Geophysical Engineering Services
Detecting the Unexposable
Geophysics is the use and/or interpretation of physical properties of the earth to determine subsurface conditions. Geophysical methods are usually further sub-divided into active and passive methods. Passive methods include methods that detect natural variations within the natural fields associated with the Earth, such as magnetic and gravitational fields.
Active methods, such as exploration seismology and electromagnetic methods, incorporate produced energy, or signal, that is sent into the subsurface and altered based on the medium in which it travels. Although geophysical techniques were often developed for purely economic benefit, today they have morphed into tools that can be successfully applied and used to aid the civil and environmental engineering disciplines.
NTH uses ground penetrating radar (GPR) technology on a daily basis to locate utilities, buried drums, USTs, and vaults, and have also evaluated and interpreted rebar spacing in concrete slabs, rebar and grout placement in CMU walls, void detection near pavements and utilities, and field location of mid-nineteenth century graves.
NTH also incorporates and commonly uses a relatively new seismic technique called Multi Channel Analysis of Surface Waves, or MASW. In fact, NTH is one of a handful of companies in the United States that use this technique in a wide variety of applications (typically to determine variations in shear wave velocity of subsurface materials to ~ 100 feet).
Typical applications include seismic site classification, void detection above utilities, lithology mapping, subsurface detection of soil failure envelopes, landfill limit delineation, and compaction/stiffness estimations of in-place soils. We have used this technique successfully to search for karst features beneath a major automobile manufacturing facility, to define soil failure characteristics above a large gas pipeline being installed with Horizontal Directional Drilling (HDD) methods, and developing/existing voids above interceptor sewers (well over 20 miles of surveys).
NTH’s Value Added
NTH employees are trained professionals with state of the art industry technology. Our long history of geophysical knowledge is proven to meet our clients’ needs.
We find information that is hidden and often times intended to remain hidden. We will then walk you through the steps needed to ensure the problem does not persist. In the end, we provide our clients with results they know they can trust.