United States
Environmental Protection
Agency
Risk Reduction
Engineering Laboratory
Cincinnati OH 45268
Research and Development
EPA/600/S2-89/047 Jan. 1990
&ERA Project Summary
Observational Study of Final
Cleaning and AHERA
Clearance Sampling
John R. Kominsky, Ronald W. Freyberg, James A. Brownlee,
James H. Lucas, Jr., and Donald R. Gerber
A study was conducted during the
summer of 1988 to document final
cleaning procedures and evaluate
Asbestos Hazard Emergency
Response Act (AHERA) clearance air-
sampling practices used at 20
asbestos-abatement sites in New
Jersey. Each abatement took place In
a school building and Involved
removal of surfacing material, ther-
mal system insulation, or suspended
ceiling tiles. Final cleaning practices
tend to be similar among abatement
contractors. Meticulous attention to
detail in cleaning practices is im-
portant to a successful final cleaning.
Sites passing a stringent, "no-dust"
criterion of a thorough visual inspec-
tion are more likely to pass the
AHERA TEM clearance test. AHERA
sampling and analytical requirements
and recommendations are not com-
pletely understood and followed by
consultants conducting clearance air
monitoring.
This Project Summary was devel-
oped by EPA's Risk Reduction Engi-
neering Laboratory, Cincinnati, OH, to
announce key findings of the research
project that is fully documented in a
separate report of the same title (see
Project Report ordering information at
back).
Introduction
As required under the AHERA of 1986,
the U.S. Environmental Protection
Agency (EPA) has issued a final rule
regarding inspections, abatement, and
management of asbestos-containing ma-
terials in schools (October 30, 1987; 52
CFR 41826). The final rule specifies a
clearance sampling protocol for deter-
mining when an asbestos-abatement site
is clean enough for the critical contain-
ment barriers to be removed. It further
specifies the phase-in of transmission
electron microscopy (TEM) as the ana-
lytical method to be used on air samples
taken for clearance monitoring.
The final cleaning phase of an abate-
ment project is paramount to achieving a
successful abatement as defined in the
AHERA final rule. Final cleaning applies
to the phase of the abatement project
that occurs after all visible asbestos-con-
taining material has been removed from
the substrate; the substrate has been
brushed and wet-wiped; a sealant has
been applied to the substrate and to
plastic sheeting covering the floors, walls,
and fixed objects to "lock-down" any
invisible fibrils that might remain; and all
plastic sheeting (excluding the critical
containment barriers) has been removed.
The final cleaning phase of the abate-
ment involves the detailed cleaning of
surfaces in preparation for final visual in-
spection and AHERA clearance sampling.
The Risk Reduction Engineering Labor-
atory of the EPA conducted a study to
document the final cleaning procedures
and evaluate AHERA clearance sampling
practices used at different asbestos-
abatement projects. This report presents
the observations made at 20 asbestos-
abatement projects in New Jersey during
the summer of 1988.
-------
Procedures
Although selection of the 20 asbestos-
abatement projects was based largely on
availability, each site also met the fol-
lowing criteria:
1. Each abatement project was in a
school building.
2. The abatement project involved (a)
removal of sprayed- or troweled on
surfacing material; (b) removal of
thermal system insulation of mechan-
ical equipment (i.e., boilers, tanks,
heat exchangers, pipes, etc.); or (c)
removal of suspended ceiling panels.
3. The abatement project was governed
by written specifications that were to
comply with the minimum require-
ments of the State of New Jersey,
Asbestos Hazard Abatement Sub-
code (N.J.A.C. 5.23-8) and EPA
guidance for work practices and pro-
cedures to be used m performing
asbestos-abatement projects.
4. The abatement project was to be
cleaned and cleared in accordance
with the sampling protocol specified
in the AHERA final rule (October 30,
1987;52CFR41826).
A site documentation form provided the
following information for each abatement
project:
1. The abatement area's use (class-
room, corridor, boiler room, etc.) and
dimensions.
2. The type (acoustical plaster, ceiling
panels, pipe insulation, etc.) and
quantity (square feet or linear feet) of
asbestos-containing material (ACM)
abated, and type and percentage of
asbestos in the ACM.
3. Final cleaning procedures and work
practices.
4. Performance of negative-pressure air
filtration systems including the static
pressure differential across critical
containment barriers and the airflow
of each air filtration unit.
