40-Year Old RCP: What to do


40-Year Old Reinforced Concrete Pipe: What to do?

Authors:

Swirvine Nyirenda, City of Aurora, Aurora, Colorado
Andrea Long, City of Aurora, Aurora, Colorado
Steve Simon, City of Aurora, Aurora, Colorado

Abstract: The City of Aurora Colorado has over 1,000 miles of sanitary sewer pipelines ranging in size from 6 to 48-inches. Gravity sewers measuring less than 21-inches in diameter are inspected by Aurora Water Operations staff using Closed Circuit Television (CCTV) and Pipeline Assessment Certification Program (PACP) inspection coding. Relying on these tools and a scheduled cleaning interval of about 10 years, the water department has developed a decision logic to prioritize the rehabilitation of these lines. However, developing a decision logic for the rehabilitation of reinforced concrete pipe (RCP) interceptors greater than 21-inches in diameter with significant flows and no parallel sanitary system has presented a greater challenge because of bypass pumping requirements that, in many circumstances, are cost prohibitive. This dilemma presented the city with the following options: 1. Install a bypass pumping system to facilitate pipeline inspection, implement the decision logic, design a project, and reinstall the bypass system for rehabilitation; or 2. Formulate the rehabilitation decision logic based solely on pipeline attributes, then develop a cured-in- place (CIPP) project to include bypass pumping and an allowance for point repairs To resolve the problem, Aurora Water reviewed various multi-sensor platforms to develop an overall strategic plan for evaluating assets in this category. This paper will discuss a series of projects Aurora has undertaken to formulate the following asset management strategy for large diameter RCP interceptor rehabilitation. Aurora Water will repair all RCP interceptors using CIPP that meet the following criteria:

  1. RCP at least 30-inches in diameter
  2. More than 40 years old
  3. Carrying at least 5 MGD
  4. Flowing more than half full
  5. No record of previous inspection.

    Publication Date: 2018

    Presented at:
    NASTT’s 2018 No-Dig Show Palm Springs, California
    March 25-29, 2018 | Paper Number: MM-T1-03


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