GENERAL33622

• Permit No: C1984065
• IBM Index Class Name: General Documents
• Doc Date: 10/3/1984
• Doc Name: Letter & Draft Findings
• From: MLRD
• To: Storm King Mines, Inc
• Permit Index Doc Type: Findings
• Media Type: D
• Archive: No

21
XVII.
05.3(8
The Division cannot presently write findings for this section. The following
are the Division's comments:
The applicant has responded to our comments contained within our earlier
adequacy review, which dealt with deficiencies contained in Appendix 3.3-3a.
The amendments are made in the form of amended pages to the original
consultant's report, prepared by Chen and Associates, Inc. However, nothing
was submitted in the supplemental submittals to attest that the report, as
amended, is still certified by Chen and Associates, Inc. The applicant should
submit a certification statement prepared by Chen and Associates which
certifies the consultant's authorship of the amendments. The following
comments assume receipt of that certification statement.
(1) The applicant has performed a pseudo-static seismic stability analysis
of the proposed life-of-mine configuration for the 300' high coal
processing waste slurry embankment. The applicant has applied a
horizontal acceleration factor of 0.1, as recommended by Mr. Rohe Junge
of the Colorado Geological Survey. Unfortunately, the analysis
performed determined the pseudo-static slope stability safety factor of
the life-of-mine structure to be l.l. Rule 4.11.5(3)(a)(ii)
specifically requires that the seismic safety factor for such
structures "be at least 1.2". The applicant will have to amend the
engineered design, in order to achieve the required seismic safety
factor.
(2) In response to our earlier comments regarding verification of the
durability of the coarse refuse fraction, proposed to be utilized to
construct the upper and outer portions of the zoned embankment, the
applicant has provided a response on page 16a of amended
Appendix 3.3-3a. This response theorizes that the hydraulic mining
process would result in segregation of the more durable coarse refuse
fragments.
Unless the applicant amends the permit application to commit to the
following, our eventual findings document will include a stipulation
which imposes the consultant's recommendations, presented on page 16a,
upon the approved plan. This stipulation will impose the conducting of
"visual inspection of the coarse refuse material" as well as the
performance of "point load tests" to verify the results of the visual
inspection. Further, that stipulation should impose requirements to
develop specific point load testing criteria for use in performing the
tests and require the periodic submittal of certified reports
presenting the test results to the Division.
(3) In response to our earlier comments requiring the elaboration of the
application's discussion regarding detection and treatment techniques
to be used to preclude development of hydrocompactible soil problems in
the foundational soils beneath the proposed pile, the consultant has
amended page 22 of Appendix 3.3-3a. The amended text commits the
applicant to the testing of in-place dry density and liquid limits of
the foundational soils, which the USGS has allegedly correlated to the
collapsible nature of soils. Our eventual findings will reiterate the
commitment made on page 22 of amended Appendix 3.3-3a, verbatim.