The retaining walls for the Library
Lot underground parking garage are going higher as construction
workers continue to dig deeper into downtown Ann Arbor.
Work crews
have dug most of the panhandle section of the project that reaches out
to Division Street and are gearing up to take on the large section that
fronts Fifth Avenue. The plan is to drill
in the last retaining wall pylons this spring, while expanding the dig this summer. The Fifth Avenue
section will be scraped out in August. The entire hole should be dug by September, which is more challenging than it appears.
"Logistics is actually the hard part of this
project," says Gary Shannon, senior project superintendent for Christman, which is
quarterbacking construction for the project.
That hard part
equals out to 250,000 cubic yards of mostly clean dirt (the soil is
virgin after you get below the initial 8-10 feet) that needs to be
excavated, followed by the removal of excavation equipment. Some of
the dirt will be reused for the concrete for the 677-car parking deck. The
rest will be shipped to an off-site just outside of the city and be used
by other construction projects in southeast Michigan.
Once the
dirt is removed, concrete will begin - all 43,000 cubic yards of
it. To put that in perspective, that's enough cement to pour a new
sidewalk between Ann Arbor and Battle Creek, on both sides of the
street. This will be accompanied by 4,500 tons of reinforcing steel that will be
embedded into the structure. (Another fun fact: Laid out end to end, the steel would
run almost 650 miles).
The whole project,
which will stretch well into next year, is employing about 35-40 people
right now. It will hit its maximum crew size of 130-140 people when the
concrete pour is in full swing.
Source: Gary Shannon, senior
project superintendent for Christman and Adrian Iraola, president of
Park Avenue Consultants
Writer: Jon Zemke
Enjoy this story?
Sign up for free solutions-based reporting in your inbox each week.