Mine Tailings In Northern BC
Purpose: Geotechnical investigation for mine tailings facility
Location: Houston, BC
Gregg in support of its partner company Geotech Drilling Groupm completed a CPT and drilling investigation at a closed tailings storage facility at large mine, near Houston, BC.
The work included almost 600 m of drilling, sampling, and CPT testing (ASTM Standard D5778-12) using a Gregg skid-mounted B-53 drill and independent 2-ram, 20-ton CPT ramset carried aboard Gregg’s purpose-built sectional drill barge. The highly portable spud barge is capable of carrying all the drill rigs in our fleet and provided our crews safe and controlled access to drill sites throughout the challenging shallow water tailings environment. Work consisted of Cone Penetration Testing (CPT) (ASTM D5778-12), submarine seismic CPT data collection, cased mud-rotary drilling, split-spoon sampling, and hydraulic piston sampling in water depths ranging from 2 m to 9 m deep; and test depths from 5 m to 38 m below mudline. Total drilling and testing was nearly 600 m combined across 30 sites.
Further to the tailing pond work, Geotech Group’s sonic team also completed a land based program. This included 8 boreholes advanced by 4×6″ sonic drilling with 7″ override casing totaling 221m of drilling, and 6 SPT’s in three holes. Of these holes, 2 were installed with 2″ PVC monitoring wells, 5 holes installed with VWP’s and all holes grouted to surface.
Through the late fall and early winter weather, the crews faced challenges with changing conditions. With a strong behaviour-based HSE culture and solid work plan in hand, they completed the project safely, on schedule and within budget. Planning for success led to a safely executed project.
Mine Tailings In Central BC
Purpose: Geotechnical investigation for mine tailings facility
Location: Kamloops, BC
Gregg completed a geotechnical investigation program that included sCPT, CPT, in-situ vane, disturbed sampling and undisturbed sampling of soft tailings and beach deposits in 2017. Throughout the program Gregg provided an amphibious work platform in the tailings pond to support a CPT workstation during CPT testing and a B53 skid rig to perform sampling and vane testing scopes of work. The amphibious work platform allowed for easy access throughout the varying shallow water depths throughout the active facility. Drilling methods included wet rotary techniques to advance samplers to collect soft soils with low strengths. Vane testing was conducted using electronic digital controlled down-hole vane testing that resolved peak and residual soil strengths on the order of 2 to 3 kPa. The program utilized the assistance of shore-based winches to maintain worker safety and machine mobility.
Hole depths have ranged from 10m to 40m in water depths ranging from 0m to about 3m. Shelby tubes, piston sampling, vane shears, CPTs and SPTs were conducted throughout the program. CPTu production exceeded over 100 m/shift during some periods of high mobility with crews operating 12 hours a day. Continuous piston tube sampling was carried out with consistent full recovery.
Throughout the program the crew dealt with challenging factors including working in an active mine environment, inclement weather, working closely to existing infrastructure around and below the facility as well as multiple contractors and support. Production estimates were consistent with the original proposed work plan.
LNG Facility in Northwest BC
Purpose: Geotechnical investigation for potential LNG facility
Location: Prince Rupert, BC
Gregg/ Geotech completed an offshore geotechnical investigation program in 2016. Throughout the program Gregg/ Geotech provided 1 Fraste MDXL drill rig, with ancillary equipment, completing mud rotary drilling with a casing advancer system. The program utilized the assistance of ocean barges for drilling platforms throughout the program.
Hole depths have ranged from 13m to 45m in water depths ranging from 6m to 30m. Shelby tubes, piston sampling, vane shears, CPTs and SPTs were conducted throughout the program. Production exceeded up to 170 ft during some periods with crews operating 24 hours a day.
Throughout the program the crew dealt with challenging factors including; tides, weather, working closely to existing infrastructure and the shore, variable mud line and ground conditions and operating 24hrs a day. Although these challenges were faced the crews completed the program early and under budget.
LNG Facility in Northwest BC
Purpose: Geotechnical investigation for facility
Location: Prince Rupert, BC
Gregg/ Geotech participated on a nearshore geotechnical investigation program throughout 2015 and 2016.
Throughout the program Gregg/Geotech provided 2 Fraste MDXL drill rigs, with ancillary equipment, completing an array of methodologies including; CPT, mud rotary and rock coring. The program utilized the assistance of ocean barges for drilling platforms throughout the program.
Work consisted of geotechnical boreholes to maximum depths of approximately 150 meters below seabed. Seismic Cone Penetration Testing (SCPT) was also completed to maximum depths exceeding 50 meters below seabed. Multiple platforms/vessels were used concurrently to complete the project scope of work (assets included dedicated drillship R/V Quin Delta, two (2) 4-point anchor barges with tracked drilling equipment and a dedicated seabed CPT unit.
Gregg/ Geotech completed the offshore portion of the program utilizing a floating barge with mud anchors; where Gregg/ Geotech overcame the challenges of the extreme currents and tides. Other challenges overcame throughout the program include; weather, changes in stratigraphy and protesters from the community.
Tailings Drainage Project
Purpose: Amphibious trenching in tailings to accelerate dewatering. Use of winch-assisted amphibious vehicle recovery system.
Location: Fort McMurray, Alberta
Two programs were undertaken to test the use of an amphibious trenching unit to cut shallow trenches in tailings to accelerate the dewatering process. Over 10 different tailings cells of varying age and settlement characteristics were modified by using a dual-disc rotating Donde ditcher attached by Gregg to the rear of an Amphibious Carrier. The work was undertaken in 2 phases; a Summer Program in July and August 2015, and a Winter Program in February 2016. All program objectives were met and, in addition to the trenching work, Gregg successfully developed and operated a winch retrieval system utilizing light-weight but high-strength Dyneema fiber rope to pull the amphibious unit out of very soft tailings up to 1.5 km from the winch unit.
Throughout the program the crew dealt with challenging factors including; weather, working closely to existing infrastructure and mining equipment, variable tailings characteristics, and stringent safety and operational controls. Although these challenges were faced, the crews completed the program early and under budget.
