Notice2025-23804
McNally Tunneling Corp./ASI Marine Southerly Tunnel and Consolidation Project: Grant of Permanent Variance
Primary source
Metadata and text below are from the Federal Register, a public-domain U.S. government work. Always verify the official published version before relying on it for any legal matter.
Published
December 29, 2025
Effective
December 29, 2025
Issuing agencies
Labor DepartmentOccupational Safety and Health Administration
Abstract
In this notice, OSHA grants a permanent variance to McNally Tunneling Corp./ASI Marine (McNally/ASI Marine) related to work in compressed-air environments.
Full Text
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<title>Federal Register, Volume 90 Issue 245 (Monday, December 29, 2025)</title>
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[Federal Register Volume 90, Number 245 (Monday, December 29, 2025)]
[Notices]
[Pages 60752-60762]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2025-23804]
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DEPARTMENT OF LABOR
Occupational Safety and Health Administration
[Docket No. OSHA-2025-0004]
McNally Tunneling Corp./ASI Marine Southerly Tunnel and
Consolidation Project: Grant of Permanent Variance
AGENCY: Occupational Safety and Health Administration (OSHA), Labor.
ACTION: Notice.
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SUMMARY: In this notice, OSHA grants a permanent variance to McNally
Tunneling Corp./ASI Marine (McNally/ASI Marine) related to work in
compressed-air environments.
DATES: The permanent variance specified by this notice becomes
effective on December 29, 2025 and shall remain in effect until the
completion of the Southerly Tunnel and Consolidation project or until
modified or revoked by OSHA.
FOR FURTHER INFORMATION CONTACT: Information regarding this notice is
available from the following sources:
Press inquiries: Contact Mr. Frank Meilinger, Director, OSHA Office
of Communications, phone: (202) 693-1999; email:
<a href="/cdn-cgi/l/email-protection#c8a5ada1a4a1a6afadbae6aebaa9a6aba1bbfa88aca7a4e6afa7be"><span class="__cf_email__" data-cfemail="9ff2faf6f3f6f1f8faedb1f9edfef1fcf6ecaddffbf0f3b1f8f0e9">[email protected]</span></a>.
General and Technical Information: Contact Kevin Robinson,
Director, Office of Technical Programs and Coordination Activities,
Directorate of Technical Support and Emergency Management, Occupational
Safety and Health Administration, U.S. Department of Labor; phone:
(202) 693-1911 or email: <a href="/cdn-cgi/l/email-protection#73011c111a1d001c1d5d1816051a1d33171c1f5d141c05"><span class="__cf_email__" data-cfemail="f78598959e99849899d99c92819e99b793989bd9909881">[email protected]</span></a>.
SUPPLEMENTARY INFORMATION:
Copies of this Federal Register notice: Electronic copies of this
Federal Register notice are available at <a href="http://www.regulations.gov">http://www.regulations.gov</a>.
This Federal Register notice and other relevant information are also
available at OSHA's web page at <a href="http://www.osha.gov">http://www.osha.gov</a>.
I. Overview
On July 16, 2024, OSHA received a variance application submitted by
letter from McNally Tunneling Corp./ASI (McNally/ASI Marine or the
applicant) submitted under Section 6(d) of the Occupational Safety and
Health Act of 1970 (the Act), 29 U.S.C. 655, and 29 CFR 1905.11
(Variances and other relief under Section 6(d)) an application for a
permanent variance from several provisions of the OSHA standard that
regulates work in compressed air, 1926.803 of 1926 Subpart S--
Underground Construction, Caissons, Cofferdams, and Compressed Air, and
an interim order allowing it to proceed while OSHA considers the
request for a permanent variance This notice addresses McNally/ASI
Marine's application for a permanent variance and interim order for
construction of Southerly Tunnel and Consolidation Project in
Cleveland, Ohio, only and is not applicable to future McNally/ASI
Marine tunneling projects.
Specifically, McNally/ASI Marine sought a variance from the
provisions of the standard that: (1) prohibit compressed-air worker
exposure to pressures exceeding 50 pounds per square inch (p.s.i.)
except in an emergency (29 CFR 1926.803(e)(5)); \1\ (2) require the use
of the decompression values specified in decompression tables in
Appendix A of the compressed-air standard for construction (29 CFR
1926.803(f)(1)); and (3) require the use of automated operational
controls and a special decompression chamber (29 CFR
1926.803(g)(1)(iii) and .803(g)(1)(xvii), respectively). McNally/ASI
Marine also requested an interim order pending OSHA's decision on the
application for a variance (Document ID No. OSHA-2025-0004-0002).
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\1\ The decompression tables in Appendix A of subpart S express
the maximum working pressures as pounds per square inch gauge
(p.s.i.g.), with a maximum working pressure of 50 p.s.i.g.
Therefore, throughout this notice, OSHA expresses the 50 p.s.i.
value specified by 29 CFR 1926.803(e)(5) as 50 p.s.i.g., consistent
with the terminology in Appendix A, Table 1 of subpart S.
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OSHA reviewed McNally/ASI Marine's application for a permanent
variance and interim order and determined that it was appropriately
submitted in compliance with the applicable variance procedures in
Section 6(d) of the Occupational Safety and Health Act of 1970 (OSH
Act; 29 U.S.C. 655) and OSHA's regulations at 29 CFR 1905.11 (variances
and other relief under section 6(d)).
OSHA reviewed the alternative procedures in McNally/ASI Marine's
application and preliminarily determined that the applicant's proposed
alternatives on the whole, subject to the conditions in the request and
imposed by the interim order, provide measures that are as safe and
healthful as those required by the cited OSHA standards. On July 24,
2025, OSHA published a Federal Register notice announcing McNally/ASI
Marine's application for permanent variance, stating the preliminary
determination along with the basis of that determination, and granting
the interim order (90 FR 34887). OSHA requested comments on each.
OSHA did not receive any comments or other information disputing
the preliminary determination that the alternatives were at least as
safe as OSHA's standard, nor any objections to OSHA granting a
permanent variance. Accordingly, through this notice OSHA grants a
permanent variance, subject to the conditions set out in this document.
A. Background
The information that follows about McNally/ASI Marine, its methods,
and its project comes from McNally/ASI Marine's variance application.
McNally/ASI Marine is a contractor for the Southerly Tunnel and
Consolidation Project (the project), that works on complex tunnel
projects using innovations in tunnel-excavation methods. The
applicant's workers engage in the construction of tunnels using
advanced shielded mechanical excavation techniques in conjunction with
an earth pressure balanced micro-tunnel boring machine (TBM). Using
shielded mechanical excavation techniques, in conjunction with precast
concrete tunnel liners and backfill grout, TBMs provide methods to
achieve the face pressures required to maintain a stabilized tunnel
face through various geologies and isolate that pressure to the forward
section (the working chamber) of the TBM.
McNally/ASI Marine asserts that it bores tunnels using a TBM at
levels below the water table through soft soils
[[Page 60753]]
consisting of clay, silt, and sand. TBMs are capable of maintaining
pressure at the tunnel face, and stabilizing existing geological
conditions, through the controlled use of a mechanically driven cutter
head, bulkheads within the shield, ground-treatment foam, and a screw
conveyor that moves excavated material from the working chamber. The
forward-most portion of the TBM is the working chamber, and this
chamber is the only pressurized segment of the TBM. Within the shield,
the working chamber consists of two sections: the forward working
chamber and the staging chamber. The forward working chamber is
immediately behind the cutter head and tunnel face. The staging chamber
is behind the forward working chamber and between the man-lock door and
the entry door to the forward working chamber.
The TBM has twin man-locks located between the pressurized working
chamber and the non-pressurized portion of the machine. Each man-lock
has two compartments. This configuration allows workers to access the
man-locks for compression and decompression, and medical personnel to
access the man-locks if required in an emergency.
