PERMFILE137852

• Permit No: C1981012
• IBM Index Class Name: Permit File
• Doc Date: 12/11/2001
• Section_Exhibit Name: EXHIBIT 30 CTL RDA AND DWP CERTIFICATION PART 2
• Media Type: D
• Archive: No

• October 2, 1997
Lorencito Coal Company, LLC
c/o Greystone
5990 Greenwood Plaza Boulevard, Suite 250
Englewood, Colorado 80111
Attention: Mr. Jerry Koblitz
Subject: New Elk RDA
Lorencito Coal Mine
Las Animas County, Colorado
Job No. 26,600
Gentlemen:
At your request we have reviewed our previous work at the New Elk RDA to
summarize the information available and facilitate mid-term permit review by the
Colorado Division of Minerals and Geology (CDMG). The items reviewed included:
• 1. Supplemental Stability Investigation, Refuse Disposal Area, by
CTL(Thompson, Inc., Weston, Colorado, Job No. 22,478, dated May 10,
1995. This investigation included a review of previous design
documents, and testing performed at the RDA to develop opinions
regarding the stability of the RDA and also to provide recommenda-
tions for RDA configuration and operating procedures. The report
reviewed considerable density testing information performed during
pile construction and also density information based upon borings into
the waste pile. The conclusion was that generally satisfactory
compaction was of the waste material was present. The drilling for this
investigation was performed during November 1994. The elevation of
the borings on the working surface of the RDA at the time of drilling
ranged from 7637 to 7647.
In summary, the investigation indicated the existing RDA configuration
is judged to be stable. A proposed RDA configuration with 2.2:1 (H:V)
slopes between benches, with horizontal benches at 50 foot vertical
intervals was also recommended and considered to be a stable
configuration. We understand this report was intended to be the basis
for a revised operating plan using the new proposed configuration and
construction recommendations.
2. Subsequent to the above investigation, coal waste processing and
• placement on the pile continued until March of 1996. At this time the
CTL/THOMPSON, INC.
CONSULTING ENGINEERS
1971 WEST 12TH AVENUE ~ DENVER, COLORADO 80204 ~ [phone]