After a competitive review process, Marathon hired Weiler Engineering (Punta Gorda, FL) to design a treatment solution. According to Zully Hemeyer, Marathon utilities director, "we chose a decentralized network of collection systems and small, advanced treatment plants serving various sections of the community." "That proved to be the most cost effective option." After visiting a few plants, the city decided on the OMNIPAC® SBR to achieve a cost effective solution in a small footprint with a design to installations timelime of 12 months for each system.
The OMNIPAC SBR system is a factory-built, Davco™ field-erected aboveground structure composed of pre-fabricated steel rings utilizing OMNIFLO® SBR technology. The outer diameters of the four units at Marathon range from 60 to 105 feet. Each unit contains three SBR basins with jet aeration systems to mix and aerate the mixed liquor. Each basin includes a solids-excluding floating decanter for effluent withdrawal, as well as an influent manifold for even distribution of influent into the sludge blanket. Waste sludge pumps for sludge withdrawal are also located in each basin.
The design also includes a post equalization basin which is covered to minimize algae growth and animal waste in the effluent water, and an aerobic digester. The effluent equalization tank includes a submersible pump for pumping the SBR effluent to the filters and chlorine contact basins. Incoming wastewater passes through fine screens ahead of the SBRs. A SCADA system provides remote monitoring and control of the entire treatment system.