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
three season monitoring effort will help ensure reclamation
success, providing a strongly established, self-sustaining
vegetation community that mcets stated pastmine land goals.
Bock Quality/Mechanics
Response No. 38. Please see the TEXT CHANGES
section for page 45 of the draft. A discussion on the area
of collapse was added For clarity.
Response No. 39. Production of a cavity will be stopped
when the calculated volume of the clrrty has bees produced.
This will insure that the total pillar area will remain in
place. Actual cavity configttretion will be monitored using
stateof-the-art methods az approvtxl by the authorized
officer.
Subsidence
Response No. 45. Substantial subsidence has oceurted
because of the natural dissolution process within the basin.
Any additions{ subsidence from WRC's proposal would
only be incidental by comparison. Small additional
movement to the identified minable zone in the Mahogany
would not render it less minable than it exists today. If
subsidence monitoring indicates significant impacts
developing, lben mitigation will be imposed on WRC to
reduce these impacts (i.e., larger pillars between cavities,
backfilling cavities, etc.) and bring the project into
compliance with lease requirements.
Subsidence Monitoring
The pillars have been designed based on accepted strength
tests for the nahcohte material. Summarizing these tests is
beyond the scope of this EIS.
Response No. 40. No change is necrssary. The strata
immediately overlying the cavities, including the lower
leached zone, contains varying degrees of rock quality. Any
caving and/or fracturing would significantly reduce the
existing rack quality.
Response No. 4!. No change is necessary. This section
is an impact summarization and the sentence is correct az
stated.
Rubber Beds
Response No. 41. BLM concurs with EPA on their
concerns on the effectiveness of the ntbber beds; therefore,
subsur[ace subsidence of the solution cavity will be
monitored during the pilot phase.
Stratlgraphy
Response No. 43. No change. Figure 3-IA is a
generalized, svatigraptuc column and was used to give the
reader a general idea of where the oil shrde zones and aquifers
are located. Inclusion of additional, site-specific profdes were
not deemed necessary or appropriate for the purposes of
this document. However, more detailed information is
available for review at the White River Resource Area office.
Response No. 44. BLM does not refer to this entire
section from the dissolution surface to the top of the R-
8 azthe leached zone. However, we do agree that leaching
of sodium minerals has occurred in the upper Mahogany
and R-8 zones, although not to the same degree az in the
lower Mahogany down to the dissolution surface.
Response No. 46. Mulliplepointboreholeextensometers
are of different types and are available through several
suppliers. Wves or rods are extended down the borehole
in tubes or sheath. The down-hole end is anchored at the
dewed elevation, using a hydraulic or grout anchor to the
borehole wall. The surface end is tensioned, and any
movement in the hole at point of anchorage can be measured
mechanically or electrically.
Multiple point borehole extensomelers will be used to
measure any deflections from the solution cavity up to the
Mahogany Zone. It is the Mahogany Zone which is of
concern and will be monitored. The upper Mahogany Zone
is a semiconfining layer between the two aquifer systems
and must be protected from excessive movement and
fracture. WRC must submit a subsidence monitoring plan
with location of surface monuments, subsidence monitoring
drill holes, and their design and installation procedures for
approval prior to mining operations.
Surface Disltrrbarrce
Response No. 47. Yes, we agree with your statement.
That is why, as stated in the first sentence of the referenced
paragraph, such impacts are not considered significant. No
change necessary.
Response No. 48. BLM's goal in relationship to W RC's
proposed well field development is to minimize surface
disturbance and to facilitate successful reclamation of
disturbed lands. Because of the lack of concise, detailed
plans on specific well field mechanics and development,
the analysis in the draft EIS considers and depicts the entire
delineated well field az being potentially disturbed. However,
based on the limited information in-hand, it appears that
only 70 percent of the actual delineated well field area would
be physically disturbed under any of the commercial-scale
alternatives, assuming 300-foot spacing between well pairs.
Assuming 600-foot well spacing, this figure is expected to
drop to 40 percent.
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