2017-05-26_REVISION - M1996060

• Permit No: M1996060
• IBM Index Class Name: Revision
• Doc Date: 5/26/2017
• Doc Name: Adequacy Review Response
• From: Hall-Irwin Aggregates, LLC
• To: DRMS
• Email Name: ECS
• Email Name: BJC
• Media Type: D
• Archive: No

ROCKY MOUNTAIN CONSULTANTS, INC. RMIC
Premiere Building
825 Delaware Ave., Suite 500
Longmont,CO 80501
[phone]
Metro [phone]
FAX [phone]
June 20, 2000 (first initial,last name)@long.rmcco.com
Mr. Jeff Gregg
Hall-Irwin Corporation
P.O. Box 519
Greeley, Colorado 80632
Re: Hall-Irwin Corporation, Tigges and Roberts Properties, Firestein Site, MLRB 112,
M-1996-060; RMC Job No. 80-0636.055.00
Dear Mr. Gregg:
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 part of the Firestein
Mine.
The proposed gravel mine area subject to this letter will be located on the Tigges and Roberts properties
in part of the south half of Section 30, Township 6 North, Range 66 West, and in part of the northeast
quarter of the northwest quarter of Section 31, Township 6 North, Range 66 West in Weld County,
Colorado. Land use in the area is predominantly irrigated agricultural farm land, sand and gravel
mining, and oil extraction from area wells. Plans are to mine parts of the Tigges property in six mine
cells ranging in size from approximately 7.2 to 22.6 acres, and to mine part of the Roberts property in
one mine cell of approximately 48.6 acres. The proposed mine cells are south of Weld County Road
64'/z, west of Weld County Road 27 (aka, 83rd Avenue), and north of the Cache la Poudre River. The
mine cells will be dewatered with perimeter drainage ditches.
GEOLOGIC STRATA
The south part of the Tigges property is located on a low river terrace deposit near the Cache la Poudre
River. The north part of the Tigges property, as well as the entire Roberts property, are located on a
higher (older) terrace deposit further away from the river.
Logs of borings completed in the Tigges property indicate the Tigges site soils consist of approximately
five to 13 feet of sandy clay and clayey sand overburden soil, on top of approximately four to 29 feet of I
sand and gravel, overlying sandstone and claystone bedrock. The boring data indicate the sand and
gravel deposit is thicker on the terrace on the north part of the Tigges property than on the lower terrace
near the river. Logs of borings completed on the Roberts property indicate the soils on the Roberts site
consist of approximately nine to 12 feet of sandy clay and clayey sand overburden soils overlying
approximately 19 to 28 feet of sand and gravel on top of sandstone and claystone bedrock.
From a geotechnical standpoint, the sand and gravel will form most of the mine slopes. These soils are
generally strong and stable, particularly when dewatered.
CIVIL AND ENVIRONMENTAL ENGINEERING - PLANNING