United States
Environmental Protection
Agency
Municipal Environmental Research
Laboratory
Cincinnati OH 45268
Research and Development
EPA-600/S2-84-014 Mar. 1984
&ERA Project Summary
Control of Asbestos Fiber Loss
from Asbestos-Cement
Watermain
After the Weston, Wisconsin, Water
Utility discovered the deterioration of a
portion of its asbestos-cement water-
main, research to identify and effective
means of eliminating or reducing the
release of asbestos fibers into its
potable water was begun. Three tech-
niques were investigated: (a) using zinc
chloride to form a protective metallic
precipitate layer on the pipe surface, (b)
in situ cement-mortar lining of the pipe,
and (c) flushing of watermains. Imple-
mentation of the above three asbestos
control processes would have widely
differing capital and operational costs.
The introduction of zinc into system
water did not result in the expected
formation of a protective layer onto
pipe coupons, possibly because of
interference from polyphosphates added
to the system water to sequester iron
and manganese. Cement-mortar lining
of pipe appears to be a useful technique
for rehabilitating still structurally sound
pipe. Temporary elevation of values for
pH as well as calcium and alkalinity
concentrations can, however, be ex-
pected. Flushing does not appear to be
an effective technique for reducing the
concentrations of the fibers because
concentration of asbestos fibers may
become elevated during such high draw
conditions. Of the three techniques
studied at Weston, in situ cement
mortar lining was the most promising
approach for long term control of
release of asbestos fibers from deterio-
rating ^asbestos cement watermains.
This Project Summary was developed
by EPA's Municipal Environmental
Research 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
In 1980, when a Water Utility crew was
installing a tee in a 6-in. asbestos-cement
watermain, they noted that the interior of
a removed asbestos-cement pipe was very
deteriorated and that the inner wall of the
pipe was no longer as smooth as that of a
new pipe. Because of concern for the
condition of the pipe, ways to rehabilitate
or protect asbestos-cement pipe and to
remove accumulated debris from the
mains were studied.
This research project evaluated three
procedures for eliminating or minimizing
the number of asbestos fibers being
released from the watermains into the
water system. The first method was to
introduce a protective zinc coating on the
pipe wall by adding zinc chloride solution
into the water supply. This procedure to
prevent the release of asbestos fibers
would have a low initial capital outlay but
would require perpetual annual operating
costs associated with the necessary
chemicals.
A second potential solution involved
cement-mortar lining of the deteriorated
pipe. Although this method would require
a large capital cost, no additional
operating and maintenance costs would
be required.
Finally, watermain flushing was con-
sidered as a no-cost method of potential
fiber reduction, because flushing is a
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regular operation and maintenance
activity.
Zinc Precipitation Treatment
This test was designed to evaluate the
effectiveness of a precipitated zinc pipe
coating in preventing the release of
asbestos fibers from both new and
deteriorated asbestos-cement pipe. This
test subjected sample pipe coupons to the
utility's water supply treated with 1 mg/L
ZnCI2 without any adjustment of the pH of
the water and to 2 mg/L ZnCI with pH
adjustment to 8.5. Pipe sample coupons
subject to existing utility water conditions
were also included in this test as a
control.
A PVC pipe header was constructed
within a lift station located adjacent to
Fox Street. Three individual lines were
constructed; each contained a ball valve
and pressure gage for flow control and a
3/4-in. water meter with totalizer and
rate of flow indicator. During the test,
flows averaged from 3.73 to 3.84 gpm. A
PVC coupon holder, constructed of 2-1/2-
in. diameter by 6-in. long pipe, was
located downstream from each water
meter. Each coupon holder was capable
of containing two 3-in. by 1-3/4-in. pipe
coupons held end to end. The water ca me
directly from the distribution system,
which in turn was supplied solely from the
Mesker well.
Pipe coupons were prepared from both
new and deteriorated asbestos-cement
pipe. The pipe coupons were weighed,
without any special drying considerations,
and then placed in the coupon holders.
After the coupon test header received a
continuous flow of water for 6 mo, the
coupons were removed and weighed.
Again no particular attention was given to
the moisture content of these coupons.
When it was realized that the moisture
content of the coupons may significantly
affect the conclusions, the coupons were
shipped to the EPA research laboratory in
Cincinnati for drying and weighing. The
relative hardness of each of the pipe
samples was also determined by EPA
(Table 1).
