We
would like to belong to your list of Approved Backflow Device Testers.
We would be pleased to assist you with the installation,
maintenance or certification of your devices.
Please call our Office to schedule an appointment at
970-453-1950. We are also available to answer any of your questions
on this topic.
Below
is additional information regarding a few reported
incidents that portray the serious problems that can occur if proper
backflow prevention programs and/or devices are not in place.
*American
Backflow Prevention Association
EXAMPLE
BACKFLOW INCIDENTS
DATE OF BACKFLOW INCIDENT: October
1986
LOCATION OF BACKFLOW INCIDENT: Lacey's Chapel, Alabama
SOURCE(S) OF INFORMATION:
- Pacific Northwest Section of the American Water Works Association,
Summary of Backflow Incidents, Fourth Edition, 1995
- U.S. Environmental Protection Agency, Cross-Connection Control
Manual, 1989
- Watts Industries, Inc.; Watts Regulator News/Stop Backflow
CASE
HISTORY
On Wednesday, October 8, 1986, an
eight-inch-diameter water main of the Bessemer Water Service broke in
Lacey's Chapel, Alabama. While repairing the water main, one Bessemer
Water Service worker suffered leg burns from an unidentified chemical
and required medical treatment.
Wednesday
night and early Thursday, the Bessemer Water Service received several
complaints from the area of Lacey's Chapel served by the broken water
main. Some residents complained of burned throats or mouths after
drinking the water. Tiny red blisters covered one resident's body
after he got out of the shower on Thursday morning. He and several
other residents received medical treatment at the emergency room of
the local hospital. The Bessemer Water Service shut down water service
to the area at 7:00 A.M. on Thursday and initiated an investigation.
Sodium hydroxide, a caustic chemical, had backflowed into the public
water system from a nearby chemical plant.
The
chemical plant distributed chemicals such as sodium hydroxide. Sodium
hydroxide was brought to the plant as a liquid in bulk tanker trucks
and was transferred to a holding tank and then pumped into 55-gallon
drums. When the water main broke on Wednesday, a truck driver was
adding water to a tanker truck that had carried sodium hydroxide. On
this occasion, the driver was filling the tanker from a connection at
the bottom of the tanker. Consequently, the sodium hydroxide in the
tanker was backsiphoned into the public water system when the water
main broke.
About
60 homes in the area of the broken water main received contaminated
water. Measurements of pH were as high as 13 in some homes. The
Bessemer Water Service flushed water mains, and health officials made
sure that all plumbing was flushed.
There
was no backflow preventer at the water service connection to the
chemical plant. The Bessemer Water Service did not have a
cross-connection control program although State regulations required
public water systems to have such a program.
DATE OF BACKFLOW INCIDENT: June
1983
LOCATION OF BACKFLOW INCIDENT: Woodsboro, Maryland
SOURCE(S) OF INFORMATION:
- Pacific Northwest Section of the American Water Works Association,
Summary of Backflow Incidents, Fourth Edition, 1995
- U.S. Environmental Protection Agency, Cross-Connection Control
Manual, 1989
- Watts Industries, Inc.; Watts Regulator News/Stop Backflow
CASE
HISTORY
In June 1983, "yellow gushy
stuff" poured from some faucets in the Town of Woodsboro,
Maryland. Town personnel notified the County Health Department and the
State Water Supply Division. The State dispatched personnel to take
water samples for analysis and placed a ban on drinking the Town's
water. Firefighters warned residents not to use the water for
drinking, cooking, bathing, or any other purpose except flushing
toilets. The Town began flushing its water system. An investigation
revealed that the powerful agricultural herbicide Paraquat had
backflowed into the Town's water system.
Someone
left open a gate valve between an agricultural herbicide holding tank
and the Town's water system and, thus, created a cross-connection.
Coincidentally, water pressure in the Town temporarily decreased due
to failure of a pump in the Town's water system. The herbicide
Paraquat was backsiphoned into the Town's water system. Upon
restoration of pressure in the Town's water system, Paraquat flowed
throughout much of the Town's water system.
Fortunately,
this incident did not cause any serious illness or death. The incident
did, however, create an expensive burden on the Town. Tanker trucks
were used temporarily to provide potable water, and the Town flushed
and sampled its water system extensively.
