DEPARTMENT OF DEFENCE DEFENCE ESTATE QUALITY MANAGEMENT SYSTEM MECHANICAL ENGINEERING MICROBIAL CONTROL IN AIR HANDLING AND WATER SYSTEMS OF DEFENCE BUILDINGS August 2012 DOCUMENT STATUS Version No. Issue Date 1 2 3 4 May 2012 July 2012 Aug 2012 Aug 2012 Page 2 of 28 Amendment Details Draft for review and comment Review comments incorporated DEMP review comments incorporated Version issued for publish Amended by TML TML TML TML August 2012 version 4 CONTENTS 1.0 INTRODUCTION 1.1 1.2 4 Aim Sponsor 4 4 2.0 POLICY OBJECTIVES AND PRINCIPLES 2.1 2.2 5 Policy Objectives Policy Principles 5 5 3.0 APPLICATION 6 4.0 STANDARDS GUIDELINES AND CODES OF PRACTICE 7 4.1 4.2 Standards Codes Regulations and Legislation Guidelines and Application Manuals 5.0 DEFINITIONS 7 7 9 6.0 LEGIONELLA BACTERIA 11 7.0 MICROORGANISM MANAGEMENT AND CONTROL 13 8.0 COOLING WATER SYSTEMS 14 8.1 8.2 8.3 8.4 8.5 8.6 8.7 Approach to Maintenance Prescriptive Maintenance Requirements Performance-Based Maintenance Requirements Existing Equipment Upgrade Intermittent and Seasonal Equipment Use Start-Up and Shut-Down Instructions Retention of Records 9.0 WATER SYSTEMS 9.1 9.2 9.3 14 14 15 17 17 17 18 19 General Water Treatment Products Proprietary Water Treatment Devices 19 19 20 10.0 AIR HANDLING SYSTEMS 21 10.1 General 10.2 Prescriptive Maintenance Requirements 10.3 Performance-Based Maintenance Requirements of Air Handling Systems 21 21 21 11.0 CERTIFICATION 23 12.0 REPORTING OUTBREAKS AND HIGH RISK EVENTS 24 13.0 DECONTAMINATION CLEANING AND DISINFECTION 25 14.0 GUIDANCE 27 Page 3 of 28 August 2012 version 4 1.0 INTRODUCTION Microorganisms are present in almost every environment found on earth including within buildings. Microorganisms are normally present in relatively low concentrations within buildings and are found on surfaces and on airborne dust and aerosol particles. The primary purpose of this Defence policy is to: Assist in the control of microorganisms in systems provided for Defence buildings which are associated with health hazards such as the bacterial genus Legionella. This bacterial genus can cause infections which lead to Legionnaires' disease, hypersensitivity pneumonitis, humidifier fever and Pontiac fever. Assist in the control of other heterotrophic microorganism sources which can lead to health hazards, such as Pseudomonas (e.g. causing skin rashes or ear infections), amoebic meningitis, herpes, Chlamydia and gastro-intestinal infections. Reinforce and support Defence’s commitment to compliance with its obligations under Work Health and Safety (WHS) legislation. 1.1 Aim This policy aims to assist achieving Defence’s objectives and principles by providing general and specific guidance on microbial control in air-handling and water systems of Defence buildings. 1.2 Sponsor This document is sponsored by Directorate of Estate Engineering Policy (DEEP) on behalf of the Technical Authority Assistant Secretary Environment and Engineering (ASEE). Enquiries may be directed to: Director Estate Engineering Policy Brindabella Park (BP-2-B049), Canberra ACT 2600 Tel: (02) 6266 8178 Fax: (02) 6266 8211 Email: DSG - ID Engineering Policy @defence.gov.au Page 4 of 28 August 2012 version 4 2.0 POLICY OBJECTIVES AND PRINCIPLES 2.1 Policy Objectives This policy provides general and specific guidance on matters which shall be considered by Service Providers in relation to microbial control in air-handling and water systems provided for Defence buildings, to assist Defence achieve its compliance objectives. 2.2 Policy Principles The principles described in this document shall be used in implementing the policy objectives. Page 5 of 28 August 2012 version 4 3.0 APPLICATION The policy described in this document shall apply to Defence buildings which include: Cooling water systems as described in SAA/SNZ HB32 and defined in AS/NZS 3666.1:2011. Air-handling systems in buildings excluding refrigerated room airconditioners. Condensate drainage equipment and air filters for non-ducted split system airconditioners. Air conditioning plant. Evaporative cooling, evaporative condenser and closed-circuit cooling systems. Humidifying systems. Water storage systems associated with potable water, fire sprinkler systems, and irrigation. Hot, warm and cold water supply systems. Heated pools, spa pools and hydrotherapy pools. Cooling water systems for refrigeration equipment and air compressors, industrial heat exchangers, spray irrigation systems, industrial type fluid cooling systems. The sources of legionellae which have generally been implicated in worldwide outbreaks of Legionnaires’ disease have been identified with air conditioning systems and cooling water systems which have been incorrectly commissioned or inadequately maintained. Consequently, Defence Estate Management, Defence personnel and Defence Service Providers shall be aware of their responsibilities and duty of care obligations associated with design, supply, installation, commissioning, operation, cleaning and maintenance of air-handling and water systems in order to eliminate the health risk associated with microorganism infections. This policy and related standards apply to all existing, new and replacement Defence plant. The policy shall be read in conjunction with: DEQMS Work Health and Safety. Commonwealth legislation. Relevant State and Territory legislation. Regulatory authority requirements. The term ‘buildings’ as used in this policy in phrases such as ‘air-handling and water systems of buildings’ shall be read as also applying to Defence facilities and installations other than buildings where air-handling and water systems are installed independently of buildings. Such applications may be part of Defence industrial, process, testing or similar applications. For the purpose of this Defence policy: ‘Shall’ indicates a mandatory policy statement. ‘Should’ indicates a policy recommendation. ‘May’ indicates a course of action that is permissible; and the existence of an option. Page 6 of 28 August 2012 version 4 4.0 STANDARDS GUIDELINES AND CODES OF PRACTICE 4.1 Standards Codes Regulations and Legislation Microbial management and control for Defence buildings shall comply with all applicable standards, codes, regulations and legislation including but not limited to the following. The Work Health and Safety (WHS) Act 2011. WHS Regulations and WHS Safety Codes of Practice. National Construction Code (NCC) Volume One – Building Code of Australia (BCA). AS 1657:1992 Fixed platforms, walkways, stairways and ladders – Design, construction and installation. AS 1668.2-1991 The use of mechanical ventilation and air-conditioning in buildings. Mechanical ventilation for acceptable indoor-air quality. AS/NZS 1715:2009 Selection, use and maintenance of respiratory protective devices. AS/NZS 1716:2012 Respiratory protective devices. AS 2610.1-2007 Spa pools – Public spas. AS/NZS 2865:2009 Confined spaces. AS 3498 - 2009 Authorization requirements for plumbing products - Water heaters and hot-water storage tanks. AS/NZS 3666:2011 Air-handling and water systems of buildings - Microbial control. Part 1: Design, installation and commissioning. Part 2: Operation and maintenance. Part 3: Performance-based maintenance of cooling water systems. Part 4: Performance-based maintenance of air-handling systems (ducts and components). AS/NZS 3500 Plumbing and drainage. Part 1: Water services. Part 4: Heated water services. AS/NZS 3896:2008. Waters—Examination for Legionella spp. including Legionella pneumophila. AS 3979-2006 Hydrotherapy pools. AS/NZS 4276 Water microbiology. State and Territory statutory laws and related codes of practice and guidelines. 