DN Tanks prestressed concrete tanks are constructed to last for generations and beyond. Whether buried, partially buried or above ground, all of our circular prestressed concrete tanks are built in accordance with AWWA Standard D110.
Our goal is for each tank to serve as designed, be favorably accepted by the local community, withstand seismic and environmental challenges, and provide longest service life – all with negligible maintenance requirements. The design and engineering of each tank is customized based on the site, tank size, exterior enhancements and other common variables. Click here to learn more about our Support Services »
Our tanks are constructed utilizing specialized methods and exacting quality control to deliver long-term assured service with negligible maintenance. Over the decades, we have emerged as the industry’s leader in areas including cast-in-place and precast concrete tank construction, solid wire and strand prestressing, electronic prestressing control and monitoring, automated shotcrete, seismic design technology, and many more.
Site work and foundation preparation are in accordance with the site plan and the site specific geotechnical report.
A highly reinforced, membrane, concrete floor effectively poured in the minimum number of pours is most common. DN Tanks recommends monolithic placement of the floor when possible. Alternatively, each floor joint incorporates a waterstop and galvanized or epoxy coated bars span the joint. Our expertise expands to other floor systems as well, such as a structural floor or steep conical floor sloped to the tank center.
We construct tank walls utilizing either cast-in-place techniques (Type I) or precast panels (Type III). Our walls are always cast full height and in equal circumferential sections, curved to the specific radius of the tank and with no horizontal joints.
Type I Tanks: Cast-in-Place
- Wall forms are carefully curved to the radius of the tanks.
- The cast-in-place concrete corewall is cast continuously full height and in equal circumferential sections.
- Vertical prestressing tendons are cast inside the wall to provide compression that counteracts the effects of differential dryness and thermal loads.
Type III Tanks: Precast Panels
- A steel diaphragm acts as a water barrier in the finished tank to assure watertightness. It also acts as the bottom casting form for the wall panels.
- Wall panels are precast on-site in casting beds that are custom formed to the curvature of each tank.
- The wall panels are placed onto bearing pads outside of the encased waterstop. Set approximately 7 to 10 inches apart, the wall panels form a series of open slots, which are later closed.
Concrete Dome: Freestanding, spherical, low-rise concrete dome with no interior columns, or a low profile, column supported flat slab concrete roof are most common. Other roof types or open top tanks can easily be accommodated.
Columns Supported Flat Slab: A concrete, two-way, flat slab roof with a slight upward slope to the tank center is cast in the minimum number of pours, similar to the floor. A grid of equally spaced round columns supports the flat roof.
Wire-Winding: Following tank concrete placement, the tank wall is circumferentially prestressed with continuous high strength steel. Circumferential prestressing is the heart of the tank structure, placing the tank wall in permanent compression thus resulting in the most durable tank structure. A high-pH shotcrete is applied over the exterior prestressing, which passivates the steel, providing permanent bond and corrosion protection.
- Reels of wire are spliced together to create continuous prestressing from top to bottom.
- The wire force is measured in place to verify it is within specified tolerances.
- The wire is encased in shotcrete by an ACI certified nozzleman.
Machine Wrapping: Our state-of-the-art circumferential prestressing equipment is able to perform multiple sophisticated tasks with one simple, automated and quality controlled unit.
Hydroblasting: Shoots at 40,000 psi. Environmentally friendly. Removes oils and roughens surface.
Strand Wrapping: 7-wire galvanized strand. Wraps at 14,950 pounds. Differential gear gripping head.
Automated Shotcrete: Application provides efficiency for large surface areas.
Plastic Wrapping: Water cured for 7 days.
Accessories, such as roof and wall access hatches, interior and exterior ladders, vents, safety railings, level sensing equipment, or specialized security hardware, are available to meet specific project requirements.