GENERAL32098

• Permit No: M1999002
• IBM Index Class Name: General Documents
• Doc Date: 5/14/2004
• Doc Name: Wells 20-19 and 29-20.
• From: American Soda LLP
• To: EPA
• Media Type: D
• Archive: No

AMERICAN ~
SODA, L L P
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Ed Cooley
Environmentol Health and
Safefy Manager
2717 County Road 215
Parachute. CO 81635
Tuesday, May i 1, 2004
Elisabeth Evans
Director Technology Enforcement Prograrp
U.S. Environmental Protection Agency
Region VIII
999 18'h Street, Suite 300
Mail Code 8ENF-T
Denver, Colorado 80202-2466
Direct une [phone]
IntemaTional Telephone +l [phone]
General Facsimile [phone]
ENV. 97.04
RECEE~lED
MAY 14 2004
Olvlelan of Minerals & Geolagv
Re: ~ Its 20-19 (C030858-04556), 29-20(C030858-04569)
Dear Elisabeth:
This letter is a follow up to a telephone conversation I had with Nathan Wiser on Monday, May
3, 2004 in which we discussed operating conditions we will encounter during the phase down
of operations in the well field covered by Area Wide UIC Permit C03858-00000.
As we decrease pressure on the wells to move toward a stabile shut in status there will be a
disproportionate increase in the discharge flow from the well in relationship to the injection
flow into the weft. This will occur because the volume of solution contained within an ASLLP
Piceance solution mining cavity is a function of the production pressure that is maintained on
the cavity. Past operating experience has shown that a reduction in production pressure will
cause the production mass balance to trend positive. (More mass flow being withdrawn from
the cavity than mass flow being injected into the cavity.) This trend will continue until
equilibrium is reached. A higher production pressure causes the effective stress of the outer
wall of the cavity to increase, allowing a larger volume of fluid to be stored within the cavity.
Upon relieving this stress by lowering the production pressure, the outer cavity wall responds
elastically and decreases the volume of fluid that can be stored. This feature is analogous to
specific storage in groundwater aquifer systems.
ASLLP is currently lowering the production pressure on wells 20-19 and 29-20 in
preparation for removing the injection and production tubulars from these wells and placing
the wells on long term standby. ASLLP anticipates that wells 20-19 and 29-20 will experience a
positive balance until equilibrium is reached.
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