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.