In December 2024, the Federal Energy Regulatory Commission (FERC) released the final Environmental Impact Statement (EIS) for the Ridgeline Expansion Project, proposed by East Tennessee Natural Gas, LLC.
According to a press release from the FERC, this initiative aims to construct approximately 122.2 miles of 30-inch-diameter pipeline across multiple counties in Tennessee, enhancing natural gas transportation capacity to the Tennessee Valley Authority’s Kingston Fossil Plant. The project's scope includes not only the new pipeline but also the removal of about 24 miles of previously abandoned pipeline segments, which will be replaced with the new mainline pipe in the same trench.
The EIS concluded that, with proper mitigation measures, the project's environmental impacts would be less than significant. This determination underscores the critical importance of meticulous planning and data accuracy in large-scale utility expansion projects. A pivotal aspect of such planning is the accurate capture of subsurface infrastructure data.
The Importance of Accurate Subsurface Data
Subsurface infrastructure encompasses a complex network of utilities, including water pipes, gas lines, electrical cables, and telecommunications fibers. Accurate mapping of these underground assets is essential for several reasons:
- Safety Assurance: Unintended strikes on underground utilities during excavation can lead to hazardous situations, endangering workers and the public. Precise subsurface data helps prevent such incidents by informing construction teams of existing utility locations.
- Cost Efficiency: Unexpected encounters with uncharted utilities can cause project delays and escalate costs due to repairs and legal liabilities. Investing in accurate subsurface mapping can lead to significant cost savings by reducing these unforeseen expenses.
- Design Optimization: Comprehensive knowledge of subsurface conditions allows engineers to design projects that avoid conflicts with existing utilities, streamlining the construction process and enhancing overall project efficiency.
Subsurface Utility Engineering (SUE): A Structured Approach
To systematically manage subsurface data, the industry employs Subsurface Utility Engineering (SUE), a practice that integrates civil engineering with advanced geophysical technologies. SUE classifies utility data into four quality levels, each representing a different degree of accuracy:
- Quality Level D (QL-D): Information derived from existing records or verbal accounts
- Quality Level C (QL-C): Data obtained by surveying visible utility features and correlating them with existing records
- Quality Level B (QL-B): Application of surface geophysical methods to detect and map the horizontal position of subsurface utilities
- Quality Level A (QL-A): Precise mapping through non-destructive exposure methods, providing exact horizontal and vertical positions of utilities
Implementing SUE practices ensures a higher degree of confidence in subsurface data, thereby mitigating risks associated with utility conflicts during construction.
GPRS uses SUE Level 2-equivalent methodology and equipment to locate underground utilities with an accuracy rate of 99.8%. While we don’t conduct SUE work ourselves, our services allow a SUE Level 1 investigation to be performed more efficiently, eliminating the need to waste thousands of dollars on exploratory potholing.
Technological Advancements in Utility Mapping
Recent technological innovations have significantly enhanced the accuracy and efficiency of subsurface utility mapping. Some of the technologies employed by professional utility locating companies include:
- Ground Penetrating Radar (GPR): Utilizes radar pulses to image the subsurface, allowing for locating and mapping of buried utilities
- Electromagnetic (EM) Locating: Detects the electromagnetic signals radiating from metallic pipes and cables
- Geographic Information Systems (GIS): Integrates spatial data into comprehensive maps, facilitating better planning and decision-making
These tools, when used in conjunction, provide a detailed and accurate representation of underground utilities, essential for the successful execution of large-scale projects.
Let GPRS Provide You With Accurate, Complete Infrastructure Data
The Ridgeline Expansion Project exemplifies the complexities involved in modern utility infrastructure development. Accurate subsurface infrastructure data capture is not merely a procedural formality but a foundational element that ensures safety, cost-effectiveness, and efficiency. As utility networks continue to expand and evolve, the integration of precise subsurface data into planning and implementation processes will remain indispensable for the successful delivery of large-scale projects.
GPRS utilizes industry-leading technology, training, and methodology to help you Intelligently Visualize The Built World® while staying on time, on budget, and safe.
What can we help you visualize?
Frequently Asked Questions
Can you find PVC piping and other non-conductive utilities?
GPR scanning is exceptionally effective at locating all types of subsurface materials. There are times when PVC pipes do not provide an adequate signal to ground penetrating radar equipment and can’t be properly located by traditional methods. However, GPRS Project Managers are expertly trained at multiple methods of utility locating.
Can GPR be used to verify known measurements?
We can use GPR to cross-check the measured depth and location of a located utility with existing as-built plans in order to verify the accuracy of plans.
