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.
A commercial compost turner does
not necessarily yield the best product. That expensive
piece of equipment now sits idle.
“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
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.
“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.”
“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
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.