4.2 Guidelines and Application Manuals The following documents provide relevant guidance. Defence Safety Manual (SAFETYMAN). Defence Incident Report Form AC 563. To be used in the event of an incident or accident and available through DEQMS Support, OH&S, Forms. SAA HB9 - 1994, Handbook – Occupational personal protection. SAA/SNZ HB32:1995 Control of microbial growth in air-handling and water systems in buildings. National Environmental Health Forum Monographs. Water Series No. 1. Guidance for the control of Legionella. 1996. Page 7 of 28 August 2012 version 4 AIRAH Application Manuals. DA17 – Cooling Towers. DA18 – Water Treatment. DA 19 HVAC&R Maintenance, DA26 – Indoor Air Quality. ASHRAE Handbook – HVAC Applications. Chapter: Water Treatment. AIRAH Best Practice Guidelines – HVAC Hygiene. Guidance material provided by Comcare. Guidance and mandatory requirements of safety data sheets provided for water treatment chemicals and biocides. ASHRAE Guideline 12-2000. Minimizing the Risk of Legionellosis Associated with Building Water Systems. ANSI/ASHRAE Standard 188P: Prevention of legionellosis associated with building water systems. Page 8 of 28 August 2012 version 4 5.0 DEFINITIONS For the purpose of this policy the following definitions apply. Automatic Bleed-Off Equipment Equipment which removes water from a system to limit the concentration of total dissolved solid and suspended solids. Automatic Dosing Equipment Equipment which automatically doses cooling water systems with biocides and water treatment chemicals to control microbial growth, corrosion, scaling, fouling and the build-up of solids. Biofilm A layer of microorganisms formed as a thin slime on surfaces in contact with water. Cooling Water System A heat exchange system comprising heat-generating plant, water-based heat rejection plant and interconnecting recirculating pipework and associated pumps, valves and controls. Cycles of Concentration The degree of concentration of the dissolved solids of the cooling system make-up water as a result of the evaporation that takes place in the cooling tower. Dead-leg A section of a water-based system that does not permit the circulation of water. Drift Water lost from a cooling tower, evaporative condenser or similar equipment as liquid droplets entrained in the discharge air. This excludes condensation. Drift Eliminators Inertial moisture droplet stripping devices fitted to cooling towers and evaporative condensers to remove moisture droplets entrained in the discharge air. Evaporative Air-Cooling Equipment A device that effects a reduction of the dry bulb temperature of air by evaporating water into air. Evaporative Condenser A heat exchanger in which refrigerant is cooled by a combination of air movement and water spraying. Heterotrophic Microorganisms Microorganisms that obtain nourishment by digesting plant or animal matter, as opposed to photosynthesizing food, as plants do. High Risk Event An event that could reasonably be expected to significantly or adversely affect public health. Humidifier Fever Page 9 of 28 August 2012 version 4 A form of allergic reaction caused by inhalation of allergens of microbial origin arising from the wetted surface of equipment, such as humidifiers. Hypersensitivity Pneumonitis Respiratory illness usually caused by inhalation of the spores or antigens of various different types of microorganisms. Key Performance Indicator A risk factor that is identified as testable, assessable and controllable for the performance, monitoring and verification of the system. Legionnaires’ Disease A potentially fatal illness characterised by pneumonia and cause by infection with Legionella bacteria species, commonly L.pneumophila. All infections caused by Legionella species are covered by the general term ‘legionellosis.’ (Legionnaires disease is a notifiable disease in each State and Territory). Pontiac Fever A self-limiting, short-duration, non-fatal fever caused by Legionella bacteria. Regulatory Authority Any authority that is authorised by statute to exercise jurisdiction over matters such as the design, materials, installation, commissioning, operation or maintenance of any part of an air-handling or water system, plant, equipment or systems covered by this policy. Significant Modification A modification to a warm water or air handling system falling within the meaning of AS/NZS 3666 that directly affects the hazard potential of the equipment. Page 10 of 28 August 2012 version 4 6.0 LEGIONELLA BACTERIA Legionella bacteria are widespread in nature and can be found in a variety of environments including most fresh water, natural and constructed water sources, fresh or brackish water, coastal waters, mud and soil, in potting mixes and in compost. Consequently, it is to be expected that Legionella bacteria will be present in building air-handling and water systems. Legionella thrives in particular environments, which are outlined below: In warm water Legionella bacteria: Remain dormant at low temperature and growth below 25ºC is rare. Multiply in the temperature range of 20ºC to 45ºC with the optimum range being 35ºC to 37ºC. Growth ceases above 45ºC and the bacteria dies with increasing rapidity as temperature rises above 45ºC. Are killed by long exposure at 50ºC temperature and by shorter exposure at higher temperatures. Are killed almost instantly at 70ºC. The presence of sediment, sludge, scale and organic material act as nutrient sources and provide a surface for attachment. Some materials, such as natural rubber used for tap washers, are a known nutrient source. Care is required in their use and application. Presence of waterborne microorganisms, such as algae, amoebae and other bacteria can provide nutrient sources. Algal slimes provide a stable environment for growth. The bulk of the microbial population in any water