The Role of Confirmation Drilling in Aestus’ Process

The importance of confirmation drilling

Ground Truth Electrical Images

High-resolution electrical imaging, such as Aestus’ GeoTrax Survey™, generates powerful subsurface datasets—resistivity contrasts that delineate faults, NAPL zones, and contaminant flow pathways. But interpretation alone does not satisfy technical rigor. Confirmation drilling (CD) is the critical validation step that ties geophysical anomalies to physical evidence in the subsurface.

Much like a medical scan requires biopsy, geophysical imaging requires ground-truth sampling. Without confirmation drilling, resistivity anomalies remain hypotheses rather than actionable data.

Technical considerations:

  • Timing: Schedule confirmation drilling 8–10 weeks after imaging field work is completed.
  • Density: A maximum of 1-2 drilling locations per survey line should be budgeted for, but, in some circumstances, as few as 6-8 locations can validate up to 20 images, with 2–3 samples per location.
  • Method: Monitoring wells are preferred over borings in fine-grained media, ensuring contaminants (especially NAPL) are not overlooked.

The result is a calibrated conceptual site model (CSM) where geophysical anomalies are directly linked to measured contaminant concentrations and stratigraphic features. This integration reduces uncertainty in remedial design, strengthens regulatory defensibility, and optimizes placement of injection and extraction wells.

In complex geology, confirmation drilling is not optional—it is the keystone that transforms geophysical imaging into a reliable remediation roadmap.

Untargeted confirmation drilling
Confirmation drilling into a targeted location using GeoTrax Survey images
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    Samantha Frandsen
    Since joining Aestus in 2018, Samantha has performed all aspects of the Aestus project lifecycle, including acquisition field work, processing of geophysical data, data integration, 3D visualization, and reporting. As project manager, she oversees a variety of projects completed at complex sites across the United States and strives to help our clients efficiently leverage Aestus’ high-resolution GeoTrax Survey™ data to improve understanding of subsurface conditions. When she’s not investigating what’s below the ground, Samantha enjoys exploring all the above-ground fun her Stateline (South Lake Tahoe), NV home has to offer via trail running, mountain biking, and snowboarding. Samantha is based out of Stateline, Nevada.

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    Madison Culver
    Madison Culver, M.Sc.
    Staff Geologist / Field Technician
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    Madison previously worked at an environmental consulting firm in Dallas, Texas, where she performed soil/groundwater investigations/reporting, PFAS sampling programs, and Environmental Site Assessments.

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    Since joining Aestus in 2018, Samantha has performed all aspects of the Aestus project lifecycle, including acquisition field work, processing of geophysical data, data integration, 3D visualization, and reporting. As project manager, she oversees a variety of projects completed at complex sites across the United States and strives to help our clients efficiently leverage Aestus’ high-resolution GeoTrax Survey™ data to improve understanding of subsurface conditions.

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