Table 1. Coupon Test of Zinc Treatment
Results of hardness testing do not
show any benefits from the use of a zinc
additive at Weston. This is in contrast to
other experiments where adding zinc
helped protect asbestos-cement pipe.
The lack of positive results for both
sample thickness measurement and
hardness testing would indicate that zinc
did not precipitate onto the pipe sample
coupons to form a protective metallic
layer. This may have been caused by the
zinc's being sequestered by polyphos-
phates that were added to the water to
sequester divalent iron and manganese.
Further research may be needed to
investigate the relationship between zinc
and polyphosphates.
Coupon weight gain was inappropriate
for estimating zinc precipitation on
asbestos-cement pipe. Although this
parameter may be acceptable for metallic
or plastic pipe materials, an alternative
method of evaluating asbestos-cement
pipe coupons is necessary because this
pipe material is porous and subject to
chemical and physical reactions with
water. For future asbestos-cement pipe
research, establishing coupon "dry"
weight may be necessary. Because
obtaining reproducible dry weights with
this porous material is difficult, and
arbitrary "dry weight" standard should
be established. Coupon weights were
within 1% of the 97-day dry weight after
the initial 5- to 7-day drying period, so a 5-
to 7-day drying period should be used as
such a standard.
Pipe Scraping, Polly Pigging,
and Cement Mortar Lining
The length of the 6-in. asbestos-
cement watermain on which the deterior-
ation was initially discovered was sub-
divided into three tests sections labeled A
(308 ft), B (439 ft), and C (427 ft) (Figure
1). Two-inch schedule 40 PVC pipe was
constructed parallel to lines A and C to
allow recirculation of water through these
two sections. Sampling points were
established at the one-third and two-
Recirculating Pump
Measurements
Avg flow, gpm
Avg zinc added, mg/L
Initial wt, gr
Wet wt after test, gr
Dry wt (5 days drying)
gr
Dry wt (97 days drying)
gr
Relative hardness.
Rockwell "L" scale
Pipe D
New Old
3.84
None
96.99
66.84
57.23
56.71
79
94.30
98.24
79.78
78.88
7
PipeE
New Old
88.82
82.45
71.12
70.38
78
3.73
1.4
97.83
90.31
72.92
72.21
-6
Pipe F
New
3.74
2.8
93.63
90.55
78.13
77.24
81
Old
77.46
89.51
72.48
71.73
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Recirculation Pump
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Line
S. T.H. "29"
figure 1. Schematic diagram of Fox Street
watermain test sections A, B, 1
and C. *
thirds points along the length of each
watermain test section.
After these sections were isolated from
the distribution system and water cus-
tomers were provided water from other
mains, the maintenance and rehabilitation
work began. Pipe scraping and cement-
mortar lining work was done under
direction of personnel from Centriline
Division, Raymond International, Inc.
Polly pigging work was directed by
personnel from Becher-Hoppe Service
Corporation. Pipe samples (controls)
were taken before any work was done
and more samples were taken after
various stages of the work. At various
times, the test sections were (1) flushed
with 700 gal of well water delivered by
tank truck to avoid contamination by
asbestos fibers from the distribution
system, (2) drained, and (3) filled with
well water, which was recirculated in the
lines for various times. The recirculated
water was sampled and analyzed for
asbestos fibers.
Test Section A was cleaned with a
single pass of a rubber disc scraper and a
pipe sample was taken. The line was then
cleaned with a cable-pulled metal ^
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scraper, and another pipe sample was
taken. The line was flushed, drained, and
filled with test water. The recirculation
volume before sampling was about
60,000 gal.
Test Section B, which did not have a
recirculation line and pump, was scraped
with a metal scraper and plugged. No
further work was done. Line C was
flushed, drained, and filled with water for
recirculations three times after a series of
passes with different types of Polly Pigs.*
Water samples were taken after each
series of passes; the recirculation volume
before the last sampling was 173,700
gal. Line C was then drained and plugged
temporarily. Later it was lined with
cement mortar.
The effects of pipe maintenance and
rehabilitation were evaluated in three
ways: asbestos cement pipe thickness
was measured and the recirculation
water was analyzed for water chemistry
changes and for asbestos fiber content.
