Guide for Transmission Line Foundations with Least Impact to Environment

A recently completed industry study summarizes best practice guidelines for evaluating and selecting appropriate transmission line foundations with the least impact to the environment where various sensitive and difficult conditions exist. The effort is based on a review of published case studies supplemented with selected utility and consultant surveys along with the author’s personal files to gather unpublished case history information. The report details the advantages and disadvantages of traditional foundation systems (driven piles, drilled shafts, direct embedment poles, steel grillages, spread footings, and anchored structures) and alternate foundation systems (helical anchors/piles, vibratory caissons, micropiles, rock socketed anchors, and auger cast piles). Local practices, economy, available equipment, and site access generally control the selection of foundation alternative for projects in sensitive environments. The document presents a great deal of information, options, and alternatives that must be assessed to select the optimal foundation alternative in sensitive environments. Organizing this information is critical in performing a logical assessment to arrive at the best foundation alternative for a project. A rational step-by-step model is presented where information is organized and numerical values are assigned to criteria for each foundation option.