GeoCore: Kansas Drilling Firm.  Environmental, Geotechnical, Exploratory, and Water Supply Drilling.

     Geoprobe® 

Direct Push Services

GeoCore currently utilizes a 2003 Geoprobe® 540UD probing machine mounted on a 2003 Ford F350 truck for direct push soil and groundwater sampling capabilities.  This probing machine is extremely versatile in performing continuous soil sampling, electrical conductivity logging, discrete interval soil sampling and discrete interval groundwater sampling in unconsolidated sediments.  Due to its small size and 4-wheel drive capability, this unit is able to access difficult sampling locations.

Some of the advantages of the Geoprobe® 5400 are:

  • Direct push sampling with little or no investigative derived waste and minimal disruption to property.

  • Small 4x4 truck access to difficult terrain.

  • Fast efficient setup and sampling allowing for a high volume of samples collected per day.

Tooling which is provided with this rig consists of 1.25” probe rods, macro-core sampler, discrete interval macro-core sampler, electrical conductivity logging and screen point groundwater.

The Geoprobe® 5400 is a compact, convenient, hydraulically powered percussion-probing machine.  It can be swiftly folded out the truck for operation.  The Geoprobe® uses static force and a percussion hammer to advance small-diameter sampling tools.  It provides an economical way to carry out sampling operations and generally operates at depths of 30 to 60 feet; but, depending on soil conditions, can go deeper. Sampling is efficient with 10 to 30 sample locations per day. Stroke is 54 inches, enabling the Geoprobe® to accept a variety of probe rod lengths. The probing tools not only create small diameter holes that minimize surface disturbance, but little cuttings are produced during the sampling process. Tools can be interchanged at any time.

         Direct Push Electrical Conductivity Logging

A percussion soil probe system designed for direct sensing of soil conductivity.  The probe is approximately 1-1/8 inches in diameter with isolated contacts. The probe is advanced into the ground by a hydraulically powered pushing and percussion mechanism. A signal cable attached to the probe is run through the inside of the rod to a laptop computer-based data recording system. Depth measurements are obtained from a stringpot system configured to measure the distance from the driving mechanism to the ground surface. Data derived from this system is used to both determine the depth of the probe and the probing speed. Conductivity measurements are displayed with respect to depth in near-real-time on the computer screen. Data was recorded in spreadsheet format and downloaded at the end of each field day.

High conductivities are associated with clayey soils, low conductivities with sandy and gravely soils, and sand/silt/clay mixtures have conductivities that lie somewhere in between. Conductivity levels change somewhat from one sample location to the next; however, the clayey soils at the site tend to have conductivities in the range of 60 to 140 mS/m and the sands about 30 to 40 mS/m, with gravels generally showing a conductivity dip of about 5 to 10 units below the level for a sandy soil. Because the conductivity varies somewhat for a given soil type between sample locations, comparing the conductivity log with a soil boring log or CPT soil classification log is essential to properly interpret the conductivity log. Changes in conductivity are caused by changes in soil type, water content, and soil or groundwater contamination. Accordingly, when used alone, the conductivity log leaves some doubt regarding an accurate soil classification. It is quite effective, however, at delineating changes in the subsurface properties.

         Macro-Core soil sampling

The Macro-Core soil sampler collects core samples of unconsolidated materials 1-1/2 inch in diameter. These unconsolidated materials may include soils, sediments and waste materials or mixtures of these. The device works best in medium to fine grained cohesive materials such as silty/clay soils or sediments. When using the plastic core catchers, the Macro-Core catcher can also be used to sample medium to coarse grained sandy materials with some fine to medium gravels. 
The Macro-Core sample can be used with an open nose cone in stable soils or a closed nose cone in unstable materials to prevent unwanted materials from entering the sampler till the sampling depth has been reached.

The Macro-Core soil sample can be captured in clear plastic liners. The liners are inserted into the sampling tool prior to being pushed into the soil. The most common types are PETG and PVC liners. These are clear and give you a good view of the soil cross section after retrieval. PVC plastic core catchers can be used in the end of these liners for sampling unconsolidated soils

 

 

 

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