Under the Additional Services Task in the Annual Retainer Agreement, the Huntington Sewer District requested H2M provide engineering services for the replacement of existing rotating biological contactors (RBCs) at the District’s scavenger wastewater pre-treatment facility.
The purpose of the scavenger waste pre-treatment facility is to reduce the concentration of BOD and suspend solids from septic tank pump-outs before the wastewater is conveyed to the Huntington Sewer District treatment plant influent wet well to allow additional treatment. The pre-treatment facility has a design flow of 86,000 gallons per day (gpd).
The pre-treatment facility includes four RBCs. The RBCs have been in service for about 30 years and have reached the end of its useful life. Over the life of the equipment, the shafts on the first two RBCs had been reworked and shaft bearings had been replaced several times.
H2M prepared the technical specification used by the District to bid the purchase of replacement RBCs. The specification included requirements for the shaft, media, bearings, and drives, along with manufacturer delivery and start-up services. The first two RBCs were replaced in 2016. Replacement of the third RBC will be completed in 2018. After each bid award, H2M also reviewed the manufacturers submittal. Removal of the existing and installation of new RBCs has been done under a District requirement contract.
