Drilling
PPML completed definition drilling H1 2024, with the overall objective of reducing the drill intercept spacing to approximately 30 metres to qualify the majority of the mineral resource base as Indicated Mineral Resources. To minimize the impact on the environment and forest floor, drilling in wetter areas was mostly conducted in winter under frozen conditions.
Database
Since taking over the project in 2018, PPML has recovered some 20,000 historical drillholes into a modern and highly functional database. This work includes positioning the dataset using Differential GPS (DGPS) based on drill collars identified in the field. Furthermore, the entire dataset has been registered to elevation control using DGPS and a hyper-accurate LiDAR survey conducted over the property area.
Core from approximately 800 historical Cominco drill holes were recovered, re-logged, and re-assayed as the lower grade historical holes were not assayed if the deposit did not have the potential to grade greater than 10% Zn+Pb. This was the average grade during their production period, and almost twice the grade of the 2024 MRE.
Data and data modelling
An extensive GIS database using MapInfo-Discover™ is combined with GEMS™ and Geoscience Analyst Pro™ to manage and interpret data daily and as programs evolve with new incoming data and interpreted results. Drill hole data, geology, mineralization boundaries, pit wall mapping, geophysics, LiDAR, and historical open pit mine bathymetry have been combined in GoCAD™ software along with the detailed interpretation of some 3800 vertical drill sections to produce a robust and dynamic 3D model for the entire project.
Recent structural analyses of all available open pits, combined with 3D drone photography of pit walls was carried out by Terrane Geosciences in 2021. This allowed for the construction of initial structural geology models that are now added to the 3D model to locate specific structural features within areas of the future mine plan. This model supports and greatly enhances mine design, hydrogeological modelling, as well as exploration targeting.