Minnesota city commissions composting system

Creekside Soils, a municipal composting facility run by the city of Hutchinson, Minnesota, has commissioned a covered aerated static pile (CASP) composting facility designed by Green Mountain Technologies (GMT) designed to increase its food waste diversion program’s capacity and processing efficiency.

Hutchinson has operated a citywide curbside source-separated organics materials (SSOM) diversion program since 2001, making it one of the oldest SSOM diversion programs in Minnesota. Creekside also composts yard waste in turned windrows and produces landscape mulches, producing bagged soil and mulch products that are sold over a 14-state area. 

Since 2001, more than 4,000 single-family households in the city have been able to dispose of food waste and yard waste in year-round weekly curbside collections. Compostables are delivered to Creekside for processing in the recently constructed six-zone below-grade CASP composting system designed and commissioned by GMT, Bainbridge Island, Washington. The CASP system at Creekside has an annual capacity of up to 1,500 tons, and each zone has an individual blower that is automatically controlled by GMT’s WebMACs control system, using a data probe inserted into each pile.

Photo courtesy of Green Mountain Technologies

The city’s composting process previously used a 16-container in-vessel system. The main goal for the new CASP composting system was to update the 24-year-old in-vessel system, also provided by GMT, which needed refurbishment. The company’s CASP composting system was selected after a competitive request for proposals process, GMT says. 

“The main goal for the new CASP composting system was simply to update a now antiquated in-vessel system we started with 20-plus years ago,” says Andy Kosek, general manager of Creekside Soils. “The in-vessel system was effective, but the vessels, the air system and the control software were starting to show their age and wear. When exploring options for a new system, cost and operational efficiency were the two main focal points; the GMT CASP system checked all the boxes.

“From the initial design to system component delivery and ultimately system commissioning, everything went as smoothly as one could expect. We were venturing into uncharted waters transitioning from an in-vessel system to an ASP system, [and] we really didn’t know how the ASP system would perform not having any previous hands-on experience with one. After a couple days of [GMT engineer and Project Manager] Peter Haun being on-site for commissioning, only very minor changes were needed to be made to the control settings; it was like the system was ‘out of the box’ ready.” 

The CASP system allows Creekside Soils to produce high-quality compost with minimal operational demands by using temperature control feedback to keep pile temperatures at the setpoint needed to maintain optimal composting conditions at all times, GMT says. Additionally, the below-grade aeration floor installed requires minimal operational interference between batches, allowing operators to quickly load and unload batches without adjusting the equipment. The facility was designed and positioned to allow the system to be expanded to 3,000 tons per year at a later date.

Photo courtesy of Green Mountain Technologies

Kosek says he’s pleased with how the system controls are set and can hold temperature. “It honestly floors me how well it is able to maintain 'flat line' temperatures within the different regime set points," he says.

“Creekside Soil’s attention to detail and commitment to excellence were evident throughout this project,” Haun adds. “With our help, they constructed a clean, efficient and visually appealing composting system that reflects their dedication and care to their community. Creekside Soils always asked the right questions and did not let any detail go unnoticed. Their curiosity and drive to perfect their craft was truly inspiring.”