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buttress was removed. <br /> ' Haley & Aldrich and CAMAS proposed and DMG approved <br /> changing the mining limits, but not the permitted acreage, as a <br /> Technical Revision(TR) to the permit. CAMAS agreed to <br /> monitoring the slope via survey to confirm stability. Finally, it was <br /> agreed that additional special reporting and DMG staff review of <br /> stability evaluations need not occur prior to TR approval, but rather <br /> could be handled on an annual basis as part of the already required <br /> Annual Report geotechnical updates such as this report addendum. <br /> ' 5.3 South End of Central Quarry <br /> A. The parent rock material is typically weak and is estimated to have an <br /> ' unconfined strength less than 15,000 psi. <br /> B. The rock mass structure is highly fractured and contorted with little consistent <br /> ' jointing pattern. The primary joint set is along foliation of the gneiss and <br /> schist rock. Foliation joint dip orientation varies as does the strike, but is <br /> generally southerly and into, or less frequently westerly and parallel to the <br /> ' slope orientation. Joint spacings typically range from several inches to <br /> approximately five ft. Joint surfaces vary greatly from fresh to highly- <br /> weathered. Weathered schist interbeds having a slick and weak character are <br /> ' frequent throughout the rock mass. Talc-like alteration is prevalent in this <br /> portion of the quarry. <br /> C. At least two secondary joint sets are present, generally orthogonal to the <br /> primary joint set. In some cases, they cut through primary jointing and in <br /> some cases they terminate at a primary joint. These secondary joints typically <br /> ' occur at intervals of one to five ft. In general, secondary joint surfaces are <br /> fresher and less-weathered than the primary joints along foliation and do not <br /> typically exhibit the smooth schist or mica surfaces. <br /> Based on the conditions observed with the present exposures, the rock mass at <br /> the south end of the Central Quarry is tentatively classified as "poor" in terms <br /> of the previously-established baseline conditions. The term rock mass <br /> ' incorporates the parent rock material plus jointing and other characteristics <br /> which influence behavior of the mass. This classification is based primarily <br /> on the low strength of the parent rock material, but also on the three joint sets <br /> ' and the low shear strength of some of the joints due to the smooth surfaces <br /> and weathering. This classification may change as additional rock is exposed <br /> in this area. <br /> In general, the joint orientations are neither advantageous nor detrimental to <br /> slope stability. Although the primary jointing is often advantageous (i.e. <br /> dipping into the slope), significant variations exist and secondary jointing is <br /> often disadvantageous. Localized areas of instability were observed in <br /> 15 G:\PROJEC7S\20200\002\96ANNRPT.WPD <br /> `® w <br />