On a gray day in January, workers at the City of Corvallis (Oregon) Wastewater Reclamation Plant fanned out across the facility, carrying notebooks and flashlights.

Their goal: to identify operational improvements that could yield significant energy savings and improve sustainability. This Treasure Hunt was organized by the Public Works Department through a partnership with the Energy Trust of Oregon Strategic Energy Management program, which encourages large municipal utilities to reduce energy usage.

The wastewater reclamation plant, on the east side of Corvallis along the Willamette River, is one of the largest electricity users in the city. Plant workers challenged themselves to find energy savings equivalent to 5% of the facility’s total energy usage, which equates to approximately 223,000 kWh annually — no small feat at a facility that runs 24 hours a day and treats 4 billion gallons of wastewater annually (about 11 mgd).

Thorough approach

The energy savings initiative was led by Bob Esch, James Green, Max Hildebrand and Tom Hubbard. During the Treasure Hunt, team members examined systems and procedures throughout the plant, asking tough questions and thinking outside the box whenever possible.

In one example, team member Gabe Clark identified a large 5 hp air compressor that was set to run automatically for about 70 hours each week to provide compressed air for actuating a series of control valves. These valves are used to flush out a set of four quadrants in the bottom of an anaerobic digester. Line flushing minimizes grit buildup in the digester.

A closer examination showed that this compressor could be replaced by a smaller 1.6 hp unit running fewer hours to achieve the same goal. Annual savings from this change could reach $800 with a payback time of roughly six months.

Digging deeper

Workers identified dozens of other energy saving opportunities, large and small. Some, like swapping out the air compressor, represented quick wins. Others will require more extensive work to implement, but the potential payoffs are more substantial. Some may even qualify for grants from the Energy Trust of Oregon. In all, the workers identified more than 60 potential energy-savings projects. Among them:

• Optimize reclaimed water usage. By reducing the amount of reclaimed water used, the staff can operate using just one 40 hp pump, eliminating a second identical pump.
• Optimize aeration basin blower usage. By modifying the operating strategy used for the aeration basin and by replacing air piping that had leaks, the staff is able to use one blower instead of two, saving 60 to 75 hp, depending on which blower is running.
• Optimize the grit pumping strategy. Modification of the grit pump timers enabled a reduction of up to 50% in pumping times, saving 10 hp.
• Optimize the primary sludge pumping strategy. Modification of the sludge pump timers enabled a 5% reduction in pumping time.

Other perspectives

“The goal of the program was to change the culture and optimize the systems and equipment we already have,” says Green, a plant operator. “We’re looking at things through a new filter and breaking the old ways of thinking.”

The Corvallis team members were joined by public utility employees from Albany and Salem who had gone through their own Treasure Hunts. Inviting neighboring agencies encouraged everyone to take a fresh look at long-standing practices.

City officials praised the leadership and buy-in shown by the participants. “I was really impressed by the energetic and enthusiastic teamwork I saw during the Treasure Hunt,” says Hubbard, Utilities Division manager. “Staff members were engaged and excited to make a difference, both for their co-workers and for the Corvallis community.”

This was the second energy-reduction initiative undertaken recently in Corvallis. Last year, workers at the Taylor Water Treatment Plant conducted a Treasure Hunt that identified 37 potential energy reductions. That program wrapped up with a 5.5% reduction in overall plant energy usage, representing $17,000 in annual savings.

About the author

Patrick Rollens (patrick.rollens@corvallisoregon.gov) is public information officer with the City of Corvallis, Oregon.