System Maintenance

Operations & Maintenance
Sewer collection systems are constructed to provide for the health and safety of the public by safely transporting sanitary and industrial wastes to wastewater treatment facilities and away from public contact.Maintenance programs are developed to protect the public’s investment in the infrastructure and to ensure the collection system operates at maximum efficiency. The maintenance program contributes directly to the health and safety of the public and the environment.

At Metro, it is our policy to perform proactive operations and maintenance activities system wide to maximize the useful life and capacity of the sanitary sewer collection system. All aspects of Metro’s management of capacity, operations and maintenance are evaluated yearly utilizing a performance based standard.

All cleaning, maintenance, and inspection data is stored in our Management Information System (MIS). This information is also used to generate performance indicators to gauge our program progress at year end and determine the work required to keep each line segment of our system operating at a proper level of service. Past performance of each system indicates that Metro currently operates an adequate schedule. A more aggressive program will be evaluated should a decline in system performance indicate that more frequent inspection is necessary. A list is compiled prior to the beginning of each fiscal year by the Operations and Maintenance Manager of collector systems to be CCTV inspected and cleaned, as well as a list of Right of Ways to be cleared. The scheduled maintenance and cleaning activities begin with the new budget year. All operations & maintenance data is added to the MIS to record the dates the work was accomplished. Any other data significant to the operations and maintenance of the system is also recorded; information includes work orders, contract rehabilitation, or any other information that may impact its performance.

Line Cleaning

Metro continually cleans its lines to ensure their performance. Metro has three line cleaning units or vehicles to clean mainline and accessible lateral pipelines. A list of collector systems to be cleaned for the current year is generated from the MIS, which also contains data that indicates the last cleaning date, the frequency of cleaning, and the next cleaning date for each collection system.

Metro’s line cleaning crew is responsible for removing debris, clearing blockages, and cutting roots that are obstructing the collection system. As a cleaner, the machine uses water to flush the lines and manholes. Many of these line blockages are due to grease build-up that is the result of households and businesses pouring fats, oils and grease down drains. Once the lines are cleaned, the combination truck vacuum system removes the debris from the sewer system so it can be disposed of in an environmentally sound way. For more information on the proper disposal of fats, oils and grease, visit our “How can I Help” page.

Smoke Testing

Smoke testing is performed to confirm connections to the sanitary sewer system. We also use smoke testing to identify sources of storm water inflow into the sanitary sewer system.

Smoke testing involves a specially mounted blower that forces air mixed with liquid smoke into a manhole. The smoke generated is nontoxic, has no odor, and is typically foggy white in color. The smoke is forced by the blower into the sanitary sewer pipes and seeks the path of least resistance. Typically the vent stacks of the homes or businesses connected to the sewer pipe being tested will release the smoke into the atmosphere.

The fire department serving the area is notified when we are smoke testing. The smoke from the sanitary sewer system will be contained in the plumbing of the structure when it is installed properly and is being used. Occasionally smoke enters the attic of the structure if the vents are not connected properly. Also, the p-trap in sinks and bathtubs may not have water in them if they have been used on a daily basis. The water in the p-trap provides a barrier that prohibits sewer gases from entering the structure from the sanitary sewer system. Therefore, smoke enters the structure as well when p-traps are dry. If smoke enters your home or building, please tell the Metro representative performing the test or call the office at 864.277.4442.

Sanitary Sewer Overflow

A Sanitary Sewer Overflow (SSO) is any spill of wastewater into the soil or stream from a manhole or pump station. Metro reports all SSO’s to SCDHEC even though they do not require reporting of SSOs less than 500 gallons. If you see or suspect an SSO, please call Metro at 864-277-4442, available 24 hours a day.


MetroConnects recently adopted new technology, the SL-Rat, to help guide regularly scheduled maintenance.  The SL-RAT is a device that uses acoustic technology to detect the presence of obstructions or debris in sewer mains.  It is highly portable, and a two man crew can easily assess a typical sewer segment in five minutes or less.  Thousands of feet of sewer can be evaluated in an 8-hour work day.  In FY 2015/2016 MetroConnects’ use of the SL-RAT, as part of operations and maintenance activities, resulted in a reduction in the time required to inspect the entire collection system, allowing a focus on cleaning and CCTV work in the areas that needed it most.


On a daily basis, the inflow and infiltration (I & I) crew uses a closed circuit television camera (CCTV) to view and record defects and maintenance problems from a television monitor inside the TV van. Metro has three CCTV units or vehicles to inspect mainline and lateral pipelines. A list of collector systems to be CCTV inspected is generated from the MIS. With information obtained from the CCTV, maintenance, repair and replacement schedules are established. For more information on I & I, visit our “How can I Help” page.

Root Control
Root control or root poisoning is a maintenance activity necessary for selected pipelines in order to maintain an acceptable level of service from an otherwise good pipeline or as a transitional measure for proper operation of a pipeline scheduled for future rehabilitation. Metro maintains a list of these line segments and performs root poisoning at scheduled intervals.

A schedule has been determined for each line segment on the list based on its condition. The work is accomplished by a contractor approved by Renewable Water Resources (ReWa) at an application rate that will not upset wastewater treatment plant operations.

Right-Of-Way Maintenance

It is Metro’s goal to keep all off road Right-Of-Way’s (R.O.W.) clear and accessible for daily and emergency operation and maintenance of our pipelines. A list of R.O.W.’s to be cleared for a current year is generated from the MIS.

R.O.W. maintenance activities include the use of outside contractors to provide chemical treatment, to control broad leaf growth (brush and trees), and large tree removal as required. Metro provides all routine mowing and brush removal with standard tractor and bush hog, small walk behind brush cutter and various hand tools (chain saws, weed eaters, etc.).

Dye Testing
Dye testing is used to confirm connections to the sanitary sewer system. We can determine where a structure is connected to the system by running dye through the plumbing of a building.Dye can be introduced into the sewer system through a sink, bathtub, toilet or a cleanout. Water is also needed to flush the dye through the piping.

Grease Trap Inspection & Enforcement
Metro follows Renewable Water Resources (ReWa) grease control strategy. It has been developed to regulate the collection and transportation of fats, oils and grease. The intent is to provide the appropriate means of collection, transportation, and disposal.

When Metro responds to a service call or emergency call and determines it is a grease problem, a call is made to ReWa pretreatment manager. An inspection is done and violations may be subject to the enforcement provisions contained in the sewer use and pretreatment regulation including fines. Violations may also be reported to SCDHEC for further enforcement action. Additional fines maybe assessed for violations involving blockages, cleanup, or other occurrences requiring increased operations and or maintenance expenses incurred by ReWa or Metro for cleanup or blockage removal.


Metro uses a yearly emergency and maintenance contract to complete repairs on our system. Our goal is to keep service disruption to a minimum. Repairs may be identified from customer calls, emergency (after hours) calls and occasionally our sewer lines are damaged by other construction. Most often repairs are identified during proactive maintenance of our system while our crews are performing Sanitary Sewer Evaluation Surveys (SSES).