4. The combustion riser shall be cleaned using a pressurized air/mechanical brush system in
combination with a vacuum collection device. The direction of cleaning shall be from the
roof down toward the second floor. (It is permissible to use a mechanical brush followed by
application of pressurized air in lieu of combination style equipment.) The vacuum
collection equipment shall be configured to maintain a minimum of 3000 feet per minute air
velocity in the cleaning zone. (See Requirements Section for use of this equipment.)
5. Remove the roof cap if possible and place on a polyethylene sheet. Wet-clean by damp
wiping in place or if removed, spray with Simple Green or a similar environmentally safe
degreaser and hand wash as needed to remove adhered materials.
17
NYC-WTC_000145221
OCR can misread numbers and units. Confirm readings against the page image before using them.
NYC-WTC_000145221Source: NYC Law Department, mirrored locally
Document excerpt acknowledging contributors and outlining the collaborative scope of an EPA environmental protection study regarding the World Trade Center site.
EPA Region 2 letter regarding revised environmental work plan submission for two buildings including asbestos, health, and safety assessment components.