Explosives
experts with Demtech Inc., Dubois, Wyoming USA have safely
felled a damaged 80-foot section of the new Memorial Causeway
Bridge in Clearwater, Florida.
The bridge, which is part of a $70 million (US) reconstruction
project, suffered a partial collapse when steel crossbeams
rolled as workers were repositioning concrete forms in December
2002. Construction managers for the prime contractor, PCL
Constructors, decided to completely demolish the damaged span
with explosives rather than put workers at risk with manual
deconstruction.
Officials
then contracted Demtech to perform the actual demolition due
to their reputation as one of the country's most successful
emergency blasting teams. (The same firm successfully felled
the heavily damaged I-40 Bridge in Weber Falls, Oklahoma a
few months earlier after a barge rammed the structure, causing
multiple fatalities).
Upon arriving on site, Demtech President Scott Gustafson and
his crew worked 24 consecutive hours to ensure minimal disruption
to the heavily traveled Route 60 Highway located less than
100 feet from the blast zone. The team pre-weakened multiple
supports and braces to ensure a proper direction of fall,
then attached fourteen pounds of custom fabricated semi-circular
RDX charges to eight 20-inch diameter cylindrical steel support
piles at sixteen severance points.
While this was occurring, a team from Protec Documentation
Services, Mt. Laurel, New Jersey meticulously inspected all
adjacent bridge piers and nearby businesses for any pre-existing
structural defects. The team also developed impact calculations
and researched its database of similar projects to help ensure
the demolition would not harm adjacent properties or cause
further damage to the bridge.
At
precisely three o'clock in the morning, traffic on Route 60
was stopped, Clearwater Harbour was closed to recreational
boating and aerial observers radioed that no manatees (an
endangered marine mammal) were in the vicinity. Demtech's
Steve Rainwater then initiated the blast, and 1-million pounds
of concrete dropped 45 feet onto the side of a protective
dirt berm as anticipated.
A short time after the dust cleared, Protec confirmed that
no damage occurred to the remainder of the bridge or surrounding
properties, and City Public Services Director Gary Johnson
observed, "The project couldn't have gone any better."