system is present in the biofilms which cover all wetted surfaces. On these surfaces, traces of nutrient are absorbed and aggregate and thereby sustain those passing microbes which settle and adhere to them. A biofilm is built up comprising a mixed population of interdependent microbial species embedded in a matrix which supports and protects them. Legionella has been shown to be a biofilm organism and thrives in biofilm. Consequently, biofilm formation can protect legionellae from concentrations of biocide that would otherwise kill or inhibit growth. Dead legs in piping systems (i.e. sections of the system that do not allow water circulation) provide niches for growth. Temperature stratification in calorifiers can provide locations suited to legionellae growth. The growth of the bacteria is very responsive to the presence of iron and zinc such as occurs in unprotected, rusting galvanised iron construction material in wet cooling tower environments. The presence of oxygen and carbon dioxide. In their natural environments legionellae obtain their requirements for growth and proliferation (i.e. cell division) through interactions with other microorganisms such as algae, protozoa and other bacteria, and by the utilisation of organic and inorganic material. Legionellae are parasitic and can infect freshwater amoebae and multiply within them. The persistence of legionellae within amoebae provides a means for dispersal and survival in ambient air conditions which would normally kill them. Amoebae can also protect parasitic legionellae from disinfection. Page 11 of 28 August 2012 version 4 Legionellae also proliferate within biofilms, within other microorganisms and their byproducts and within matter entrained in water systems. Design, installation, operation and maintenance of air-handling and water systems for Defence buildings shall consider the above matters when establishing appropriate control measures against microbial growth including Legionella bacteria. New and replacement equipment and systems shall be selected, designed, manufactured, installed and operated on the basis of eliminating environments which are susceptible to the uncontrolled growth and proliferation of Legionella bacteria. Consideration shall be given to associated factors such as the location of the equipment and systems, construction materials, and maintenance requirements including provisions for cleaning and water quality monitoring. Page 12 of 28 August 2012 version 4 7.0 MICROORGANISM MANAGEMENT AND CONTROL Defence Manager Estate and Facilities Services (MEFS) shall ensure that Service Providers responsible for the maintenance of air-handling and warm water systems develop and keep current, compliant plans for the management and control of microorganisms in the maintained systems. Plans shall include appropriate maintenance and operation instructions that are to be recorded in the Garrison and Estate Management System (GEMS). Maintenance Service Providers shall ensure management and control of microbial growth are in full compliance with the requirements of regulatory authorities, State and Territory Health Departments, and local municipal authorities. Maintenance and operating instructions shall as a minimum comply with the requirements of: The above authorities. The applicable requirements of the Standards and documents covered under clause 4.0. Maintenance instructions shall include mandatory procedures for the use of personal protective equipment, for handling of chemicals and for working in confined spaces. Microorganism management and control shall allow for the possible development of microbial resistance to specific biocides and biocide formulations. Service Providers shall regularly alternate biocides to reduce the risk of resistant strains of microorganisms being developed. Care shall be taken in the use of biocides, cleaning agents and any other chemicals in air-handling equipment such as humidifiers, spray coils and evaporative air cooling equipment. Chemicals may be hazardous to health when entrained in the airstream. Suppliers’ recommendations, including safety data sheets and other information shall be followed to ensure the proper use of chemicals. Page 13 of 28 August 2012 version 4 8.0 COOLING WATER SYSTEMS 8.1 Approach to Maintenance The biological process of rapid growth of Legionella bacteria in water systems to high concentrations is essential before the water systems are considered potentially hazardous and capable of causing the serious and potentially fatal illness legionellosis. Consequently, effective control of the growth process is fundamental to addressing the potential hazard and this is achieved by effective maintenance and compliance with applicable legislation, codes, standards and regulatory authority requirements. The design of water systems shall facilitate maintenance, cleaning, control of microbial growth, and minimising drift from the heat rejection plant. This shall be achieved by compliance with the applicable requirements of Clause 4 Standards, Guidelines and Codes of Practice. Parts 2, 3 and 4 of AS/NZS 3666:2011 include prescriptive and performance-based approaches to maintenance of air-handling and water systems of buildings. Defence presently requires a prescriptive-based approach to maintenance of cooling water systems where the maintenance actions are prescribed and in accordance with AS/NZS 3666.2:2011. However, in some situations a performance-based approach may be necessary for reasons described under 8.3 below. Where a performancebased approach is required for a specific Defence system AS/NZS 3666.3:2011 shall apply and associated water quality management and testing regimes shall be in place and strictly followed. Under the performance-based approach Defence relies upon the expertise of Service Providers to assess and recommend the most appropriate approach to maintenance for a particular application based on their professional experience and technical competence. Irrespective of the prescriptive or performance-based approach to maintenance, in the event of an outbreak of Legionnaires’ Disease or water sampling results that identify actionable microorganism quantities (for legionellae or heterotrophic microorganisms as determined by AS/NZS 3666.3:2011 Tables 3.1, 3.2) immediate notification to Defence is required together with special action as determined by the Standard and as advised by the local health authorities. 