Cape Breton Regional Municipality (CBRM) retained Dillon to complete the design, tendering and contract administration of this wastewater collection and treatment system constructed in the Cape Breton Regional Municipality (CBRM). The system includes a SBR wastewater treatment plant producing a secondary level effluent. Other major components of the treatment system include fine screens, vortex grit removal, sludge dewatering and UV disinfection. The plant discharges to an existing outfall located in the Atlantic Ocean.
The project was a priority for CBRM due to a history of closures at Dominion Beach resulting from the discharge of untreated sewage into the coastal waters surrounding the beach. To deliver the raw sewage to the plant, seven outfalls were intercepted and flow was diverted to the plant using five sewage lift stations and a combination of gravity and pressure sewers. The gravity sewers range in size from 300 mm to 600 mm, while the pressure sewers have diameters between 150 mm and 300 mm. Considerable portions of the piping system are located on private lands which resulted in considerable effort associated with land owner approvals. The sewage lift stations are all submersible pump type with each station including either three or four pumps, ranging in capacity from 21 litres/second (L/s) to 45 L/s. A consistent architectural approach was used for the pump stations and treatment plant.
Ultra-violet radiation was incorporated in the STP design for disinfection of the plant effluent. The UV system is designed to permit disinfection of the secondary effluent as well as the screened combined sewer overflow. To further decrease the chance of raw sewage discharge to the ocean, emergency power generation was installed at the treatment plant and all pumping facilities.
As a testament to the importance and success of the project, swimmers were back at the beach during the summer of 2010.