The Wastewater Collection and Sanitary Engineering sections within the Lincoln Wastewater System are responsible for cleaning, inspecting, and repairing the City's sanitary sewer system. Employees strive to provide the most reliable service possible to Lincoln citizens by implementing a comprehensive preventative maintenance program.
Components of the Maintenance Program
One component of the maintenance program is to provide cleaning maintenance of sanitary sewers on a scheduled basis. The City has been divided into 122 areas, which are divided among four 2-man crews, which clean and inspect these areas about every two years. The City of Lincoln has approximately 880 miles of sanitary sewers serving approximately 230,000 residents and numerous industrial/commercial locations.
Prior to the acquisition of modern high pressure cleaning equipment in the late 1970's, much of the City's sewer system had never been inspected or cleaned and the City experienced numerous complaints along with over 100 stoppages per year. A stoppage is a clogged sewer which can cause backups and odors and often results in flooded basements and property damage. The current on-going preventative maintenance program has reduced complaints and stoppage incidences to approximately 15-20 per year.
Another maintenance effort involves the removal of tree roots from sanitary sewers. Tree roots can be a real menace, damaging sewers and causing sewers to plug. Tree roots seek the moisture and nutrients offered by leaky pipe joints usually found in the older and often broken sewer pipes. Traditional root removal methods were limited to rodding with a circular toothed bit which often proved ineffective in dense root areas.
Wastewater Collection currently controls roots by applying a mild herbicide foam from within the sanitary sewer which kills the roots in a confined area, within and around, the sanitary sewer. The herbicide is effective in killing the problem roots, is not harmful to the tree, and is approved by the EPA as an acceptable root control product which does not interfere with wastewater treatment processes.
Internal T.V. Inspection
One of the critical components of the preventative maintenance program involves internal inspection of sanitary sewers using a T.V. camera. A sealed T.V. camera is mounted on a device similar to a small sled which is pulled by an electric winch through the sanitary sewer. As the T.V. camera is pulled through the sanitary sewer and viewed by inspection personnel above ground, sewer defects are recorded for future reference and repair. A computerized ranking system analyzes the defects found in many individual sewer line segments and systematically prioritizes repairs for City line repair crews.
Along with finding sewer system deficiencies and prioritizing maintenance activities, the T.V. crew is also responsible for inspecting all newly constructed sanitary sewers before they are put into service.
Sewer Line Repairs and Construction
Sanitary sewer lines and manholes found to have major structural defects through T.V. inspection are repaired by Wastewater Collection crews when possible. Our department averages 75-125 line repairs per year at various sites throughout the City.
Hundreds of sanitary sewer manholes are also repaired each year due to poor structural condition or because they are a source of extraneous ground or surface waters.
When the scope of repair or replacement exceeds the capabilities of our equipment, we target that sewer line as a capital improvement project which is funded by user fees and constructed by a private contractor. These CIP projects are reviewed and approved by the Lincoln City Council.
I/I Removal and Reduction
Infiltration/Inflow (I/I) is extraneous water that enters the sanitary sewer system through broken pipe joints, leaky manholes, illegally connected roof drains and foundation drains, or through cross-connections with storm sewers. An important on-going task for this department is to locate and remove these sources of I/I. Excessive I/I can overload the sewer system and cause basement flooding and overload the sewage treatment facilities increasing costs and reducing treatment efficiencies.
In 1995, our department purchased and installed 30 flow meters throughout the City's sanitary sewer system. These meters incorporate the latest metering technology and accurately measure the rate of sewage flow within the sanitary sewer. The flow data received from these meters is analyzed to target areas of the City where I/I is excessive. Once an area is designated as an excessive I/I area, our field crews inspect the area looking for the specific areas where extraneous water is entering the sanitary sewer system.
Sanitary Service Problems
Our department provides 24-hour service to City of Lincoln customers. Employees are on-call to respond to your service problems or questions throughout the year. If you experience sewer service problems you should call 441-7961. A field crew will investigate the nature of the problem as soon as possible.
If you have additional questions or comments regarding the Lincoln Wastewater System, the following contacts may be made at these numbers:
- For questions regarding construction and repair activities, complaints and maintenance program call: 441-7988
- For questions regarding current projects, capital improvement projects, funding, or sources of infiltration/inflow call: 441-7987