locations

Location

Black Mountain, NC

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P&J Role

Prime Contractor

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Completion Date

Ongoing


Project Description

The North Fork Spillway and Embankment Improvements Project is designed to update the North Fork Reservoir dam, which was originally built in 1955. Advances in technology since its construction has allowed the City of Asheville to determine ways to make the dam more resilient in the face of possible but unlikely storm events. The dam will be raised by 4’, with added earth buttressing to reinforce seismic stability, and the principal spillway will be improved while a new auxiliary spillway is constructed.

Project Highlights

350,000

CY Earth and Rock Excavated

15,000

CY Structural Concrete

200’ by 600’

Spillway Constructed

P&J has begun these improvements as of November 2017. The main scope of work is the construction of the new auxiliary spillway, which is approximately 200’ wide and 600’ in length. The control section of the spillway will be made up by a Hydroplus design called Fusegates. Earth and rock had to first be excavated to get to the subgrade of the spillway, and material excavated from the spillway will be used to buttress the two existing earthen dams from a 2:1 slope to a 2.5:1 slope. A new seepage collection system is also being installed prior to the placement of the buttress material.

NorthFork
NorthFork

Due to the placement of the buttress material, the conduit that supplies raw water to the water treatment plant will have to be extended. The extension will be achieved by casting in place a structural concrete vault that will house a new 36” ductile iron pipe. In order to not interrupt plant operations, a temporary pumping system will be installed during the conduit extension. Modifications will be made to the existing intake tower, and the principal spillway will be rehabilitated, including the installation of new Obermeyer spillway gates.