When Jacobs took over operations of the wastewater treatment plant in Trinidad, Colorado, the team quickly found that the aeration system was significantly overpowered.

“We had two different systems where we would inject air,” says John Kipp, project manager.

One system, providing air to the digesters and a waste activated sludge tank, had two blowers (75 hp and 90 hp) that ran alternately. The other system, feeding the aeration basins, had three 150 hp blowers that ran alternately.

“The blowers supplying the aeration basins were oversized and were producing too much air that was being wasted,” Kipp says. “We did the math and figured out that if we connected the two blower lines, one blower motor would be large enough to supply air for all the facilities.”

Making the hookup

Connecting the two systems required nothing more than 200 feet of 6-inch steel blower line. A Jacobs regional maintenance crew welded the line and had it operational in about eight days. The staff analyzed power usage for the five months before the change and the five months after and found a 61,900-kWh reduction in power consumption — 38%.

“The capital cost for the city was low,” Kipp says. “The city will be able to make its investment back in two years or less. It’s a very good return.” The change also cuts down on maintenance, as two motors and blowers no longer need to run.

Sustainability award

The savings were significant enough that the Trinidad plant received the 2019 Sustainability Award from the Rocky Mountain Water Environment Association, which recognizes “system thinking, design practices, management practices and infrastructure systems that not only sustain the utility, but society as well.”

The 75 and 90 hp blowers that are now offline are still available as backups, but now all the aeration is accomplished with the three 150 hp Hoffman & Lamson, by Gardner Denver blowers with Baldor-Reliance motors, only one of which runs at any time.

Trinidad, in the high desert at 6,000 feet of elevation, lies about 200 miles south of Denver, near the New Mexico border. The treatment plant (2 mgd design, 1.2 to 1.4 mgd average) serves about 10,000 people, mainly in the city, and some septage haulers.

The treatment process consists of screening and grit removal, aeration, clarification and UV disinfection. The effluent discharges to the Purgatoire River. Biosolids are sent to a centrifuge, on-site drying beds and then a city landfill.

The Jacobs staff of six is responsible for the plant and the collections system, which includes 66 miles of gravity mains, 6 miles of force mains and seven lift stations. “We all do some cross-training and cross-working,” Kipp says.

Saving fuel

The blower project isn’t Trinidad’s only sustainability effort. In its award application, the staff cited a successful recycling program for paper, plastic, cardboard and cans, but the program has been suspended because the recycling contractor went out of business. The staff is also working on setting up a RightCycle program for disposable gloves, sponsored by Kimberly-Clark.

Meanwhile a fuel conservation program for generators, vehicles and equipment has cut fuel consumption by 15%. “We just started tracking our fuel,” Kipp says. “We reduced trips and combined trips. If we have to run to get a part, maybe we wait until we need a few parts to make a longer trip. It’s just keeping an eye on it. We also don’t like to let vehicles idle.”

Those efforts pale in comparison to the results from combining the aeration systems. The sustainability award was just for the blower project. “That’s a big cost savings that will be here forever,” Kipp says.

CH2M began operating the Trinidad plant in 2017; that company merged with Jacobs in early 2018, and the blower project began soon after. Kipp, who previously worked at a different CH2M project, came to Trinidad in early 2019, just as the project was getting underway.

“When we go in and help cities run these facilities, we always look for ways to save money, innovate and think of good ways the city can use its capital improvement budget,” Kipp says. “We figured out how much air the blowers were putting out and how much air all five tanks needed, and we saw there was a good niche to combine the two systems. The Jacobs regional maintenance team was able to do the job, and now we’re all seeing the benefits of it.”