A University of Georgia
engineer, a private
engineering firm and operators of a Metro Atlanta landfill
have developed a process that
could reduce the amount of landfill space needed to meet
Georgia’s needs.

Traditional landfills are designed to keep air and
water out. The new process
involves putting them in.

The old way

“Normally, organic waste is piled up, the
microorganisms begin to work and in the
process, they deplete the oxygen,” said Matt
Smith, an agricultural engineer with the UGA College
of Agricultural and Environmental Sciences.

“The waste degrades slowly,” Smith said. “And
unfortunately, methane gas
is produced.”

Landfill operators must collect the gas and either burn
it off or compress it for use
as an alternative fuel.

“Modern landfills are also lined to keep the leachate
water from getting into
groundwater,” Smith said. “This water has to be treated
before it’s sent to the
local water treatment plant.”

The new way saves space and
protects the environment

Handling the methane gas and leachate water are costly
processes for landfill
operators. Smith and engineers from the firm of Arcadis,
Geraghty and Miller developed a
process that uses air and water to speed up the
decomposing.

“We reinject the waste with the leachate water and
additional fresh water and pump
air into the waste,” Smith said. “The extra water and air
feed microorganisms
that work much quicker at decomposing the waste.”

Testing in
Georgia

The engineers tested the new process with their project
partners at Waste Management, a
national firm that operates waste treatment facilities
nationwide.

Using a 2.5-acre, 30-foot-deep waste site at the Live
Oak Landfill in DeKalb County,
Ga., the team proved the new process works.

“The waste settles much, much quicker. In the long run,
that results in more space
for landfill operators,” Smith said. “Just 12 weeks into
our first test, we
recorded 6-percent settlement.”

The new process also produces less methane. The methane
levels on the pilot site were
up to 90 percent lower than those in traditional
landfills.

“Our main 207-acre site takes in more than 5,000 tons
of solid waste each
day,” said Hughe Brown, special projects manager at the
Live Oak Landfill.
“Landfills typically have a life of 20-30 years, depending
on the volume of waste in
the area.”

Good, but pricey to
start

The process expands the life of the landfill. But the
startup cost is high.

“It cost Live Oak Landfill $2 million to test the
process. So it’s quite an
investment,” Smith said. “But the result is a much more
environmentally friendly
landfill than we traditionally see.”

Other benefits include easier
recycling

More landfill space isn’t the only benefit. The process
results in stable organic
material that can be sorted and sold or given to recycling
companies.

“What’s left are plastics, wood, cement, glass and
other stable materials,”
Smith said. “Once you’ve mined and separated the remaining
materials, you can market
them.”

Some of these materials might be sold. Others are given
away. Either case makes more
landfill space available for reuse.

Stages increase landfill
life



S. Omahen, UGA
CAES

By
using the new process, then mining the remaining materials,
a landfill could recover 75
percent to 90 percent of its space, Smith said.

“The key is to use the process in stages throughout the
landfill,” he said.
“You fill in one area while you’re decomposing another. In
the end, you’ve increased
the life of the landfill. And you’ve created a much more
stable landfill in the
process.”