This project required complete rehabilitation of four digesters and the interconnecting galleries. Only one digester could be taken out of service at a time, requiring highly coordinated and phased effort. Plan called for covers to be removed from all four digesters. Two would be replaced with steel fixed cover, two to be replaced with membrane covers. Upon inspection of the first digester the concrete covers were found to be in excellent condition. With this, Goodwin Brothers proposed reusing the two of the existing covers, saving the client $600,000.
Our scope of work included first cleaning of the digesters of residual grit and screenings. The existing gas mixing system was replaced with liquid mixers powered by chopper pumps located in the lower level gallery. The interior of each digester was protected with high performance coatings, interior and exterior of concrete covers that remained were coated, remaining covers were replaced with membrane gas holders. Other components included replacement of existing hot water boilers and generators powered by digester gas. The last piece was to replace the existing single flare with a dual unit to flare off any excess gas.
