Council approved a consultant contract with Robertson Bridal (RBI) to analyze dilution credits and the feasibility of adjusting zinc and copper limits in the city’s wastewater treatment plant NPDES discharge permit.

City wastewater staff described a problem: after correcting inflow and infiltration in the collection system, the plant’s lower flows and the permit’s conservative dilution assumptions make meeting the numeric zinc limits difficult. Staff said they are pursuing a two‑pronged strategy: technical recalculation of dilution credits and parameters (flow rates and mixing zones) with a consultant, and legislative or regulatory engagement to seek relief or reconsideration of the permit parameters. Staff reported they had discussed the matter with state Water Board staff and the city’s state senator’s office.

The city put the work out to bid; staff recommended selecting Robertson Bridal (RBI) because of RBI’s experience performing these calculations and working with municipalities and state staff. Staff characterized the initial phase of work as limited in scope (the contract's first phase was described as not to exceed $10,000), and council approved the phase by voice vote.

Public commenters asked how the plant’s original design and subsequent pipe repairs affected flows and whether contractor warranties exist for the treatment plant; staff and council discussed the history and noted that design assumptions changed as leaks and inflow‑infiltration were addressed and that contract warranties were not available as a practical remedy. The council approved the consultant engagement to pursue technical adjustments and shepherd state engagement; no immediate change to permit limits was made.