Tannery Knob Water Storage Tank and Water Transmission Line

Our team provided survey, design and construction administration services for the 5-million-gallon Tannery Knob Water Storage Tank and more than 2,000 linear feet of a new 20-inch water transmission line. The original 3-million gallon Tannery Knob Reservoir was constructed in the 1930s and served Johnson City for more than 80 years. Phase I of the project consisted of removing the existing reservoir and site preparation work for construction of the new tank.

Design challenges associated with site preparation included steep topography, limited area

for installation of a new pad and site excavation, which consisted primarily of shale. The challenges were met by extensive use of a rock anchor and shotcrete system to stabilize exposed vertical rock faces around approximately half of the tank perimeter, and installation of a precast concrete “Redi-Rock” retaining wall system on the lower portion of the site.

Phase I was completed in 2017 at a cost of approximately $1.1 million. Phase II of the project

consisted of the construction of the new 5-million-gallon prestressed concrete storage tank and

connection of the tank to an existing valve vault onsite. The tank was completed in August 2018 at a cost of approximately $2.5 million.

Phase III, which was completed in 2019, included the installation of approximately 2,200 linear feet of new 20-inch diameter ductile iron pipe water transmission line to supply the new tank and replacement of the existing reservoir valve vault with a new precast concrete vault with a new altitude valve.