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Pump Stations

The Norwalk Water Pollution Control Authority (WPCA) operates and maintains 22 pump stations with approximately 6.5 miles of associated force mains. Pumps stations are critical infrastructure used to transport wastewater from a lower elevation to a higher elevation in locations where it cannot travel by gravity. A pump station is typically designed to collect wastewater from a gravity pipeline into a below ground wet well chamber. Once the wastewater reaches the designated level in the wet well, the pumps turn on and lift the wastewater through a pressurized force main that discharges to a gravity manhole where the flow can continue to travel by gravity.  

Pump Station Facts:

22 Pump Stations:
1931 – Fort Point Pump Station built
1950s – 1970s – 19 stations built
1980s – 2 stations built

Type:
Wet well / dry well – 17 stations
Submersible – 5 stations

Sizes:
Range from 0.2 mgd to 10 mgd

Operations and Maintenance (O&M)

On September 16, 2019, the City and Veolia Water Contract Operations USA, Inc. (Veolia) entered into a 10-year Wastewater Treatment System Service Agreement for operations, maintenance, and management of the City’s wastewater treatment system. Veolia began operating the system on May 17, 2020. Under the agreement, Veolia is responsible for the O&M of the sanitary sewer collection system, including pump stations, force mains, pipes, siphons, and related manholes (MHs) and collection system appurtenances. Veolia developed an O&M program to optimize human and material resources to provide efficiency and dependability for the City of Norwalk.

The Veolia Team performs weekly pump station inspections and maintenance activities. All 22 pump stations are connected to the Supervisory Control and Data Acquisition program (SCADA) which allows for continuous monitoring, operation, and alarm notifications of all pump stations. If an alarm is received, the Veolia staff is notified immediately and is able to respond to resolve the issue.

Types of Pump Stations

The 22 pump stations are mainly concrete structures that are equipped with electrical equipment including emergency generators, pump controls, and heating and ventilation. There are two types of pump station configurations: wet well / dry well and submersible pump stations.

Well / Dry Well Pumping Station

Wet well/ dry well type pumping stations maintain a separation between the “wet” side meaning wastewater flows, and the “dry” side meaning pumping equipment. The larger stations are often built as one complete cast-in-place concrete structure, designed for regular access by operators. Norwalk has seventeen of these types of stations.

Submersible Pumping Station

Submersible-type pump stations consist of the pumping equipment inside the wet well, with controls and other equipment housed in a separate structure or above grade. Norwalk has five submersible-type stations.

Pump Station Improvements

The Norwalk WPCA has been proactive in working with consultants to conduct projects to upgrade and maintain the pump station infrastructure. The Pump Station Asset Management Plan was prepared in 2019 and provided detailed information and recommendations for each pump station:

  • Infrastructure age / condition (mechanical, electrical, structure, etc.)
  • Future flow and Capacity Evaluation
  • Force main capacity
  • Climate Change and Flood Impact Mitigation
  • Energy Efficiency
  • Develop long-term capital improvement program projects

Westport Pump Station

Flygt Pumps and Piping (left) and Pump Controls and VFD (right)

WPCF Treatment Process Information

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Collection System Equipment and Technology

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