Wastewater Treatment Division

Wastewater Collection System

Once water is used, whether it comes from kitchens, bathrooms or sinks, it is collected in large pipes and conveyed to the Wastewater Reclamation Facility for treatment. The collection system includes gravity sewers, force mains, and pumping equipment to move the water in the lines from homes and businesses to the Wastewater Reclamation Facility.

It is important to understand that velocity or speed of the wastewater flowing through the collection system and treatment facility plays a major role in the treatment staff's ability to properly handle it. For example, the wastewater must flow at a velocity of at least two feet per second to prevent excessive material from settling out in the collection system. If this happens, blockages and sewer backups can occur.

Components of a Wastewater Collection System

BUILDING SEWERS, also known as PROPERTY SERVICE CONNECTIONS (PSCs), are what connect a building's internal wastewater collection system to the municipal sewer system. PSCs can connect to a lateral, main or trunk sewer line.

LATERAL AND BRANCH SEWERS are the upper ends of the municipal sewer system. Laterals dead-end at their upstream end with branch sewers collecting the wastewater from several lateral sewer lines.

MAIN SEWERS are collectors for numerous lateral and branch sewers from an area of several hundred acres or a specific neighborhood or housing development. They convey the wastewater to larger trunk sewer lines, to lift stations or to a neighborhood package wastewater treatment plant.

TRUNK SEWERS serve as the main arteries of the wastewater collection system. They collect and convey the wastewater from numerous main sewer lines either to a wastewater treatment plant or to an interceptor sewer.

INTERCEPTOR SEWERS receive the wastewater from numerous trunk sewers and convey it to a wastewater treatment plant. These are the largest diameter lines in the sewer system and the furthest downstream in the system.

LIFT OR PUMP STATIONS are utilized in gravity sewer systems to lift (pump) wastewater to a higher elevation when the route followed by a gravity sewer would require the sewer to be laid at an insufficient slope or at an impractical depth. Lift stations vary in size and type depending upon the quantity of wastewater to be handled and the height it must be lifted.

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