UNITY PLANTATION, Maine — Even on a 48-degree morning, the piles of compost steam at Hawk Ridge Compost Facility as temperatures reach up to 167 degrees inside the heaps of rich, dark mulch.
Acres of minimountains of the products sit and cook — products coveted by landscapers, farmers and contractors for use on golf courses, athletic fields, campgrounds and parks.
“This is cleaner than dirt,” Mary Waring, Hawk Ridge’s compliance manager, said Thursday, “and is actually safer than a lot of other organic residuals on the market, such as cow manure.”
More than 52 major golf clubs in New England have greened their fairways with Hawk Ridge’s compost and mulch. Its material also enriches 58 athletic fields, including Foxcroft Academy, Nokomis Regional High School in Newport, the University of New Hampshire, Bates College in Lewiston, Pemaquid Park in Bristol and Brandeis University in Waltham, Mass.
What begins as municipal solid waste is combined with food waste, ashes, shredded paper or sawdust to become the ultimate recycled product through a very simple system of heat and air at Hawk Ridge.
But don’t let the uncomplicated composting system fool you.
This isn’t your grandparents’ poop. It also isn’t what you find in your backyard composting pile.
From when the facility opened in 1990 to today, massive technological changes have revamped the industry. Hawk Ridge began as a single cement pad and roof, and its products were feared by many who misunderstood its safety.
Hawk Ridge is now the largest biosolids composter in New England — handling 600,000 pounds of material a year. The facility is owned by New England Organics, a subsidiary of Casella Inc.
It accepts 145,000 cubic yards of material each year and ships 80,000 cubic yards of finished product under the earthlife brand name. As the longest running private compost facility in the Northeast, Hawk Ridge recently hit a milestone when it produced its one millionth cubic yard of compost.
Your town may be on its client list — Portland, Augusta, Bangor, Brunswick, Calais, Eastport, Falmouth, Houlton, Rockland and many others.
“Towns that bring their solids to us are very careful about their own systems,” Waring said. “The monitoring process actually begins there and a lot of the larger cities have their own pretreatment facilities.”
John Kelly, director of product safety, said Hawk Ridge is very selective about whom it contracts with. “It’s kind of an untold story about how clean the biosolids are once the cities treat them,” he said. “They can almost be land-applied at that point.”
The compost and mulch created at Hawk Ridge is screened and tested to standards far exceeding those of the federal Environmental Protection Agency and the Maine Department of Environmental Protection standards. In most cases, the material has less metal, dioxin, fecal coliform and salmonella than Maine’s average soil.
Here are some statistics: Maine soil has 7.4 parts per million of arsenic; Hawk Ridge compost has 2.7 ppm. Maine soil has 30 ppm of chromium, HR compost has 13 ppm.
This is how the system works: Biosolids are brought to the Unity Plantation facility — at peak operation, 40 trucks a day come in and out. The solids are mixed with bulking agents, such as sawdust or shredded paper, to a ratio of 25 percent solids, 75 percent bulkers.
The recipe is then stored in six cement tunnels. Each tunnel holds 600 cubic yards of material. The product stays in the tunnel for six days. Air is pushed through, temperature is monitored and escaping air is sucked into an air scrubber system to remove the ammonia smell. The temperature soars beyond 130 degrees Fahrenheit, high enough to kill all pathogens.
After six days, the product is then moved through a series of filters and screens. Piles are created, rotated and turned over as the compost continues to cook on 8½ acres of pavement. The whole process takes about 90 days.
The company was recently recognized as the first private compost facility in the country to obtain certification for a Biosolids Environmental Management System through a rigorous third-party audit.
“This is a very closely regulated business,” Melanie Solmos, director of sales and marketing, said. “We have a huge paperwork trail.”
“We decided years ago that to make just one product line was not enough,” Kelly said. “We have two focuses, the horticultural market and the agricultural market.”
Kelly said the company’s strength is that every batch of compost and mulch follows the same recipe. “Our product is different than our competition’s because ours is consistent.”
He said that in the early 1990s there was not a large market for the products. “At that time, a lot of this compost went to close landfills. Then we refined it and it became a high-end product.”
It certainly doesn’t hurt that horticulture is the fastest-growing segment of agriculture in New England and has surpassed food production in four of the six states.
In addition, Solmos said, cities and towns in Maine love the option of recycling their biosolids.
“To put this material in a landfill would be so wasteful,” Waring said. “This is a solution that will serve us well for the next 20 years.”