DATE OF BACKFLOW INCIDENT: January
1990
LOCATION OF BACKFLOW INCIDENT: Brighton, Colorado
SOURCE(S) OF INFORMATION:
- Pacific Northwest Section of the American Water Works Association,
Summary of Backflow Incidents, Fourth Edition, 1995
- Watts Industries, Inc.; Watts Regulator News/Stop Backflow
CASE
HISTORY
On January 30, 1990, authorities
closed Overland Middle School in Brighton, Colorado, after an
antifreeze-like chemical was found in the school's potable water
system. They sent nine students complaining of flu-like symptoms to an
area hospital for treatment. The hospital released the students after
treating them for ethylene glycol poisoning. Ethylene glycol had
backflowed into the school's potable water system from the school's
hot-water heating system.
During
a routine maintenance check of the Overland Middle School's hot-water
heating boiler, maintenance workers left open a valve on the potable
water line feeding the boiler. This allowed boiler water containing
the antifreeze ethylene glycol to backflow into the school's potable
water system. There was no backflow preventer on the feed line to the
boiler.
The
Overland Middle School was closed for an additional day while workers
flushed the potable water piping at the school and "repaired the
hot-water heating system leak." Presumably workers installed a
proper backflow preventer in the potable water line feeding the
hot-water heating boiler.
DATE OF BACKFLOW INCIDENT: December
1983
LOCATION
OF BACKFLOW INCIDENT: San Antonio, Texas
SOURCE(S) OF INFORMATION:
- American Water Works Association, Recommended Practice for Backflow
Prevention and Cross-Connection Control, AWWA Manual M14, Second
Edition, 1990
CASE
HISTORY
In December 1983, effluent from a
wastewater treatment plant in San Antonio, Texas, backflowed into the
potable water system at the plant because of maintenance activities.
Eight
employees reportedly suffered gastrointestinal problems. Fortunately,
a reduced-pressure principle backflow-prevention assembly was in place
at the water service connection to the plant. This assembly contained
contamination within the plant site.
DATE OF BACKFLOW INCIDENT: August
1982
LOCATION OF BACKFLOW INCIDENT: Connecticut
SOURCE(S) OF INFORMATION:
- Pacific Northwest Section of the American Water Works Association,
Summary of Backflow Incidents, Fourth Edition, 1995
- U.S. Environmental Protection Agency, Cross-Connection Control
Manual, 1989
- Watts Industries, Inc.; Watts Regulator News/Stop Backflow
CASE
HISTORY
In August 1982, residents in a
Connecticut town reported hissing, bubbling noises coming from washing
machines, sinks, and toilets. Faucets sputtered out small streams of
water mixed with gas. Propane gas had backflowed into the town's
public water system. Local firefighters and other officials asked
hundreds of residents to evacuate their homes and businesses.
The
town provided water to a propane storage facility in the area. Water
was furnished to the facility for both domestic use and fire
protection and entered the facility through a single
eight-inch-diameter service connection. The facility included 26
subsurface 30,000-gallon liquid propane storage tanks.
On
the day of the backflow incident, workers needed to repair a storage
tank at the propane storage facility. Before repairing the tank,
workers had to purge the tank of residual propane. There are two
common methods for purging liquid propane storage tanks. One method is
to use an inert gas such as carbon dioxide. The other method is to use
water. The use of water is the preferred method because it is a more
positive method and will float out any sludge as well as gas vapors.
Accordingly, workers attempted to purge the tank using water in this
case. They connected a hose to the tank from one of the two fire
hydrants at the facility. Unfortunately, the pressure in the propane
tank was about 85 to 90 psig, while the pressure in the town's public
water system was about 65 to 70 psig. Consequently, propane gas
backflowed into the town's public water system. It was estimated that
about 2,000 cubic feet of gas flowed into the water system over a
period of about 20 minutes. This is enough gas to fill approximately
one mile of eight-inch-diameter water main.
Fires were reported at two houses, and fire
gutted one of these houses. At another house, a washing machine
exploded. Police, propane company workers, and town water works
personnel, however, limited damage and injuries by quickly sealing off
the affected area. The town flushed fire hydrants and individual
building plumbing systems and monitored for gas. The propane company
promptly instituted revised propane tank purging procedures at its
storage facility.
