Soil Resistivity Atlas
Proprietary field data from 500+ Wenner-array traverses — powering precision grounding design since 2002.
Two Decades of Soil Resistivity Field Data
The E&S Soil Resistivity Atlas is a proprietary collection of Wenner four-electrode traverse measurements gathered by E&S Grounding Solutions, Inc. engineers during real-world grounding design projects. Every record represents an actual field measurement — not a modeled or estimated value.
Each traverse in the database has been processed to produce a two-layer earth model consistent with the requirements of IEEE Std 80 (Guide for Safety in AC Substation Grounding) and IEEE Std 81 (Guide for Measuring Earth Resistivity, Ground Impedance, and Earth Surface Potentials).
The atlas is continuously updated as E&S engineers complete new projects. Subscribers always have access to the most current dataset.
All measurements collected and processed per IEEE standards for substation grounding safety.
Every traverse represents an actual measurement taken by a licensed E&S engineer on a real project site.
Processed Sunde two-layer earth models (ρ₁, ρ₂, h) ready for direct use in CDEGS and other grounding software.
All traverses are geocoded and displayed on an interactive map, filterable by soil class and region.
Soil Class Distribution
The 508 geocoded traverses span all five IEEE-aligned soil resistivity classes, with the majority falling in the Low to Moderate range — consistent with the irrigated agricultural and suburban terrain of Southern California.
How the Data is Collected
Each traverse uses the Wenner four-electrode method per IEEE Std 81. Electrode spacings are systematically varied to profile resistivity at multiple depths.
Raw apparent resistivity data is processed using the Sunde graphical method and least-squares curve fitting to derive a two-layer earth model (ρ₁, ρ₂, h).
The surface resistivity value (ρ surface) is used to classify each traverse into one of five IEEE-aligned soil classes for quick reference and comparison.
Each traverse location is geocoded from the project address record and reviewed for accuracy. Locations are stored as decimal latitude/longitude for mapping.
All measurements are performed by licensed professional engineers. Data is collected using calibrated Megger DET4TC2 and AEMC 4620 earth resistance testers. Results are reviewed and signed by a California-licensed PE prior to inclusion in the database.
Unlock the Full Atlas with a Pro Subscription
The public map shows location and soil class for every traverse. A Professional or Firm subscription unlocks the complete dataset — raw measurements, two-layer model parameters, IEEE Annex B results, and project metadata — for every record in the database.
- Raw Wenner array measurements for every traverse
- Computed two-layer model (ρ₁, ρ₂, h) and RMS error
- IEEE Annex B computed results
- Project number and job ID
- Full historical database export (CSV)
- Access to the interactive map with all 508+ pins
- Unlimited soil resistivity calculations
- Seasonal correction factors
- PDF report generation
- Ongoing database updates as new traverses are added
Who Uses the Atlas
Use historical traverse data from nearby sites to validate new measurements, identify anomalies, and benchmark soil conditions against regional norms before finalizing a grounding grid design.
Soil resistivity is the primary driver of corrosion rate for buried metallic structures. The atlas provides a regional baseline for cathodic protection design and pipeline risk assessments.
Solar and wind project developers use the atlas to perform preliminary grounding feasibility studies before committing to costly field campaigns, reducing pre-development costs.