2008-12-10_REVISION - M1999120

• Permit No: M1999120
• IBM Index Class Name: REVISION
• Doc Date: 12/10/2008
• Doc Name: Additional Information
• From: L.G. Everist, Inc.
• To: DRMS
• Type & Sequence: TR3
• Email Name: ECS
• Media Type: D
• Archive: No

L.G. EVERIST, INC.
December 10, 2008
Mr. Eric Scott
Environmental Protection Specialist
Division of Reclamation, Mining and Safety
1313 Sherman St., Room 215
Denver, Colorado 80203
CORPORATE OFFICE
300 S. PHILLIPS AVE. • SUITE 200
P.O. BOX 5829
SIOUX FALLS, SD 57117-5829
PHONE [phone]
FAX [phone]
MOUNTAIN DIVISION
7321 E. 88TH AVENUE • SUITE 200
HENDERSON, COLORADO 80640
303-287-9606
FAX [phone]
RE: M-1999-120, Fort Lupton Sand and Gravel Mine, TR-03, Additional Information
Dear Eric,
We are respectfully submitting additional information for the revisions in the backfill amounts I
discussed with you in November for the Technical Revision JR) listed above. My apologies for
the delay in this response. At the same time, I want to clarify a few other items we discussed.
To refresh both our memories - L. G. Everist, Inc. (LGE) sent information in to the Division of
Reclamation, Mining, and Safety (DRMS) for a Technical Revision to increase the bond to cover
the remaining unbonded phases of the Fort Lupton Sand and Gravel mine, M-1999-120. The
bond was calculated at a total of around $2.5 million due in large part to the huge amount of
backfilling required. With such a substantial increase, we decided we needed to get more
accurate backfill numbers than the backfill estimates that had been done in conjunction with our
permitting applications that I gave you in our TR-03 Adequacy Review Response from October.
The information on the new backfilling amounts listed below will allow you to re-calculate the
whole bond for the Fort Lupton site.
As mentioned above, and as we discussed, we would like for the Division to use the more
accurate backfill numbers listed in the table below rather than the backfill estimates that had
been done in conjunction with our permitting applications and which I submitted previously.
Because the difference in backfill amounts is substantial, following is an explanation as to how
the revised backfill numbers were derived. The more accurate backfill numbers were calculated
by Matt Noteboom, an L. G. Everist, Project Engineer. He explained to me that he performed a
topographic survey of the original grade using a survey-grade GPS unit. He collected all past
exploration data we had for the site and created a 3D digital terrain map (DTM) of the bedrock
surface. He then used the in-place slurry wall alignment (for slurry walls already constructed)
and the pre-design slurry wall alignments (for the remaining phases) to calculate the final
alignments of each phase's highwall and toe of its 3:1 slopes. Using the 3D elevation difference
in the original grade survey, the final slurry wall top elevations, and the bedrock contours, he
modeled the amount of backfill required for the slope reclamation using a survey program called
Foresight. To finally calculate the backfill volumes required for reclamation, he assumed an
average pit depth multiplied by the slope lineal footage. He also explained that the 3D model
gives a much more accurate estimate than the pre-mining estimates that I had submitted earlier.
F L-DRMS-TR03-Rev is i o n s-to E S-121008. d o c