Drilling Method No. 3: Heading same as second method, but larger lift taken off bench, and lift holes drilled in bottom bench in order to get down to grade in floor. Bench kept closer to heading. +---------------------------------------------------------+ | Per Round | +---------+------------+-----------+------------+---------+ | | Total | No. of | Pounds | | | | Depth | Cubic | of | Advance | | | Drilled | Yards | Dynamite | | +---------+------------+-----------+------------+---------+ | Heading | 190 to 220 | 35 to 42 | 134 to 196 | 6½ to 8 | +---------+------------+-----------+------------+---------+ | | | | | | | Bench | 145 ” 190 | 90 to 110 | 118 ” 167 | 6½ ” 8 | +---------+------------+-----------+------------+---------+ +-----+-------------------------+----------------------------------+ | | Per Cubic Yard | Per linear Foot of Tunnel | | +------------+------------+-------+-----------+--------------+ | | Linear | Pounds | Cubic | No. of | Pounds | | | Feet | of | Yards | Feet | of | | | Drilled | Dynamite | | Drilled | Dynamite | +-----+------------+------------+-------+-----------+--------------+ | Hd. | 5.4 to 6.0 | 3.9 to 5.0 | 5.3 | 28 to 32 | 20.7 to 26.5 | +-----+------------+------------+-------+-----------+--------------+ | B. | 1.6 ” 1.9 | 1.3 ” 1.8 | 13.7 | 22 ” 36 | 17.8 ” 24.7 | +-----+------------+------------+-------+-----------+--------------+ | Total | 19 | 50 ” 58 | 38.5 ” 51.2 | +-------------------------------+-------+-----------+--------------+ | Per cubic yard, whole tunnel section | 2.6 ” 3.1 | 2.0 ” 2.6 | +---------------------------------------+-----------+--------------+