News

The St. John's Harbour is a receiving water body for sanitary and storm water sewage from St. John's, Mount Pearl and Paradise. "It is estimated that approximately 120 million liters of raw sewage and storm water enters the Harbour daily through the City's sewer infrastructure. During wet weather storm events, the Harbour can receive 4 to 5 times the daily amount from its sanitary sewage system." The City of St. John's Harbour Clean Up Program aims to capture and treat sanitary and storm water sewerage entering the Harbour through its combined trunk sewers.

The construction of the Riverhead Wastewater Treatment Facility (RWTF) is one component of the City of St. John's Harbour Clean Up Program. The new facility will be a Primary Treatment Facility with the potential for expansion to Secondary / Enhanced Chemical Treatment as dictated by future Harbour water quality results. The RWTF has been subdivided into six main areas. In general each area represent one or more main plant functions as briefly described below.

Area 1 - New & Existing pumping stations; this is the head of the plant where flows from the combined trunk sewers enter the facility. Here the flows are screened & then pumped into a discharge/inlet channel which flows to the Grit Tanks of Area 2.

Area 2 - Aerated Grit Removal; grit is removed and flows passing through enter the Primary Influent Channels on the way to the Clarifier Tanks of Area 3.

Area 3 - Primary Clarification; scum and sludge are removed and pumped to the Digester Tanks of Area 5. The majority of the flow passes through and enters the Primary Effluent Channel which then flows into the Chlorine Contact Tanks of Area 4.

Area 4 - Chlorination and Dechlorination; this is the last stop for effluent before it leaves the facility. Here chlorine is added to disinfect the effluent over a period of time. Before final discharge into the Harbour chlorine is removed with the addition of liquid sodium bisulfite.

Area 5 - Digestion Tanks; through a process of anaerobic digestion the scum and sludge from Area 3 is digested. The digested sludge is dewatered in Area 6 by dewatering centrifuges. The digestion process produces gas which is collected and used to fire the boilers, located in Area 6, which heat the entire facility.

Area 6 - Sludge dewatering, Boiler plant and Administration Building.

In May 2006 the City awarded the RWTF construction contract to Olympic Construction in the amount of approximately $62M. The current construction schedules indicate project completion on time before the end of November 2008.