Brome Composting Unit

A change in city’s zoning ordinance to allow commercial composting operations could bring GreenBox to Sun Prairie to collect residential and commercial compost for online resale. Founder Ben Stanger told the City of Sun Prairie in application materials shared with the Sun Prairie Plan Commission and Sun Prairie City Council that GreenBox would like to use a Brome composting machine to process compost for resale to customers placing orders online.

A change in the city’s composting regulations — supported by the city’s Comprehensive Plan and City Sustainability Coordinator Scott Semroc — could bring a new business to the City of Sun Prairie.

On Nov. 9, the Sun Prairie Plan Commission recommended amending the Official Zoning Ordinance by amending Section 17.16.030 Table of Land Uses and Section 17.16.110 Storage or disposal land uses to allow commercial composting.

The request — approved Nov. 16 by the Sun Prairie City Council — was made by Ben Stanger, CEO and Founder of GreenBox Compost, a business that Stanger intends to found at 325 Linnerud Drive if the city council approves the zoning ordinance to allow composting operations.

“I believe with this update to Sun Prairie’s zoning code, the city can set itself up as a leader in this very important area of sustainability, while also reaping the material benefits of cutting down on waste hauling costs, and allowing for a sustainable light industry to take root,” Stanger wrote in a letter to the Sun Prairie Plan Commission that was part of the commission packet regarding the amendments last week.

“This would allow for businesses and residents of Sun Prairie to engage meaningfully with a sustainable practice, which would not only help the local environment, but also the global effort to fight climate change,” Stanger said. “This is something that the residents of Sun Prairie have clearly asked for, as evidenced by their survey results, and which is imminently achievable, through a slight change in regulations by the city.”

The survey results Stanger referred to were reviewed by Semroc during comments in favor of the amendments to the commission on Nov. 9.

“Earlier in the year we completed a resident survey regarding sustainability,” the sustainability coordinator told the commission. “Very broadly, we surveyed about 200 residents, [and] one of the top single top policies was to improve local environmental conditions by producing compost.

“The question was specific to leaves and yard waste, but I believe it reflects compost more broadly and over 86% agreed that this was a policy we should be pursuing,” Semroc said. “It was the fourth highest ranking issue of all of the survey questions that we asked.”

Semroc told the commission that Wisconsin DNR has very clearly defined rules and regulations about commercial composting.

“They provide definitions around source separated compostable material, which is what we’re referring to with food waste being diverted from the waste stream,” Semroc added. “We have several examples from other cities — Altoona, Wisconsin has similar guidance language how they define in-vessel, the balancing environmental benefits with nuisance concerns. That’s what we’re doing here.”

GreenBox plans

Stanger wrote in a letter to the commission that GreenBox Compost plans to operate a compostable waste pickup service, which will collect primarily (at least 90% of collected compostable waste) from residences in the Madison and Sun Prairie communities, at 325 Linnerud Drive, with the remainder of the compostable waste coming from businesses (the only current commitment is a verbal one from Willy Street Co-Op for one of their locations).

“We focus on residential service due to the smaller quantity of waste per dollar of revenue, and because of the larger reach we can have initially through servicing individual consumers, as opposed to businesses of any sort,” Stanger wrote. “This will also support more manageable growth, and in a way that allows us to have constant contact and feedback with the City of Sun Prairie while we do so.”

To accomplish that, two main operations need to take place; the pickup of compostable waste from residences and businesses, and the active composting of this waste in an in-vessel composting system.

GreenBox will use a fleet of electric vans (GreenBox already owns a Chanje v8070 electric parcel van).

The in-vessel composting will take place in one of several composting systems (though likely a Brome 632). “Both of these decisions have been made in an attempt to operate as efficiently as possible, while at the same time leaving as light an environmental footprint as possible — whether that refers to emissions, odor, or sound pollution,” Stenger added.

GreenBox will make pickups around the Madison and Sun Prairie area, no more than five days a week, starting no earlier than 7:30am and ending no later than 5 p.m. Only employees will ever be on site during normal operations — there will be no public drop off option. This will limit the total amount of traffic and noise on site and in the area. The electric vans will create minimal noise, less than any normal internal combustion engine, when driving around the premises.

Stanger wrote that the composting machine emits very minimal odor and noise pollution during active composting. Upon exiting the machine, the compost is not quite finished, and needs another month of curing.

“This stage has very little smell associated with it, and what it does smells like humus, and is not attractive to pests,” Stanger wrote in describing the composting product.

Residential customers will have 5 gallon buckets, and our commercial members will have 32 gallon carts, in which they will place their waste. “On our routes, we will collect these receptacles, and leave new, clean, empty containers for their use during the next period,” Stanger wrote.

Upon arrival back at the warehouse after a completed route, the GreenBox team will dump as much of the waste as possible directly into the hopper of the system, along with the appropriate amount of carbon-rich bulking agent.

Once the hopper is full, it will begin its mixing/grinding process, after which a conveyor belt and screw-auger feeder will deposit the mixture into the composter. The Brome 632 can handle about 1880 lbs. per working day, through its continuous operation, about enough capacity for composting the waste of about 120 residential members/day. “We estimate that most members will be on a bi-weekly service schedule, meaning that this system has the capacity for 1,200 residential members,” Stanger wrote.

“This capacity will allow for enough runway as we grow to size out a new, larger system when the time comes, which the site at 325 Linnerud Drive can handle. Given this, there should not be an occasion on which compostable waste is not immediately deposited from collected receptacles into the composting system to begin active composting.”

If for some reason a receptacle’s contents cannot immediately be entered into the system, a layer of bulking agent will be added on top of compostable waste within the receptacle, and it will be stored indoors for no more than 24 hours, until it can be entered into the compost system.

After exiting the system (after about 12 days), the compostable waste will have become semi-finished compost, which needs to mature, through curing, for another month, in a breathable tote bag which can hold the about 700 lbs. of discharge of a given day, and then is replaced on a daily basis. After a month has passed, the compost will be sifted, bagged, and prepared for sale.

The compost product will be sold online, and delivered with GreenBox’s pickup team, or to retailers for resale. “There will be no onsite sale of the finished product,” Stanger added.

City support

Semroc told the commission that changing the compost sections of the city zoning ordinance could lead to more such businesses in the city.

“It provides an opportunity to create an end use product and capacity for more community wide solutions,” Semroc told the commission. “This doesn’t prevent us from offering services down the road. And finally, it just turns waste into a resource, which is one of our higher level strategic goals.”

Mayor Paul Esser sarcastically asked Semroc if he supported the zoning ordinance amendments which was clear from his recommendation. But Semroc didn’t respond in kind, instead staying serious.

“I do yes,” Semroc replied. “The in-vessel in particular, reflects new technology and it’s reasonable, in my opinion.”

During the Nov. 16 Sun Prairie City Council meeting, both District 1 Alder Steve Stocker and District 2 Alder Bob Jokisch expressed support for not only the change in the zoning regulations, but also Stanger’s business. Stocker said he hoped the composting business would succeed.

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