Sewer Department

Department Overview

The Sewer Department is responsible for the operation and maintenance of the wastewater treatment plant, twelve pumps stations, and approximately 35 miles of sewer mains. Below is a list of the tasks accomplished by the Sewer Department team.

Laboratory Work:

• Collect required samples to complete lab testing
• Conduct pH testing on Influent and Effluent
• Settleable solids testing is done on the Influent and Effluent
• Settle-o-meter testing is done on the contents of the aeration tank
• Check the Dissolved Oxygen level of the aeration tank and adjust it if necessary
• Total Settleable Solids (TSS) testing is done on the Mixed Liquor, Return Activated Sludge (RAS), Sludge Holding Tank (SHT), Influent and Effluent
• Biochemical Oxygen Demand (BOD) testing is done on the Influent and Effluent on Monday, Wednesday. The tests are put into the incubator for five days and are read on Saturday and Monday.

Daily Rounds:

• Check the level of the Sludge Holding Tank to determine wasting needs
• Exercise the Return Activated Sludge pump and grab the RAS sample
• Check sludge blanket depth in the clarifier
• Rake the aeration tank discharge bar rack
• Visually review operation of all systems

Additional Seasonal Requirements:

• May 15th to September 30th the Effluent is chlorinated requiring additional testing
• Maintain a Chlorine Residual in the Effluent of 1.0mg/L or less (levels tested twice a day)
• De-chlorinate the Effluent sample used for the BOD testing
• E-Coli Testing is done 2 days a week

Sludge Dewatering:

Sludge dewatering is done to remove excess solids from the plant system on an as needed basis. The amount of solids in the system will determine how often we dewater during the week. We typically dewater twice a week for 8 hours a day. Once dewatered the sludge is hauled to a composting facility by an outside vendor.

Miscellaneous Activities:

• Empty the rag cans in the Headwork’s building as needed
• Empty the Grit Hopper in the Headwork’s building on days that the Sludge container is picked up
• Chlorine contact chambers cleaned on a quarterly basis
• Clean the splitter box and clarifiers
• Building maintenance and improvements
• Manhole ring and cover replacements
• General grounds keeping at the treatment plant and pump stations
• Snow plowing

Mission Statement

The primary goal of the Sewer Department is to protect our natural resources through the effective and efficient collection and treatment of the waste water discharged by the residential, industrial and commercial members of the Lisbon community that are connected to the sewer system.