Collection System

The wastewater treatment process begins with the collection of waste streams from homes, businesses and industrial complexes.  The streams feed into what is known as the collection or drainage system which transports the wastewater to the wastewater treatment plant for processing.

The collection system is comprised of pipes, junction boxes, lift stations and associated equipment that channel raw wastewater to the plant.  In many cases, the collection system will also serve to collect storm runoff.  Systems that convey storm runoff and waste streams are known as combined sewer overflow (CSO) systems.

Individual homes are connected to the collection system with the public service connections (PSC) to the main sewer line.  Sewer lines come together from different directions into a junction box.  Junction boxes combine the flow from main lines into a much larger flow heading towards the wastewater treatment plant.

The size and pumping capacity of each lift station will be dependent on the maximum estimated flow rates at each station.  Where the flow rates are relatively low, lift stations are quite small.  The stations closer to the plant can become very large, requiring several large capacity pumps to provide adequate flow capacity.

All lift station designs must consider flow rate changes due to demand variations, such as time of day and storm surges.  If a collection system is configured for CSO, there may be a series of large ancillary storm pumps in these pumping stations.