NYC-WTC_000233286

NYC 9/11 Public Portal Document

(2) This exemption does not relieve the asbestos abatement contractor from the negative pressure equipment requirements on other portions of the same project that require the use of negative pressure equipment. 56-7.9 Heating, Ventilation, and Air Conditioning (HVAC) Systems (a) Isolation. HVAC systems shall be isolated from the regulated abatement work area. Acceptable means of HVAC system isolation include: (1) Shutdown and Isolation. Shutdown and isolation of HVAC systems to prevent contamination and asbestos dispersal to other areas of the building or structure. (2) Local Isolation. Local isolation and provision for temporary HVAC. (3) Positive Pressurization. Positive pressurization of the HVAC system. (i) Positive pressurization shall be restricted to circumstances where HVAC must service the remainder of the building or structure and the HVAC equipment is in the regulated abatement work area or the ducts run through the regulated abatement work area. The appropriate HVAC duct and plenum outlets, inlets and exhaust dampers shall be sealed with caulking and a minimum 3/8-inch thickness plywood, or oriented strand board, or sufficient gauge sheet metal, covered with a double layer of at least six (6) mil fire- retardant plastic sheeting and duct taped airtight. The HVAC duct and plenum joints shall be duct taped airtight. The mixing and balancing damper positions shall be altered and the return fan(s) shall be shut down to produce the required positive pressures. (ii) Project phasing, climate conditions, load conditions and HVAC equipment limitations and controls shall be considered when this alternate procedure is evaluated. Aerodynamics in the duct system, particularly spurs or trunks, shall be considered and, if necessary, the ducts or dampers shall be altered or removed to prevent loss of positive pressure in any part of the system. Precautions shall be taken during abatement activities to insure that the ducts, seals and static pressure lines are not damaged. (iii) The presence of positive pressure shall be demonstrated daily by testing, including days when no Phase II work or support activities are scheduled, and the results must be noted in the asbestos abatement contractor supervisor’s daily project log. Air sampling in occupied, downstream, non-work areas shall be performed on a daily basis as per the requirements of Section 56-7.1 (b)(1) of this Subpart, except days when there are no Phase HA, I IB, or I IC activities. Positive pressure verification shall be done on a continuous basis. The differential pressure shall be easily verifiable by use of a leak free, rigid static pressure taps, static lines on the supply and return ducts and static lines originating in the regulated

12 NYCRR56 Subpart?, Page 64

CITY_21MC100_003235084

NYC-WTC_000233350