Bellevue, NE
WLA was selected by the City of Omaha to evaluate alternatives for replacement of the primary clarifier mechanisms at the Papillion Creek Wastewater Treatment Plant. This plant operates eight primary clarifiers that are 115 ft in diameter and have a side-water depth of 6 ft-10 in. Each clarifier is covered with an aluminum dome for odor control. After presentations from numerous clarifier mechanism manufacturers, a Basis of Design was developed. The concept will then be applied to all future primary clarifier mechanism replacements. Primary Clarifiers No. 5 and 8 were selected to be replaced in 2009. The clarifiers were drained and inspected for concrete deterioration. The top 26 in. of the tank walls will be repaired and re-coated with hydrogen sulfide resistant materials. Fiberglass materials will replace the severely corroded aluminum weirs and baffle plates. WLA prepared drawings and specifications that will be used to describe mechanism replacement.