PERMFILE43696

• Permit No: M2000087
• IBM Index Class Name: Permit File
• Section_Exhibit Name: EXHIBIT J VEGETATIVE INFORMATION
• Media Type: D
• Archive: No

ROCKY MOUNTAIN CONSULTANTS, INC.
Inc
June 30, 2000
Mr. Norm Roche
Aggregate Industries
3605 South Teller Street
Lakewood, Colorado 80235
~~
Premiere Building
825 Delaware Ave.. Suite 500
Longmont. CO 80507
[phone]
Metro [phone]
FAX [phone]
(first Initial, last name)@long.rmcco.com
Re: Aggregate Industries, Proposed Gravel Mine, Milliken Site; RMC lob No. 80-0137.086.00
Dear Mr. Roche:
This letter has been prepared to address Construction Materials Rule 6, Section 4, Subsection 19,
Exhibit S -Permanent Man-Made Structures (6.4.19 Exhibit S) for the above-referenced proposed
gravel mine.
The proposed gravel mine will be located on approximately 205 acres of land located in part of the
West Half of Section 8 and part of the Northwest Quarter of the Northeast Quarter of Section 8,
Township 4 North, Range 66 West in Weld County, Colorado. The site and surrounding area are
predominantly irrigated agricultural land. Gas wells and their associated separators and tank
batteries are also present at the site and in the surrounding area. Plans are to mine parts of the site
in five cells ranging in size from 6.1 to 40 acres. Mine slopes will be 2:1 (horizontal to verticaq.
The cells will be encircled by low permeability slurry walls. The proposed mine site is located in
the South Platte River valley on the northwest side of the river.
SITE GEOLOGY
We performed an engineering geologic reconnaissance of the site on April 25, 2000. The areas to
be mined are located on two fluvial terraces located above the South Platte River. Review of
regional geologic mapping (Colton, 1978) indicates these two terraces consist of deposits of the
Piney Creek and Broadway Alluviums. Bedrock underlying the alluvium is most likely the Laramie
Formation though mapping indicates the contact with the Fox Hills Sandstone is nearby and could
be under the site (Colton, 1978).
Logs of four exploratory borings drilled at the site indicate the site stratigraphy consists of
approximately four to six feet of fine-grained overburden soils overlying the sand and gravel
aggregate deposit. The sand and gravel contains local clay lenses ("mud lenses") and extends to
depths of at least 39 to 58 feet (the drilled depth of the borings).
From a geotechnical standpoint, the sand and gravel will form most of the mine slopes. These soils
are generally strong.
CIVIL AND ENVIRONMENTAL ENGINEERING PLANNING