Challenging tasks solved easily

The Goal

To increase capacity at the already-upgraded digester tanks
Due to requirements to expand the capacity of each of the four tanks, the top three feet of concrete had to be removed from the existing tanks and then replaced with new stem walls that were poured eight feet on top of the existing concrete.

The Project

Summary:
Located outside of Columbus, Ohio, the Jackson Pike Wastewater Treatment Plant is one of two facilities that treat approximately 188 million gal. of wastewater produced daily by the city of Columbus and 25 surrounding communities.

Since the plant was founded in 1935, Jackson Pike has undergone multiple upgrades. Most recently, two 70’-0 digester tanks and two 70’-0 secondary clarifiers were designated for upgrade to meet the need for increased capacity in the plant. All four tanks were constructed primarily below grade with only a few feet of concrete wall exposed above the grade level. 

Challenge:
The challenge in removing the old concrete and completing the expansion was further complicated by the interior shape of the tanks. The base of each tank was conical shaped on the inside, thus making it almost impossible to provide any type of scaffold platform to provide access when working from the inside of the tanks. 

The Solution

1. Installation only possible from the outside
   After being awarded the project, Kenmore met with MEVA to explore different options to consider for completing the upcoming project. Since Kenmore wanted to provide workers access and to have the ability to brace the formwork from inside the tank, MEVA suggested and designed preassembled KLK platforms conceived to fit the radius and that could be flown and landed onto the KLK shoes that would be mounted on the inside of the existing radius concrete walls.

   To complicate the task further, the platforms had to be installed without any workers present inside the tank during installation. Prior to the platforms being installed, Kenmore had to lower workers down inside each tank from a crane-mounted personal basket to provide the workers access to install the shoes that the KLK brackets would require to be landed on. Furthermore, Kenmore had to install additional anchors that would be required to mount straps for potential wind loads that could be encountered once formwork was placed on the platforms
    

2. Off the truck and mounted to the walls
   After the KLK shoes were installed and the straps for the wind load were in an accessible position, the KLK platforms were lowered into the tank and placed onto the shoes, all while the workers remained outside of the tank. Once workers were able to gain access to the platforms, they immediately secured each platform with the straps to provide protection from the potential wind load forces. Since the KLK platforms were delivered to the site preassembled by MEVA, the platforms were flown directly off the truck and mounted to the walls inside the tanks.
    
3. Pre-installed MAR formwork
   Once the platforms were in place, Kenmore selected the MAR (MEVA Adjustable Radius) as the wall formwork system to be used to form the new stem walls. MEVA provided the labor to preassemble the MAR formwork system having preset the radius and installed the plywood facing prior to being sent out to the jobsite. The MAR system allows for the radius to be adjusted from as large as 75ft. down to an adjusted radius of 20ft. For this project, Kenmore selected enough formwork to completely form two of the four tanks. According to project superintendent Heath Wilgus, successful results from previous unique projects made MEVA a natural choice when deciding on their formwork partner.

   

The Outcome

Preassembling the wall formwork allowed the contractor the ability to fly the formwork off the truck and directly onto the wall, again helping keep their schedule on track. The walls were then poured in three sections. Once completed, the formwork and platforms were recycled one time to the second set of tanks and the process was completed again to deliver a successful outcome. 

Featured Products

• KLK climbing formwork
• MAR (MEVA Adjustable Radius)

Client:
Kenmore Construction

Project:
Upgrade of Jackson Pike Wastewater Treatment Plant

Location:
Columbus, Ohio

Engineering:
MEVA Formwork Systems, Inc.