Big Approach to Small Diameter Sewer Rehabilitation: Design and Construction of Small Diameter Sewer Rehabilitation Package Projects

Introduction: The San Antonio Water System (SAWS) is investing over $1.2 billion dollars in its wastewater collection system, targeting over 5,200 miles of sewer main repairs, in response to city-wide sanitary sewer overflows (SSOs) and infiltration and inflow (I&I) issues. This work is under mandate from an Environmental Protection Agency (EPA) Consent Decree and is on target to be completed by 2025. One result of this Consent Decree has been an increase in package rehabilitation projects aimed at improving the worst performing sewer main segments in 'scattershot' groupings. SAWS has identified over 200 of these package rehabilitation projects to maintain the schedule of the Consent Decree. Plummer Associates Inc. (Plummer) was selected to perform the design of five small diameter package projects, together totaling over 43,000 LF of gravity sewer mains. These projects included the rehabilitation of more than 130 small diameter (8'-21') sewer main segments by various rehabilitation methods including cured-in-place pipe (CIPP), pipe bursting, open cut replacement, abandonment, and open cut rerouting. Purpose: This presentation will focus on successful project management and lessons learned for five multi-method package rehabilitation projects from preliminary design through construction. Package rehabilitation projects present a high level of risk to design and construction schedules due to the number of unique project sites, each possessing its own set of requirements for successful design and timely rehabilitation. Early design stages included data collection, condition assessment, planning for field investigations, determining agency coordination required for each site, identifying real estate conflicts, and classifying items with the highest risk to the project schedule. Methods used for organizing, classifying, and clearly presenting the overwhelming amount of data collected during these early stages was widely successful and will be discussed in detail. Subsequent design phases emphasized the prioritization of critical path activities. Critical path sequencing for these package rehabilitation projects can often be complicated due to the number of unique project sites and it may change several times during design as additional information is gathered. Successful management of these critical path activities, as well as lessons learned and unforeseen complications, will be discussed. Finally, bidding and construction administration of these projects highlighted other lessons learned and our experiences with material delays, rapidly changing material prices, real estate complications, third-party utility coordination, and contingency quantities will be discussed. Benefits of Presentation: Attendees will learn about key items to consider in the design of package rehabilitation projects, important points for successful construction administration of such projects, and how to implement big approaches to the management of small diameter sewer repairs. Owners, design engineers, and contractors will gain insights to successfully manage future package rehabilitation projects though design and construction. Status of Completion: The five package rehabilitation projects discussed in this presentation are in various stages of completion as stated below. - SAWS BPC Central Small Diameter Package 4A: Construction completed March 2022 - SAWS BPC Central Small Diameter Package 4B: Construction is substantially complete with final completion scheduled for January 2023 - SAWS BPC Central Small Diameter Package 4C: Project is currently under construction with final completion scheduled for January 2023 - SAWS Multiple Sewershed Package 17A: Construction is substantially complete with final completion scheduled for December 2022 - SAWS Multiple Sewershed Package 17B: Project is currently under construction with final completion scheduled for November 2023 Conclusion: This presentation will highlight the project approach, challenges, and lessons learned in the management of design and construction for five small diameter (8'-21') sanitary sewer package rehabilitation projects from preliminary design through construction.