2009-11-13_PERMIT FILE - C1982056 ‎(3)‎

• Permit No: C1982056
• IBM Index Class Name: Permit File
• Doc Date: 11/13/2009
• Section_Exhibit Name: Exhibit 26C Coal Refuse Disposal Area Expansion
• Media Type: D
• Archive: No

• 4) Initial placement of the coal refuse should be observed and tested to evaluate the material
properties and compaction procedures established in the existing CRDA are adequate.
5) Compaction testing and observation of the fill materials and placement methods must be
performed on a regular basis as the CRDA construction proceeds. The frequency will depend on
the rate of pile construction. As a minimum, the fill materials should be tested at least every 4 feet
vertically.
6) We recommend the construction of three wells to monitor water conditions within the pile. The
monitor wells should be constructed when the fill materials have been placed to a height of at least
50 feet. The wells will consist of slotted 2 -inch Schedule 40 PVC pipe with a sand pack. The
wells will extend at least 5 feet into the foundation materials and be constructed with a protective
steel casing and lockable cap.
Limitations
The recommendations given in this report are based on the subsurface conditions encountered in the test
holes and pits, and those encountered in the construction of the current CRDA. The test holes and pits
were widely spaced to determine the general subsurface profile in the CRDA. We believe that this
information gives a high degree of reliability for anticipating the performance of the constructed slopes;
however, our recommendations are professional opinions and cannot control nature, nor can they assume
• the soils and groundwater conditions beneath or adjacent to those observed. We do not guarantee the
performance of the constructed slopes in any respect, only that our engineering work and judgments
rendered meet the standard of care of our profession. The CRDA construction must be inspected, as
required by the Regulations of the Colorado Mined Land Reclamation Board for Coal Mining, to confirm
the conditions exposed during excavation and construction of the slopes and drainage are as anticipated in
this design. The field monitoring will identify unanticipated conditions and allow adjustments to the
design and construction methods. Uncontrolled modifications could adversely affect the stability of the
constructed slopes.
If you have any questions regarding this report or if we may be of further service, please do not hesitate to
contact us.
Sincerely,
NWCC, INC.
Tim k‘ ''as• - •;
Reviewed by Brian ° `
;' 1 1
•
Job Number: 08 -7915 NWCC, Inc. Page 12
Revised 10/12/09