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The Intervale’s first foray into
capitalism began in 1988 as a small-scale community leaf-and-yard-waste
recycling operation set up to help restore depleted agricultural
lands in the floodplain of the Winooski River. Since then, it
has mushroomed into a business through which an estimated 20,000
tons of waste are transformed annually into a host of agricultural
products.
Once a breadbasket to the Abenaki Indians, the Intervale
lands had been robbed of nutrients by conventional mono-crop
agriculture from the 1950s to the 1980s. “One of our
biggest barriers was soil fertility,” says Adam Sherman,
manager of Intervale Compost Products. “So we started
out with a quarter acre of land and a 20 hp farm tractor pushing
around 10 cubic yards of leaves.”
Back in the day, Intervale Compost Products used to bribe
Burlington residents to bring in their leaves by offering
them coupons redeemable for compost in the spring.
Now, operating on a 10-acre site within the 700-acre Intervale
compound, the composting operation converts tons of trash—including
compostables from Burlington and surrounding area residents
and businesses, animal manures from local farms, and about
750,000 gallons of spoiled ice cream from Ben & Jerry’s
in nearby St. Albans—into 12,000 cubic yards of black
gold. (Tanker trucks from the famous ice-cream company spray
the milky slurry over the windrows periodically in order to
encourage microbial life.)
What started out as a recycling and soil building venture
morphed into a commodities business, says Sherman. “Now,
recycling is sort of an afterthought—but it’s
still a huge benefit.”
Such a big operation does present its challenges. The 10-acre
site that accommodates wave upon wave of 400- to 800-foot-long
windrows is just 500 feet from the river, so, even with a
significant riparian buffer, runoff and leaching are concerns.
At an early point in the learning curve it was discovered--a
little too late--that asphalt was a poor choice of material
for a compost pad.
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A commercial compost turner
does not necessarily yield the best product.
That expensive piece of equipment now sits idle.
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“Blacktop can be a cost-effective impervious surface
for storage of finished compost,” says Sherman, adding
that—even at twice the price—he’d still
recommend concrete. For processing feedstock (raw compost),
he has learned that concrete's essential. The acids and microbes
that go to work in compost make it an effective bioremediation
tool for petrochemical cleanups, Sherman says. This same activity,
he said “oxidized the carbon in the blacktop and it
became a loose-grain aggregate pad…It was a hard lesson.”
There’s also no slope to speak of at the current site.
To remedy all this, a major capital improvement project is
under way to resurface the entire site in concrete and give
it an ideal 3 percent slope. (A less expensive process in
which a mixture of lime and Portland Cement is injected into
the soil to create an impervious layer is also being explored.)
Another important lesson learned was that a commercial compost
turner does not necessarily yield the best product. That expensive
piece of equipment now sits idle (it’s on the auction
block) while a Volvo excavator does the biweekly job of turning
the windrows, one scoop at a time. The excavator, basically
a giant backhoe, ruffles rather than pulverizes the compost
and provides better passive aeration, Sherman says. “It
usually takes three or four scoops to puncture the core.”
Quality controls at Intervale Compost Products include mixing
material at a rate of 27-28:1 carbon to nitrogen (for a finished
product that’s about 15-16:1), maintaining a moisture
content of about 63 percent, and achieving a 132°F center-of-pile
temperature for a consecutive 72 hours between turns.
All this fussiness is necessary to produce a consistent,
reliable product, Sherman says.
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“There’s a difference
between composting and making salsa. You’re
not just blending it and putting it in a jar.
Composting is a complete chemical, physical
and biological process. You are changing the
very structure of the material.”
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“There’s a difference between composting and
making salsa,” says Sherman. “You’re not
just blending it and putting it in a jar. Composting is a
complete chemical, physical and biological process. You are
changing the very structure of the material.”
Besides providing low-cost, high-quality compost to Intervale
farmers, Intervale Compost Products also sells bulk compost
(delivered to area farms and residences), bagged and screened
compost though retail outlets (including, of course, Gardener’s
Supply Co.), and other bagged products such as germinating
mix and potting soil. Blended garden soil—“a blend
of Intervale Complete Compost and sandy loam”, according
to promotional literature—is a relatively new venture.
“We started importing sand because we saw there was
a really strong market for manufactured topsoil,” Sherman
says, adding that this market was largely created by excavators
pawning off poor subsoil as topsoil. Intervale’s bulk
compost sells for $32 a cubic yard; a 20-quart bag retails
for $4.95.
Sherman would like to see more customers buying in the fall,
which he says is the best—if not the most widely practiced—time
for applying soil amendments. This public education would
also help with cash flow, he says. “Seventy percent
of our business falls within a 6-week window [in spring],”
he comments.
Intervale Compost Products provides a revenue stream for
an integrated community whose goal is to have a positive influence
on the greater Burlington area. As a parallel to the Intervale’s
goal of providing 10 percent of the city’s local fresh
food (it’s more than halfway there), Intervale Compost
Products aims to recycle at least 10 percent of the community’s
waste.
In 2003, the operation took in 5,140 tons of yard and garden
waste—leaves, grass, plants, pine needles and yard trimmings—and
4, 707 tons of food scraps from Chittenden County residents
and businesses.
“It’s a significant contribution to the amount
of materials diverted in our county from landfilling, says
Chittenden County Waste Reduction Manager Nancy Plunckett.
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