McNally/ASI Marine's Hyberbaric Operations Manual (HOM) for the
Southerly Tunnel and Consolidation Project indicates that the maximum
pressure to which it is likely to expose workers during project
interventions for the Southerly Tunnel and Consolidation Project is 58
p.s.i. Therefore, to work effectively, McNally/ASI Marine must perform
hyperbaric interventions in compressed air at pressures nearly 20%
higher than the maximum pressure specified by the existing OSHA
standard, 29 CFR 1926.803(e)(5), which states: ``No employee shall be
subjected to pressure exceeding 50 p.s.i. except in emergency'' (see
footnote 1).
McNally/ASI Marine employs specially trained personnel for the
construction of the tunnel. To keep the machinery working effectively,
McNally/ASI Marine asserts that these workers must periodically enter
the excavation working chamber of the TBM to perform hyperbaric
interventions during which workers would be exposed to air pressures up
to 58 p.s.i., which exceeds the maximum pressure specified by the
existing OSHA standard at 29 CFR 1926.803(e)(5). These interventions
consist of conducting inspections or maintenance work on the cutter-
head structure and cutting tools of the TBM, such as changing
replaceable cutting tools and disposable wear bars, and, in rare cases,
repairing structural damage to the cutter head. These interventions are
the only time that workers are exposed to compressed air. Interventions
in the working chamber (the pressurized portion of the TBM) take place
only after halting tunnel excavation and preparing the machine and crew
for an intervention.
During interventions, workers enter the working chamber through one
of the twin man-locks that open into the staging chamber. To reach the
forward part of the working chamber, workers pass through a door in a
bulkhead that separates the staging chamber from the forward working
chamber. The man-locks and the working chamber are designed to
accommodate three people, which is the maximum crew size allowed under
the permanent variance. When the required decompression times are
greater than work times, the twin man-locks allow for crew rotation.
During crew rotation, one crew can be compressing or decompressing
while the second crew is working. Therefore, the working crew always
has an unoccupied man-lock at its disposal.
McNally/ASI Marine asserts that these innovations in tunnel
excavation have greatly reduced worker exposure to hazards of
pressurized air work because they have eliminated the need to
pressurize the entire tunnel for the project and would thereby reduce
the number of workers exposed, as well as the total duration of
exposure, to hyperbaric pressure during tunnel construction. These
advances in technology substantially modified the methods used by the
construction industry to excavate subaqueous tunnels compared to the
caisson work regulated by the current OSHA compressed-air standard for
construction at 29 CFR 1926.803.
In addition to the reduced exposures resulting from the innovations
in tunnel-excavation methods, McNally/ASI Marine asserts that
innovations in hyperbaric medicine and technology improve the safety of
decompression from hyperbaric exposures. These procedures, however,
would deviate from the decompression process that OSHA requires for
construction in 29 CFR 1926.803(e)(5) and (f)(1) and the decompression
tables in Appendix A of 29 CFR 1926, subpart S. Nevertheless, according
to McNally/ASI Marine, their use of decompression protocols
incorporating oxygen is more efficient, effective, and safer for tunnel
workers than compliance with the decompression tables specified by the
existing OSHA standard.
McNally/ASI Marine contends that the alternative safety measures
included in the application provide McNally/ASI Maine's workers with a
place of employment that is at least as safe under its proposed
alternatives as they would be under OSHA's compressed-air standard for
construction. McNally/ASI Marine also provided OSHA a project-specific
HOM, (OSHA-2025-0004-0003) that requires specialized medical support
and hyperbaric supervision to provide assistance to a team of specially
trained man-lock attendants and hyperbaric or compressed-air workers to
support their assertions of equivalency in worker protection.
OSHA included all of the above information in the Federal Register
notice regarding McNally/ASI Marine's variance application and did not
receive any comments disputing any of that information, including the
safety assertions made by McNally/ASI Marine in the variance
application.
II. The Variance Application
Pursuant to the requirements of OSHA's variance regulations (29 CFR
1905.11), the applicant has certified that it notified its workers \2\
of the variance application and request for interim order by posting,
at prominent locations where it normally posts workplace notices, a
summary of the application and information specifying where the workers
can examine a copy of the application. In addition, the applicant has
certified that it informed its workers of their right to petition the
Assistant Secretary of Labor for Occupational Safety and Health for a
hearing on the variance modification application.
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\2\ See the definition of ``Affected employee or worker'' in
section VII.C. of this Notice.
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III. OSHA History of Approval of Nearly Identical Variance Requests
OSHA has previously approved several nearly identical variances
involving the same types of tunneling equipment used for similar
projects (tunnel construction variances). OSHA notes that it granted
several subaqueous tunnel construction permanent variances from the
same provisions of OSHA's compressed-air standard (29 CFR
1926.803(e)(5), (f)(1), (g)(1)(iii), and (g)(1)(xvii)) that are the
subject of the present application: (1) Impregilo, Healy, Parsons,
Joint Venture (IHP JV) for the Anacostia River Tunnel in Washington, DC
(80 FR 50652, August 20, 2015); (2) Traylor JV for the Blue Plains
Tunnel in Washington, DC (80 FR 16440, March 27, 2015); (3) Tully/OHL
USA Joint Venture for the New York Economic Development Corporation's
New York Siphon Tunnel project (79 FR 29809, May 23, 2014); (4) Salini-
Impregilo/Healy Joint Venture for the Northeast Boundary Tunnel in
[[Page 60754]]
Washington, DC (85 FR 27767, May 11, 2020); (5) McNally/Kiewit SST for
the Shoreline Storage Tunnel in Cleveland, Ohio (88 FR 15080, March 10,
2023); (6) Traylor Shea Joint Venture for the Alexandria RiverRenew
Tunnel Project in Alexandria, Virginia and Washington, DC (88 FR 15090,
March 10, 2023); (7) Traylor-Sundt Joint Venture, for the Integrated
Pipeline Tunnel Project in Dallas, Texas (88 FR 83152, November 28,
2023); (8) Ballard Marine Construction for the Bay Park Conveyance
Tunnel Project in Nassau County, New York (89 FR 8442, February 7,
2024); and (9) Ballard Marine Construction for the Lower Olentangy
Tunnel Project in Columbus, Ohio (89 FR 78906, September 26, 2024).
OSHA also granted interim orders to Ballard Marine Construction for the
Suffolk County, New York Outfall Tunnel Project (86 FR 5253, January
19, 2021) and CBNA/Halmar Joint Venture (90 FR 34902, July 24, 2025) in
addition to the interim order granted for this project. The proposed
alternate conditions in this notice are nearly identical to the
alternate conditions of the previous permanent variances. OSHA is not
aware of any injuries or other safety issues that arose from work
performed under these conditions in accordance with the previous
variances.
IV. Applicable OSHA Standard and the Relevant Variance
A. Variance From Paragraph (e)(5) of 29 CFR 1926.803, Prohibition of
Exposure to Pressure Greater Than 50 p.s.i.g. (see footnote 1)
The applicant states that it may perform hyperbaric interventions
at pressures up to 58 p.s.i.g. in the working chamber of the TBM; this
pressure exceeds the pressure limit of 50 p.s.i. specified for
nonemergency purposes by 29 CFR 1926.803(e)(5). The TBM has twin man-
locks, with each man-lock having two compartments. This configuration
allows workers to access the man-locks for compression and
decompression, and medical personnel to access the man-locks if
required in an emergency.
TBMs are capable of maintaining pressure at the tunnel face, and
stabilizing existing geological conditions, through the controlled use
of a mechanically driven cutter head, bulkheads within the shield,
ground-treatment foam, and a screw conveyor that moves excavated
material from the working chamber. As noted earlier, the forward-most
portion of the TBM is the working chamber, and this chamber is the only
pressurized segment of the TBM. Within the shield, the working chamber
consists of two sections: the staging chamber and the forward working
chamber. The staging chamber is the section of the working chamber
between the man-lock door and the entry door to the forward working
chamber. The forward working chamber is immediately behind the cutter
head and tunnel face.
McNally/ASI Marine will pressurize the working chamber to the level
required to maintain a stable tunnel face. Pressure in the staging
chamber ranges from atmospheric (no increased pressure) to a maximum
pressure equal to the pressure in the working chamber. The applicant
asserts that they may have to perform interventions at pressures up to
58 p.s.i.
