REV09300

• Permit No: C1981019
• IBM Index Class Name: Revision
• Doc Date: 1/2/1990
• From: OSM
• To: DNR
• Type & Sequence: PR1
• Media Type: D
• Archive: No

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manner. Placeaeat of material in naifon horizontal lifts is
• required to prevent pockets ar leases of material dif#ering in
moisture content, texture, and gradation from alreaay-placed
material. eorizontal lifts alloy sufficient blending and proper
bonding of aggregate material to secure the best practicable degree
of compaction. Rorizoatal lifts also avoid development of lateral
slip surfaces that occur during end-dumping which can not be
accounted for during an analytical analysis. Finally, the use of
horizontal lifts will alloy repreaeatative field-testing to occur;
thus, verlfyinq the assumptions used in the design.
Approval of the proposed revisions could potentially result in the
folloving scenario. Implementation of Rule 4.09.I(3) rauld not
specifically regaire a static safety factor of 1.5 for a compaction
performance standard (as regaired by 30 CFR 816.71(b)(2)%Si7.71(b)(2)).
Zt would also alloy Colorado to remove the following: the
requirement of keyway cuts when the elope is the disposal area
exceeds 2.Sh:ly (36 percent) (as required by
30 CFR 616.71 (d)(2)/817.71(d)(2)), the requirements of fill
inspections by a qualified registered professional engineer or
other qualified professional specialist at least quarterly during
construction sad during the critical phases of construction (as
required by 30 CFR 816.71(h)/SI7.71(h)), the requirement of
uaderdrains with filters, and the requirement of a drainage control
system capable of safely passing the runoff from a 100-year,
24-hoar precipitation event las required by
• 30 CFR 816.71(f)(1),(2),(3)/BI7.71(f)(1),(2),(3)).
It is necessary in western States that construction of stable fills
must not only use acceptable construe=ion techniques, but must also
ccasider the region's climatic situation. In other words,
construction during the winter is ceased to protect the integrity
of the construction and restarted when the weather permits. In
other semiarid areas in the Hest, realizing that is situ materials
do not contain enough moisture to alloy sufficient comaaction,
cater is imported. OSHRE, however, is not familiar with any coal
mines where fills exist in Colorado where eater is a scarce
commodity. Construction of valley fills and head-of-hollow fills
must not only use acceptable construction techniques not use a
common-sense approach to ciimatac conditions.
To be no less effective than the Federal regnlatioas, Colorado must
not apply the general fill variance found at Rule 4.04.1(3) to the
valley fill and head-of-hollow fill provisions at Rules 4.09.2 and
4.09.3.
&-B Ruie 4.09.3; 30 CFR 816.72/817.72 (Bead-of-Hollow FiI'_s)
Colorado submitted a formal revision, to Rule 4.09,3 in
C~-384. See the OSHRE issue letter dated February 7, '_989 for
disposition of Item 6-B.

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