Aerial imagery integrated with a 3-D terrain model,
along with proposed turbine locations, can provide a
perspective view of a wind farm’s future landscape.
RES also needs to have all existing infrastructure on the
land – houses, barns, roads, transmission lines – identified
through ALTA surveys. Horton said this is particularly
important for any third-party encumbrances such as
pipelines and oil or gas wells.
In addition to legal clarity of all conditions,
encroachments, and encumbrances of the wind developer’s
leased land, ALTA surveys provide base mapping for
planning, design, crossing agreements, and construction.
Ayres Associates will be refreshing the ALTA surveys
for RES periodically because the surveys have a shelf life
of about six months.
Providing a better view
From his office in Madison, Wisconsin, Andy Selk, a
geographic information system (GIS) analyst at the wind
power development company EcoEnergy, can view
imagery of a wind farm project site on his computer
screen. The area – more than a four-hour drive away – is
near the southeastern Minnesota town of Harmony. The
6-inch resolution imagery has been ortho-rectified, meaning
it can be u sed for accurately measuring distances.
It’s also highly detailed. Selk said distinguishing
ground features is extremely important in planning a wind
farm. He can zoom in and clearly make out transmission
lines and poles, houses, cars, barns – “even the cows,” he
said.
The imagery isn’t just for GIS staff. According to
Selk, electrical engineering staff and environmental
consultants also find it useful.
Although imagery exists online from the public
domain, Selk said, “you never know what you’re going to
get.” Working with Ayres Associates, EcoEnergy opted
for the first time to acquire up-to-date, project-specific
high-resolution orthoimagery. EcoEnergy also acquired
LiDAR-derived topographic data, which provides 3-D
imagery of 2-foot surface contours. (LiDAR, or light
detection and ranging, is a technology that uses light
beams emitted from an instrument on an aircraft to
collect high-accuracy ground elevation data.)
According to EcoEnergy project manager Don Miller,
the firm has used the 3-D topographic data in preliminary
substation siting and to identify sinkholes – common
formations in the area’s karstic topography. Miller
anticipates the 3-D imagery being used even more for
setting grades for roads and determining turbine locations.
Selk made clear that site visits are necessary for
verification in project planning, but said it’s unrealistic
to think that project designers can drive to the project
area daily. And as he explained, “They won’t need to
because they’ll have high-quality imagery and data at
their fingertips.”
TRENDS
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