Site C Hydroelectric Dam – Large Scale UAV Mapping/Processing Program

Project Snapshot

Project Overview

Introduction

Underhill Geomatics Ltd. (UGL) has been engaged by BC Hydro (BCH) to deliver a comprehensive, large‑scale surveying and monitoring solution for ongoing construction activities. The project’s primary objective is to accurately capture and quantify both placed and excavated materials while providing BCH with consistent, high‑quality aerial imagery to support project oversight.

To meet these requirements, Underhill conducts regular data collection on weekly, bi‑weekly, and monthly intervals. This information supports a range of operational needs, including volumetric calculations, cost estimation, site inspections, progress monitoring, and project planning.

UGL deploys a fleet of UAV drones to capture detailed aerial imagery across the project site. The collected data is processed to generate high‑resolution point clouds, 3D models, orthomosaics, and aerial panoramas. Together, these deliverables provide BCH with a robust set of tools for tracking construction progress and making informed decisions throughout the project lifecycle.

Innovative Solutions

Developed a standardized procedure to ensure consistency in deliverables across all iterations, regardless of variations in raw data types. This process includes designing a UAV target layout plan that considers factors such as terrain, the extent of the areas flown repeatedly, ground conditions, and the specific objectives of the flights. Trinity F90+ drones are used for efficiently covering large areas in a shorter timeframe, while M300 drones are preferred for their capability to operate in high-wind conditions, which are common at the area of interest. Incorporated recursive optimization during processing stage to enhance the quality and accuracy of processed deliverables.

Underhill’s Approach

Underhill deployed Transport Canada–certified advanced UAV pilots with BCH AOD approval to safely operate over critical infrastructure. A structured aerial inspection program was executed using both thermal and photogrammetric capture methods to assess ice buildup, water behavior, structural conditions, and equipment performance.

Thermal imaging was used to verify heating system operation and identify cold spots or component failures. Photogrammetric flights generated 3D models and orthomosaics to quantify ice growth and provide visual evidence for operational decision‑making. Video and 360° imagery offered additional context for understanding winter performance challenges and identifying areas requiring maintenance.

Client Benefits

• With a focus on rapid turnaround, Underhill’s well-trained pilots and advanced drones adhere to BC Hydro’s stringent safety protocols. This ensures that clients can quickly observe changes across large site areas and receive timely deliverables, such as volumes and orthophotos, allowing them to efficiently track project progress and make informed decisions.
• Measurable Improvements: Incorporating advanced drones and high-performance computing systems has significantly enhanced our ability to deliver faster, high-quality results to clients. To date, Underhill has completed over 8000 flights, processing a vast amount of data over this time. Our ability to survey stockpile volumes in just a few hours, as opposed to days, has greatly improved efficiency. Additionally, we can easily capture overview panoramas, providing comprehensive overhead views of areas of interest on request.

Technologies Used

Equipment & Data Capture

• Quantum Systems Trinity F90+
• DJI M300, DJI Phantom 4 Pro
• Photogrammetric cameras
• Thermal camera
• LiDAR units

Software

• QBase
• Agisoft Metashape
• Spexi
• Autodesk Civil 3D
• AutoCAD

Unique Capabilities

• Special Expertise: All drone pilots hold Advanced Flight Certification from Transport Canada and have completed the client-mandated training hours. Furthermore, over 500 control points have been established across the dam construction site to ensure the highest level of data accuracy.
• Advanced Features: Underhill leverages cutting-edge drone technology, including the Trinity F90+, renowned for its ability to survey extensive areas efficiently, and the M300, specifically designed to perform reliably in extreme winter conditions. Our operations consistently deliver an accuracy of approximately 3–5 cm across all surveyed areas. For high-priority projects, our skilled processing team ensures deliverables are prepared within just a few hours. To handle the large volumes of raw and processed data, Underhill has implemented secure, efficient storage solutions and robust data management practices, enabling seamless operations and collaboration across departments.