Cleaning test ranking table for contaminated areas

NYC 9/11 Public Portal Document

Internal Review Draft

Table 13. Residential Units that are More Heavily Contaminated (Lower Sum of Ranks) Required More Cleaning Events to Achieve the Clearance Criteria

Equal Observable Times Sum of Numeric Mid-point Unit Number Cleaning Test Number Dust Cleaned Ranks Grouping Grouping Grouping 5C significant 3A,.3A,3B 3 13 5A minimal 3B.3B 7 18 2.7 2.7 3C significant lA,iA,3B 18 2.2 3D significant lA.lA 2 20 41) significant 2 A,2 A 2 '22 1.7 4C significant lA 1 23 1.6 minimal 3A T 2? 2A minimal 1B,1B 2 26 1.3 5D significant 3B 1 3? 1.5 3B minimal Scope A 2 34 1.3 3A minimal 2B 1 35 1.7 4A minimal 2A,2A 7 45 N/A

Using the rankings presented in Table 13, a semi-quantitative evaluation was made to detennine if there was a difference in the number of cleaning events needed to met the clearance criteria based on the measured concentrations of pre-cleaning contamination. The average number of cleaning events required to meet the clearance criteria was calculated using several different groupings of the sum of ranks. I’he first set of calculations used numeric breakpoints of 10-19, 20-29, 30-39, and >40. This grouping indicates a decreasing trend in the average number of cleaning events required. The second set ol groupings used the mid-point 23.5. Thus grouping also indicates a decreasing trend in the average number ofcleaning events required. The third grouping used divide the data into equal number of units. Although this grouping suggests a decreasing trend for most of the groupings, the decrease trend did not continue for the last set of data. Overall, it appears that there may be a decreasing trend in the average number ofcleaning events required to met the clearance criteria based upon the degree of pre-cleaning contamination.

Cleaning Equipment Description lA Basic w/o AFD 2A Intermediate wTlEPA w/o AFD 3A Advanced w/o AFD IB Basic w/AFD 2B Intermediate w/HEPA w/AFD 3B Advanced w/AFD

N/A = not applicable

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