North Fork Dam Improvement Project
During a well-attended November community meeting at the Black Mountain Library there was discussion of construction impacts, including blasting associated with site clearing. Other impacts include created traffic for construction trucks mobilizing for the project. Blasting began April 2 and is expected to last 2 to 3 months once the excavation for the new spillway construction begins. We would like to remind nearby residents that this type of blasting (into the ground) differs from the type of blasting heard from the nearby quarry.
Other blasting details:
- Blasting will be conducted between the hours of 9:30 a.m. and 3:30 p.m.
- Typically there will be one to two blasts a day. These will be followed by one to three days of excavation.
- A series of sirens will proceed and follow each blast. These typically will be a one-minute series of audible signals prior to the blast, followed by a prolonged signal after the inspection of the blast area.
Thank you for your patience as we work on this important dam improvement project. Find more information in the presentation linked below, including slides from the November community meeting presentation.
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 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.
August 22, 2016 Public information session, Doubletree Biltmore Village, 115 Hendersonville Road, 5:30 p.m.
August 23, 2016 Public information session, St. John's Episcopal Church, 290 Old Haw Creek Road, 6:30 p.m.
August 24, 2016 Public information session, Riceville Community Center, 2251 Riceville Road, 6:30 p.m.
August 25, 2016 Public information session, Bee Tree Fire Station Community Room, 510 Bee Tree Road, 6:30 p.m.
Fall 2016 Environmental consultant submits environmental permitting package to US Army Corps of Engineers and NCDEQ
Winter 2016 Engineers complete design, submit design package to NC Dam Safety for review
Spring - Summer 2017 Respond to agency comments on Environmental and Dam Safety permits and receive approvals as required.
Summer 2017 - Bid the construction work for the North Fork Reservoir Spillway and Embankment Improvement Project.
October 2017 - Bid contract awarded to Phillips & Jordan
November 20, 2017 - Construction update meeting: 6 p.m., Black Mountain Public Library, 105 N. Dougherty Street, Black Mountain. Presentation from Meeting
December 2017 - Construction mobilization to begin
Winter 2019 - Anticipated completion of construction for the North Fork Reservoir Spillway and Embankment Improvement Project.
Frequently Asked Questions - UPDATED 04/11/2018
This video from HydroPlus demonstrates a scaled model of a labyrinth fuse gate system activating. This model is similar to a fuse gate that will be placed at the North Fork Dam auxiliary spillway.
This video demonstrates the type of blasting with delay charges that will be used at the North Fork project site. This project example has a similar geologic setting and rock type to the North Fork project. From it, you can examine what a typical blast looks like and sounds like within close range to the shot.
This video was from an April 9 blast. The angle is from the top of the coffer dam (temporary dam) looking down at what will become the auxiliary spillway - away from the lake.