EPA/600/R-19/002 | September 2019
www.epa.gov/homeland-security-research
United States
Environmental Protection
Agency
&EPA
Decontamination of	Spores
from Drinking Water Infrastructure
with Physical Removing (pigging)
and Assessment of Pipe
Office of Research and Development
Homeland Security Research Program

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EPA/600/R-19/002
September 2019
Decontamination of Bacillus Spores
from Drinking Water Infrastructure with
Physical Removal (Water Jet Pigging)
and Assessment of Pipe Relining
Technologies
by
Jeffrey Szabo, John Hall and James Goodrich
U.S. Environmental Protection Agency
Cincinnati, OH 45268
Greg Meiners and Sue Witt
Aptim
Cincinnati, OH 45204
Interagency Agreement DW-89-92381801
Office of Research and Development
Homeland Security Research Program
Cincinnati, OH 45268
Contract EP-C-12-014
Office of Research and Development
Homeland Security Research Program
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Disclaimer
The U.S. Environmental Protection Agency (EPA) through its Office of Research and
Development funded and managed the research described herein under contract EP-C-12-014
with Aptim and Interagency Agreement DW-89-92381801 with the Department of Energy. It
has been subjected to the Agency's review and has been approved for publication. Note that
approval does not signify that the contents necessarily reflect the views of the Agency. Any
mention of trade names, products, or services does not imply an endorsement by the U.S.
Government or EPA. The EPA does not endorse any commercial products, services, or
enterprises.
The contractor role did not include establishing Agency policy.
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Table of Contents
Disclaimer	ii
List of Figures	iii
List of Tables	iv
Abbreviations	v
Acknowledgements	vi
Executive Summary	vii
1.0 Introduction	1
1.1	Background	1
1.2	Proj ect Obj ecti ve	1
1.3	WSTB System Description	1
2.0 Description of Pigging and Pipe Relining Techniques	4
2.1	Water Jet Pigging	5
2.2	Pipe relining using spray on coating	10
2.3	CIPP application	12
2.4	Contamination and Decontamination Protocols	14
2.5	Experimental Methods	16
2.6	Quality Control and Data Quality	17
2.6.1	Quality Control	17
2.6.2	Data Quality	18
2.6.3	Deviations	19
3.0 Experimental Results	19
3.1	Water Jet (Warthog) Pigging	19
3.2	Warthog pigging with Oceanit DragX pipe relining	22
3.3	Warthog pigging with CIPP pipe relining	24
3.4	Results Summary Tables	27
4.0 Conclusions	28
5.0 References	31
List of Figures
Figure 1: Schematic overview of Water Security Test Bed (WSTB)	2
Figure 2: Aerial view of the Water Security Test Bed (WSTB)	3
Figure 3: Water Security Test Bed discharge lagoon	3
Figure 4: Individual pipe sections next to the Water Security Test Bed lagoon	4
Figure 5: Warthog nozzle used for pipe scouring	6
Figure 6: Combination (Vactor) truck	7
in

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Figure 7: Water jet nozzle attached to the combination truck high pressure hose	8
Figure 8: Water jet nozzle inserted into a pipe section	9
Figure 9: Spray coming out of a pipe section as the water jet nozzle travels down the pipe	9
Figure 10: Jet sprayer nozzle exiting a pipe section	10
Figure 11: Mixing the Oceanit DragX coating in a bucket	11
Figure 12: Rotary air sprayer inserted into the pipe to apply the DragX coating	11
Figure 13: DragX coated pipe after curing overnight	12
Figure 14: Flexible CIPP sock being cut to the length of the iron pipe	12
Figure 15: Flexible CIPP fabric sock being soaked in resin	13
Figure 16: Resin soaked CIPP sock being pulled through the iron pipe	13
Figure 17: CIPP filled with hot water and in the process of curing	14
Figure 18:Finished CIPP sawed off to the length of the iron pipe	14
Figure 19: Caps inserted on individual pipes during contamination	15
Figure 20: Draining the pipe sections	16
Figure 21: Decontamination of Bacillus globigii (BG) from the cement-mortar lined iron pipe
section with the Warthog nozzle	20
Figure 22: Decontamination of Bacillus globigii (BG) from the corroded iron pipe section with
the Warthog nozzle	20
Figure 23: Decontamination of Bacillus globigii (BG) from the cement-mortar lined iron pipe
section with the Warthog nozzle and Oceanit DragX relining	22
Figure 24: Decontamination of Bacillus globigii (BG) from the corroded iron pipe section with
the Warthog nozzle and Oceanit DragX relining	23
Figure 25: Decontamination of Bacillus globigii (BG) from the cement-mortar lined iron pipe
section with the Warthog nozzle and CIPP relining	25
Figure 26: Decontamination of Bacillus globigii (BG) from the corroded iron pipe section with
the Warthog nozzle and CIPP relining	25
List of Tables
Table 1: Quality Control Data Quality Objectives	18
Table 2: Summary of total BG spore log reduction from each decontamination method tested on
two different pipe types	27
Table 3: Summary of the BG spore log reduction for each step the decontamination processes on
two different pipe types	28
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Abbreviations
atm
atmosphere
BG
Bacillus globigii
BWS
bulk water sample
cfu
colony forming units
CT
chlorine concentration C, (mg/L) x contact time T, (min)
DPD
N,N-di ethyl -p-phenyl enedi amine
ft
foot
gpm
gallons per minute
HPC
heterotrophic plate count
hr
hour
INL
Idaho National Laboratory
LOD
limit of detection
M
meter
min
minute
MPN
most probable number
psi
pounds per square inch
WSTB
Water Security Test Bed
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Acknowledgements
Contributions from the following individuals to the field work described in this report are
acknowledged: Stephen Reese and Travis McLing of the Idaho National Laboratory; Steve
Packer of Big Sky Industrial.
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Executive Summary
The U.S. Environmental Protection Agency's (EPA) Homeland Security Research Program
partnered with the Idaho National Laboratory (INL) to build the Water Security Test Bed
(WSTB) at the INL test site outside of Idaho Falls, Idaho. The WSTB was built using an 8-inch
diameter cement-mortar lined ductile iron drinking water pipe that had been previously taken out
of service. The pipe was exhumed from the INL grounds and oriented in the shape of a small
(450 feet long) drinking water distribution system. The WSTB can support drinking water
distribution system research on a variety of topics including biofilms, water quality, sensors, and
homeland security related contaminants. Since the WSTB is constructed of real drinking water
distribution system pipes, research can be conducted under conditions which are representative
to those in a municipal drinking water system (USEPA, 2016; USEPA, 2018).
This report summarizes the results of biological decontamination experiments performed at the
WSTB. The experiments focused on removing and remediating Bacillus globigii spores adhered
to the inner surface of the 8-inch water pipe. B. globigii spores are a non-pathogenic surrogate
for B. anthracis, which is the causative agent of anthrax. Decontamination was undertaken with
a technique known as pigging, or physical scouring of the inner pipe surface, followed by
disinfection with free chlorine. The pigging decontamination technique used a Warthog® high
pressure water jet nozzle, with the water jet scouring the internal pipe surface. In this technique,
dubbed "Warthog pigging," water was pumped from a combination (Vactor®) truck through the
Warthog nozzle at high flow and pressure (approximately 70 gpm and 2,300 psi, respectively).
The water flow caused the nozzle to spin and discharge a high-pressure water jet that scoured the
inner pipe surface.
After decontamination, two pipe relining technologies were also evaluated in separate
experiments. The first relining technology evaluated was Oceanit DragX™ (Oceanit
Laboratories Inc., Honolulu, HI), which is a proprietary thin (2 mil) spray on polymer coating.
The second relining technology was cured in place pipe (CIPP). This technique works by
inserting a resin saturated cloth tube into the existing iron pipe, filling it with hot water or steam
to cure the resin, then draining the pipe, which leaves a hard, cured pipe inside the original pipe.
Both the pigging and pipe relining techniques were implemented on individual sections of
cement-mortar lined iron pipe and unlined iron pipe with corrosion.
The following is a summary of the results that came from the pigging and relining experiments
performed at the INL WSTB:
•	Warthog pigging (2,300 psi, 70 gpm) of an individual cement-mortar lined iron pipe
section resulted in a 1.9-log reduction of the number of spores detected on the inner pipe
surface. After pigging, chlorination of the water in the pipe at an initial concentration of
149 mg/L (111 mg/L after 18.25 hours) resulted in an additional 1.1-log inactivation of
the spores adhered to the pipe inner surface, for a total reduction of 3.0-log.
•	Warthog pigging (2,300 psi, 70 gpm) of an individual corroded iron pipe section resulted
in a 4.9-log reduction of the number of spores detected on the inner pipe surface. After
pigging, chlorination of the water in the pipe at an initial concentration of 82 mg/L (39
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mg/L after 18.25 hours) resulted in an additional 0.9-log inactivation of the spores
adhered to the pipe inner surface, for a total reduction of 5.8-log.
•	Warthog pigging (2,300 psi, 70 gpm) followed by Oceanit DragX relining of an
individual cement-mortar lined iron pipe section resulted in a 5.4-log reduction of the
number of spores detected on the inner pipe surface (note that spores were only detected
in 2 out of 6 pipe interior samples). After relining, chlorination of the water in the pipe at
an initial concentration of 216 mg/L (133 mg/L after 22.15 hours) resulted in no spores
detected on the interior pipe surface, or up to an additional 0.5-log inactivation of the
spores adhered to the pipe inner surface, for a total reduction of > 5.9-log.
•	Warthog pigging (2,300 psi, 70 gpm) followed by Oceanit DragX relining of an
individual corroded iron pipe section resulted in no spores detected on the inner pipe
surface, or > 6.5-log reduction. After relining, chlorination was still conducted.
Chlorination of the water in the pipe at an initial concentration of 171 mg/L (122 mg/L
after 22 hours) resulted in no detectable spores on the interior pipe surface.
•	Warthog pigging (2,300 psi, 70 gpm) followed by CIPP relining of an individual cement-
mortar lined iron pipe section resulted in a 4.0-log reduction of the number of spores
detected on the inner pipe surface (note that spores were only detected in 2 out of 4 pipe
interior samples after relining). After relining, chlorination of the water in the pipe at an
initial concentration of 215 mg/L (69 mg/L after 16.75 hours) resulted in an additional
0.3-log inactivation of the spores adhered to the pipe inner surface, for a total reduction
of 4.3-log. Spores were detected in 1 out of 4 post chlorination pipe interior samples, and
were likely due to cross contamination.
•	Warthog pigging (2,300 psi, 70 gpm) followed by CIPP relining of an individual
corroded iron pipe section resulted in a 4.5-log reduction of the number of spores
detected on the inner pipe surface (note that spores were only detected in 2 out of 4 pipe
interior samples after relining). After relining, chlorination of the water in the pipe at an
initial concentration of 210 mg/L (59 mg/L after 16.75 hours) resulted in an additional
0.8-log inactivation of the spores adhered to the pipe inner surface, for a total reduction
of 5.3-log. Spores were detected in 1 out of 4 post chlorination pipe interior samples, and
were likely due to cross contamination.
In summary, pigging with the Warthog nozzle followed by chlorination reduced spores on
cement-mortar lined iron by 3.0-log, and by 5.8-log on corroded iron. Increased
decontamination efficacy on corroded iron compared to cement-mortar lined iron was likely due
to the fact that spores were adhered to the corroded iron matrix, which is almost completely
removed during pigging process. After both relining processes were complete, spores were
nearly undetectable. Any detectable spores present after relining (and chlorination) were likely
due to cross contamination of spores from the surrounding area or carry over from the
contaminated pipe. For pipe relining to be successful, cross contamination of contaminant would
need to be controlled.

