River Park Bike Path Barriers View Full Caption

LINCOLN SQUARE — They might look like super-sized Legos, but the barriers recently installed along River Park's bike path aren't intended for child's play.

The bright orange blocks mark a detour around what's about to become the epicenter of drilling for the Albany Park storm water diversion tunnel.

The path's underpass at Foster Avenue has been fenced off in both directions, with pedestrians, joggers and cyclists rerouted to a new signal crossing at Foster, west of Francisco.

The portion of the park surrounding the south side of the underpass is being prepped for the excavation of a 150-foot-deep shaft.

Neighbors can expect a detonation approximately every other day — weekdays and daytime hours only, one explosion per occurrence — as crews create the shaft.

The blasts will sound like fireworks and cause noticeable vibrations, according to engineers with the Chicago Department of Transportation.

Community meetings will be held before blasting gets underway within the next couple months, according to a department spokeswoman.

Properties within 500 feet of the explosions will be surveyed and monitored for damage from the rattling.

Once the shaft is built, along with its twin at the tunnel's western inlet, construction will largely move underground. A tunnel boring machine will be lowered down the River Park shaft and chew its way under Foster, grinding a hole 18 feet in diameter and a mile long.

The section of River Park — normally home to a baseball and soccer field, in addition to the bike path underpass — will be closed off for two years. At the conclusion of the tunnel project, the area will be restored with a new soccer field and regulation-sized baseball field.

A permanent control center will be built at the outlet shaft, with a design expected to mimic River Park's fieldhouse.

The $70 million tunnel will divert storm water from the North Branch of the Chicago River to an outlet about a mile to the east, where it will dump back out into the North Shore Channel.

Plans were drawn up for the tunnel after a string of "100-year" storms saw the river top its flood level of 7 feet in 2008, 2010 and 2013.

In April 2013, the river crested at 8.85 feet, causing massive flooding that forced some folks to be evacuated from their homes by boat in Albany Park and North Park.

Heavy rains in July of this year saw the river swell above 6 feet (5 feet is considered "action" level).

During the recent storm, concrete "jersey" barriers were put in place near the most vulnerable homes as a stop-gap flood-prevention measure.

The bright orange blocks mark a detour around what's about to become the epicenter of drilling for the Albany Park storm water diversion tunnel. [All photos DNAinfo/Patty Wetli]

The bike path's underpass at Foster Avenue has been fenced off in both directions.

Pedestrians, joggers and cyclists have been rerouted to a new signal crossing at Foster, west of Francisco.

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