NYC-WTC_000195194

NYC 9/11 Public Portal Document

At times during the project, the laboratory chose to perform analyses on samples that were neither requested by EPA nor specified on the Chain of Custody. This was most evident in the case of wipe samples that were collected for total dust. The QAPP required the collection of one pre­ cleaning and one post-cleaning sample for total dust from each unit. These samples (wipes) also served as the samples used for the analysis of crystalline silica (alpha-quartz, cristobalite, tridymite, calcite and gypsum). The crystalline silica sample was also collected pre-cleaning and post-cleaning; however, it was collected from three locations in the unit. Upon submitting the samples to the laboratory, specific direction was provided to the lab regarding which samples were to be analyzed for total dust. The laboratory however, chose to prepare all three samples for the total dust analysis rather than prepare the samples specified on the chain of custody.

A mercury vapor investigation was conducted as part of the study. The mercury vapor investigation was conducted using a Lumex* analyzer’^ that revealed a mean mercury vapor concentration of 53.6 ng/m’ (range 3-210 ng/m’), demonstrating that air samples within the building tested below EPA's Reference Concentration of 300 ng/m', A statistical evaluation of the results of the mercury vapor investigation is presented in Attachment K, Summary ofMercury Vapor Results using the Lumex^ Vapor Analyzer.

(Note: The following section does not include data and discussion of wipe sampling results for alpha-quartz, calcite, gypsum, cristobalite, tricfymite and total dust. The analytical results for these parameters were uncertain thereby rendering these data unusable.)

Discussion ofAnalytical Results by Building Area

Unit 2A - This unit is located on the second floor. It is a 1,335 sq. ft. loft with one bedroom facing Cedar Street. The unit has hardwood floors. The unit presented minimal dust accumulation in the dwelling with the exception of the baseboard-heating units. The windows were not blown in. All personal items were disposed except for a couch and chairs.

Cleaning Method - The unit was cleaned using Test IB. use of a Ridgid® shop vacuum and Hoover® upright vacuum for vacuuming the floors and other surfaces. Neither vacuum was equipped with a HEPA filter. An AFD was used during the cleaning process. In addition, all horizontal surfaces were wet wiped. This cleaning method was used for each cleaning event.

Cleaning Results - The unit met the primary clearance criteria listed in Table 1.0 for each compound after being cleaned twice.

Asbestos Before Cleaning Samples - Pre-cleaning micro vacuum and wipe samples were collected for asbestos. These samples indicate that asbestos was present in the unit prior to cleaning. Three of the four micro vacuum samples detected chrysotile. All five wipe samples detected chrysotile, although two of the samples were below the detection limit.

'^The instrument has a detection limit of 2 ng/m’.

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