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It is important to note that these physical scouring and pipe relining activities will require a
longer time frame to implement than standard chlorination and flushing techniques. Excavation
is required to access the pipeline for entry of the water jetting attachment and relining equipment.
Specialty equipment like Vactor trucks are also required for water jetting activities and
significant amounts of contaminated debris will be generated. Consideration should be given to
supplying an alternate source of water to customers while these more extensive remedial efforts
take place. Also, consideration should be given to disposal options for any debris removed by
flushing or drag scraping the pipeline after water jetting. It is possible that significant amounts of
biologically contaminated water and debris could result from water jetting.
Some utilities have successfully relined metal pipes with a thin coating of cement after pipe
cleaning and debris removal. This relining step is necessary to prevent taste and odor complaints
due to the exposure of the iron pipe surface. The results of the pipe rehabilitation have also been
recorded with CCTV video monitoring equipment. Before implementing water jetting as a
decontamination method, decision makers should think about worker safety and contamination
of water and wastewater utility equipment. It is possible that utility equipment will be
contaminated to the extent that it could not be readily used after decontamination is complete.
These additional activities should be considered in practice, but were beyond the scope of this
experiment.
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1.0 Introduction
1.1	Background
The U.S. Environmental Protection Agency's (EPA) Homeland Security Research Program has
partnered with the Idaho National Laboratory (INL) to build the Water Security Test Bed at INL
near Idaho Falls, Idaho. The centerpiece of the Water Security Test Bed (WSTB) is an 8-inch
diameter cement-mortar lined ductile iron drinking water pipe that had been taken out of service.
The pipe was exhumed from the INL grounds and then oriented in the shape of a small drinking
water distribution system. The WSTB has been fitted with service connections, fire hydrants, and
removable coupons (excised sample materials) to collect samples from the pipe interiors
(USEPA, 2016).
Experiments, focused on decontamination of Bacillus globigii spores that adhered to the inner
surface of the 8-inch water pipe, have been conducted at the WSTB in previous years. B.
globigii spores are a non-pathogenic surrogate for B. anthracis, which is the causative agent of
anthrax. The standard protocol that most utilities follow in response to a bacterial contamination
event involves chlorination and flushing and described in AWWA Standard C-651-05:
Disinfecting of Water Mains (AWWA, 2005). Therefore, EPA's initial experiment using the full-
scale WSTB used chlorine dioxide to decontaminate adhered spores. Two-log removal of B.
globigii spores was observed with flushing and chlorine dioxide decontamination, which was
less effective than anticipated based on previous pilot-scale experiments (Szabo et al, 2017a;
Szabo et al, 2017b; USEPA, 2016). Chlorine dioxide is a powerful disinfectant, and it was not
anticipated that other common drinking water disinfectants such as free chlorine or
monochloramine would be more effective. Therefore, subsequent efforts at removing adhered B.
globigii spores were focused on physical removal or scouring of the inner pipe surface, hereafter
referred to as "pigging." Two technologies were selected: ice pigging and chain cutter pigging.
Ice pigging was ineffective at removing spores. Physical scouring using a chain cutter nozzle
followed by chlorination removed approximately 4.0-log spores from the inner pipe surface, but
spores did remain on the inner pipe surface after decontamination (USEPA, 2018). These results
led to further experiments on physical scouring and pipe relining, which are detailed in this
report.
1.2	Project Objective
Previous experiments at the WSTB have shown that the standard chlorination and flushing
methods were less effective than expected for adhered spores, and ice pigging was not an
effective spore decontamination method (Szabo et al, 2017a; USEPA, 2018). The objectives of
this project were to evaluate the effectiveness of: (1) a physical scouring (pigging) technology
for removing B. globigii spores following intentional contamination of the WSTB; (2) two pipe
relining technologies for encapsulating residual spores on the pipe inner surface after pigging;
and (3) chlorination for residual spore destruction after pigging and pipe relining.
1.3	WS TB System Description
The primary feature of the WSTB is an 8-inch (20 cm) diameter cement-mortar lined ductile iron
drinking water pipe oriented in the shape of a small drinking water distribution system. The
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WSTB contains ports for service connections and a 15-foot (5 m) removable coupon section
designed to sample the pipe interior to examine the results from contamination/decontamination
experiments on the pipe wall. Figure 1 schematically depicts the main features of the WSTB.
End of
WSTB
Legend
FM Flow Meter
PG Pressure Gauge
IP1 Instrument Panel 1 (Upstream, Cellular)
IP2 Instrument Panel 2 (Downstream, Radio)
XI Valve, Open
Valve, Closed
|>^ Valve, Partly Open
^ Fire Hydrant
Flushing Hydrant
Blind Flange
Pressure Reducing Valve
Check Valve
—> Service Connector (Closed)
-3
Not to Scale
15-ft Coupon Section
—X-
Existing Fire Hydrant
Fire Hose
Start of WSTB f
Injection Port -CXI—
@—1X1—
Parking
Area
Figure 1: Schematic overview of Water Security Test Bed (WSTB).
Figure 2 shows the aerial view of the WSTB. The lower right corner shows the upstream and
system inlet; the upper left corner shows the lagoon.
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Downstream fire hydrant
WSTB end
WSTB start
Upstream fire hydrant and injection port
Figure 2: Aerial view of the Water Security Test Bed (WSTB).
Drinking water supplied to the WSTB is chlorinated ground water that also supplied the
surrounding INL facilities. The WSTB incorporates approximately 450 feet (137 m) of 8-inch
(20 cm) diameter cement-mortar lined ductile iron pipe. The 8-inch (20 cm) pipe system is
constructed directly over the lined drainage ditch for spill/ leak containment (as shown in Figure
2). The total volume of the WSTB was estimated to be around 1,150 gallons (4,353 L). The
effluent water from the WSTB system was discharged to a lined lagoon (Figure 3) which has a
total water storage capacity of 28,000 gallons (105,980 L).
North
Figure 3: Water Security Test Bed discharge lagoon.
To examine pigging and pipe relining technologies, individual sections of pipe were set up next
to the lagoon. The individual pipe setup is shown in Figure 4. Two types of pipe were pigged
and relined. One was the same cement-mortar lined iron pipe used in the 450 ft WSTB pipe
(each pipe was approximately 18 ft). The other was iron pipe with heavy corrosion on the
interior (each pipe was approximately 10 ft). This pipe was obtained from the District of
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Columbia Water and Sewer Authority (DC Water). All pipe surface samples taken from the
individual pipes were direct scrapings of the inner surface. Further details on the contamination,
pigging, pipe relining, and sampling processes are described in Section 2.
Cement-mortar lined
iron pipe
Figure 4: Individual pipe sections next to the Water Security Test Bed lagoon.
2.0 Description of Pigging and Pipe Relining Techniques
Historically, the term "pigging," in the context of pipeline cleanup operations, refers to the
practice of using mechanical devices known as "pigs" to perform cleanup activities. The original
mechanical pigs used for cleaning pipes were made from straw wrapped in wire. This device
would make a squealing noise when scraping the pipe walls and traveling through the pipe,
which led to the process being called pigging. In general, pipeline cleaning operations using pigs
are accomplished by launching the pig at an upstream location and pushing the pig down the pipe
until it reaches a downstream receiving station for retrieval.
In industrial applications, soft foam pigs are most commonly used for pipe cleaning applications.
The soft pigs are constaicted using flexible open cell polyurethane foam materials (or other
materials with similar properties) topped with select external wrapping that is suited for
individual application. The soft pigs are slightly oversized and designed to form a "sliding seal"
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in the pipe. When pushed through the pipe, the soft pig can mechanically scrape and remove
product buildup, foreign matter and loose sediment from the pipe walls. In general, soft pigs are
not appropriate for drinking water pipes due to the interior roughness of those pipes.
Physical scouring of drinking water pipe interiors can be performed using a variety of nozzles or
metal tips that are attached to a high-pressure hose. These pigs are activated by pumping water
at high pressure and flow through the nozzles. Pigs of this type have been used for at least 35
years (Beck et al, 1983). Past pigging research at the WSTB used a chain cutter nozzle, where a
spinning chain scours the pipe interior (USEPA, 2018). In this study, a nozzle was used that
produces a high-pressure water jet (or spray) that hits the pipe interior at an angle.
It was not practical to implement different relining methods within the long 440 ft WSTB
pipeline, so three separate smaller lengths of piping were set up at the test bed to evaluate pipe
relining. There are many different pipe relining materials and methods. For the purposes of this
study two representative pipe relining technologies were also implemented in the three separate
sections of pipe. One method was cured in place pipe (CIPP), which is a common pipe
rehabilitation method where a new pipe is inserted into an old pipe and cured in place, usually
through heat treatment. A CIPP material by Permaliner was used for this relining experiment.
The new pipe then becomes the inner surface of the old pipe, and can provide structural integrity,
if needed. A second relining method (Oceanit DragX®; Oceanit Laboratories Inc., Honolulu,
HI) was a spray on coating, where a new non-structural lining is sprayed onto the inner surface
of the pipe. DragX is a proprietary nanocomposite technology that creates a durable, low-
friction internal pipe surface. After coating, the new surface is approximately 2 mil (0.002
inches or 0.051 mm).
There are advantages and disadvantages to both pipe relining methods. The CIPP method adds
structural strength and integrity to the pipe after curing that cannot be provided by the spray-on
liner. However, each individual service connection to the CIPP must be re-cut after the liner
cures. This additional step is not required for the spray on liner method. A detailed description of
each lining process is provided in the following sections.
2.1 Water Jet Pigging
The nozzle shown in Figure 5 is the Warthog WHR Switcher (Stone Age Tools, Durango, CO),
and was used to scour the internal surface of the pipe. INL contracted Big Sky Industrial (Big
Sky, Spokane, WA) to perform the pipe scouring work at the Water Security Test Bed. This
nozzle is capable of being inserted into pipes from 6 to 18 inches in diameter and was designed
to remove obstructions and blockages in pipes such as roots, debris and tuberculation (like iron
corrosion). This type of pig is primarily used to clear wastewater piping clogged with persistent
tree roots, however the field operation of the device was the same for drinking water pipe
decontamination. When water flows into the rear end of the nozzle (at the left of Figure 5), the
front end (right end of Figure 5) rotates, and water flows out in a high pressure jet through
multiple openings at the head of the nozzle. After hitting the inner pipe surface, the high-
pressure jets flow toward the rear end of the nozzle and helps propel the nozzle forward.
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Water
jets
Pressurized water entry
Figure 5: Warthog nozzle used for pipe scouring
(reproduced from https://stoneagetools.com/whr-switcher)
To achieve the appropriate amount of scouring action, water was supplied from a combination
truck, which is shown in Figure 6. Big Sky provided the Vactor® truck and the operator for this
pigging experiment. In the wastewater industry, combination trucks are commonly referred to as
"Vactor trucks" after one of the manufacturers of these vehicles. Combination trucks have a dual
function. The hose on the front can vacuum solids out of a sewer and pump them into the tank
on the back. The truck can also store approximately 1,300 gallons (4,921 L) of potable water
and pump it through a high pressure hose at up to 2500 psi (170 atm) and 80 gpm (302 L/min).
Water at a flow of 70 gpm (265 L/min) and 2300 psi (157 atm) pressure was used to operate the
Warthog nozzle inside of the pipe sections next to the WSTB lagoon. Figure 7 shows the
Warthog nozzle installed at the end of the high pressure hose. The Warthog attachment was
moved at approximately 1 ft /second during the jetting of the 440 foot long pipe. Two passes
were made within the 440 foot pipe.
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Sewer vacuum and storage tank
650 gal water storage tank
(identical tank on the other side
total capacity 1,300 gallons)
High pressure hose reel
Figure 6: Combination (Vactor) truck.
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Figure 7: Water jet nozzle attached to the combination truck high pressure hose.
Images showing the process of pigging the individual pipe section are shown in Figure 8 through
Figure 10. After the combination truck was filled with water and the nozzle was installed on the
hose, the nozzle was placed inside of an individual pipe section. When the high pressure water
pump on the combination truck was turned on, the water began flowing through the nozzle, and
the nozzle began spinning and spraying water. High pressure water exited through an opening in
the rear of the chain cutter nozzle, and this pressurized water flow propelled the chain cutter
down the pipe. The nozzle was operated at a pressure of 2,300 psi and a flowrate of 70 gpm.
These are approximate values that might have varied during operation of the nozzle. Once
pigging of a pipe was complete, the nozzle was pulled back through the pipe, inserted into
another pipe, and the process repeated. Pigging was performed with one pass through the pipe.
However, if visible corrosion or other adhered material was observed after one pass, a second
pass with the nozzle was performed.
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Figure 8: Water jet nozzle inserted into a pipe section.
Figure 9: Spray coming out of a pipe section as the water jet nozzle travels down the pipe.
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Figure 10: Jet sprayer nozzle exiting a pipe section.
2.2 Pipe reiining using spray on coating
Application of Oceanit DragX coating is illustrated in Figure 11 through Figure 13. The pipe
was pigged with the water jet sprayer prior to coating (see section 2.3 for more detail), but the
Oceanit site personnel scrubbed the pipe interior with a wire brush to remove any remaining
debris. Then, the proprietary nanocomposite coating was mixed in a bucket. A hose was
inserted into the bucket, and the coating was pumped to an air driven spin coater that was pulled
through the pipe. The coating cured overnight and was visually inspected the next morning for
trapped air bubbles or bare spots (none were detected).
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Figure 11: Mixing the Oceanit DragX coating in a bucket.
Figure 12: Rotary air sprayer inserted into the pipe to apply the DragX coating.
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Figure 13: DragX coated pipe after curing overnight.
2.3 CIPP application
The application of CIPP is illustrated in Figure 14 through Figure 18. First, a flexible fabric sock
was unrolled and cut to the length of the pipe. The sock was then soaked in a proprietary resin,
and the resin-soaked sock was pulled through the pipe section. The sock was then tied at one
end, and hot water pumped into the sock so that it fully inflated and was forced against the iron
pipe interior. Over approximately four hours, the hot water cured the liquid resin, which was
transformed into a rigid lining. The CIPP was then drained and sawed off at the ends so that the
new interior pipe was flushed with the iron pipe.
Figure 14: Flexible CIPP sock being cut to the length of the iron pipe.
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Figure 15: Flexible CIPP fabric sock being soaked in resin.
Figure 16: Resin soaked CIPP sock being pulled through the iron pipe.
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Figure 17: CIPP filled with hot water and in the process of curing.
Figure 18: Finished CIPP sawed off to the length of the iron pipe.
2.4 Contamination and Decontamination Protocols
Contamination and decontamination took place as follows:
Step 1 - Pipe conditioning (cultivation of biofilm)
Step 2 - Contamination (addition of B. globigii spores to WSTB pipes)
Step 3 - Decontamination (Pigging, chlorination and pipe relining)
Step 4 - Post pigging and relining disinfection
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Step 1 - Pipe Preparation (cultivation of biofilin)
As shown in Figure 4, individual sections of pipe were used for pigging and relining
experiments. Before contamination, baseline samples were taken for B. g/obigii spores and
heterotrophic plate count (HPC). The pipes were wetted before these samples were taken, but
HPC levels represented what was present on the recently wetted dry pipe.
Step 2 - Contamination (Addition of B. globigii Spores to WSTB pipes)
During contamination, caps were installed on each end of the pipe (Figure 19). The caps had two
influent ports so that local tap water and B. globigii spores could be injected simultaneously (see
arrows on Figure 19). Tap water was introduced through a garden hose, and the spores were
pumped in. The mixing action of simultaneous filling ensured that the spores were mixed evenly
throughout the bulk water phase in the pipe. Enough spores were injected to achieve
approximately 5 x 105 cfu/mL in the pipe bulk water phase. After the pipe sections were filled,
the spores were allowed to contact the pipe surfaces for 1 to 2 hours. The spore suspension was
then drained (Figure 20), and the pipes were filled with local tap water until pigging was
performed. Background water and pipe surface samples were taken before contamination,
immediately after contamination, and then the morning of the day following contamination
(immediately before pigging).
Figure 19: Caps inserted on individual pipes during contamination.
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Figure 20: Draining the pipe sections.
Step 3 - Decontamination (Pigging, chlorination and pipe relining)
Pigging was performed as described in Section 2.1, and pipe relining as in Sections 2.2 and 2.3.
Three pipes of each material (cement-mortar line iron and corroded iron) were used. One pipe of
each material was pigged and chlorinated (see Step 4). The other two pipes of each material were
pigged, relined (one with CIPP, one with DragX), and chlorinated (see Step 4).
Step 4 - Post pigging and relining disinfection
Following the completion of pigging or pipe relining, commercially available bleach (8.25%
sodium hypochlorite) was injected into the pipe sections. Bleach was pumped into and mixed in
the pipe sections in the same manner as the BG spores. In pipes that were pigged only,
chlorination took place after pigging. In pipes that were relined, chlorination took place after
relining. Aliquots of bleach were added to achieve a free chlorine concentration between 70 to
80 mg/L once the bleach mixed throughout the pipe bulk water phase. After overnight contact
(16-20 hours), the pipe was emptied and flushed with clean tap water. Chlorination is a common
method of pipe disinfection in the drinking water industry, which is why it was chosen for
disinfection in this study. However, due to variations in pipe demand and volume of bleach
added, the overnight chlorine concentrations differed from the target of 70 to 80 mg/L in some
experiments. These results are described in the section 3.0.
2.5 Experimental Methods
Preparation and transport of B. si obi si i spores
Bacillus globigii spores were produced by mixing an inoculum of B. globigii spores with generic
sporulation media and incubating with gentle shaking at 35 °C for 7 days. The B. globigii
suspensions were heat-shocked and enumerated using the spread plate method with tryptic soy
agar and membrane filtration (plating is described later in this section). The resulting prepared
stock was shipped in separate 1 liter containers inside coolers (preserved at 4 ± 2 °C) to the site.
16

