REP34730

• Permit No: M1973021
• IBM Index Class Name: Report
• Doc Date: 3/24/2000
• Doc Name: ANNUAL REPORT
• Permit Index Doc Type: ANNUAL FEE / REPORT
• Media Type: D
• Archive: No

' Some foliation dip angles are as shallow as 20 degrees in the new final highwalls
created in 1998. However, the strike is generally sub-perpendicular and has a
' relatively more favorable orientation for stability, except on the northern portion of
the highwall of Bench 2, where the foliation strike joints are almost parallel to the
slope
' At least two secondary joint sets are present, often orthogonal with the primary joint
set and to each other. These secondary joints typically occur at intervals of one to five
ft and are typically moderately to steeply dipping. These joints occasionally daylight,
' causing localized block and wedge failures within acceptable limits. In general,
secondary joint surfaces are planar and are less weathered than the primary joints
along foliation. They do not exhibit the smooth schistose or micaceous surfaces.
These secondary joints are also usually discontinuous, terminating a[ primary joints.
Slope failures are limited to infrequent and relatively small block and wedge failures,
' generally less than 10 feet in length. These types of failures are as expected for the
highwall and only cause localized operational inconveniences.

1
1

1

1
Based on the rock mass conditions observed, the conditions of the rock mass of the
new final highwalls developed during 1998 are consistent with the conditions used as
the baseline for analyses of the east side.
The previously unstable slope and the resulting mitigation design on Bench 7 and 6
had no observed problems
B. Survey
Twenty-six surface survey points (numbered 2001 through 2026) were established to
monitor the effectiveness of the repair of the unstable slope on Bench 6 and 7.
Positions of the surface survey points have been determined by surveys conducted in
March and May 1997, March 1998, and August 1998, which provide data to assess
the performance of the slide repair during 1998. Several survey points have been
damaged by mining activities. All the remaining points exhibited less than 0.12 ft of
displacement from March [o August 1998, indicating stable slope conditions.
Points 2002, 2003, and 2004 were stable in 1998. These points had exhibited
movement during 1997 due to local sloughing of the shallow soil and weathered rock
near ground surface.
5.03 South Eud of Central Quarry
At the south end of the Central Quarry, the rock mass is typically poor. The rock mass
structure is highly fractured and contorted with inconsistentjointing patterns. The primary
joint set is foliation joints in gneiss and schist rock. Foliation joint dip orientation varies as
does the strike, but is generally southerly and into (or less frequently westerly and parallel [o)
the slope orientation. Joint spacings typically range from several inches to approximately 5
ft. Joint surfaces vary greatly from fresh to highly-weathered. Weathered schist interbeds
having a slick and weak character are frequent throughout the rock mass, and talc-like
alteration is prevalent in this portion of the quarry.
' G~~PROIECI'S~10300.NOrn»n Quury~002\A,uwY Rq,nn GcolaMKal A6dc,MUm~l9Y8\98ry~ nrukup.tloc Page 7