# 2025-23805: OSHA Grants Variance for Potomac River Tunnel's Compressed Air Operations

2025-23805, CBNA/Halmar Joint Venture; Potomac River Tunnel Project; Grant of Permanent Variance, is a Federal Register notice from Labor Department, Occupational Safety and Health Administration published 2025-12-29, effective 2025-12-29 (as of 2026-06-08).

- Canonical: https://policyrisk.com/federal-register/2025-23805
- As of: 2026-06-08
- Plain-text twin of the page above; the HTML and this file carry the same facts.

## Facts
- Document number: 2025-23805
- Title: CBNA/Halmar Joint Venture; Potomac River Tunnel Project; Grant of Permanent Variance
- Type: Notice
- Agencies: Labor Department; Occupational Safety and Health Administration
- Citation: 90 FR 60742
- Published: 2025-12-29
- Effective: 2025-12-29
- Comments close: not stated
- Significant: no
- Touches household money: no
- Regulation identifier numbers: none
- Last updated: 2026-06-08

## In one line

OSHA Grants Variance for Potomac River Tunnel's Compressed Air Operations

## Summary

OSHA has given CBNA/Halmar Joint Venture a permanent green light to work in special compressed air conditions for the Potomac River Tunnel Project in Washington, DC. This change lets them follow different safety rules until the project wraps up, starting December 29, 2025. Workers on this tunnel project are affected, and the variance helps keep the work moving smoothly without extra delays or costs.

## Abstract

In this notice, OSHA grants a permanent variance to CBNA/ Halmar Joint Venture (CBNA/Halmar) related to work in compressed air environments.

## Effects PRIA read

- Permanent variance for Potomac Tunnel: benefit, medium. OSHA granted CBNA/Halmar a permanent variance that takes effect on December 29, 2025 and stays in place until the Potomac River Tunnel Project is finished or OSHA modifies or revokes it. The variance applies only to CBNA/Halmar and only to construction work on the Potomac River Tunnel Project and a…
- Use of 1992 French decompression tables: benefit, medium. CBNA/Halmar may use the 1992 French Decompression Tables (including staged decompression with air and/or pure oxygen) instead of OSHA's decompression tables for compressed-air workers. OSHA's notice states oxygen-assisted decompression can reduce decompression time by about 33 percent and that a ph…
- Manual staged decompression under supervision: benefit, low. Instead of automatic continuous decompression controllers, CBNA/Halmar will use staged decompression carried out under a trained man-lock attendant and overseen by a hyperbaric supervisor and an attending physician certified in hyperbaric medicine. OSHA determined this manual, staged approach is at…
- Man-locks replace special decompression chamber: benefit, low. Because space in the tunnel-boring machine (TBM) is limited, CBNA/Halmar may use the TBM’s twin man-locks and staging chamber in place of a separate special decompression chamber. The permanent variance limits the maximum crew in the working chamber to three people and the TBM arrangement is descri…
- Stronger safety paperwork and prompt reporting: benefit, low. CBNA/Halmar must submit a project-specific Hyperbaric Operations Manual (HOM) and proof of compliance with ASME PVHO-1 at least six months before using the TBM, keep detailed records of hyperbaric interventions (including completing OSHA Form 301), notify OSHA within 24 hours of hyperbaric recordab…

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## Sources
- [2025-23805 on federalregister.gov](https://www.federalregister.gov/documents/2025/12/29/2025-23805/cbnahalmar-joint-venture-potomac-river-tunnel-project-grant-of-permanent-variance)
- [2025-23805 as published (PDF)](https://www.govinfo.gov/content/pkg/FR-2025-12-29/pdf/2025-23805.pdf)

## Related
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- [Next: 2025-23806, Notice of Receipt of Complaint; Solicitation of Comments Relating to the Public…](https://policyrisk.com/federal-register/2025-23806)
- [All Federal Register documents](https://policyrisk.com/federal-register)

Source: PRIA, https://policyrisk.com/federal-register/2025-23805 (as of 2026-06-08).