Calvert Wood Recycling sits on 121 acres in the town of La Plata, Maryland, about 20 miles south of the Washington metro area. The site is located near a cluster of state parks that rim the Potomac River, meaning there is plenty of green waste being generated by landscapers and municipalities.

Calvert’s sales have grown nearly 250 percent in the last year alone. Those sales and production results come as a result of multiple contracts won for both receiving source material and delivering finished mulch to the municipality.

“We have a contract with Charles County to handle all their leaves, grass, compost, topsoil and retention soil, which contributes quite a bit of supply and demand to our facility,” says Randy Whitsell, Calvert general manager. “We’ve earned contracts with several large commercial landscapers and we are pursuing some institutional contracts now, too.”

With a slew of major contracts to fulfill, Whitsell had no desire to get set back by equipment failures—hence the decision to upgrade Calvert’s production machinery.

out with the old

Calvert recently tripled down on a full stable of new equipment.

Randy Whitsell, general manager for Calvert, says quality and efficiency drove the decision to invest in an overhaul of machinery.

“The facility had an old tub grinder and deck screen, and the product they generated was not acceptable to us,” he says. “We also knew that operational costs were far more than they should be and we wanted to bring them into alignment with efficiency goals.”

The company decided to invest in shredding, grinding and screening equipment from Doppstadt, a division of Avon, Ohio-based Ecoverse.

“We had been researching Doppstadt for a while and were aware of how well they perform,” he says. “We attended the Ecoverse Showcase in Cleveland back in 2015 and saw their equipment options there. (Regional Ecoverse representative) Andy (Lawrence) came out and met me on-site and took us around to see the equipment perform at several locations in our area, and I fell in love with it.”

increased production

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Calvert took possession of the new equipment in late spring 2016. The three pieces of Doppstadt equipment include a DW 3060K slow-speed shredder, an AK 530 high-speed grinder and a SM 720K trommel screen.

Much of its material is processed directly in the AK grinder, which feeds the SM trommel to remove fines and stockpile a finished product. Its DW shredder is employed to process heavier material, such as stumps and tree trunks, providing a primary reduction before feeding the AK grinder.

Right away, Whitsell says he saw an improvement.

According to Whitsell, there was no way to get around sending everything through there twice before using the new equipment.

“But the AK easily delivers 50 percent output on the first pass that can be screened and sold as double-ground quality mulch. The remaining 50 percent we send back through again,” he says. “In the end, we only get about 2 to 3 percent total waste in fines, where before that could be as high as 20 percent.”

A subtler benefit that Whitsell recognized is the increase wear time on the AK hammer tips.

“The upswing design on the AK hammers gives us a very consistent 1?-inch-minus product and have only needed to be changed every three weeks or so. We were lucky to get a week out of our previous hammers in the old tub grinder.”

Whitsell also appreciates the quickness of the drum switch on the Doppstadt SM 720K trommel.

“We use the trommel to make mulch and topsoil,” he says. “It easily outpaces our old deck screener. And when we need to change sizes, two people can switch out our drum in about 15 minutes. That makes production planning so much more accommodating.”


Much of Calvert’s source material has been traditional green waste and land clearing debris. But by working with the Maryland Department of the Environment, the opportunity to begin a food waste recycling program is being explored by the company.

As with most states, the quantity of food waste being landfilled is massive, taking up valuable capacity in the landfill and generating tons of greenhouse gas emissions. Diverting this waste not only solves a big landfill problem, but the recycled product can have huge end market value.

“We’ve recognized that this is a big opportunity, but it is also a challenge,” Whitsell says. “The Maryland Department of the Environment has been very helpful and they are excited to get this going in our state. We know there is money to be made here, but we are still working through the economics of the whole process right now.”

Food waste is just another organic source, and Calvert aims to create the same outputs from food waste as it does from grass and leaves.

“This will be similar to the compost market,” says Whitsell. “Bioretention soils and amendments are what we expect to generate from the food waste. But the collection, preparation and processing are different and we need to determine our best practices so we can scale this effectively.”

Organics processing, whether it be food waste or green waste, has too many challenges to let equipment be the weakest link in the process. Calvert Wood Recycling wanted to transform their operation to maximize efficiency, quality and ultimately their overall profitability.

Doppstadt equipment from Ecoverse delivered on those expectations, Whitsell says, and he could not be more pleased with the end results.

“Our goal is to crank out as much material as we can and then go out and sell it,” Whitsell says. “We need to know that peak production capacity can be reliably maintained, and our new Doppstadt machines have done just that for us.”

The article was submitted by Doppstadt, a division of Ecoverse, based in Avon, Ohio.