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This suspension was pumped into the pipe sections during contamination (Section 2.4, Step 2).
Extraction of biofilm and spores from coupon and pipe surfaces for microbial analyses
Pipe surface samples were taken directly from the inner surface of the pipe sections. The
biofilm, corrosion and spores were scraped from the surface using a disposable sterile surgical
scalpel. An O-ring with an area of 0.371 square inches (2.4 square centimeters) was placed on
the pipe wall, and the area inside the O-ring was scraped. This ensured that the same area was
scraped for each sample. The extracted material was collected in a sterile sample bottle with a
sodium thiosulfate tablet (for dechlorination of the water) and 100 mL of pre-filled carbon-
filtered water. The extracted sample was transferred to a cooler at 4 ±2 °C. The samples were
shipped cooled overnight to the EPA laboratory and analyzed upon receipt. After the pipes were
relined, the same method was used to sample the pipe surfaces, except that a sterile cotton swab
on a wooden stick was used. Using a scalpel on the relined surfaces would have scraped off the
relined surface, exposing the spore contaminated surface underneath.
Enumeration of B. globigii and Heterotrophic Plate Count
Upon receipt in the lab, samples containing B. globigii spores were heat-shocked at 80°C for 10
minutes and analyzed using the Standard Methods Spread Plate Method 9215 (APHA, 2005).
Tryptic soy agar plates were used for B. globigii spores. B. globigii plates were incubated at 35°
to 37°C for 24 hours. Heterotrophic plate count samples were analyzed using the IDEXX
SimPlate® method (Westbrook, ME) according to Standard Methods 9215E (APHA, 2005).
Plates were incubated at 35° ± 0.5° C for 45 to 72 hours. When needed, samples were serially
diluted (B. globigii and HPC) or membrane filtered (B. globigii).
Bulk water samples
The BWS for B. globigii were collected using the grab sampling technique in 100 mL sterile
sample bottles with a sodium thiosulfate tablet. The bulk water sampling port in the WSTB
coupon section was opened and the water was drained for 15 seconds prior to collection of 100
ml of water from the WSTB.
Free Chlorine
During decontamination experiments, 100 ml grab samples were collected from the pipe
sections. The water was drained for 15 seconds prior to collection of 100 ml of water from the
WSTB. Samples were collected in a clean glass laboratory beaker and analyzed for free chlorine
using a portable Hach® colorimeter Hach, Loveland, CO). The sample was immediately
processed for free chlorine using the Hach Method 10102 using N,N-diethyl-p-
phenylenediamine (DPD) at the WSTB site. Samples were diluted in distilled water as needed.
2.6 Quality Control and Data Quality
2.6.1 Quality Control
Quality control samples for the contaminant reference method included continuing duplicate
samples, controls and laboratory blanks. The data quality objectives for each of these quality
control samples are provided in Table 1. The acceptable ranges limit the error introduced into
17

