Don't Forget Manhole Rehabilitation: Significant I&I Reduction Accomplished Through Asset Management Program Methods

Don't Forget Manhole Rehabilitation: Significant I&I Reduction Accomplished Through Asset Management Program Methods WEF Collection Systems Presentation Abstract September 2021 Johnson County Wastewater (JCW) owns and operates a collection system consisting of approximately 2,300 miles of gravity pipe, 40 miles of forcemains, and 60,000 manholes. As the JCW collection system and workforce continue to age, investments in maintenance, repair, rehabilitation, and knowledge transfer to sustain desired service levels and risk tolerances will continue to grow. Increasing investment needs, coupled with limited resources, has driven JCW to continuously improve the efficiency and effectiveness of service delivery while continuing to execute day-to-day work functions. To meet this challenge, JCW and HDR staff collaborated in the development and execution of JCW's Collection System Asset Management Program (CAMP) Implementation Plan which establishes a clear, practical, and strategic path forward. JCW has executed its asset management program through this approach which identifies, prioritizes, coordinates, and schedules continuous improvement initiatives at a manageable pace that strives to balance staff availability and continuous improvement objectives. JCW's CAMP is a comprehensive, mature asset management program that encompasses all collection system assets. The efforts completed through this program have enabled JCW to forecast maintenance, condition assessment, and renewal investment needs with a high level of confidence, justify appropriate investment levels, focus limited resources, increase operational efficiency, and facilitate knowledge transfer. The asset management principles this program is built upon, and the lessons learned during the execution of this program are applicable to utilities of all sizes. One of the major program initiatives is the Manhole Inspection and Renewal Program. This presentation will present the challenges, accomplishments, and lessons learned throughout the development and implementation of the CAMP, specifically through the lens of our manhole program. The presentation will provide a review of the manhole program development (Years 1 and 2, 2016 -2017), and provide details on the accomplishments of the program goals completed in Years 3 - 6 (2018 - 2021). The program thus far has included six phases of Tier 2 inspections (over 10,000 manholes), and three phases of rehabilitation centered on both infiltration and structural findings. Pre-rehabilitation and post-rehabilitation flow monitoring has shown the program to be successful in reducing I/I, further emphasizing the importance of not forgetting about your sanitary manhole structures. The key Manhole Program accomplishments to date include: - Assessment of historical manhole inspection and rehabilitation efforts, and development of opportunities for continued improvement. - Development of JCW specific data collection standards and best practices, which focus on collecting the right data and limiting superfluous data collection. - Development and implementation of a Tier 2 inspection process utilizing 360 videos capturing defects throughout the full sanitary structure. - Development of a rehabilitation decision model and algorithm for manholes tailored to the manholes assets present within JCW's system. This model consists of multiple decision models dependent on material, structure location characteristics, cover and frame type, and drainage area conditions tributary to the manhole. - Independent QC of the rehab decision model using over 3,000 inspection findings to refine the decision model. - Testing of JCW's standard manhole cover types to determine inflow rates for each cover type and corresponding I/I reduction strategies for cover inflow. - Targeting floodplain areas and manholes susceptible of high inflow sources within various locations in the County. - Linking decision model data and 360 videos to GIS systems across departments, supporting improved decision making by allowing easy review of rehabilitation and inspection project locations. - Integrating program results and projections with JCW's basin planning and capacity enhancement program. - Automation of these tools to help execute the program. - Scaling inspection program up to 2,500 Tier 2 inspections per year, leading to complete Tier 2 inspections of over 10,000 manholes. - Completed rehabilitation of nearly 1500 manholes. - Evolution of standard specification of rehabilitation materials consistent with industry best practices. - Initial post-rehabilitation flow monitoring efforts indicating I&I reduction levels average over 20% in program focus areas. - Continuation of historical practice of capturing Tier 1 inspection data every time a manhole is opened by JCW staff members. Attachment A: Roadmap of JCW Collection System Asset Management Program Attachment B: Example Photo Using 360 Degree Manhole Camera Attachment C: Manhole Cover Inflow Testing Attachment D: Identification of Potential Manhole Inflow Sources in Floodplain Attachment E: Manhole Rehab Logic Example (Brick Manholes)