NYC-WTC_000195194

NYC 9/11 Public Portal Document

«r detection limits and below the primary clearance and secondary numeric criteria. w Dioxin Before Cleaning Samples - Four pre-cleaning wipe samples were collected and analyzed for dioxin. The results indicate that there was dioxin present; however, the TEQ concentration for each sample was below the primary clearance criterion of 4 ng/m\ w Post P‘ Cleaning Samples - Four post-cleaning wipe samples were collected and analyzed for dioxin. The results indicate that the concentrations of dioxin detected were similar to the pre-cleaning samples and that the TEQ concentrations for each sample were well below the primary clearance criterion of 4 ng/m". Because the dioxin samples were below the primary clearance criterion for all of the samples collected, no additional samples were collected for analysis of dioxin.

Gypsum Before Cleaning Samples - Pre-cleaning air samples were not collected.

Post P‘ Cleaning Samples - Two air samples were collected after the first cleaning. Gypsum was not detected in any sample. Because gypsum was below the detection limits for all of the samples collected, no additional samples were collected for analysis of gypsum.

w Lead Before Cleaning Samples - Three micro vacuum samples and four wipe samples were collected. The results indicate that all three micro vacuum samples were below the detection limit and at concentrations below the comparison value of 25 pg/tt”- Two of the four wipe samples had detectable concentrations of lead; however, they were below the primary clearance criterion of 25 pg/ft^. The third sample was below the detection limit. The fourth sample was lost at the laboratory and was not analyzed.

Post P‘ Cleaning Samples -Tiwo air samples, three micro vacuum samples and four wipe samples were collected after the first cleaning. The two air samples were below the primary clearance criterion of 1.0 pg/m^. All three micro vacuum samples and one of the four wipe samples were below the detection limit. Two wipe samples were below the primary clearance criterion and the fourth wipe sample was above the primary clearance criterion. Due to the one lead sample being above the primary clearance criterion, as well as the asbestos samples that exceeded the primary clearance criterion, this unit was cleaned a second time.

Post 2”“^ Cleaning Samples - Two lead wipe samples were collected after the second cleaning in the area where the post-first cleaning lead exceedance occurred. One of the samples was received broken at the laboratory and was not analyzed. The other sample was below the detection limit and below the primary clearance criterion. The results from the second cleaning indicate that the cleaning technique was effective in removing the elevated concentration of lead that was observed after the first cleaning.

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NYC-WTC_000195245