A2Z received an emergency response call
from International Steel Group regarding a mercury spill in
a pit at High Head #2 Pumping Station. An estimated 6 to 10
fluid ounces of mercury had spilled out of a broken flow gauge.
A2Z sent their field chemist to survey the spill. A crew was
dispatched to begin cleanup using a Minuteman MRS-3 Mercury
Vacuum. The levels of mercury vapor measured at the man way
of the pit were so high that the confined space attendant had
to wear a respirator in order to keep an eye on the entrant
without being exposed to the vapors.
The pit entrant, wearing a level “B” (Supplied
Fresh Air) suit vacuumed up all visible mercury from the floor
and disposed of all loose debris and dirt from the pit. After
a second and third vacuuming, mercury indicator powder was
sprinkled onto the floor to find any traces. The space was
ventilated throughout the day using two fans and ductwork in
order to create air changeovers. After applying the indicator,
the space was closed up and left to sit overnight. The crew
returned to check the powder and vacuum up any mercury indicated.
The mercury had been on the concrete floor long enough to corrode
the surface and coat it. A wire brush was used to remove the
coating and mercury amalgamator was used to gather any small
beads created by this process. The space was again ventilated
throughout the day. A level gauge was removed from the pit
that contained several pounds of mercury. It was disassembled
and disposed of.
An additional 4 to 6 ounces of mercury
were found in a sump. The sump contained several inches of
water and sludge. A2Z used a shop-vac to vacuum up the water
sludge. The mercury was left behind to be removed with the
MRS-3 Mercury Vacuum.
After the mercury was removed, the pit
was still showing high levels of vapor. After ventilating the
pit for 30 minutes new readings were taken. It was decided
to install a ventilation fan on the stove pipe. While the ventilation
fan was on, levels were below the TWA (time weight average).
ISG instructed workers that had to enter the pit to ventilate
the pit for thirty minutes before entering. ISG decided to
bring the controls above ground and stop entry altogether.
