Transfer of knowledge

After a devastating fire believed to be caused by a lithium-ion battery destroyed Dem-Con Cos.’ transfer station in 2018, the Shakopee, Minnesota-based company found itself without a facility—and in an interesting position. What if the company could take everything it had learned in operating transfer stations and use that knowledge to design the ideal facility from the ground up?

“It was a very unfortunate event for our business, and it caused some setbacks as far as not being able to service our customers for a period of 18 months while we rebuilt, but it gave us an opportunity to really look at [the idea of], ‘What’s your ideal design for a transfer station?’” says Bill Keegan, president of Dem-Con, a third-generation family-owned solid waste processing company employing about 350 people. “And that’s what I believe we accomplished. We’ve seen that come to fruition.”

Keegan, who has been in the waste industry for 27 years, has a background in civil engineering with an environmental focus. Drawing on his background and incorporating everything the company had learned from operating two transfer stations, the Dem-Con team set out to design what they consider to be the “most efficient transfer station possible” for throughput and transferring multiple material streams.

When it was originally built in 2001, the transfer station in Blaine, Minnesota, was outfitted with processing equipment for construction and demolition (C&D) waste. Dem-Con eventually decommissioned the processing equipment after determining that materials recovery was better performed at its central hub, an environmental campus in Shakopee.

After it was retrofitted as a pure transfer station, the Blaine facility transferred municipal solid waste (MSW), C&D and single-stream recyclables by truck to Dem-Con processing facilities or disposal sites elsewhere in the state.

After the fire, when it came time to redesign, the team approached the project with traffic flows in mind. To do this, the facility’s design prioritized the haulers that make up its customer base. The hauling community makes money out on routes and places a high value on efficiency in those routes. To minimize time spent waiting in scale lines and waiting to tip, Dem-Con zeroed in on efficiency in facility design.

“The traffic patterns for that facility required inefficient and unsafe driving patterns, which meant driving around the building,” Keegan says. “When we looked to rebuild, we wanted to improve safety, traffic flow and throughput. Our goal was to provide a service that moved customers in and out as safely, quickly and easily as possible. They want to be back on route; they don’t make any money sitting in line.”

In addition to a desire to get haulers in and out as quickly and efficiently as possible, Dem-Con aimed to provide efficient throughput and traffic flow for transferring materials into outbound transfer trailers. The original transfer station had been equipped with overhead doors designed for haulers to back into. Materials would be grabbed inside the building and then hauled to an outdoor pit for loading.

For the new facility, Dem-Con designed indoor, subgrade top-load pits, providing efficiency and the proper angle for loading and compacting materials into transfer trailers. To maximize payloads coming out of the facility, the new design incorporates two drive-through loadout pits for transfer trailers, making it possible to load two trailers at the same time and providing a safer and more efficient traffic pattern.

The facility has two large tipping floors for unloading inbound materials, one for MSW and recycling and one for C&D. One of the drive-through loadout pits runs through the middle of the building, making it accessible from both tipping floors to provide versatility in handling materials. Mobile concrete dividing walls can be adjusted to size the various tipping floors based on incoming material volumes.

“That was really important because you may have ebbs and flows in your contracts or customers,” Keegan says. “You may have a need for more MSW tip floor space and less recycling tip floor space, or vice versa.”

Focus on fire suppression

Once the basic layout was settled, Dem-Con began to envision a transfer station that kept fire protection front of mind.

In addition to its Shakopee environmental campus and two transfer stations—one in Blaine and one at the Shakopee campus—Dem-Con operates three landfills, a single-stream material recovery facility (MRF), a C&D MRF, a shingles processing facility, a wood processing facility and two metals processing sites.

For fire suppression, most of Dem-Con’s facilities use remotely monitored, heat- activated water cannons. For the new transfer station, the team chose an automated deluge system with an infrared camera. If the system senses a fire, after a delay of one minute, it will flood the entire building with fire-suppressant foam.

“For an open transfer station like we have, with all of the waste on the floor and concrete, that deluge system we found to be a much more effective way to control and extinguish a fire,” Keegan says.

In addition to annual testing, the fire suppression system has been activated twice by larger fires, says Crystal McNally, education and marketing director for Dem-Con. Both times, the system was successful in stopping the fire from doing any damage to the building and allowing fire crews access.

A successful rebuild

Dem-Con reopened its newly designed transfer station, outfitted with Caterpillar 938 loaders with grapple buckets, in 2020. In 2023, the station processed approximately 51,300 tons of MSW, 56,500 tons of C&D waste and 3,900 tons of single-stream recycling, and loaded more than 5,000 trucks outbound to recycling facilities.

Beyond facility design to facilitate throughput, running an effective transfer station operation has required an emphasis on operations, which translates to effective personnel management, Keegan says.

“You could have a great facility, but if not managed appropriately, you’re going to have lines at your scale, right?” he says. “So, it’s really training the team and having a very efficient and well-trained staff.”

History and future

Dem-Con, founded in 1965, was a landfill company in its earliest years. More recently, the company has embraced landfill diversion with a focus on waste processing and recycling, having multiple recycling facilities at its main Shakopee campus.

Looking to the future, Dem-Con plans to continue to become a one-stop shop for haulers. Keegan sees organics as the future and is anticipating transfer facilities will have to start managing the material as a separate stream. The company is in the process of developing an anaerobic digester for food waste to produce renewable natural gas and has responded to a request for proposal to separate organics from MSW.

“It’s our goal to meet the market’s unmet needs, and we believe organics is the next logical step,” Keegan says. “We’re not a zero-waste society yet, but what we’re really striving for is to process and recycle whatever we can from the waste and provide environmentally protective disposal for everything else.”

The author is managing editor of Waste Today and can be reached at smann@gie.net.