8.2 Prescriptive Maintenance Requirements Section 2 of AS/NZS 3666.2:2011 covers a prescriptive approach to operation and maintenance of air-handling and water systems of buildings. Clause 2.5 describes a prescriptive approach to maintenance of cooling water systems. Typically, Service Providers should follow this approach where systems can be shut down without adversely affecting Defence capability, continuity of service or process, or the Defence facility being served. The prescriptive maintenance requirements of AS/NZS 3666.2:2011 Section 2 includes minimum inspection and cleaning periods which in the case of cooling water systems is inspection at least monthly and cleaning as necessary with intervals not exceeding six months. For evaporative coolers the Standard’s inspection requirement is at least every three months. However, regular cleaning and draining is considered to be the most appropriate means of microbial control for evaporative coolers and industry Page 14 of 28 August 2012 version 4 experience has shown that a frequency of three-monthly cleaning is inadequate in some Australian localities and some applications. Consequently, local conditions such as excessive dust, construction activities, excessive ambient conditions and the like, may necessitate a shorter maintenance frequency. In exceptional situations such as dusty and windy conditions this frequency may need to be weekly. Service providers shall fully consider the local site conditions and ambient weather when determining and recommending maintenance frequencies. Maintenance frequencies shall be reviewed for effectiveness by the Service Provider on an ongoing basis during the maintenance period and shall be adjusted to more frequent maintenance if determined necessary by maintenance experience. All such adjustments shall be in full consultation with Defence. In no circumstances shall maintenance be reduced to less frequent maintenance than stated in AS/NZS 3666.2:2011. 8.3 Performance-Based Maintenance Requirements The prescriptive approach to maintenance of water systems described in AS/NZS 3666.2:2011 is not appropriate for critical Defence systems which cannot be shut down for regular cleaning. In this situation Service Providers shall follow the performance-based maintenance approach in accordance with AS/NZS 3666.3:2011 for cooling water systems. The primary aim of this approach is preventive by nature, i.e. to avoid conditions occurring in cooling water systems which may allow microorganisms including legionellae to multiply and thereby cause a health risk. This is achieved by: effective, methodical management of a system’s water quality which includes monthly cooling water sampling and assessment for the presence of legionellae, creating hygienic conditions, and automatically regulating water treatment and monitoring, assessment and control strategies. Health is a principle outcome of the performance-based approach. Risk assessments for Defence cooling water systems shall be undertaken every five years or as otherwise directed by the MEFS. Assessments shall be carried out by practicing engineers in accordance with AS/NZS 3666.3:2011 Clause 2.3 Risk Assessment. (Defence requirements for a ‘practicing engineer’ are stated under clause 11.0 Certification). Risk assessments shall include a determination of the criticality of the Defence system whereby a critical cooling water system is one which cannot be shut down for regular cleaning due to Defence capability, continuity of service, security or similar considerations. Existing risk assessments shall be revised if: There are reasons to believe that the findings of the original assessment are no longer valid; System monitoring reveals the need for preventive or corrective action; Significant change has occurred in the local environment, in local work practices or in equipment; Construction work is proposed, or has commenced in the vicinity of the cooling water system. Page 15 of 28 August 2012 version 4 Copies of the risk assessment report shall be submitted to the MEFS, to the regulatory authority, and to Comcare (upon request). A copy of the risk assessment report shall be incorporated into the Operation and Maintenance (O&M) manual, the site water treatment manual and GEMS. AS/NZS 3666.3:2011 Table 2.1 ‘Risk Factors to be Assessed and Controlled’ shall be assessed and documented for each individual system (i.e. for each cooling water system rather than each overall Defence facility). Key performance indicators identified in Table 2.1 shall be monitored and controlled in accordance with AS/NZS 3666.3:2011 Section 3 ‘Performance monitoring and control. AS/NZS 3666.3:2011 Table 3.1 describes the required control strategies for the presence of legionellae whilst Figure 3.1 describes the associated assessment and control process. Similarly, Table 3.2 describes the required control strategies for the presence of other heterotrophic microorganisms whilst Figure 3.2 describes the associated assessment and control process. These control strategies and assessment and control processes shall be followed when using the performance based approach to maintenance. If in doing so, additional operation and maintenance requirements are identified, they shall be included in the maintenance Service Provider’s management and control plans in consultation with Defence. The initial risk assessment of a cooling water system shall be carried out as part of the implementation of the Standard to the installation or as required by the regulatory authority. For a new installation, initial risk assessment shall commence during the design stage and be reviewed during initial operation of the completed installation. The risk assessment reports and control measures shall be recorded in the project records and incorporated into the Operation and Maintenance (O&M) manual, the site water treatment manual and GEMS. The management of system water quality is an important strategy in minimising health risks associated with cooling water systems. Automatically regulated water treatment systems shall be provided for cooling water systems for effective management of corrosion, scaling, fouling and microbial growth. The effectiveness of water quality management systems and water treatment shall be assessed by the Service provider in accordance with ASNZS 3666.3:2011 Clause 3.4. Assessment frequency shall be at least monthly when the cooling water systems are in use. The temperature of the operating cooling water systems shall be monitored and assessed in accordance with AS/NZS 3666.3:2011 Clause 3.5 Water Temperature. Assessment frequency shall be at least monthly when the cooling water systems are in use. AS/NZS 3666 advises that the available data for outbreaks of legionellae infections indicate that most outbreaks are associated with a concentration of 1,000 cfu/mL (colony forming units per millilitre) or greater and that disease may be associated with lower levels. Consequently, the intent of AS/NZS 3666 is for cooling water systems to operate with non-detectable