|
<br />69. Rule 6.1 states that reclamation grading shall be carried on so as to
<br />create a final topography appropriate to the final land use selected in
<br />the reclamation plan. The proposed final configuration of the east pit
<br />(75 ft. benches with highwalls 50 ft. in height and 90 ft. slope lengths,
<br />approaching 1.SH:lY,) does not appear to be appropriate to the final land
<br />use designated as rangeland and wildlife habitat. It should he noted
<br />that this configuration does not appear to be consistent with the
<br />contours shown on Figure F-1. Slopes steeper than approximately 4H:lY
<br />become exceedingly difficult to establish vegetation, inhibit livestock
<br />utilization (Stoddard, Smith, and Box, 1975), and are more susceptible to
<br />erosion and resulting sedimentation of drainages. Reclamation of the
<br />proposed final configurations of the east pit is further hampered by the
<br />south facing slope-aspect and coarse textured, erodible sub- and topsoils
<br />available for replacement, both conditions known for moisture
<br />deficiencies and adverse impacts upon vegetation establishment: and
<br />maintained growth. Cook, Hyde, and Sims, 1974, specify that ~n Sagebrush
<br />Foothill Vegetation Types, "all south and west-facing slopes <_.hould not
<br />be steeper than four to one, and five to one, where possible.
<br />North-facing slopes should not be steeper than three to one." Cook,
<br />et.al., further specified that in Foothill Juniper Vegetation Types, "If
<br />possible all south and west-facing slopes should not be more than four to
<br />one and north and east-facing slopes not more than three to one."
<br />Approval of the Earth Resources, Inc. 1983 amendment was recommended by
<br />the staff following agreement with the operator that the final pit slope
<br />configurations would range from 1.25 to 4 horizontal to 1 vertical, and
<br />that any slopes greater than 30 degrees, or 1.75H:1V would be broken with
<br />a series of terraces.
<br />It is recommended that the east pit be filled to capacity witfr the waste
<br />rock generated from the west pit, and the final topographic
<br />configurations approach that of the pre-mining contours. Ple~rse discuss.
<br />Section E.3.2 Waste Rock Disposal Areas
<br />70. Rule 6.1, states that reclamation grading shall be carried on so as to
<br />create a final topography appropriate to the final land use selected in
<br />the reclamation plan. The proposed final configuration of wa~:te rock
<br />piles A, B, C, and the south disposal area (75 ft. benches with 50 ft.
<br />slopes and 90 ft. slope lengths, approaching 1.5H:1V), does not appear to
<br />be appropriate to the final land use designated as rangeland e.nd wildlife
<br />habitat. Slopes steeper than approximately 4H:1V become exceedingly
<br />difficult to establish vegetation, inhibit livestock utilization
<br />(Stoddard, Smith, and Box, 1975), and are more susceptible to erosion and
<br />resulting sedimentation of drainages. Reclamation of the proposed final
<br />configurations of the waste rock piles is further hampered by the south
<br />facing slope-aspect (areas A, B, and C) and coarse textured, erodible,
<br />sub- and topsoils available for replacement, both conditions 4:nown for
<br />moisture deficiencies and adverse impacts upon vegetation establishment
<br />and maintained growth. Cook, Hyde, and Sims, 1974, specify that in
<br />Sagebrush Foothill Vegetation Types, "all south and west-facing slopes
<br />should not be steeper than four to one, and five to one, where possible.
<br />North-facing slopes should not be steeper than three to one." Cook,
<br />et.al., further specified that in Foothill Juniper Vegetation Types, "If
<br />possible all south and west-facing slopes should not be more than four to
<br />one and north and east-facing slopes not more than three to one."
<br />-12-
<br />
|