Wildcat WRP Capacity

Wildcat Hill WRP aerial shot

Objective 2: Address Wildcat Hill Water Reclamation Plant Capacity

Relevant Standards

  • Uninterrupted wastewater and reclaimed water services
  • Adequate collection, treatment, and disposal capacity for current and future customers
  • Maintain wet-weather capacity in compliance with regulatory requirements
  • Efficient and cost-effective approach to maintaining assets, data-driven decision making
  • Comply with current regulations and prepare for future regulations


In 2008, the Division upgraded the Wildcat Hill Water Reclamation Plant’s filtration systems to produce Class A+ reclaimed water. At that time, it was decided not to add additional digester or hydraulic capacity to save costs. Digesters treat the solids in wastewater and provide the means to create Class B Sludge, which can be applied locally on City owned land. It was decided at that time not to increase the hydraulic capacity of the Wildcat Facility.


  • The treatment plant has reached its capacity with respect to processing solids.
  • The amount of water arriving at the plant has reduced over time due to various factors, including water conservation, which means the wastewater is more concentrated, changing plant optimization parameters.
  • There is no redundancy in the plant with respect to many processes, including solids processing.
  • Failure of the current digesters would force the City to send sludge to the landfill, increasing costs by approximately $240,000 per year.

Timing Concerns

The timeline for planning, designing, and constructing a new digestor is 2024, with additional flow diversion to Rio de Flag WRP. Barring measures to buy more time, this process needs to start now to ensure adequate future capacity and avoid compliance issues with the Arizona Department of Environmental Quality

Specific Responses

  Champion Action Items Timing
1.      Look for options to buy time by increasing the effective           capacity of the current digesters _________________ _________________________
2.      Continuing assessing plant risks (points of failure and             time to repair the failure) and implementing mitigation             measures to increase reliability      
3.     Perform a cost/benefit analysis on providing                              redundancy in filtration or solids processing      
4.      Review conservation goals, projected growth, and                   future reclaimed water demands to develop the                         optimum plant parameters and timing for plant                         upgrades      

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