Major Drilling Environmental LLC (MDE), headquartered in Moncton, New Brunswick, recently completed a deep, rotary sonic geotechnical boring to a total depth of 180 feet within the Troutdale Formation. The Northwest’s Troutdale Formation is an alluvial sand and gravel deposit, characterized by cemented gravels, cobbles and Volkswagen-sized boulders. In order to penetrate this difficult formation for collection of geotechnical soil samples, MDE mobilized one of its seven Geoprobe 8140 Rotary Sonic track rigs to complete this work.
Recently, MDE was selected to participate in a geotechnical subsurface investigation consisting of mud rotary borings, cone penetration testing advancement, and one rotary sonic boring in support of a geotechnical engineering assessment and design for a new regional transportation bridge in Portland, Ore.
The field team collected continuous 4-inch-diameter soil cores to a total depth of 180 feet below ground surface, utilizing MDE’s proprietary sonic tooling. A temporary 8-inch-diameter conductor casing was installed to 25 feet, and the borehole was advanced to 180 feet using 6-inch-diameter casing and a 4-inch-diameter core barrel.
The challenge of the Troutdale Formation drilling was further complicated by soft ground conditions (several feet of mud) and Northwest rain showers, coupled with the environmental site concern of asbestos-containing materials (ACM) in the near surface soils. All members of MDE’s experienced drill team are asbestos-awareness trained, and the work area was continuously air-monitored for ACM. The combined maneuverability and power of the rotary sonic (long-stroke) rig, and MDE’s highly trained sonic drilling operators were a great match in getting the project completed on time with accurate results.
According to Steve Zimmerman, MDE’s on-site sonic operator, the Troutdale Formation threw challenges at the crew at every turn. “The penetration rate began to slow down at around 120 feet due to cemented gravels,” Zimmerman explains. “But the 8140LS kept going slow and steady.” The rubber-tracked sonic rig enabled site access, and the sonic power of the Geoprobe-designed GV4 sonic head helped ensure successful completion of the Troutdale Formation boring.”
MDE is a full-service contract drilling and sampling company that serves markets across the United States. The company specializes in drilling for environmental, geotechnical, geothermal, aggregates and construction, clean water, and mining applications. Currently, MDE is operating a new fleet of seven Geoprobe rotary sonic rigs, including 8140LS, 8140DT, and the all-new limited-overhead-access 8140LC, which can work under a 13-foot clearance.