Abstract: An Evaluation of the Minimum Required Sampling Density of Middle Pennsylvanian Interburdens at a Typical Southern West Virginia Surface Mine; A Preliminary Study

Thomas P. Cook, John J. Renton, Ronald R. McDowell, Michael Ed. Hohn

The goal of this project is to establish the minimum sampling density required to accurately characterize a volume of Middle Pennsylvanian interburden. This project is significant to the coal industry of West Virginia in that it will allow mining operators to more precisely predict acid mine drainage (AMD) potential of interburdens and overburdens.

The field area for this project is located at an active surface mine in southern West Virginia. Samples were collected from air rotary drill cuttings during the drilling of shot holes. Representative samples were taken of continuous 1.2 m (4 ft.) intervals down each drill hole. Three analyses were performed on all samples: Total percent sulfur by total combustion, X-ray diffractometry, and elemental analysis by X-ray fluorescence. The known elements and minerals that have the greatest effect on AMD were used in the interpretations. Those elements and minerals are total percents of: sulfur, calcite, pyrite, siderite, calcium oxide, and ferric oxide.

Through the use of a FORTRAN program called PIKSAMP4, holes were randomly excluded from the data sets. This was systematically done in one-hole intervals starting with the complete data set and continuing until only one hole remained. The process of excluding individual holes was repeated a minimum of one hundred times for each data set. The mean, standard deviation and coefficient of variation were calculated for each chemical parameter as sample density varied. These graphs were then interpreted to determine how many data points (holes) were required to accurately predict the AMD potential of the sample site.

AAPG Search and Discovery Article #90950©1996 AAPG GCAGS 46th Annual Meeting, San Antonio, Texas