FOOT WALL PHASE 7

NTER-REMP SLOPE + 45 0*

FIGURE 2 — Section showing current design paramters.

be optimized by the time mining to ultimate pit limits
(final phase) is started. Current operating slope de-
signs are graphically documented on an idealized sec-
tion (Fig. 2) and are summarized as follows:

FOOTWALL:
Inter-ramp slope.................. 37° (toe to toe)
Inter-berm slope.................. 66° (crest to toe)
Bermiwidthis pet ryt acts a seen 53 ft (16.1 m)
BermiinterValices cc. e-5- cians ate 60 ft (18.3 m) (double benching)
Benchiheights =. sae cee ese 30 ft (9.1 m)

HANGING WALL:
Ore and Waste Serpentine

Inter-ramp slope.................. 40° (toe to toe)

Inter-berm slope.................. 66° (crest to toe)

IA WAGs 5+ se sakasodesokec cee] 45 ft (13.7 m)
Bermiumntenvalienesst. ne recvre ce 60 ft (18.3 m) (double benching)
Benchsheightassmses eet ee 30 ft (9.1 m)

Argillite from Serpentine/Argillite Contact to 180 ft (54.9 m) Above
Contact

Inter-ramp slope.................. 47° (toe to toe)

Inter-berm slope.................. 66° (crest to toe)

Berm widthteecnspetg-pesneesesmalre res 44 ft (13.4 m)
Berimbintervalbeeentasseetaaerrcnmr 90 ft (27.4 m) (double benching)
Benchiheighteeenese eee eeer rae 45 ft (13.7 m)

Cassiar personnel map out strategy.

66

PHASE 8

7 NTER-RAMP SLOPE + SOO"

CASSIAR ASBESTOS CORPORATION LIMITED

PHASE 9 sad bet” Sos
NTER-RAMP SLOPE « DIAGRAMMATIC SECTION SHOWING

a CURRENT DESIGN PARAMETERS

Bae Tee [eareas ean

Argillite Greater than 180 ft (54.9 m) Above Serpentine/Argillite
Contact

Inter-ramp slope.................. 50° (toe to toe)

Inter-berm slope.................. 66° (crest to toe)

Bermiwidths seen sacar eee 35 ft (10.7 m)

Berm interval.....................90 ft (27.4 m) (double benching)
Benchiheight: 2)\ S202 c-an ee sen 45 ft (13.7 m)

The above slope parameters have evolved through
field trials and structural analyses by several con-
sulting firms.

The need for optimizing pit geometry was apparent
in 1971 when deep diamond drilling extended the depth
of the orebody. In early 1972, the argillite portion of
the Phase 7 hanging wall was steepened to a 49-degree
inter-ramp slope, based on a pre-splitting design. A
shortage of drilling capacity, combined with prominent
jointing, negated the effectiveness of pre-splitting.
Accordingly, the argillite portion of the hanging wall
was redesigned at a 45-degree inter-ramp slope until
structural data could be accumulated and evaluated.
In 1974, a slab failure occurred on the footwall haulage
road, because the ramp straddled the faulted serpen-
tine-argillite contact. Drilling during 1973 and 1974
also indicated a roll or bulge of the contact into the
footwall at depth. Consequently, it was apparent that
the ultimate footwall haulage road system must be
relocated behind the footwall serpentine/argillite
contact.

Initial evaluation indicated that a 47-degree inter-
ramp was feasible and a contractor was brought in to
start the excavation in the fall of 1974. However,
mining revealed a more complex sructural system than
anticipated and an abundance of highly unstable
graphitic material was encountered which eventually
required the redesign to the present inter-ramp slope
angle at 37 degrees.

_As shown, the inter-berm slope for all zones is 66
degrees. This figure was initiated as a function of
shovel digging are to provide a base for experimenta-
tion with the objective of evolving the steepest possible
inter-berm slopes on a cost/benefit basis, thereby

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