Department of Labor Logo OSHA National News Release

January 26, 2023

Facing manslaughter charges in worker's 2021 trench collapse death, Colorado contractor who willfully ignored federal law surrenders to police

A4S LLC did not use legally required trench protection systems

BRECKENRIDGE, CO – The owner of a Vail construction company facing felony manslaughter charges has surrendered to local law enforcement after the Summit County Sheriff's Office in Breckenridge, Colorado, issued an arrest warrant on Jan. 24, 2023, related to the findings of a federal safety investigation into a deadly trench collapse in November 2021.

In May 2022, the U.S. Department of Labor's Occupational Safety and Health Administration cited Peter Dillon, owner of the now-defunct A4S LLC, after a worker installing residential sewer pipes suffered fatal injuries when the trench around him caved in. The collapse resulted from deteriorating conditions at the project, which A4S LLC could have prevented by using legally required trench protection systems.

OSHA issued three willful citations to A4S LLC for not ensuring the excavation was inspected by a competent person, failing to instruct employees on the recognition and avoidance of unsafe conditions and not having a trench protective system in place. Investigators also issued an additional serious citation for not having a safe means of egress within 25 lateral feet of employees working in a trench.

The agency proposed penalties of $449,583 and placed the company in OSHA’s Severe Violator Enforcement Program.

The department referred the case to the 5th Judicial District Attorney's office recommending criminal charges for A4S LLC's refusal to require safety protection, despite worsening trench conditions that included at least one trench collapse.

A4S LLC has since shuttered and Dillon agreed to forfeit any future ownership, leadership or management position that involves trenching or excavation, or the oversight of workplace safety and health.  

"There is no excuse for Peter Dillon’s failures to protect workers when federal requirements clearly outline and require safety measures proven to save lives," explained Regional Solicitor of Labor John Rainwater in Dallas. "Today's arrest by the Summit County Sheriff's Office cannot recover a life lost in this senseless tragedy but it is a step toward seeking justice for the family."

Collapses and cave-ins pose the greatest threat to trenching and excavation workers. In 2022, OSHA reported that at least 39 industry workers died, 22 of them in the first six months of the year. The Bureau of Labor Statistics reports that 166 workers died in trench collapses from 2011 to 2018.

"Let this tragedy serve as a reminder to other employers who willingly fail in their responsibilities to keep workers safe that the U.S. Department of Labor will exhaust every resource to hold employers accountable for protecting workers, including recommending criminal prosecution. OSHA has pledged to work with state prosecutors to raise the stakes in appropriate trenching death cases, and this is an example," added OSHA Regional Administrator Jennifer S. Rous in Denver.

OSHA has a National Emphasis Program on trenching and excavations. Trenching standards require protective systems on trenches deeper than 5 feet. Additionally, trenches must be inspected by a knowledgeable person and have a safe means of entering and exiting prior to allowing a worker to enter.

Learn more about OSHA.

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Media Contacts:

Chauntra Rideaux, 972-850-4710,
Juan J. Rodríguez, 972-850-4709,

Release Number: 23-75-NAT