Part I of this three-part series identified areas and systems in which Legionella can be found. Part II discussed protective and mitigating systems, and provided the pros and cons of each one. Part III will go more into detail of how to apply the chosen system effectively, along with monitoring and recording test data.
Whether you are working on a new building or retrofitting an existing one, the questions are still the same.
Gather information
Legionella a Risk-Based Design will start by addressing a few important questions. The first one is to request a water quality report, which should be on record, and a recent water sample test report.
Next, determine which water systems they have, including equipment (cooling tower, misting systems, water fountains, etc.) and large water storage tank holding four days of emergency water supply. Then review the 21 areas and systems in part one of this series.
The CDC has a simple checklist available for download on its website (bit.do/LEAForm). The checklist is directed more toward a health official visiting the site, but it’s still a good starting point.
Evaluation information: Evaluate the following information to determine the need for a protection and mitigation program:
If you answered yes to any of these questions, you will need to provide a protection and mitigation program.
It is helpful to create a flow chart or diagram of how the systems are piped using all of the data collected. Place it into a diagram or flow chart that allows you to see the entire facility as a whole and identify hot spots (potential sites for Legionella).
Now it’s time to evaluate the water quality report and any distal site sampling results in order to determine the water make-up. These, too, will make it into your flow chart and diagram to help you identify hot spots.
Define risks
Use your flow chart and/or diagram of the entire facility to begin to identify potential risk locations such as the following:
Identify any risks on your chart or diagram with the issue at hand, such as temperature, scale, stagnant water, etc.
Are there any mitigation points of injection or methods in place to assist in mitigation efforts? Although these are not considered a risk point, they will assist in defining a potential risk in how they use these points.
Plan
Planning will require you to work with the facilities’ risk assessment team. This team will usually consist of infection control members, safety officers, a certified industrial hygienist, a microbiologist and maintenance or engineering staff.
You will want to work with this group in order to determine the best possible locations to monitor and mitigate or maintain system water quality.
Monitoring
Monitoring is important, and how you monitor is just as important. Will your monitoring system be manual or automatic or both?
Does the facility use a building management system and have the capability to accept new signals to monitor?
Fixed monitoring located on the top floor of each building for each system riser, and monitored at the central utility plant building management system shall record chlorine (CI2), pH, conductivity, pressure and temperature for cold, hot and hot water returns every six hours.
System chlorine shall be within the EPA maximum’s primary contaminant level goals (MRDLG) of 4.0 mg/l, and secondary containment levels for pH in between 6.5 and 8.5.
Portable monitoring located on each floor below the highest level of each building for each system riser shall record chlorine, pH, conductivity, pressure and temperature for cold, hot and hot water return every three months manually by facility personnel. System chlorine shall be within the EPA’s maximum primary contaminant level goals (MRDLG) of 4.0 mg/l and secondary containment levels for pH in between 6.5 and 8.5. The portable locations consist of identically spaced quick disconnect ports with a bypass valve in between the two ports. Once connected, you will close the bypass valve to allow all of the water to flow through the sensors on the portable unit.
There are two types of portables to use. One is a manual-read unit and the other is an automatic unit. The latter is within a small case and has a wireless transmitter to send information back to the BMS to record automatically. The suitcase unit has two hoses with male adapters to insert into the quick connects.
Water samples should also be taken from the domestic water storage tank outside (if one is on site) or the central utility plant weekly to record the free chlorine residuals entering the CUP.
Sampling and monitoring of chlorine levels will be performed by the facility’s personnel and recorded. Sampling of distal sites quarterly for Legionella and bacteria levels will be completed by a third-party laboratory.
Portable monitoring should be performed monthly by facility personnel. Portable units will be taken to each quick connection location per riser, per floor, per system of each building, and CI2, pH, conductivity, pressure and temperature for cold, hot and hot water return systems will be recorded monthly. Systems should be within the EPA maximum contaminant levels.
The fixed monitoring location will use off-the-shelf-type sensors in a prefabricated device installed on the cold and hot water systems, as well as a bypass allowing you to replace sensors as needed. This device could also send information using a wireless network back to the BMS.
The portable unit can be a prefabricated framed unit that has the same sensors installed. This portable unit will connect to the portable test ports and mitigation ports throughout the lower levels (below the permanent unit on the upper floor). It is recommended to have multiple units-one for hot and one for cold. If Legionella is detected from a distal site, cleaning the portable unit is simple.
The portable units can be used quarterly or monthly in conjunction with distal site sampling to monitor and record systems for accrediting purposes.
Mitigation
In this section are guidelines for the emergency remediation actions if a water sample tests positive for the Legionella bacteria.
