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Specialty Materials Testing

In-Situ Thermal Resistivity Surveys

An in-situ thermal resistivity survey brings the test equipment to the project site and measures soil or backfill in place at selected locations. The result documents the material’s thermal behavior under the density, moisture, temperature, and structure present when the survey is performed.

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Service overview

What this service involves

Calicore begins by reviewing the proposed cable route, duct-bank alignment, substation area, boring information, plans, and the thermal designer’s requested locations or design questions. Test points are selected to represent important soil units, installation depths, material transitions, crossings, or areas where an assumed thermal rho could control the electrical model.

At the site, the test area is exposed or accessed under the project’s excavation, utility-clearance, and safety procedures. A thermal needle probe is installed with controlled contact in suitable soil or backfill, the material is allowed to reach an appropriate starting condition, and its temperature response to a controlled heat input is recorded. Replicate readings, field observations, location data, current moisture condition, material description, and deviations are documented so the reported value is not separated from the conditions that produced it.

An in-situ point describes the condition at that place and time. It does not show the complete moisture-dependent dry-out behavior of the soil. When long-term drying is part of the design question, Calicore can collect representative bulk samples during the same mobilization for laboratory moisture-density characterization and a multi-point thermal dry-out curve.

Step by step

How the process works

The exact scope is matched to the project, but a typical assignment follows these steps.

  1. 01

    Define the field question

    We review the route, installation depth, plans, existing borings, proposed materials, required output, site access, utility-clearance process, and whether laboratory samples are also needed.

  2. 02

    Select and prepare test locations

    Stations are chosen around representative soils, material transitions, critical facilities, crossings, or installed backfill. Safe access or excavation is coordinated with the owner or contractor.

  3. 03

    Measure the in-place material

    A thermal probe is installed with controlled contact in suitable soil or backfill. Temperature response, repeat readings, material observations, location, and the current field condition are recorded.

  4. 04

    Map, report, and relate the data

    Results are tied to each test point and clearly identified as current in-situ conditions. When ordered, bulk samples are cross-referenced to laboratory moisture-density work and dry-out curves.

Review criteria

What the cable or thermal designer needs from an in-situ survey

A field thermal point is useful only when the designer knows exactly where, how, and under what material and moisture conditions it was measured.

What you receive

Typical project deliverables

  • Survey and test-location plan
  • In-situ thermal needle-probe measurements
  • Mapped locations, photographs, and field-condition log
  • Thermal results with material, moisture, and method context

Common project needs

When this service is useful

  • Underground cable-route investigations
  • Substations, data centers, and utility campuses
  • Existing soil or installed backfill condition checks
  • Projects combining field points with laboratory dry-out curves

Frequently asked

In-Situ Thermal Resistivity Surveys questions

What happens during a thermal survey?+

Calicore reviews the route and objectives, coordinates access and excavation, installs a thermal probe in suitable in-place material, records the temperature response and field conditions, and issues location-based results. Representative samples can also be collected for laboratory curves.

Does a field point replace a thermal dry-out curve?+

No. A field point documents the current in-situ condition. A laboratory dry-out curve shows how the material changes across multiple moisture states. A project may need one or both.

Can Calicore travel outside California for a thermal survey?+

Yes. In-situ thermal-resistivity surveys are available nationwide when the scope and mobilization justify field work.

Who provides excavation and utility clearance?+

Responsibilities are established in the proposal. The site owner or contractor commonly provides safe access, utility clearance, traffic control, and excavation or test pits, while Calicore defines the measurement-access requirements and performs the thermal work.

Technical guides

Learn more about in-situ thermal resistivity surveys.

Use these technical articles to understand the methods, limitations, evidence, and decisions behind the service.

Related services

View Specialty Materials Testing
Materials TestingUnderground Cable Route Thermal SurveysMaterials TestingInstalled Thermal Backfill Field TestingMaterials TestingThermal Resistivity Testing

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What to send us to begin

Send a short description of the work, any plans, specifications, or photographs you have, and tell us what you need the service to provide. Include a project location if it applies.

Request a proposal