REP39823

• Permit No: M1973021
• IBM Index Class Name: Report
• Doc Date: 3/3/2006
• Doc Name: Geotechnical Addendum for 2005 Annual Report
• From: Aggregate Industries
• To: DMG
• Permit Index Doc Type: Stability Report
• Media Type: D
• Archive: No

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sets of anticline/syncline structural features in the rock mass. The primary joint set coincides
with foliation of the rock mass. In general, the foliation dips in a southwest direction. Foliation
orientation has local variations due to several sets of localized anticline/syncline structural
features in the rock mass and may dip out of the highwall in localized areas. Dip angle varies
from approximately 10 degrees to 53 degrees. Mapping data is provided in Table 1. Spacing of
joints in the primaryjoint set typically ranges from 0.5 ft to 2 ft. Joint surfaces are typically
tight and appear slightly weathered to moderately weathered. Joints are very continuous in
certain locations, and discontinuous in other locations.
The secondary joint sets on the north exposure Benches (B and C) are the same in bearing and
dip as the secondary joint sets previously described for the west exposure Benches (1, A, B, and
C).
In addition to the joints, three larger scale features were observed as described below:
Shear -this feature is seen along the ease central end of the northem exposure
of the North Quarry. It extends from the current quarry floor (Bench C) to the
ridge line (Bench 5) for a vertical distance of approximately 280 ft. On
Benches A and B it was measured for the 2004 Addenda to strike with a
bearing of N 20 E to N 30 E and dip was variable from 40 to 80 degrees to the
west. This feature becomes difficult to see on Bench C, but is assumed to
continue through to Bench C. With this orientation it strikes approximately
perpendicular to the highwall and dips parallel with the highwall. The shear
zone is 3 to 4 ft thick and composed primarily of crushed rock. Due to the
orientation of this feature relative to the highwall, it is not expected to present a
high level of risk for large scale slope instabilities. Localized instabilities,
especially at the outside edge of each bench are expected however.
2. Seam -this feature is seen along the central portion of the northern exposure of
the North Quarry on Benches A (previously mapped for 2004 Addenda) and B.
It was measured to strike with a bearing of N 25 W to N 35 W and dip was
variable from 19 degrees to 35 degrees southwest. With this orientation is
strikes sub-perpendicular to the highwall and has a small component of the dip
out of the face. The seam is 3 inches to 9 inches thick with some red clay
infilling 1 to 2 inches thick. This feature is exposed on Bench B from station
5+15 to 6+28. The seam is a potential historic slip plane. Different rock types
were observed above and below the plane. The rock above the plane was
observed to be much more weathered than below the plane indicating a
possibility of historic movement along the plane. Due to the orientation of this
feature relative to the highwall and the relatively shallow dip angle, the
component of the dip out of the highwall is small and it is not expected to
present a high level of risk for large scale slope instabilities. The potential for
small scale block failures exists at the upper end (east end) of the seam at the
top of Bench B where it crosses into the bottom of Bench A
3. Adversely Dipping Foliation -this condition is seen in the northwest corner of
Benches 1, A, and B. There is an area of gray colored moderately weathered
rock in which the foliation is dipping out of the highwall. The feature is big
enough to potentially produce localized wedge failures. However, the failures
would not be expected to extend beyond the limits of the individual benches.
The overall north slope appears stable. Localized instabilities are limited to single benches and
are evidenced by relatively small block and wedge shaped slip surfaces and raveling, generally