| (a) Plans and specifications. Except as specifically
required in the terms of the disposal well permit, construction of
the cavern shall be done in accordance with all permit application
plans and specifications. Any proposed changes to the plans and specifications
must be certified in writing by the executive director that said changes
provide protection standards equivalent to or greater than the original
design criteria.
(b) Standards for bedded salt cavern construction.
(1) The creation of waste disposal caverns within bedded
salt shall be accomplished by the controlled dissolution of the sidewalls
of the well bore to a specified maximum diameter, between selected
elevations specified in the permit as the top and bottom of the injection
interval.
(2) The enlargement of a portion of the original well
bore to serve as the cavern shall be done according to the cavern
construction plans which shall be submitted as a part of the permit
application. The cavern construction plans shall demonstrate at a
minimum, the following:
(A) adjacent caverns shall be separated by a minimum
pillar to cavern diameter ratio of 2.0 to ensure a sufficient amount
of separation for cavern safety and stability;
(B) that cavern dimensions have been designed by a
qualified professional engineer and geologist, to ensure the structural
integrity of the cavern;
(C) if an applicant proposes to conduct solution-mining
activities concurrent with waste disposal, a plan for the controlled
expansion of the cavern;
(D) plans for continual monitoring of the volumes of
materials injected and produced during cavern development and waste
injection;
(E) plans for cavern pressure tests and sonar surveys
to determine the cavern dimensions, volume, geometric shape, and characterization
of anomalies;
(F) the cavern construction process shall be conducted
under the supervision of a qualified professional engineer, with current
registration under the Texas Engineering Practice Act, in accordance
with accepted practices in the cavern construction industry; and
(G) all brines displaced from the cavern shall be managed
and/or disposed of in facilities authorized for such purpose.
(c) Injection tubing. Except for circulation of drilling
fluids during well construction, all injection activities for bedded
salt cavern construction and waste disposal in a bedded salt cavern
shall be performed through removable injection tubing(s) installed
inside the cemented long string casing and extending from the wellhead
at ground surface to the bedded salt cavern below the long string
casing seat.
(d) Logs and Tests.
(1) The permit applicant shall submit, as part of its
construction plan, information identifying the tests which it will
use to verify cavern dimensions. This information shall include at
a minimum, the following:
(A) a description of surveys, logs, and tests to be
run and analyzed, including any quantitative performance standards
appropriate for any such procedure; and
(B) the frequency of such surveys or logs.
(2) Before waste disposal, the integrity of the cavern
shall be tested in accordance with §331.43(b) of this title (relating
to Mechanical Integrity Standards).
(e) Workovers.
(1) The permittee shall notify the executive director
before commencing any workover operation or corrective maintenance
which involves taking the disposal well out of service. The notification
shall be in writing and shall include plans for the proposed work.
The executive director may grant an exception of the prior written
notification when immediate action is required. Approval by the executive
director shall be obtained before the permittee may begin any workover
operation or corrective maintenance that involves taking the well
out of service. Pressure control equipment shall be installed and
maintained during workovers which involve the removal of tubing.
(2) Well mechanical integrity shall be demonstrated
following any major operations which involve removal of the injection
tubing, recompletions, or unseating of the packer. Cavern integrity
demonstration may be required by the executive director in instances
where the integrity of the casing seat or cavern may be compromised.
(f) Reports and approval.
(1) Initial cavern integrity report. The operator shall
submit a report with the results of all tests regarding cavern integrity,
within 30 days of completion of the bedded salt cavern construction
stage.
(2) Notification of completion of the cavern construction
stage. Within 90 days of completion of cavern construction, the permittee
shall provide notification to the executive director which states
that the cavern construction is in compliance with the applicable
provisions of the permit. The permittee shall submit to the executive
director the following reports and certifications prepared and sealed
by a professional engineer with current registration under the Texas
Engineering Practice Act:
(A) final construction, "as-built" plans and specifications,
injection and confining zone data, and an evaluation of the considerations
under §331.45(3) of this title (relating to Executive Director
Approval of Construction and Completion);
(B) certification that the construction of the cavern
has been completed in accordance with the provisions of the disposal
well permit and with the design and construction specifications of
the permittee's application;
(C) certification that actual confining and injection
zone data obtained will not result in need for a change in the operating
parameters specified in the permit; and
(D) certification that the bedded salt cavern injection
zone will not be in or above a formation which within 1/4 mile of
the bedded salt cavern injection zone contains an underground source
of drinking water.
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