5. Results of final visual inspections
conducted by the asbestos safety
technician and/or inspector from the
Asbestos Control Service (ACS) of
the New Jersey Department of
Health, including reasons why the
visual inspection failed.
The background information describing
the abatement area, the ACM abated, and
other miscellaneous information was ob-
tained by interviewing, at each site, an
asbestos safety technician (AST) certified
by the New Jersey Department of Com-
munity Affairs and employed by an
Asbestos Safety Control Monitor (ASCM)
firm. The ASCM firm is hired by the
school district or Local Education Agency
(LEA). The AST continuously monitors
and inspects the asbestos abatement
project in accordance with the Asbestos
Hazard Abatement Subcode (N.J.A.C.
5:23-8). The AST must be on the job site
continuously during the abatement pro-
ject to ensure that the work is performed
in accordance with the regulations specif-
ied in the Asbestos Hazard Abatement
Subcode.
A site documentation form was also
used to document the following AHERA
clearance practices used at each site:
1. Conditions of sampling, i.e., aggres-
sive versus nonaggressive sampling,
use of fans to maintain air turbulence
during clearance air sampling, etc.
2. Air sampling methods, i.e., filter
medium, cassette type, flow rate, etc.
3. Performance of negative-pressure air
filtration systems, including the static
pressure differential across critical
containment barriers and the airflow
performance of each air filtration unit.
Airflow and Static Pressure
Differential
The airflow performance of the air
filtration units operating during both the
final cleaning and AHERA clearance
phases of the abatement was measured.
The air velocity of the rectangular air-
intake face of each air filtration unit was
measured to estimate the airflow
performance of the units. The air-intake
face was divided into 16 equal rectan-
gular areas, and the velocity was meas-
ured at the center of each area. The air
velocity was measured with a calibrated,
constant-temperature, thermal anemom-
eter. The static pressure differential
across the critical containment barriers
was measured at each site during both
the final cleaning and AHERA clearance
phases of the abatement. The static pres-
sure differential (inches of water) was
measured with a calibrated, electronic,
digital micromanometer.
Quality Assurance of AHERA
Clearance Data
Clearance of each abatement site was
based on the analyses of the final clear-
ance air samples collected by the AST.
The analyses were obtained from the
laboratory report contained in the final
project report prepared by the ASCM
firm. The analysis of the samples and the
corresponding quality control and quality
assurance procedures were specified by
the contract with the performing analyt-
ical laboratory to be conducted in
accordance with the requirements i
AHERA final rule. The conditions of
pling and the sampling procedures
by the AST were documented for
parison with the requirements specifi
the AHERA final rule.
Results and Discussion
Site Description
Sixteen of the 20 abatement pro
involved general occupancy areas (c
rooms, offices, recreational rooms,
ridors, etc.); three involved boiler re
and mechanical equipment rooms;
one involved both types of areas.
ACM abated at 13 of the project
involved surfacing material (sprayec
troweled-on), 8 involved thermal sys
insulation on mechanical equipn
(pipes and boilers), 3 involved both
facing material and thermal system i
lation, and 2 involved suspended ce
tiles. The ACM contained chrysc
asbestos (from 2% to 93%) at
projects, amosite asbestos (from 2°A
10%) at 2 projects, and both chrysi
(from 10% to 75%) and amosite (f
30% to 40%) at 1 project.
Ventilation and Static Pressun
Differentials
Air-intake volumes for each hii
efficiency particulate air (HEPA) filtral
unit in operation during final cleaning <
AHERA clearance sampling were me
ured at each of the 20 sites. Seven
ferent models were observed and eve
ated. The average operating airflow
each model was compared with I
manufacturer's nominal airflow, i.e., i
manufacturer's advertised rated pe
capacity. Actual average operating airfl
ranged from 50% to 80% of the nomii
airflow for seven models. The reduc
airflow performance of the filtration un
is probably due to the increased sta
pressure associated with extended a
obstructed exhaust duct conditions and
increased particulate loadings on t
filters. The significance of this reduci
operating flow rate is in the procedu
used to determine the number of a
filtration units necessary to achieve tl
desired minimum ventilation rate (i.<
four air changes per hour). Th
assumption that the air-filtration units a
operating at the manufacturer's specific
nominal airflow rate could result in actu
ventilation rates significantly belo
project design specifications.
