An investigation of a highway project revealed a sandstone formation with steeply dipping bedding into the face. Many weak joints were identified. An analysis of the plan and profile sheets, and the cross sections, showed that the average bench height will be about 15 ft. Bulk ANFO, specific gravity 0.8, and primer, specific gravity 1.3, will be the explosives used on the project.
The primer comes in 8-in.-Iong X 1~ in.-diameter sticks. The contractors equipment can easily drill6-in.- diameter holes. It is assumed that delayed initiation will be utilized.
a. Develop a blast design for the project.
b. If the burden distance is held constant at 5 ft, but the hole spacing is varied in 1-ft increments across the range of S developed in part (a), what is the cost per cubic of rock if the ANFO is $0.166 per Ib, and dynamite $1.272 per lb?