During interventions, workers enter the working chamber through one
of the twin man-locks that open into the staging chamber. To reach the
forward part of the working chamber, workers pass through a door in a
bulkhead that separates the staging chamber from the forward working
chamber. The maximum crew size allowed in the forward working chamber
is three. At certain hyperbaric pressures (i.e., when decompression
times are greater than work times), the twin man-locks allow for crew
rotation. During crew rotation, one crew can be compressing or
decompressing while the second crew is working. Therefore, the working
crew always has an unoccupied man-lock at its disposal.
Further, McNally/ASI Marine has developed a project-specific HOM
(OSHA-2025-0004-0003) that describes in detail the hyperbaric
procedures, the required medical examination used during the tunnel-
construction project, the standard operating procedures and the
emergency and contingency procedures. The procedures include using
experienced and knowledgeable man-lock attendants who have the training
and experience necessary to recognize and treat decompression illnesses
and injuries. The attendants are under the direct supervision of the
hyperbaric supervisor (a competent person experienced and trained in
hyperbaric operations, procedures and safety) and attending physician.
In addition, procedures include medical screening and review of
prospective compressed-air workers (CAWs). The purpose of this
screening procedure is to vet prospective CAWs with medical conditions
(e.g., deep vein thrombosis, poor vascular circulation, and muscle
cramping) that could be aggravated by sitting in a cramped space (e.g.,
a man-lock) for extended periods, or by exposure to elevated pressures
and compressed gas mixtures. A transportable recompression chamber
(shuttle) is available to extract workers from the hyperbaric working
chamber for emergency evacuation and medical treatment; the shuttle
attaches to the topside medical lock, which is a large recompression
chamber. The applicant believes that the procedures included in the HOM
provide safe work conditions when interventions are necessary,
including interventions above 50 p.s.i. or 50 p.s.i.g.
OSHA comprehensively reviewed the project-specific HOM and
determined that the safety and health instructions and measures it
specifies are appropriate, conform with the conditions in the variance,
and adequately protect the safety and health of the CAWs.
B. Variance From Paragraph (f)(1) of 29 CFR 1926.803, Requirement To
Use OSHA Decompression Tables
OSHA's compressed-air standard for construction requires
decompression in accordance with the decompression tables in Appendix A
of 29 CFR 1926, subpart S (29 CFR 1926.803(f)(1)). As an alternative to
the OSHA decompression tables, the applicant proposes to use newer
decompression schedules (the 1992 French Decompression Tables) that
rely on staged decompression and supplement breathing air used during
decompression with air or oxygen (as appropriate).\3\ The applicant
asserts decompression protocols using the 1992 French Decompression
Tables for air or oxygen as specified by the Southerly Tunnel and
Consolidation Project-specific Hyperbaric Operations Manual (HOM) are
safer for tunnel workers than the decompression protocols specified in
Appendix A of 29 CFR 1926, subpart S. Accordingly, the applicant
commits to following the decompression procedures described in that
HOM, which would require it to follow the 1992 French Decompression
Tables to decompress CAWs after they exit the hyperbaric conditions in
the working chamber.
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\3\ In 1992, the French Ministry of Labour replaced the 1974
French Decompression Tables with the 1992 French Decompression
Tables, which differ from OSHA's decompression tables in Appendix A
by using: (1) staged decompression as opposed to continuous (linear)
decompression; (2) decompression tables based on air or both air and
pure oxygen; and (3) emergency tables when unexpected exposure times
occur (up to 30 minutes above the maximum allowed working time).
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Depending on the maximum working pressure and exposure times, the
1992 French Decompression Tables provide for air decompression with or
without oxygen. McNally/ASI Marine asserts that oxygen decompression
has many
[[Page 60755]]
benefits, including (1) keeping the partial pressure of nitrogen in the
lungs as low as possible; (2) keeping external pressure as low as
possible to reduce the formation of bubbles in the blood; (3) removing
nitrogen from the lungs and arterial blood and increasing the rate of
nitrogen elimination; (4) improving the quality of breathing during
decompression stops so that workers are less tired and to prevent bone
necrosis; (5) reducing decompression time by about 33 percent as
compared to air decompression; and (6) reducing inflammation.
In addition, the project-specific HOM requires a physician,
certified in hyperbaric medicine, to manage the medical condition of
CAWs during hyperbaric exposures and decompression. A trained and
experienced man-lock attendant also will be present during hyperbaric
exposures and decompression. This man-lock attendant will operate the
hyperbaric system to ensure compliance with the specified decompression
table. A hyperbaric supervisor, trained in hyperbaric operations,
procedures, and safety, directly oversees all hyperbaric interventions,
and ensures that staff follow the procedures delineated in the HOM or
by the attending physician.
C. Variance From Paragraph (g)(1)(iii) of 29 CFR 1926.803,
Automatically Regulated Continuous Decompression
McNally/ASI Marine seeks a permanent variance from the OSHA
standard at 29 CFR 1926.803(g)(1)(iii), which requires automatic
controls to regulate decompression. As noted above, the applicant is
committed to conducting the staged decompression according to the 1992
French Decompression Tables under the direct control of the trained
man-lock attendant and under the oversight of the hyperbaric
supervisor.
Breathing air under hyperbaric conditions increases the amount of
nitrogen gas dissolves in a CAW's tissues. The greater the hyperbaric
pressure under these conditions and the more time spent under the
increased pressure, the greater the amount of nitrogen gas dissolved in
the tissues. When the pressure decreases during decompression, tissues
release the dissolved nitrogen gas into the blood system, which then
carries the nitrogen gas to the lungs for elimination through
exhalation. Releasing hyperbaric pressure too rapidly during
decompression can increase the size of the bubbles formed by nitrogen
gas in the blood system, resulting in decompression illness (DCI),
commonly referred to as ``the bends.'' This description of the etiology
of DCI is consistent with current scientific theory and research on the
issue (see footnote 16 in this notice discussing a 1985 NIOSH report on
DCI).
The 1992 French Decompression Tables proposed for use by the
applicant provide for stops during worker decompression (i.e., staged
decompression) to control the release of nitrogen gas from tissues into
the blood system. Studies show that staged decompression, in
combination with other features of the 1992 French Decompression Tables
such as the use of oxygen, result in a lower incidence of DCI than the
use of automatically regulated continuous decompression.\4\ In
addition, the applicant asserts that staged decompression administered
in accordance with its HOM is at least as effective as an automatic
controller in regulating the decompression process because the HOM
includes a hyperbaric supervisor who directly supervises all hyperbaric
interventions and ensures that the man-lock attendant, who is a
competent person in the manual control of hyperbaric systems, follows
the schedule specified in the decompression tables, including stops.
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\4\ See, e.g., Dr. Eric Kindwall, EP (1997), Compressed air
tunneling and caisson work decompression procedures: development,
problems, and solutions. Undersea and Hyperbaric Medicine, 24(4),
pp. 337-345. This article reported 60 treated cases of DCI among
4,168 exposures between 19 and 31 p.s.i.g. over a 51-week contract
period, for a DCI incidence of 1.44% for the decompression tables
specified by the OSHA standard. Dr. Kindwall notes that the use of
automatically regulated continuous decompression for compressed-air
work was in some cases at the insistence of contractors and the
union, and against the advice of the expert who calculated the
decompression table and recommended using staged decompression. Dr.
Kindwall then states, ``Continuous decompression is inefficient and
wasteful. For example, if the last stage from 4 p.s.i.g. . . . to
the surface took 1h, at least half the time is spent at pressures
less than 2 p.s.i.g. . . . , which provides less and less meaningful
bubble suppression. . . .'' In addition, Dr. Kindwall addresses the
continuous-decompression protocol in the OSHA compressed-air
standard for construction, noting that ``[a]side from the tables for
saturation diving to deep depths, no other widely used or officially
approved diving decompression tables use straight line, continuous
decompressions at varying rates. Stage decompression is usually the
rule, since it is simpler to control.''
