we’ve had about three billion gallons of
raw or combined sewage that would
discharge on an annual basis from our
combined sewer systems about two-thirds
overflows into the Anacostia River about
a third of it goes into the Potomac
River our program is to capture that so
we’re about to go into the third of the
tunnel here we’re about to go up onto a
mile to the heavier machine
overhead you can see the big air
ventilation system bringing fresh air in
so it’s a fairly simple process that the
shield has a main bearing unit that has
drive motors that turn this cutter head
and that cutter head is digging into the
ground simultaneously the machine is
advancing into the ground so as this is
spinning machines advancing forward and
ingesting material then it stops and the
crew builds a ring inside of the tail
shield that tail she’ll has a seal
that’s on the backside of it and that
keeps the ground and water and grout and
stuff from invading the tunnel
so as it advances its pulling material
out of this group conveyor for that
complete advance that’s getting mixed up
into a mixture of soil and water and
solution and then getting pulled up all
the way to the conveyor belt and that
conveyor belt then takes the material
out to the shaft where it’s dumped into
big boxes and wasted up the shaft now
it’s ready to excavate again so it
starts the cycle all over
[Music]
this machine has around 100 millimeters
and minutes that’s about four inches per
minute so it can theoretically do a six
foot push in about 18 minutes we have
sewage overflows into the Anacostia
River Potomac and Rock Creek that causes
water quality problems we’re going to
reduce the overflow volume by 96 percent
[Music]
raw or combined sewage that would
discharge on an annual basis from our
combined sewer systems about two-thirds
overflows into the Anacostia River about
a third of it goes into the Potomac
River our program is to capture that so
we’re about to go into the third of the
tunnel here we’re about to go up onto a
mile to the heavier machine
overhead you can see the big air
ventilation system bringing fresh air in
so it’s a fairly simple process that the
shield has a main bearing unit that has
drive motors that turn this cutter head
and that cutter head is digging into the
ground simultaneously the machine is
advancing into the ground so as this is
spinning machines advancing forward and
ingesting material then it stops and the
crew builds a ring inside of the tail
shield that tail she’ll has a seal
that’s on the backside of it and that
keeps the ground and water and grout and
stuff from invading the tunnel
so as it advances its pulling material
out of this group conveyor for that
complete advance that’s getting mixed up
into a mixture of soil and water and
solution and then getting pulled up all
the way to the conveyor belt and that
conveyor belt then takes the material
out to the shaft where it’s dumped into
big boxes and wasted up the shaft now
it’s ready to excavate again so it
starts the cycle all over
[Music]
this machine has around 100 millimeters
and minutes that’s about four inches per
minute so it can theoretically do a six
foot push in about 18 minutes we have
sewage overflows into the Anacostia
River Potomac and Rock Creek that causes
water quality problems we’re going to
reduce the overflow volume by 96 percent
[Music]
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