Environmental assessment report, 100 Church Street, April 2002

NYC 9/11 Public Portal Document

TRC collected and analyzed eight (8) air samples outside of 100 Church Street. This air sampling was conducted to determine airborne concentrations of target analytes outside of the building in areas NYCLD employees will pass when entering or exiting 100 Church Street and to compare to inside air concentrations. Air sampling of the outside air was conducted for metals, volatile organic compounds, polynuclear aromatic hydrocarbons, polychlorinated biphenyls, mercury, respirable particulates, respirable silica, and dioxin. All outside air samples were found to be either below the detection limit or much less than associated OSHA PELs.

4.0 RESULTS OF WORK PERFORMED BY TRC 4.1 Evaluation of Building Systems TRC met with Mr. Joseph Nunez, Chief Engineer of ZAR, to review and sample the HVAC system serving the NYCLD spaces. The main house fan units serving the NYCLD space on floors 2-6 are located on the 7*^’' floor of 100 Church Street. The fan units serving the Lobby are on the 2"'^ floor. Each floor of the NYCLD space is serviced by a combination of the following three air supply systems:

• Interior air supply system • Perimeter air supply system • Supplemental air system

The core or interior spaces are supplied through 4 supply risers or rectangular ducts that run vertically through all the NYCLD floors. These risers are located in an interior enclosed chase in the northwest, northeast, southwest and southeast sections of the building. Each riser has a dedicated supply fan located on the 7*'' floor. There are 6 return air risers on each floor. All six risers carry the return air to two return air fans located on the 7''' floor. The two return air fans are interconnected through a horizontal duct/airway within the floor fan room. Under normal operating conditions, outdoor air is pulled in through adjustable louvers and prefilters into an airway/ffesh air plenum. Ten to fifteen percent outside air is mixed with return air in a mixing chamber; the air passes through newly installed high efficiency filters (Airguard Variplus VPL- 0495-DOP) and over heating/cooling coils. The conditioned air is then forced by the supply air fans through the supply risers to the tenant spaces located on floors 2 through 15. Air from the supply risers runs along horizontal supply ducts on each floor above the suspended ceiling and through diffusers to individual spaces. Return air is pulled back through return air grilles into the

10

CITY_21 MC100_014586918

NYC-WTC_000176259