Lesson 1/Learning Event 2
First convert the depth of the face to yards:
30 feet
=
10 yards.
3 feet/yard
Then enter the values into the equations:
Qt
=
depth x working area
Qp
= Qt[l - (W/100)]
Qt
=
10 yds x 90,000 sq yds
=
900,000 CY of rock (bank)
Qp
=
900,000 CY x [1 - (10/100)]
=
900,000 CY x (0.9)
=
810,000 CY of usable rock (bank).
From Table 3, you find that one CY of average bank rock yields 1.7 CY of loose rock.
1.7 loose CY x 810,000 bank CY = 1,377,000 loose CY.
Therefore, your quarry should yield 1,377,000 loose CY of usable product.
TABLE 3. WEIGHT-VOLUME RELATIONSHIPS
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