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D. Variance From Paragraph (g)(1)(xvii) of 29 CFR 1926.803, Requirement
of Special Decompression Chamber
The OSHA compressed-air standard for construction requires
employers to use a special decompression chamber of sufficient size to
accommodate all CAWs being decompressed at the end of the shift when
total decompression time exceeds 75 minutes (see 29 CFR
1926.803(g)(1)(xvii)). Use of the special decompression chamber enables
CAWs to move about and flex their joints to prevent neuromuscular
problems during decompression.
Space limitations in the TBM do not allow for the installation and
use of an additional special decompression lock or chamber. The
applicant proposes that it be permitted to rely on the man-locks and
staging chamber in lieu of adding a separate, special decompression
chamber. Because only a few workers out of the entire crew are exposed
to hyperbaric pressure, the man-locks (which, as noted earlier, connect
directly to the working chamber) and the staging chamber are of
sufficient size to accommodate all exposed workers during
decompression. The applicant uses the existing man-locks, each of which
adequately accommodates a three-member crew for this purpose when
decompression lasts up to 75 minutes. When decompression exceeds 75
minutes, crews can open the door connecting the two compartments in
each man-lock (during decompression stops) or exit the man-lock and
move into the staging chamber where additional space is available. The
applicant asserts that this alternative arrangement is as effective as
a special decompression chamber in that it has sufficient space for all
the CAWs at the end of a shift and enables the CAWs to move about and
flex their joints to prevent neuromuscular problems.
V. Decision
After reviewing the proposed alternatives, OSHA has determined that
the applicant's proposed alternatives on the whole, subject to the
conditions in the variance request and imposed by this permanent
variance, provide measures that are as safe and healthful as those
required by the cited OSHA standards addressed in section IV of this
notice.
In addition, OSHA has determined that each of the following
alternatives are at least as effective as the specified OSHA
requirements:
A. 29 CFR 1926.803(e)(5)
McNally/ASI Marine has developed, and proposed to implement,
effective alternative measures to the prohibition of using compressed
air under hyperbaric conditions exceeding 50 p.s.i. The alternative
measures include use of engineering and administrative controls of the
hazards associated with work performed in compressed-air conditions
exceeding 50 p.s.i. while engaged in the construction of a subaqueous
tunnel using advance shielded mechanical-excavation techniques in
conjunction with the TBM. Prior to conducting interventions
[[Page 60756]]
in the TBM's pressurized working chamber, McNally/ASI Marine halts
tunnel excavation and prepares the machine and crew to conduct the
interventions. Interventions involve inspection, maintenance, or repair
of the mechanical-excavation components located in the working chamber.
B. 29 CFR 1926.803(f)(1)
The applicant has proposed to implement equally effective
alternative measures to the requirement in 29 CFR 1926.803(f)(1) for
compliance with OSHA's decompression tables. The HOM specifies the
procedures and personnel qualifications for performing work safely
during the compression and decompression phases of interventions. The
HOM also specifies the decompression tables the applicant proposes to
use (the 1992 French Decompression Tables). Depending on the maximum
working pressure and exposure times during the interventions, the
tables provide for decompression using air, pure oxygen, or a
combination of air and oxygen. The decompression tables also include
delays or stops for various time intervals at different pressure levels
during the transition to atmospheric pressure (i.e., staged
decompression). In all cases, a physician certified in hyperbaric
medicine will manage the medical condition of CAWs during
decompression. In addition, a trained and experienced man-lock
attendant, experienced in recognizing decompression sickness or
illnesses and injuries, will be present. Of key importance, a
hyperbaric supervisor, trained in hyperbaric operations, procedures,
and safety, will directly supervise all hyperbaric operations to ensure
compliance with the procedures delineated in the project-specific HOM
or by the attending physician.
Prior to granting the previous permanent variances to IHP JV,
Traylor JV, Tully JV, Salini-Impregilo Joint Venture, McNally/Kiewit,
Traylor-Shea, Traylor-Sundt and Ballard, OSHA conducted a review of the
scientific literature and concluded that the alternative decompression
method (i.e., the 1992 French Decompression Tables) McNally/ASI Marine
proposed would be at least as safe as the decompression tables
specified by OSHA when applied by trained medical personnel under the
conditions outlined in this variance application.
Some of the literature indicates that the alternative decompression
method may be safer, concluding that decompression performed in
accordance with these tables resulted in a lower occurrence of DCI than
decompression conducted in accordance with the decompression tables
specified by the standard. For example, H. L. Andersen studied the
occurrence of DCI at maximum hyperbaric pressures ranging from 4
p.s.i.g. to 43 p.s.i.g. during construction of the Great Belt Tunnel in
Denmark (1992-1996).\5\ This project used the 1992 French Decompression
Tables to decompress the workers during part of the construction.
Andersen observed 6 DCI cases out of 7,220 decompression events and
reported that switching to the 1992 French Decompression tables reduced
the DCI incidence to 0.08% compared to a previous incidence rate of
0.14%. The DCI incidence in the study by H. L. Andersen is
substantially less than the DCI incidence reported for the
decompression tables specified in Appendix A.
---------------------------------------------------------------------------
\5\ Anderson HL (2002). Decompression sickness during
construction of the Great Belt tunnel, Denmark.
---------------------------------------------------------------------------
OSHA found no studies in which the DCI incidence reported for the
1992 French Decompression Tables were higher than the DCI incidence
reported for the OSHA decompression tables.\6\
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\6\ Le P[eacute]chon JC, Barre P, Baud JP, Ollivier F (September
1996). Compressed air work--French Tables 1992--operational results.
JCLP Hyperbarie Paris, Centre Medical Subaquatique Interentreprise,
Marseille: Communication a l'EUBS, pp. 1-5 (see Ex. OSHA-2012-0036-
0005).
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OSHA's experience with the previous variances, which all
incorporated nearly identical decompression plans and did not result in
safety issues, also provides evidence that the alternative procedure as
a whole is at least as effective for this type of tunneling project as
compliance with OSHA's decompression tables. The experience of State
Plans \7\ that either granted variances (Nevada, Oregon and Washington)
\8\ or promulgated a new standard (California) \9\ for hyperbaric
exposures occurring during similar subaqueous tunnel-construction work,
provide additional evidence of the effectiveness of this alternative
procedure.
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\7\ Section 18 of the OSH Act, Congress expressly provides that
States and U.S. territories may adopt, with Federal approval, a plan
for the development and enforcement of occupational safety and
health standards. OSHA refers to such States and territories as
``State Plans.'' Occupational safety and health standards developed
by State Plans must be at least as effective in providing safe and
healthful employment and places of employment as the Federal
standards (29 U.S.C. 667).
\8\ These state variances are available in the docket for the
2015 Traylor JV variance: Exs. OSHA-2012-0035-0006 (Nevada), OSHA-
2012-0035-0005 (Oregon), and OSHA-2012-0035-0004 (Washington).
\9\ See California Code of Regulations, Title 8, Subchapter 7,
Group 26, Article 154, available at <a href="http://www.dir.ca.gov/title8/sb7g26a154.html">http://www.dir.ca.gov/title8/sb7g26a154.html</a>.
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C. 29 CFR 1926.803(g)(1)(iii)
The applicant developed, and proposed to implement, an equally
effective alternative to 29 CFR 1926.803(g)(1)(iii), which requires the
use of automatic controllers that continuously decrease pressure to
achieve decompression in accordance with the tables specified by the
standard. The applicant's alternative includes using the 1992 French
Decompression Tables for guiding staged decompression to achieve lower
occurrences of DCI, using a trained and competent attendant for
implementing appropriate hyperbaric entry and exit procedures, and
providing a competent hyperbaric supervisor and attending physician
certified in hyperbaric medicine to oversee all hyperbaric operations.
In reaching this preliminary conclusion, OSHA again notes the
experience of previous nearly identical tunneling variances, the
experiences of State Plan States, and a review of the literature and
other information noted earlier.
