2018 Update #23
Test Blast Considered a Success; Second Blast Possible Thursday Afternoon
Eight weeks in we’re becoming accustomed to the sights and sounds of construction in our central downtown.
On Wednesday there were quite a few more reflective vests on hand, here to conduct and evaluate a test blast in Printer’s Alley, the first of several needed to excavate the bare bones of a new drainage system out of the bedrock running perpendicular to Main Street.
This was an important next step, and it was clear not only that a lot of experienced eyes were on this blasting plan but also that blasting in such close proximity to the National Bank, among other downtown buildings, meant taking a highly conservative approach both to the size of the blast and to protecting the public.
By all accounts the test blast was a success.
First and foremost, the blast took place safely. No one who shouldn’t have got anywhere near the blast. The 200,000 pounds of blasting mats that were meticulously laid over the blast site did their job, allowing only a brief puff of dust to emerge into the air.
From what I observed, everyone who was asked to wait outside the blasting zone, whether on foot, bike or car, seemed to wait patiently during the two minutes that elapsed between “shut down” and “all clear.” I think some who came to witness “the blast” walked away a little disappointed. “That was it?”
Going door to door on Main Street and Merchants Row afterwards, I learned that most heard the noise of the blast and those in the Main Street stores closest to the National Bank felt it. But no pictures rattled and no displays fell to the floor. Sigh of relief there.
From a technical perspective, the blast team wanted to evaluate 1) the state of the rock once fractured by the blast and 2) the ground vibrations generated by the blast as monitored in adjoining buildings and reported out in real time. Everything there checked out according to plan.
In larger terms, this was a project team exercise in managing public safety during the blasting process and in building a good line of communication with our community downtown.
Finally, I would be remiss, especially on what was an unusually warm Wednesday in May, if I didn't thank the remarkable team at the National Bank of Middlebury for marking the event with post-blast ice cream sandwiches for the entire construction crew. That brought a smile to everyone's face after the morning's intense preparations.
What’s Next
Following a late Wednesday afternoon project team meeting, Maine D&B was cleared to drill more holes on Thursday morning and, if that work can be completed in time, to stage a second blast mid-Thursday afternoon.
This would be similar in magnitude to Wednesday’s blast and would continue the job of excavating the top layer of bedrock in Printer’s Alley.
Let’s assume that will take place and I will confirm as early as I can tomorrow with those in nearby buildings and businesses.
Again, the Whistles
If you were in a building downtown yesterday at blast time it could be hard to hear the whistle alert that signals a blast event. Next blast we’ll supplement the whistles with a verbal heads-up alert to those in nearby buildings at 20 minutes out.
As a reminder, here’s the whistle warning sequence that will be sounded prior to commencement of the blast to alert those in the area that a blast is imminent.
4 whistles = we’re 20 minutes out from the blast
3 whistles = 5 minutes to go
2 whistles = 1 minute to go
1 whistle = All clear
That’s all for today. See you downtown.
Please keep your comments and questions coming. Send me an email at jgish@townofmiddlebury.org and I’ll try to cover it in my next update.