1. If a regular water sample test comes back containing one or more colony forming units of Legionella per milliliter (CFU/ml), then the action shall be an immediate disinfection of the positive test site. If more than one test site comes back containing one or more CFU/ml of Legionella bacteria, then the positive locations shall be analyzed. If the positive results are contained to just a particular area of the building, then a local disinfection action should be taken. If the positive locations are sporadic throughout the entire building, then an entire building disinfection action should be considered.
2. The disinfection action for localized areas should be through injection of chlorine of both the cold and hot water piping systems through injection and monitoring ports in the piping systems. An EPA- approved chlorine product should be used for the disinfection action. The level of chlorine injected to a target concentration is 0.5-0.7 mg/l. Once the disinfection has been completed, the area being disinfected shall then be flushed until the chlorine levels are within the safe EPA & NSF drinking water levels.
3. The disinfection action for the entire hot- and cold-water supply shall be through an increased level of chlorine back at the source equipment located in the CUP. The level of chlorine injected to a target concentration is 0.5-0.7 mg/l. Once the disinfection has been completed, the area being disinfected shall then be flushed until the chlorine levels are within the safe EPA & NSF drinking water levels.
Emergency remediation shall follow all state and local health department authority directions. Emergency remediation is triggered by identification of a definite or possible health care-associated Legionella disease and Legionella-positive water results, or the identification of Legionella-positive water results during quarterly routine environmental testing. Emergency remediation shall be by:
1. Chemical eradication (primary) hot- and cold-water system chemical emergency disinfection procedures shall include:
a. Notification of building occupants and facility personnel of the halogen disinfection with concentrations above EPA-allowable drinking water limits.
b. Installation of EPA- registered and labeled drinking water product.
c. Flush all outlets until halogen concentration measures at least 2 mg/L at each outlet.
d. Close all outlets and disinfect with halogen for between 2 to 24 hours.
e. Flush all outlets until halogen concentrations are measured and documented to be within the EPA limits.
2. Thermal eradication (optional) Hot water system thermal eradication procedures shall include:
a. Notification of building occupants and facility personnel of the thermal eradication scalding potential.
b. Maintain water temperatures between 160 F - 170 F during flushing of each system outlet.
c. Flushing shall be for a 30-minute duration per outlet. Aerator shall be removed during flushing.
d. Master mixing valves shall be bypassed during the thermal eradication efforts (if used).
e. Upon completion, return system back to original settings (I.E. bypass valves, temperatures, etc.).
3. Combination of thermal and chemical eradication (optional)
a. Refer to items 1 and 2 above for process.
4. Copper silver ionization is costly up front, but is constantly protecting the entire system (if maintained).
The preferred method would be chlorine or copper silver ionization. When positive legionella <1 org/ml and >1,000 org/ml gram-negative bacteria occurs in a distal sample area, the hot and cold water risers serving the area effected shall have the portable injection system connected to the local injection stations on the floor level of the affected area. CI2 shall be injected into both the hot and cold water for the area affected increasing the CI2 levels to the maximum of 0.8 mg/l. Each distal outlet shall be opened and flow hot and cold water for a duration of one minute. The closest distal site shall be opened first working your way to the furthest distal site. At the end of this injection time frame, the portable injection system shall be removed and returned to normal operating conditions.
If the affected area continues to regrow positive legionella <1 org/ml and >1,000 org/ml gram-negative bacteria, additional steps shall be taken to eradicate.
1. Connect the portable CI2 injection system to the injection station located in the mechanical room that serves the affected risers. This location will allow injection of CI2 into the hot- and cold-water system for the affected risers. Monitor remote areas for 0.8 mg/l and maintain for a one-week time frame. At the end of this time frame, remove portable injector from station and return to normal operating conditions (CI2 0.5 mg/l considered normal level). Continue to sample and monitor distal points for continued contamination.
2. If the area continues to regrow, increase main CI2 in the CUP to 0.8 mg/l for one week. Monitor remote areas for 0.8 mg/l and maintain for a one-week time frame. At the end of this time frame, return unit to normal operating conditions (CI2 0.5 mg/l considered normal level). Continue to sample and monitor distal points for continued contamination.
3. Monitor remote areas for 0.8 mg/l are achieved during this one-week time frame. Use the remote injection stations if required to maintain the 0.8 mg/l for the one-week time frame.
Example
The first example is an existing VA health care facility that requires them to develop and incorporate a Legionella program.
Go through your progressions from beginning to end starting with gathering information then evaluate it. Remember to create a flow chart or better yet a diagram.
Discuss your plan to monitor and for mitigation if needed, and what to record. Since this is the VA you will also want to review the VA Directive 1061 for guidelines.
Develop your plans and report to explain each piece of the system so they fully understand how it operates and how often samples are to be taken and recorded.
Original post: https://www.phcppros.com/articles/6259-legionella-preventionmitigation-part-3