Despite the lower-than-assumed ver
tilation rates of the observed HEP/
-------
iltration units, enough units were used at
ill but one site to achieve a minimum of
four air exchanges per hour during
AHERA clearance sampling. Also, only
two sites failed to meet the recom-
mended air-exchange rate during final
cleaning. Actual air-exchange rates
ranged from 2 to 13/h during final clean-
ing and 3 to 13/h during AHERA
clearance sampling.
Static pressure differential across the
containment barriers was measured at
one or more test locations at each of the
20 abatement sites during both final
cleaning and AHERA clearance sampling.
Eight of the 20 sites showed an average
static pressure differential of at least
-0.02 in. of water during final cleaning.
Nine sites showed an average pressure
differential of at least -0.02 in. of water
during AHERA clearance sampling. The
average static pressure differential for all
sites ranged from -0.03 to -0.01 in. of
water during both final cleaning and
AHERA clearance sampling.
Continuous monitoring of the static
pressure differential across the contain-
ment barriers was conducted at only one
site. Ventilation smoke tubes were
typically used at the beginning of each
work shift at all abatement sites to verify
visually that the containment enclosure
remained under negative pressure (i.e., a
noticeable inward movement of air
existed through the decontamination
facility).
Final Cleaning Work Procedures
and Practices
In this study, final cleaning began at
each project site after the encapsulated
plastic sheeting was removed from the
walls, floors, and fixed objects. The
critical barriers, windows, doors, and
heating, ventilation, and air-conditioning
(HVAC) vents remained sealed. The air-
filtration units remained in service.
Table 1 presents a matrix of the final
cleaning procedures and work practices
used at the 20 asbestos-abatement sites.
At two abatement sites (Sites E and J),
aggressive cleaning techniques were
used. Aggressive cleaning involves
sweeping the surfaces with the exhaust
from a hand-held 1-horsepower leaf
blower to dislodge any residual debris,
and then allowing the airborne particulate
to settle. Aggressive cleaning was con-
ducted at Site E after the site had failed
the first AHERA clearance attempt and
before it was recleaned; and at Site J
after the walls and other surfaces had
been sprayed with water and allowed to
dry and after hard-to-reach areas such as
indented corners, crevices around doors
and windows, etc., had been cleaned with
a vacuum equipped with a HEPA filter.
The sequence and nature of the
cleaning tasks seemed to depend on the
substrate from which the ACM was
removed (e.g., concrete ceiling versus a
T-bar grid system for suspended ceiling
tiles) or on the structural makeup (i.e.,
concrete walls, wood floor in a gym-
nasium, etc.) of the abatement area. Final
cleaning usually began by spraying the
walls, plastic critical containment barriers,
and other surfaces with a water mist to
remove any loosely bound debris. The
resultant asbestos-containing water on
the floor was gathered into pools by use
of a rubber squeegee or (less frequently)
with push-type brooms. The bulk of the
pooled water was scooped up with
plastic-bladed shovels. The water was
placed in double-layered, 6-mil-thick,
asbestos-disposal bags, which generally
contained plastic that had been removed
from the walls and floors or protective
clothing that had been used by the
workers. The residual water removed with
a wet vacuum was also placed in the
disposal bags. At one site, a commer-
cially available gelling agent was also
added to the disposal bag to gel the
water to minimize the potential for its
subsequent release during storage.
At two sites, some of the wash water
penetrated the seams between the floor
tiles and caused them to buckle. These
buckled floor tiles were sporadically dis-
tributed throughout the abatement areas.
At both sites, the asbestos-containing
water beneath the floor tiles was allowed
to dry, and the tiles were not repaired as
part of the abatement. These areas could
be potential sources of airborne asbestos
fibers when repaired later by mainten-
ance personnel.
Although to a lesser extent than the
spraying of surfaces with water, some
final cleaning began with the scraping or
brushing of the substrate to remove any
visible debris.
The surfaces, particularly hard-to-reach
areas such as indented corners, crevices
around doors and windows, floor-wall
junctures, etc., were then cleaned with a
HEPA-filtered vacuum. At several sites,
final cleaning began with the HEPA-
vacuuming of surfaces.
The vertical and horizontal surfaces
were then wet-wiped with amended
water. The contractors reportedly pre-
pared the amended water solution by
mixing approximately 1 or 2 oz. each of
50% polyoxyethlyene ester and 50%
polyoxyethylene ether in 5 gal of water.
