The City of Grove City conducted a comprehensive sewer system evaluation survey (SSES) of the public sanitary sewer collection system in 2012 under a directive of the Ohio EPA. This evaluation is a proactive effort to manage the cost of the sewer system through early detection of defects and strategic planning of improvements. The SSES effort involves evaluating the condition more than 162.5 miles of sanitary sewer pipe.
The SSES program uses various equipment and techniques to detect sewer pipe defects, blockages and other problems. These techniques include smoke testing, dye testing, closed circuit TV (CCTV), flow monitoring, rainfall monitoring, manhole inspection, and sewer cleaning. As problems are identified, city engineers determine if sewer lining repair or replacement is needed and schedule accordingly. These efforts are a key component of the City’s Capacity, Management, Operation, and Maintenance (CMOM) Program, the long term strategic plan for managing the sewer system.
The goal of the SSES program is to manage the cost of maintaining the sanitary sewer system in order to prevent costly repairs, prevent failures of the system and to minimize the inconvenience to residents. It is imperative that operators of sanitary sewer collection systems implement a long term plan to prevent the occurrence of disruptive problems in the sanitary sewer, regardless of cause.
Sewer Evaluation Schedule
Sewers are grouped into areas known as sewer sheds. A sewer shed is defined by the geographic area collected by local sewers and roughly follow subdivision boundaries. Each year sewer shed areas are selected for inspection, with priority given to areas that have known problems (as documented in the maintenance history or concerns from residents) or by age of construction. The focus has been placed on the older parts of Grove City, centered around the Town Center area. Beginning in the late 1990’s the City has implemented an annual evaluation program and has investigated the condition of the majority of the sewers centered around the older areas of the City. The program is now evaluating sewers in the older subdivisions centered around the downtown area.
The City uses a strategic approach that pinpoints areas of concern for detailed investigation. This approach begins with flow monitoring, which measures the flow inside a sewer that collects large area. If the sewer is not performing as predicted, the upstream area will undergo an evaluation using a process known as smoke testing, which blows smoke into the sewer system and problems are found by identifying locations where the smoke escapes the sewers. In areas where smoke is found to escape the sewer, dyed water and a CCTV camera is utilized to find defects in the pipes.
Defects are documented and repairs are scheduled according to the severity of the problems observed. Emergency issues, like blocked or broken pipes are corrected immediately. Non-emergency issues, such as cracked pipes or root intrusions, are scheduled for rehabilitation under the annual repair program. Minor issues that can be resolved through maintenance, such as small root intrusions, grease deposits, or sediment, are placed on a routine cleaning or root control schedule. Pipes that are found to be in satisfactory condition remain in the survey schedule and will be reevaluated in the future under the evaluation program.