August 27, 1990

Mr. A. M. Mickey Fine
Industrial Hygienist
Salt River Project
Post Office Box 52025
Phoenix, Arizona 85072-2025

Dear Mr. Fine:

This is in response to your letter of March 12, to the Occupational Safety and Health Administration (OSHA), regarding negative pressure glovebag issues. Your letter was transferred from our Phoenix Area Office to us for a reply. We apologize for the delay in response.

OSHA allows the use of glovebags for small-scale short-duration operations. Generally, these operations are maintenance type activities involving removal of small amount of asbestos. We require the establishment of negative pressure enclosures for large-scale jobs to prevent the spread of asbestos contamination beyond the work area and to protect bystanders from excessive asbestos exposures. The negative air bag was determined to meet the intent of a negative pressure enclosure.

The use of serial glovebagging or repeated use of one glovebag is discouraged because of the increased risk of breakage of these bags, which would cause gross contamination. Therefore, we cannot agree with your statement that if a glovebag is safe for three linear feet, this procedure repeated several times is still safe.

In our July 5, 1989, letter to Brand Company, OSHA reviewed Brand Company's work procedures and approved them under the condition that all other provisions of the asbestos standard are met including air monitoring, designation of a competent person, etc. We require a decontamination facility to be constructed near the work area so that the employees, if they are accidentally contaminated with asbestos wastes through breakage of the glove bag, malfunction of the vacuum, or electric failure, can quickly decontaminate themselves.

We appreciate your concerns and agree with you that there are difficulties associated with the use of negative-pressure glovebags. However, Brand Company has not sent us any updated work procedures; therefore, we cannot provide comments on any new methods they might have developed since July, 1989.

We recognize that there are inherent problems in any abatement procedures. We place emphasis on proper work practices and engineering controls as a means to reduce employees' exposures. Workers must be trained to be aware of health hazards of asbestos and to work safely, following proper work practices. We do not endorse the method of negative pressure glovebag or any other method, but merely have accepted its use as meeting the intent of a negative-pressure enclosure. We prefer a full containment under negative-pressure; however, the standard does not specifically require such containment. The use of a negative pressure glovebag is simply one acceptable alternative.

OSHA is proposing some changes to the asbestos regulations and will be addressing the issues of small-scale, short-duration operations and negative-pressure enclosures. The proposal was published in the Federal Register on July 20. A copy is enclosed. We welcome public comments and certainly will take your comments into consideration.

If we can provide you with further assistance, please do not hesitate to contact us.

Sincerely,

Patricia K. Clark Director
Designate Directorate of Compliance Programs

Enclosure

DATE: April 13, 1990

MEMORANDUM FOR: PAT CLARK, DIRECTOR DESIGNATE

Directorate of Compliance

FROM: GABRIEL J. GILLOTTI Assistant Regional Administrator Office of Technical Support

SUBJECT: Feasibility of Glovebag Usage

Attached is a letter received from Arizona OSHA regarding the glovebag method. A very large project is underway in that state and the Salt River Project's Industrial Hygienist is questioning the process.

I would appreciate it if you would provide guidance in this matter given that the questions relate to background decisions and the initial endorsement by OSHA of this method.

cc: Derek Mullins

Attachment

SALT RIVER PROJECT

POST OFFICE BOX 52025
PHOENIX, ARIZONA 85072-2025
(602)236-5900

March 12, 1990

Division of Occupational Safety & Health The Industrial Commission
800 West Washington Street
Phoenix, Arizona 85007-2922

Attention: Derek Mullins Administrative Coordinator

Dear Derek:

Per our previous conversation, I would like clarification on the following negative pressure glovebag issues.

We have conducted area and personnel monitoring during glovebag operations with and without the use of negative air. In both cases fibercounts were well below the OSHA action level. This being the case, why go through the added expense and additional time to utilize the negative air glovebag?

If OSHA agrees that a glovebag is safe for 3 linear feet (or procedures involving one 42" glovebag) then why don't they recognize that this safe procedure repeated several times is still safe?

Following BRANDS original outline of negative air glovebag procedure to Federal OSHA, a hole should be slit in the glovebag for make-up air. OSHA agreed with this procedure without any exposure monitoring conducted. What if the suction is lost due to malfunction of the vacuum, electric failure, etc.? How do you assure that fibers will not escape through this hole?

I contacted BRAND with my concerns, and they sent me an updated procedure. This involves lowering the pressure on the vacuum and there is no allowance for make-up air. There are inherent problems with this procedure as well, since the bag collapses while you work. The negative air vacuum may be reduced so the bag collapses more slowly, however, work that requires more detail (valves) make the job more difficult to complete prior to the bag collapsing.

At the end of a negative glovebag job, you can let the vacuum pump suck the remaining air out of the bag prior to sealing it. There is no need for a HEPA vacuum. What happens if the bag were to fall off the pipe or a hole was put in the bag? The small vacuum pump may not be able to pull enough air to collect all the fibers and it is not designed to vacuum pieces of asbestos containing material. This would lead to a potential asbestos exposure.

The encapsulant used to seal the pipe at the end of the job, as well as the surfactant used for wetting during the removal has the tendency to be sucked down the hose to the vacuum, requiring the need for a trap in line. The added expense to draw a negative pressure (the vacuum pump, a pressure regulator, and a moisture accumulator cost $850), the extra time it takes to set up the operation and monitoring which indicates that this procedure provides no additional protection makes the negative pressure glovebag a futile effort.

Thank you for addressing these issues of concern. I look forward to your response.

Sincerely,

A. M. Mickey Fine Industrial Hygienist

AMF/sm