Solution
Our team was brought in to design and provide support of construction for the wet-weather sanitary storage facility. Our team quickly determined a variety of infrastructure components would need to be implemented to create a successful storage solution. The storage facility has two partially buried circular storage tanks — each made of concrete and big enough to hold 4 million gallons, for a total volume of 8 million gallons. It also includes an influent pump station with eight raw sewage submersible pumps and a total capacity of 54 million gallons per day and a service water pump station to provide water for the facility’s washdown system and yard hydrants.
Sustainability was a major theme throughout the design and construction of the facility. To achieve efficiency, the facility’s tank domes were constructed to have internal drainage that pushes stormwater to the service water cistern. Rainwater is collected and stored in the service water cistern, which supplies the washdown system. Such reuse eliminates the need to purchase potable water for such on-site needs.
Additionally, the facility components include a robust diversion structure, a dewatering control vault, consolidation sewers, force mains, an odor control system, a control building, yard piping, duct banks, instrumentation and controls, and other related infrastructure. The infrastructure the design team recommended represents a unique approach to solving a collection systems issue, while improving local water quality and public health.
The project site had limited land between residential and light industrial properties. A line of trees separates a residential subdivision from the project site, with residential and light industrial properties across the street from the Gravois tanks. Such stakeholders had concerns about the potential for tanks-related size, odor and appearance issues. Our team created a community and stakeholder group consisting of elected officials, neighborhood leaders and surrounding business owners to address these concerns.
The group’s input and involvement during design of this project proved crucial to success. The group met with the design team to select the fence type, tank color and finish, site lighting, finished landscaping, and public parking for the community to access a nearby walking trail. The design team maintained the lines of trees to provide a natural screening between the storage facility and the residential subdivision. The design used dual storage tanks to fit the limited footprint and provide operational flexibility for MSD staff, allowing for regular maintenance without impacting service.
