4c. Croplining

Croplining is a process geologists use to determine the edge boundary of mineable coal. The edge of mineable coal is called the cropline. Without croplining, the drillers might uncover a pit with no coal.

Croplining Process

1. Using information from the initial samples, a geologist creates an estimated cropline.
2. Along the estimated cropline, drillers dig 25-foot deep overburden holes with traverses every 300 feet. The traverses are the lines to start drilling. 
3. Then, the miners drill perpendicular rotary holes every 100 feet because coal pits are on average of 175 feet wide. 
4. A geological engineer analyzes the samples and creates an adjusted cropline.