HYDRO31667

• Permit No: C1981018
• IBM Index Class Name: Hydrology
• Doc Date: 10/28/1996
• Doc Name: Pond RP-4 EMBANKMENT INVESTIGATION
• From: DMG
• To: WESTERN FUELS-UTAH
• Permit Index Doc Type: SEDIMENT POND INSPECTIONS
• Media Type: D
• Archive: No

STATE OF COLORADO
DIVISION OF MINERALS AND GEOLOGY
Department o(Naiural Resources
1313 Sherman St., Room 215
Denver, Culorado 80203
Phone: [phone]
FAX. (303) B32-8106
DATE: October 28, 1996
T0: Dan Mathews
FROM: Jim Pendleton~!~
RE: Geotechnical (Invest
Embankment Cracking
II~~~
DEPARTMENT OF
NATURAL
RESOURCES
Roy Romer
Governor
lames 5. Lochhead
Execwive Direcor
Mu: hael B. long
Division Director
ion of Sediment Pond RP-4
- Deserado Mine
I have reviewed the geotechnical investigation report prepared by Lincoln-
DeVore, Inc., geotechnical consultants to Western Fuels-Utah, Inc., owner of the
Deserado Coal Mine. The investigation was performed to determine the cause of
cracking which had been observed on the north embankment of Sediment Pond
R P-4.
In completing their investigation, Lincoln-DeVore, Inc. Completed three auger
borings through the north embankment. These borings penetrated the
embankment and advanced approximately 10 feet into the original subgrade
beneath the embankment. Samples were obtained from the embankment and the
subgrade for laboratory analysis.
Laboratory analysis subsequently determined that al4 the clay soils and
claystone bedrock encountered exhibited varying degrees of expansiove soil
behavior. The subgrade materials were more responsive to saturation and
drying than the embankment soils. The embankment soils exhibited a swell of
0.5%, with pressures of less than 1,000 psf. The native subgrade soils
exhibited swells of etween 1.2% and 1.6%, at pressures ranging from 2,500 psf
to 5,000 psf.
Lincoln-DeVore concludes that the cracking resulted from a general heaving of
the subgrade native soils beneath the embankment. They theorize that water
standing in the pond infiltrated into the embankment and the subsoils. Both