How to Best Prepare for A Major Change in Technology

Authors:

  • Matt Van Horne, Mike McGrath, Sajana Chitrakar, Jennifer Walsh, Janice Carroll

Fairfax County’s 67-mgd Noman M. Cole Jr. Pollution Control Plant (NMCPCP) in Lorton, VA is in the process of implementing $700M in capital improvement and reinvestment projects over the next 10 years.

Project drivers for the Disinfection Improvements Project included replacing aging infrastructure, meeting future regulations, providing opportunities for future capacity increases, and schedule constraints. The County also sought to simplify the hydraulic grade line, reduce pumping, and maintain flexibility for future processes.

The complex project includes replacement of the existing chlorine disinfection process with UV disinfection, replacement of three pumping stations, construction of a third outfall through federally owned property, and significant modifications to the existing NMCPCP treatment process. Due to scheduling constraints to facilitate construction of other onsite projects, the facilities are required to be online and operational by 2020.

Through the planning stages, the County assessed the efficacy of their current disinfection approach as well as the various improvements that would be required to continue this disinfection approach. As sodium hypochlorite disinfection was assessed against other potential alternatives, primarily ultraviolet disinfection and ozone disinfection, it became clear that the decision would be focused on sodium hypochlorite and ultraviolet disinfection. The final scoring of the two options, as developed collaboratively by the various groups within the County, resulted in ultraviolet disinfection being the chosen approach for disinfection improvements at the NMCPCP.

Following selection of the equipment, a demonstration pilot was conducted to verify the manufacturer’s life cycle cost claims and establish projected spending for long-term maintenance activities. Hazen coordinated directly with the manufacturer during the demonstration pilot and design process, expediting the detailed design of the new UV structure.

The County brought the CMAR firm onboard early in the design process to collaborate with the plant staff and Hazen to identify constructability issues that resulted in cost savings for the County and minimized disruptions to plant operations and local traffic patterns.

Introduction
Wastewater utilities face many challenges when preparing for a change in treatment technology, particularly one that directly relates to discharge permit compliance. The challenges become more apparent and real when the change will come in concert with a multitude of other changes at the treatment facility. For all large capital improvement projects drivers such as schedule, budget, staff availability, and implementation of new treatment processes can shape the success of a project. Taking all of these components into account, Fairfax County undertook an evaluation of their existing disinfection process with the intent to navigate the process to maximize value to the County and to result in a long-term approach to disinfection that will meet the County’s needs into the future. This case-study will provide a summary of Fairfax County’s Disinfection Improvements Project (estimated construction cost of $70M), including insights on the preliminary engineering, legal and administration procedures required for equipment procurement, and alternative construction delivery methods.

Project Background
Fairfax County Department of Public Works (DPWES) owns and operates the 67 mgd Noman M. Cole Jr. Pollution Control Plant (NMCPCP) in Lorton, VA. The facility is in the process of implementing $700M in capital improvement and reinvestment projects over the next 10 years. One of these projects is the replacement of the chlorine disinfection process with a modern and robust Ultraviolet (UV) disinfection process. UV Disinfection was identified as the preferred disinfection method based on quantitative life-cycle analysis as well as qualitative factors such as safety and ease of operation. The complex project also includes replacement of three pumping stations, construction of a third outfall through federally owned property, and significant modifications to the existing NMCPCP treatment process. Due to scheduling constraints with other CIP projects onsite, the facilities are required to be online and operational by 2020. To meet these challenges the County implemented several “best-value” approaches for the project that will be presented in detail:

  • Multi-aspect decision making for process evaluation
  • Equipment pre-selection to facilitate design
  • Collaborative project delivery
  • The overall project was driven by the following drivers that guided the County in their assessment of the various alternatives and the development of the chosen alternative.

  • The existing disinfection facilities and infrastructure is aging and some aspects have reached or are approaching the end of their useful service life.
  • The existing means of disinfection requires complicated operations and it is labor-intensive to provide the monitoring required to ensure permit compliance.
  • With the current infrastructure, it will be difficult to fully comply with the Virginia Sewage Collection and Treatment (SCAT) regulations for disinfection at future higher flows.
  • New or rehabilitated disinfection facilities offer the opportunity to simplify the hydraulic grade line, by eliminating the pumping of half of the filter effluent to the disinfection process. This will also have the added benefit of eliminating the operation and maintenance of a large pump station.
  • Advances and technology maturity in non-sodium hypochlorite disinfection technologies warrant evaluation of alternative disinfection technologies, to determine the optimal, long-term disinfection solution for NMCPCP.
  • Process Evaluation
    For Fairfax County, the need to upgrade a treatment process of this critical importance requires a significant quantity of self-examination, input from all stakeholder groups and a robust decision making process to allow for a best value decision to be reached. These elements were key through the Basis of Design Report (BODR) and Preliminary Engineering Report (PER) phases of the project. Through the BODR, the County assessed the efficacy of their current disinfection approach (sodium hypochlorite disinfection followed by sodium bisulfite dechlorination) as well as the various improvements that would be required to continue this disinfection approach into the future. As this option was assessed against other potential alternatives, primarily ultraviolet disinfection and ozone disinfection, it became clear that the decision would be focused on sodium hypochlorite and ultraviolet disinfection. The final scoring of the two options, as developed by the County, resulted in ultraviolet disinfection being the chosen approach for disinfection at the NMCPCP.

    Equipment Pre-Selection
    UV systems have long lead times and the complex design is unique to individual manufacturers, this poses a challenge for designers when planning a larger facility that must accommodate multiple manufacturers for an open bid process. Recognizing the benefits of equipment pre-selection, the County mobilized quickly at the beginning of the design process to develop an RFP that would allow them to select a manufacturer based on system layout, manufacturer experience, O&M requirements, and UV suppliers support. Following selection of the equipment, a demonstration pilot was conducted to verify the manufacturer’s life cycle claims and price costs for long term spare parts. The design engineer coordinated directly with the manufacturer during the demonstration pilot and design process. The open the lines of communication helped to expedite the detailed design of the new UV structure.

    Collaborative Delivery
    To obtain the best value, while promoting quality construction, controlling project costs, and operating within all state and local procurement regulations the County opted to use a Construction Manager At Risk (CMAR) delivery approach rather than the traditional design-bid-build process. This alternative delivery approach allowed the County to select the Construction Manager based on qualifications and unit costs, rather than the lowest bidder. The CMAR approach is relatively new to Virginia water/wastewater utilities and DPWES worked collaboratively with the County Procurement and Material Management office to develop procedures for procurement and contract execution. The County brought the CMAR firm onboard early in the design process to collaborate with the plant staff and design engineer to identify constructability issues that resulted in cost savings for the County and minimized disruptions to plant operations and local traffic patterns.

    Conclusion
    Through a focused and deliberate approach to addressing this major required technology upgrade, Fairfax County was able to effectively manage the process to provide a best value outcome for all stakeholders. The combination of a detailed technology assessment, followed by equipment pre-selection to assist in the design process and coupled with CMAR delivery of the project has allowed Fairfax County to navigate this change deliberately and successfully for all parties involved. This paper/presentation will focus on the various approaches taken and how the lessons learned through this process can be applied to other utilities facing a major technology change.

    For more information, please contact the author at mvanhorne@hazenandsawyer.com.

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