Award of Excellence: Strengthening Category
Camp Verde Wastewater Treatment Plant Repair
Camp Verde, Arizona
Submitted by Truesdell Corporation
Camp Verde Sanitary District of Yavapai County
Camp Verde, Arizona
Structural Technology Consultants
San Diego, California
Lyndhurst, New Jersey
A newly constructed wastewater treatment facility in Camp Verde, AZ, was identified as being underdesigned when large cracks formed on two of the concrete walls during its initial water test.
The 128 x 92.5 ft (39 x 28 m) water treatment tank is a reinforced concrete wall and slab system comprised of 10 individual cells. The concrete is reinforced with steel reinforcement. The walls are 18 ft (5.5 m) tall and some reach an unsupported length of over 90 ft (27.4 m). The large spans result in high bending forces, which must be developed without allowing cracking.
Evaluations of the structure determined that filling the tank would overload the structural walls due to insufficient horizontal reinforcement at the wall intersections. A conventional repair method had been previously developed using reinforced concrete bolsters at all of the intersecting walls and at the wall-to-slab connections. This option was extremely costly and would have resulted in a substantial reduction to the tank’s capacity.
As a result, a new design-build team was brought in, including experts in concrete repair and a consulting structural engineer. The team was tasked with developing an alternate strengthening solution that considered the strength requirements associated with various deficiencies, load conditions, and future operations while maintaining the desired volume capacity of the tank, all with minimal impact to the construction schedule.
After weeks of evaluation and design work, the strengthening project was completed in approximately 2 months. The city of Camp Verde is delighted with the repairs to their facility, and this structure has been in service for several months. At several junctures, the project was nearly scrapped, and if not for the creative curtailing of the carbon fiber-reinforced polymer and the unique application of bolts and steel plates, combined with the appropriate use of traditional concrete dowels, this project would not have succeeded.