Law Department notice on WTC document preservation, Oct 2001

NYC 9/11 Public Portal Document

Study

Mattress Store 2”“ Floor, Northwest comer. Liberty Street

Cleaning Methods: Test 4A - Area air filtration utilizing an air filtration device (AFD). Surface cleaning using a vacuum equipped with HEPA filtration. Nilfisk® Vacuum (CFM 127), AFD 4B - Surface cleaning of horizontal and vertical surfaces using a wet wipe with soap and water. 4C - Carpet cleaning using a commercial carpet wet vacuum with a warm water shampoo solution. “Carpet Express” (Model C-4) 4D - A/C Duct Cleaning. One A/C system located above the suspended ceiling supplies the showroom with air conditioning. The system has two central return grills located imder and adjacent to the air handler. All flexible duct lines were removed and disposed of. Supply diffusers and return grills were removed for cleaning and reinstalled. A professional HVAC cleaning company was contracted to clean the HVAC system in accordance with the following work outline. ■ The workspace was protected using plastic and tape immediately under the duct system and in proximity of the working equipment. ■ Diffusers and return grills were removed. ■ Diffusers and return grills were treated with a degreasing agent. ■ The distribution duct was sealed with a protective barrier to prevent blow back of debris. ■ Diffusers and return grills were washed of degreasing agent and sanitized. ■ The distribution duct and surrounding areas were HEPA vacuumed. ■ The distribution duct openings degreased and sanitized. 4E - Surface cleaning of horizontal and vertical surfaces consisting of wet wipe using water only (vinyl floor tile and window ledge).

Equipment used: Nilfisk® Vacuum (CFM 127), AFD; Carpet wet vacuum, (Model C-4) Filtration status: HEPA Unit Size: 946 sq. ft.; 9,460 cu. ft. AFD Status: Required under methods A and D AFD specification: 400/600 cfin Unit air exchange rate: 23.65 min @ 400 cfin Minimum Air Exchange Required: Every 30 minutes

Unit Description: This 968 sq. ft. mattress showroom faces the WTC Site. An exterior window wall had been blown inward, depositing significant amounts of dust throughout the showroom. Approximately twenty-five mattresses were on display in the showroom. Floor areas were covered with wall-to-wall carpet and padding. A two-foot void space is located above the suspended fibrous tile ceiling. The void space contains an A/C air handling system that is suspended from the wood floor joist construction of the 3"* floor unit. The void space accommodates the sewer drain pipe, electrical and telephone wires, A/C system duct work, and lighting and fire protection systems. The void space contained dust both related to and not related to the WTC attack. Ceiling tiles, flexible ducts, furniture, and display items were disposed of prior to cleaning. 17

NYC-WTC_000145193