Re-Introducing the Benefits of Terrain Mapping for Pipeline Routing and Design

Abstract

Terrain mapping is the process of the interpretation of aerial photographs, LiDAR and satellite imagery plus field based ground truthing to delineate and characterize terrain polygons with similar surficial materials, landforms and geological processes [1]. For new pipeline projects, detailed terrain mapping is usually completed at a map scale of 1:20,000 corresponding to ground accuracy, at best, of 20 m. Although typically used to support the forestry industry in planning and developing forestry operations in British Columbia, Canada [2], and despite the rapid advancements of remote sensing technology, the art and science of terrain mapping continues to be an essential. albeit somewhat forgotten, tool for new and existing pipeline projects in a variety of terrain settings. For new pipeline projects, a quality terrain mapping product has been be used to characterize ground conditions and support the estimation of design inputs for numerous aspects of pipeline routing and design [3,4]. It is the backbone of most terrain and geohazard related tasks on a pipeline project and it is useful through many stages of a project’s development [5]. At routing and feasibility stages of a project, terrain mapping can be used to efficiently identify geohazards to avoid and to allow comparison of the terrain between different corridor options. Later on at the early design stages, terrain mapping can be used to develop and maintain a geohazard inventory to support geohazard risk assessment and design through geohazards that could not be avoided [6], delineate areas of shallow groundwater where buoyancy control and construction dewatering maybe required, help estimate soil spring parameters to support pipe stress analysis, delineate areas of shallow bedrock to support construction cost estimates and planning [8], and to identify sources of sands and gravels that maybe used for pipeline construction. This paper is intended to re-introduce the ongoing benefits of terrain mapping for new pipeline projects and describe how terrain mapping can cost-effectively support a pipeline project through its lifecycle of feasibility, design, and construction. Examples of the benefits of terrain mapping for routing and design of two proposed transmission pipelines in northern BC are presented. This work will be of interest to project managers, engineers, scientists and regulators involved with routing, design, and construction of new pipelines projects.