Kingston Ash Slide
Early Emergency Response Air Monitoring
As part of the emergency response activities immediately following the spill, TVA brought in its own air monitoring personnel and equipment to work with a respected emergency response contractor to assess the impacts of the spill and the response on the ambient air quality. A variety of equipment and techniques were employed to quickly describe air quality impacts.
TVA’s contractor, The Center for Toxicology and Environmental Health (CTEH), began monitoring with hand-held instruments on December 28, 2008. These instruments instantly measured the concentration of particles in the air. Typically 200-400 readings were collected every day with these instruments. These instruments measured particulates smaller than 10 microns in size (PM10).
CTEH also began sampling at four locations on 12/28/08. The term “analytical air sampling” refers to air sampling methods that involve collection of air samples over a specified period, followed by analysis at a laboratory. The results of these samples represent the average airborne concentration for the sample period. These methods typically involve passing a known volume of air through a collection medium (e.g. charcoal sample tube or filter cassette) that efficiently traps and retains the compound until it can be analyzed by the laboratory. By knowing the volume of air collected, and the quantity of chemical absorbed onto the collection medium, the average air concentration can be calculated.
The filters from the temporary stationary monitors were analyzed for 21 metals, as well as quartz as Constituents of Potential Concern. Based on potential toxicity, eight metals were selected for reporting: arsenic, beryllium, cadmium, chromium, lead, selenium, thallium, and vanadium. All of the concentrations were below the detection limits, except for one sample with a low concentration of cadmium and three samples with low concentrations of lead. These concentrations do not pose a health concern, since they are below the Agency for Toxic Substances and Disease Registry (ATSDR) acute minimal risk level for cadmium and below the National Ambient Air Quality Standard for lead. View these sampling results.
On January 1, 2009, the original four air monitoring locations were identified to be within the work zone, and 5 new locations for analytical sampling were established at the perimeter of the work zone. Locations of the five new community air monitors were selected by a team consisting of CTEH, TVA, EPA, and Roane County Emergency Management Agency. A sixth station was established to reflect background air quality at a representative location some distance west of the TVA ash spill.
TVA placed a temporary mobile laboratory just south of the ash pond from Jan. 2 to Feb. 3, 2009. This laboratory measured particulates smaller than 2.5 microns using two different measurement techniques; a tapered element oscillating microbalance (TEOM) and a filter based method. The TEOM offered real time measurements of PM2.5, and the filter based method yielded a 24-hour average. PM2.5 data gathered using the mobile laboratory is linked below. The graph below shows the 24-hour average fine particle (PM2.5) concentrations by the two instruments. The hourly TEOM readings were averaged to calculate the 24-hour value. All daily particulates measured were well below the 24-hour National Ambient Air Quality Standard of 35 micrograms per cubic meter.
In addition to the PM2.5 measurements, TVA collected PM10 samples for chemical analysis. Samples from both filter based PM2.5 and PM10 instruments were analyzed for constituents of concern. Concentrations of all samples which were above detection limits are shown in graphical form below. Airborne concentrations of arsenic, cadmium, chromium, lead, selenium, thallium and vanadium on-site at Kingston were all within the lower end of the range of background concentrations in the United States.
The bearing and relevance of these results are discussed on the Constituents of Potential Concern Web page.
The four original on-site monitoring stations were shut down on Feb. 4, 2009, because the area was being prepared for on-site storage of dredged ash. Monitoring was moved to the new perimeter sites.