Chapter 1: General

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1.1 Purpose

The purpose of this document is to provide the minimum requirements for design, operation, maintenance and testing to prevent legionellosis associated with building water systems in federal buildings.

1.2 Scope

The target audience for this document is property managers, project managers, design professionals, maintenance personnel, and property owners.

This standard applies to all Crown-owned buildings, except remote residential housing, that are managed by Public Works and Government Services Canada (PWGSC) and/or its service providers.

In this standard the word “shall” is used to express a requirement that the user is required to satisfy in order to comply with this standard. The word “should” is used to express a recommendation that is advised but is not a requirement for compliance with this standard.

Unless noted otherwise in this document, mechanical systems within Government of Canada buildings shall be designed, constructed, and operated consistent with industry standards and best practices for the prevention and control of Legionella bacteria. These include the requirements of the latest versions of the National Building Code of Canada, the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) Guideline 12: Minimizing the Risk of Legionellosis Associated with Building Water Systems, Cooling Technology Institute (CTI) Guidelines WTB-148: Best Practices for Control of Legionella, Quebec regulations for cooling towers, ASHRAE Standard 188: Legionellosis: Risk Management for Building Water Systems and the American Industrial Hygiene Association (AIHA) Recognition, Evaluation and Control of Legionella in Building Water Systems.

Equipment such as cooling towers shall be registered with all applicable provincial and municipal equipment registries.

Where this standard conflicts with the requirements of applicable legislation or regulations, the most stringent requirement shall take precedence.

This standard provides the minimum requirements that must form part of a facility's Legionella Bacteria Control Management Program (LBCMP).

Checklists and forms shall be used to ensure the consistent implementation and reporting of the facility's LBCMP.

Personnel must take all necessary health and safety precautions including the use of personal protective equipment when taking water samples for bacterial testing, and cleaning or disinfecting systems.

