PERMFILE134266

• Permit No: C1980007
• IBM Index Class Name: Permit File
• Doc Date: 12/11/2001
• Section_Exhibit Name: EXHIBIT 70 REFUSE PILE EXPANSION
• Media Type: D
• Archive: No

REFUSE PILE EXPANSION

~~

to obtain suitable samples for direct shear and
triaxial testing.
Two permanent 2-inch diameter slotted Schedule 40
PVC piezometers were installed in borings LRP-1
and LRP-4 during the October, 1995, drilling
program. The other borings were sealed and
abandoned in accordance with exploration Notice of
Intent to Explore (NOi) No. X-95-212-04. The
piezometer borings were placed on the approximate
border of the proposed RPE foundation footprint.
The piezometers were installed in order to obtain
groundwater elevations and water quality
information prior to and during construction of the
proposed RPE. Both piezometers were installed as
per the requirements of the NOI X-95-212-04. The
slotted screen section of each piezometer was
established as close to the bedrock surface as
possible. The piezometer borings were backfilled
with Ottawa course grained sand to within ten feet
of the natural surface. A seven foot concrete plug
(to stop surface water infiltration into the boring)
was placed from three feet to ten feet below surface.
The remaining portion of the piezometer borings
were filled with auger cuttings and soil. The logs of
the piezometer installations can be found in
Appendix F of this report.
5.2 Laboratory Testing
The laboratory testing program conducted on the
soil samples retrieved from the drilling investigation
included gradation tests, moisture content
determination, Atterberg limits, and triaxial shear
testing. The laboratory testing was conducted by
Garco Testing Laboratories of Salt Lake City, Utah,
and Colorado State University's soil laboratory. All
testing utilized the appropriate ASTM procedures.
The Shelby tube soil samples tested for triaxial
shear strengths values consisted of predominantly
gravely-sandy soils. Due to the very granular nature
of [he gravely soils in the proposed RPE area, only
two Shelbv tubes could be obtained. The results of
the triaxial shear testing are found in Appendix G.
The gradations, moisture contents and Atterberg
limits of [he soils can be found in Appendix G.
5.3 Geology
5.3.1 Introduction
This section presents the results of the geologic
engineering mapping of the proposed RPE site. The
purpose of the geologic engineering mapping was to
evaluate the presence of geologic and hydrologic
features that may impact the development of the
proposed RPE. The proposed RPE will be used by
MCC for consvucting a fill of coal refuse generated
by future coal mining operations. As part of this
geologic engineering mapping, HLA:
• conducted a field evaluation of landslide and
landslide prone areas within the proposed
limits of the RPE; and
• examined and evaluated all hydrologic
features and associated Flows within and
outside the proposed limits of the RPE.
5.3.2 Background
The following section is a brief discussion of site
location and previous site investigations.
5.3.2.1 Location/Site Description
The West Elk Mine (WEM) site is located two miles
east of the town of Somerset, Colorado, to the south
of the North Fork of the Gunnison River, and
approximately six miles west of Paonia Reservoir.
The WEM is an active underground coal mining
operation.
The proposed site for the development of the RPE is
currently an undeveloped section of land owned by
MCC. The site is located on the lower portion of an
area referred to as the West Flatiron and is bordered
by Highway 133 on the north, Sylvester Gulch on the
west, and an unnamed gulch between Sylvester Gulch
and Box Canyon on the east. The site is generally
vegetated with Gambel oak, spruce, and aspen trees.
Historical development of this area is limited to an
old jeep trail through [he central portion of the site,
and an abandoned cistern and stock watering tank
on the east Flank of Sylvester Gulch.
5.3.2.2 Site Investigation
Harding Lawson Associates
4