City of Tacoma Wastewater Treatment Plant

The City of Tacoma's wastewater treatment plant relied on aging legacy control systems that had grown increasingly difficult to maintain and operate efficiently. In the Energy & Utilities sector, outdated distributed control systems create compounding risks: obsolete hardware becomes harder to source, engineers spend disproportionate time on workarounds rather than optimization, and operators lack the real-time visibility needed to make informed decisions. Without a unified, modern control platform, the plant faced growing exposure to unplanned downtime, rising energy costs, and an inability to scale operations or implement process improvements without significant custom engineering effort each time.

Tacoma partnered with Rockwell Automation to replace its legacy infrastructure with the PlantPAx Distributed Control System (DCS) — a modern, standardized platform designed specifically for process industries like water and wastewater. PlantPAx provided plantwide control standardization, enabling operators to implement process modifications without extensive re-engineering. Alongside the DCS, the city deployed Production Intelligence and FactoryTalk Historian software, which feeds real-time operational data into a centralized historian for live monitoring and historical trending. This layered architecture connected control-layer data directly to the plant's energy management team, giving them a continuous feed of energy consumption metrics. The deployment streamlined operator interfaces through customizable, standardized graphics across the facility.

The modernization delivered measurable operational and financial improvements across the plant:

• $34,000 in annual energy savings — energy data captured by the DCS is routed directly to the city's energy management team, enabling them to identify inefficiencies and act on them continuously
• Reduced engineering deployment time — standardized control architecture means modifications and expansions no longer require custom engineering from scratch
• Improved operator usability — standardized, customizable HMI graphics reduced the cognitive load on operators and improved consistency across shifts
• Faster troubleshooting — historical trending via the Historian enables maintenance teams to correlate events and diagnose issues using time-series data rather than relying on operator recall

• Standardization pays operational dividends — a unified DCS platform reduces both training time and engineering overhead when modifications are needed.
• Connect control data to business teams — routing DCS energy data to an energy management team, not just operations, unlocks savings that would otherwise go unnoticed.
• Historian software is foundational for continuous improvement — without historical trending, troubleshooting relies on institutional knowledge rather than data.
• Legacy replacement is a long-term risk mitigation play — the cost of obsolescence (downtime, custom workarounds, sourcing challenges) often exceeds modernization costs over time.
• Wastewater facilities benefit from process-industry DCS platforms — purpose-built systems like PlantPAx reduce integration complexity compared to adapting general-purpose automation tools.