concentrations of legionellae. Under the performance-based maintenance approach examination for the presence of legionellae shall be carried out monthly in accordance with AS/NZS 3896:2008 by a NATA accredited laboratory. A control strategy shall be immediately initiated in accordance with AS/NZS 3666.3:2011 Clause 3.2 whenever a detectable concentration of Legionella is found, where ‘detectable’ is defined as 10 cfu/mL or greater. Where higher concentrations are detected, a more demanding control strategy is required, as determined by Table 3.1 AS/NZS 3666.3:2011. Page 16 of 28 August 2012 version 4 Similarly, under the performance-based maintenance approach examination for the presence of heterotrophic microorganisms shall be carried out monthly by a NATA accredited laboratory in accordance with AS/NZS 3666.3:2011 and AS/NZS 4276.3.1:2007 or AS/NZS 4276.3.2:2003 as applicable. A control strategy shall be immediately initiated in accordance with AS/NZS 3666.3:2011 Clause 3.3 and Table 3.2 whenever a heterotrophic colony count (HCC) is ≥100,000 cfu/mL. 8.4 Existing Equipment Upgrade The following cooling water system equipment shall be upgraded without delay if identified as non-compliant with the relevant requirements of the standards, codes, regulations and legislation identified in Clause 4.1. The completed upgrade shall be certified by a practicing engineer. (Refer to clause 11.0 Certification) Drift eliminators. These are a vital piece of equipment for minimising the risk of Legionnaires’ disease outbreaks due to cooling water systems. They also help to retain the chemically treated water in the systems. For specific requirements refer to AS/NZS 3666.1:2011 Clause 4.4 Drift Control and to the regulatory authority. Upgrades to eliminators may increase air flow resistance through the cooling plant and thereby reduce the heat rejection capacity. Consequently, Service Providers shall assess the impact on system performance and heat rejection capacity and shall advise Defence accordingly before the replacement is undertaken. Automatic cooling water bleed-off equipment. Automatic cooling water chemical and biocide dosing equipment. 8.5 Intermittent and Seasonal Equipment Use Where a cooling water system has been out of operation for a period of more than 30 days an assessment shall be carried out in accordance with AS/NZS 3666.3:2011 3.6 Start Up. This requires the actions of clauses 3.2 to 3.5 of the standard to be carried out within 3 to 7 days of the system recommencing operation. Where a cooling water system is shut down without being drained, the water treatment program shall be maintained until the system is returned to normal use. AS/NZS 3666.2:2011 clause 2.5.4 requires cooling water to be circulated through the entire system at intervals of not greater than once every 48 hours. This is a maximum interval which Defence requires to be appropriately reduced to circulate corrosion inhibitors and biocides where the local environment, local work practices or adjacent construction activities adversely affect the cooling water system or encourage microbial growth. A cooling water system that is typically on stand-by or used as a back-up system shall be operated for a minimum period of one hour per week to circulate corrosion inhibitors and biocides. The minimum one hour period may need to be increased by Service Providers in situations where the local environment, local work practices or adjacent construction activities adversely affect the cooling water system or encourage microbial growth. 8.6 Start-Up and Shut-Down Instructions All Defence cooling towers, evaporative condensers and similar cooling water equipment shall have written start-up and shut-down instructions prominently displayed on or near to the plant. The instructions shall be clear, concise, and simple Page 17 of 28 August 2012 version 4 to follow and shall be protected from weathering. The instructions shall include full (normal and emergency) contact details of: The maintenance Service Provider. The water treatment Service Provider. The regulatory authority with jurisdiction over the installation. The building owner or owner’s representative. 8.7 Retention of Records All records of cooling water system treatment, inspections, maintenance and testing shall be prepared, retained and made readily available for inspection in accordance with Defence requirements and those of regulatory authorities and AS/NZS 3666.3:2011 Clause 3.7 Results and Records. The records provide evidence of compliance and as such shall be retained in a legible form for a minimum period of 7 years. Page 18 of 28 August 2012 version 4 9.0 WATER SYSTEMS 9.1 General For the purposes of this policy document hot and warm water are defined in accordance with AS/NZS 3666.1:2011 as follows: Hot water is water at or above 60ºC. Warm water is water between 30ºC and 60ºC (nominally 43ºC). Hot, warm and cold water systems shall be designed to avoid conditions likely to encourage the growth of legionellae. In addition to complying with the relevant requirements of the standards, codes, regulations and legislation identified in Clause 4.1, the guidance provided in the document ‘Guidance for the control of Legionella – National Environmental Health Forum Monographs – Water series no. 1’ shall be considered by Service Providers. 9.2 Water Treatment Products Defence requires water treatment product literature and safety data sheets (SDSs) to be included in the building’s water treatment service manual, the O&M manual, and to be readily available on site to anyone who could be exposed to the product. SDSs shall comply with Work Health and Safety Regulations 2011: Chapter 7. Hazardous chemical. Part 7.1 Hazardous chemicals. Division 2 Obligations relating to safety data sheets and other matters. Schedule 7 Safety Data Sheets. The relevant information, requirements and instructions in the SDSs shall be followed whenever the water treatment product is being handled, stored, used and disposed of. All water treatment products used and their labelling, packaging, storage and user instructions shall comply with all applicable legislation and regulatory authority requirements. Appropriate safety signs shall be permanently exhibited in Defence building locations where hazardous water treatment products (i.e. chemicals, biocides and other similar toxic materials) are handled, stored, used and disposed of. Safety signage shall comply with AS 1319-1994 ‘Safety signs for the occupational environment’ and, where necessary, the ‘Globally Harmonised System for the Classification and Labelling of Chemicals’ (GHS). Evidence of compliance with Defence policy together with authorisation or certification by the relevant regulatory authority shall