Safe, Efficient, Compliant

A small but savvy team at the Kill Creek Wastewater Treatment Plant sets an example with training, energy savings and biosolids process innovation.
Safe, Efficient, Compliant
Steve Duke runs a settleometer test.

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If it’s individual initiative you’re looking for, take a gander at Gardner, Kan. There you’ll find Scott  Millholland and his crew of four keeping the Kill Creek Wastewater Treatment Plant spit-polish clean, cutting the grass, shoveling the snow, and doing 99 percent of the maintenance, while keeping the plant well within compliance and seriously safe.

And by the way, they’ve also optimized the solids handling process, saving the city at least $40,000 a year, and have held plant operations expenditures at or below the previous year’s level since 2007. “We do it all,” says Millholland, wastewater supervisor, “and we love what we do.”

Their efforts haven’t gone unnoticed. Without a permit violation in more than 10 years, the Kill Creek facility was the Kansas Water Environment Association Plant of the Year in 2004, 2005, 2007 and 2012. And in three of those years, it also won the KWEA’s Safety Award.

Nutrient removal

The Kill Creek plant was built in 2001 to serve Gardner, a city of 20,000 about 30 miles southwest of Kansas City. The city’s population has doubled every ten years since 1980. In 2001, Gardner operated just three lift stations serving a sewer network of 61 miles. Today, there are 20 lift stations and 129 miles of sewers.

The main treatment process is activated sludge, using Kruger Bio Denitro phased oxidation ditch technology. The current design capacity is 2.5 mgd. Ultimate planned capacity is 7.5 mgd, and average daily flow is about 1.7 mgd.

Four Fairbanks Nijhuis submersible pumps lift wastewater to the headworks, which consist of a Muffin Monster grinder (JWC Environmental) and step screens and a wash press provided by Huber Technologies. Grit is removed with two Mectan grit chambers and a SAM grit screw (both from John Meunier).

Wastewater then passes to the phased-flow oxidation ditch system, which removes BOD and nutrients. Treated water settles in a pair of rapid sludge removal sedimentation basins (Ovivo) and then is disinfected in a dual-channel UV light system (Aquionics).

Effluent cascades down aeration steps to Kill Creek and ultimately to the Kansas River.

A fiber-optic SCADA system (Kruger) monitors and controls all plant processes. Biological odor control keeps the plant odor-free. Odorous air passes through three chambers filled with stone-type media, and odors are stripped off using effluent water.

Biosolids are removed from sedimentation basins, thickened, aerobically digested, dewatered on a belt press (BDP Industries) and applied to area farms by Synagro.

Millholland and his staff — senior operator and lab technician Steve Duke, operators Carl Cook and Matt Solorio, and maintenance specialist Dave Birzer — also take care of the lift stations. Five have submersible pumps and the rest use vacuum primed pumps (Smith & Loveless).

Solids savings

From the time the plant was built until 2008, Gardner also operated an aging fixed-film treatment plant and a package plant. Flow then averaged just 0.9 mgd, but when the old plants were taken out of service, the flow rose to 1.7 mgd. In the process, biosolids handling costs went up 20 percent, to about $120,000 a year.

“The higher costs, plus the downturn in the economy, pushed us to examine our plant operation and look for ways to trim costs,” Millholland says. Comprehensive measures to save energy would have taken too long: “The effect would not have been felt quickly enough. Instead, we felt that fine-tuning plant operations was the most promising avenue to cutting costs.” They took several measures:

  • Increasing solids wasting time in the aerobic digestion process from 40 to 60 minutes.
  • Adjusting the change in wasting time slowly, at intervals of about two to three weeks.
  • Alternating between sludge digester basins from month to month.
  • Shutting off the air to the digesters for 24 hours and then decanting three to four feet of supernate from each side using stem pipes. As a result, about 98,000 gallons per side did not need to be processed.
  • Reducing filamentous bacteria in the aerobic digestion system by alternating basins, adjusting wasting time, and lowering drawdown.

These actions have thickened biosolids in the aerobic digestion system to between two and three percent solids before the material is sent to dewatering. Millholland estimates these changes have reduced biosolids production by 40 percent, saving about $40,000 per year.

The replacement of two old drying beds with a used belt press for dewatering has increased cake solids from 7 to 16 percent, reducing solids handling costs by another $20,000 a year. “Overall, our solids handling costs are down a total of $60,000 a year, from $120,000 to $130,000 a year previously,” says Millholland.

The Gardner team saved an additional $10,000 to $15,000 a year by reviewing chemical usage for grease control in the lift stations. They’ve also started using their vacuum trucks for cleaning the stations and see much better results. The plant laboratory became a Certified Environmental Laboratory in March 2012, and that has netted even more savings, while helping with daily process control. Hach and YSI supplied most of the lab equipment.

Savings in safety

Millholland and the Gardner crew also have saved money by operating safely. “We’ve really been proactive on safety the last five years,” Millholland says. “When we boil down our worker’s compensation and insurance costs, we see significant savings. We like to have all staff get at least 40 hours a year of outside training, and this could be in the areas of operations, maintenance or safety.” Training is provided through the Kansas Department of Health and Environment, area community colleges and local vendors.

Millholland believes the training develops better, safer and more knowledgeable employees. Overall, the city has reduced worker’s compensation insurance premiums by 46 percent since 2010. “We have also received all plus points from KERIT [Kansas Eastern Regional Insurance Trust] for the last five years for our work with the safety committee and our safety program,” Millholland says. “The efforts of all city departments resulted in a savings of over $200,000.”

The treatment plant has not had a lost-time accident since it opened. “We work together as a team,” Millholland says. “You can really see the dividends.”

The key to safe performance is communication: “We have daily safety tailgate meetings. We sit down every morning, and then at the end of the day before we go home. We discuss concerns or complaints, making sure we’re all on the same page. It’s a team effort.”

Cleanliness and neatness also count. “Our plant is super clean — one of the cleanest around,” says Millholland. “We host a lot of tours with students and scouting troops. Because we have a water tower on the property, a lot of people think we’re a water plant. Just because we’re a wastewater treatment plant doesn’t mean we have to look like one.”

A clean, safe plant that conserves energy, saves money, and consistently meets its permit — that’s a formula to make any city proud.


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