4.2 Drilling and logging
The spacing between drill holes is approximately 3.6 kilometres. The drill hole spacing is supported by both geological considerations and aligned with
Saskatchewan Potash industry practices (Figure 7).
All drill holes were vertical, considered by the Competent Persons as appropriated for the horizontal,
gentle dipping potash horizons.
The drilling method used for both the historical and BHP acquired drill holes employed standard petroleum industry rotary
drilling and coring techniques in full compliance with Saskatchewan drilling regulations and industry standards. Continuous rotary coring, that provided approximately 8.5 centimetre diameter core, was used from the Dawson Bay Formation through the
potash beds of the Prairie Evaporite Formation to obtain subsurface samples. The overall core recovery was approximately 100 per cent with no core recovery less than 99 per cent.
Core from BHP drill holes were geologically logged to identify the potash and interbedded clay seams, supported with downhole geophysical logs. Photographs
were taken of the whole core and cut core prepared for analysis.
A quarter sample of all core is provided to the Saskatchewan Subsurface Geological
Laboratory for storage and public access, this includes the historic and BHP drill holes.
4.3 Surveys
All surveys for the project are referenced to coordinate system of Universal Transverse Mercator Zone 13N and North American Datum 1983 (UTM NAD83 Zone 13N).
The survey data was acquired by certified surveyors.
Surface topography was mapped using aerial surveying techniques with one metre horizontal and 0.5
metre vertical accuracy.
Downhole deviation of BHPs drill holes was measured with a petroleum industry standard deviation tool based on the
magnetic method. Historical drill hole collars were surveyed using terrestrial based techniques and the drill holes are assumed to be vertical. Based on the nature of the deep drilling, and BHPs Saskatchewan drilling experience, it was
concluded that the possible historical drill hole deviation would not be significant and there is no impact on the measured mineralization thickness.
Seismic data, shot and receiver points, and BHP drill hole collars were surveyed using Real Time Kinematic or Post-Processed Kinematic Global Positioning
System surveys. The approximate accuracy of these surveys is 0.5 metres horizontally and vertically.
4.4 Sampling and analytical procedures
Historical drilling (1952-1965) contributed 1,170 samples with variable sampling interval thicknesses to the exploration data set. Historical drill hole
samples collected by Kerr-McGee Corporation were processed in their internal laboratory (Kerr-McGee Research Laboratory) by titration method.
During
BHPs drilling campaign (2008, 2009) 3,956 samples were collected. The length of the samples was variable (average sample length 15 centimetres) to capture key geological features. The sampling was continuous through the UPL, LPL, and BP potash
sub-members. The drill hole core was split, with one quarter of the sample used for geochemical analysis, half was used for metallurgical testing, and one quarter submitted to the Saskatchewan Subsurface Geological Laboratory for archival.
Sampling protocols and procedures are aligned with industry standard practices. The sample preparation protocols (crushing and pulverising sizing
requirements, etc.) at laboratories meet standards defined in contracts in line with ISO standards, with QAQC targets established. Saskatchewan Research Council Analytical laboratory analysed all the geochemical samples using the Inductively Coupled
Plasma Optical Emission Spectroscopy (ICP-OES) method. Metallurgical testing of all metallurgical samples was conducted in SGS Lakefield Ltd. laboratory. Both laboratories are ISO/IEC 17025 certified.
4.5 Quality of assay data and laboratory tests
BHP potash has
defined a program to ensure an appropriate level of confidence in the accuracy and the precision of the geochemical data derived core samples. This program includes standards, blanks and duplicates.
BHP standards were inserted to check the accuracy and precision of the laboratory in addition to the internal standards inserted by the laboratory as part of
their own QAQC program. Blanks were inserted to check for cross contamination during the pulverization and analytical stages and as a check on analytical precision and accuracy. Site duplicates are included to test representativity of taking a split
of the coarsely crushed drill core for the analytical work. BHP inserted laboratory duplicates and the contract laboratory inserted repeat duplicates to test laboratory precision (reproducibility) of the various analyses performed.
All the BHP control samples were inserted hidden to the laboratory as a standard industry practice.
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