The City has aggressive and proactive Maintenance Programs to ensure that sanitary sewer mains and connections remain clear and free flowing, have structural integrity, and groundwater and storm-water runoff infiltration and inflow are minimized.
Video inspecting underground sewer infrastructure provides benefits to the Utility by providing insightful information regarding the physical deterioration and operating condition of the main lines and helps evaluate the effectiveness of the maintenance programs and procedures.
Due to this active maintenance program, the City only encounters a reduced number of sewer sanitary main backups, on average per year. These back-ups are generally related to restrictions and blockages within the mainline cause by the accumulation of debris, which was inappropriately discharged into the sewer system.
Sanitary Sewer Maintenance Programs include:
Video Inspection is the process of running cameras through sewer lines and performing detailed inspections to identify deficiencies in the sewer system as well as providing a means to evaluate the effectiveness of various maintenance procedures. Prompt repair of damaged and defective lines results in a reduction in the number of trouble spots, infiltration and inflow, and general deterioration. Below are images of CCTV footage.
CCTV inspections are also performed on sewers lines as a result of line blockages and other sewer related problems. The CCTV inspection process is critical in the detection and location of needed repairs. With the CCTV camera, the crew can find the exact location of a lateral connection and accurately identify and locate a problem. This information is valuable in the excavation and repair process as it eliminates any "guess work" towards resolving the problem.
Video Inspection is a useful tool in locating specific sources of infiltration as well as determining the hydraulics and structural condition of the sewer system. This information is necessary for the design of sewer replacement and rehabilitation projects and maintenance levels.
All newly constructed sewer lines are CCTV inspected to map the lines, verify as-built drawings and ensure the line has no construction defects. Additionally, all pipes and manholes are pressure tested to ensure tightness and prevent future infiltration of storm water and release of sewer odours. This inspection and testing process must be completed prior to the City accepting the infrastructure from the construction contractor.
Smoke testing is used to locate specific defects (leaks) in sewer mains and laterals that contribute infiltration and inflow to the sewer system. Smoke testing involves injecting a non-toxic vapor (smoke) into the manholes and following its path of travel in the mains and laterals. Coloured dye is added to the storm drain water. Dyed water appearing in the sanitary sewer system indicates an existing connection between the sewer and storm drain system. Also, coloured dye can added to the sewer connection through an on-site fixture (toilet, sink, etc.) to help determine the approximate connection point to the City sewer system. Below are images of smoke testing.
Vactor / Flush Truck crews work daily to eliminate pipe and manhole stoppages under the regular preventative maintenance programs. This equipment is used to jet clean the sewer line with high-pressure water. The debris is then vacuumed from the manhole with the high-powered vacuum hose. The Flush Truck crews also respond to emergency incidents and blockages.
Grease cutting preventative maintenance concentrates on identified / designated problem areas. Grease is a major problem in the City and takes considerable man and equipment hours. This flushing and cutting effort maintains approximately 36,000 meters of line as part of the annual grease control program, cleaning lines where stoppages or significant problems occur, in an attempt to ensure that sanitary sewer lines remain clear. The additional cleaning of locations with chronic blockage problems is performed monthly. These blockages are typically caused by or aggravated by reoccurring grease accumulations in the sanitary sewer pipes. A program to implement a City program targeting high grease accumulation areas is currently under development. If significant grease is discovered within the service connection the City will issue a letter to the owner giving notice of the by-law infraction and request the necessary action be taken to prevent the further discharge of grease into the system.
The City cuts and removes tree roots from sewer pipes that have chronic problems. This treatment must be repeated annually or as required. One problem with cutting roots, is that it acts like a pruning, and may encourage the tree to send more roots into the system.
The City conducts the following programs on the Vacuum System: