Geophysical Surverys and Subsurface Investigations for Engineered Solutions:
- GSSI SIR3000 Ground Penetrating Radar System
- Strata-Scout Single CHannel Resistivity Meter
- Geonic's EM-31 Terrain Conductivity Meter
- MF-1 Fluxgate Magnetometer
- Bartington MS3 Magnetic Susceptibility Meter
- AGI Super Sting Resistivity System
- Geometrics Cesium Vapor G858 Magnetometer
Ground Penetrating Radar
GPR surveys are used to located buried tanks and mapping out remnant infrastructure at commercial, industrial and residential facilities. When combined with the magentometer, the GPR does an excellent job of imaging subsurface utilities.
GPR survey to located unmarked utilities (left). SIR3000 Data recorded is used to select resolution of the GPR data and target depth (right).
GPR cross-section (above) showing sewer line below concrete slab, note the rebar produces numerous hyperbola along top of profile.
3.3 foot GPR depth slice (plan view) of anomalies representing a non-ferrous conduit (below).
We have also completed many geophysical surveys in historic cemeteries to identify unmarked graves and delineate cemetery boundaries. Critical infrastructure development can involve negotiations for relocating graves in historic cemeteries. Our staff has experience working with families of the descendants and assisted in providing closure in these sensitive situations.
GPR survey to located unmarked graves in historic cemetery (left) and three-dimensional view of GPR grid showing reflections off the base of the grave shaft (right).
GPR survey to located lost cemetery where anomalies were marked on the ground surface (left) and grave locations were ground-truthed with plow zone stripping (right).
Electric Resistivity Surveys
Electrical resistivity surveys are useful for detecting buried metallic objects (USTs, drums, utilities..) and identifying areas of subsurface disturbance such as former waste disposal pits or unmarked graves. An ER survey can also be used to interpret the depth to bedrock. Seramur and Associates uses a Soil Test, Inc., Strata-Scout electrical resistivity system with a four electrode, linear Werner Array for most of these applications.
Strata-Scout set up with variable distance four electrode Werner Array for imaging deep anomalies such as depth to bedrock (left). Changing the electrode spacing measures ER at different depths. The ER system set up with fixed distance electrode spacing for imaging buried utilities or unmarked graves (right).
Results of an ER survey at a historic cemetery showing north-south aligned rows of unmarked graves.
Seramur and Associates provide two options for magnetometer surveys. A MF-1 Fluxgate magnetometer provides an excellent method for identifying buried ferrous objects such as tanks, pipelines, drums, or buried industrial debris. It is a quick, inexpensive and nonintrusive method for locating USTs and buried ferrous objects.
Magnetometer survey with the MF-1 to determine the number and location of USTs at a closed manufacturing plant (left). MF-1 locates the end of the first UST (right).
For more sensitive surveys a Geometrics Cesium Vapor G858 Magnetometer is used to measure very slight changes in the earth’s magnetic field due to the presence of subsurface features including foundations, fence lines, historic roads and trails. This system is commonly used in archaeology surveys. The magnetometer data is downloaded into MagMapper software producing a plan view contoured image of the survey grids.
Gradiometer survey at a historic archaeological site for DelDOT using the Geometrics Cesium Vapor G858 Magnetometer.
Terrain Resistivity, Conductivity Surveys
Seramur and Associates uses a Geonics EM-31 system to map changes in the resistivity and conductivity along a survey grid. Anomalies identified in these surveys indicate subsurface changes such as unmapped landfills or disposal areas and buried ferrous objects. This noninvasive technique is useful to identify source areas of contaminant plumes.
The EM-31 can be used to measure changes in conductance of a profile 15 to 20 feet below the instrument height. When the instrument is operated using the “in-phase” mode it is useful in identifying buried metal objects. This instrument is sensitive to noisy environments with overhead power lines metal buildings or metal objects adjacent to the traverse so the EM-31 is used in selective environments.
Terrain resistivity, conductivity survey of former retail facility prior to re-development as a medical complex (left).
EM-31 meter showing controls and connection for data recorder (right).