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City of Redwood City Page 28 Sewer System Management Plan, March 2018 Element IV IV-3 Gravity Sewer Maintenance All sewer mains in the City are assigned a preventive maintenance schedule, which consists of performing sewer cleaning at a minimum of once every four years. The Historical Regular Line Cleaning Results are detailed in Table IV-1 below. In addition, the City assigns more frequent preventive maintenance to sewer mains susceptible to root intrusion, grease accumulation, and debris deposition with the goal of preventing sewer line blockage and overflows. More frequent preventive maintenance of a sewer main is determined by a combination of the past history of blockages, sewer cleaning crew feedback, maintenance defects identified through CCTV inspection, and location with respect to other risk factors. The City maintains a list of the sewer mains identified as requiring more frequent preventative maintenance. This list is continually being updated as additional information is collected and analyzed. A list of sewer mains identified as requiring more frequent preventative maintenance, including the frequency at which each is cleaned, is included in Appendix IV-1. The City utilizes HiperWeb asset management software to track preventive maintenance activities on pipelines with more frequent sewer cleaning. The City also uses Hiperweb software to include work order generation and tracking of the City-wide jetting program. One of the primary sources of information utilized by the City to determine the appropriate preventive maintenance schedules for sewer mains is feedback from sewer cleaning crews found daily on the following maintenance feedback forms and/or HiperWeb work orders: • Preventive Maintenance Rodding Basin Program form; • Preventive Maintenance Jetting Basin Program form; and • Sewer Lateral Data form. These forms include the following information: cleaning activity, method of cleaning, findings, and whether or not further actions are necessary. These reports provide the Utilities Field Supervisor with additional information in order to determine whether to increase or decrease preventive maintenance on a particular sewer main. The maintenance feedback forms are also utilized to identify locations where further inspection and repairs are warranted. Based on the information from these cleaning reports, the Utilities Field Supervisor may create work orders for sewer main repair or manhole construction projects. The line cleaning crew rates cleaning results based upon the City’s Standard Measure of Observed Results in Appendix IV-2. The current high frequency maintenance schedule anticipates more frequent cleaning of 2.51 miles of sewers annually totaling 201,242 linear feet or 38.11 miles of total line maintenance. Summary statistics for the high frequency lines are detailed in Table IV-2 below. The City staff will be working to develop standard procedures for the addition and removal of lines from the high frequency program prior to the next SSMP Audit. This will assure proper cleaning efficiencies and will assist with a better understanding of the requirements for high frequency maintenance activities and may lead to repair or pipe rehabilitations or more aggressive discharger enforcement for the dischargers of fats, oils and grease. 6.2.A. - Page 36