Accurately locating buried utilities and obstructions is essential to any project where invasive activity (drilling, excavation) is planned.  Public services (811) provide free utility locates in some areas, but we provide an expanded scope of investigation and enhanced results to promote job site safety.  Logic Geophysics uses industry best practices for locating subsurface utilities using GPR data “grids,” rather than the "walk and mark" method inexperienced practitioners typically employ.  We offer on-site data processing, and a comprehensive range of reporting options to suite your budget and needs.  We can also provide 3D data results compatible with AutoCAD and other software as desired.

3D data set and interpretations generated from processed GPR data and incorporated into client GIS platforms

3D data set and interpretations generated from processed GPR data and incorporated into client GIS platforms

“ Missing” culvert at a work site that was detected with GPR then excavated

Missing” culvert at a work site that was detected with GPR then excavated

Applications: GPR can detect metallic and nonmetallic (plastic/HDPE) buried pipes.

Electric
Water
Communication Lines
Oil and Gas
Sewer and Storm
Other Primary and Secondary Utilities
Septic Systems
Rebar/PT Cable


Factors in the GPR investigation of utilities

Here are some of the questions we'll ask to help plan your project:
1) The number and type of utilities being located, such as water, power, and others - having an idea of the targets beforehand allows us to plan the optimal survey.
2) The size of the area to be surveyed - the time and cost of the survey depend in part of the area coverage needed.
3) The depth of the buried utilities - We use a range of frequencies to provide optimal imaging of targets at different depths.
4) The type of soil onsite - Gravels and sands are typically amenable to GPR signal penetration, but clay is not. How well pipes can be detected can also depend on the water content of the soil.
5) Site access - the surface needs to be cleared of obstructions and metal object for us to survey effectively, and if site access is difficult and/or remote, the cost of logistics increases.
6) The scope of the project and the desired format of results - a full report costs more than ground markings.

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GPR data collection in winter at the Anchorage International Airport

GPR data collection in winter at the Anchorage International Airport


The importance of gridded data collection: We always collect data in a grid, with parallel and perpendicular transects forming a square or rectangle on the surface.  Collected this way, the GPR data can be processed in depth slices, which provides the most accurate subsurface imaging solution.  Although this methodology is more time consuming and therefore expensive, it's the only reliable way to implement GPR for locating utilities. 

Utilities detected with GPR, exposed after trenching

Utilities detected with GPR, exposed after trenching

Map view of coherent anomalies associated with utilities

Map view of coherent anomalies associated with utilities

Common Questions about Utility Locates with GPR

Can GPR find plastic pipes?  Yes - our technology and expertise applied to your project can successfully interpret data anomalies characteristic of different pipes including plastic, depending on site conditions.

Can GPR determine the type of utility?  Determining the type of utility is difficult, but with our GPR expertise and years of experience, our interpretation can yield insights into which utilities are being imaged.

How accurate is GPR at locating utilities? Simply put, GPR is the most accurate method available.  Often we can located objects within an inch of their true location.  Depth accuracy is typically 10-15%; and we provide advanced services, at additional cost, that can reduce depth uncertainty.

Can we get a permanent record of the results? Yes, of course!  You own the data if you're paying for the project, and we're happy to provide them in whatever format you desire.  Available products include georeferenced grid images, grid coordinates or real-world coordinates of interpreted results, and 2D or 3D images of the subsurface results.

What qualifications do you have? We are the GPR experts in Alaska!  Logic's Chief Geophysicist, Esther Babcock, has her Ph.D. in GPR imaging and years of project experience throughout Alaska, North America, and the world.  We've cleared hundreds of locations for drilling and excavating operations with a 99.5% success rate.