1.3 Definitions

Action Limit
For test results, the limit at which a corrective action is required.
A suspension in a gaseous medium of solid particles, liquid particles, or solid and liquid particles having negligible falling velocity. Airborne water particles are usually less than 5 micron in diameter and are breathable into the lower areas of the lungs.
Small, usually aquatic, plants which require light to grow. They are often found growing on the exposed surfaces and edges of cooling towers, and in open air water tanks.
The growth of Legionella bacteria from a low concentration to a high concentration, usually at amplification sites.
Plural of bacterium; see below.
A microscopic unicellular organism, capable of independent growth.
A substance that kills micro-organisms.
The concentration of nutrients and microorganisms in the interface between liquid and solid surfaces. Can readily accept Legionella bacteria.
Water discharged from a cooling tower water system to control the concentration of salts and other impurities in the circulating water. Usually expressed as a percentage of the recirculating water flow.
Removal of sediments, sludge, and debris by physical means.
To add chlorine to the water, often in the form of sodium hypochlorite.
Cooling tower
An apparatus or system through which warm water is discharged against an air stream, and in doing so evaporation occurs and cools the water.
Cooling tower drift
Drift of water droplets from a cooling tower.
Corrosion inhibitor
A chemical designed to prevent or slow down the corrosion of metals, generally in piping.
Dead leg
A length of pipe containing water, temporarily or permanently blocked at one end.
A cleansing agent capable of penetrating biological films, sludge, and sediment and having the ability to emulsify oil and hold materials in suspension.
A glass or plastic slide coated with culture media on which microorganisms can be grown and estimated.
Reduction of population of microorganisms using chemical or physical means. Not necessarily the same as sterilization.
A chemical usually added with other treatment chemicals to loosen organic material adhering to surfaces and prevent accumulation of sludge.
A mechanism that permits transfer of Legionella from the reservoir to the point of exposure to people.
The water aerosol that emerges from the airflow outlet of a cooling tower. It is distinct from “plume.”
Drift eliminator
Equipment containing a complex system of baffles designed to remove water aerosols.
Evaporative cooler
A device that provides cooling by evaporation of water in an airstream.
Evaporative condenser
Equipment that circulates water to wet a condenser coil and directs air over the coil to provide evaporative cooling.
Organic growth or other deposits on heat transfer surfaces causing loss of heat-transfer efficiency.
Free chlorine
Free chlorine refers to the active form of chlorine that is available as a disinfectant, as opposed to the “combined” form of chlorine that is not available for disinfection. For example, salt water has no free chlorine; it is all combined as sodium chloride. Free chlorine generally refers to the hypochlorous and the hypochlorite ions in aqueous solutions, and is measured in ppm.
Generic name for chlorine, bromine, and iodine according to the periodic table.
Any source of potential damage, harm or adverse health effects
Humidifier (non-steam)
A non-steam humidifier is a unit that does not convert water to vapour for humidification by exposing the water to an elevated temperature. Non-steam humidifcation systems may contain a sump for collecting excess spray water which may be re-circulated. Non-Steam humidifiers include system types such as air washers, misters and wetted media.
Humidifier (steam)
A steam humidifier is a unit that converts water to vapour for humidification by exposing water to an elevated temperature. Water droplets are not generated by the humidification process.
A genus of bacterium causing Legionnaires' disease.
Legionella Bacteria Control Management Program (LBCMP)
The program established for each building with a specific system risk assessment/analysis of each Legionella Susceptible System, with a program for maintenance and testing based on either ASHRAE or CTI guidance documents.
Legionnaires' disease
An illness characterized by pneumonia, caused by infection with Legionella species such as Legionella pneumophila.
Legionella Susceptible Systems
Water systems in a building that pose the risk of Legionella amplification.
Another name for Legionnaires' disease.
Acronym for “minimum efficiency reporting value.” The MERV rating is the standard method for comparing the efficiency of an air filter. The higher the MERV rating, the better the filter is at removing particles from the air.
A chemical that is oxidizing in nature, such as chlorine
Two or more cases of a disease linked by a common cause.
A scale used to describe the hydrogen ion concentration in aqueous solutions. Pure water has a pH of 7. A smaller value indicates an acidic condition; a number greater than 7 is alkaline. The range of pH values is 0–14.
A cloud of water vapour emerging from a cooling tower. It is not the same as “drift.”
Pontiac fever
A self-limited short-duration, non-fatal fever caused by Legionella bacteria. The incubation period of the disease is from 5 hours to 66 hours, and the attack rate is up to 95%. Symptoms include chills, headache, muscle pain, and other flu-like symptoms.
Potable water
Water that is suitable for consumption by building occupants.
The chance or probability that a person will be harmed or experience an adverse health effect if exposed to a hazard.
Running Disinfection
Rapidly raising the biocide level in the system to kill the bacteria that is present without shutting down, cleaning or draining the water from the system. The required biocide level and quantity of additional biocide is to be determined by a water treatment specialist.
Scale inhibitor
Chemical added to water to inhibit formation of scale.
A mucous-like material that is produced as part of an organism's metabolism and allows adherence of a protective layer to surfaces.
A general term for soft mud-like deposits on heat-transfer surfaces or other important sections of a cooling system.
Sodium hypochlorite
A chlorine-releasing water soluble chemical used for disinfection.
A soluble surface acting agent that reduces surface tension of water.
Stagnant Water
Water that has little or no movement or activity.
The process of eliminating all disease-causing organisms in a piece of equipment. Sterilization is not necessarily the same as disinfection
Total bacteria count (TBC)
An estimate of the number of viable units of bacteria per millilitre of water under the conditions of testing.
Utility water system
A building water distribution system that provides water intended for uses other than human consumption.
The element of verification focused on collecting and evaluating scientific and technical information to determine if the Management Program, when properly implemented, will effectively control the hazards. Obtaining evidence that the elements of the Legionella Bacteria Control Management Program are effective.
Those activities, other than monitoring, that determine the validity of the Management Program and whether the system is operating according to the plan. The application of methods, procedures, tests, and other evaluations, in addition to monitoring, to determine compliance with the Legionella Bacteria Control Management Program.
Physical loss of water from the base of a cooling tower caused by wind of unusual pattern passing through it.

1.4 Acronyms

Advisory and Practices (Professional Services)
American Society of Heating, Refrigerating and Air-Conditioning Engineers
Colony forming unit
Cooling Technology Institute
Environmental Protection Agency
Genome equivalents per millilitre
Legionella Bacteria Control Management Program
Legionella pneumophila serogroup 1
Legionella pneumophila including all serogroups
Minimum efficiency reporting value
Milligrams per litre
National Capital Area
Non-Legionella Pneumophila Legionella bacteria, rarely involved in Legionella infection
Operation and maintenance
Occupational Safety and Health Agency
PCR Test
Polymerase chain reaction test; also see qPCR Test
Professional and Technical Service Management
Parts per million
qPCR Test
Quantitative PCR Test; reporting units are GE/mL
Total bacteria count

1.5 Roles and responsibilities

Table 1.1: Roles and responsibilities

Director General, Professional and Technical Service Management

Regional Directors General; Director General National Capital Area Operations

Facility manager/Facility manager for service providers

1.6 Legionella bacteria control management program

1.7 Personal protective equipment

Personnel must take all necessary health and safety precautions including the use of personal protective equipment when taking water samples for bacterial testing, and cleaning or disinfecting systems.

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