2010-12-17_REVISION - C1981019 (130)

Home Browse Search

EXECUTIVE SUMMARY Project Focus At KEC Colowyo Coal Company's (CCC) request, Rio Tinto Technical Services (TS) visited CCC during the period 14 -24 March 2005, in order to review the status of the geological databases and associated data. This review was required to ensure the veracity of the data used in the geological model update, and resource and reserve calculations. Approach TS used a series of Excel spreadsheets to review the data from the all the drilling data in the database. Information was derived from drilling programmes completed by KEC as well as campaigns by Grace and Utah. TS also reviewed the QA/QC Procedures and the Geological Model. Major Findings Significant amounts of work have been completed to update the drill hole database. Many procedures are in place and are being followed. Procedures identify seams >2 ft thick for sampling. CCC mines seams <2 ft. Following a brief review of the CCC geological database TS considers that the majority of data in the Collom database are sufficiently reliable to be used for resource estimation purposes. • The Apparent Specific Gravity (ASG) data show scatter. Some of the historic drill holes have been included in the database. • Seam correlations have been standardised across and beyond the Collom lease areas. • Original data are stored in a secure location in good order. Access database integrity is good. Only the database manager has delete rights and users have data entry and edits rights. • There are good and improving data validation processes in place. • CCC does not have written data entry/transfer procedures for its drill hole database. CCC does not have documented procedures for use when archiving or exporting data from its Geological model. Visualisation of seam surfaces in the geological modelling software, MineScape, indicates that a drill hole intersection is not necessarily honoured by the surface. RIO TINTO BR3273: FINAL Version: 1 i T e ,h n"" l51e "i -,