NYC-WTC_000232249

NYC 9/11 Public Portal Document

discretion of the Environmental Consultant and as daily site conditions may dictate, additional mercury readings may be taken.

5.5 Mercury (Vapor/Gas)

A separate sampling and analysis method is required for mercury, as field studies have indicated that atmospheric mercury is generally greater than 95% in the vapor phase. An iodated carbon trap will be analyzed for total elemental mercury (particulate associated/vapor) using cold vapor atomic fluorescence (CVAF). The carbon trap is a proven and sensitive method for detecting trace ambient levels of atmospheric mercury. To collect the mercury sample, a high volume pump will be attached to the carbon trap and set at a flow rate of approximately 4 liter per minute.

5.6 Respirable Dust and Crystalline Silica

Respirable dust and crystalline silica sampling will be performed according to NIOSH Method 0600 protocol with analysis following NIOSH Method 7500 (XRD).

5.7 Semivolatile Organics (PCDDs/PCDFs, PAHs, PCBs)

Each site will have two (2) General Metal Works (GMW) model PS-1 high volume air samplers to collect 24-hour samples of PAH, Dioxin/Euran and PCBs, following USEPA Method TO­ IS A, TO 9A, and TO-4A, respectively. One sampler will be used for PAHs. A second sampler will be use for both PCBs and D/Es. Method TO-13A, TO4A, and TO-9A use the PS-1 samplers to draw air through a sampling train consisting of a 102 millimeters diameter microquartz filter first to collect the semivolatile PAH particulates and then a glass cylinder holding a polyurethane foam (PUE) plug (1 inch of XAD-2 adsorbent resin is used in the middle of the PAH sampling media) to collect the semivolatile vapors. The entire sampling train (filter, XAD-2, and PUE plugs) are extracted together and analyzed for speciated PAH, PCBs, and D/Es compounds using gas chromatography/mass spectrometry. The samplers will be set to run at approximately 250 liters per minute resulting in a total air volume of 360 m^ over the prescribed 24-hour sampling period.

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