Every member of our field team has the following certifications:
Some members of the field team also have the OSHA HAZWOPER supervisor certification as well as the NOLS Wilderness First Aid certification.
Electrical current (safe level) is injected into the ground, and the voltage is measured coming back out. Ohm's Law is used to calculate resistivity:
Aestus likes to incorporate as many data sets into each 3-D model as possible. The more data that can be viewed together in one place, the better chance there is of seeing trends in the data and developing a better understanding of the site.
3-D Models typically include the following data sets, at a minimum (assuming data is available from client):
Historically, both methods generally agree in terms of identifying impacted zones, but GeoTrax Survey™ often provides more context. For example, one energy firm compared GeoTrax Survey™, Laser-Induced Fluorescence (LIF), and soil samples and found that LIF sometimes produced false positives where GeoTrax Survey™ and soil borings showed no contamination. These false positives were viewed as a potential liability.
As another example, the image below provides a comparison of GeoTrax Survey™, TarGOST® (Tar-Specific Green Optical Screening Tool), and a traditional soil boring at a former tie treatment facility.
Your family pet is ailing so you consult a veterinarian who runs a few simple tests which indicate a more serious issue requiring surgery. The vet performs an MRI high resolution scan to identify exactly where/what is the root cause of the problem so the surgery can be targeted. The medical industry knows empirically that the investment in the scanning data (only ~10% of the surgery cost) is essential to facilitate successful surgery and minimize liability.
Similarly, if a site owner believes its site might be “sick” (environmentally impacted) it is typically prudent and necessary to spend up to ~10% of the projected remediation costs to perform Ultra-High Resolution Site Characterization (UHRSC) to target remediation work. The resulting data dense conceptual site model (CSM) identifies root cause(s) of site issues and facilitates faster and cheaper remediation, while reducing potential trailing liabilities.
Aestus’ proprietary method of data collection and processing (GeoTrax Survey™) is up to several orders of magnitude more sensitive than traditional methods (Miller et al., 2014), ensuring the resulting images are more representative of the subsurface. ERI data are collected as raw resistivity data that have to be inverted (i.e., processed) to produce a model of the resistivity structure of the subsurface. The sensitivity refers to how well the inversion can detect spatial variability of resistivity. Greater sensitivity yields higher image accuracy relative to representing subsurface conditions, which leads to a more “drillable” image.
Aestus can:
It should be noted that slurry walls can be observed on a one-time basis to evaluate if flow is moving beneath or laterally around the wall. Additionally, temporal (GeoTrax Monitoring™) data can be used to test the effectiveness of the wall at installation and over time. This is especially helpful if the wall is a permeable reactive barrier and the flow dynamics need to be assessed.
Aestus field crew members currently have or have recently held the following railroad safety certifications:
Depending on the railroad, additional training or safety classes may be required.
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