Florida Construction News staff writer
The federal team investigating the collapse of the Champlain Towers South condominium in Surfside has moved evidence to a new warehouse and started the next phase of the investigation, the National Institute of Standards and Technology (NIST) has announced.
An update on work related to the investigation will be presented at the NCST advisory committee meeting on June 14 and 15, which is open to the public. Registration details can be found in the Federal Register notice for the meeting.
Miami-Dade police and NIST staff finished overseeing the transfer of 300 pieces of physical evidence originally retrieved from the Surfside site to a second warehouse, both located in Miami-Dade County, earlier this month, almost two years after a portion of the 12-story building collapsed, killing 99 people, in the early morning hours of June 24, 2021.
The new space is needed to safely access the specimens and begin the next phase of evidence analysis, which will include extracting samples of concrete and reinforcing steel from the specimens retrieved from the Surfside, Florida, collapse site. The challenging move of more than 300 building specimens was managed by MDPD contractors and subcontractors and overseen by NIST staff.
“The first warehouse was not large enough to allow our staff members and others to safely conduct all of the analysis that needs to be done to help us understand the condition of the building materials at the time of the collapse,” said Judith Mitrani-Reiser, co-lead of the investigation. “This second, larger warehouse will allow us to create sufficient space around each specimen so that we can bring in equipment to safely manipulate, cut and core specimens to extract samples.”
Moving evidence required “careful coordination and execution” to ensure no specimens were damaged. The NCST team followed a strict chain of custody process with extensive documentation at each step.
“In order to preserve the chain of custody, we had team members at the original warehouse checking what was loaded onto the truck, and at the second warehouse verifying that what was loaded onto the truck at the previous facility arrived at the new facility in the same condition as when it was loaded,” said Chris Segura, co-lead of the investigation’s evidence preservation project. “At times, we also had staff accompanying the transport itself.”
The investigation has focused on structural modeling, interviews of eyewitnesses and others familiar with the building, reviews of historical documents, and non-destructive testing using methods such as visual inspection and measuring how sound moves through the evidence specimens to assess a range of material properties without cutting into or physically altering the specimens.
Non-destructive testing helps the team better understand the building’s as-built condition and develop the testing plan for extracting samples through what is called invasive testing. The first phase of invasive testing has begun, led by engineering and materials science experts from the NCST and the U.S. Army Corps of Engineers.
“Concrete cores and steel reinforcing bar samples will be tested to determine their strength and deformation properties,” said Glenn Bell, co-lead of the investigation. “These properties will be used in our computer simulation models of the building failure and will also inform the composition of the concrete we mix to construct laboratory mock-ups of building components to use as test specimens. Concrete samples will also be subjected to microscopy, chemical analysis and other materials testing to evaluate sample integrity and durability, and to check for deterioration and aging mechanisms.”
The investigation is one of the most complex and challenging of its type ever undertaken, with no obvious initiating event for the collapse. NIST anticipates that the technical aspects of the investigation will be completed by the spring 2024 and a report with recommendations will be issued a year later.
