Specifications include, but are not limited to: The project consists of: Cleaning Primary Digester No. 1 at the City of Billings Water Reclamation Facility. This work includes but is not limited to: hydro-washing digesters, removing and dewatering sludge, removal of hair, grease, plastics, soil, struvite, sediments, and all other debris present in Primary Digester No. 1. Additionally, all three sets of the roof supported gas lances will be replaced. Contractor is responsible for removal of existing gas lances, fabrication of new gas lances (replacement in kind), and installation of new gas lances. The mixer access opening will also need to be modified to change from a 2-piece hinged access door to a 1-piece bolted access cover. After cleaning, gas lance replacement, and mixer access opening modifications, the seal around the perimeter of the tank roof (between the carbon steel roof and concrete wall) shall be removed and resealed, and the carbon steel roof shall be sandblasted and recoated with paint.