October 8, 2008
Composting on Maui Hits Its Stride
By Trojak, Larry
EKO Compost is processing 35,000 tons/year of green waste, along with municipal bio solids and fats, oils and grease. THE Hawaiian island of Maui - a vacation destination for more than 2.2 million people each year - has a year-round growing season that yields a massive stream of green waste from nonstop cutting, trimming and pruning. For years, the resultant trimmings were simply landfilled along with the 500 tons/day of trash. One company, however, decided to turn that tide and has been aggressively taking in green waste - 35,000 tons annually - and turning it into high-quality compost products. EKO Compost ships product throughout the island chain.
Popularity of the product created at the Missoula site quickly led to the establishment of a second location in Lewiston, Idaho, and a start-up operation in California's San Joaquin valley (which has since been sold). "Then, in 1994, Maui County had a pilot program that wasn't going as well as they would have liked, so they put out an RFP for a fullfledged operation," recalls Pawlish. "We placed our bid, were selected, and started up in July of 1995. I retired from contracting in 2001 to dedicate my time fully to EKO Compost and it's been an amazing experience."
The Maui site is at the base of a stone quarry, adjacent to both a concrete plant owned by Ameron Hawaii and the island's largest municipal landfill. "Our presence there is all part of a larger, more complex plan that starts with Ameron leasing a parcel of land from the sugarcane cane company and quarrying it until all the material has been removed," explains Rubens Fonseca, EKO Compost's Maui Plant Manager. "The county then steps in and buys that land, relieving Ameron of the lease. With a large pit already in place, Maui County has a head start on building the next phase of its landfill. As a result of this setup, Maui is one of the only islands in the chain that doesn't have an urgent landfill problem right now. It's a bit unusual, but it really works to everyone's benefit."
COCOMPOSTING WITH BIOSOLIDS, FOG
EKO Compost is under contract with Maui County to accept and manage the county's green waste. It does not do any collection. "We have a Morbark Model 1300 tub grinder to grind up the green waste that arrives here all day from both commercial and residential customers," he says. After grinding at the quarry site, material is trucked about one-quarter mile away to a 5.5-acre area that, in addition to the composting operation itself, also houses its bagging and maintenance building and storage areas.
"Our primary composting operation involves mixing the ground yard trimmings with biosolids delivered here by the county from wastewater treatment plants on the island - anywhere from two to six trucks of it per day," explains Fonseca. "We also receive FOG [fats, oil and grease] diverted from the wastewater collection stream, as well as residue recovered from a biodiesel plant, also located adjacent to our compost site. Because we are able to effectively use the green waste, FOG and biosolids, this is a win-win situation for both Maui County and EKO Compost."
Materials are mixed in a converted feedlot truck with four internal augers and a specially fitted water injection system. Even though the biosolids are 85 percent liquid, adding water to the mix is still critical to the overall static aerobic process, says Fonseca. "The combination of four or five loader buckets of ground green waste for each one of sludge, coupled with the air drawn through the piles from below, can yield a very dry mix. That mixture will stay on the pile for two to three months, so adding that water in the early stages is definitely needed."
A series of 24 fans draw air through the piles and to a biofilter. Each zone of eight fans yields one batch of what will eventually be about 2,500 cubic yards of compost. After roughly 60 days, this material is moved to a curing pile where samples are pulled and sent to a lab in Oahu to be tested for fecal coliform and heavy metal content.
"We also do daily temperature probing and logging to ensure that each batch maintains temperatures of 131[degrees]F and above for 3 consecutive days, then 121[degrees]F and above for 14 consecutive days, to pass Part 503 requirements," says Fonseca. "Material is then run through a 3/8-inch screen where the overs are reintroduced to the process and the fines are sent for final curing. Altogether, we go from the beginning to final product in about six months." EKO Compost is able to rotate through this process roughly 2.5 times each year, generating between 15,000 and 20,000 yards of material. The company owns three trommels - a Wildcat Cougar, Powerscreen and a Masterscreen.
WINDROWING YARD TRIMMINGS
In addition to the FOG/biosolids/green waste composting operation, EKO is a yard trimmings windrow composting operation. Fonseca says the effort is driven by the sheer volume of material they have, by a need to reduce fire hazards, and by the availability of space in the open-pit area. Like the cocomposting operation, this one starts with primary grinding of green waste in the company's Morbark 1300.
Green waste on an island like Maui is heavily laden with fronds from a host of different palm species, each a challenge to grinder throughputs. "To offset the effects of the high palm volume, we simply don't segregate that material from the pallets and other wood products we get," says Fonseca. "We've found that doing so keeps production levels much higher." A Scarab 18 turner was purchased to manage the windrows.
He adds that EKO generally grinds for three or four days a week at the Maui location. Unforeseen downtime at that site, on the other hand, could set the operation back two weeks. "There is a constant stream of residents, landscapers, tree services, and so on, bringing material here - it builds up extremely fast. So we need reliability in our equipment." The company replaced its original grinder with a used Morbark 1300 and has bought two more units to service a contract with Hawaii County (Big Island) to grind its green waste at two locations - the Hilo landfill and the Kona Kealakehe transfer station.
EKO Compost currently offers three grades of product to its customer base of landscapers and golf courses: an original formula compost, a topsoil/compost blend and a formula designed specifically for lawn topdressing. While those mixes represent the overwhelming majority of the product shipped to each of the three main islands - Oahu, the Big Island and Kauai - the company offers special blends as well.
"A while back we went to one of the larger golf courses on Maui with the intent of selling them compost," says Fonseca. "Instead they asked for a special sand-added blend. But, because of the type of mowers they used, they needed it free of even the smallest rocks to avoid dulling their blades. So now we create the mix they need and run it through a screener with 3/16-inch holes." Because of existing Professional Golfers Association of America (PGA) rules, that special blend can only be used as a divot mix, but Fonseca feels it is still a way to show their adaptability - and it is a nice add-on product for the PGA-sanctioned courses on the island for which they already supply compost.
EKO also has a beneficial arrangement with its site neighbor, Ameron, which acquires fields for its use from the sugarcane grower. "About a year before the land can be quarried, the sugarcane cane company stops growing its crop and we buy the now-barren topsoil from them. It's a bit rocky due to its volcanic nature-which can be tough on our screens - but it still makes an excellent additive for our compost process."
Pawlish reflects on EKO Compost's journey since the early days in Montana. "We've come a long way as a company since our roots in Missoula - today we handle about 85 percent of the green waste from the Island of Maui," he says. "And with the grinding operation on the Big Island probably adding a composting function in the near future, we have no doubt that our role in keeping waste out of the landfills and providing a needed, proven product will continue."
Located at the base of a quarry, EKO Compost processes green waste made up largely of palm fronds (left). Mixed with biosolids and FOG, the material is then composted using a series of 24 fans in aerated static piles (right).
Due to a large volume of green waste, EKO has an additional composting operation dedicated to processing yard trimmings in windrows.
Materials are mixed in a converted feedlot truck with four internal augers and a specially fitted water injection system. "Today we handle about 85 percent of the green waste from the Island of Maui," says Tom Pawlish, EKO's president.
Larry Trojak of Trojak Communications is a Minnesota-based freelance writer.
Copyright J.G. Press Inc. Sep 2008
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