EPA review letter, 133-135 Greenwich Street

NYC 9/11 Public Portal Document

at ground level and EPA requested that this station be moved further west to be located in front of 21-23 Thames Street. Now Airtek is proposing to locate this station on the sidewalk bridge. Based on the September 7, 2005 site walk, this third monitoring location may be located on the sidewalk bridge through the Abatement Phase and for only a portion of the Demolition Phase. Once the demolition of the 21-23 Thames Street reaches the third level (i.e., parallel to the street bridge), the monitoring station located on top of the sidewalk bridge will need to be brought down to street level in front of 21-23 Thames Street. EPA believes it would be beneficial for Airtek to relocate the street bridge monitoring station during appropriate times when no work is being performed at the buildings.

Agreed. Please see Section 3.2 paragraph 2.

Subsection 3.3 Abatement Work Air Monitoring

6. Need to add "Phase" after "Abatement" for the reference to Table 3 in the second paragraph.

Done.

Table 1- Community Air Monitoring

7. Footnote 2: Remove the second "below" at the end of the footnote.

Done.

Table 1- Community Air Monitoring - Notes on Community Air Monitoring Table - Dust

8. During the 4 Albany demolition, we found poor correlation between Met One 9012 results and the PM2.5 TEOM. The Met One E-BAM (with a heated inlet to address condensible emissions) was found to correlate well with the TEOM and was utilized for continuous PM2.5 monitoring in place of the Met One 9012. The Met One 9012 was used for PMIo sampling only. We do not believe the Met One 9012 is appropriate for PM2.5 monitoring. The Met-One E-BAM, R&P TEOM, or Met-One BAM 1020 would be acceptable alternatives. Revise this section and Table 1 to specify which of the three aforementioned instruments will now be used.

The section states that the Met One E-BAM will be used. The BAM 1020 will be usedfor data comparison. Table 1 and notes have been edited.

9. Since Airtek indicates in its response to EPA comment # 34 that the parameters specified in Table 1 will be sampled during both the abatement and demolition phase, the last two sentences of this paragraph need to be revised to indicate that the equipment will be operated for at least one week before the Abatement Phase and that the results will be

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NYC-WTC 000134345