Thickness of the pipe wall exceeded the
minimum wall thickness of 19.81 mm for
the Class 200 pipe used by the Town of
Weston. Neither the scraping nor the
pigging substantially reduced the thick-
ness of the pipe wall. Table 2 shows that
considerable variation in pipe wall
thickness was observed. A scanning
electron microscope showed that calcium
leaching had occurred at the inner pipe
wall. Aggressive water had caused
'Mention of trade names or commercial products
does not constitute endorsement or recommendation
for use.
calcium concentration in the cement
matrix of the asbestos-cement pipe to
decrease in depths of 2.1 to 6.5 mm into
the pipe, as measured from the inner pipe
wall-water interface (Table 2). Hardness
of the pipe specimens, both before and
after scraping or pigging, was less than
hardness of new pipe.
Water quality parameters including pH,
alkalinity, and calcium concentrations
were considerably elevated upon comple-
tion of recirculation test runs conducted
after the cement-mortar lining. These
elevated values are believed to have
resulted from the curing of the cement-
mortar material because these parameters
had shown a definite decreasing trend
with successive recirculation tests runs.
This sort of result would not be expected
for more than a few days or weeks in
water distribution systems when flow is
through and out of cement-mortar lined
mains. No flushing action occurred
during periods of recirculation tests, and
this exaggerated the observed increases.
When the mains wereflushed, drained,
and filled with well water, which was
then recirculated, water samples were
withdrawn for analysis. The asbestos
fiber counts (Table 3) after use of the steel
scraper and Polly Pigs are high when
compared with fiber counts in the well
water a nd the water reci rcu lated after the
cement-mortar lining was applied. The
amphibole asbestos fibers found in the
background water sample came from the
tank truck used to haul the well water.
The lack of any high values (greater
than 10 million fibers per liter (MFL)) of
chrysotile asbestos fibers found after the
cement-mortar lining indicates that this
process is effective in preventing the
release of these fibers from the deterio-
rating pipe. This is consistent with the
96% to 99% reduction of tetrachloroethy-
lene that resulted from placing a cement-
mortar lining over vinyl-lined asbestos
cement pipes in a Massachusetts test.
System Flushing
A flushing test was done in December
1981 on a 1400-ft section of 8-in.
asbestos-cement main (installed in
1970) on Kirk Street. This portion of the
watermain was isolated from the remain-
der of the system by closing valves as
illustrated in Figure 2. During the test,
water samples were taken through the
exterior hose bib at two houses on the
street.
This flushing test was conducted in two
distinct segments. Flow Test One con-
sisted of flushing the water in a northerly
direction along the Kirk Street watermain
and exiting the system at test flow
Hydrant One. Water for Test One was
supplied from the nearby well and the
250,000 gal elevated tower. In Flow Test
Two, a high velocity flow occurred in the
reverse (southerly) direction with water
supplied from the distribution system to
the west. During each test, a rate of flow
and velocity were calculated from mea-
surements of the staticand flowing water
Table 2. Analysis of Pipe Samples Taken During Cement-Mortar Lining Evaluation
Process
Step
Background
Test line A
Control
Rubber disk scraper
Metal scraper
Test line B
Control
Metal scraper
Test line C
Control
Polyurethane pig
Red criss-cross pig
Silicon carbide pig
Wire scraper pig
Pipe Sample
New Pipe
1/3 pt. sample
2/3 pt. sample
1/3 pt. sample
2/3 pt. sample
1/3 pt. sample
2/3 pt. sample
1/3 pt. sample
2/3 pt. sample
1/3 pt. sample
2/3 pt. sample
1/3 pt. sample
2/3 pt. sample
Sample
Thickness
(mm)
21.97
21.20
21.39
20.77
21.30
20.74
21.02
21.34
21.79
21.34
22.73
21.65
25.57
22.28
22.90
20.45
Calcium*
Loss
(mm)
0.0
2.1
2.2
2.5
2.2
2.2
6.5
2.2
2.2
4.1
4.1
4.4
6.5
4.4
3.5
3.0
Mean
Ca/Si
0.83
0.57
0.80
0.6O
0.35
0.6O
0.73
0.64
0.40
0.50
0.49
0.47
0.68
0.84
0.68
0.53
Relative^
Hardness
72
2
-3
16
-11
-32
-6
-5
-8
-24
-20
-13
-15
-12
-13
-12
*'Distance measured from the interior pipe surface.
jModified Rockwell "L" hardness scale.
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Table3.
Water Sample Asbestos Fiber Concentrations Taken During Cement-Mortar Lining
Evaluation
Line
A
A
C
C
C
C
C
C
C
Process
Step
Background
After steel scraper
After first red criss cross pig
After silicon carbide coated pig
After wire pig and second red
criss cross pig
Background^
After cement-mortar lining
After cement-mortar lining
After cement-mortar lining.
