By Louie St. George III
As demolition winds down on Essentia Health’s $800 million Vision Northland construction project, the next phase got underway this afternoon. Crews began blasting to excavate more than 44,000 cubic yards of rock from the site.
Blasting is set to occur at noon and 4 p.m. every weekday through April. Today marked a test run, and it unfolded as expected, said officials from Essentia, construction manager McGough Construction and excavation contractor Northland Constructors.
“The test blast followed all safety measures and protocols and went according to plan,” said Phil Johnson, project manager for McGough. “It met all compliance specifications according to data from our engineers.”
The amount of basalt being hauled away will fill some 5,500 dump trucks. It’s enough to erect a 70-foot-high pile over the entire sheet of ice at Amsoil Arena. Blasting will occur along Fourth Avenue East, starting on Superior Street and moving up the hill to Second Street. And while the word “blasting” evokes images of explosions, this work will sound like a muffled thud rather than a bang (see attached video).
There is the potential for each blast to be felt within about a 300-foot radius. Excavation closest to buildings will be done via mechanical tools to minimize vibrations. No impact to patient care is expected on Essentia Health’s downtown medical campus.
Each excavation area is covered with mats and tires to prevent flying rock. Similarly, safety officers and vibration sensors are placed throughout the area to ensure that strict protocols — established by federal and state agencies — are adhered to. We’re also working closely with the Minnesota Department of Transportation because blasting will occur close to Interstate 35 tunnels.
There is a strict schedule that will be followed leading up to blasts at noon and 4 p.m. each weekday. Air horn signals will sound both five minutes and one minute before blast. Communication will be ongoing between the contractor and Essentia Health, and blasting can halt if necessary.
Between 330-350 cubic yards of rock will be removed daily as the future site of Essentia’s state-of-the-art replacement hospital is prepped for foundations, which are slated to be completed in the spring of 2020.
“Moving into this next phase marks another important milestone for a project that will allow us to deliver the highest caliber of health care to our patients,” said Dr. Robert Erickson, Essentia’s physician leader for Vision Northland. “We are thrilled to be progressing from demolition to preparing the site for construction.”
The rock will be hauled to a location on Garfield Avenue. From there, uses could include as a breakwater along Duluth’s Lakewalk and the shoreline of Lake Superior in Bayfield County, though nothing has been finalized.
Crews are using data gleaned from engineering studies and blasting done during construction of the Duluth Clinic’s First Street Building on the Essentia Health downtown medical campus, from 2004-06, as well as construction of I-35. Because of the city’s topography, this level of rock excavation is not uncommon in Duluth.