Borehole Geophysics
We log boreholes to define lithologic boundaries, moisture distribution, and radiological contamination in the vadose zone. Our slim-hole tools were developed by Three Rivers Scientific for direct push characterization at DOE sites beginning in 2005, and Cenozoic Resources acquired the tools and their designs in 2025. They are in contract service at DOE tank farms, where we supply, calibrate, and maintain the instruments and process the log data.
CR-HE/HR Direct Push Geophysical Tool Assembly
Specifications
The CR-HE/HR is a slim-hole geophysical tool assembly for direct push boreholes. Its gamma combination tool pairs CeBr3 and BGO detectors with an infrared temperature sensor, so contamination and temperature anomalies can be located in place before any sample is collected.
- Gamma combination tool: CeBr3 and BGO detectors, 1.5-inch outside diameter, 51 inches long
- Neutron moisture tool: 1.5-inch outside diameter, 29 inches long
- Additional tools: high-rate NaI gamma, beta, and passive neutron
- Deployment: 2 5/8-inch OD direct push tubing and monitoring casing
- Winch: cart-mounted portable system; no logging truck required
- Spectral logging rate: 100 to 200 seconds per 0.5 foot
- Gross gamma logging rate: 4 feet per minute
- Temperature: 0.50 °F detection limit, relative measurement optimized for anomaly detection
Calibration and QA/QC
Hanford Borehole Calibration Models
Our gamma and moisture tools are calibrated annually, and after major repairs, at the Hanford borehole calibration models. The spectral gamma models (SBK, SBU, SBT, and SBM) were built by DOE's Grand Junction office in the 1970s and are tied to DOE's primary borehole standards in Grand Junction, Colorado; each holds known concentrations of potassium, uranium, and thorium.
The neutron moisture models, shown here, are six steel-cased standards (6- and 8-inch casing at about 5, 12, and 20 percent moisture by volume) plus a thin-bed model. Our Chief Scientist co-authored their 1996 calibration (WHC-SD-EN-TI-306).
- Moisture calibration supported by MCNP modeling
- Background and daily functionality checks; pre- and post-survey source checks, with repeat logs within 10 percent RPD
- Depth calibration with a NIST-traceable tape, three runs within 1 foot
- Methods per API RP 33, ANSI N42.12 and N42.14, and ASTM D5753 and D6274; data validated under HASQARD Volume 3 and certified in each data package