The Use of Lidar in Mapping and Assessing Bedrock Foundations-PPT Presentation

PPT Presentation

Pdf Summary

USACE geologists used a Trimble SX-10 scanning total station to document bedrock foundations during the 2022–2023 construction of Bluestone Dam’s Phase 5 stilling basin in Hinton, West Virginia. Because the foundation would be covered by concrete—and the site has complex geology and significant dam-safety risks—accurate geological records were considered essential.<br /><br />The team captured photographs, LiDAR point clouds, and survey data at roughly one-inch resolution. After coordinating with the contractor to prepare, clean, and dry each area, they scanned the exposed rock from multiple positions. The scans were processed into orthophotos and base maps with gridlines and construction boundaries. Geologists then traced geological contacts and features onto high-resolution drafting film, producing foundation maps alongside digital models and topographic products.<br /><br />In 2022, the team mapped about 35,218 square feet across 10 monoliths; in 2023, it mapped about 38,734 square feet across 12 monoliths and eight key sections. The method supported detailed records, digital surfaces, presentations, and virtual walkthroughs. The presenters reported that it improved accuracy, accelerated work, and reduced construction and project risk.<br /><br />Key lessons included the importance of high-quality, complete scans and orthophotos; scanning whole areas rather than combining small patches; keeping workers and equipment clear; maintaining consistent lighting and dry conditions; and adding survey prisms where visibility is limited. Survey paint can help identify subtle features, and overhead views are preferable, but LiDAR does not replace a geologist’s field interpretation.<br /><br />Future plans include refining specifications and workflows, testing tablets, drones, and automation, organizing digital records, and adapting the approach for other projects.

Keywords

USACE

Trimble SX-10

LiDAR

bedrock foundations

foundation mapping

Bluestone Dam

stilling basin

geological records

orthophotos

construction risk