Calculating capacity
A contour map uses non-intersecting lines of equal
elevation to quantify the shape and elevation of
a land surface. To calculate the volume, mapping
experts take this aerial data and create an up-to-
date 3-dimensional surface model of the waste at
a landfill, which is then analyzed by engineers in
CAD software and compared with a baseline surface
model (typically the prior year’s or design grades).
Based on the changes from one surface model to the
next, the most current waste volume, or remaining
capacity, can be calculated.
“By using the topographic information for
volume estimation, operators can make accurate
calculations on the remaining site life of a landfill
area,” said Ben Peotter, an environmental engineer
with Cornerstone.
A landfill has a certain intake rate of waste (based
on historical statistics) as well as a permitted
volume limit for the amount of air space its waste
occupies. Facility operators use volumetric data
to help forecast and plan for facility expansion
years in advance. They need to factor in not only
construction time but the permitting for the
expanded area as well, a process that can take three
or more years. Good planning prevents undesirable
alternatives such as reducing waste intake, which
would also mean a reduction in profit.
“That’s why volume computations are so important
in helping landfill operators manage their cash flow
and resource allocation,” Peotter said.
Time is money
And it’s also why they want those computations
made as quickly as possible.
Zach Nienow has been the Ayres Associates
geospatial project manager on numerous landfill
projects. He said that after initial aerial acquisition,
fast turnaround on topographic mapping is critical
for landfill decision-makers.
“We’re limited to a small window of time that we
can fly landfill sites, especially in the Midwest: early
spring when the ground is snow-free but before the
trees leaf out,” Nienow said. “Landfill operational
budgets can’t be finalized until the flight is done and
the topographic data is submitted for volumetric
computations.”
Internal expertise
One factor that has helped facilitate landfill mapping
projects at Ayres Associates is Nienow’s ability to
consult internally with solid waste specialists such
as Erik Lietz, who’s been working closely with waste
management collection companies for most of his
11-year career.
“We often already have a good understanding of a
landfill site – its local coordinate system, property
Above: A section of a landfill area represented as a digital
elevation model with contour lines. This is more than just an
image. Each pixel has an elevation value. Data like this helps
landfill operators calculate landfill volumes.
TRENDS
│3