be included in the water treatment service manual and the site O&M manual. The evidence shall confirm that the water treatment products, when used in the full range of required concentrations and combinations for effective treatment, comply with the relevant regulations which restrict hazardous effluents in the air and waste water drainage systems. Where a system’s cooling water is drawn from a source other than cold water mains (i.e. a lake, cooling pond or where grey water is use), alternative water treatment considerations and strategies will be involved. These shall be documented and applied based on past experience and relevant information. Page 19 of 28 August 2012 version 4 9.3 Proprietary Water Treatment Devices Conventional treatment of cooling water systems achieves microbial control through the use of biocides and water treatment chemicals. Proprietary devices of a nonchemical type are available to the HVAC industry as an alternative to conventional water treatment. However, these should not be used without substantiation of their claimed effectiveness and a thorough understanding of the technical aspects of the processes involved. Two of the common non-chemical water treatment alternatives are: Metallic Ions This alternative releases silver or copper ions into the cooling water via electrochemical means to control bacterial growth. Some chemical water treatment is still required for the treatment to be effective. Major concerns with this alternative are: The potential for copper ion deposition on steel and aluminium surfaces within the cooling water system and subsequent galvanic corrosion. Limitations placed by water treatment authorities on the discharge of cooling water systems containing copper and silver ions. Ultraviolet Irradiation This alternative process involves killing microbes in the circulating cooling water by exposing them to ultraviolet radiation. However, this is not effective for cooling water systems where all of the microorganisms cannot be exposed to the treatment. This situation arises because: The ultraviolet irradiation process leaves no residual material in the water to kill microbes which are remote from the ultraviolet light source. Sessile microbes (i.e. microbes that are permanently attached to the internal surfaces of the cooling water system rather than floating in the water) and microbes that do not pass the ultraviolet light source are not affected by the process. Effective water treatment systems must be able to control biofilms which attach around the internal surfaces of the complete water circuit, remote from the ultraviolet light source. Any form of water treatment for Defence buildings shall be tried and tested and proven effective rather than relying on unsubstantiated claims by manufacturers and suppliers. (Substantiation requires independent laboratory and field trial testing plus verification with credible supporting evidence). Proprietary water treatment devices and systems shall not to be used for Defence buildings unless proven effective by credible evidence which is submitted to DEEP for review and assessment prior to installation. Page 20 of 28 August 2012 version 4 10.0 AIR HANDLING SYSTEMS 10.1 General Guidance on the control of microbial growth in air-handling systems is provided in the following: SAA/SNZ HB32:1995 Control of microbial growth in air-handling and water systems of buildings AIRAH Application Manual No. DA26 – Indoor Air Quality. AS/NZS 3666:2011 Parts 2 and 4. These standards cover prescriptive and performance-based maintenance approaches for air-handling systems of buildings which are also aimed at controlling microbial growth. Defence relies upon the expertise of Service Providers to assess and recommend the most appropriate approach to maintenance for a particular application based on their professional experience and technical competence. Air-handling system filters: Attention is drawn to the requirements of AS/NZS 3666.1:2011 Clause 2.4 with regards to air handling system filters having a minimum 20% efficiency when tested with test dust No. 1 and a minimum 85% arrestance when tested with test dust No. 4, in accordance with AS 1324.2. 10.2 Prescriptive Maintenance Requirements AS/NZS 3666.2:2011 Clause 2.3 describes prescriptive maintenance requirements for air-handling systems. Equipment covered includes: Outdoor air intakes and exhausts. Air filters. Humidifiers. Evaporative air-cooling equipment. Ducts and components, the latter including coils, trays and sumps, condensate drains, fans, terminal units, supply air outlets, return and relief air grilles. 10.3 Performance-Based Maintenance Requirements of Air Handling Systems AS/NZS 3666.4:2011 addresses the performance of maintenance programs and is required to be read in conjunction with AS/NZS 3666.1:2011, and the relevant clauses of AS/NZS 3666.2:2011. The objective of the standard is to provide a performance-based approach to the maintenance of hygienic conditions with airhandling systems of buildings. AS/NZS 3666.4:2011 covers a performance-based risk management methodology for maintenance. This verifies control of contamination sources to ensure air-handling systems provide acceptable air quality and meet the same level of maintenance described by the prescriptive requirements of the standard. Whilst performance based maintenance of air-handling systems in Defence buildings shall generally be carried out to the requirements of AS/NZS 3666.4:2011, Service Providers shall incorporate the WHS Act’s approach to risk elimination into the methodology described in the standard. Page 21 of 28 August 2012 version 4 AS/NZS 3666.4:2011 describes microbial monitoring, assessment and control strategies in terms of key performance indicators which are carried out in accordance with the Standard’s Table 2.1 ‘Risk Factors to be Assessed and Controlled.’ Section 2 of this Part of the standard ‘Identification and Assessment of Risk Factors’ lists risk factors that contribute to the growth and dissemination of microorganisms within air-handling systems and clause 2.3 describes a risk assessment method to be undertaken. Appendix A of this Part of the standard covers ‘Risk Characterization’ which sets out a procedure for tabulating the assessments for each identified risk category. Risk characterization includes the following key concepts as described in the standard. ‘Likelihood Assessing the likelihood of an identified problem becoming worse than before the next planned maintenance visit, rated from ‘insignificant’ to ‘catastrophic.’ Consequence The significance of adverse conditions or events, rated from ‘almost certain’ to ‘rare.’ Inherent risk level A qualitative assessment of the risk as a result of determinations of consequence and likelihood, rated from ‘low’ to ‘extreme.’ Control mechanism A fortuitous or planned means of controlling or reducing the risk. Residual Risk The final outcome for each risk category.’ The approach described above is based on the concept of risk characterization and risk reduction to a target residual level. It is important for Defence Service Providers to apply the WHS Act’s due diligence approach to performance based maintenance which first and foremost aims to eliminate risk rather than minimising it to a target residual risk. Where the risk assessment process for performance-based maintenance does not eliminate an identified risk, it is important to document the justification for elimination not being achieved and the considerations of the other control methods in order of the hierarchy. Page 22 of 28 August 2012 version 4 11.0 CERTIFICATION Practicing engineers shall certify to Defence, compliance of the microbial control provisions of all new or modified existing air-handling and water systems provided for Defence buildings, with the requirements of AS/NZS 3666:2011 and other applicable Codes and Standards. Copies of the written certification shall be submitted to the Project Director, the MEFS, the regulatory authority and to GEMS. Copies may be provided to Comcare upon request. A copy shall be provided in the O&M manual and the water treatment manual. For the purpose of this policy document, a practicing engineer is one registered with the National Professional Engineers Register (NPER) and registered to practice in the areas of Mechanical Engineering or Building Services Engineering. In addition, Defence requires such engineers to have the qualifications and experience to evaluate the condition of the complete cooling water system. They shall be competent, practicing, appropriately qualified and appropriately experienced. Page 23 of 28 August 2012 version 4 12.0 REPORTING OUTBREAKS AND HIGH RISK EVENTS Legionellosis is a reportable disease under State and Territory Health Acts. MEFS shall ensure their maintenance Service Providers, Project Managers, Contract Managers and the like who are responsible for the installation and maintenance of air-handling and water systems are aware of their legal obligations for reporting high risk microbial events. Maintenance Service Providers, Project Managers, Contract Managers and the like shall inform themselves of their statutory obligations for reportable, communicable diseases such as legionellosis, Pseudomonas, amoebic meningitis, gastro-intestinal infections etc. The MEFS shall notify the State or Territory Health Department, regulatory authority and Comcare within 24 hours of: receiving a test result of Legionella bacteria concentration ≥ 1,000 cfu/mL; or after receiving a test result of heterotrophic colony count ≥ 5,000,000 cfu/mL; or any other high risk event; or as otherwise required by State of Territory Health Departments or the regulatory authority; and confirm and enact the required measures to prevent an outbreak of illness. The above events are classified by Defence as dangerous incidents (i.e. high risk events) and shall be notified in accordance with the procedures in the Defence WHS Incident Report AC563. Defence MEFS shall keep their WHS representatives informed of all microbial testing results (including low and high risk events) and all measures taken to assure that airhandling and water systems are well maintained and operating in a safe, hygienic and compliant condition. In the event of high risk events they shall fully inform their WHS representatives about actions taken to eliminating the risk, and provide full details of subsequent test results. Page 24 of 28 August 2012 version 4 13.0 DECONTAMINATION CLEANING AND DISINFECTION It is not the intent of this policy to detail procedures for decontaminating, cleaning and disinfecting air-handling and water systems. These procedures are adequately covered by existing Standards and expert literature and are also subject to continuing change as knowledge and experience of treatment methodologies grows. It is also recognised that regulatory authorities, State and Territory Health Departments and local municipal authorities, may have their own specific procedures. Guidance on decontamination, cleaning and disinfection is provided by State and Territory Codes of Practice, by local health authorities, and in the following documents: AS/NZS 3666.3:2011 Appendix B. On-line Disinfection Procedure for Cooling Water Systems. AS/NZS 3666.3:2011 Appendix C. Decontamination Procedures for Cooling Water Systems. National Environmental Health Forum Monographs. Water Series No. 1. Guidance for the control of Legionella. 1996. Clause 10.1.4 Cleaning and Disinfection. Clause 10.1.6 Decontamination. ACT Health Code of Practice 2005. Cooling Towers, Evaporative Condensers and Warm Water Storage Systems. Appendix C. Warm water storage system cleaning and disinfection. SAA/SNZ HB32:1995 Control of microbial growth in air-handling and water systems of buildings. Clause 6.12. Decontamination. Guidelines for the use of personal protective equipment during commissioning of cooling water systems are provided in Appendix A of AS/NZS 3666.1:2011. Defence policy requirements are: Decontamination, cleaning and disinfection procedures shall be acceptable to the applicable regulatory authorities. They shall be determined and specified by the design Service Provider during system design; confirmed by the installation Service Provider upon completion of the installation; included in the O&M Manual and the site water treatment service manual; and provided readily available at the site installation for immediate reference. The procedures shall be reviewed annually and maintained current by the maintenance Service Provider. Decontamination, cleaning and disinfection shall be carried out in accordance with the requirements of the applicable regulatory authorities. Appropriate safety precautions shall be taken during decontamination, cleaning and disinfection. Personal protective clothing and equipment shall be used where hazardous chemicals are stored and where used in the decontamination, cleaning and disinfection process. All work shall be carried out by and supervised by appropriately licensed, experienced and competent persons. Emergency decontamination, cleaning and disinfection shall be carried out upon occurrence of a high risk event or when directed by the regulatory authority or by Defence. Appropriate records of all decontamination, cleaning and disinfection events shall be recorded in the site maintenance log book, provided to the MEFS and recorded as otherwise required by the regulatory authority and Defence. Page 25 of 28 August 2012 version 4 All