Innovation Reduces Subsurface Risk for Transmission Lines

October 24, 2018

With the growing demand for reliable and affordable energy in the U.S., the design and construction of power generation facilities and transmission infrastructure is happening at a rapid pace. To keep pace with the required demand, and to remove barriers to the development of transmission, the Federal Energy Regulatory Commission (FERC) issued order 1000 in July 2011. Since the introduction of FERC Order 1000 (Competitive Transmission)an increasing number of utilities are adopting the Engineer, Procure and Construction (EPC) model. With this model, complete proposals incorporating the sum of all engineering, financing, and construction costs are submitted prior to project award. Therefore, the ability of an EPC to estimate design and construction costs with limited upfront investigative work has become necessary in order to be awarded the projects. While the above grade construction costs are readily calculated for transmission line construction, the below grade construction costs are heavily dependent on subsurface geotechnical conditions and can vary greatly depending on location. With this in mind, the importance of understanding subsurface geotechnical risk prior to submitting a proposal is more important than ever. Herein lies the problem; historically, the risk presented by geotechnical conditions have been characterized by intrusive exploration studies that take place prior to final design which can take weeks to months to accomplish. Terracon has implemented a unique solution to this problem.

Connecting Data for Utilities

Since approximately 2008, Terracon has been collecting the location information of our borings to make this information easily accessible to our geotechnical practitioners through GIS systems. With the conduct of over 15,000 geotechnical projects per year, we have amassed a large amount of proprietary subsurface information for the entire country over the last 10 years.  Additionally, we are investing in digitizing and geolocating all our historical data from across the country for the years prior to 2008 dating back to the 1950s.

Terracon is helping our EPC and utility owner clients by connecting this existing historical geotechnical data near potential project sites with a local geotechnical engineer’s knowledge of the geological conditions to render a report that predicts the expected geotechnical conditions, without the time associated with intrusive geotechnical studies. We call this report a Stage1 GeoReport. The Stage1 GeoReport not only provides a prediction of the geotechnical conditions, but also a confidence level of the conditions, and can even provide estimated foundation parameters using LPILE computer software, moment foundation analysis and design (MFAD), and other industry standards. These foundation parameters are key to estimating foundation costs which are often the largest unknown cost and risk to a transmission project. For larger projects, the Stage1 GeoReport can also help identify alternative corridors with lower geotechnical risks or foundation costs.

The Benefits of Stage1 GeoReport

“When meeting with owners, design engineering firms, and constructors I’m often told ‘what a great tool’ or ‘I’ve never heard of another firm doing this,’” said Michael Heller, energy sector leader for Terracon’s Power Generation & Transmission Services Business Sector. Michael describes a recent meeting with a transmission line developer that he helped win a recent project and in describing the Terracon predictive-approach he says, “I was told ‘every design firm we work with is aware of this approach and it’s helping them better understand their subsurface risk prior to the field exploration program which helps us be more competitive’.”

By utilizing a more complete siting data set, transmission clients are improving the way they approach transmission line routes, saving time, money, and creating routes based on more informed decisions, in addition to wining projects. Utilizing this approach, Terracon has assisted with some of the largest transmission line projects in the country and is able to apply this predictive concept to countless of other site location opportunities.

Michael Heller is an energy sector leader for Terracon’s Power Generation & Transmission Services Business Sector. Michael specializes in national account management and client development services.

Find an office location

More than 175 offices from coast to coast.