Selective Repairs of Digesters 2 & 3 at Humber Treatment Plant

Recent Bennett Construction Group Project

Contract Value: $7,951,810.00

Scope of Work:

• Cleaning of the interior existing sludge piping within each Digester and within the Digester Gallery, including high pressure washing.
• Refurbishment of sludge heat exchangers with gaskets and insulation replacement and cleaning and high pressure washing of associated sludge piping.
• Cleaning of interior of existing scum piping at the South Primary Clarifiers, Scum Pumping Stations, Access Tunnels, and Digester Gallery, including high pressure washing. 
• Decommissioning, selective demolition and removal of existing systems associated with the Digesters, digester gas mixing and conveyance piping,  gas handling equipment, and associated electrical and instrumentation equipment.
• Removal of existing waterproofing and gas proofing inside the Digesters and Digester Overflow Boxes
• Decommissioning, selective demolition and removal of existing sludge and scum valves, gas valves,  hot water pumps and valves, instrumentation, piping and appurtenances in the existing Digesters and Digester Gallery.
• Demolition of existing overflow box covers, telescoping valves, and instrumentation and appurtenances.
• Decommissioning, selective demolition and removal of portions of the digester hot water heating system, including three-way control valves, hot water recirculation pumps, piping, instrumentation, and appurtenances in the existing Digester Gallery. 
• Removal and replacement of all waterproofing, gas proofing, insulation, and protective coating systems on two existing Digesters and Digester Overflow Boxes.
• Structural and architectural repairs to interior and exterior concrete at two existing Digesters and associated digester overflow boxes.
• Replacement with new of digester gas mixing equipment for two existing digesters including packaged bubbler equipment, instrumentation, and piping modifications.
• Replacement with new of digester gas safety equipment for two existing digesters, including two counterweight pressure relief hatches on each digester, and one 3-way selector valve.
• Refurbishment of roof mounted access hatches and viewing ports, including gasket replacement, on two existing digesters.
• Refurbishment of digester overflow boxes including replacement of access hatches, and replacement of telescoping valves and level instrumentation. 
• Replacement with new of two hot water recirculation pump sets (2 pumps per set), associated 3-way hot water control valves, and associated high pressure switches, for two digester sludge heat exchangers in the Digester Gallery, including associated wiring and pump control panel modifications.
• Replacement of sludge valves in the Digester Gallery. 
• Inspection and pressure testing of exterior gas piping on two existing digesters, including removal and replacement with new of gas piping insulation. 
• Pressure and leakage testing of two existing digesters.
• Inert gas purging of two existing digesters and associated gas piping.
• RPU and SCADA system modifications. Integration of the new and upgraded system into the existing Humber Treatment Plant RPU and SCADA systems.