Utilizing Aerial Mapping for Wind Farm Construction As-BuiltsOctober 30, 2014 Wind Energy
“The easy projects have already been built.” You’ve heard it before, right? Today’s wind projects often present more challenges than those of the past. The search for high capacity factors, interconnection points, and most importantly, PPAs has urged many developers to pursue projects located in increasingly remote, mountainous terrain. The cost of designing and constructing projects in such areas can be dramatically higher than in relatively flat agricultural regions. Another cost that rises exponentially on mountainous terrain projects is for construction as-builts. However, it is possible for owners
to reduce the sting of rising as-built costs by utilizing a familiar and trusted technology: aerial mapping
Most projects today utilize aerial photogrammetry or LiDAR for mapping the existing terrain of the project site prior to construction. Many of these projects are located in hilly and mountainous regions of the country, where the best wind resources are often found. Unfortunately, to get to (and around) these sites, elaborate road networks and substantial earthwork cuts and fills are often required. The cost of construction increases with this nature of work, and one of the contributing factors to that cost is the collection of as-built data.
Some of these difficult mountain projects require contractors to move millions of yards of material to construct roads and turbines. Once completed, as-built topographic surveys are generally required to ensure the pay quantities are correct and the project roads and slopes are built per plan. Conducting as-built surveys using traditional field surveying methods of cross-sectioning many miles of roads with large, steep slopes requires significant time, can present an unsafe workplace for surveyors, and often costs many times more than collecting the data with another aerial flight. Flying the project area again after construction, re-collecting 2-foot contours using either LiDAR or photogrammetry, and utilizing this information for verifying quantities and slopes is an efficient way of saving time and a lot of money.
Grading isn’t the only activity that is reflected in as-built aerial mapping. In most cases all aspects of a project can be “as-built” from the air, including overhead transmission line routes, collection line routes, and ground disturbance areas.
Consider that digital terrain models generated from these aerial photogrammetry and LiDAR methods are trusted as a base for the original ground surface. Why wouldn’t the same technology also be trusted to generate the final “as-built” terrain for comparison as well? The answer is “It should and it is.” Be the next to re-discover and realize the cost-saving benefits of aerial mapping as an established and proven technology for generating as-built data and put the ease back into your project.