HYDRO24727

• Permit No: M1999002
• IBM Index Class Name: Hydrology
• Doc Date: 12/8/2006
• Doc Name: Cavity Characterization Study for Well 28-21
• From: DRMS
• To: American Soda, L.L.P.
• Media Type: D
• Archive: No

E'SC'I~C~jI ~,~~~tll Ccs ~~~
STATE OF COLORADO
DIVISION OF RECLAMATION, MINING AND SAFETY
Department of Natural Resources
7373 Sherman St., Room 215
Denver, Colorado 60203
Phone: [phone]
FAX: [phone]
/December 8, 2006
Mr. Ed Cooley
American Soda, LLP
2717 County Road 215
Pazachute, CO 81635
r/
RE: American Soda, LLP, Yankee Gulch Minerals Project, Permit No. M-1999-002
~ity Characterization Study for Well 28-21
Dear Mr. Cooley,
COLORADO
DIVISION OF
RECLAMATION
MINING
-&-
SAFETY
Bill ovens
Governor
Russell George
Executive DIreCIOr
Ronald W. Canany
Division Director
Natural Resource Trustee
Thank you for resubmitting two copies of the 2004 Cavity Chazacterization Study for American
Soda we1128-21. The study was submitted within months of American Soda's decision to cease
production at the site, and mothball the current operations. Since the notice of temporary
closure of the site, American Soda actively engaged in reclamation of the site, In particular
American Soda has either permanently or temporarily sealed and abandoned all of the
production wells within the original s year mine panel, removed the piping and structures from
the wells, re-contoured the well pads, replaced topsoil and revegetated the reclaimed areas.
American Soda is in the process of reclaiming the facilities in the Pilot Plant area including
removal of piping, fencing, netting removal of the pump house and reclamation of the pond and
pond area. Please be reminded that when most of the reclamation of the site is complete,
American Soda will need to change the status of the operation from "active" to "temporary
cessation". This can be facilitated as a Temporary Cessation application revision to the permit.
Although mining has ceased and the site is being reclaimed, the Division feels that it is
necessary to comment on the 2004 Cavity Characterization Study and any future mining
proposed by American Soda under the Yankee Gulch Minerals Project.
The study was pre~azed by NSA Geotechnical Services, lnc. using NSA's Seismic Reflection
Technology (TRT ). The survey uses a fixed array of about 10 sensors and seismic sources
initiated at different locations within We1128-21 to obtain a velocity model from the reflected
seismic waves. Based on the velocity model, the test survey provided images of the
underground features within the solution mining zones. Fluid displacement in the top 10 to 20
feet within the cavity was displaced with nitrogen gas to develop a cavity volume relationship
used to cross check the seismic representation of the cavity shape and size. The model was
compazed to the historical production data for We1128-21, whereas the model was 6% greater
than the historical production. Based on the report, it appears that the TRTTM model provides
an adequate representation ofthe underground features within the solution mining zone.
American Soda projected the TRTm" model to each ofthe production veils to determine the
extent of the wells within the dissolution zone. The diameter of each of the wells was pornayed

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