duties, responsibilities and reporting requirements associated with maintenance of air-handling and water systems at Defence buildings shall be clearly defined and diligently carried out. (Outbreaks of legionellosis have occurred in situations where engineering solutions were appropriate but definitions of duties were unclear and reporting procedures were poor). Page 26 of 28 August 2012 version 4 14.0 GUIDANCE General guidance on minimizing the risk of microbial growth in air-handling and water systems is described in this clause for information purposes. The guidance is based on Defence and industry experience and is included in this policy document to reinforce good practice and compliance. The guidance is not intended to be fully comprehensive or to replace the professional expertise and competence required of Defence Service Providers when exercising their due diligence for legislation, code and policy compliant outcomes under their WHS duty of care obligation. Incoming cold water supplies should be protected against heat gains which may inadvertently increase the water temperature to 30ºC or more. Heat gain to reticulated and stored cold water should be avoided. Hot water systems should be of the pressure mains type and thermostatically set to 60ºC or greater. Large central hot water systems with long runs should incorporate recirculating pumps to ensure the temperature of the water in the reticulation systems and storage tanks is maintained above 60ºC. New or extended cold water storage tank systems should be cleaned and disinfected before commissioning, in accordance with AS/NZS 3500.1. New or extended hot water systems should be operated and maintained in accordance with AS/NZS 3500.4. Cooling tower fans and the condenser water pumps should continue to operate for a period after the thermal plant has shut down so that hot condenser water can be cooled to below 25ºC (or preferably below 20ºC) to minimize microbial growth. Cooling tower fans should commence operation before condenser water flows through the tower and should continue to operate for a period of time after shutdown of condenser water flow. This strategy ensures that condenser water is passing through the cooling tower only when the rated air quantity passes through the drift eliminators and thereby minimizes condenser water drift. Where duplicate (duty/standby) condenser water pumps are provided, the installation and controls should automatically change over the duty and standby pumps on a regular basis to avoid stagnant water and microbial growth in the standby pump and associated pipework. High legionellae concentrations are most likely to occur in small cooling water systems rather than large systems due to their high wetted surface area relative to a small water volume. (Wetted surface area affects sediment deposition and biofilm development). Consequently, small cooling water systems may require greater care and attention than larger systems. The multiplication of legionellae occurs preferentially at the warm surfaces of systems such as piping and heat exchangers rather than in the heat rejection plant (i.e. in cooling tower basins) which contain the coldest water in the systems. Water heaters and hot-water storage tanks should comply with AS 3498 2009 Clause 7 Control and Protection sub-clause 7.1 (j) for the means to inhibit the growth of Legionella bacteria in potable water within the waterheating appliances. The following water systems should be maintained, cleaned and inspected as required by the local water authority, AS/NZS 3500.1 and SAA/SNZ HB 32. - All cold water storage and cold water feed tanks and systems associated with potable water systems. Page 27 of 28 August 2012 version 4 - All water storage tanks and systems associated with fire sprinkler systems. - All water storage tanks and systems (including grey water) associated with irrigation systems. Combined storage tanks for potable water and fire services present a risk of cross-contamination and should be avoided in accordance with AS/NZS 3666.1:2011. Condensate and Equipment Drainage: Plant rooms that are air-plenums (i.e. used for air handling system outdoor air supply or part of the return air path) should comply with AS/NZS 3666.1:2011 clause 2.9 including Notes 1, 2 and 3, requiring sealing of associated drains and traps. Cooling water systems provided for Defence buildings should not include dead-legs, as required by AS/NZS 3666.1:2011 clause 4.1.3. Cooling tower balance (equalising) pipes should be designed to prevent formation of dead-legs and to ensure effective water treatment. Mechanical services drawings should clearly show on plan views and elevations, the respective locations of existing and proposed heat rejection plant (evaporative cooling equipment, cooling towers, evaporative condensers etc) and building openings (air intakes, exhaust outlets, natural ventilation openings, lift shaft vents etc). When locating such plant and openings, Service Providers should avoid cross-contamination and should consider the effect of prevailing wind directions, wind effects, multiple roof levels and arrangement of adjacent structures. Regular routine operation and maintenance should be carried out on airhandling and water systems. AS/NZS 3666.2:2011 Section 2 details minimum requirements which for some systems (i.e. coils, trays, drains, tundishes and sumps etc) involves monthly inspection, checking and cleaning. Easy and safe access should be provided for inspection, maintenance and cleaning of plant, equipment and components covered by this policy. The relevant requirements of associated Standards should be complied with including AS 1470, AS 1657, AS/NZS 1892 Parts 1 and 5 and AS/NZS 2865. Access to heat rejection plant (i.e. cooling towers, evaporative condensers etc) should be controlled and limited to those associated with provision, operation and maintenance of the systems. This may necessitate fencing with locked access gates. ‘Authorised Access Only’ signs should be provided. Warning signs should be provided to discourage people from gathering in the vicinity of heat rejection plant. Care should be taken in the use of chemicals (biocides, cleaning agents etc) in air-handling equipment such as evaporative coolers, humidifiers, spray coils and the like where residual chemicals are directly exposed to the airstream and may present a health hazard. Manufacturers’ recommendations, including SDSs shall be followed to ensure the proper use of such chemicals. Automatic dosing equipment should incorporate a lock-out function which prevents biocides and water treatment chemicals from being injected into the cooling water while the automatic bleed-off to drain is operating. Page 28 of 28 August 2012 version 4