Bridging the Gap: Bringing Data Transparency in a Citywide Wastewater System Condition Assessment Program for I/I Mitigation

Background: In 2018, the City of Temple, Texas, and the Environmental Protection Agency (EPA) agreed upon an administrative order for the purpose of compliance with the Clean Water Act (CWA) regarding sanitary sewer overflows (SSOs) from the City's sewer collection system. The City of Temple's wastewater system consists of over 2.1 million linear feet of gravity sewer mains, over 95,000 linear feet of force mains, 4,000 linear feet of pressurized siphons, twenty-eight lift stations, approximately 6,400 sanitary sewer manhole structures, and two wastewater treatment plants all divided into six sanitary sewer basins. As part of the administrative order, the City of Temple is to conduct a condition assessment of the existing sanitary sewer infrastructure and perform rehabilitation/replacement of defective infrastructure. With a system of significant size, data collection and management processes for the condition assessment become of utmost importance. The City of Temple partnered with RJN to execute the condition assessment requirements and develop a remedial program. This presentation will provide an overview of the data collection, management, analyses, and data delivery methods undertaken in this multi-year condition assessment project and how the City of Temple is utilizing the data to mitigate Infiltration/Inflow (I/I) from entering their system and reducing SSOs. Methodology: Data collection involves various field activities. Data collection began with flow monitoring of the entire system. In Spring 2019, thirty-six meters and eight rain gauges were used to collect wastewater flows and rainfall for a 74-day period for the hydraulic model calibration. Over 23,000 data points were collected through the flow monitoring. Data collection for the condition assessment includes manhole inspections, closed-circuit television (CCTV) inspections, smoke testing, and dye testing. A portable manhole scanner was the technology selected for manhole inspections as it eliminates the risks involved with man-entry inspections and provides multiple views of the entire manhole, which is useful during quality control. To date, over 3,500 manholes have been inspected and coded using the National Association of Sewer Service Companies (NASSCO) Manhole Assessment Certification Program (MACP) method. Per the administrative order, CCTV inspections are required only for the non-plastic sewer pipes. To date, over 275,000 linear feet of non-plastic sewer pipe has been inspected and coded using the NASSCO Pipeline Assessment Certification Program (PACP) method. The dual-blower method was selected for the smoke testing with GPS points collected at the defect location through an iPad and a survey form. To date, over 1,120,000 linear feet of gravity main sewer has been smoke tested, with over 2,500 defects identified. Dye testing (20 setups) was used to quantify I/I from significant defects identified during smoke testing. All the collected data is integrated into various programs to assist in the management and analysis. The flow monitoring data was used in the hydraulic model with Innovyze® InfoWorks ICM. Using the hydraulic model, an I/I analysis was performed using the collected flow monitoring and rainfall data that helped identify the I/I within each basin. RJN utilizes its proprietary software, RJN Project Management (RPM), to keep all records of the manhole inspections along with smoke and dye testing observations. This helps keep track of the progress and findings from the field investigations. Two analyses are performed, an I/I analysis and a rehabilitation analysis. For the smoke and dye testing, RPM is used to perform both the I/I and rehabilitation analysis. Because the manhole and CCTV inspections use MACP and PACP coding, the I/I and rehabilitation analyses are performed through Innovyze® InfoAsset Planner. Through this program, RJN developed rehabilitation decision trees that utilize the MACP and PACP databases to determine asset-specific rehabilitation or replacement recommendations. At the end of the first year, the data deliverable consisted of the manhole scans, CCTV videos, smoke defect photos, and MACP and PACP Access databases. This method provided the data in separate formats, some of which required a further understanding of Access databases. By the end of the second year, RJN had developed an online platform, Clarity®, that provides the data in one location in a user-friendly format and gives the City of Temple access throughout the project allowing city staff to view the progress from data collection to finalization. The City of Temple uses Clarity® to view the GPS location of service line defects and verify proper sector categorization. They also pull images and datasheets for easy uploading to their Cityworks® work order system. Using these programs, RJN and the City of Temple are using data-driven decisions in the plan development and execution of the condition assessment program. The I/I analysis results from the flow monitoring data were used to develop the multi-year condition assessment program based on the excessive I/I identified within each sanitary sewer basin. Prioritization for the condition assessment was given to the basins with the highest I/I, along with consideration of annual budgets. The I/I and rehabilitation analyses for the condition assessments of each basin provide a data-driven remedial action plan, which include operations and maintenance (O&M), rehabilitation, or replacement. In addition, asset rehabilitation prioritization for each of the inspected assets is determined based on cost-effectiveness where the estimated contributing I/I and the cost of rehabilitation are compared. These developed prioritization metrics assist the City of Temple in determining which remedial actions to complete first and which can be done in-house or have a contractor perform the repair. Conclusion: Although using multiple programs for the data collection, coding, management, and analysis, these programs facilitate tracking the collected data, evaluating the identified defects and asset conditions, determining the appropriate remedial recommendation, and presenting the data to the City of Temple. Condition assessments using these methods and programs have been completed for two sanitary sewer basins, and we are currently working on the third. Through the collaboration and data transparency with the City of Temple staff, RJN has been able to improve the data deliverable to a user-friendly format for integration with Temple's work order system. The City of Temple has addressed the high-priority rehabilitation recommendations as provided by RJN for the defects identified through smoke testing from the first year's project. The City of Temple is also working on completing the manhole and sewer line rehab, also categorized as high priority. Although not all the remedial recommendations from the first condition assessment have been addressed, Temple has realized a 50% reduction in SSOs in this first basin proving the metrics derived for the remedial prioritization successful.