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the experimental work. All analytical methods operated within the QC requirements for controls
and laboratory blanks in Table 1. Note that duplicate samples for B. globigii refer to a duplicate
analysis of one sample. All B. globigii, HPC and free chlorine samples were collected in
duplicate.
Table 1: Quality Control Data Quality Objectives
Measurement
QC Check
Frequency
Acceptance
Criteria
Corrective Action
B. globigii
Positive control
using stock
Once per
experiment
±10 fold of the
spiking suspension
Investigate laboratory
technique. Change
stock organisms and
use new set of media
plates. Re-analyze the
spiking suspension and
change it if necessary.
B. globigii
Negative Control
using sterile buffer
Once per
experiment
0 CFU/plate
Investigate laboratory
technique. Use a new
lot. Re-analyze.
B. globigii
Negative control
for heat shock
Once per
experiment
0 CFU of
vegetative
cell/plate
Investigate the hot
water bath. Heat
samples for longer
period.
B. globigii
Duplicate
Once per
experiment
<20% variation
Consider other
dilutions. Reanalyze.
B. globigii
Field blank (an
open bottle of
sterile water in the
vicinity of the
BWS location)
Every 5 BWS
0 CFU/plate
Determine if
background values
impact results.
HPC
Negative Control
Before every set
of measurements
No fluorescent
wells
Re-analyze sterile
buffer and change it if
necessary.
HPC
Positive Control
Once per
experiment
Fluorescent wells
Investigate laboratory
technique. Re-analyze.
HPC
Duplicate
Once per
experiment
Duplicate plates
much agree within
5%
Investigate laboratory
technique. Re-analyze.
Free Chlorine
Manufacturer DPD
color standards kit
Once per
experiment
As specified by the
color standards kit
Clean the colorimeter
measuring cell. Clean
the DPD standards vials
and recheck.
2.6.2 Data Quality
At least 10% of the data acquired during the evaluation were audited. These data include the
biofilm/BG spore measurements and water quality measurements. The data was traced from the
initial acquisition, through analysis, to final reporting, to ensure the integrity of the reported
results. All calculations performed on the data undergoing the audit were checked. No significant
adverse findings were noted in this audit.
18

