GENERAL56446

• Permit No: C1981019
• IBM Index Class Name: General Documents
• Doc Date: 8/22/2005
• Doc Name: Lower Wilson Alluvial Valley Floor Determination
• From: Walsh Environmental Scientists and Engineers, LLC
• To: DMG
• Permit Index Doc Type: General Correspondence
• Media Type: D
• Archive: No

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Environmental Scientists and Engineers, LLC o::._
August 16, 2005
Mr. James R. Stark
Environmental Protection Specialist
Colorado Division of Minerals and Geology
Department of Natural Resources
1313 Sherman Street, Room 215
Denver, CO 80203
Subject: Alluvial Valley Floor Determination
Lower Wilson Mining Area Expansion Project RECEIVED
Colowyo Coal Company
Meeker, Cotorado AUG 2 2 2005
WALSH Project /1 6025-010
Uivisian ~f Minerals and Geology
Dear Mr. Stark:
Walsh Environmental Scientists and Engineers, LLC (Walsh) was contracted by Kennecott
Energy on behalf of Colowyo Coal Company (Colowyo) to prepare permit revision documents
for the expansion of the current mining operation to include the Lower Wilson Mining Area
shown on the attached figure. As discussed during our meeting on August 9, 2005, three areas
along Wilson Creek have been identified or assumed to be alluvial-valley floors. These areas
are shown on the attached figure and include the currently existing agricultural area located
south of the Lower Wilson Mining Area access road (Area 1), portions of the area located
along Wilson Creek extending from the north side of the Lower Wilson Mining Area access
road through Section 5 of Township 3 North, Range 93 West and Sections 32, 33, and 28 of
Township 4 North, Range 93 West (Area 2), and the area included in Sections 21 and 22 of
Township 4 North, Range 93 West (Area 3).
Area 1 will not be impacted by mining operations due to the location of the area relative to the
mining area. The area is located hydrologically up-gradient of the mining operations.
Much of Area 2 along Meeker County Road 51 (Wilson Creek Road) was deeply entrenched
by ahighly-erosive mass wasting event in 1985. Incision of the creek bed effectively drained
the sub-irrigation aquifer from Area 2 to a depth of generally 50 feet. This was confirmed by
two alluvial monitoring wells installed at the confluence of the unnamed drainage extending up
valley into the mining area and Wilson Creek (wells MW-95-03A and MW-95-O3B). Both
wells were installed to bedrock and completed with slotted-well casing. The location of the
wells is shown on the attached figure.
The impacts to Area 3 will be minimal and will be limited to construction of a gravel haul road
to provide access to the Gossard Loadout. The haul road will have stormwater impoundments
to collect surface water runoff. At the completion of mining activities, the haul road will be
removed and the area will be reclaimed. The haul road disturbance area will be included in
the mine reclamation bond. In order to monitor the quality and quantity of water in surface or
underground water systems that supply the AVF, Colowyo installed alluvial groundwater
monitoring well MW-95-02 in Area 3 as shown on the attached Figure. Colowyo collected
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