D. 29 CFR 1926.803(g)(1)(xvii)
The applicant developed, and proposed to implement, an effective
alternative to the use of the special decompression chamber required by
29 CFR 1926.803(g)(1)(xvii). The TBM's man-lock and working chamber
appear to satisfy all of the conditions of the special decompression
chamber, including that they provide sufficient space for the maximum
crew of three CAWs to stand up and move around, and safely accommodate
decompression times exceeding 75 minutes. Therefore, again noting
OSHA's previous experience with nearly identical variances including
the same alternative, OSHA preliminarily determined that the TBM's man-
lock and working chamber function as effectively as the special
decompression chamber required by the standard.
Based on a review of available evidence, the experience of State
Plans that either granted variances (Nevada, Oregon, and Washington)
\10\ or promulgated a new standard (California) \11\ for hyperbaric
exposures occurring during similar subaqueous tunnel-construction work,
and the information provided in the applicant's
[[Page 60757]]
variance application, OSHA is granting the permanent variance.
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\10\ These state variances are available in the docket: Exs.
OSHA-2012-0035-0006 (Nevada), OSHA-2012-0035-0007 (Oregon), and
OSHA-2012-0035-0008 (Washington).
\11\ See California Code of Regulations, Title 8, Subchapter 7,
Group 26, Article 154, available at <a href="http://www.dir.ca.gov/title8/sb7g26a154.html">http://www.dir.ca.gov/title8/sb7g26a154.html</a>.
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Pursuant to Section 6(d) of the Occupational Safety and Health Act
of 1970 (29 U.S.C. 655), and based on the record discussed above, the
agency finds that when the McNally/ASI Marine complies with the
conditions of the following order, the working conditions of the
McNally/ASI Marine's workers are at least as safe and healthful as if
it complied with the working conditions specified by paragraphs (e)(5),
(f)(1), (g)(1)(iii), and (g)(1)(xvii) of 29 CFR 1926.803. Therefore,
McNally/ASI Marine must: (1) comply with the conditions listed below
under ``Conditions Specified for the Permanent Variance'' for the
period between the date of this notice and completion of the Southerly
Tunnel and Consolidation Project; (2) comply fully with all other
applicable provisions of 29 CFR part 1926; and (3) provide a copy of
this Federal Register notice to all employees affected by the
conditions, including the affected employees of other employers, using
the same means it used to inform these employees of the application for
a permanent variance. Additionally, this order will remain in effect
until one of the following conditions occurs: (1) completion of the
Southerly Tunnel and Consolidation Project; or (2) OSHA modifies or
revokes this final order in accordance with 29 CFR 1905.13.
VI. Description of the Conditions Specified for the Permanent Variance
The conditions for the variance are set out in the Order at the end
of this document. This section provides additional detail regarding the
conditions in the Order.
Condition A: Scope
The scope of the permanent variance limits coverage to the work
situations specified under this condition. Clearly defining the scope
of the permanent variance provides McNally/ASI Marine, their employees,
potential future applicants, other stakeholders, the public and OSHA
with necessary information regarding the work situations in which the
permanent variance applies. To the extent that McNally/ASI Marine
exceeds the defined scope of this variance, it will be required to
comply with OSHA's standards. This permanent variance applies only to
McNally/ASI Marine, and only to the remainder of construction work on
the Southerly Tunnel and Consolidation Project.
Condition B: List of Abbreviations
Condition B defines a number of abbreviations used in the permanent
variance. OSHA believes that defining these abbreviations serves to
clarify and standardize their usage, thereby enhancing the applicant's
and their employees' understanding of the conditions specified by the
permanent variance.
Condition C: Definitions
Condition C defines a series of terms, mostly technical terms, used
in the permanent variance to standardize and clarify their meaning.
Defining these terms serves to enhance the applicant's and their
employees' understanding of the conditions specified by the permanent
variance.
Condition D: Safety and Health Practices
This condition requires the applicant to develop and submit to OSHA
an HOM specific to the Southerly Tunnel and Consolidation Project at
least six months before using the TBM for tunneling operations. The
applicant must also submit, at least six months before using the TBM,
proof that the TBM's hyperbaric chambers have been designed,
fabricated, inspected, tested marked, and stamped in accordance with
the requirements of the most recent edition of ASME PVHO-1-Safety
Standards for Pressure Vessels for Human Occupancy). These requirements
ensure that the applicant develops hyperbaric safety and health
procedures suitable for the project.
The submission of the HOM to OSHA enables OSHA to determine that
the specific safety and health instructions and measures it specifies
are appropriate to the field conditions of the tunnel (including
expected geological conditions), conform to the conditions of the
variance, and adequately protect the safety and health of the CAWs. It
also facilitates OSHA's ability to ensure that the applicant is
complying with these instructions and measures. The requirement for
proof of compliance with ASME PVHO-1 is intended to ensure that the
equipment is structurally sound and capable of performing to protect
the safety of the employees exposed to hyperbaric pressure. The
applicant has submitted the HOM and proof of compliance with the most
recent edition of ASME PVHO-1.
Additionally, the condition includes a series of related hazard
prevention and control requirements and methods (e.g., decompression
tables, job hazard analysis (JHA), operations and inspections
checklists, incident investigation, and recording and notification to
OSHA of recordable hyperbaric injuries and illnesses) designed to
ensure the continued effective functioning of the hyperbaric equipment
and operating system.
Condition E: Communication
Condition E requires the applicant to develop and implement an
effective system of information sharing and communication. Effective
information sharing and communication ensures that affected workers
receive updated information regarding any safety-related hazards and
incidents, and corrective actions taken, prior to the start of each
shift. The condition also requires McNally/ASI Marine to ensure that
reliable means of emergency communications are available and maintained
for affected workers and support personnel during hyperbaric
operations. Availability of such reliable means of communications
enables affected workers and support personnel to respond quickly and
effectively to hazardous conditions or emergencies that may develop
during TBM operations.
Condition F: Worker Qualification and Training
This condition requires the applicant to develop and implement an
effective qualification and training program for affected workers. The
condition specifies the factors that an affected worker must know to
perform safely during hyperbaric operations, including how to enter,
work in, and exit from hyperbaric conditions under both normal and
emergency conditions. Having well-trained and qualified workers
performing hyperbaric intervention work ensures that they recognize,
and respond appropriately to, hyperbaric safety and health hazards.
These qualification and training requirements enable affected workers
to cope effectively with emergencies, as well as the discomfort and
physiological effects of hyperbaric exposure, thereby preventing worker
injury, illness, and fatalities.
Paragraph (2)(e) of this condition also requires the applicant to
provide affected workers with information they can use to contact the
appropriate healthcare professionals if they believe they are
developing hyperbaric-related health effects. This requirement provides
for early intervention and treatment of DCI and other health effects
resulting from hyperbaric exposure, thereby reducing the potential
severity of these effects.
[[Page 60758]]
Condition G: Inspections, Tests, and Accident Prevention
Condition G requires the applicant to develop, implement, and
operate a program of frequent and regular inspections of the TBM's
hyperbaric equipment and support systems, and associated work areas.
This condition helps to ensure the safe operation and physical
integrity of the equipment and work areas necessary to conduct
hyperbaric operations. The condition also enhances worker safety by
reducing the risk of hyperbaric-related emergencies.
Paragraph (3) of this condition requires the applicant to document
tests, inspections, corrective actions, and repairs involving the TBM,
and maintain these documents at the job site for the duration of the
job. This requirement provides the applicant with information needed to
schedule tests and inspections to ensure the continued safe operation
of the equipment and systems, and to determine that the actions taken
to correct defects in hyperbaric equipment and systems were
appropriate, prior to returning them to service.
Condition H: Compression and Decompression
This condition requires the applicant to consult with a designated
medical advisor regarding special compression or decompression
procedures appropriate for any unacclimated CAW and then implement the
procedures recommended by the medical advisor. This provision ensures
that the applicant consults with the medical advisor, and involves the
medical advisor in the evaluation, development, and implementation of
compression or decompression protocols appropriate for any CAW
requiring acclimation to the hyperbaric conditions encountered during
TBM operations. Accordingly, CAWs requiring acclimation have an
opportunity to acclimate prior to exposure to these hyperbaric
conditions. OSHA believes this condition will prevent or reduce adverse
reactions among CAWs to the effects of compression or decompression
associated with the intervention work they perform in the TBM.
