Tarn Pure Case Studies
Commercial vehicle wash
Synopsis: A local authority for one of the largest cities in the UK identified significant infection risks at one of its waste depots, where its fleet of dust carts were cleaned using a commercial vehicle wash on a daily basis. This vehicle wash, in common with many modern installations, recycles its water, having removed through separators and filters the debris and soil washed off the trucks.
The problem: The filtered water, in spite of being treated by conventional means, was infected with a wide variety of bacteria. Significant volumes of this water was lost to the environment as aerosol droplets when sprayed over the dust carts, and was a serious infection risk to employees and others, including members of the public, at or near the waste depot.
The solution: TP Technology cleaned the underground sump tank, the reclaim tank and the ready-to-use tank. A Tarn-Pure™ silver/copper ionisation system was installed on the ready-to-use tank. This has ensured that the water used is free from Legionella and other water-borne bacteria. Monthly tests by an approved independent laboratory show that legionella is constantly not detected ,and TVC counts are now rarely over 200.
Conclusion: The increasing use of recycled water in all vehicle and rail carriage washes has high lighted the risk from infected aerosol droplets to employees and the public.
Tarn-Pure continues to be an effective solution to this potential health hazard on one of the most polluted commercial vehicle wash applications for the five years since installation.
Leisure Facilities
International sailing centre
Synopsis: The small and medium Tarn-Pure systems are frequently used in leisure facilities that have considerable variations in water usage. One such system was installed several years ago on the cold water storage tank for an international sailing centre used by both able bodied and physically challenged. This centre has overnight accommodation for up to 48 people.
The problem: Low water usage at particular outlets and the high temperatures over recent summers led to an increase in detected legionella counts and a solution was needed that would be easy to control, simple to retro-fit and would operate equally effectively in periods of high and low usage. The accommodation tended to be used at weekends, with lower use during the week, and some of the specially designed facilities for the less able could be unused for longer periods.
The solution: A Tarn-Pure system was installed on the central cold water storage tank that serviced hot water make-up and distributed cold water. A flushing regime was instituted to ensure that the outlets in empty rooms were regularly opened. Legionella is no longer a problem, which is confirmed by on-going water analysis.
The golf club
The site now regularly tests as “Legionella Not Detected”.
Residential and sheltered Housing
Synopsis: Tarn-Pure systems are installed on many Sheltered Housing Schemes where there are difficulties using high temperature to control the growth of bacteria. One such group in the South East of England now specifies that Tarn-Pure™ is fitted to every new build project. These projects are normally 40 – 60 accommodation units
The problem: The sheltered housing group had identified difficulties in using temperature as a means of controlling and eliminating legionella. In practice, this method had proved to be unsatisfactory on a number of sites, and the risk of scalding required the installation and ongoing maintenance costs of Thermostatic Mixer Valves.
The solution: The installation of Tarn-Pure™ systems has saved considerably on new build costs by eliminating the need for TMVs. Water is stored and distributed at 43oC in complete safety both from a temperature and bacteria perspective. The other benefit that the group has realised is that their maintenance costs at these properties are noticeably lower than at their other sites where Tarn-Pure has not been installed. This is because a lower hot water temperature reduces the amount of calcium scale deposited in the system and the Tarn-Pure maintenance is much less than for the large number of TMVs that have to be regularly checked and serviced.
Hospitals
There are large Tarn-Pure systems installed on numerous NHS hospital sites but just two of these case histories are shown below
A Victorian building
Synopsis: This building complex is based on an old town hospital built in the mid-1800s, and now has 156 beds and serves as a Community and Mental Health Hospital. The water services on site have been added to, removed, modified and are now a mix of new old and very old. The use of temperature as a control mechanism for Legionella was predictably ineffective as the recommended temperatures could not be maintained throughout the site.
The solution: A Tarn-Pure system has been installed on the cold water storage system with a boost unit on the hot water return. This ensures the correct treatment levels are maintained at periods of low water usage (i.e. when fresh treated water from the cold tank is not drawn). Legionella and TVC counts are now under control and the hot water can be reduced as Thermostatic Mixer Valves are removed.
New build hospital
Synopsis: The second hospital is a medical treatment centre in the Midlands that was built in 2005.
The problem: The primary care trust had previously experienced persistent legionella counts on previous new builds, where the thermal regime had failed to control legionella infection, and sought to avoid the problem on this new site. The difficulty of maintaining minimum temperatures of 50°C throughout the hot water system was seen to be a significant challenge, in spite of the design brief. Furthermore, the trust was fully aware of the difficulties and costs associated with keeping TMVs infection-free.
The solution: Tarn-Pure equipment was installed on the cold water storage tanks at the build stage so both hot and cold water supplies are treated. Wherever water is used in the building it is treated with copper and silver ions, ensuring complete disinfection. Subsequent testing has confirmed the efficacy of the Tarn-Pure installation with consistently negative or low counts.
Care Home
Synopsis: The care home, which is owned by a private company, faced a visit from an HSE inspector, and had conducted tests on their hot and cold water system. These tests had shown unacceptable legionella counts, and the care home manager became very concerned to find a solution.
The problem: The care home manager turned to Tarn-Pure for help, on the advice of another care home manager who had had similar problems before installing Tarn-Pure. Tarn-Pure identified several infrequently used spurs as a potential problem, and an inability of the calorifier to deliver water temperatures over 50°C to the farthest outlets.
The solution: On Tarn-Pure’s recommendation. A Tarn-Pure unit was installed on the rising main, and three non-essential spurs were removed. The HSE inspector was satisfied that the management were taking steps to deal with the problem, and subsequent tests showed the hot and cold water systems to be free of infection. The care home has also been able to reduce hot water temperatures and remove all TMVs, making significant energy and maintenance savings. Since the Tarn-Pure equipment is leased, the care home’s overall costs, including the monthly lease payments, have fallen overall
As a result of This installation, the company that owned the care home has subsequently installed Tarn-Pure systems in all their other care homes.
