8
alignment. The second step is to align a reasonable and
pragmatic operating plan with the goals of the project,
which in the case of Cleveland-Cliffs and Hibbing Taconite
Company that goal is to operate an exceedingly safe tail-
ings storage facility. To give the scale of shift that the down-
stream improvements inclusion into the operating plan
presented is shown in Table 3 and Figure 6. As illustrated in
the 2019 operating plan in Figure 6 the years 2020 to 2024
swelled by two to three times the 2018 operating plan. At
Hibbing Taconite Company, the main dam construction
materials are the coarse tailings (a well-graded sandy soil),
which is well-suited for an impounding fine tailings, so the
main constraint on construction rates was the supply of
coarse tailings. The introduction of this paper notes that
Hibbing Taconite Company produced approximately 18
million tons of tailings in 2022 of which 7.2 million tons
are the coarse fraction. Of that 7.2 million tons, not all are
available for dam construction, so the 2019 operating plan
fit to that availability and what was logistically probable to
be able to complete each year.
Table 4 compares the fill volumes required needed for
downstream improvements based on the revised dam sta-
bility analysis using the initial conservative assumption of
0.05 for an undrained shear strength ratio for liquefaction
used in 2019 planning and design. The significant variation
Table 3. Hibbing Taconite Company Tailings Facility—2018 Operating Plan comparison to the 2019 Operating Plan
Figure 6. Hibbing Taconite Company Tailings Facility Operating Plan Comparison
Table 4. Hibbing Taconite Company Tailings Facility—
Downstream Improvement Embankment Volume compared
to Undrained Shear Strength Ratio for Liquefaction
Undrained Shear Strength Ratio for
Liquefaction
0.05 0.08 0.11
2019 Downstream Embankment
Volume Estimate (MCY)
13.3 7.8 4.6
alignment. The second step is to align a reasonable and
pragmatic operating plan with the goals of the project,
which in the case of Cleveland-Cliffs and Hibbing Taconite
Company that goal is to operate an exceedingly safe tail-
ings storage facility. To give the scale of shift that the down-
stream improvements inclusion into the operating plan
presented is shown in Table 3 and Figure 6. As illustrated in
the 2019 operating plan in Figure 6 the years 2020 to 2024
swelled by two to three times the 2018 operating plan. At
Hibbing Taconite Company, the main dam construction
materials are the coarse tailings (a well-graded sandy soil),
which is well-suited for an impounding fine tailings, so the
main constraint on construction rates was the supply of
coarse tailings. The introduction of this paper notes that
Hibbing Taconite Company produced approximately 18
million tons of tailings in 2022 of which 7.2 million tons
are the coarse fraction. Of that 7.2 million tons, not all are
available for dam construction, so the 2019 operating plan
fit to that availability and what was logistically probable to
be able to complete each year.
Table 4 compares the fill volumes required needed for
downstream improvements based on the revised dam sta-
bility analysis using the initial conservative assumption of
0.05 for an undrained shear strength ratio for liquefaction
used in 2019 planning and design. The significant variation
Table 3. Hibbing Taconite Company Tailings Facility—2018 Operating Plan comparison to the 2019 Operating Plan
Figure 6. Hibbing Taconite Company Tailings Facility Operating Plan Comparison
Table 4. Hibbing Taconite Company Tailings Facility—
Downstream Improvement Embankment Volume compared
to Undrained Shear Strength Ratio for Liquefaction
Undrained Shear Strength Ratio for
Liquefaction
0.05 0.08 0.11
2019 Downstream Embankment
Volume Estimate (MCY)
13.3 7.8 4.6