NYC-WTC_000232639

NYC 9/11 Public Portal Document

Final Report 125 Cedar Street, NYC, NY

yielding a more consei-vative recalculated TEF.

Mercury This analytical method is a cold-vapor atomic absorption method and is based on the absorption of radiation at the 253.7-nm wavelength by mercury vapor. The mercury is reduced to the elemental state and aerated from solution in a closed system. The mercury vapor passes through a cell positioned in the light path of an atomic absorption spectrophotometer. Absorbance (peak height) is measured as a function of mercuiy concentration.

Wipe sampling Results

The clearance wipe criteria for each of the following analytes were achieved in accordance with project specifications.

• Lead in settled dust, <25|ag/fF • PAHs in settled dust, <0.3 mg/m’ • Dioxin in settled dust, <4ng/m’ • Mercury, between 1 and 2 mg/m“

The attached appendices contain all laboratory analysis information.

Conclusions

Based on project oversight, including results of air sampling and wipe sampling data collected, it is the professional opinion of ATC that all cleaning at 125 Cedar Street, New York, New York was conducted in accordance with the project manual as well as all applicable federal, state and local asbestos regulations. All ambient and final air clearance and wipe sample results were found to have a concentration satisfactory to achieve the acceptable criteria established by the NYCDEP and EPA standards for re­ occupancy following cleaning activities. Cleaning of the contaminated areas was deemed acceptable upon achieving NYCDEP and USEPA defined primary clearance levels. The primary clearance levels for this project were defined as:

• Dioxin in settled dust, <4ng/m- • Lead in settled dust, <25gg/ff • Asbestos in air, 0.0009 f/cc PCMe

In addition to the primary clearance levels, secondary clearance levels were utilized to determine the need of additional cleaning. However, secondary clearance level analytical results did not warrant such additional cleaning. Our professional services have been performed, our findings obtained and our recommendations prepared in accordance with customary principles and practices in the

ATC Project No. 15.22906.0002 Pages

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