Condition I: Recordkeeping
Under OSHA's existing recordkeeping requirements in 29 CFR part
1904 regarding Recording and Reporting Occupational Injuries and
Illnesses, the employer must maintain a record of any recordable
injury, illness, or fatality (as defined by 29 CFR part 1904) resulting
from exposure of an employee to hyperbaric conditions by completing the
OSHA Form 301 Incident Report and OSHA Form 300 Log of Work-Related
Injuries and Illnesses. The applicant did not seek a variance from this
standard and therefore McNally/ASI Marine must comply fully with those
requirements.
Examples of important information to include on the OSHA Form 301
Injury and Illness Incident Report (along with the corresponding
question on the form) are:
Q14
<bullet> the task performed;
<bullet> the composition of the gas mixture (e.g., air or oxygen);
<bullet> an estimate of the CAW's workload;
<bullet> the maximum working pressure;
<bullet> temperature in the work and decompression environments;
<bullet> unusual occurrences, if any, during the task or
decompression
Q15
<bullet> time of symptom onset;
<bullet> duration between decompression and onset of symptoms
Q16
<bullet> type and duration of symptoms;
<bullet> a medical summary of the illness or injury
Q17
<bullet> duration of the hyperbaric intervention;
<bullet> possible contributing factors;
<bullet> the number of prior interventions completed by the injured
or ill CAW; and the pressure to which the CAW was exposed during those
interventions.\12\
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\12\ See 29 CFR 1904 Recording and Reporting Occupational
Injuries and Illnesses (<a href="http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=9631">http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=9631</a>); recordkeeping
forms and instructions <a href="https://www.osha.gov/recordkeeping/forms">https://www.osha.gov/recordkeeping/forms</a>.
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Condition I adds additional reporting responsibilities, beyond
those already required by the OSHA rule. McNally/ASI Marine is required
to maintain records of specific factors associated with each hyperbaric
intervention. The information gathered and recorded under this
provision, in concert with the information provided under Condition J
(using OSHA's Form 301 Injury and Illness Incident Report to
investigate and record hyperbaric recordable injuries as defined by 29
CFR 1904.4, 1904.7, and 1904.8-.12), enables McNally/ASI Marine and
OSHA to assess the effectiveness of the permanent variance in
preventing DCI and other hyperbaric-related effects.
Condition J: Notifications
Under the notification condition, the applicant is required, within
specified periods of time, to notify OSHA of: (1) any recordable
injury, illness, in-patient hospitalization, amputation, loss of an
eye, or fatality that occurs as a result of hyperbaric exposures during
TBM operations; (2) provide OSHA a copy of the hyperbaric exposures
incident investigation report (using OSHA Form 301 Injury and Illness
Incident Report) of these events within 24 hours of the incident; (3)
include on OSHA Form 301 Injury and Illness Incident Report information
on the hyperbaric conditions associated with the recordable injury or
illness, the root-cause determination, and preventive and corrective
actions identified and implemented; (4) provide the certification that
affected workers were informed of the incident and the results of the
incident investigation; (5) notify OSHA's Office of Technical Programs
and Coordination Activities (OTPCA) and the Cleveland Ohio OSHA Area
Office within 15 working days should the applicant need to revise the
HOM to accommodate changes in its compressed-air operations that affect
McNally/ASI Marine's ability to comply with the conditions of the
modified permanent variance; and (6) provide OTPCA and the Cleveland
Ohio OSHA Area Office, at the end of the project, with a report
evaluating the effectiveness of the decompression tables.
It should be noted that the requirement for completing and
submitting the hyperbaric exposure-related (recordable) incident
investigation report (OSHA 301 Injury and Illness Incident Report) is
more restrictive than the current recordkeeping requirement of
completing OSHA Form 301 Injury and Illness Incident Report within 7
calendar days of the incident (1904.29(b)(3)). This modified, more
stringent incident investigation and reporting requirement is
restricted to intervention-related hyperbaric (recordable) incidents
only. Providing rapid notification to OSHA is essential because time is
a critical element in OSHA's ability to determine the continued
effectiveness of the variance conditions in preventing hyperbaric
incidents, and the applicant's identification and implementation of
appropriate corrective and preventive actions.
Further, these notification requirements also enable the applicant,
their employees, and OSHA to assess the effectiveness of the modified
permanent variance in providing the requisite level of safety to the
applicant's workers and based on this assessment, whether to revise or
revoke
[[Page 60759]]
the conditions of the modified permanent variance. Timely notification
permits OSHA to take whatever action may be necessary and appropriate
to prevent possible further injuries and illnesses. Providing
notification to employees informs them of the precautions taken by the
applicant to prevent similar incidents in the future.
Additionally, this condition requires the applicant to notify OSHA
if it ceases to do business, has a new address or location for the main
office, or transfers the operations covered by the modified permanent
variance to a successor company. In addition, the condition specifies
that the transfer of the modified permanent variance to a successor
company must be approved by OSHA. These requirements allow OSHA to
communicate effectively with the applicant regarding the status of the
modified permanent variance and expedite the agency's administration
and enforcement of the modified permanent variance. Stipulating that an
applicant is required to have OSHA's approval to transfer a variance to
a successor company provides assurance that the successor company has
knowledge of, and will comply with, the conditions specified by
modified permanent variance, thereby ensuring the safety of workers
involved in performing the operations covered by the modified permanent
variance.
VII. Order
As of the effective date of this final order, OSHA is revoking the
interim order granted to the applicant on July 24, 2025 (90 FR 34887)
and replacing it with a permanent variance order. Note that there are
not any substantive changes in the conditions between the interim order
and this final order.
OSHA issues this final order authorizing McNally/ASI Marine to
comply with the following conditions instead of complying with the
requirements of 29 CFR 1926.803(e)(5), (f)(1), (g)(1)(iii), and
(g)(1)(xvii). These conditions are:
A. Scope
The permanent variance applies only when McNally/ASI Marine stops
the tunnel-boring work, pressurizes the working chamber, and the CAWs
either enter the working chamber to perform an intervention (i.e.,
inspection, maintain, or repair the mechanical-excavation components),
or exit the working chamber after performing interventions.
The permanent variance applies only to work:
1. That occurs in conjunction with construction of the Southerly
Tunnel and Consolidation Project in Cleveland, Ohio, a subaqueous
tunnel constructed using advanced shielded mechanical-excavation
techniques and involving operation of a TBM;
2. In the TBM's forward section (the working chamber) and
associated hyperbaric chambers used to pressurize and decompress
employees entering and exiting the working chamber; and
3. Performed in compliance with all applicable provisions of 29 CFR
1926 except for the requirement specified by 29 CFR 1926.803(e)(5),
(f)(1), (g)(1)(iii), and (g)(1)(xvii).
4. This order will remain in effect until one of the following
conditions occurs: (1) completion of the Southerly Tunnel and
Consolidation Project; or (2) OSHA modifies or revokes this final order
in accordance with 29 CFR 1905.13.
B. List of Abbreviations
Abbreviations used throughout this permanent variance include the
following:
1. CAW--Compressed-air worker
2. CFR--Code of Federal Regulations
3. DCI--Decompression Illness
4. DMT--Diver Medical Technician
5. TBM--Earth Pressure Balanced Micro-Tunnel Boring Machine
6. HOM--Hyperbaric Operations and Safety Manual
7. JHA--Job hazard analysis
8. OSHA--Occupational Safety and Health Administration
9. OTPCA--Office of Technical Programs and Coordination Activities
C. Definitions
The following definitions apply to this permanent variance,
McNally/ASI Marine's project-specific HOM, and all work carried out
under the conditions of this permanent variance.
1. Affected employee or worker--an employee or worker who is
affected by the conditions of this permanent variance, or any one of
his or her authorized representatives. The term ``employee'' has the
meaning defined and used under the Occupational Safety and Health Act
of 1970 (29 U.S.C. 651 et seq.)
