“Collection systems” refers to the system of underground pipes and maintenance structures that are used to convey wastewater to a wastewater treatment facility. The use of collection systems has brought dramatic improvements to public health in major cities. Most sewers carry wastes from households and commercial establishments and are referred to as sanitary sewers
Sanitary Sewer Maintenance
The City of Fond du Lac has a maintenance and cleaning program to keep the sanitary sewer system operating efficiently and to minimize the number of calls for service. Each month staff cleans high maintenance areas. These are problem areas due to excessive grease build up, flat lines, or roots clogging the lines.
Sewer cleaning using hydraulic or mechanical methods performed on a routine basis helps to remove accumulated debris in the pipe such as sand, silt, grease, roots and rocks. If debris is allowed to accumulate, it reduces the pipe capacity and a blockage can eventually occur resulting in overflows from the system onto streets, yards, basements, and into surface waters. The City of Fond du Lac has a full time crew assigned to flushing the sanitary sewer mains.
The City of Fond du Lac uses high-pressure sewer jet trucks and sewer vacuum trucks to clean the sanitary sewer system. To clean sanitary sewers the City uses high-pressure water to propel a jet nozzle at the end of a specialized hose through the sewer pipeline, breaking through obstructions and blockages. A flushing nozzle is installed on the end of the jet truck’s hose and the hose is lowered into the downstream manhole of the sewer section being cleaned.
This method uses high-pressure water to flush out stone, sediment or other unwanted material from the sewer. As the jet hose is rewound, high-pressure water cleans the sewer walls and back flushes all the debris.
Sewer vacuum trucks are used to vacuum out sediment, sand, stone, bricks rocks or other debris cleaned out from the sewer system. The vacuum truck can be used in conjunction with the sewer jet during cleaning operations when the sewer is too deep to clam out the material by hand or when an abundance of material is brought back to the manhole.
When a downhill grade cannot be maintained, a lift station must be installed. Primary sewers are laid beneath roads, and must be laid at depths of 1.5 to 3m to avoid damages caused by traffic loads.
A lift station pumps or lifts the waste stream from low lying areas to higher lying areas, so gravity can carry the flow to the treatment plant. Some areas must be pumped because the gravity areas are not possible.
Checks are performed on each station daily and records are maintained for run time on pumps and for flow calculations. Maintenance procedures and general housekeeping are also performed at each station. Checks are done on backup generators for readiness in case of power outages. For stations without built-in generators staff has portable generators which can be set up to operate the pump station.
All of the stations are on a SCADA tracking and alarm system. Computers monitor wet well levels and pump operation. If a pump fails an alarm is sent for the operator to respond and fix the problem. The system also keeps historical data to be used for reporting purposes.
Sewer backup often occurs when storm water enters the sanitary sewer and causes an overload of water in the system. The overloaded system begins to back flow into household lines, causing sewer water to enter basements. Call the City at the time you’re having a problem so we can check the sanitary sewer system. We need to know when and where these backups occur so we can analyze the area to determine if we can reasonably reduce future occurrences. During periods of prolonged heavy rainfalls, it is common to experience slower moving drains until the system catches up.