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ROCKY MOUNTAIN CONSULTANTS, INC. <br />Inc <br />A TETRA TECH COMPANY <br />1900 S. Sunset Street, Suite 1-F <br />Longmont, CO 80501 <br />(303) 772-5282 <br />FAX (303) 665-6959 <br />November 19, 2002 <br />Mr. Jim McFarland <br />Hall-Irwin Corporation <br />P.O. Box 519 <br />Greeley, Colorado 80632 <br />F~EGE9~ss^!~ <br />MAY 12 2004 <br />Ilivisian of Minerals & GeoloBY <br />Re: Hall-Irwin Corporation, Bernhardt Property; RMC Job No. 80-0636.137.00 <br />Dear Mr. McFarland: <br />This letter has been prepared to address Construction Materials Rule 6, Section 4, Subsection 19, <br />Exhibit S -Permanent Man-Made Structures (6.4.19, Exhibit S) for the above-referenced proposed <br />aggregate mme. <br />The proposed mine will occupy the Berthardt property located in part of the south half of Section 1, <br />Township 4 North, Range 67 West of the 6th Principal Meridian in Weld County, Colorado. The site is <br />immediately north of Weld County Road 48, west of Weld County Road 25, and east of Weld County <br />Road 23. The Big Thompson River bisects the site. Land use in the area is mostly agricultural and rural <br />residential with newer encroaching residential and commercial developments. Numerous gas wells are <br />present in the area. The City of Milliken wastewater treatment plant is adjacent to the south part of the <br />site. <br />Plans are to mine the site in five pods ranging from approximately 17 to 61 acres in area. Pods 1 <br />through 4 will be south of the Big Thompson River. Pod 5 will be on the north side of the river. Slurry <br />walls will be constructed around Pods 2, 4, and 5 prior to mining. For our analyses, we have assumed <br />that the mine highwalls on the perimeter of each pod will be no steeper than 0.5:1 (horizontal to <br />vertical). Overburden stockpiles will be placed on the perimeter of Pod 1. No such stockpiles will be <br />placed near the other pods. Pods 2, 4, and 5 will be reclaimed as lined ponds. Pods 1 and 3 will be <br />reclaimed as unlined ponds. <br />GEOLOGIC STRATA <br />The mine site is located in the alluvial valley of the Big Thompson River approximately four miles <br />upstream of its confluence with the South Platte River. Geologic mapping by Colton (1978)1 indicates <br />most of the mine will be in the Post Piney Creek and Piney Creek Alluviums. A small part of Pod 4 <br />maybe in the Broadway Alluvium. The mapping indicates the bedrock underlying the alluvium is <br />either the Fox Hills Sandstone or claystones and sandstones of the Upper Transition Member <br />of the Pierre Shale. Outcrops of Fox Hills Sandstone form bluffs on the north side of the alluvial valley. <br />Colton, R.B., 1978, "Geologic Map oj~he Boulder-FC Collins-Greeley Area, Colorado," USGS Map I-855G. <br />CIVIL AND ENVIRONMENTAL ENGINEERING PLANNING <br />www.rmcco.com <br />