Attachment 7 - 668-16-110_Feasibility Study_Report .pdf

Feasibility Study

Temperature Control of Legionella in Domestic Systems

Mann-Grandstaff VA Medical Center – Spokane WA

L&S Project Number: 2021-019

VA Project Number: 668-16-110 - MOD 5

July 2021

Contributors:

Steve Solberg – Plumbing Designer

Andrew Peterson – Mechanical Designer

Joel Estelle – EIT-MT, Mechanical Designer

For

William Wilson Architects

1022 SW Salmon St

Suite 350

Portland, Oregon 97205

Feasibility Study – Temperature Control of Legionella – Mann-Grandstaff Project Number 2021-019 – July 2021

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Table of Contents

Introduction

The Effects of Temperature on Legionella Growth

Scope of Work

Identify Unused Branch Lines and Dead Legs

Dead Leg Elimination and Prevention Plan

Water Systems Management Points to Prevent Legionella and Protect from Scald Injury

Continuous Monitoring of Incoming Water

Hot Water Storage at 140 ֯F Minimum

Cold Water Temperature Control – Add Cold Water Chiller

Water Temperature Control – Add Hot/Cold Water Recirculation

Continuous Monitoring

Install Mixing Valves at All Outlets Where End Users Access Water

Thermal Eradication

Point-of-Use Filtration

Filtration Cost-Benefit Analysis

Conclusion

References

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Introduction

The purpose of this study is to determine the feasibility of Legionella mitigation through temperature control of domestic water pipes at the Mann-Grandstaff VA Medical Center located in Spokane, WA, provide a summary of what actions need to be preformed to reduce the risks to patients and employees of contracting Legionella pneumonia, and outline a cost benefit analysis of the systems proposed in this report.

The Effects of Temperature on Legionella Growth

The CDC defines Legionella as follows; “Legionnaires’ disease is a very serious type of pneumonia caused by bacteria called Legionella... In nature, Legionella live in fresh water and rarely cause illness. In man-made settings, Legionella can grow if water is not properly maintained. These man-made water sources become a health problem when small droplets of water that contain the bacteria get into the air and people breathe them in.”

Legionella lives in the biofilm that forms at the surface of domestic pipe, and thrives between the temperature range that potable water is typically supplied at; 68 ֯F – 140 ֯F (20 ֯C – 60 ֯C). Evidence of this can be seen on the following graphs.

FIG. 1: Number of Legionella pneumophila organisms colonizing the surface of copper ( ), polybutylene (●), and PVCc( ) at 20

֯C (68 ֯F), 40 ֯C (104 ֯F), 50 ֯C (122 ֯F), and 60 ֯C (140 ֯F). In all cases, the standard deviation is less than log₁₀ 0.15 of the plotted mean datum points. (1)

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Scope of Work

Scope of work was provided by the VA Hospital in Modification 5 of this project. The following are the goals of this study:

1) Identify unused water branch line and dead-legs

2) Provide a dead-leg elimination and prevention plan. Plan components shall include:

identification of existing dead-legs, dead-leg risk assessment, removal prioritization, removal schedule, and prevention.

3) Provide schematic (single line) diagrams of the site distribution and domestic water systems (hot and cold). Diagrams shall show how water is distributed, circulated, stored, heated and cooled, treated, and monitored. The diagrams shall be accurate representation of existing conditions and focus on main areas of water distribution and processing system(s) and identify any areas in which water is processed differently (e.g., hemodialysis and sterile processing).

4) Identify water system management points for the buildings’ potable water distribution systems, and, based on the schematic diagrams, where monitoring and controls can be implemented to prevent the growth of Legionella and prevent scald injury.

5) Potable water entering each building shall be continuously monitored for incoming water pressure and the following characteristics: temperature, pH, dissolved solids, and oxidant residual.

6) If a building uses domestic hot water storage tanks, water temperature of all such storage tanks shall be maintained at a minimum of 140 degrees Fahrenheit ( ֯F). The minimum discharge temperature for instantaneous and semi-instantaneous heat exchangers shall be 130 ֯F. Water in the potable hot water distribution system piping shall be no lower than 124 ֯F (prior to any temperature-reducing mixing valve or anti-scald device at the water outlet). Note, to limit the risk of scald injury, hot water in the distribution system piping should be maintained at the lowest temperature that will ensure the minimum of 124 ֯F throughout.