Asbestos
Amphibole (MFL)*
0.32
ND
ND
o.ret
0.37t
ND
ND
ND
ND
ND
ND
ND
ND
Fibers
Chrysolite {MFL)
1.6
8.4
87.5
10.9
8.4
49.2
ND
1.71
0.35f
2.1
ND
1.6
1.3
line drained, flushed, and filled
a second time
C
C
Background^
After cement-mortar lining.
line drained, flushed, and
filled a third time
ND
ND
ND
ND
0.131:
0.42\
0.44\
ND
*MFL - Million fibers per liter.
t/Vof statistically significant, less than 5 fibers counted.
^Municipal well water samples from the tank truck.
§Mesker Street well hydrant sample.
Note: Two values are reported where replicate samples were analyzed.
not result in protection of asbestos-
cement pipe.
• Disturbing the inner wall of asbestos-
cement pipe by scraping or by using
Polly Pigs resulted in high asbestos
fiber counts in water that passed
through the treated pipes.
• Lining asbestos-cement pipes with
cement mortar is feasible. Cement
mortar lining can be applied to
asbestos-cement pipes.
• Eliminating or substantially reducing
the asbestos-fiber contamination of
potable water from asbestos-cement
pipes is possible with the cement
linning procedure.
The full report was submitted in
fulfillment of Cooperative Agreement CR-
808476010 by Weston Water Utility,
Schofield, Wl 54476 under the sponsor-
ship of the U.S. Environmental Protection
Agency.
\ • Valves Closed Both Tests
Test 2 Water
Supply
I Closed Test 1
i Open Test 2 \
6102 Kirk St. XT
Sample Point g
Test 1 &2 $>
•£
£
Test 1 Flow Hyd.
AC. Flow
Test Main
6303 Kirk St.
Sample Point Test 2
Open Test 1
Closed Test 2
.J_
250,000 Gal.
EL. Tower
flushing test and the chrysotile asbestos
fiber concentrations are given in Table 4.
The flushing test revealed that chryso-
tile fiber counts were somewhat elevated
when compared with counts for undis-
turbed water, even after 90 min of
flushing. Other studies have indicated
that main flushing results in higher
asbestos fiber counts, possibly by stirring
up asbestos-laden sediment in the mains.
Further testing is needed before recom-
mendations concerning flushing of
asbestos-cement watermains can be
made.
Conclusions
• Using zinc as a corrosion inhibitor in
the presence of polyphosphates may
——" ^—, Table. 4. Flushing Tests and Chrysotile Asbestos Fiber Concentrations
Test 2 Flow Hyd. From Well I
I
Test 1 Water
Supply
2. Schematic diagram of flushing
test on Kirk Street.
Sample
Station
Test No. 1
Background
6102 Kirk Street
6102 Kirk Street
6102 Kirk Street
Test Condition
Flushing, 25 min
Waiting period, additional 85 min
Waiting period, additional 90 min
Chrysotile
Concentration,
MFL*
0. 18 MFL, NSS*
3.22 MFL
9.95 MFL
76. 1 MFL
Figure 2.
pressures recorded at the discharge
hydrant. The flow during Test One was
approximately 1,100 gpm with an ap-
proximate velocity of 7 ft/s. During Test
Two, the flow was calculated to be 820
gpm with an average velocity of 5 ft/s.
The procedures followed during the
Test No. 2 (Valves at Test Hydrant 2 opened and closed (Figure 2)
6102 Kirk Street Sample
6303 Kirk Street
6102 Kirk Street
Waiting period, 15 min
Waiting period, additional 25 min
Hydrants closed and all valves
opened; waiting period, 6 days
No fibers detected
7.32 MFL
0.15 MFL. NS
'Million fibers per liter.
*Not statistically significant
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This Project Summary was prepared'by staffofthe Town of Weston, Schofield. Wl
54476.
Gary S. Logsdon is the EPA Project Officer (see below).
The complete report, entitled "Control of Asbestos Fiber Loss from Asbestos-
Cement Watermain," (Order No. PB 84-148 733; Cost: $10.00. 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:
Municipal Environmental Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
..--^J.3. OFr SCiAL '/'Ali.
' " ~'
("Adie-3--.
Official Business
Penalty for Private Use $300
U.S. GOVERNMENT PRINTING OFFICE: 1984-759-
102/089^
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