Northwest Regional Water Reclamation Facility Expansion (FL)


In 2014, Hillsborough County, Florida, began a wastewater treatment plant consolidation program for the northwest region of the county. At that time, there were three wastewater treatment plants serving the region, however, two of them were at the end of their service lives and did not have enough area around them to expand. The County’s consolidation plan was to demolish the two aging plants and expand the Northwest Regional Water Reclamation Facility (WRF) to be the sole treatment plant for the area. The expansion would see the plant’s permitted capacity increase from 10 million gallons per day (mgd) to 30 mgd. The expansion project was awarded to a joint venture (JV) partnership between Garney and Wharton-Smith as a fixed-price design-build project. Stantec participated on the JV team, providing assessment of wetland impact areas and on site mitigation areas for ecological, physical, and hydrologic features and functions by performing topographic surveys and wetland delineation and surveys. Stantec prepared construction plans and prepared and processed applications including developing compensatory mitigation for local, state, and federal permits.


Using the design-build delivery method for this project allowed for consistent collaboration among the design-build team and the County, which resulted in a lump sum GMP that included $11 million in savings to the County due to successful value engineering efforts.

Both the County and the design-build team incorporated collaborative delivery best practices throughout the life of the project, from the RFQ/RFP stage, through design, and to the end of construction. These best practices included items such as assembling a team of key project stakeholders to develop and align the vision, goals, and risks, and develop the procurement plan along with evaluation and selection process criteria. Subsequently, the County contracted a third party to assist with developing a design criteria package (DCP) to maximize the use of performance-based requirements for the competing design-build teams, while also supporting innovation and creativity among the teams. The procurement method included a competitive two-phase process. In the second phase, the technical proposal evaluation ranking point system was structured around promoting design-build best practices with innovative concepts accounting for 20% and project team approach and technical information accounting for 40%.


The Northwest facility was expanded from 10 mgd to 30 mgd. Garney and Wharton-Smith constructed significant improvements to technologies to efficiently control odor and noise, including sodium hypochlorite chemical feed facilities, aeration, four 130-foot-diameter secondary clarifiers, two D110 Type II concrete water storage tanks, conventional media filtration, grit facilities, a headworks, concrete equalization basins, and an odor control system.

The project has been awarded the following:

  • 2020 ENR Southeast Best Projects Award in the Water / Environment category, ENR Southeast
  • 2021 DBIA Design-Build National Award of Merit in water / wastewater category
  • 2020 DBIA-FL Water / Wastewater Project of the Year Award in water /
    wastewater category

Other WCDA member involved: Core & Main (supplier of air valves and miscellaneous piping)