GENERAL32022

• Permit No: M1983194
• IBM Index Class Name: General Documents
• Doc Name: COVER SHEET-2 PUBLIC COMMENTS ON DRAFT EIS & RESPONSES TO COMMENTS
• Media Type: D
• Archive: No

2. RESPONSES TO PUBLIC COMMENTS
Response No. 79. BLM is in complete agrcement for
the need to develop a hydrologic model to evaluate salt
loading, transport, and expected impacts from mining
operations. However, BLM has used the best available
information to determine possible impacts to the hydrologic
system at this time.
Water Resources/Geology/Rock Mechanics
Response No. 80. The solution cavity wiB open slowly
with the rate of dissolution of the nahcoGte. The rate of
caving will be proportional to the strength of ground, the
size of opening, and the rate at which the openiug ti made.
The loading to the strata overlying Use solution cavity will
take place slowly, As loading increases, sagging will occw
in this strata, and some delamination of the strata
immediately over the ravines would be expected. The
thermal effect of the process waters on Ute structural integrity
of the overlying strata to the solution cavities is within the
limitation factors established for the caving of these beds.
Over long periods of time, additional svesses may cause
further caving. These svesses, on the character of beds, would
cause caving at slow rates, With caviug, turbulence within
the immediate aquifer could be induced and porosity would
increase, but Ute flow of the aquifer would not necessarily
increase.
The rate of leaching due to cavity collapse is very difficult
to predin and is dependent on the movement of water
through the lower aquifer. With cavity collapse, dissolution
would probably increase; however, the groundwater system
will be monitored to see if there are any impacts.
Groundwater degradation and saline zone leaching retes
were estimated from all available data and were presented
in the EIS to give the reader an approximation of levels
at which impacts were expected to occur. Other government
agencies were consulted for comments and for interpretation
of analysis for subsidence and leaching.
As stated on page 45 of the draft, Section 4.2.2.2, second
column, first paragraph, rapid roof collapse is not exported.
Therefore, rapid leaching is not expected either. However,
extensive monitoring will be implemented to verify the
predictions made in ow analysis.
Only with development of the solution ravines in actual
field conditions can all factors controlling ground stability
be determined and verified. At the same time, monitoring
of the aquifers will be required to detect and quantify impacts.
If the impacts are significant, remedial actions will be taken.
The premise of the environmental impact statement is
the conservation of resowces, both mineral and environ-
mental. The solution mining of the nahcolite within the
Boles Bed presents virtually no risk to the futwe minebiliry
of the oil shale. The minable oil shale would remain virtually
intact, as it is today, and any additional commingling of
the aquifers, than exists today, would not be inherent. The
monitoring and mitigation developed in this document wiB
accomplish this goal.
Water Resources/Rock Mechanics
Response No. 81. The roof span and the pillar width
could be altered m mitigate any unexpected caving of the
cavity.
Response No. 82. Although plan views and cross
sectional fllusvations would be another piece of data, BLM
believes that the text describes the cavities and groundwater
Bow patterns precisely and in sufficient detail for an E[S
document. This is not a technical report.
Well Completion/Operation/Abandonment
Response No. 83. Please refer to Appendix B for BLM's
technical evaluation of WRC's proposed well completion
end abandonment procedwes.
Response No. 84. Since maximum utility from the
minimum allowable cement job is dewed for this project,
a comprehensive evaluation of the cement must occur. [f
necessary, remedial cementing procedures wilt be designed
end executed to enswe adequate cavity isolation and a stable
well bore environment for nabcolite exvaction, The Cement
Evaluation Tool log or equivalent will provide the data
needed to fully evaluate the cement job. A Cement Bond
Log, which does not provide the necessary data, is subject
to well bore effects and is difficult to interpret.
The temperature log does not provide the accuracy
necessary to determine the exact cement top or any
information to determine cement bonding. Please refer to
Appendix B for further clarification on cement bonding
concerns.
Response No. 85. No change.
Oceurtences of gas above the Saline Zone are documented.
The potential for gas to accumulate within the voids left
across the Mahogany Zone exists. There is also the possibility
of water flow through voids across the Mahogany Zone
that are opened during mining operations. Placement of a
cement plug across the Mahogany Zone will maintain its
function as a semiconfining layer to provide isolation of
the upper and lower aquifer, and will also protect i[ for
future recovery of the nth oil shale resource.
Response No. 86. ThissectianexplainsWRC'sproposed
well completion program. Refer to Appendix C for the
mitigating measures that will be applied to the approved
action, regardless of the alternative.
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