The District’s wastewater collection system includes approximately 57 miles of gravity sewer line and 4 miles of force main, ranging in diameter from 8 to 18 inches. Over 90% of the District’s sewer lines gravity flow into the wastewater treatment plant. Piping includes a combination of PVC, older concrete, and vitrified clay pipe as found in “Old Mukilteo”.

The collection staff is also responsible for insuring that nine wastewater pump stations operate on an on-going basis. Pump stations are utilized to convey wastewater from throughout the District’s boundaries to its treatment plant through pressurized lines when gravity does not provide for flow. Seven of the District’s pump stations are operated as wet/dry well facilities, while two of the stations are operated as submersible-pump stations. Staff monitors and maintains all mechanical and electrical systems associated with the pump stations on a daily basis, through a series of local alarms and a telemetry systems.