2017-2021 Job Order Master Agreement: Wastewater Conveyance System and Related Facilities Maintenance, Repair, Rehabilitation & Construction Services

Project Owner: Pima County Regional Wastewater Reclamation Department (RWRD)
Delivery Method: Job Order Contracting
Construction Dates: 07/17 to 07/21

The Pima County Wastewater Conveyance System JOC project involves the repair/upgrade of existing facilities by varying methods including: remove/replace existing sewer pipe, Heat/Felt CIPP Rehabilitation, Ultraviolet Light Cured-In-Place Pipe (UV CIPP) Rehabilitation, UV CIPP point repairs, rehabilitate existing manholes, frame and cover adjustments, construct new manholes, odor control equipment installation, and booster pump station rehabilitation and new construction. Total quantities to date: 34 excavation point repairs, 410 LF of new sanitary sewer pipe, 1,036 LF of pipe removal and replacement, 56,813 LF of UV CIPP, 20 manhole adjustments, 13 manhole rehabs, 15 new manholes, 22 UV point repairs, 2,452 SY of pavement, one biofilter, one dosing station, and one diversion structure. We have also completed one job order that included the installation of a bar screen structure (see details below). More highlights include:

  • Skyline Country Club Estates Sewer Rehabilitation: We completed the rehabilitation of 367 LF of 6” sewer line utilizing UV CIPP. The pipe had been installed more than 60 years ago and had deteriorated due to the remote location and rainwater runoff. Access for our equipment was limited due to the location on homeowner’s association land at Skyline Country Club Estates in the foothills of the Santa Catalina Mountains. To minimize impacts to stakeholders and the natural desert landscape we hand-carried our equipment and materials uphill to the job site, rehabilitated the sewer line, and installed a new manhole within a week.

  • Valencia Road Manhole Rehabilitation: We installed 19 Predl manholes (60”) on Valencia Road. This was Pima County RWRD’s first ever use of the Predl PVC hybrid manhole system, allowing for the rehabilitation of the existing concrete manholes. The process included the excavation and removal of existing manhole sections and base, installation of the new base liner and 54” PVC riser, grouting annular space, slurry backfill, and installation of the new flattop, grade rings, and concrete collar. We also operated a 6” bypass system to ensure the existing sewer service remained uninterrupted throughout the project. This project was selected as a 2021 Public Works Project of the Year by the Arizona Chapter American Public Works Association.

ARIZONA STATE PRISON BAR SCREEN

Bar screens are commonly used in wastewater treatment facilities to remove large or non-degradable items from the influent stream. The Arizona State Prison Bar Screen is unique in that it was installed in a gravity sewer to filter debris prior to entering an interceptor. The installation of the bar screen with minimal modifications was a significant accomplishment considering 95% of the associated sewer system components were completed prior to arrival of the bar screen. Coordination between the owner, contractor, equipment manufacturer, Tucson Electric Power, and prison personnel resulted in the completion of the project on time and within budget.

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The Arizona State Prison Complex sewer system has a large amount of plastics, fibrous material, clothing, and other solids that necessitate the use of a specialty system for removing these items prior to the wastewater treatment process. This problem was addressed by designing a new solids handling rake system that can handle the unique nature of the solids produced by the prison facility. Additionally, the two gravity lines that exit the north side of the prison grounds had to be re-routed and tied together, before entering the new solids handling system, to create one consistent source. In the future this re-alignment will allow the wastewater from the sewer to be tied into a proposed future gravity line that will be routed west along the nearby Old Vail Connection Road as a part of the Old Nogales Interceptor project. The installation of a solids handling/removal system and a new gravity main allowed the owner to remove the current failing system, which included an aging lift station and a wet well that required weekly maintenance due to debris build up.

PROJECT AWARDS

2019 Public Works Project of the Year - Southern Arizona Chapter American Public Works Association