LINCOLN SQUARE — Neighbors who live along the footprint of the Albany Park Storm Water Diversion Tunnel are bracing for boring explosions set to start near the end of October, but project engineers said the daily stream of truck traffic hauling away debris is likely to cause more headaches.
The "blasting spoils" will be carted away by as many as 100 truck trips a day, according to Vasile Jurca, a civil engineer with the Chicago Department of Transportation.
The truck trips will be split between the tunnel's inlet and outlet shaft construction sites: the former is near Foster and Springfield avenues, the latter is at Foster Avenue and the Chicago River in River Park.
Approximately every five minutes, a truck will be entering Foster Avenue, on its way to the Edens Expressway, Jurca informed residents during a community meeting held Tuesday night at Swedish Covenant Hospital.
"What we have to do is remove rock after the blast. It is a pain, I understand," he said. "It's construction, so bear with us."
Foster Avenue has been closed between Pulaski and Cicero — directly in the trucks' path — since early September for bridge repair work being conducted by the Illinois Department of Transportation.
The road is expected to reopen in mid-October, prior to the beginning of blasting, according to Frank "Sonny" Jaramilla, the tunnel's on-site project manager for the engineering firm Parsons Brinckerhoff.
"Trucks will be avoiding rush hour, if that's any silver lining," Jaramilla said.
The majority of the sparsely attended meeting, however, was devoted to prepping neighbors for the pending daily blasts needed to create the tunnel's shafts, which will drop 150 feet underground, the last 80 feet of which will cut through stubborn limestone.
Homeowners who live within 500 feet of the inlet and outlet shafts have already been contacted regarding voluntary property inspections, intended to document conditions prior to the start of blasting and determine whether vibrations from the controlled explosions cause any damage.
Residents within 200 feet on either side of the tunnel's footprint under Foster Avenue are similarly being contacted this week.
Answers to commonly asked questions:
How long will the blasting take place?
Blasting and excavation at the outlet shaft is expected to occur from late October through January 2017, with the first blast taking place as soon as Oct. 24.
The same work at the inlet shaft is expected to last from December through February 2017.
How often will there be blasts and when will they occur?
There will only be one blast per day, lasting for a few seconds. Blasts are permitted between 8 a.m and 6 p.m., but the target timing is between 10 a.m. and 1 p.m., according to Jaramilla.
Pedestrian and auto traffic will be stopped briefly to the east and west of the blast site, but emergency vehicles will not be obstructed, which is of particular concern given the location of Swedish Covenant Hospital at Foster and California avenues.
How will people know a blast is coming?
A series of warning horn signals will alert people in the area that a blast is about to occur.
The series is: a 10-second signal five minutes before a blast, two five-second signals one minute before a blast, three two-second signals 10 seconds before a blast, and four two-second signals to indicate an "all clear."
How loud are the blasts?
The decibel levels are quieter than a jet airplane but slightly louder than a motorcycle, Jaramilla said.
Blast mats and shaft covers will be used to minimize noise and vibrations, he said.
How safe is the blasting process and could it damage utility lines?
Seismographs have been placed at strategic locations around the shaft sites to monitor vibration levels near gas lines and other points of concern, including equipment at Swedish Covenant such as MRI machines, according to Michael Spors, of Vibra-tech, which is consulting on the tunnel project.
Construction crews will conduct a test blast to measure the vibration's effect and adjust accordingly, Jaramilla said.
Blasting is "something that's done regularly" and has been "studied very rigorously," Spors said.
Limits in place for the tunnel project are extremely conservative and "far below any damage ever noted," he said.
"On July 4th in this area we get more blasting in 12 hours than you'll get during this entire process," said Ald. Pat O'Connor (40th).
Nevertheless O'Connor said he had assigned a staff member in his office to handle any complaints related to the blasting.
"Don't sit on the problem and come back weeks later or months later," he urged residents.
Once the shafts have been excavated, a tunnel boring machine will be brought on site in January 2017 and assembled underground, itself a major feat, according to Jurca.
"It comes in a thousand pieces," he said.
The borer will chew its way north from the outlet shaft to the inlet, from February through May 2017.
The shafts and tunnel will be lined with concrete, with a minimum lifespan of 50 years, Jurca said.
The entire project will wrap up in spring 2018, including landscaping and restoration of the areas around the inlet and outlet shafts.
The footprint of the entire tunnel project, depicting homes within the blast boundaries.
The inlet shaft site.
The outlet shaft site in River Park.
Once the shafts have been excavated, a tunnel boring machine will be brought on site in January 2017 and assembled underground.
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