Wildcat WRP Capacity

Wildcat Hill WRP aerial shot

Objective 2: Address Wildcat Hill Water Reclamation Plant Bio Solids 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

Background

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.

Challenge/Opportunity

  • 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  June 2020

  Champion Accomplishments Next Steps
1. Look for options to buy time by increasing the effective capacity of the current digesters Engineering Manager, Water Reclamation Manager Preparing draft scope of work for 2 New Digesters to increase capacity at WCH
Prepare RSOQ for Digester Design in next 6 months. Provide to Procurement for solicitation of bid. Go to Council for Award of Design Contract.
2.  Continuing assessing plant risks (points of failure and  time to repair the failure) and implementing mitigation  measures to increase reliability Water Reclamation Manager Replaced primary weir supports and grit lines at RDF WRP Constructing bypass line at headworks to primary system in September 2020  
3.  Perform a cost/benefit analysis on providing redundancy in filtration or solids processing Engineering Manager Issued PO to consultant for Sewer flow measurement at RDF. Awaiting return of normal sewer flows in system. Currently down 1 MGD due to Covid 19.  
4.  Review conservation goals, projected growth, and future reclaimed water demands to develop the  optimum plant parameters and timing for plant upgrades Water Resource Manager Reclaimed Water Master plan in progress  

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