The 4-Twenty Project
New Geoprobe® SDT60 Weighted Wire Line System Obtains High-Quality Soil Samples in Less Time
Tim Gallagher, President of Enviroprobe Services in Moorestown, NJ, was recently awarded a project that required a 420-ft soil boring outside of Newark, NJ. Tim was no stranger to Geoprobe® sonic tooling as his crew had already performed several soil borings using the Geoprobe® SDT60 (Sonic Dual Tube system for 6-in. casing). Tim saw the SDT45 Weighted Wireline system (WWL) demonstrated at the Geoprobe® Sonic Field Day in New Jersey last fall, and read about it in the 2015 Spring Probing Times, so he asked if Geoprobe® could assist with the project.
Sure enough. The tooling engineers were in the late stages of developing a weighted wireline system for SDT60. “The timing was perfect, and the site conditions couldn’t have given us a better test of this new tooling system,” Jed Davis, Geoprobe® Tools Engineer, said. “The geology was predominately sedimentary rock throughout the entire 420-ft. boring which made it ideal for the weighted wireline system.”
The first 60 feet was mostly unconsolidated so Jason Kuni, Lead Driller for Enviroprobe Services, used a conventional SDT60 system using 2.25-in. center rods. Brian Sweeney and Paul Mancuso were also part of the drilling team. After 60 feet, the formation became more consolidated, so the crew set the 2.25-in. center rods aside and implemented the weighted wireline with the SDT60 system. The crew went on to complete the boring with a total depth of 420 feet, collecting 10-ft. continuous soil cores at each interval.
Jed, who was onsite testing the equipment, said, “As the drilling got deeper, the weighted wireline proved its worth.” Since the sample barrel and weight assembly are tripped in and out together with only the use of the winch, the speed and efficiency of the system becomes more and more evident the deeper you go. Jed explained: “The winch had a line speed of 130 feet-per-minute, so tripping in and out at, say 250 feet, only took about 2 minutes one way. Just as a comparison, it took 14 minutes to trip 250 feet of 2.25-in. center rods out, and in the case of a 4x6 system, it would take about 27 minutes to trip out 250 feet of 4.5-in. rod.”
The SDT60 system is extremely versatile since the weighted wireline option and the 2.25-in. center rods can be used at any point in the boring. The 6-in. casing doesn’t have to be pulled, and drilling can proceed with whichever system (WWL or 2.25-in. center rods) the driller thinks is best for his drilling conditions – he can switch back and forth, if needed, depending on the drilling conditions.
According to Jed, the test project was a success. “The tooling system performed flawlessly, and with just a few points of direction, the Enviroprobe Services crew was able to take over and operate this new tooling system on their own with confidence,” he said. “It was great to see how well they adapted to it. Everyone at the site was great to work with.”
The WWL option for the SDT60 makes a great addition to an already efficient sampling system. The use of the 2.25-in. center rods in the shallower, unconsolidated formation coupled with the WWL at the deeper, more consolidated formations was a great match for this project.