EPA interim final report on WTC background study, April 2003

NYC 9/11 Public Portal Document

September 4,2002 - One apartment and the common area were sampled; access was denied to the second apartment unit. Microvacuum samples could not be collected from the common area, due to absence of a porous surface. The common area ceiling wipe sample was collected from the duct work above dryer #3 as the ceiling had a rough stucco surface which was not suitable for wipe sampling.

September 5,2002 - The common area was not sampled since the access agreement was not signed.

September 6,2002 - Microvacuum samples could not be collected in one apartment and the common area from carpets/rugs or drapes as none were present. Ceiling samples could not be collected in the common area due to the presence of a rough surfaced drop ceiling.

September 10,2002 - A common area was not available for sampling.

September 12,2002 - Couch/chair microvacuum samples could not be collected from the apartment. Samples from the common area could not be collected due to restricted access.

September 24,2002 - Microvacuum samples could not be collected from the common area due to absence of a porous surface.

September 25,2002 - High flow air sampling pumps in the common area shut down for twenty minutes due to power outage in part of the building. Sampling time was extended twenty minutes to compensate for loss of volume. Air sampling was terminated 110 minutes early in one unit at the request of the owner. The owner was called out for the remainder of the day.

6.0 ANALYTICAL RESULTS AND DEVELOPMENT OF BACKGROUND CONCENTRATIONS The samples collected during this Study were analyzed to determine the concentration of each analyte in the matrix in which it was collected. The purpose of collecting and analyzing the samples was to establish background concentrations for a select group of compounds that have been identified as contaminants related to the collapse of the World Trade Center. As stated previously, these background concentrations will be used to supplement the health-based benchmarks established in the "World Trade Center Indoor Air Assessment: Selecting Contaminants of Potential Concern and Setting Health-Based Benchmarks"document and may be used as an alternative cleanup value if the health-based benchmark cannot be achieved.

6.1 Methods Deriving a background concentration for each analyte was completed using the following guidance; Guidance for Characterizing Background Chemicals in Soil at Superfimd Sites (EPA 540-R-01-003, June 2001), Role of Background in the WORLD TRADE CENTER BACKGROUND STUDY 19

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