EnviroProbe Integrated Solutions Inc. in Nitro, W.Va., completed an environmental site assessment (ESA) using both drilling and direct-push applications. The results of the ESA indicated the need for installation of permanent ground water monitoring wells on the residential property to depths of 85 feet. A previous drilling company was unsuccessful in setting the wells using hollow-stem auger methods, primarily due to the heaving/flowing sands in the subsurface. The EnviroProbe field team, with a Geoprobe 8040DT combo rig, completed the ESA work with no problems.
At a later date, EnviroProbe used its 8040DT rig to install two 2-inch prepacked screen monitoring wells, each to a depth of 85 feet using the direct-push feature of the rig. For the process, the field team used DT45 tooling to collect continuous soil samples. A 6-inch-diameter cutting shoe with expendable knock-out was used to allow for the installation of the 2-inch monitoring wells that meet the minimum borehole diameter for a 2-inch well. Once at depth, the field team knocked out the expendable shoe, and installed the PVC well through the DT45 casing. As the rods were extracted, Dale Kestner, EnviroProbe’s driller, installed additional filter sand, a bentonite filter pack seal, and annulus space seal.
“Our 8040DT rig continues to perform for us,” says Rod Moore, EnviroProbe’s owner. “The advantages of owning and using this rig make our jobs easier. It allows us to complete a wide-range of jobs with just one rig.”
Moore lists several reasons for the success of this project – time, cuttings, subsurface conditions, safety and cross contamination.
In approximately six hours, En-viroProbe set up, collected two soil borings (continuous dual-tube soil sampling), set two two-inch PVC wells to 85 feet, and cleaned up the site. Using the standard methodology (hollow-stem auger and continuous standard penetration test sampling), this project would have required a three-man drill crew and approximately two days to three days to complete, while causing damage to the residential yard. “Our method saved our client a minimum of $2,500, and one-to-two days field time,” Moore says.
EnviroProbe produced less than one drum of soil cuttings during the ESA. Normal hollow-stem auger drilling probably would have produced a minimum of eight to 10 55-gallon drums of cuttings, which would have required disposal. “This also saved our client at least $2,500 in transport and disposal costs,” Moore adds.
EnviroProbe’s system eliminated the heaving or flowing of sands into the rod string. “Prior to our arrival onsite,” Moore explains, “the hollow-stem auger method caused significant heaving/flowing sands through the liquefaction and mixing of the sandy saturated zone.”
Using the direct-push feature of the rig and the DT45 tooling, the field team avoided the need for rotary drilling, eliminating the risk associated with turning augers.
Hollow-stem auger methods typically will promote drag-down (cross-contamination) of shallower contaminants into the subsurface and ground water. The ability to push/hammer the casing eliminates the effects of drag-down.
“Sometimes we wonder whether the job will be too much for our rig, but it continues to do a great job for us,” beams Moore. “We’re especially pleased with the power this rig has. It hasn’t disappointed us yet.” ND
