Air sampling protocol document, 130 Cedar Street, Jan 2005

NYC 9/11 Public Portal Document

130 Cedar Street July 15, 2004 Selective Demolition and Façade Restoration Koenen Associates

a. Comply with requirements for paint removal. b. Repeat application up to two times if needed.

3. Remove asphalt and tar with solvent-type paint remover.

a. Apply only to asphalt and tar by brush without prewetting. b. Allow paint remover to remain on surface for 10 to 30 minutes. c. Rinse off with [cold] [hot] water using low-pressure spray. d. Repeat application if needed.

F. Water Spray Applications: Unless otherwise indicated, hold spray nozzle at least 6 inches (150 mm) from surface of masonry and apply water in horizontal back and forth sweeping motion, overlapping previous strokes to produce uniform coverage.

G. Steam Wash: Apply steam to masonry surfaces at pressures not exceeding 80 psi (550 kPa). Hold nozzle at least 6 inches (150 mm) from surface of masonry and apply steam in horizontal back and forth sweeping motion, overlapping previous strokes to produce uniform coverage.

H. Chemical Cleaner Application Methods: Apply chemical cleaners to masonry surfaces to comply with chemical cleaner manufacturer's written instructions; use brush or spray application methods, at Contractor's option. Do not spray apply at pressures exceeding 50 psi (345 kPa). Do not allow chemicals to remain on surface for periods longer than those Indicated or recommended by manufacturer.

I. Rinse off chemical residue and soil by working upward from bottom to top of each treated area at each stage or scaffold setting. Periodically during each rinse, test pH of rinse water running off of cleaned area to determine that chemical cleaner is completely removed.

1. Apply neutralizing agent and repeat rinse, if necessary, to produce tested pH of between 6.7 and 7.5.

J. After cleaning is complete, remove protection no longer required. Remove tape and adhesive marks.

3.8 CLEANING BRICKWORK

A. Cold-Water Wash: Use cold water applied by [low] [medium] [high]-pressure spray.

B. Cold Water Soak:

1. Apply cold water by intermittent soaking. 2. Use perforated hoses or other means that will apply a fine water mist to entire surface being cleaned. 3. Apply water in cycles with at least 30 minutes between cycles. 4. Continue water application until surface encrustation has softened sufficiently to permit its removal by water wash, as indicated by cleaning tests. 5. Remove soil and softened surface encrustation from masonry with cold water applied by low-pressure spray.

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CLAY MASONRY RESTORATION AND CLEANING 04901 -12

NYC-WTC 000125179