Probe Technologies, Inc. provides both Macro-Core® and Dual-Tube® Sampling methods depending on soil types and depth of borings.
Macro-Core® Soil Sampling
Macro-Core® Soil Samples may be used in an open-tube or discrete point configuration. Opentube soil samples are used in shallow boreholes with no cave-in or slough. Probe Technologies prefers the use of the closed, discrete method of the Macro-Core®. We use the light weight center rods to keep the piston tip of the sample tube “closed” until the selected depth is reached. The rods are removed and the sampler is driven to next sampling interval. This method eliminates borehole slough and collapsed material. Additionally, using this method, we can blind probe to a specific depth and start sampling. A new clear, thin walled, PVC liner is used between sampling intervals.
Dual Tube 21 Soil Sampling
Dual-Tube® Soil Sampling uses two sets of probe rods for the collection of soil samples. The 2.25 inch probe rods are driven into the ground as the outer casings. The second set of probe rods are smaller, light-weight 1.25 inch rods used to keep a liner in place as the larger rods are driven into the formation. The inner rods are used to remove the liner and soil sample from the outer rods. Then a new liner can be placed on the inner rods and the next interval can be advanced. The advantages of using the Dual-Tube® are the collection of continuous samples within a sealed casing. A cased hole eliminates cross contamination while sampling through perched water tables and eliminates cave-in. Another advantage is a temporary or pre-packed mini monitoring wells can be installed inside the outer casings or bottom-up grouting can be performed as the probe rods are retracted.
Monitoring Well Installation
Probe Technologies has the capabilities to install up to 2-inch diameter monitoring wells per ASTM-D5092 using the Geoprobe® 6620DT. The unit has the power to spin 4.25 inch hollow stem augers and PVC wells can be installed up to 3o feet in depth, depending on soil conditions.
Screen Point 16 Groundwater Sampler
Probe Technologies uses Geoprobe® Screen Point 16 sampler to collect discrete groundwater samples from unconsolidated soils at depths up to over 100 feet below ground surface. The sampler uses a 1.6 inch stainless steel mesh screen that is completely sealed while the probe rods are driven into the ground. When the specific depth is reached, the screen is deployed into the saturated formation and the sample is collected using dedicated tubing, a peristaltic pump, and/or tubing check valve. After sampling the borehole can be properly grouted as the probe rods are retracted
Temporary Wells
Clay and silt formations are difficult and time consuming to use a screen point sampler for collecting groundwater samples. These types of soils require a temporary well to be installed. New ¾-inch diameter PVC well screen are lowered in the borehole to access the water bearing zone. Waters levels can be taken and samples can be collected when there is ample volume of water available. When sampling is completed the well screens and casings are removed and the borehole is abandoned.
Prepacked Well Screens
Prepacked Well Screens are small diameter wells that consist of PVC well screen pipe surrounded by filter pack sand and stainless steel wire mesh. Using the prepacked well screens assures the sand is around the screen portion of the well. These wells are installed by driving the 2.25 inch probe rods with an expendable point. The well is lowered down the center of the probe rods prior to removal. Fine sand and a bentonite seal is placed above the screen and finished with a flush mount or above-grade well protector. These wells are installed faster and more efficiently than traditional 2 inch auger drilled wells. Additionally, these prepacked wells are popular when using our 540MT Limited Access Geoprobe unit inside buildings or in areas where larger probes and drill rigs cannot access.
Soil Vapor Sampling
Probe Technologies has extensive experience in installing soil gas vapor probes, implants and sub slab vapor points. We use either the Geoprobe® machines or use hand tools to penetrate the surface and install any of the following vapor points;
Soil Gas Vapor Probes: These high purge vapor probes are constructed out of PVC through a shallow open probe hole. Completed with filter pack sand and a bentonite grout seal.
Vapor Implants: These are small diameter stainless steel wire mesh devices that are attached to HDPE tubing and installed at any depth, just above the water table. These single use implants are installed similar to the PVC vapor probes.
Sub Slab Vapor Pins: The most popular soil gas collection probes seems to be the sub slab vapor pins. We install the patented Cox-Colvin Vapor Pin®. These widely used sub slab vapor points are quickly and easily installed through the concrete floors of buildings and basements. Their tiny diameter brass and stainless steel pins are far less invasive and inconspicuous of all vapor sample ports.
