Environmental assessment report, 100 Church Street, April 2002

NYC 9/11 Public Portal Document

Ten (10) of the initial round of fifty-eight (58) samples from the HVAC system contained a level of asbestos that exceeded the individual sample target post-cleaning concentration of 10,000 str/cm^. The ten samples were located as follows: • Southeast supply duct on the 6*^*’ floor, • Southwest return duct on the 2"'’ floor, • Southwest ceiling tile on the 20* floor, • Air handler supply #11 on the 21®* floor, • Return air duct #F 12 on the 21 floor, • Air handler supply#! on the 2 floor, • Air handler supply #2 on the 7* floor, • Air handler supply #3 on the 7* floor, • Air handler supply #4 on the 7* floor, and • Supplemental supply air handler in the LAN room on the 20* floor.

In response to this and the lead results described in Section 4.4.3, ZAR hired a National Air Duct Cleaning Association (NADCA) certified duct cleaning contractor to re-clean and encapsulate the interior supply ducts, supply risers, return ducts and risers, and re-clean the HVAC fan units serving the NYCLD spaces. The building has reported that once the cleaning is complete for the NYCLD space, the remaining interior HVAC units and ductwork supplying air for the remainder of the building will be re-cleaned as well.

The HVAC re-cleaning effort was performed by Branch Services (Branch), Gunningham Mechanical (Cunningham), and Indoor Air Professionals (LAP). Branch is a New York State certified asbestos abatement contractor and Cunningham and lAP are NADCA certified duct­ cleaning contractors. Branch conducted power-washing of fan units and Cunningham and LAP performed duct cleaning activities. Branch applied an encapsulant to the HVAC system surfaces subsequent to HVAC cleaning. Encapsulating is the process of applying of a thin layer of sprayed liquid material that creates a membrane locking down any residual dust subsequent to cleaning operations. Cleaning activities utilized HEPA filtered equipment and followed NADCA protocols.

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