The elevated horizontal and vertical
surfaces were usually wiped first, and
then all the other surfaces. All the
surfaces except the floors were wiped
with cotton rags, paper towels (bath size),
or a sponge dampened with amended
water. Several abatement contractors
said they did not use cotton rags or
sponges because their repeated use
increased the potential for smearing
residual particulate on the surfaces being
cleaned. Although the paper towels were
sometimes reused, such reuse appeared
to be markedly less than that observed
for cotton rags or sponges at other sites.
Deterioration appeared to be the primary
factor that prompted a worker to discard
a paper towel. A bucket of amended
water was either used by a single worker
or shared by several workers and the
same bucket was used for both rinsing
and dampening of the rags or paper
towels. The workers did not wipe the
surfaces in any one direction. The cotton
rags, paper towels, or sponges were not
replaced frequently, especially during the
cleaning of elevated and hard-to-access
surfaces. Nor was the amended water
changed frequently.
After the walls, windows, and other
surfaces had been wet-wiped, the last
step in the final cleaning involved a
complete mopping of the floors with a
clean mop head wetted with amended
water. The floors were mopped once at 7
of the sites and twice at 13 of the sites.
The mop heads were changed infre-
quently. No changes in the water were
observed during this procedure at any of
the sites.
Before the floors were mopped a
second time at four of the sites, the
plastic sheeting covering the air-filtration
units and a plastic sleeve that covered
the associated flexible exhaust ducts
were removed. Both coverings had been
installed before abatement work began.
According to the contractors, this practice
simplified the cleaning of this equipment,
particularly the flexible exhaust ducts.
At all sites, wastewater from the wet-
wiping and mopping operations was
treated as asbestos-containing water and
placed in double-layered, 6-mil-thick,
standard asbestos disposal bags. These
standard asbestos disposal bags which
contained wastewater were not placed in
leak-tight containers. The wastewater in
the disposal bags was solidified with a
gelling compound at one of the 20 abate-
ment sites. The rags, paper towels,
sponges, mop heads, and other materials
used during final cleaning were also
placed in these bags. The bags were not
-------
1
c
S
0
c
C
*_
o
!R
3
1
1
CO
1
Q
5
I
-
00
^ C*3 ^f- IO
CO »- CM TJ- 10
^- CO ^J*
.CM -CO „ „
(^ T^ CO ^h IO
T- r\j co TT
** c^ c*y ^t"
i- CM CO
T- CM co <*
"-CM CO CO ^J-
~ CM co TJ-
co »~ CM t 10
<- CM CO
~ CM
T- CM CO Tt
T- CM co ^3*
<- CM co ^
>- CM co ^j- to
13 0
03 *-
"D 5
i » i , n i i 1 I i!
I ! 1 ! ! i 1 1 1 !
S iS"? Q «o eo « "D u, , m
* * tti Q) C Q. &D flj r* W V ^3
I 8 1 | ^llfal || If
jo •2'sJ °>S° *=!Dg •>- i yy
O °"§ -oO:=c'w§>-mBc>>-^-3. O)13
f| f | |S || ||Si?ilf I f| 1}
Q. Q.^* oSLJJ^-SPtO* A * C* -5? i 13^
w c 5J
CO :£. CO co -sr (K
co w -Q » $-|
" i W "O SS
11 |I Iff
CD 0 « g g «> S
III 1! Ill
cE-~ mi's
115 ff ill
Sigy * e ^os
-------
wet-wiped with amended water before
seing removed from the abatement area.
Final Visual Inspection
Final visual inspection involves examin-
ing the abatement area for evidence that
the remedial actions have been suc-
cessfully completed, as indicated by the
absence of residue, dust, and debris. The
basic premise of a final visual inspection
is that an area where residue or debris
visible to the unaided eye is still present
is not clean enough for clearance air
sampling.
Final Visual Inspection by AST's
Upon completion of final cleaning, a
final visual inspection was conducted at
each of the 20 abatement sites by an
onsite AST. Two of the 20 sites passed
the first visual inspection, and 18 of the
20 sites required and passed a second
visual inspection.
Final Visual Inspection by
NJDOH's ACS
The New Jersey Department of
Health's Asbestos Control Service (ACS)
conducted final visual inspections at 15 of
the 20 abatement projects. These includ-
ed Sites A through C, H through I and K
hrough T. This inspection is a part of the
State's traditional quality assurance pro-
gram that provides checks and balances
to asbestos abatement to ensure that
high quality abatement and state-of-the-
art work practices are used.
