Geophysical Services

Ramseur's Mill

Battle Site

Historical Sites

Locating buried features, including:
- building footprints
- foundation stones
- stone floors
- cellars
- privies
- historic roads

Clemson Woodland Cemetery

Cemeteries

Locating unmarked graves
Delineating cemetery boundaries
Identifying unused areas for future grave plots
Mapping and surveying

Underground Storage Tanks (USTs)

Subsurface Investigation

Utility location, such as:
- underground storage tanks
- sewer lines and septic systems
Landfills and trenches
Other environmental services

Non-intrusive geophysical survey techniques

Ground Penetrating Radar (GPR)
Electrical Resistivity
Magnetometer Surveys
Gradiometer Surveys
Aerial Photography
GIS and GPS

Equipment

GPR

GSSI SIR3000 GPR system with 350 mHz antenna

GSSI Utility Scan with 400 mHz hyper-stacking antenna

The GPR system sends pulses of electromagnetic energy or radar into the earth which propagate through the subsurface and are partially reflected back upon encountering material with different edielectric properties (conductivity). This allows us to observe changes in the subsurface, for example, the difference between backfill in a grave shaft and the surrounding, undisturbed soil.

Example Unmarked Burial Transect

Electrical Resistivity

AEMC 6470 resistivity meter with a four electrode Werner array

Geonics EM-31 terrain resistivity/conductivity meter

Our custom-built resistivity system employs an AEMC 6470 resistivity meter and a four electrode, linear Werner Array designed for detecting shallow ground disturbance. This system provides a second line of evidence to evaluate anomalies detected by the GPR system. The combination of GPR and resistivity improves the accuracy of the geophysical surveys and significantly reduces the number of false positives. Electrical resistivity surveys can detect buried metallic objects (USTs, drums, utilities...) and identify areas of subsurface disturbance such as former waste disposal pits or unmarked graves. An ER survey can also used to map the footprint of former structures by imaging the difference between soil and foundation materials.

Magnetometer

GEM Systems Overhauser Walking Magnetometer

Geometrics Cesium Vapor G858

An Overhauser Walking Magnetometer is used to conduct magnetometer and gradiometer surveys. This magnetometer has been used to detect ferrous objects and areas of magnetically enhanced soil such as burned structures.

For more sensitive surveys a Geometrics Cesium Vapor G858 Magnetometer can be used to measure very subtle changes in the earth’s magnetic field due to past site occupations. This system is commonly used in archaeology surveys. The magnetometer data is downloaded and processed to produce an image of anomalies across the survey grids.

GPS

Juniper Systems Geode GNS3S

The Juniper Geode is a GNSS receiver with sub-meter accuracy. It is used in conjunction with Esri's ArcGIS Online application, Field Maps, to record spatial data in our surveys.