WATER SYSTEM HYGIENE AND SAFETY


Case study I will now step you through a case study involving a small Sydney hospital with a recirculating warm water system, where the aforementioned approach resulted in the following actions being implemented: n A Legionella risk management plan (RMP) developed by a general ‘corporate-style’ risk management firm.


n A chlorine dosing unit installed on the warm water system.


n Sampling initiated with an independent party.


Prior to having the risk management plan prepared, the hospital had engaged an independent microbial testing contractor to take samples and analyse for Legionella and the Heterotrophic Colony Count (HCC) of the water distribution system. As there was no formal sampling protocol to follow, this resulted in: n The water sampling technician taking samples from the most easily accessible outlets – as opposed to those identified as a higher risk.


n An inordinate number of samples being taken from basins, that present a relatively low risk of dissemination compared with showers which may produce aerosols (which can be inhaled).


n An unwarranted focus on HCC – which does not present a Legionella health risk per se, and is not stipulated as mandatory. In addition to the testing undertaken by the independent contractor, the Health Department undertook periodic sampling and testing on an unannounced frequency. The hospital was receiving positive Legionella detections at every round of testing by either party.


Disinfection system maintenance The hospital installed a chlorine dosing system purchased through the HVAC water treatment contractor. The unit was provided by a reputable manufacturer, and was being maintained by the hospital’s ‘in-house’ plumber. With reduced staffing levels, and lack of training or support, this meant that the dosing system was often going into fault due to blocked injectors, chemical dosing tanks running empty, ORP probes not calibrated, and dosing pumps losing prime. To keep the system operating, the supplier recommended a new chemical dosing pump be installed, although the existing pump was still operating correctly. This resulted in the purchase of a piece of equipment which was not necessary. Unfortunately, this did not solve the issue that there was no continuous or reliable source of chlorine being dosed to the system. Effectively training staff on how to overcome a loss of prime, or cleaning the injector using a weak acid, may have gone some way to rectifying the loss of disinfection.


Figure 2: A detailed schematic of the water distribution system prepared by HydroChem following a site audit.


The water supplied to the hospital is via


Sydney Water mains delivered to the site boundary before being held in two bulk storage tanks. The RMP contained a photo of the storage tank and a schematic of the plantroom with no legend. There was no critical assessment of the arrangement. Despite attempting to satisfy the


requirements of local regulations, the outcomes for the hospital were poor. That is, the sampling of outlets continued to return both high HCC and adverse Legionella detections. We can break down the simplified process described above to address Legionella risk as a flow chart, shown in Figure 1. When asked to review the current RMP and outcomes at the hospital, we first noticed something very common in the industry. The actual order of actions undertaken did not follow the flowchart. In this instance, the sampling occurred first, followed by the installation of a chlorine dosing unit in response to poor results, and only recently had the RMP been completed. One may describe this approach as putting the ‘cart before the horse’. It is a common occurrence, as facility managers are trying to satisfy all the requirements of the regulations in one fell swoop. At this hospital, the problem was further


compounded by the fact that each action was undertaken in isolation, without strong lines of communication. The proper implementation of the required steps fell through the gaps. The gaps occur at the arrows of the flow chart, and are a result of each party lacking ‘skin in the game’.


Review of the RMP document HydroChem was engaged in March 2022 to review the RMP document competed in October 2021. The remit was to improve the outcomes of testing, being the poor Legionella detection rate. A new RMP


was not commissioned, so HydroChem provided a desktop review of the RMP, as well as a site audit to review the dosing equipment and sampling protocols. The RMP developed by the firm


comprised 30 pages, the first full page being a statement of limitations – the focus of which was acknowledging that the firm was relying on information provided by the client, and that it accepted no liability for completeness. The completion of remedial actions was not verified by the RMP. There were no records of responses to high Legionella or HCC detections prior to retests. The document listed several hazards to


investigate, which are available from the guidance material provided by regulators. However there was very little in actual validation of the current state of each hazard at the hospital. Moreover, most of the recommendations were motherhood statements highlighting that the hazard ought to be reviewed and considered. There was no empirical data


establishing: n The current mains water system supply and water quality.


n The efficacy or maintenance of the chlorine dosing system.


n A suitable sampling protocol. The RMP recommended that suitably qualified contractors be engaged to determine the aforementioned items.


Gap 1: Sampling Protocol HydroChem commenced the review by addressing the generic recommendations of the RMP. A site audit was undertaken, and a detailed schematic of the water distribution system prepared – see Figure 2. Testing of the mains water and storage tanks revealed that there was nil disinfectant being maintained in the storage tanks. Although Sydney Water


February 2024 Health Estate Journal 31


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