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  • Tres Ríos Selected as APWA Arizona Chapter Project of the Year

    Jul 30, 2014 | Read More News
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    Tres Rios Clarifiers

    Congratulations to RWRD for receiving the prestigious American Public Works Association (APWA), Arizona Chapter, Project of the Year award for the Tres Ríos Water Reclamation Facility (WRF). RWRD was awarded in the “Environment—More Than $75 Million” category. The Tres Ríos Capacity Expansion and Effluent Quality Upgrade was a component of the Regional Optimization Master Plan (ROMP), which addresses the regulatory requirement mandated by the Arizona Department of Environmental Quality (ADEQ) for RWRD to reduce the amount of ammonia and nitrogen in RWRD’s effluent discharges.

    The former Ina Road WRF (renamed Tres Rios before construction was completed) was built in 1977, and a 12.5 MGD expansion was completed in 2006. To meet ADEQ mandates, the facility required significant upgrades to effluent quality discharge standards. With the replacement of the 41 MGD Roger Road plant with the 32 MGD Agua Nueva WRF, capacity had to be added to the Ina Road facility. During the construction of both the upgrade and expansion, the ongoing operation of the Ina Road WRF was required. Although this presented significant challenges, the construction of both the upgrades and expansion were carefully sequenced to maintain operations. Although staff was faced with open excavations, construction equipment, contactors’ movement throughout the facility, staff reallocations, etc., regulatory compliance was maintained throughout the entire construction period.

    Tres Rios DigesterThe Tres Ríos WRF Capacity and Effluent Quality Upgrade project consisted of many overall site improvements and increase in capacity from 37.5 MGD to 50 MGD. The old High Purity Oxygen biological treatment process was replaced with the five-stage Bardenpho process, which includes biological nutrient removal. Improvements also were made to the headworks facility, solids processing and electrical systems. A new enhanced security system was installed and landscaping and office remodeling work also were part of the improvements to the old Ina Road WRF. The 12.5 MGD expansion resulted in the new east and west trains at the Tres Rios WRF.

    RWRD employees Bobby de Angelo and Jaime Rivera were the construction and project managers respectively for the Tres Ríos project. The project management team consisted of Bobby de Angelo, Jaime Rivera, CH2M Hill, Jacobs Engineering and MWH Constructors. Delivery of the project was through a Construction-Manager-at-Risk (CMAR) procurement method. In the CMAR delivery method, the contractor held the risk of ensuring the work was done at the agreed-upon price, to standard and on schedule.

    The Tres Ríos Capacity and Effluent Quality Upgrade project was the largest construction project completed in Pima County history. Through a close partnership between RWRD, Jacobs Engineering, CH2M Hill and MWH Constructors, the project team completed this complex project ahead of schedule and within budget while continuing to provide and maintain wastewater service. Design for the project began in July 2008, and construction was substantially complete in October 2013 – three months ahead of the scheduled ADEQ compliance date of January 2014. The overall budget costs were $313.9M. State-of-the-art equipment and processes were installed to produce a very high quality effluent to A+ reuse standards. This higher-quality effluent, or reclaimed water, has a number of beneficial reuse capabilities to supply irrigation systems, replenish riparian habitats and recharge the aquifer.

    Tres Rios Odor Control“RWRD is proud of producing much higher quality effluent as an important renewable water source for the community,” said John Sherlock, RWRD Deputy Director, Treatment Division.

    Looking to the future, RWRD is becoming more sustainable in its use of wastewater treatment byproducts such as biosolids and digester gas (biogas). RWRD is actively developing a public-private partnership to implement a Biogas Sales and Utilization Project. This project would convert biogas that is currently being flared at the Tres Ríos WRF into a natural gas quality commodity called “biomethane.” Biomethane is a renewable energy source and could become a revenue stream for RWRD. With approval from the Pima County Board of Supervisors, RWRD is in negotiation with a firm that can convert biogas to biomethane. The final contract and service agreement also will require approval from the Pima County Board of Supervisors.

    The biosolids produced at the Tres Rios WRF is beneficially used through an agricultural land application program, which is by far one of the most cost effective program in the nation. Meanwhile, RWRD continues to evaluate the needs and benefits of upgrading the existing biosolids stabilization process that produces a Class B biosolids to a process that would produce a Class A biosolids product. Class A biosolids require additional pathogen removal. In addition, RWRD continues to seek opportunities to reduce energy use and to recover resources from wastewater collection and treatment processes.

    Since the Tres Ríos WRF project won at the State of Arizona Chapter level, it was automatically entered into the APWA National Project of the Year competition. The Arizona Chapter awards banquet was held on Tuesday, July 29, at the Tucson El Conquistador Hotel.