7) Cold water temperature throughout the potable cold water distribution system shall be maintained at or below 67 ֯F.

8) The water temperature in the hot and cold potable water distribution systems shall be monitored continuously to determine if temperatures are within the established control limits.

Temperature monitoring shall be conducted, at a minimum, in the following types of areas:

incoming water supply to the building, water storage tanks, hot water discharge at the hot water source equipment, hot water return proximal to the hot water source equipment, water at the return of circulation loops, and water supplied to representative outlets (e.g., loop or branch, hydraulic remoteness, flow).

9) Install mixing valves (can be supplemented with anti-scald devices) at all outlets where end users access water (e.g., sink taps, showers) from the potable hot water distribution system in order to prevent scald injury. The water temperature delivered from the outlet shall not exceed

110 ֯F. Mixing valves shall be positioned as close to the outlets as possible. Water temperature for emergency showers and eyewashes shall be between 60 ֯F and 100 ֯F. Determine the type(s) of mixing valve and/or anti-scald guard that will be installed in accordance with VA

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Plumbing Design Manual/Master Construction Specifications and the International Plumbing Code.

10) Thermal eradication (i.e., the raising of the hot water temperature to 160 ֯F - 170 ֯F and the flushing of outlets) is an option for emergency remediation of Legionella in hot water distribution systems. Select anti-scald devices and mixing valves that are amenable to this option.

11) Provide a cost-benefit narrative for installing point-of-use filters at specific outlets to prevent Legionella exposure to patients. Note, this method may be of particular use in areas that treat high-risk patients.

Identify Unused Branch Lines and Dead Legs

From the study and survey performed in April, 2016, a dead leg survey was performed and drawings of all the existing piping within the building were documented and have been included in the deliverables of this report. Building 1 was found to have 107 total dead legs and building 12 was found to have 4 dead legs of the following types; Pipe lengths greater than 10’ terminating at a cap, Pipe lengths greater than 10’ terminating at a closed valve, Pipe lengths greater than 10’ terminating at a fitting, Pipe lengths greater than 10’ terminating at an infrequently used plumbing fixture, and Pipe lengths greater than 25’ terminating at a frequently used plumbing fixture. Reference the deliverables of this study for a breakdown of all dead leg numbers, types, and locations. (4)

Dead Leg Elimination and Prevention Plan

The dead leg elimination and prevention plan is as follows; remove any pipe lengths greater than 10’ terminating at a cap, closed valve, or a fitting back to the branch line or main, and for any pipe lengths that terminate at a fixture that is infrequently used or 25’ or greater terminating at a frequently used system, improved recirculation is required, through proper calibration or upsizing of existing recirculation pumps.

Water System Management Points to Prevent Legionella and Protect from Scald Injury

Throughout building 1 and building 12, thermostatic mixing valves have been or will be installed to prevent scald injury to patients and employees while allowing the supply hot water temperature to be higher. A complete list of fixtures with mixing valves and those that need to be added has been included in this report’s deliverables. Some fixtures were found to be improperly adjusted and were either too hot or too cold, these fixtures have been noted and must be adjusted to prevent scald injury.

Continuous Monitoring of Incoming water

From the previous project 668-14-107 involving Legionella mitigation through chemical agents, two Phigenics smart water management systems were installed in the basement of building 1 and one system in building 12. All are capable of monitoring all of the required characteristics laid out in the scope of work, with some added sensors installed on the domestic mains for added temperature monitoring.

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FIG. 2: (Left) Phigenics Potable Water Analytics Unit Diagram, (Right) Example Installed Phigenics Unit Building 1 Room C001

Hot Water Storage at 140 ֯F Minimum

The information laid out in Figure 1 above supports the verdict provided in the scope of work where the domestic hot water should be maintained at a minimum of 140 ֯F and the cold water at a maximum of

67 ֯F. Current hot water temperatures have been found to be 140 ֯F, and will be maintained per the requirements of the “scope of work.” The vertical instantaneous steam booster hot water heaters currently in building 1 are designed to maintain the water at 140 ֯F, set points were placed at 143 ֯F for

WH 1-1 and 144 ֯F for WH 1-2 while on the site visit. These temperatures were confirmed from manual temperature readings on the pipe outlets from each of these boosters.

Cold Water Temperature Control – Add Cold Water Chiller

One method of mitigating Legionnaires in the domestic water of this hospital is to decrease the cold-water temperature through mechanical means. To accomplish this, a process chiller should be added on the exterior of each building and a chilled buffer tank near the supply of domestic water. The following is the sizing calculation of each of these components.

