NYS Route 32 Bridge Piers (Cohoes-Waterford Bridge)
THE PROJECT
After NYDOT’s award of the demolition contract for the NYS Route 32 Bridge between Cohoes and Waterford, New York, DA Collins finalized a relationship started during the bid period with CDI to design and perform the fragmentation of the six (6) reinforced concrete piers after the deck and concrete arches above were pre-removed. The project was complicated, not only by the new bridge which was situated just 17’ from the end of the piers to be blasted, but by historic structures that were less than 50’ from the pier to be blasted at the end of the structure.
Once the arches were removed by DA Collins, and relief had been excavated around each pier to the limit of removal, CDI crews drilled 3” and 3 ½” diameter holes vertically in the piers to distribute explosives energy in a fashion that would ensure well-fragmented debris while minimizing the lbs. of explosives being detonated per delay, to control vibration from blasting operations.
CDI loaded a total of 3,250 lbs. of propagation-resistant dynamite into concert with a non-electric initiation system designed to mitigate vibration from blasting operations.
Pre-blast surveys were conducted by CDI, using an independent third-party geotechnical firm, and eight (8), 3-compoent seismographs were positioned on each of the adjacent new bridge piers and on private property at either end of the blasting zone.
THE DETONATION
Traffic on the adjacent bridge was stopped five (5) minutes before the shot which was detonated on October 5, 2017, without fly of debris, or vibration impacting the new bridge or third-party improvements to remain. Post-blast surveys made, following the blast, indicated that there had been no change to the pre-blast condition of the new bridge or adjacent properties inspected.
Click HERE to watch the blasting of the Cohoes-Waterford Bridge Piers.
