 75% complete.
All the equipment related to the temporary raw water by-pass (pumps, barges, piping, and electrical panels) has been removed from the reservoir and dam, allowing for normal operations to resume.

Background

In a continued effort to prevent significant damage in the event of a natural disaster (flood or earthquake), the City of Asheville, in conjunction with consultants from Schnabel Engineering, have identified proactive improvement measures to be taken at the North Fork Reservoir to protect and improve critical infrastructure. The North Fork Reservoir and Water Treatment Plant serve as the City’s primary drinking water source, providing 70% of Asheville’s water. With so many people, businesses and industries dependent upon this critical natural resource, special care and proactive measures need to be taken to ensure our water source and infrastructure are protected.

Planned modifications at North Fork Reservoir include:

raising the dam by 4 feet;
improvements to the principal spillway and the addition of an auxiliary spillway;
modifications to the raw water piping through the dam and to the water treatment plant; and
earth buttressing to reinforce the main dam and saddle dam for seismic stability.

The bid for construction services was awarded in October 2017 to the contractor Phillips & Jordan, and construction is set to begin this winter.

Once completed, the dam will be able to better withstand inflow from severe storm events, as well as add capacity to the reservoir.

The dam, located at the North Fork Reservoir, was originally constructed in 1955 and its design was based on available information and industry standards for that time. In the last decade, advances in technology and data analytics have enabled engineers and scientists to better model and predict certain weather events and environmental conditions. More accurate information is available now than ever before and, due to that, best practices for modeling and simulating certain conditions have greatly improved. This information has allowed the City’s consulting engineers to simulate a variety of possible scenarios for extreme storm events. These models and design parameters are required by the North Carolina Department of Environmental Quality, Dam Safety, of all regulated dams. Based on the outcomes of these scenarios, the engineers have identified improvements to help protect the reservoir, the water source, and nearby residents in the event that one of these unlikely but possible events were to occur.

Emergency Action Plans

The City has had an Emergency Action Plan (EAP) in place since the 1990s – and updated in 2006 – and has conducted training and “table top exercises” among senior staff within the City and surrounding communities’ emergency responders. Training topics covered what conditions constitute activating the EAP and how emergency responders will receive the information so they can be prepared, should an emergency associated with flooding arise.