The ACS inspector first visually exam-
ined all substrate surfaces to ensure that
no ACM remained. Special attention was
given to pipes, structural members, ceil-
ing tile grid bars, and irregular surfaces
with corners and hard-to-reach areas. If
any quantity of ACM remained, the site
failed the visual inspection and additional
removal work was performed before an-
other visual inspection was conducted.
The ACS inspector then determined if
the work site had been adequately
cleaned. All surfaces were examined for
dust and debris, especially overhead
areas (such as tops of suspended light
fixtures and ventilation ducts) and areas
under stationary fixtures. One or both of
the following techniques were used for
examining surfaces to establish that a
"no dust" criterion had been achieved:
1. Using a damp cloth to collect dust
from the surface and then inspecting
the cloth for evidence of dust.
2. Darkening the room and shining a
flashlight so that the light beam just
glances across any smooth horizontal
or vertical surface. A gloved finger is
then run across the illuminated area;
if a line is left on the surface, dust is
still present.
If either of these techniques showed
that dust still remained, the ACS inspec-
tor recommended recleaning of the work
area before its reinspection. If debris was
found, the ACS inspector collected bulk
or wipe samples of the debris and sub-
mitted them for analysis by the New
Jersey Department of Health's Public
Health and Environmental Laboratories in
Trenton, New Jersey.
From one to seven visual inspections
were conducted at each of the 15
abatement sites inspected by the ACS.
The largest percentage of sites (33.5%)
passed the visual inspection on the
second attempt. The cumulative per-
centages of sites passing the visual
inspection were as follows: 40% by the
first and second attempts, 66.7% by the
third attempt, and 93.4% by the fourth
attempt.
Fourteen of the 15 sites failed the ACS
inspectors' visual inspection for more
than one reason. The most commonly
identified reason (cited at 8 of the 15
sites) was the presence of debris on
pipes, pipe fittings, and hangers. The
next most common reason was debris on
floors, on horizontal surfaces, and in wall-
penetrations. Twenty-three other less
commonly reported reasons for failing the
visual inspection were also identified.
The ACS inspectors collected 81 bulk
samples to determine the asbestos
content of the debris found during the
visual inspections. Asbestos was present
in approximately 90% (73 of 81) of these
samples.
All 20 abatement sites passed an
onsite AST visual inspection according to
each AST requirement. Fifteen of the 20
sites were subsequently inspected by the
NJDOH's ACS inspectors. Only one site
passed the first ACS visual inspection.
Observation of inspection practices and
procedures showed that the ACS
inspectors conducted a more stringent
and thorough visual inspection.
Aggressive Sampling
Air monitoring for postabatement clear-
ance should be conducted under aggres-
sive sampling conditions. The abatement
area floors, walls, ledges, ceilings, and
other surfaces should be swept with the
exhaust from forced-air equipment (e.g.,
a minimum 1-hp leaf blower) to dislodge
any remaining dust, and stationary fans
should be used to keep fibers suspended
during sampling. Current guidance on
asbestos-abatement work practices and
procedures recommends aggressive
sweeping of the abatement area for a
minimum of 5 min/1000 ft2 of floor area.
The AHERA rule recommends the use of
at least one stationary fan per 10,000 ft3
of workspace to keep the asbestos fibers
suspended during sampling.
Nineteen of the 20 observed abatement
sites used aggressive sampling tech-
niques. Fourteen of these 19 sites failed
to meet the recommended aggressive
air-sweeping rate of at least 5 min/1000
ft2 of floor area.
Only 12 of the 20 sites used stationary
air fans to maintain a constant air
movement during clearance air sampling.
Box-type fans were used at nine of these
sites, and pedestal-type fans were used
at three sites. Fifteen of the observed
sites failed to use the number of fans per
given volume of workspace recom-
mended by AHERA.
Filter Types
Mixed cellulose ester membrane filters
were used in the collection of clearance
air samples at 14 of the 20 observed
abatement sites. Polycarbonate mem-
brane filters were used at six sites.
Although the AHERA rule permits the use
of either filter type, the pore size must be
less than or equal to 0.45 urn for mixed
cellulose ester filters and 0.4 pm for
polycarbonate filters. At three sites, 0.8-
pm pore-size mixed cellulose ester
membrane filters were used to collect
clearance air samples, which did not
comply with the AHERA regulations. All
filters used for clearance air monitoring
were 25 mm in diameter and were
contained in three-piece cassettes with a
50-mm extension cowl.
