Inspections of the sanitary sewer system are a routine and essential duty for the Sewer Maintenance Division crews. Regular inspections can help troubleshoot and minimize problems with the collection system. Connections to the system and unwanted sources of inflow are identified through sewer inspections. As part of the sewer cleaning process, our crew chiefs inspect and report on any problems or deficiencies with the sanitary sewer system. Such items included in the inspection are:
1. Visual Inspections
Visual inspections are performed on the sewer system manholes at a higher frequency than internal inspections because of the relative ease of performance. This type of inspection can give a good indication as to the condition and proper functioning of the collection system and generally includes:
A. Manhole Inspection
- Frame & Cover
- Grade Adjustments
- Flow Surcharging
- Manhole Bottom Channels
- Structural Integrity
- Inflow & Infiltration into Manhole
- Other Miscellaneous Problems
B. Sewer Inspection
- Dirt & Stone Brought Back While Cleaning
- Abnormal Amount of Debris in Line
- Excessive Amounts of Grease in Line
- Blockage or Obstruction in Line
- Excessive Flow (Relative to Upstream Flows)
- Any Miscellaneous Problems
Any of the above items would result in further study of the sewer and include T.V. inspection, sewer repair or manhole repair. Our crew chiefs have the authority to write up anything they deem to be a problem or potential problem to the sewer system.
2. Closed Circuit Television (CCTV) Inspection
Internal sewer line inspections are performed to gather additional information about what is taking place between manhole access points. These typically include using CCTV inspections to photograph the sewer system.
CCTV inspections are performed for a number of reasons including:
- Requested by cleaning crew because of a suspected problem.
- In connection with Inflow & Infiltration investigation work.
- Sewer rehabilitation work.
- Routine check on the effectiveness of sewer cleaning.
- Sewer inspection prior to road improvements.
- Public Improvement Permits for sewer extensions.
A CCTV inspection crew consists of a Crew Chief and two maintenance workers. The Sewer Maintenance Division has two designated CCTV inspection trucks.
3. Smoke Tests
Another form of internal inspection of the sewer system is the smoke test. Smoke testing is performed to determine the following:
- Sources of ground water entry into the collection system.
- Proof that a building or residence is connected to system.
- Location of illegal connections into the sewer system including downspouts, storm water catch basins and yard drains.
- Location of broken sewers.
- Location of buried manholes or diversion points.
Smoke testing of the sewer system has the potential to affect the occupants of buildings connected to the line being tested. Defects in the sewer system of a building, dry traps, a defective wax ring under commodes, vents terminated in an attic, or cleanout plugs missing from sewers can cause smoke to enter the building. Therefore adequate preparation and advance public awareness is necessary to avoid panic or alarm. Smoke testing letter are usually sent out to each affected resident or business when smoke testing is proposed on the sewer system. A smoke crew consists of a crew chief and three observers.
4. Dye Tests
Dye testing is a method of internal inspection similar to smoke testing and provides another means of determining connections to the sewer system. Situations where dye testing may be appropriate include:
- Locating suspected illegal connections to the sewer system at roof leaders, downspouts, catch basins and yard drains.
- Estimating velocity of flow.
- Proof that a building or residence is connected to the system.