-My name is Audrey Tepper.
I'm the historical architect
for the National Mall
here in Washington DC.
And I'm here today
giving you a little tour
of a construction contract for
the Thomas Jefferson Memorial.
We are replacing a series
of roofs on the Memorial.
There are two flat roof
sections,
one that circles the dome
and one that goes over
the colonnade.
We call that the upper roof
that circles the dome,
and the lower roof
that circles the colonnade
or the row of columns --
or the ring of columns
that goes around the Memorial.
-That's okay.
-And the roof below these
marble tiles has failed,
and we actually have to lift
the marble tiles off the roof
for the very first time
since they were constructed.
The portico roof --
the portico roof tiles --
had been in place
since the time of construction,
and the portico roof itself,
the tiles are in good condition,
however,
they do have
biofilm growing on them.
So, we will remove those tiles
for the first time
since construction,
bring them down to the ground,
clean them,
do some miscellaneous repairs.
In the meantime, when that roof
is exposed,
we're going to replace
the waterproofing
below the marble tile.
It was --
The National Park Service
first noticed it in 2006,
and it's really grown
pretty aggressively since then.
You see sort of dark
and light patterns
of the biofilm
growing on the surface,
and we are going to be
using specialized lasers
to remove the biofilm
from the surface.
We also will have masons
working.
We're going to be repointing
faulty mortar joints on the dome
and elsewhere
on the Memorial.
