The City of Frankfort, Kentucky is a true river city nestled in the heart of bourbon manufacturing and horse country – and is now the owner of a CROM 10.0-MG Wet Weather Storage Tank. Also referred to as a Flow Equalization Tank, the tank is primarily used when a major rain event occurs and inundates the sanitary sewer system. Flow inundation is a problem for many water sewer systems; the causes for this include: leaks in pipes and manholes, low-lying manholes prone to flooding, unauthorized sewer taps draining home foundations and gutters, among others.
Historically, high flow rates of untreated (although diluted) wastewater would create a “plug” of flow that would pass quickly through or bypass the plant and empty directly into the Kentucky River. The Clean Water Act established the basic structure for regulating quality standards for surface waters and made it unlawful to discharge any pollutant from a point source into navigable waters. EPA enforcement of this act has resulted in wastewater utilities launching improvement projects to mitigate these Sanitary Sewer Overflows (SSO’s). CROM Wet Weather Tanks serve as a cost effective solution for SSO’s by providing a large volume container to hold untreated wastewater until high flow conditions subside. The stored wastewater is then fed through the wastewater plant at a controlled rate for treatment, testing, and discharge.
The tank was built at the existing plant (located in the river’s floodplain) in poor, silty soil conditions. This required the tank to be supported by 253 – 30” diameter drilled piers bearing on bedrock that was roughly 50’ deep. End bearing drilled piers have a very high capacity which allows for wide spacing of piers.
However, long spans between piers require a strong, highly reinforced floor. The 192’ outside diameter floor had an average thickness of 29” and sloped almost 6’ to the center drain. This was a very large monolithic pour for the Frankfort area and one plant alone could not supply enough concrete to keep up with our demand. Two competing concrete companies coordinated an agreement and together they were able to supply approximately 2,800 CY of 4,500 psi concrete for the floor. Ken Fogg and his crew traveled from north Georgia to help place over 550,000 pounds of steel and to assist Jose Zarate’s crew. Starting at 2:00 AM, the pour took about 14 hours.
Although CROM field crews are used to generally muddy conditions, the crew on the Frankfort site encountered some exceptionally wet weather. With the work road approximately 5’ below the existing grade, forming a bowl; stone had to be supplied to the site regularly by the general contractor to ensure that production kept moving.
Another job well done thanks to Superintendents Jose Zarate and Ken Fogg, their crews, Project Manager Brett Bohannon, and Area Manager Tal Mincey.