There are approximately 138 miles of sewer main in the City of San Luis Obispo’s collection system. The age varies from the 1880s to present and made of a variety of materials. Predictive and preventive maintenance is done to extend the useful life of the main and prevent stoppages. Common problems are root intrusion, grease build-up, and grit settling into sags in the sewer main. We address these problems with a specialized truck that can clean the lines with high-pressure water and also vacuum the debris from the system.
Predictive maintenance is recurring scheduled maintenance to address known problems in our collection system. Our main goal is to prevent stoppages and overflows from occurring.
The sewer mains that have known problems have been inspected and evaluated by our CCTV inspection crew and placed on a cleaning schedule. These recurring schedules are created in our Cityworks database and can automatically generate schedules for the crew on a monthly basis. We have mobile computers on our trucks that highlight the mains on a GIS map with all the pertinent data to get the job done correctly. While cleaning, the operators do a visual inspection of what they get back in the manhole while cleaning the main. If there are substantial amounts of debris, roots or grease, the crew will vacuum the manhole and make note of the conditions. If there’s justification, they will adjust the cleaning schedule (longer or shorter) to optimize the effectiveness of the cleaning. Work orders are updated and completed in the field.
Preventive maintenance is performed the same way, but with different goals. Preventive maintenance is done on mains not currently experiencing problems. The lines without problems are cleaned about every five years. Mains are cleaned by drainage basin and work orders are generated by the crew in our Cityworks database. While cleaning the main is evaluated for problems. If amounts of debris or roots are observed, the crew will make a CCTV work order to have the main inspected and evaluated. It may be put on a predictive maintenance schedule depending on the result of the inspection.