460
T. Meschede and R. Vogelsberger
Phase B consisted of the construction of the new electrolysis membrane plant,
of the shutdown of the old electrolysis units and the rehabilitation of those
portions of the facility that were reused in the new membrane plant.
Phase C involved the decontamination and, where appropriate, the demolition
of contaminated equipment, the electrolysis units, and related structures. The
two existing cell houses were dismantled and demolished, and all contaminated
soil and concrete surfaces from the plant (above 10 mg Hg/kg) were excavated
and replaced with clean materials. Metals and equipment with no or low
contamination were reused or scrapped. The contaminated waste materials are
placed in the off-site landfill. An extensive monitoring program for the
classification of dismantled and demolished materials, the quality control, and
the final verification of site cleanup had been implemented.
A particular feature of the decontamination project was the use of cutters and
cranes to dismantle the heavily contaminated cell houses in a piece-by-piece
manner, along with water sprays for dust suppresion. This technique was
selected over conventional methods of demolition via explosives or wrecking ball
because of the reduced potential for the spread of mercury contaminated dust
and fumes. The excess spray water was collected and - together with the cleaning
water from the cleaning pad and vehicle wash - treated before discharge.
All loose soil and rubble was solidified in concrete blocs to minimize mercury
losses during storage, transport, and filling into the landfill. The handling of the
concreted materials was easier than that of loose rubble. For example,
conventional cranes and trucks could be used for transportation and packing.
The measurement and quantity control of processed contaminated rubble and
soil could be done by simply counting the blocs.
Also, the release of mercury vapors from contaminated materials could be
reduced considerably by concreting. However, during the hot summer season it
was found that mercury vapor levels in the close vicinity of the concreted blocs
were still too high in comparision with maximum allowable work-place
concentrations. Therefore, work was discontinued during daytime hours and
the transportation and landfilling of the concrete blocs is executed only during
the cooler night shifts.
5
Health and Safety
Throughout the project, extensive measures were foreseen to protect the health
and safety of the workers, especially with respect to potential exposures to
mercury. Personal protective equipment was available and routine monitoring of
working conditions is conducted, as well as periodic medical examinations of the
work crews. In addition, all of the personnel received an extensive introductory
training on health and safety and frequent updates and refresher courses. The
specific procedures for avoiding and minimizing potential mercury hazards were
detailed in a comprehensive Health and Safety Plan developed for this project.
T. Meschede and R. Vogelsberger
Phase B consisted of the construction of the new electrolysis membrane plant,
of the shutdown of the old electrolysis units and the rehabilitation of those
portions of the facility that were reused in the new membrane plant.
Phase C involved the decontamination and, where appropriate, the demolition
of contaminated equipment, the electrolysis units, and related structures. The
two existing cell houses were dismantled and demolished, and all contaminated
soil and concrete surfaces from the plant (above 10 mg Hg/kg) were excavated
and replaced with clean materials. Metals and equipment with no or low
contamination were reused or scrapped. The contaminated waste materials are
placed in the off-site landfill. An extensive monitoring program for the
classification of dismantled and demolished materials, the quality control, and
the final verification of site cleanup had been implemented.
A particular feature of the decontamination project was the use of cutters and
cranes to dismantle the heavily contaminated cell houses in a piece-by-piece
manner, along with water sprays for dust suppresion. This technique was
selected over conventional methods of demolition via explosives or wrecking ball
because of the reduced potential for the spread of mercury contaminated dust
and fumes. The excess spray water was collected and - together with the cleaning
water from the cleaning pad and vehicle wash - treated before discharge.
All loose soil and rubble was solidified in concrete blocs to minimize mercury
losses during storage, transport, and filling into the landfill. The handling of the
concreted materials was easier than that of loose rubble. For example,
conventional cranes and trucks could be used for transportation and packing.
The measurement and quantity control of processed contaminated rubble and
soil could be done by simply counting the blocs.
Also, the release of mercury vapors from contaminated materials could be
reduced considerably by concreting. However, during the hot summer season it
was found that mercury vapor levels in the close vicinity of the concreted blocs
were still too high in comparision with maximum allowable work-place
concentrations. Therefore, work was discontinued during daytime hours and
the transportation and landfilling of the concrete blocs is executed only during
the cooler night shifts.
5
Health and Safety
Throughout the project, extensive measures were foreseen to protect the health
and safety of the workers, especially with respect to potential exposures to
mercury. Personal protective equipment was available and routine monitoring of
working conditions is conducted, as well as periodic medical examinations of the
work crews. In addition, all of the personnel received an extensive introductory
training on health and safety and frequent updates and refresher courses. The
specific procedures for avoiding and minimizing potential mercury hazards were
detailed in a comprehensive Health and Safety Plan developed for this project.