OWEA – Engineering Excellence Award

The focus of this award is on a project and not a person. The selected project must have been in operation for a period of one (1) year and not more than five (5) years.

After bids for the City of Defiance anaerobic digester rehabilitation project came in too high, the city decided to reinitiate the project within a design-build structure. Mosser Construction was the contractor and AECOM was the engineer. The result of the design build effort was a fully functional digester complex with more upgrades than originally scoped while maintaining the City’s project budget. The design-build process allowed the Contractor, Engineer, and owner to discuss changes in a timely manner and get expedited approval of changes. The digester upgrades improved mixing by replacing the gas lance mixing system with a bottom mixing system. The new mixing system also shreds any large debris that may get into the digesters. The methane gas storage increased to a capacity of 35,000 cubic feet. The quality and quantity of the methane gas increased allowing the boiler to run hotter on digester produced gas for longer periods of time.