TURNING A 1.5 MGD SECONDARY TREATMENT PROCESS INTO A 3 MGD TERTIARY TREATMENT PROCESS (WITH MBRs) ON A POSTAGE STAMP SITE

Project Objective: Turn an existing 1.5 mgd secondary treatment process/plant on 1.2 acres of useable land into a 3 mgd tertiary treatment process that can produce reuse water to the highest reuse standards in the State of Arizona.Project Scope: The Randolph Park Water Reclamation Facility (WRF) in Tucson, Arizona has been in operation as a 1.5 mgd secondary treatment facility since 1975. The facility has had a shutdown period since 1995 when a golf course expansion terminated flow to the facility. With the implementation of an Inter-Governmental Agreement, as well as regulatory changes in water quality requirements, this facility needed to be reactivated, expanded and upgraded to a 3 mgd tertiary treatment, Water Reclamation Facility, with the highest possible water quality standards for reuse (Class A+) in the State of Arizona. Some major challenges included:1.2 usable acres of land (postage stamp size)Making the most out of existing tankage (Not one cubic inch is left unused!)Central location near a busy intersectionGolf course which hosts the LPGA on the west and north property lines (the 9th tee within 50 yards of the facility)Residential neighborhood south of the plant (within 100 yards)Police station being built on the east side of the plant (with police officers not supportive of an adjacent water reclamation facility)In order to provide 3 mgd of treatment capacity at the existing facility, major changes have been made to the flow through the plant, as well as the plant process. The old primary and secondary clarifiers are now anoxic basins, and the aeration basins have been modified to allow the installation of immersed membrane bioreactor equipment. In addition, the old blower room is now a permeate pump room, and the old chlorine contact basin is now a residuals storage/handling location. Every cubic inch of the existing basins was reused to facilitate this change. Additional facilities included a new blower and administration building, and disinfection accomplished by in-line UV units.Benefits and Significance: This project resulted in benefits to Pima County, as well as benefits to Tucson Water, and the adjacent golf course. Some benefits include:Inter-Governmental Agreement between Pima County and the City of Tucson for the production of high quality reuse water, and the ownership of that water.Doubled reuse production (and subsequent wastewater processing) reduced wastewater flow to a downstream facility (the downstream facility is at capacity and is in need of relief).Highest quality of reuse water in the State of Arizona made available for wetlands use and subsequent recharge to a severely depleted aquifer.Highest quality of reuse water in the State of Arizona made available for reuse in the City of Tucson's reuse system and as irrigation for an adjacent golf course.Of significance is the cooperation and Inter-Governmental Agreement between Pima County and the City of Tucson to make this project a priority, and share in the overall benefits to the community. This is a truly unique application of new technology within existing facility constraints to obtain the highest quality (Class A+) of reuse water in the State of Arizona.