Filter Rates and Air Volumes
Each filter assembly was attached to
an electric-powered pump operating at a
specified airflow rate. The air samples
were generally collected after a set
length of time so a certain minimum air
volume could be achieved. The AHERA
rule states that pump flow rates between
1 and 10 L/min may be used for 25-mm-
diameter filters. This was practiced at 18
of the 20 sites observed. Only at two
sites were air samples collected at flow
rates greater than 10 L/min. Air volumes
ranged from 1320 to 4161 L for the post-
abatement air samples collected inside
and outside the abatement area at the
observed sites. The AHERA rule recom-
mends sampling between 1200 and 1800
L of air for 25-mm-diameter filters.
-------
Clearance Tests
At 18 of the 20 observed sites, the
laboratory reports indicated that final
clearance air samples were analyzed by
TEM in accordance with either the man-
datory or nonmandatory TEM methods
described in AHERA. At two sites, phase
contrast microscopy was used to analyze
the clearance air samples. Although the
samples were reportedly analyzed in
accordance with NIOSH Method 7400 at
these two sites, the clearance samples
were collected using improper filters, i.e.,
collected using 0.4-jim-pore-size mixed-
cellulose ester filters instead of 0.8-nm-
pore-size mixed-cellulose ester filters
specified in the NIOSH Method.
Eighteen of the 20 sites were cleared
by the AHERA TEM tests. One to three
TEM clearance attempts were made per
abatement site. Approximately 83.3% of
the sites passed on the first attempt after
passing a thorough visual inspection.
All of the 18 sites ultimately passed the
AHERA TEM clearance criterion of the
initial prescreening test (i.e., the average
asbestos concentration of the samples
collected inside the abatement area was
less than or equal to 70 structures/mm2).
Three of the 18 sites initially failed the
prescreening test, and 2 of these sites
subsequently tried to use the Z-Test to
pass clearance. In each case, the site
also failed the Z-Test and had to be
recleaned. The Z-Test was used only
twice at the 20 sites observed in this
study, and it was never used to clear the
abatement site.
Three of the 20 sites were inspected
by only the AST and subsequently
cleared by TEM. Two of these three sites
failed the first TEM clearance attempt
after passing the AST visual inspection.
One site required additional cleaning and
passed TEM clearance on the second
attempt. One site required three TEM
clearance attempts after additional visual
inspections by the AST before it was
cleared. Polycarbonate filters were used
to collect air samples at this site. Back-
ground asbestos contamination in the
field blanks showed an average asbestos
concentration of 53 structures/mm2 on
the first clearance attempt and 105
structures/mm2 in the second attempt.
The field blanks were not analyzed on the
third clearance attempt. Of the 15 sites
that passed the NJDOH visual inspection,
14 subsequently passed TEM clearance
on the first attempt.
After having passed a thorough visual
inspection by the ACS, the largest per-
centage (83.3%) of the sites passing the
ACS visual inspection passed the AHERA
TEM clearance on the first attempt. Only
6.7% (one site) failed the AHERA TEM
clearance after passing a thorough visual
inspection. These data support the prem-
ise that effective final cleaning practices
that meet the standards of a thorough
visual inspection strongly influence
whether the AHERA clearance test or
other TEM clearance tests will be
passed.
One site involved the removing of less
than 3000 ft2 of ACM. For smaller
projects such as this, AHERA permits the
use of phase contrast microscopy to
analyze the clearance samples. Five
samples must be collected inside the
abatement area and each must have a
fiber concentration of less than or equal
to 0.01 fiber/cm3 of air to pass the
clearance criterion. Only one sample was
collected at this site, and its fiber con-
centration was less than 0.01 fiber/cm3.
Site clearance was based on this one air
sample, which is not in accordance with
the five samples required by AHERA.
One other site was cleared by phase
contrast microscopy analysis. According
to AHERA regulations, however, clear-
ance of this site required the use of the
TEM clearance criterion. At this site, only
two samples were collected inside the
abatement area, and the fiber concentra-
tion associated with each was less than
0.01 fiber/cms. Site clearance was based
on these two samples, whereas the PCM
AHERA clearance criteria require a mini-
mum of five samples inside the abate-
ment area.
Conclusions
The following are the principal con-
clusions reached during this study:
1. Final cleaning practices tend to be
similar among abatement contractors.
