NYC 9/11 Public Portal Document
horizontal surfaces on building facades. For some buildings, building facades facing the street
were cleaned while the facades at the rear remained dirty. The observed debris was characteristic
of the debris from the WTC collapse of September 11, 2001.
Samples collected from various buildings indicated that some of the debris contained asbestos
containing material. Other samples did not disclose the presence of asbestos, and others were
trace or below 1% asbestos. In the absence of sampling data for specific buildings, it is
recommended that NYS DOL licensed asbestos contractors with NYC DEP and NYS DOL
certified workers perform the clean-up activities. In addition, an independent third party must
perform air monitoring during the clean-up activities. This activity is necessary to address
concerns by the community of re-entrainment of ambient dust to the interior of buildings. Wet
methods and HEPA vacuums will be used for cleaning roofs, terraces, and other outside areas of
the buildings.
Costs to Cleanup 250 Buildings
Area Size # Buildings Costs/Sq ft Building Costs
10,000 sq. ft 25 $3 $750,000
5,000 sq. ft 50 $4 $1,000,000
1000-5000 sq. ft 175 $8 $3.500.000
$5,250,000
Air Monitoring Costs $200,000
Facade Cleaning Costs (includes contingency costs) $5,000,000
Total Costs $10,450,000
3) Provide Indoor Cleaning and Sampling for Residences/Commercial Buildings where
contamination may still exist
Ambient sampling results do indicate that the source of contamination is disappearing from the
WTC site, since the fires are extinguished and recent sampling results rarely indicate any
elevated levels. Federal, State, and New York City agencies are confident that the methods of
cleaning (e.g., wet wipes, HEPA-vacuums) recommended to residences and commercial
buildings are appropriate. However, it is also known that these methods are not always 100%
effective, and that there will be instances where apartment owners and commercial facilities will
not clean up as recommended.
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NYC-WTC_000153003
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