Virginia Law

A. Set up.

1. Ensure that the area inside the enclosure is visibly clean of all ACM, dust and debris, that spray encapsulant utilized for lockdown purposes has dried, and that the negative air system is and remains fully operational at a rate of one air change per hour.

2. For each 1,000 square feet of negative air enclosure space, initially agitate the air with an electric leaf blower for at least five minutes, agitating the air on all horizontal and vertical surfaces. Activate at least one stationary fan for each 10,000 cubic feet of enclosure volume with the stationary fan angled toward the ceiling. Keep the stationary fan(s) operational for the duration of the sampling.

3. Place the air pumps and sampling cassettes such that each covers approximately the same square footage of floor area, and the exposed filter faces of the sampling cassettes are oriented approximately 45 degrees from the horizontal, using tape and clips as necessary to position the sampling cassettes.

4. Start the air pumps and sample for the required time, turning off the air pumps and then the stationary fan(s) when finished.

B. Number of samples.

The minimum required number of sample cassettes for each enclosure site is listed in the tables below (each set of samples consists of inside samples, ambient air samples, field blanks, and a sealed blank):

* For areas greater than 10,000 square feet, the number of inside air samples to be obtained will increase by one sample for each 5,000 square feet over 10,000 square feet. For example, using TEM an enclosure of 30,000 square feet would require nine inside samples, five ambient air samples, two field blanks, and one sealed blank, for a total of 17 samples in the set.

1. Field blanks required. Not less than 10% of the total inside air sample cassettes, or a minimum of two per set. The cap of each cassette is to be removed for not more than 30 seconds and replaced (before inside and ambient air sampling is initiated) at the following places:

a. Near the entrance to each abatement area, and

b. At one of the ambient sites.

2. Sealed blanks required. One sealed sample cassette blank shall be included with each sample set submitted for analysis.

C. Sampling times.

The run time for each air pump is calculated by dividing the flow rate (lpm) of the pump into the number of liters of air required to be collected (1,000 liters minimum for PCM analysis, 1,199 liters minimum for TEM analysis) to obtain the required number of minutes.

D. Recording.

A floor plan indicating the locations of the collected sample cassettes, along with a data sheet indicating the project name, project monitor, location of project, date samples were collected, calibrated flows for each air pump, start and stop times for each air pump, the preferred method of analyses specified, and the calculated number of liters drawn for each cassette sample, shall be transmitted to the laboratory with the cassette samples to be analyzed. The inclusion of these documents is necessary when generating reports on final clearance air sampling for the project.

E. Shipping.

Air sample cassettes shall be shipped in separate containers from bulk samples. To prevent sample cassette contamination, avoid using expanded polystyrene because of its static charge and particle-based packaging materials.