2. Atmospheric pressure--the pressure of air at sea level,
generally 14.7 p.s.i.a., 1 atmosphere absolute, or 0 pounds per square
inch gauge (p.s.i.g).
3. Compressed-air worker--an individual who is specially trained
and medically qualified to perform work in a pressurized environment
while breathing air at pressures not exceeding 58 p.s.i.g.
4. Competent person--an individual who is capable of identifying
existing and predictable hazards in the surroundings or working
conditions that are unsanitary, hazardous, or dangerous to employees,
and who has authorization to take prompt corrective measures to
eliminate them.\13\
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\13\ Adapted from 29 CFR 1926.32(f).
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5. Decompression illness (also called decompression sickness or the
bends)--an illness caused by gas bubbles appearing in body compartments
due to a reduction in ambient pressure. Examples of symptoms of
decompression illness include (but are not limited to): joint pain
(also known as the ``bends'' for agonizing pain or the ``niggles'' for
slight pain); areas of bone destruction (termed ``dysbaric
osteonecrosis''); skin disorders (such as cutis marmorata, which causes
a pink marbling of the skin); spinal cord and brain disorders (such as
stroke, paralysis, paresthesia, and bladder dysfunction);
cardiopulmonary disorders, such as shortness of breath; and arterial
gas embolism (gas bubbles in the arteries that block blood flow).\14\
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\14\ See Appendix 10 of ``A Guide to the Work in Compressed Air
Regulations 1996,'' published by the United Kingdom Health and
Safety Executive and available from NIOSH at <a href="http://www.cdc.gov/niosh/docket/archive/pdfs/NIOSH-254/compReg1996.pdf">http://www.cdc.gov/niosh/docket/archive/pdfs/NIOSH-254/compReg1996.pdf</a>.
Note: Health effects associated with hyperbaric intervention,
but not considered symptoms of DCI, can include: barotrauma (direct
damage to air-containing cavities in the body such as ears, sinuses,
and lungs); nitrogen narcosis (reversible alteration in
consciousness that may occur in hyperbaric environments and caused
by the anesthetic effect of certain gases at high pressure); and
oxygen toxicity (a central nervous system condition resulting from
the harmful effects of breathing molecular oxygen (O<INF>2</INF>) at
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elevated partial pressures).
6. Diver Medical Technician--Member of the dive team who is
experienced in first aid.
7. Earth Pressure Balanced Micro-Tunnel Boring Machine--the
machinery used to excavate the tunnel.
8. Hot work--any activity performed in a hazardous location that
may introduce an ignition source into a potentially flammable
atmosphere.\15\
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\15\ Also see 29 CFR 1926.1202 for examples of hot work.
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9. Hyperbaric--at a higher pressure than atmospheric pressure.
10. Hyperbaric intervention--a term that describes the process of
stopping the TBM and preparing and executing work under hyperbaric
pressure in the working chamber for the purpose of inspecting,
replacing, or repairing cutting tools and/or the cutterhead structure.
11. Hyperbaric Operations Manual--a detailed, project-specific
health and
[[Page 60760]]
safety plan developed and implemented by the McNally/ASI Marine for
working in compressed air during the Southerly Tunnel and Consolidation
Project.
12. Job hazard analysis--an evaluation of tasks or operations to
identify potential hazards and to determine the necessary controls.
13. Man lock--an enclosed space capable of pressurization, and used
for compressing or decompressing any employee or material when either
is passing into or out of a working chamber.
14. Medical Advisor--medical professional experienced in the
physical requirements of compressed air work and the treatment of
decompression illness.
15. Pressure--a force acting on a unit area; usually expressed as
pounds per square inch (p.s.i.).
16. p.s.i.--pounds per square inch, a common unit of measurement of
pressure; a pressure given in p.s.i. corresponds to absolute pressure.
17. p.s.i.a--pounds per square inch absolute, or absolute pressure,
is the sum of the atmospheric pressure and gauge pressure. At sea
level, atmospheric pressure is approximately 14.7 p.s.i. Adding 14.7 to
a pressure expressed in units of p.s.i.g. will yield the absolute
pressure, expressed as p.s.i.a.
18. p.s.i.g.--pounds per square inch gauge, a common unit of
pressure; pressure expressed as p.s.i.g. corresponds to pressure
relative to atmospheric pressure. At sea level, atmospheric pressure is
approximately 14.7 p.s.i. Subtracting 14.7 from a pressure expressed in
units of p.s.i.a. yields the gauge pressure, expressed as p.s.i.g.
19. Qualified person--an individual who, by possession of a
recognized degree, certificate, or professional standing, or who, by
extensive knowledge, training, and experience, successfully
demonstrates an ability to solve or resolve problems relating to the
subject matter, the work, or the project.\16\
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\16\ Adapted from 29 CFR 1926.32(m).
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20. Working chamber--an enclosed space in the TBM in which CAWs
perform interventions, and which is accessible only through a man-lock.
D. Safety and Health Practices
1. McNally/ASI Marine must implement the project-specific HOM
submitted to OSHA as part of the variance application (see OSHA-2025-
0004-0003). The HOM provides the minimum requirements regarding
expected safety and health hazards (including anticipated geological
conditions) and hyperbaric exposures during the tunnel-construction
project.
2. McNally/ASI Marine must demonstrate that the TBM on the project
is designed, fabricated, inspected, tested, marked and stamped in
accordance with the requirements of the most recent edition of ASME
PVHO-1 (Safety Standards for Pressure Vessels for Human Occupancy) for
the TBM's hyperbaric chambers.
3. McNally/ASI Marine must implement the safety and health
instructions included in the manufacturer's operations manuals for the
TBM, and the safety and health instructions provided by the
manufacturer for the operation of decompression equipment.
4. McNally/ASI Marine must ensure that there are no exposures to
pressures greater than 58 p.s.i.g.
5. McNally/ASI Marine must ensure that air or oxygen is the only
breathing gas in the working chamber.
6. McNally/ASI Marine must follow the 1992 French Decompression
Tables for air or oxygen decompression as specified in the HOM,
specifically the tables titled ``French Regulation Air Standard
Tables.''
7. McNally/ASI Marine must equip man-locks used by their employees
with an oxygen-delivery system as specified by the HOM. McNally/ASI
Marine is prohibited from storing in the tunnel any oxygen or other
compressed gases used in conjunction with hyperbaric work.
8. Workers performing hot work under hyperbaric conditions must use
flame-retardant personal protective equipment and clothing.
9. In hyperbaric work areas, McNally/ASI Marine must maintain an
adequate fire-suppression system approved for hyperbaric work areas.
10. McNally/ASI Marine must develop and implement one or more job
hazard analysis (JHA) for work in the hyperbaric work areas, and
review, periodically and as necessary (e.g., after making changes to a
planned intervention that affects their operation), the contents of the
JHAs with affected employees. The JHAs must include all the job
functions that the risk assessment \17\ indicates are essential to
prevent injury or illness.
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\17\ See ANSI/AIHA Z10-2012, American National Standard for
Occupational Health and Safety Management Systems, for reference.
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11. McNally/ASI Marine must develop a set of checklists to guide
compressed-air work and ensure that employees follow the procedures
required by this permanent variance (including all procedures required
by the HOM, which this permanent variance incorporates by reference).
The checklists must include all steps and equipment functions that the
risk assessment indicates are essential to prevent injury or illness
during compressed-air work.
12. McNally/ASI Marine must ensure that the safety and health
provisions of this project-specific HOM adequately protect the workers
of all contractors and subcontractors involved in hyperbaric operations
for the project to which the HOM applies.\18\
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\18\ See ANSI/ASSE A10.33-2011, American National Standard for
Construction and Demolition Operations--Safety and Health Program
Requirements for Multi-Employer Projects, for reference.
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E. Communication
1. Prior to beginning a shift, McNally/ASI Marine must implement a
system that informs workers exposed to hyperbaric conditions of any
hazardous occurrences or conditions that might affect their safety,
including hyperbaric incidents, gas releases, equipment failures, earth
or rockslides, cave-ins, flooding, fires, or explosions.
