The City of Lewisville’s expansion at the CR Feaster Water Treatment Plant included both construction of a new 2.0 MG Prestressed Concrete Clearwell as well as modifications to the existing three (3) conventionally reinforced cast-in place concrete tanks at the plant. The work in the first tank, Clearwell No. 3, included a new fabric baffle wall system, installation of a new 42″ through wall outlet pipe, and re-routing the existing 36″ outlet. The 2.0 MG Clearwell No. 3 is 160 feet in diameter with a 14 foot wall height and also features a flat slab roof supported by interior concrete columns.
DN Tanks Concrete Tank Services was contracted to design and install the proposed tank modifications. Since no existing tank information was available, DN Tanks was required to perform a full investigation of the tank prior to designing the new structural modifications. DN Tanks experience and expertise in watertight tank penetrations and structural modifications to existing concrete tanks provided the City with a single source responsibility for design and construction.
The 36″ outlet pipe was re-routed 90 degrees inside of the tank around the tank wall in order to allow the clearwells to run in both series and parallel, giving flexibility to the City. The new 42″ outlet through the wall required a custom 52″ core bit and allowed for connection to the new clearwell being constructed by DN Tanks.
A fabric baffle wall system consisting of eight walls was installed to provide additional contact time through the clearwell and improved the disinfection process.
The new improvements were completed within budget and met the tight schedule required to return the tank back to service prior to the high demand water season.