On Thursday, July 17, 2008, the Merrimack Fire Department (MFD) and the New Hampshire Department of Environmental Services (NHDES)responded to a release of elemental mercury that occurred at the Merrimack High School, located at 38 McElwain Street, Merrimack, NH.
The release occurred in the nurse’s room when the janitorial crew while cleaning accidentally broke a blood pressure measuring instrument. The crew attempted to clean up the visible mercury with a dry mop. This process however, caused further migration of the spilled mercury and cross contamination to other school areas.
On July 17, 2008, at approximately 7:00 pm the Merrimack Public School Department mobilized its cleanup contractor, Clean Harbors Environmental Services (Clean Harbors) to conduct mercury air monitoring and perform the cleanup. Clean Harbors hired Covino Environmental Associates, of Woburn, MA, to conduct the air monitoring and initiated the cleanup operations using mercury granular absorbents and mercury vacuums. The janitorial crew that came in contact with the mercury was sent to hospital for medical evaluation. Their shoes were taken by the MFD for disposal. The NHDES also notified the EPA’s Emergency Planning and Response Branch (EPRB) of the spill, and requested assistance for the following day to provide mercury monitoring to confirm Clean Harbor’s readings.
On July 21, 2008, the NHDES notified OSC Hatzopoulos that they requested Clean Harbors and Covino Environmental to collect 8-hour time weighted average air samples for laboratory analysis.
On August 1, 2008, the NHDES notified OSC Hatzopoulos that the laboratory analysis of the air samples did not reveal mercury levels that would prohibit re-occupancy of the school. However, for an additional level of comfort, the NHDES requested EPA to re-survey the school and confirm the laboratory results prior to re-occupancy of the school.
On August 4, 2008, OSC Hatzopoulos and Weston, arrived at the school to conduct the air monitoring with the Lumex Mercury Vapor Analyzer. Present was the Director of Maintenance of the Merrimack School District. Approximately 30 floor locations and 15 breathing zone locations were surveyed. Three measurements were taken from each location. The highest level of mercury detected from all of the the locations was 23 nanograms per cubic meter (ng/m3). These levels are well below the ATSDR's re-occupancy standards. OSC Hatzopoulos notified the ATSDR, NHDES and the School Department of the survey results and demobilized from the incident scene.