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2.6.3 Deviations
When conducting scrape samples from the interior of the drinking water, and o-ring was used to
isolate the area to be sampled (see "Extraction of biofilm and spores from coupon and pipe
surfaces for microbial analyses" in Section 2.5). Scraping within the o-ring area was meant to
standardize the pipe surface area that was sampled. The tip of a scalpel was to trace the sampled
area inside the o-ring. It was observed in the field that the traced area was not always an exact
circle. Therefore, the area sampled may have varied between samples. It was not possible to
precisely quantify this variation. However, it was estimated that the sampled area could have
varied by 5% between samples. This should be considered when interpreting the data.
3.0	Experimental Results
3.1	Water Jet (Warthog) Pigging
The background HPC concentration on the cement-mortar lined and corroded iron inner pipe
surfaces were analyzed via two scrape samples. These samples were removed after wetting the
pipes with tap water, but before contamination with spores and decontamination with pigging.
Mean HPC values from the two scrape samples from cement-mortar lined and corroded iron
pipes were 3.9 x 105 most probable number (MPN)/cm2 and 2.4 x 105 MPN/cm2, respectively.
These results indicate that viable biofilm was present on the pipe walls prior to the initiation of
the tests.
The pigging decontamination technique known as "Warthog pigging" uses a Warthog® high
pressure water jet nozzle, with the water jet scouring the internal pipe surface. Water jetting is
more commonly used in sewer cleaning and root and clog removal than drinking water
applications. The Vactor truck hosing and Warthog attachment would be amenable to
disinfection with a strong bleach solution. A dedicated Vactor and warthog may be needed for
drinking water systems if resources allow. Figure 21 and Figure 22 graphically summarizes the
data obtained from the Warthog pigging experiments. The B. globigii spore values obtained from
the pipe wall samples have been converted to colony forming units per square centimeter
(CFU/cm2). For all bars in Figure 21 and Figure 22, the "n" value shown in the legend represents
the number of coupons samples taken during that phase of the experiment. The bar represents
the average of those coupons, and the error bars represent standard deviation. The limit of
detection (LOD) in the figures was calculated as follows: The scrapings from the sampled
surface went into 100 ml of sterile buffer. Then 22.2 ml of the buffer suspension containing the
coupons scrapings were membrane filtered in duplicate three sample volumes (O.lmL, lmL, and
lOmL). If one spore was contained in the filtered 22.2 ml, that scales up to 4.5 per 100 ml. When
that value was normalized by the coupon area 2.4 cm2, this yields a value of 1.9 CFU/cm2. Note
that the same LOD applies to Figures 23 to 26 in Sections 3.2 and 3.3.
19

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Q-	¦ Pre-BG injection Spore Density, n=2
g	¦ Spore Density During BG Injection, n=4	LOD: 1.9 cfu/cm2)
¦	Post-BG Injection, Pre-Pigging Spore Density, n=4
¦	Post Pigging Spore Density, n=6
Post Chlorination Spore Density, n=4
Figure 21: Decontamination of Bacillus globigii (BG) front the cement-mortar lined iron
pipe section with the Warthog nozzle.
^ l.E+07
PM
g	¦ Spore Density During BG Injection, n=4	LOD: 1.9 cfu/cm2)
¦	Post-BG Injection, Pre-Pigging Spore Density, n=4
¦	Post Pigging Spore Density, n=6
Post Chlorination Spore Density, n=4
Figure 22: Decontamination of Bacillus globigii (BG) from the corroded iron pipe section
with the Warthog nozzle.
The first bar (pre-BG injection spore density) in Figure 21 and Figure 22 reflect samples taken
before contamination with spores. In both figures, spores are present. The pipes were not in
contact with spores before contamination. However, previous experiments may have
20

