EPA review letter, 133-135 Greenwich Street

NYC 9/11 Public Portal Document

Part II - Environmental Community Monitoring Plan 133-135 Greenwich & 21-23 Thames Streets Airtek Project 05-0701— Rev 2 September 16, 2005

The gravimetric analysis system consists of a laboratory balance and a human analyst trained to operate it. The weighing should take place in controlled temperature and humidity. Before being weighed, both unexposed and exposed filters must be conditioned for at least 24 hours in this environment.

The unexposed and exposed sample filters are transported in their cartridges to reduce the chance of contamination. Traceability of standards:

The following records of traceability, certification, etc. will be checked and maintained, along with criteria for the various calibrations, and audits:

o flow: orifices certified against a NIST-traceable displacement meter

o pressure drop: manometers certified NIST-traceable annually

o masses and balances NIST-traceable

o temperature and pressure NEST-traceable

• Calibrations: The sample collection staff performs a multi-point flow calibration of each particulate sampler using an orifice unit (quarterly, after maintenance or repairs and when indicated).

• Precision checks through collocation: A second sampler is placed the monitoring station.

• Performance audits:

o Quarterly audits: An IH Quality Coordinator does a one-point flow audit quarterly on all samplers, using a different orifice unit than the one used to calibrate the sampler.

• Data audit: Data Manager reviews all the data for anomalies.

3.4 Quality Assurance for PM15 Measures of accuracy, precision, and additional measurement quality objectives for PM2.5 measurements are summarized on Table A-2. These are measures to ensure the quality of data gathered using manual samplers of PM2.5. A manual PM2.5 monitoring system consists of a sampling system at the site, an analysis system at a central location and a transportation system to get the sample filters from one to the other.

The sampling system consists of a sampler (one or more at each site) with attached temperature and pressure instruments and a human operator who loads new (unexposed) filters into the sampler, programs it to sample each filter for 24 hours (normally midnight to midnight) on a specified day, and retrieves the exposed filters afterward. "Sequential" samplers may be used, capable of automatically changing filters to sample for several days in a row. Sequential samplers can run continuously, except for maintenance and QA checks.

The gravimetric analysis system consists of a microbalance in a climate-controlled weighing room and a human analyst trained to operate it. The weighing must take place within a narrow

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NYC-WTC 000134256