Geoprobe® a One-stop Cone Penetrometer Test Shop

Engineers who had gained valuable geotechnical experience working for the US Army Corps of Engineers Vicksburg District and the Waterways Experiment Station in Vicksburg, Mississippi, launched BURNS COOLEY DENNIS in 1985. Now with a staff of more than 60, the full-service Mississippi firm serves the entire state — top to bottom and east to west — while also venturing into the surrounding states as needed. The bulk of their work involves conducting geotechnical investigations with drill rig borings and lab testing in-house and providing materials engineering and testing for construction projects. They’re also known for offering a few specialized services: practical numerical modeling, geostructure design (e.g. anchored walls, soil anchor stabilization systems, soil nail walls), pile driver analyzer and other deep foundation testing, expansive clay analysis and forensic studies, and asphalt pavement physical and emulsion lab testing design and research.

“We have occasionally needed to add CPT to some of the geotechnical investigation projects, but have always had to subcontract that service in the past. Part of our long-term plan has been to add CPT capabilities, and we saw the benefit of adding a drilling rig like the 3126GT that could accomplish both traditional geotech and CPT,” Christian Jackson, engineer, said. “The 3126GT has the added benefit of allowing better access into difficult and restricted access locations.”

Doug Koehler, sales manager, spent three sweltering summer days setting the team up for success with training on what to do — and what not to do — with their new rig and cordless cone penetrometer testing (CPT) tooling system. The informative training left the team confident without a lot of lingering questions.

“Geoprobe^® has made it really simple to have a drill rig, CPT rig, and in-the-field training from one company. Geoprobe^® offers really good support. If we have a question about the rig or running CPT or getting supplies, we can call one place to get answers,” Jackson said.

Cordless cone penetrometer saves time, and they find setting up and running CPT easy thanks to a simple layout and features.

“Installing the anchor and adding additional pieces to increase depth of embedment is easy. Nothing is too difficult when running the CPT. There are tools to help efficiently remove rods from the ground,” Jackson said. “As the amount of energy required to push the cone varies between soil layers, the energy output by the rig can easily be adjusted. It’s as simple as pushing a button to adjust the speed and maintain the 2 cm/sec ASTM standard.”

They recently performed a job pushing the cone penetrometer 130-135 feet to measure strength gain for a levee being constructed in stages over weak clays in south Louisiana.

“That is the deepest CPT we have done with the rig, and it went great honestly,” Jackson said. “We’ve collected samples in 100 feet of sands and gravels and installed instrumentation, such as vibrating wire piezometers, in roughly 100 feet of clay. In both instances the 3126GT drilled a good hole.”

To them, the 3126GT is easy and efficient to operate while meeting not just their needs for cone penetrometer testing but other types of drilling as well.

“I talked with the driller and he says it does everything we need — hollow stem auger, dry augering, rotary drilling, direct push — extremely well. The driller has no complaints, and the engineers are very pleased with production rates," Jackson said. “The way it’s set up, the screen tells you everything you need to know about the status of your rig like when maintenance may be needed or making adjustments to power.”

The 3126GT also provides added benefits such as:

• conveniently leveling a pad on a steep slope or uneven terrain with the blade
• easily maneuvering through rough terrain in woods or washouts and down ditches with the tracks
• hauling water tank, augers, and other equipment on tool rack

“This is convenient when accessibility is difficult and you can’t get another truck with drill supplies to the location,” Jackson said. “It’s extremely efficient for most of the work we do. It’s easy to get into tight spots, difficult locations.”

Conversations in the field convey how attention to detail on the 3126GT makes jobs easier for the entire crew.

“The helper and driller described how the breakout clamp having places for equipment and tools like the sampler, pipe wrench, additional bits, and extensions makes the job less physically demanding and helps them be more efficient,” Jackson said. “The way things are laid out are really beneficial to the guy having to take everything on and off, which is easier than some of our other rigs."

Adding the 3126GT and CPT has not only made their jobs easier, it has increased their company’s service capacity.

“It expands our arsenal of all we can do as a company. We started looking for and gaining more CPT work since adding the 3126GT. It's the rig of choice for most of our projects now,” Jackson said. “Bringing CPT in-house helps with scheduling and flexibility on the job to add additional CPT or add an additional boring if data looks off.”