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contaminated the surrounding area with spore forming bacteria. The pipe sat open on the site for
approximately 4 weeks before experiments began. Therefore, it is possible that spore
contaminated dirt or dust blew into the pipes, and spores were not washed off when the pipes
were wetted for HPC sampling.
The second bar (spore density during BG injection) represents the number of viable spores
detected on the pipe surface immediately after spore contamination. The bulk water phase had
6.6 x 105 and 3 .3 xlO5 CFU/mL during contamination in the cement-mortar and corroded iron
pipe, respectively. The pipes were contaminated, drained, sampled, and then filled with tap water
until pigging took place the next day. The third bar (Post-BG injection) represents the number of
viable spores attached to the pipe surface immediately before pigging took place. Any decrease
between the second and third bar represents the number of spores that came off of the pipe
surface or were inactivated between contamination and immediately before pigging. The fourth
bar (Post pigging BG spore density) represents the number of viable B. globigii spores attached
to the pipe surface after pigging. The last bar (Post chlorination spore density) shows the
number of viable spores recovered from pipe surface after chlorination.
Figure 21 shows the Warthog pigging and decontamination results for the cement mortar lined
pipe. Pigging with the Warthog nozzle resulted in 1.9 log removal of spores from the pipe
surface. Chlorination resulted in an additional 1.1 log reduction, for a combined total of 3.0 log
reduction. Figure 22 shows the Warthog pigging and decontamination results for the corroded
iron pipe. Pigging with the Warthog nozzle resulted in 4.9 log removal of spores from the pipe
surface. Chlorination resulted in an additional 0.9 log reduction, for a combined total of >5.8 log
reduction. No viable spores were detected on the corroded iron pipe surface after chlorination.
During the chlorination phase, aliquots of chlorine bleach were added to the pipe sections with
the goal of achieving 70 to 80 mg/L free chlorine. In the cement-mortar pipe, the initial free
chlorine concentration was 149 mg/L. After 18.25 hours of contact, the free chlorine
concentration was 111 mg/L. These values yield a bulk phase CT (chlorine concentration, C, in
mg/L and contact time, T, in minutes) of 183,960 mg-min/L. CT is calculated by plotting
concentration (y-axis) vs time (x-axis) and determining the area under the curve. In the corroded
iron pipe, the initial free chlorine concentration was 82 mg/L. After 18.25 hours of contact, the
free chlorine concentration was 39 mg/L. These values yield a bulk phase CT of 112,850 mg-
min/L. No viable spores were detected in the bulk water phase after the bleach had been flushed
from the pipe and tap water restored.
Comparing the results in Figure 21 and Figure 22 shows that pigging with the Warthog nozzle
was more effective in the corroded iron pipe than the cement-mortar lined pipe. This is likely
due to the fact that the spores adhered to the iron corrosion layer on the surface of the pipe. This
iron corrosion layer was removed during pigging to the extent that only bare iron was visible
after pigging. A similar level of surface removal was not observed in the cement-mortar lined
pipe. Similar results were observed when using a chain cutter nozzle for pigging in previous
experiments (USEPA, 2018). However, when using disinfectants alone, decontamination of
spores adhered to corroded iron was more difficult compared to cement-mortar (Szabo et al,
2017). It should also be noted that spores detected on the pipe surface before contamination
were not detected after pigging and chlorination.
21

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3.2 Warthog pigging with Oceanit DragX pipe reiining
The background HPC concentration on the cement-mortar lined and corroded iron inner pipe
surfaces were analyzed via two scrape samples. These samples were removed after wetting the
pipes with tap water, but before contamination with spores and decontamination with pigging.
Mean HPC values from the two scrape samples from cement-mortar lined (Figure 23) and
corroded iron pipes (Figure 24) were 5.1 x 105 most probable number (MPN)/cm2 and 2.9 x 105
MPN/cm2, respectively. These results indicate that viable biofilm was present on the pipe walls
prior to the initiation of the tests.
l.E+06
l.E+05
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U
3
M—
~ l.E+04
c
o
a.
3
O
u
C
o
>
'tn
C
a)
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„ l.E+07
J, l.E+06
^ l.E+05
C/l
° l.E+04
S l.E+03
c
> l.E+02
£ l.E+01
"O
£ l.E+OO
a.
U
CO
Figure 24: Decontamination of Bacillus globigii (BG) from the corroded iron pipe section
with the Warthog nozzle and Oceanit DragX relining
The first bar (pre-BG injection spore density) in Figure 23 and Figure 24 reflect samples taken
before contamination with spores. In Figure 24, spores are present. The pipe was not in contact
with spores before contamination. However, previous experiments may have contaminated the
surrounding area with spore forming bacteria. The pipe sat open on the site for approximately 4
weeks before experiments began. Therefore, it is possible that spore contaminated dirt or dust
blew into the pipe, and spores were not washed off when the pipes were wetted for HPC
sampling.
The second bar (spore density during BG injection) represents the number of viable spores
detected on the pipe surface immediately after spore contamination. The bulk water phase had
5.3 x 105 and 6 .2 xlO5 CFU/mL during contamination in the cement-mortar and corroded iron
pipe, respectively. The pipes were contaminated, drained, sampled, and then filled with tap water
until pigging took place the next day. The third bar (Post-BG injection) represents the number of
viable spores attached to the pipe surface immediately before pigging took place. Any decrease
between the second and third bar represents the number of spores that came off of the pipe
surface between contamination and immediately before pigging. The fourth bar (Post pigging
BG spore density) represents the number of viable B. globigii spores attached to the pipe surface
after pigging. The fifth bar (Post pipe relining) summarizes the number of viable B. globigii
spores recovered from the inner pipe surface after relining. The last bar (Post chlorination spore
density) represents the number of viable spores recovered from pipe surface after chlorination.
Note that these bars are absent from Figure 24 since no spores were detected on these samples.
Figure 23 shows the Warthog pigging and Oceanit DragX relining results for the cement mortar
lined pipe. Pigging with the Warthog nozzle resulted in 4.0 log removal of spores from the pipe
surface. Relining with DragX reduced the number of viable spores detected by 1.4 log.
Chlorination resulted in an additional 0.5 log reduction, for a combined total of >5.9 log
Post Pigging. Relining and
Chlorination: No spores
detected on any sample
¦	Spore Density During BG Injection, n=4	lqd: 1.9 cfu/cm2)
¦	Post-BG Injection, Pre-Pigging Spore Density, n=4
Post Pigging Spore Density, n=6
¦	Post Pipe Relining, n=6
Post Chlorination Spore Density, n=4
23

-------
reduction. No viable spores were detected on the corroded iron pipe surface after chlorination.
Figure 22 shows the Warthog pigging and Oceanit DragX relining results for the corroded iron
pipe. Pigging with the Warthog nozzle resulted in > 6.5 log removal of spores from the pipe
surface. No spores were detected on the lined pipe surface after relining or chlorination.
During the chlorination phase, aliquots of chlorine bleach were added to the pipe sections with
the goal of achieving 70 to 80 mg/L free chlorine. In the relined cement-mortar pipe, the initial
free chlorine concentration was 216 mg/L. After 22.15 hours of contact, the free chlorine
concentration was 133 mg/L. These values yield a bulk phase CT of 281,141 mg-min/L. In the
corroded iron pipe, the initial free chlorine concentration was 171 mg/L. After 22 hours of
contact, the free chlorine concentration was 122 mg/L. These values yield a bulk phase CT of
214,073 mg-min/L. No viable spores were detected in the bulk water phase after the bleach had
been flushed from the pipe and tap water restored.
The results in Figure 23 and Figure 24 show that after pigging, relining with Oceanit DragX and
chlorination, no spores were detected on the inner pipe surface. However, the degree to which
each decontamination process affected the adhered spores differed between the two pipe
materials. Before lining with DragX, pigging with the Warthog nozzle resulted in 4.0 log
removal of the spores (Figure 23). However, in Figure 21, only 1.9 log spore removal was
observed in the cement-mortar lined pipe that was pigged in the same manner. This shows that
pigging effectiveness can differ between two pipes of the same material.
After relining with DragX, spores were only detected in two out of six swab samples taken from
the lined surface. It is possible that spores penetrated or diffused through the spray on coating,
but these spores could also be the result of cross contamination from the site or from the pipe
during the coating process. No spores were detected after chlorination. In the iron pipe, no
spores were detected after pigging, likely because they were removed with the corrosion
material. This data suggests that relining is needed more for cement lined pipes than unlined
pipes which have been pigged by this method. Pigging alone was not sufficient to remove all
BG spores from the cement lined pipe even after the chlorination step, so this type of pipe might
require further remediation or relining.
3.3 Warthog pigging with CiPP pipe relining
The background HPC concentration on the cement-mortar lined and corroded iron inner pipe
surfaces were analyzed via two scrape samples. These samples were removed after wetting the
pipes with tap water, but before contamination with spores and decontamination with pigging.
Mean HPC values from the two scrape samples from cement-mortar lined (Figure 25) and
corroded iron pipes (Figure 26) were 2.4 x 105 most probable number (MPN)/cm2 and 2.8 x 105
MPN/cm2, respectively. These results indicate that viable biofilm was present on the pipe walls
prior to the initiation of the tests.
24

