PERMFILE129277

• Permit No: M2005065
• IBM Index Class Name: Permit File
• Doc Date: 3/3/2006
• Doc Name: Adequacy Issues
• From: Charles R. Ponchak
• To: DMG
• Media Type: D
• Archive: No

WestWater Associates, Inc.
Mr. Charles Ponchak
Geological Consultant
15292 6950 Road
Montrose, CO 81401
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Re: Upper Animas Sand & Gravel Complex 110c Application, File #M-2005-065
Sir:
TIM L. DECKER, C.P.G.
306 WEST MAIN
MONTROSE, CO 07407
(870) 2405803
FAX [phone]
Job #106-P
Ponohak
January 25, 2006
As per our verbal discussion and agreement, you requested the assistance of WestWater Associates, Inc. in
evaluating adequacy of the above referenced application to the Colorado Division of Minerals and Geology for
a new gravel pit operation. You have prepared the baseline work and made submittals to DMG fora 5.9-acre
excavation on the property of Jack and Barbara Clark. Preliminary review by DMG had raised questions (Letter
of December 22, 2005, Mr. Wallace Erickson, EnJrronnrental Protection Specialist, Durango Office), as to
erosion potential of a side channel which presently exists and transects the site.
You requested that W WA investigate the hydrology mrd stability of the site, and conduct the following:
1) Evaluate flows of the Aromas River adjacent to the site and the potential for over bank flooding in to the
proposed pit area
2) Potential for headword and down gradi~t erosion at the terminal ends of the pit due to high flows;
3) Potential for river recapture by the pit, should high flow evems occur (all questions raised in DMG
correspondence).
In order to provide a preliminary opinion regarding the above questions, W WA conducted the following:
1) Reviewed applicatiott in its present form, as prepared by Fonchak; reviewed additional correspondence from
DMG; including maps, drawings, exhibits, Reclamation Plan, etc.
2) Accessed USGS historic flows, as measured at gauges at Howardsville (one mile south), Sdverton (above
Cement and Mineral Creek), as well as looked at the Cement Creek, and Silverton below Mineral Creek gauges.
3) Accessed FEMA Records and Floodplain Mapping.
4) Reviewed aerial photographs of the area for re-familiarization with location; revisited the site (has been
observed on numerous occasions over several years) for site inspection (at this time approximately five feet of
snow on the ground; therefore no actual river hydrology or surveying have been conducted to date).
5) Compilation of available flow data for Howardsville and Anhnas at Silverton Gauges; includes analysis of
peak flows and probability of excedence.
6) Prepare this preliminary memo of opinion and recommendations for your use with Permit Application.
Location and Setting: The Clark Property and proposed pit is located in NWll4, SWl/4 and SWl/4, NWl/4,
Section 31, T42N, R6W, NMPM, approximately five miles up the Animas .River from the Town of Silverton. ]t
is also approximately one mile upstream ofthe now abandoned Howardsville Mill. (Reference Ponchak Exhibit
A-2 Location Map). The entire site between the abandoned railroad tracks on the east side of the valley and
main charurel (s) of Animas River to the west. The proposed pit will excavate gravel beginning at the south end,