Page 312 - Water Engineering Hydraulics, Distribution and Treatment

290
Chapter 9
Cross-Connection Control
The water supply company may elect to work initially on
tem. By so doing, the water supplier can assess the overall
the “containment” theory. This approach utilizes a minimum
of backflow devices and isolates the customer from the water
nature of the facility and its potential impact on the water
system (determine the degree of hazard), personally see
main. It virtually insulates the customer from potentially
contaminating or polluting the public water supply system.
actual cross-connections that could contaminate the water
Although that type of “containment” does not protect the
system, and take appropriate action to ensure the elimina-
customer within his own building, it does effectively remove
tion of the cross-connection or the installation of required
backflow devices.
him from possible contamination to the public water supply
Assisting the water supplier in the total administration
system.
If the water supplier elects to protect its customers on
of a cross-connection control program requires that all pub-
lic health officials, plumbing inspectors, building managers,
a domestic internal protective basis and/or “fixture outlet
protective basis,” then cross-connection control protective cross-connections in order to protect the potable water sys-
plumbing installers, and maintenance personnel participate
devices are placed at internal high hazard locations as well and share in the responsibility of protecting the public health
as at all locations where cross-connections exist at the “last and safety of individuals from cross-connections and con-
free-flowing outlet.” This approach entails extensive cross- tamination or pollution of the public water supply system.
connective survey work on behalf of the water superintendent
as well as constant policing of the plumbing within each
commercial, industrial, and residential account. 9.6.2 Dedicated Line
In large water supply systems, fixture outlet protection
In addition to the options just discussed, Fig. 9.29 also depicts
cross-connection control philosophy, in and of itself, is a vir-
the use of a “dedicated” potable water line. This line ini-
tual impossibility to achieve and police due to the quantity
tiates immediately downstream of the water meter and is
of systems involved, the complexity of the plumbing sys-
“dedicated” solely for human consumption: drinking foun-
tems inherent in many industrial sites, and the fact that many
tains, safety showers, eye wash stations, and so on. It is very
plumbing changes are made within industrial and commer-
important that this piping be color coded throughout in accor-
cial establishments that do not require the water department
dance with local plumbing regulations, flow direction arrows
to license or otherwise endorse or ratify when contemplated
added, and the piping religiously policed to ensure that no
or completed.
cross-connections to other equipment or piping are made that
In addition, internal plumbing cross-connection control
could compromise water quality. In the event that authorities
survey work is generally foreign to the average water supplier
feel the policing of this line cannot be reliably maintained or
and is not normally a part of its employees’ job descriptions
enforced, the installation of a containment device on this line
or duties. Although it is admirable for the water supplier
should be considered.
to accept and perform survey work, the supplier should be
aware that it runs the risk of additional liability in an area that
may be in conflict with plumbing inspectors, maintenance 9.6.3 Method of Action
personnel, and other public health officials.
Even where extensive “fixture outlet protection” cross- A complete cross-connection control program requires a
connection control programs are in effect through the efforts carefully planned and executed initial action plan followed
of an aggressive and thorough water supply cross-connection by aggressive implementation and constant follow-up. Proper
control program, the water authorities should also have an staffing and education of personnel is a requirement to ensure
active “containment” program in order to address the many that an effective program is achieved. A recommended plan of
plumbing changes that are made and that are inherent within action for a cross-connection control program should include
commercial and industrial establishments. In essence, fixture the following characteristics:
outlet protection becomes an extension of the “containment”
program. 1. Establish a cross-connection control ordinance at the
Also, in order for the water supplier to provide maximum local level and have it approved by the water com-
protection of the water distribution system, consideration missioners, town manager, and so on, and ensure that
should be given to requiring the owner of a premise (com- it is adopted by the town or private water authority as
mercial, industrial, or residential) to provide, at his/her own a legally enforceable document.
expense, adequate proof that his/her internal water system 2. Conduct public information meetings that define the
complies with the local or state plumbing code(s). In addition, proposed cross-connection control program, review
he/she may be required to install, have tested, and maintain the local cross-connection control ordinance, and
all backflow protection devices that would be required—at answer all questions that may arise concerning the
his/her own expense. reason for the program, why and how the survey will
The water supplier should have the right of entry be conducted, and the potential impact on industrial,
to determine the degree of hazard and the existence of commercial, and residential water customers. Have