2. McNally/ASI Marine must provide a power-assisted means of
communication among affected workers and support personnel in
hyperbaric conditions where unassisted voice communication is
inadequate.
(a) McNally/ASI Marine must use an independent power supply for
powered communication systems, and these systems must operate such that
use or disruption of any one phone or signal location will not disrupt
the operation of the system from any other location.
(b) McNally/ASI Marine must test communication systems at the start
of each shift and as necessary thereafter to ensure proper operation.
F. Worker Qualifications and Training
McNally/ASI Marine must:
1. Ensure that each affected worker receives effective training on
how to safely enter, work in, exit from, and undertake emergency
evacuation or rescue from, hyperbaric conditions, and document this
training.
2. Provide effective instruction, before beginning hyperbaric
operations, to each worker who performs work, or controls the exposure
of others, in hyperbaric conditions, and document this instruction. The
instruction must include:
(a) The physics and physiology of hyperbaric work;
(b) Recognition of pressure-related injuries;
[[Page 60761]]
(c) Information on the causes and recognition of the signs and
symptoms associated with decompression illness, and other hyperbaric
intervention-related health effects (e.g., barotrauma, nitrogen
narcosis, and oxygen toxicity);
(d) How to avoid discomfort during compression and decompression;
(e) Information the workers can use to contact the appropriate
healthcare professionals should the workers have concerns that they may
be experiencing adverse health effects from hyperbaric exposure; and
(f) Procedures and requirements applicable to the employee in the
project-specific HOM.
3. Repeat the instruction specified in paragraph (2) of this
condition periodically and as necessary (e.g., after making changes to
their hyperbaric operations).
4. When conducting training for their hyperbaric workers, make this
training available to OSHA personnel and notify OTPCA at OSHA's
national office and the Cleveland, Ohio OSHA Area Office before the
training takes place.
G. Inspections, Tests, and Accident Prevention
1. McNally/ASI Marine must initiate and maintain a program of
frequent and regular inspections of the TBM's hyperbaric equipment and
support systems (such as temperature control, illumination,
ventilation, and fire-prevention and fire-suppression systems), and
hyperbaric work areas, as required under 29 CFR 1926.20(b)(2),
including:
(a) Developing a set of checklists to be used by a competent person
in conducting weekly inspections of hyperbaric equipment and work
areas; and
(b) Ensuring that a competent person conducts daily visual checks,
as well as weekly inspections of the TBM.
2. McNally/ASI Marine must remove from service any equipment that
constitutes a safety hazard until it corrects the hazardous condition
and has the correction approved by a qualified person.
3. McNally/ASI Marine must maintain records of all tests and
inspections of the TBM, as well as associated corrective actions and
repairs, at the job site for the duration of the tunneling project and
for 90 days after the final project report is submitted to OSHA.
H. Compression and Decompression
McNally/ASI Marine must consult with their attending physician
concerning the need for special compression or decompression exposures
appropriate for CAWs not acclimated to hyperbaric exposure.
I. Recordkeeping
In addition to completing OSHA Form 301 Injury and Illness Incident
Report and OSHA Form 300 Log of Work-Related Injuries and Illnesses,
McNally/ASI Marine must maintain records of:
1. The date, times (e.g., time compression started, time spent
compressing, time performing intervention, time spent decompressing),
and pressure for each hyperbaric intervention.
2. The names of all supervisors and DMTs involved for each
intervention.
3. The name of each individual worker exposed to hyperbaric
pressure and the decompression protocols and results for each worker.
4. The total number of interventions and the amount of hyperbaric
work time at each pressure.
5. The results of the post-intervention physical assessment of each
CAW for signs and symptoms of decompression illness, barotrauma,
nitrogen narcosis, oxygen toxicity or other health effects associated
with work in compressed air for each hyperbaric intervention.
J. Notifications
1. To assist OSHA in administering the conditions specified herein,
McNally/ASI Marine must:
(a) Notify the OTPCA and the Cleveland Ohio OSHA Area Office of any
recordable injury, illness, or fatality (by submitting the completed
OSHA's Form 301 Injury and Illness Incident Report form) \19\ resulting
from exposure of an employee to hyperbaric conditions, including those
exposures that do not require recompression treatment (e.g., nitrogen
narcosis, oxygen toxicity, barotrauma), but still meet the recordable
injury or illness criteria of 29 CFR 1904. The notification must be
made within 8 hours of the incident or 8 hours after becoming aware of
a recordable injury, illness, or fatality, and submit a copy of the
incident investigation (OSHA's Form 301 Injury and Illness Injury
Reporting Form) within 24 hours of the incident or 24 hours after
becoming aware of a recordable injury, illness, or fatality. In
addition to the information required by the OSHA's Form 301 Injury and
Illness Injury Reporting Form, the incident-investigation report must
include a root-cause determination, and the preventive and corrective
actions identified and implemented.
---------------------------------------------------------------------------
\19\ See 29 CFR 1904 (Recording and Reporting Occupational
Injuries and Illnesses) (<a href="http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=9631">http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=9631</a>); recordkeeping
forms and instructions <a href="https://www.osha.gov/recordkeeping/forms">https://www.osha.gov/recordkeeping/forms</a>.
---------------------------------------------------------------------------
(b) Provide certification within 15 days of the incident that the
employer informed affected workers of the incident and the results of
the incident investigation (including the root-cause determination and
preventive and corrective actions identified and implemented).
(c) Notify the OTPCA and the Cleveland Ohio OSHA Area Office within
15 working days in writing of any change in the compressed-air
operations that affects the employer's ability to comply with the
conditions specified herein.
(d) Upon completion of the Southerly Tunnel and Consolidation
Project, evaluate the effectiveness of the decompression tables used
throughout the project, and provide a written report of this evaluation
to the OTPCA and the Cleveland Ohio OSHA Area Office.
Note: The evaluation report is to contain summaries of: (1) the
number, dates, durations, and pressures of the hyperbaric
interventions completed; (2) decompression protocols implemented
(including composition of gas mixtures (air and/or oxygen), and the
results achieved; (3) the total number of interventions and the
number of hyperbaric incidents (decompression illnesses and/or
health effects associated with hyperbaric interventions as recorded
on OSHA's Form 301 Injury and Illness Incident Report and OSHA's
Form 300 Log of Work-Related Injuries and Illnesses, and relevant
medical diagnoses and treating physicians' opinions); and (4) root
causes of any hyperbaric incidents, and preventive and corrective
actions identified and implemented.
(e) To assist OSHA in administering the conditions specified
herein, inform the OTPCA and the Cleveland Ohio OSHA Area Office as
soon as possible, but no later than seven (7) days, after it has
knowledge that it will:
i. Cease to do business;
ii. Change the location and address of the main office for managing
the
tunneling operations specified herein; or
iii. Transfer the operations specified herein to a successor
company.
(f) Notify all affected employees of this permanent variance by the
same means required to inform them of the application for a variance.
(g) This permanent variance cannot be transferred to a successor
company without OSHA approval.
OSHA hereby grants a permanent variance to McNally/ASI Marine to
the provisions of 29 CFR 1926.803 outlined in this notice for the
completion of the Southerly Tunnel and Consolidation Project in
Cleveland, Ohio.
[[Page 60762]]
VIII. Authority and Signature
David Keeling, Assistant Secretary of Labor for Occupational Safety
and Health, 200 Constitution Avenue NW, Washington, DC 20210,
authorized the preparation of this notice. Accordingly, the agency is
issuing this notice pursuant to 29 U.S.C. 655(d), Secretary of Labor's
Order No. 7-2025 (90 FR 27878, June 30, 2025), and 29 CFR 1905.11.
Signed at Washington, DC, on December 19, 2025.
David Keeling,
Assistant Secretary of Labor for Occupational Safety and Health.
[FR Doc. 2025-23804 Filed 12-23-25; 8:45 am]
BILLING CODE 4510-26-P
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</html>Indexed from Federal Register on December 29, 2025.
This is legal information, not legal advice. Laws vary by jurisdiction and change frequently. Always verify current law with official sources and consult a licensed attorney in your jurisdiction for advice on your specific situation.