PERMFILE54123

• Permit No: M1999002
• IBM Index Class Name: Permit File
• Doc Date: 6/18/1999
• Doc Name: OBJECTORS EXHIBITS
• Media Type: D
• Archive: No

injection of a fluid such ~r or oil along with fresh water to fora cushion or pad at the top of the
cavem. Soiutioning is th conFned to a controlled height at the om of the cavem until a desired
cavem diameter is attained. Thickness of the cushion is then reduced to allow upward solutioning and
development of a cylindrical cavem. Close control of both height and diameter of the cavem enhances
cavem stability.
In Tully Valley, roof padding using air az the cushion waz first used in 1929 (see Figure 4). The
goals were longer well life and greater ultimate salt recovery without repeated caving and workovers
'. (Trump, 1936). The company did not adhere to Trump's well spacing recommendations (Trump,
undated}, however, and removal of larger volumes of salt from closely-spaced wells in pre-existing
Interconnected caverns further contributed to the creation of large, unsupported roof spans. Air-padding
of +vells without close control of the location and direction of solutioning eventually contributed to the
formation of sinkholes.
'4i'i!d brining. "-Pullen (1973) referred to withdrawal of brine, without the use of injection, as "wild
brining." Brine ++ithdrauT via this method is created by solutioning of subsurface salt by nzturall}~
circulating groundwater. Because most solutioning occurs where fresh water initially contacts the salt,
the location of solutioning is unknown and uncontrolled. The international solution mining industr}'
recognized the subsidence hazard associated with these circumstances and most operators discontinued
the practice by ]921 (Solvay Process Company [Brussels], 1921).
Despite the Solvay Brussels group's recommendation to the contrary, the first intentional use of
wild brining in Tully Valley took place for a short time in 1926, according to Larkin (1950):
In 1926, another study was made to find out if Less water could be used to feed
the +vells as the amount required +vas 40 to 60°o above the theoretical amount, due to
underground losses.
The amount of water fed to the various w~elis was decreased and as the elevation
of the water table fell, it .vas necessary to lengthen the air pipes for the air lifts, and to
increase the air pressure.
The water w•as reduced to a point where less than the theoretical amount was used,
the balance contrtrg from ground r~~ater, but cost for power for compressed air increased
to such an extent that after obtaining the data the old water levels were restored.
~\'ell records indicate that, starting in about 1930, casings were removed from closely spaced
wells in Tully Valley. This allowed aquifer water to flow do++~ through wellbores and dissolve salt,
initiating the process that led to long-term wild brining. As caverns grew, coalesced, and eventually
collapsed due to inadequate roof support, the overlying strata became s:verely fractured. Ground+vater
recharge to the deep salt strata through these fractures z,~d unplugged zbz,~doned wellbores increased to
the extent that by the late 1950's fresh water injection w•as no longer necessan• for sufficient solutioning
to occur (Tully, 1985). Circulating groundwater rather than injectec Eresh water w•as the cause of
solutioning, with the points of fresh water entry to the salt cavern unkne++n and uncontrolled. The Tully
Valley ++ild brining scenario is illustrated in Figure 5. From the late 19>0's through 1986, approximately
one billion gallons of bane per }ear we;e withdrawn with little or no i;tlecnon and no control of the
location or extent of solutioning.
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