APPCOR12350

• Permit No: C1982056
• IBM Index Class Name: Application Correspondence
• Doc Date: 11/19/1982
• Doc Name: ADEQUACY OF GEOTECHNICAL ASPECTS OF THE FOIDEL CREEK APPLICATION
• From: MLR
• To: SANDY EMRICH
• Media Type: D
• Archive: No

• _q_ •
modification from the alternatives analyzed and recommended within
the consultants report, Exhibit 8. The spoil slope maximum grades
are depicted as 1.5:1 (horizontal to vertical slope), which the
consultant recommended only for the short term plan. If the applicant
reapplies for a long term approval in the future, this slope would
require modification to conform with the recommended slope gradient
of 2:1 (horizontal to vertical slope). This should be clearly
understood by the applicant and will be clearly stated within oUr
findings document.
(2) The applicant's consult, CTL/Thompson, Inc., performed a stability
analysis, presented in Exhibit H, which is in keeping with the
prudent state-of-the-art of slope stability analysis. In completing
this analysis, the consultant made several material strength assumptions
regarding the existing spo~i'ls and an underlying fireclay. These
assumptions appear warranted, if the amended properties are verified
through appropriate monitoring of the modified spoil .and highwall j
slopes. In fact, CTL/Thompson, Inc., recommends periodic inspection
and monitoring of these slopes to a"ssure proper performance (see page
26 of Exhibit 8). The applicant should prepare a monitoring program
for the modified spoil and highwall slopes. Appropriate survey
monumen~tation should be installed following construction, and
monitored in conjunction with periodic inspections performed on a
mutually acceptable frequency. This is particularly important in
light of the short term slope configurations being proposed within the
permit application for the current permit period and mine plan.
(3) The applicant's consultant states, within Exhibit 8, that it is
important to carefully control surface drainage within the vicinity
of the modified highway and spoils slopes. The applicant has not
provided sufficient detailed information regarding the surface
drainage above the modified highway. The applicant should provide
additional detail to assure that the highwall area will be properly
drained in order to avoid infiltration of surface water which could
affect the stability of the filial highwall.
(4) Since the applicant's consultant projects the occurrence of shallow
slope failures on the modified spoil slope at the steeper configurations
proposed for the temporary project, the applicant should provide
deflector structures to protect the portals from damage in the event
a failure occurs (see page 26 of Exhibit 8).
/ep