-------
l.E+06
l.E+os
3
H—
r l-E+04
c
o
EL
3
O
u
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l.E+03
l.E+02
tn
C
at
u
aj
l.E+01
g 1.E+00
Q.
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CO
Post Pigging:
Spores
detected on 2
out of 4
samples
Post Chlorine:
Spores
detected on 1
out of 4
samples
i Pre-BG injection Spore Density, n=2
Spore Density During BG Injection, n=4
Post-BG Injection, Pre-Pigging Spore Density, n=4
Post Pigging Spore Density, n=6
Post Pipe Relining, n=4
Post Chlorination Spore Density, n=4	
T
LOD: 1.9 cfu/cm2)
Figure 25: Decontamination of Bacillus globigii (BG) from the cement-mortar lined iron
pipe section with the Warthog nozzle and CIPP relining
Post Pigging:
Spores
detected on 2
out of 4
samples
Post Chlorine:
Spores
detected on 1
out of 4
samples
I Pre-BG injection Spore Density, n=2
Spore Density During BG Injection, n=4
Post-BG Injection, Pre-Pigging Spore Density, n=
Post Pigging Spore Density, n=6
i Post Pipe Relining, n=4
Post Chlorination Spore Density, n=4	
T
LOD: 1.9 cfu/cm2)
Figure 26: Decontamination of Bacillus globigii (BG) from the corroded iron pipe section
with the Warthog nozzle and CIPP relining
The first bar (pre-BG injection spore density) in Figure 25 and Figure 26 reflect samples taken
before contamination with spores. In both figures, spores are present. The pipes were not in
contact with spores before contamination. However, previous experiments may have
contaminated the surrounding area with spore forming bacteria. The pipes sat open on the site
25

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for approximately 4 weeks before experiments began. Therefore, it is possible that spore
contaminated dirt or dust blew into the pipe, and spores were not washed off when the pipes
were wetted for HPC sampling.
The second bar (spore density during BG injection) represents the number of viable spores
detected on the pipe surface immediately after spore contamination. The bulk water phase had
1.3 x 106 and 6 .9 xlO5 CFU/mL during contamination in the cement-mortar and corroded iron
pipe, respectively. The pipes were contaminated, drained, sampled, and then filled with tap water
until pigging took place the next day. The third bar (Post-BG injection) represents the number of
viable spores attached to the pipe surface immediately before pigging took place. Any decrease
between the second and third bar represents the number of spores that came off the pipe surface
between contamination and immediately before pigging. The fourth bar (Post pigging BG spore
density) represents the number of viable B. globigii spores attached to the pipe surface after
pigging. The fifth bar (Post pipe relining) summarizes the number of viable B. globigii spores
recovered from the inner pipe surface after relining. The last bar (Post chlorination spore
density) represents the number of viable spores recovered from pipe surface after chlorination.
Figure 25 shows the Warthog pigging and CIPP relining results for the cement mortar lined pipe.
Pigging with the Warthog nozzle resulted in 2.2 log removal of spores from the pipe surface.
Relining with CIPP reduced the number of viable spores detected by 1.8 log. Chlorination
resulted in an additional 0.3 log reduction, for a combined total of 4.3 log reduction. Viable
spores were found in one out of four swab samples taken from the inner pipe surface after
chlorination. Figure 26 shows the Warthog pigging and CIPP relining results for the cement
mortar lined pipe. Pigging with the Warthog nozzle resulted in 2.8 log removal of spores from
the pipe surface. Relining with CIPP reduced the number of viable spores detected by 1.7 log.
Chlorination resulted in an additional 0.8 log reduction, for a total reduction of 5.3 log. Viable
spores were found in one out of four swab samples taken from the pipe surface after chlorination.
During the chlorination phase, aliquots of chlorine bleach were added to the pipe sections with
the goal of achieving 70 to 80 mg/L free chlorine. In the relined cement-mortar pipe, the initial
free chlorine concentration was 215 mg/L. After 16.75 hours of contact, the free chlorine
concentration was 69 mg/L. These values yield a bulk phase CT of 307,715 mg-min/L. In the
corroded iron pipe, the initial free chlorine concentration was 210 mg/L. After 16.75 hours of
contact, the free chlorine concentration was 59 mg/L. These values yield a bulk phase CT of
304,778 mg-min/L. No viable spores were detected in the bulk water phase after the bleach had
been flushed from the pipe and tap water restored.
The results shown in Figure 25 and Figure 26 suggest that pigging, relining with CIPP and
chlorination are effective at yielding an inner pipe surface with substantially fewer adhered
spores. In both types of pipe, spores were detected in 1 out of 4 sample after chlorination. The
CIPP lining is approximately 1.3 cm (0.5 in) thick and resembles a plastic or PVC pipe. It is
unlikely that spore could transfer or diffuse through this material. The presence of spores on the
CIPP surface is likely due to cross contamination from the surrounding site, or transfer from the
pipe itself to the surface during CIPP installation. Installing the CIPP requires more handling
and manipulation of the impregnated sock material as compared to the spray on pipe lining. It
was noted that there were dirty or "greasy" spots on the CIPP surface that were sampled, and it is
26

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possible that these areas could harbor spores. This could have made cross contamination of the
CIPP relined pipe more likely than the pipe relined with the Oceanit method.
3.4 Results Summary Tables
Table 2 shows a summary of the total BG log reduction after the three decontamination methods
on cement-mortar lined iron pipe and unlined ductile iron pipe. Table 2 is meant to be a quick
summary of the overall effectiveness of each decontamination method.
Table 2: Summary of total BG spore log reduction from each decontamination method
tested on two difi
erent pipe types.
Decontamination Method
Cement-Mortar
Lined Iron Pipe
Total Log
Reduction
Unlined Iron
Pipe Total
Log
Reduction
Warthog Pigging followed by
chlorination
3.0
>5.8
Warthog pigging following by
Oceanit DragXthen chlorination
>5.9
>6.5
Warthog pigging following by
CIPP relining then chlorination
4.3
5.3
Table 3 shows the log reduction for each individual process in the three decontamination
methods. Showing the effectiveness of each decontamination process side by side displays
important points about their implementation in the field. First, Warthog pigging was performed
on three cement-mortar lined ductile iron, and three unlined ductile iron pipes. However, the
data in Table 3 shows that pigging alone was not equally effective on each pipe of the same type.
BG spore log reduction ranged from 1.9 to 4.0 on cement-mortar lined iron pipe, and 2.8 to >6.5
on unlined iron pipe. This comparison shows that the decontamination effectiveness of pigging
may be influenced by the number of initial spores adhered, but also possibly by how well the
operator was able to pig the pipe, as well as factors that are unknown. However, the ranges
listed above for each type of pipe could be used as a range of effectiveness for pigging with a jet
spray type pig.
It should also be noted that after relining and chlorination, spores were still sometimes detected
on the lined pipe surface. It is doubtful that this is due to spores penetrating through the lining.
As noted earlier, the presence of spores is likely due to cross contamination from the surrounding
site, or transfer from the original pipe to the lining surface during installation. In this study,
spores were not detected on the Oceanit lining, but were detected on the CIPP lining. It is
unclear if this result is a function of the lining itself or if it is a coincidence. However, the data
suggest that both pipe relining technologies have the potential to be effective.
27

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Table 3: Summary of the BG spore log reduction for each step the decontamination
processes on two different pipe types.	