The sequence of cleaning activities
depends on the surface from which
the asbestos was removed and the
physical structure of the work site.
Meticulous attention to detail in clean-
ing practices is important to a suc-
cessful final cleaning.
2. HEPA-filtration units used under nor-
mal operating conditions at asbestos
abatement sites tend to perform
below the manufacturer's nominal air-
flow. The average operating airflow
ranged from 50% to 80% of the rated
nominal airflow for 93 units
representing 7 model types.
3. Sites passing a stringent, "no-dust"
criterion of a thorough visual inspec-
tion are more likely to pass the
AHERA TEM clearance test. Thirty-
three percent of the sites that passed
only the Asbestos Safety Techni
(AST) visual inspection, and were
subsequently inspected by the I
Jersey Department of Health, pas
AHERA TEM clearance on the
attempt. Ninety-three percent of
sites that passed a more thoro
visual inspection by the NJD
passed AHERA TEM clearance
the first attempt.
4. The initial AHERA Clearance Sere
ing Test, requiring an average ast
tos concentration below 70 str
tures/mm2, is achievable in m;
cases, thereby eliminating the n<
to employ the AHERA Z-test. All
sites cleared by TEM passed the p
screening AHERA TEM clearar
criterion of 70 structures/mm2.
5. AHERA sampling and analytical
quirements and recommendations
not completely understood and 1
lowed by consultants conduct!
clearance air monitoring. The folk
ing clearance air sampling and ai
lytical techniques were observed:
• Fewer than the required fi
clearance air samples inside 1
abatement area were collected
two sites.
• Improper sampling media we
used to collect clearance ;
samples, i.e., filter pore size
three sites and filter type at t\
sites cleared by PCM.
• Eight of the 20 abatement sit
failed to meet the EPA-recor
mended drying time of 24 hou
after final cleaning was complete
before final clearance air monitc
ing was conducted.
• Recommended air sampling flc
rates were exceeded at two sites
• Phase contrast microscopy w;
improperly used to clear one site
• Nineteen of the 20 abatemei
sites used aggressive air san
pling techniques. Fourteen <
these 19 sites failed to meet th
EPA-recommended aggressive a
sweeping rate of at least
min/1000 ft2 of floor area.
• Fifteen of the 20 abatement site
failed to use the number of circi
fating fans recommended b
AHERA during final clearance a
monitoring. No circulating fan
were used at eight of the sites.
Recommendations
Based on the conclusions outline<
above, it is recommended that guidanci
documents be developed which addres:
the following topics:
-------
1. Procedures for visual inspections.
This study suggests that work sites
passing a stringent visual inspection
are less likely to fail the clearance
test and incur the expense of multiple
rounds of sampling and analysis.
Guidance for performing a thorough
visual inspection would benefit both
the building owner and abatement
contractor.
2. Procedures and protocols of AH ERA
air monitoring. Improper final clear-
ance air monitoring resulted partly
from a lack of understanding of
AHERA air monitoring procedures.
The contractors expressed concern
that the EPA-recommended protocols
were in different documents, making
it difficult to completely understand
the current protocols. The AST
recommended that a guidance
document be prepared that contained
the procedures and protocols for
proper AHERA clearance air mon-
itoring.
Operation of HERA filtration units.
No specific guidance has been is-
sued regarding the fundamental oper-
ating principles of these units (e.g.,
decreased airflow performance with
increased static pressure due to filter
loading and the addition of manifolds,
flexible ductwork, etc.). Guidance for
maximizing the operating airflow
performance of air-filtration units used
at asbestos abatement sites is
needed.
The full report was submitted in ful-
fillment of Contract No. 68-03-4006 by
PEI Associates, Inc., under the sponsor-
ship of the U.S. Environmental Protection
Agency.
-------
John R. Kominsky and Ronald W. Freyberg are with PEI Associates, Inc.,
Cincinnati, OH 45246; James A. Brownlee, James H. Lucas, Jr., and Donald R.
Gerber are with New Jersey Department of Health, Trenton, NJ 08625.
Thomas J. Powers is the EPA Project Officer (see below).
The complete report, entitled "Observational Study of Final Cleaning and AH ERA
Clearance Sampling," (Order No. PS 89-233 4491 AS; Cost: $28.95, subject to
change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Risk Reduction Engineering Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
SE S300
Official Business
Penalty for Private Use $300
EPA/600/S2-89/047
0.35
000085833 PS
------- |