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Air Quality Monitoring of the Hunting Tower Demolition

Demolition Operation Facts

  • Crane demolition of the northern Hunting Towers building commenced on December 16, 2002;
  • Crane demolition was complete by the end of February 2003;
  • Crushing of material was concentrated through mid-March 2003 with light crushing continuing through April 4, 2003;
  • Only hauling of material remains today for the Hunting Tower demolition task.

Air Emissions Monitoring Program Facts

The Program included a two-prong approach: Air Emissions Monitoring at the demolition site by a certified professional and continuous Air Quality monitoring units stationed around the site.

Air Emissions Monitoring

  • The dedicated environmental inspector was trained and certified through EPA’s Air Emission Testing Course. The course requires that professionals pass written and field exams which certify proficiency in visually measuring dust in the air produced by a localized source.
  • The inspector was on site, full-time, during demolition and crushing activities and was equipped with a cell phone and radio in order to contact the contractor, the Construction Engineer, the Environmental Construction Manager, and others, as needed, to rapidly resolve any issues.
  • The evaluations completed depict an average opacity of 7.9%. Monitoring and evaluation forms were completed only when dust was being produced on site. We targeted an average of 10% while typical opacity limits on other projects include on-site limits of up to 20% and property line limits of up to 15%.
  • Only a few of the evaluations produced a value over 10%. This inspector worked with the contractor to increase water application and shift demolition operations on the few occasions that dust levels increased.

Air Quality Testing

  • The second component of the program included an air emissions monitoring program with multiple air monitoring devices sited in strategic locations in proximity to the demolition activities.
  • These instruments, including units stationed on the roof of vacant Building D1 of the Hunting Towers Complex, the roof of St Mary’s School, and a location in Jones Point Park, continually collected data which was downloaded and analyzed by air emissions experts. Due to changing conditions, the St. Mary’s School unit was left for the longest duration.
  • The monitoring units collect particles suspended in air which, at certain levels, may be harmful to human health. The target particles, in accordance Federal and State regulations, are 10 microns in diameter and less (referred to as PM10).
  • The National and State Air Quality Standard (NAAQS) for PM10 is a maximum of 150 micrograms per cubic meter for a 24-hour average concentration.
  • Our monitoring indicated that levels recorded in the vicinity of the demolition activities were well below this standard. In fact, only a few readings exceeded 1/3 of that standard (50 micrograms per cubic meter) and those were recorded at night while demolition activities were dormant. For examples, relatively elevated readings were recorded during the President’s Day snow event, indicating increased emissions from heat producing sources.
  • As depicted on the following graphs for December 2002-March 2003, most readings ranged from 10-35 micrograms per cubic meter. No reading approached or exceeded 150, at any time.
  • Levels recorded during demolition activities showed no significant change when compared to recordings taken prior to demolition, as depicted in the December 2002 report.
  • According to our experts, this data correlates well with permanent air quality monitoring stations around the City of Alexandria and Fairfax County.