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7 of Santa Ana Section 4: Operations and Maintenance Pro 4.2.2 Preventative Maintenance The City's sewer collection system Operations and Maintenance Program consists of critical proactive, preventive and corrective measures for the City's gravity sewer system and lift stations. The details of the City's O&M Program are summarized below with further detail and specific procedures set forth in the City's Sewer System Operations and Maintenance Manual. 4.2.2.1 Gravity Mains The City of Santa Ana cleans the majority of sewer system on an 18 month cycle, and corresponding areas that are similar. However, the City does collect field observations and data during routine maintenance activities, which factor into maintenance frequencies. This utilization and analysis of field data will allow the City to optimize maintenance activities throughout the sewer system. This process will result in more sections of gravity pipelines being cleaned less frequently than the traditional 18 month cycle. The City has identified areas of the collection system that require more frequent cleaning— known as enhanced maintenance locations (EMLs) — which are cleaned on a monthly or quarterly interval. EMLs include, but are not limited to, inverted siphons that run under flood control channels and commercial areas with a high density of food service establishments. The City executes the collection system maintenance program with two sewer cleaning trucks, each staffed with a two -man crew. The gravity mains within the City are divided into two discrete zones with one crew assigned to each zone. In general, the gravity mains are cleaned in a Northeast to Southwesterly direction, following the natural gravity flow of the sewer system. To control root growth within the sewer system, the City performs as -needed root control activities. The root control activities include the use of foaming that is approved by the U.S. Environmental Protection Agency for this use. CCTV inspections are often used to evaluate the root growth and determine the appropriate mitigation measures for each stretch of impacted sewer mainlines. Sewer maintenance activities are scheduled and tracked using the GIS-based computerized maintenance management system (CMMS). For each line segment cleaned, the maintenance crews complete a report detailing the date, time, location, and key observations during the maintenance activities. Field observations include assessment of the type (e.g., roots, FOG, debris) and quantity (e.g., light, medium, and heavy) of materials removed during the line cleaning process. These observations are analyzed and factor into determinations of maintenance frequency adjustments. Additionally, observations of "heavy" accumulation are prioritized for CCTV inspection and/or other source control actions. 4.2.2.2 Lift Station/Force Mains In addition to the crews maintaining the gravity sewer system, the City's Water Production staff supports maintenance of the two sewer lift stations and the force mains are cleaned as needed. Water Production Operators are cross -trained to assist with the maintenance of these pump systems. Maintenance activities include weekly inspections of each lift station, along with periodic equipment servicing consistent with equipment manufacturer's recommendations and industry standards/best practices. 4.2.3 Rehabilitation and Replacement A comprehensive condition assessment of the City's entire sewer system was completed in 2010. The City assigned each sewer segment a structural severity rating, consistent with industry standard National April 2020 4-3 19F-21