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Paul Brady- Freezer of Fill
by Imelda and Francis Murphy
 By
all accounts, it's unlikely that in 1994, Professors at Bolton Street
College of Technology, thought that one of their graduates would
use his engineering degree to figure ways to freeze soil in Boston.
But that is one of the tasks Paul Brady is doing years later- now-
as Shift Engineer in charge of Tunnel Jacking and Ground Freezing.
He is employed by Slattery/White a major contractor on the Big Dig.
Paul
was born in Dublin 32 years ago and has journeyed far, to work below
the street of Boston and en route he contributed to that French
engineering marvel, Disneyland Paris. Paul says he learns as he
goes. His college would be proud.
Paul's
work is located near South Station - a railway, subway and bus depot
in Boston, with a distinctive brown stone facade. Its back is to
the Fort Point Channel. South Station and environs are built on
fill placed there at an earlier juncture in Boston's history - fill
that expanded the city into Boston Harbor.
That
fill, however, is not conducive to tunneling in that as the diggers
burrow the surrounding walls disintegrate into the excavation. The
attendant danger is that nearby structures, including skyscrapers
and the railway station above, will collapse as the soil beneath
them gives way.
The
engineering solution, simply put, is two fold: first, give the earth
more staying power by freezing it; second, push concrete structures
that are self supporting into the excavated hole.
Paul
implements this solution by overseeing the network of piping that
pumps a frigid solution below ground around the area to be excavated.
Also, he oversees the pushing- the tunnel jacking- of huge structures
into the tunnel as it is excavated.
In
three feet increments the fill is clawed at by machinery, scooped
up, transferred to the end of the pit, where it is placed in containers
that are hoisted out by crane, then emptied into massive trucks
to be hauled off site.
Meanwhile
the pre-cast tunnel sections are pushed methodically in place, through
the frozen soil, and the tunnel grows…at Paul's direction.
©
Copyright Francis and Imelda Murphy
All rights reserved
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