Nearly a year after the collapse of an under-construction pre-engineered steel airplane hangar in Boise, Idaho, killed three workers, construction has resumed with the original contractor, Big D Builders Inc.

The Meridian, Idaho-based contractor—which is not affiliated with Salt Lake City-based Big-D Construction Corp.—is constructing the 39,000-sq-ft, 45.5-ft-tall hangar for Jackson Jet Center, a private plane charter and maintenance company. The original structure collapsed last Jan. 31, killing workers Mariano Coc Och, 32, and Mario Sontay Tzi, 24, as well as Big-D Construction co-founder Craig Durrant, 59, and seriously injuring eight others.

In June, city officials issued a permit for removal of steel and concrete that had been installed but was damaged in the collapse. The hangar was to be rebuilt using the existing building permit, with modifications to be made to structural drawings, records show. 

The contractor filed a plan modification with the city Jan. 21, 2025. According to the application, base plate drawings for the 14 main columns were modified from the approved drawings, which had a 4-in. spread pattern on the bolts, to instead have a 5-in. spread pattern, which required removal of the factory-welded baseplates so they could be replaced with the correct bolt spacing. An added X-brace flange also necessitated two additional bolts. 

Big D and other firms involved with the project are currently facing a lawsuit brought by the families of Sontay Tzi and Coc Och. In the suit, the families allege the plans had been modified without approval from city officials prior to the collapse. 

It was not immediately clear whether the newly filed plan modifications are similar to any others that may have been made before the collapse. In a response to the lawsuit, the contractor denied most of the allegations. A representative for Big D confirmed work had resumed but otherwise declined to comment on the project. 

The contractor is also facing penalties totaling nearly $200,000 from the U.S. Dept. of Labor’s Occupational Safety and Health Administration for one willful and three serious violations inspectors issued after the collapse. OSHA officials said the contractor ignored signs the structure was unstable and used “irresponsible construction methods.” Big D has contested the citations, records show. 

OSHA also cited Boise-based Inland Crane Inc. in connection to the collapse. That firm has also contested its citation.