The site is a residential property located in Lutherville, Maryland, a northern suburb of Baltimore. The site consists of a single house and its associated property. The property is located within a residential neighborhood.
The presence of mercury has been confirmed inside the home by visual observation and air monitoring.
The owners purchased the house approximately a year ago, having moved into the area after being displaced from their home in New Orleans by Hurricane Katrina.
The source of mercury was a home-made fire detection system that was reportedly installed by the home's original occupant possibly back as far as the late 60's. The detection system utilized a mercury filled J-tube as a mercury switch, in conjunction with a series of pressurized copper tubes attached to heat sensors with a fusibile plug to release the air pressure, hence causing the mercury to move and in turn closing the circuit for the alarm. The system was not operational.
The presence of Mercury was not indicated in the home inspection at the time of purchase and was not known by the current owners until they discovered elemental mercury spilled from the device on December 20th, 2008.
MDE responded to the property on December 20th, and based upon air quality readings and the visible presence of mercury requested that the family evacuate the home. Elemental mercury contamination was observed by MDE personnel in the basement and on the ground floor.
During MDE's initial response the homeowner contacted his insurance company to report the incident and to open a claim. The insurance company considered the matter for approximately 7 weeks, including sending out an industrial hygienist to evaluate the home, before reaching the conclusion that they would not cover the cleanup costs. This message was conveyed to the homeowners at the end of last week.
The homeowners have (2) small children and the wife is of child-bearing age. They have been out of their home since December 20th. Heat has been set on low to minimize vaporization and communication of mercury vapor throughout the dwelling since that time.
The magnitude of the spill is estimated at approximately 1 1/2 pounds onto a hard floor (porous, non-friable asbestos tile). Mercury was also observed on the hardwood steps and flooring of the ground level floor. Additionally, Mercury was observed on and around the furnace, which was located in the immediate proximity to the spill. MDE conducted a gross cleanup of the visible mercury, but was not able to remove all of it due to its distribution throughout the basement and into the cracks of the floors.
On Thursday, February 12, 2009, EPA On Scene Coordinator Ham and START mobilized to the Site and met with MDE and the homeowner. Once permission for access was granted, START conducted additional air monitoring using a Lumex mercury vapor analyzer. Concentrations up to 10,000 ng/m3 were detected in the basement of the residence. Mercury vapor was also detected at elevated levels in the kitchen of the home. Beads of elemental mercury were also visibly present in the area around the furnace, in cracks in both rooms of the basement floor, and on the steps leading up to the first floor. Trace levels of mercury vapor were identified in the remaining areas of the house. Undoubtedly, if the heat were turned up to normal levels, these vapor levels would be much higher.
EPA contractors mobilized to the site on February 17, 2009. A Lumex 915+ mercury vapor analyzer was used to identify the kitchen, the downstairs family room, and the downstairs utility room as the primary source locations of concern. The concentrations of mercury vapor ranged as high as 10,000 nanograms per cubic meter. Mercury beads were visible in the downstairs utility room in multiple areas.
The front hallway and kitchen were vacuumed using a mercury HEPA vacuum. Two mercury beads were identified in the kitchen during vacuum operations. First and second floor rooms were sealed with plastic sheeting across doorways.
Furniture and items on the floor in the downstairs family room were bagged and kept in a conex box which was heated to approximately 70 - 80 degrees Fahrenheit. Items were screened using the Lumex 915+. Any bag with a resulting concentration of less than 1,000 nanograms per cubic meter was segregated to be returned to the home.
The downstairs family room was vacuumed with a carbon filter vacuum using mercury sorbent material and the mercury HEPA vacuum. Readings during this activity identified concentrations greater than 35,000 nanograms per cubic meter of mercury vapor in the room.
Vacuuming of the downstairs utility room has begun using the mercury HEPA vacuum. Mercury beads have been visually identified throughout this area. Items from this room are being bagged for screening. Any bags identified with concentrations greater than 1,000 nanograms per cubic meter of mercury will be heated and ventilated prior to a secondary screening.
The house is not currently being heated above 50 degrees Fahrenheit to minimize spread of mercury vapors throughout the house. The furnace is located in the downstairs utility room. Once this room has been vacuumed, heating and venting of the home may occur.
On Thursday, 2/19/2009, two Regional representatives of the Agency for Toxic Substances and Disease Registry came to the site to observe the cleanup in progress and to discuss the test methods to be used to clear the house for reoccupation. ATSDR will assist EPA with the evaluation of the results.
Vacuuming will continue in the downstairs utility room, along with bagging and screening of any items.
Items that are screened above 1,000 nanograms per cubic meter of mercury will be allowed to vent and rescreened individually.
MercX will be used on the floors in the kitchen, downstairs family room, and downstairs utility room. Heating and venting of the home will occur once all vacuum operations are complete.
The vacuuming and MercX application process may be repeated if needed, based on the vapor concentrations in specific areas of the house.
Confirmation air monitoring using the Lumex 915+ will occur in all areas of the home prior to final clearance via NIOSH analytical method 6009.
|
