NYC-WTC_000231403

NYC 9/11 Public Portal Document

Jciearunce Air Monitoring; Employment of aggressive sampling techniques with a volume of air collected detenoine the airborne concentration of residual fibers and shall he performed as the final abatement •activity. I eLAP: Environmental Laboratory Approval Piogiam administeted by tire New York State Deparunent of P Health, r EPA or USEPA: United States Environmental Protection Agency.

Homogeneous Work Area: Portion of the Work Area that contains one type of ACM and/or where one type of abatement is used.

Phase Contrast Microscopy: “PCM” shall mean the measurement protocol for the assessment for the fiber content of air. For PCM analysis, the clearance air monitoring shall be considered satisfactory when every sample is less than or equal to 0,01 ffee or ths background concentrations, whichever is greater.

Polarized Light Microscopy: ‘‘PLM”shall mean the measurement protocol for the assessment for the asbestos content of bulk materials. For PLM analysis, the New York City and EPA Regulatory limit is 1.0%,

Transmission Electron Microscopy: “TEM”shall mean the measurement protocol for the assessment for the asbestos fiber content of air. For TEM analysis, the clearance air monitoring shall be considered satisfactory when the requirements stated in 40 CFR Part 763, Subpart E, Appendix A, Section TV are met. For the purposes of our testing the regulatory limit is 70 asbestos structures per mm2.

4.0 Scope of Work 4.1 Bulk Sampling Procedures

ALC’s licensed technicians worked under the guidance provided by the EPA guidelines for asbestos-in Buildines: Simplify Samplins Scheme for Friable Surfacine Matenals." This sampling procedure uses random sampling to ensure that the samples are representative of the sampling area, ALC’s inspectors;

1. Identified all friable surfacing materials and grouped them into homogenous sampling areas by floor 2, Prepared diagrams of each sampling area 3. Determine the number of samples to collect (9 samples per homogenous areas are recommended) Determine sampling locations 4. Collect samples 5, Fill out chain of custody 6. Send samples to a qualified laboratory

Due to the insufficient amount of dust and debris in the apartment units and public areas of the building, we were unable to collect the optimum number of samples suggested in the above referenced guidelines.

Upon completion of the initial assessment and bulk sample collection. ALC determined that there were elevated asbestos levels in one apartment. With the guidance of the above referenced document and NYCDEP we went back to each floor and assessed each apartment on each floor for visible dust and debris.

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CITY_21MC100_008879972

NYC-WTC_000231406