McNally Tunneling Corp./ASI Marine Southerly Tunnel and Consolidation Project: Grant of Permanent Variance

<NOTICE> DEPARTMENT OF LABOR <SUBAGY>Occupational Safety and Health Administration</SUBAGY> <DEPDOC>[Docket No. OSHA-2025-0004]</DEPDOC> <SUBJECT>McNally Tunneling Corp./ASI Marine Southerly Tunnel and Consolidation Project: Grant of Permanent Variance</SUBJECT> <HD SOURCE="HED">AGENCY:</HD> Occupational Safety and Health Administration (OSHA), Labor. <HD SOURCE="HED">ACTION:</HD> Notice. <SUM> <HD SOURCE="HED">SUMMARY:</HD> In this notice, OSHA grants a permanent variance to McNally Tunneling Corp./ASI Marine (McNally/ASI Marine) related to work in compressed-air environments. </SUM> <DATES> <HD SOURCE="HED">DATES:</HD> 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. </DATES> <FURINF> <HD SOURCE="HED">FOR FURTHER INFORMATION CONTACT:</HD> Information regarding this notice is available from the following sources: <E T="03">Press inquiries:</E> Contact Mr. Frank Meilinger, Director, OSHA Office of Communications, phone: (202) 693-1999; email: <E T="03">meilinger.francis2@dol.gov.</E> <E T="03">General and Technical Information:</E> 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: <E T="03">robinson.kevin@dol.gov.</E> </FURINF> <SUPLINF> <HD SOURCE="HED">SUPPLEMENTARY INFORMATION:</HD> <E T="03">Copies of this</E> <E T="04">Federal Register</E> <E T="03"> notice:</E> Electronic copies of this <E T="04">Federal Register</E> notice are available at <E T="03">http://www.regulations.gov.</E> This <E T="04">Federal Register</E> notice and other relevant information are also available at OSHA's web page at <E T="03">http://www.osha.gov.</E> <HD SOURCE="HD1">I. Overview</HD> 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));  <SU>1</SU> <FTREF/> (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). <FTNT> <SU>1</SU>  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. </FTNT> 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 <E T="04">Federal Register</E> 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. <HD SOURCE="HD2">A. Background</HD> 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 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 i ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Preview showing 10k of 75k characters. Full document text is stored and available for version comparison. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━