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High-Resolution
Site Characterization

Tool comparison
Field footage of one rod change: the tool going into the ground, the next rod carried over to the rig and screwed on, and the rig hammering it down.

HRSC, defined High-Resolution Site Characterization

EPA’s definition: “High-resolution site characterization (HRSC) strategies and techniques use scale-appropriate measurement and sample density to define contaminant distributions, and the physical context in which they reside, with greater certainty, supporting faster and more effective site cleanup.”

One real OIHPT push plotted against depth from 0 to 40 feet, in three columns: HPT injection pressure in PSI, estimated K in feet per day, and fluorescence in % AF. The 20 readings per foot button zooms to the foot from 26.5 to 27.5 feet and marks each of its readings. There the estimated water table sits at 26.9 feet. Low HPT pressure, high estimated K and fluorescence at the water table together indicate likely mobile LNAPL in permeable sand.
HPTPSI
Est Kft/day
Fluor.% AF

  1. The foundation of HRSC is the recognition that subsurface heterogeneity occurs at scales often too fine for conventional investigation methods to resolve.

  2. Thin clay lenses, perched NAPL zones, and preferential flow pathways can occur at the centimeter-to-meter scale. Soil samples collected at 2–5 foot intervals leave data gaps by design, and features this thin can fall between them.

  3. HRSC logging tools measure continuously as they advance through the subsurface, recording lithologic, contaminant, and hydraulic data 20 times per foot.

  4. Because the logs are viewed in real time, laboratory samples can be targeted to the intervals that matter, and fewer are needed.

  5. Most HRSC tools provide real-time data evaluation, reducing the need for multiple mobilizations by allowing the investigation scope to be adjusted in the field as data are collected.

  6. With thousands of data points per log from multiple data streams, we are able to develop more precise and accurate conceptual site models rapidly.

The case for HRSC

With a more accurate site model, the decisions that follow are made with more confidence: which remedy fits and where it goesSource 1, and where monitoring wells are screenedSource 2. The whole project also typically costs less and finishes soonerSource 3.

Sources

  1. “HRSC is a highly effective strategy to obtain the detailed geologic, hydrogeologic and contaminant information necessary to select and design remedial technologies matched to the scale of the spatial attributes of the subsurface problem.”

    U.S. EPA, CLU-IN: What Is HRSC?

  2. “If monitoring wells are constructed as part of confirmatory sampling, use the soil property and contaminant data from the direct sensing to design screen intervals that accurately sample the strata of concern and ensure screens do not overlap and connect multiple flow zones.”

    U.S. EPA direct sensing HRSC guidance, 2025, section 3.6 (PDF)

  3. “Typically reduced overall project costs and duration.”

    U.S. EPA, 2025, summarizing its 2023 study (PDF)

    “For three common types of petroleum UST release scenarios the expert panel concluded HRSC could save on average:
    9% to 19% in project costs.
    3 to 8 years in project time.”

    U.S. EPA Office of Underground Storage Tanks, 2023 study (PDF)

Compare the logging tools, or tell us about your site and we’ll recommend one.

HRSC technical resources

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