Environmental Engineering Reference
In-Depth Information
that are known or presumed to contain asbestos, their activities are also
regulated by OSHA. These activities are described as Class III asbestos work.
In such activities, service workers must wear, at a minimum, a half-mask
NIOSH-approved respirator, and the building owner must have a respiratory
protection program in place. Required work practices include isolating the
work area; using plastic drop cloths where appropriate; and carefully clean-
ing up on work task completion using wet techniques, HEPA vacuuming,
and proper waste disposal.
2.
Repair
Asbestos-containing materials that have experienced limited damage can be
easily repaired. Thermal system insulation applied to steam and hot water
lines, as well as to boiler surfaces and steam condensate tanks, is commonly
repaired. Such repairs may involve patching damaged surfaces with wetta-
ble cloth materials similar to those normally used to enclose ACM-contain-
ing TSI. It may also include removing short pieces of TSI using glove bag
procedures. Repairs are regulated by OSHA as Class I asbestos work.
Because of the significant engineering and work practice requirements,
repairs are best conducted by abatement contractors using trained asbestos
workers and supervisors.
3.
Enclosures
Physical barriers can be used to enclose friable ACM to minimize its distur-
bance and asbestos fiber release. The use of enclosures, as recommended by
USEPA, involves the construction of a nearly airtight barrier around ACM.
Enclosures are a useful asbestos control measure when ACM is located in a
small area or when the total area of ACM enclosed is small. They are inap-
propriate where water damage is likely and where damage or entry to the
enclosure may occur.
Enclosures have the potential advantage of minimizing disturbance and
associated fiber release from some ACM applications at relatively low cost
(compared to removal). However, ACM remains and will eventually have
to be removed on building demolition or renovation. Enclosures require
periodic inspection for potential damage.
In theory, any physical barrier that reduces the potential for asbestos
fiber dispersal into building spaces can be described as an enclosure.
Because suspended ceilings are not airtight and are subject to entry by
building service personnel, use of a suspended ceiling as an enclosure is
not recommended. When a suspended ceiling serves as a base for a return
air plenum, it may, in some measure, reduce the potential for fiber dispersal
from that area into building spaces below. However, some released asbestos
fibers may become entrained in the low-velocity flows that are characteristic
of return air plenums. Removal of ceiling tile under damaged, friable ACM
may result in a significant fiber release episode into the building space
below.
Search WWH ::




Custom Search