EPA work plan review, 133-135 and 21-23 buildings, August 2005

NYC 9/11 Public Portal Document

Part II - Environmental Community Monitoring Plan 133-135 Greenwich & 21-23 Thames Streets Airtek Project 05-0701— Rev I August 11, 2005

o Check of flow rate (quarterly) o Audit by collocation with a portable FRM sampler. • Measures of Precision: o Check of flow rate (every 2 weeks)

o Collocation (see below). • Collocation: o Monitors have a second monitor collocated at the same site, rotated between sites.

o The second ("duplicate") sampler runs every 6 days. o Collocated particulate samplers must be less than 4 m apart but more than 1 m apart. The PM2,5 sampler requires enhanced quality control measures because of its unique design and operational attributes. Examples of these QC measures include: • Filter equilibration temperature control of +/-2 °C over 24 hours • A pre-sampling filter weighing within 30 days of sampling period • Retrieving the filter from the sampler within 96 hours of collection • A post-sampling filter equilibration and re-weighing within 240 hours after the sampling period

The precision check for manual methods is based on a comparison of the concentrations measured by two samplers that collected data side-by-side during the same specific time period. To ensure that the two collocated samplers duplicate similar conditions during monitoring specific rules are enforced: The two collocated PM2.5 samplers must be within 4 meters of each other and particulate matter samplers must be at least 1 meter apart to preclude airflow interference. This 1-meter separation is based on the low volume of sampling. Currently, the PM2,5 FRM monitors have a sampling volume of 16.67 L/min. At low concentrations, agreement between the measurements of collocated samplers, since they are expressed as percent differences, may be relatively poor. For this reason, collocated measurements are selected for use in the precision calculations only when both measurements are above 6 g/m3 for PM2.5. The accuracy check for manual methods involves checking the flow rate of the sampler each calendar quarter.

3.5 Quality Assurance for Gaseous Pollutants These are some of the measures AIRTEK staff take to ensure the quality of data from the continuous gas analysis systems. A "monitoring system" for a given pollutant at a given site usually consists of an inlet tube (called a "probe"), an automatic electronic analyzer and a data acquisition system (possibly connected to multiple instruments) and/or a strip chart recorder.

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