Lo
g Reduction

Adhered





# of spore
Pipe Type
Spore
Density
Before
Pigging
(cfu/cm2)
After
Warthog
Pigging
+Oceanit
DragX
Relining
+CIPP
Relining
+Chlorination
Total Log
Reduction
positive
sample
after final
decon
method
Cement-
1.0x10s
1.9


1.1
3.0
3/4
Mortar
8.3x10s
4.0
1.4

>0.5
>5.9
0/4
Lined Iron
Pipe
5.1xl04
2.2

1.8
0.3
4.3
1/4
Unlined
Iron Pipe
5.7x10s
4.9


>0.9
>5.8
0/4
8.3x10s
>6.5
N/A

N/A
>6.5
0/4
4.2x10s
2.8

1.7
>0.8
5.3
1/4
Darkened boxes indicate that the decontamination procedure was not used.
BG, Bacillus globigii; CIPP, cured in place pipe; N/A: not applicable as spores were not detected.
4.0 Conclusions
Decontaminating adhered Bacillus spores from drinking water infrastructure can be challenging.
This study examined the ability of pigging, or physical scouring of the inside of pipes, as well as
pipe relining followed by chlorination, to reduce the number of viable Bacillus spores that were
detectable on the inner pipe surface. A summary of the three different decontamination
processes on two different pipe types are as follows:
•	Warthog pigging (2,300 psi, 70 gpm) of an individual cement-mortar lined iron pipe
section resulted in a 1.9-log reduction of the number of spores detected on the inner pipe
surface. After pigging, chlorination of the water in the pipe at an initial concentration of
149 mg/L (111 mg/L after 18.25 hours) resulted in an additional 1.1-log inactivation of
the spores adhered to the pipe inner surface, for a total reduction of 3.0-log.
•	Warthog pigging (2,300 psi, 70 gpm) of an individual corroded iron pipe section resulted
in a 4.9-log reduction of the number of spores detected on the inner pipe surface. After
pigging, chlorination of the water in the pipe at an initial concentration of 82 mg/L (39
mg/L after 18.25 hours) resulted in an additional 0.9-log inactivation of the spores
adhered to the pipe inner surface, for a total reduction of 5.8-log.
•	Warthog pigging (2,300 psi, 70 gpm) followed by Oceanit DragX relining of an
individual cement-mortar lined iron pipe section resulted in a 5.4-log reduction of the
number of spores detected on the inner pipe surface (note that spores were only detected
in 2 out of 6 pipe interior samples). After relining, chlorination of the water in the pipe at
an initial concentration of 216 mg/L (133 mg/L after 22.15 hours) resulted in no spores
detected on the interior pipe surface, or up to an additional 0.5-log inactivation of the
spores adhered to the pipe inner surface, for a total reduction of > 5.9-log.
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•	Warthog pigging (2,300 psi, 70 gpm) followed by Oceanit DragX relining of an
individual corroded iron pipe section resulted in no spores detected on the inner pipe
surface, or > 6.5-log reduction. After relining, chlorination of the water in the pipe at an
initial concentration of 171 mg/L (122 mg/L after 22 hours) still resulted in no spores
detected on the interior pipe surface.
•	Warthog pigging (2,300 psi, 70 gpm) followed by CIPP relining of an individual cement-
mortar lined iron pipe section resulted in a 4.0-log reduction of the number of spores
detected on the inner pipe surface (note that spores were only detected in 2 out of 4 pipe
interior samples after relining). After relining, chlorination of the water in the pipe at an
initial concentration of 215 mg/L (69 mg/L after 16.75 hours) resulted in an additional
0.3-log inactivation of the spores adhered to the pipe inner surface, for a total reduction
of 4.3-log. Spores were detected in 1 out of 4 post chlorination pipe interior samples, and
their presence was likely due to cross contamination.
•	Warthog pigging (2,300 psi, 70 gpm) followed by CIPP relining of an individual
corroded iron pipe section resulted in a 4.5-log reduction of the number of spores
detected on the inner pipe surface (note that spores were only detected in 2 out of 4 pipe
interior samples after relining). After relining, chlorination of the water in the pipe at an
initial concentration of 210 mg/L (59 mg/L after 16.75 hours) resulted in an additional
0.8-log inactivation of the spores adhered to the pipe inner surface, for a total reduction
of 5.3-log. Spores were detected in 1 out of 4 post chlorination pipe interior samples, and
were likely due to cross contamination.
Pigging with the Warthog nozzle followed by chlorination reduced spores on cement-mortar
lined iron by 3.0-log, and by 5.8 log on corroded iron. Increased decontamination efficacy on
corroded iron compared to cement-mortar lined iron was likely due to spores being adhered to
the corroded iron matrix, which as almost completely removed during pigging process. After
both relining process were complete, spores were nearly undetectable. Any detectable spores
present after relining (and chlorination) were likely due to cross contamination of spores from
the surrounding area or carry over from the contaminated pipe. For pipe relining to be
successful, cross contamination would need to be controlled.
Should a biological contamination scenario occur, a technique like pipe lining or replacement
could be implemented to ensure that human exposure to spores via drinking water does not
occur. Pigging, relining and chlorination can substantially reduce the number of spores adhered
to drinking water infrastructure, which may make further remedial actions easier. It should also
be considered that pigging generates contaminated waste and wash water, which must be treated
or disposed of properly. First responders and decision makers should weigh the burden of
contaminated water and waste generation against the decontamination efficiency of pigging,
chlorination and pipe relining.
It should also be noted that the skill and experience of the operators applying either pigging or
pipe relining techniques are important. There is an art to "working the pigs" effectively through
the pipeline, or successfully applying a pipe coating. The speed of the nozzle is controlled by the
operator and certain sections of pipe may require several passes or rework as the pig progresses
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through the pipe. The degree of decontamination resulting from pigging or pipe relining can vary
depending on the skill of the operator.
The authors acknowledge that the decontamination and rehabilitation methods used in this report
require more time and resources than typical chlorination and flushing response actions. These
methods also require more specialized equipment and expertise, and would be more expensive to
implement. Worker safety, contamination of utility owned equipment, and disposal of
contaminated water and debris are other areas that need to be considered before implementing
water jet pigging as a decontamination method. However, in areas where flushing and
chlorination are ineffective, and pipe replacement is challenging, water jet pigging and/or pipe
relining may be the only decontamination option.
All of the pipe decontamination and rehabilitation methods described in this report were intended
for use on larger diameter (e.g. 4 inches or larger) drinking water utility owned piping.
However, any contamination event that impacts the larger utility owned pipes under the street
will likely impact the end users of the water supply. Additional research is needed to assist home
owners and post service connection water customers with decontamination of their service lines,
home plumbing and appliances. These pipe diameters are often 1 inch or less with numerous
bends and valving. Several technologies are emerging for service line relining, and these
relining methods should be tested as a way to contain residual spore contamination. Finally, it
should be noted that a hole must be drilled in the Permaliner used in this study in order to insert a
new home or building water service connection. It is possible that contamination trapped
between the Permaliner and pipe wall could be released when a new service connection is cut.
Research into how to avoid service connection contamination when installing a new service
connection should be conducted.
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5.0 References
APHA (American Public Health Association), (2005). Standard Methods for the Examination of
Water and Waste Water, Method 9125, 21st edition. Washington, DC: American Public
Health Association.
AWWA (American Water Works Association), (2005). Standard C651-05: Disinfection of
Water Mains. Denver, Co: American Water Works Association.
Beck, R. A.; Buttle, J. L.; and Wolfe, T. A. (1983). Water-jet technique used to clean encrusted
pipe. Opflow, 9(5), 6-7.
Szabo, J.G.; Meiners, G.; Heckman, L.; Rice, E.W.; and Hall, J., 2017. Decontamination of
Bacillus spores adhered to iron and cement-mortar drinking water infrastructure in a
model system using disinfectants. Journal of Environmental Management, 187:1.
Szabo, J.G., Hall, J., Goodrich, J. and Ernst, H., 2017a. Full scale drinking water system
decontamination at the Water Security Test Bed. Journal of the American Water Works
Association, 109 (12), E535-E547
USEPA (U.S. Environmental Protection Agency), 2016. Water Security Test Bed Experiments at
the Idaho National Laboratory. EPA/600/R-15/146, Washington DC: U.S. Environmental
Protection Agency.
USEPA (U.S. Environmental Protection Agency), 2018. Decontamination of Bacillus Spores
from Drinking Water Infrastructure with Physical Removal (Pigging). EPA/600/R-
18/078, Washington DC: U.S. Environmental Protection Agency.
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