Phoenix commissions $1.35m review of industrial wastewater limits
City of Phoenix Water Services Department, Arizona · Meeting date: November 4, 2026 · Published: November 5, 2026
Phoenix City Council has awarded Brown and Caldwell a five-year assignment to evaluate and, where needed, revise local discharge limits protecting the city’s two major wastewater treatment plants. The study will address risks to plant operations, biosolids land application, collection infrastructure and utility staff.
Key points
- Brown and Caldwell was approved for a five-year engineering services agreement worth up to $1.35 million.
- The study will examine industrial and other non-domestic discharges to the 91st Avenue and 23rd Avenue wastewater treatment plants.
- Work includes reviewing pollutants of concern, headworks loading calculations, industrial-user loadings and the need for new or revised local limits.
- The consultant will prepare a final sealed report for submission to EPA and the Arizona Department of Environmental Quality.
- Funding will come from the Water Services Department capital improvement programme using Sub-Regional Operating Group funds.
Full report
Phoenix City Council has approved a $1.35 million local-limits study for the city’s 91st Avenue and 23rd Avenue wastewater treatment plants, commissioning Brown and Caldwell to reassess controls on industrial and non-domestic wastewater discharges.
The five-year engineering assignment is intended to develop local controls or limits for sources discharging to the plants. Brown and Caldwell will review prior assessments and historical treatment-plant upsets, interference and pass-through incidents, while identifying significant changes at the facilities.
A central task will be identifying pollutants of concern that could threaten treatment-plant operations, the quality of biosolids intended for land application, the collection system or City wastewater personnel. The consultant will determine whether additional local limits are required and develop technically valid and enforceable control methods.
The scope also calls for a review of existing maximum allowable headworks loading calculations. Brown and Caldwell will assess whether existing loadings should be recalculated or reallocated, including in light of business growth and changes in the number of dischargers and discharge volumes. It will also evaluate whether industrial-user loadings cumulatively exceed maximum allowable industrial loading.
If existing information is insufficient, the firm may develop and implement a sampling plan to update data used in the headworks analysis. The assignment includes identifying pollutants requiring further assessment and calculating loading limits for new pollutants where needed.
Brown and Caldwell was selected through a qualifications-based process, ahead of Hazen and Sawyer and Geosyntec Consultants. The consultant will prepare a draft report for City review and a final sealed report for submission to the US Environmental Protection Agency and the Arizona Department of Environmental Quality.
The 91st Avenue plant is owned by the Sub-Regional Operating Group and operated by Phoenix. The agreement will be funded through the Water Services Department capital improvement programme using Sub-Regional Operating Group funds.
This summary was generated by AI based on the source document and may contain errors.
Source: City Council Formal Meeting, City of Phoenix Water Services Department