Removal of drums from the Stacked Drum Area of the Drum Disposal Area Completed

Air Monitoring Protocol Modification

In September 2000, EPA announced its Record of Decision for addressing source areas at the Ciba-Geigy site.  The source areas are contaminated areas that have released or could release contaminants to the groundwater underlying the property.  The plan recommended by the EPA included Off-Site Treatment/Disposal of Drummed Material and On-Site Ex-Situ Bioremediation of contaminated soils.

On November 22, 2004, Ciba Specialty Chemicals (Ciba), under the oversight of the U.S. Environmental Protection Agency (EPA), completed the removal of buried drums from the Stacked Drum Area within the Drum Disposal Area.  The Stacked Drum Area is an unlined area of the site that was used from 1972 through 1977 for the disposal of drums of waste material generated during the production of dyes and resins.  Based on test pit investigations, EPA had estimated that 35,000 drums were stacked from one to four layers deep in this area. 

The first drum was removed from the Stacked Drum Area on December 9, 2003, and the removal process was completed on November 22, 2004, after 47,055 drums were removed.  Although more drums were found than originally estimated, EPA and Ciba were committed to removing all drums found in the Stacked Drum Area.  In addition, the drum removal operation was completed well ahead of the anticipated 18 month schedule.  While all drums have been removed from the Stacked Drum Area, it is expected that additional drums of waste material will be found while excavating other portions of the Drum Disposal Area and other source areas.  Any drums of waste material encountered during the remaining cleanup work will be disposed of in the same manner as those found in the Stacked Drum Area.   The off-site shipment of drum material from the Stacked Drum Area will continue for approximately one month.

In addition to the drum disposal operation that has recently been completed, approximately 287,000 cubic yards of soil will be treated on site using a bioremediation process using bacteria that already exist in the soil to break down and ingest contaminants.  This component of the remedy was begun on July 6, 2004 and is expected to continue for up to six years. 

During drum removal operations, air monitoring was performed at six locations around the perimeter of the Site for 24 hours a day, seven days a week.  This continuous monitoring was performed to insure that excavation activities were not affecting air quality at the perimeter of the site.   During drum removal, excavation activities occurred each week, however, contaminated soil for the bioremediation process is excavated approximately one week a month.  EPA has approved a modification to the perimeter air monitoring schedule based on this reduced excavation schedule.   Air monitoring at the perimeter of the site will continue for those weekends/holidays that follow an excavation week and for 24 hours each work day.  Perimeter monitoring will be discontinued on weekends/holidays that do not follow an excavation week.