Calculating cold water chiller size:

1. Calculate the temperature differential (∆T):

Incoming water temperature ( ֯F) – Required Chilled Water Temperature ( ֯F)

2. Calculate BTU/hr:

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Supply gpm x 60 min x 8.33 x ∆T ( ֯F)

3. Calculate tons of cooling capacity (tons):

BTU/hr ÷ 12,000

4. Safety Factor:

Tons x 1.2

From the site survey, it was found that the incoming cold-water temperature was 57 ֯F. The goal is to keep the required chilled water temperature at 45 ֯F at the supply from the mechanical rooms. From the existing monitoring systems at the hospital, the average water usage and average peak can be used for the calculation, see Table 1 and Figure 3 below. It is assumed that 60% of the water from the supply is for cold water. Using this information, the chiller sizes can be determined below.

- Building 1 Chiller Size: 5.83 tons, a 7.5-ton unit will be used

- Building 12 Chiller Size: 2.19 tons, a 3-ton unit will be used

For the associated chilled water tank, manufacturers recommend the system volume to be 3 to 6 gallons per ton of nominal cooling of typical air conditioning applications and when temperature accuracy is critical, the recommendation is 6 to 10 gallons per ton of nominal cooling. The chillers that have been used for the basis of design are installed with tanks, the 3-ton unit has a 36-gal tank and the 7.5-ton unit has a 60-gal tank, which meets the requirement of the manufacturer’s recommend for critical temperature accuracy.

TABLE 1: Summary of Potable Water Usage Data October 2018 (2)

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FIG. 3: Potable Water Usage Data October 2018 (2)

FIG. 4: (Left) Koolant Koolers 7.5 Ton Chiller, (Right) Koolant Koolers 3.0 Ton Chiller

Water Temperature Control – Add Hot/Cold Water Recirculation

When taking temperatures at the sinks in many remote areas, there was a long delay in getting up to temperature, some employees claiming that on the 7th floor they never got hot water to the lavatories in the restrooms, this was evident by the long wait time to get to temperature, this is evidence that the water in the riser is not circulating properly. The causes of poor circulation are either the recirculation balancing valves are not calibrated properly, or the pumps are not powerful enough to manage the load of the whole building and needs to be addressed. The same conclusion can be inferred for the cold

9 | P a g e water, when taking the temperatures in some remote areas there was a long delay of stagnant water. In all of these areas, there is little to no movement if the fixtures are not regularly used, for that reason, a cold-water recirculation system is recommended to mitigate the stagnant water in the cold water and recalibration of the existing hot water recirculation so ambient temperatures are not reached in the domestic pipe.

Continuous Monitoring

Continuous monitoring of the system is critical for monitoring the health of the domestic water. Through the use of the existing Phigenics units, some added panels and sensors to meet the needs of this study.

All the information will be real-time and accessible to the VA staff. These new systems will be installed by CSN of Spokane. The locations, number of sensors and types of sensors added can be found in the deliverables of this project. Additional temperature sensors will be added near the extremities of loops to identify locations where recirculation is not flowing properly.

Install Mixing Valves at All Outlets Where End Users Access Water

Tables and drawings have been provided in the deliverables in this report to outline the existing conditions of the buildings, including whether a fixture is missing a mixing valve (highlighted in Tracking Sheets) or needs to be calibrated to prevent scalding. Multiple sinks throughout the buildings do not have mixing valves and will need them to be installed to satisfy the requirements of this study and to avoid the risk of injury (highlighted in Inventory Sheets). An example of a thermostatic mixing valve that could be installed is Acorn Controls Model ST7017, see cut sheet provided. The ER section of building 1 (rooms D105 through D135) currently has “dumb” mixing valves installed in the sinks that will need to be replaced with new lavatory tempering valves. These tempering valves are better able to control the outgoing hot water temperature to prevent scalding.

Thermal Eradication (Superheat-and-Flush)

Thermal eradication is an option to remove Legionella from the hot water piping where Legionella cannot survive above temperatures exceeding 140 ֯F. Increasing the temperature of the hot water from

140 ֯F to 160 ֯F could prove useful in killing off most of the Legionella present at more remote places within the hot water system; however, comes with some risks.

Firstly, at temperatures higher than 130 ֯F to 160 ֯F steel and copper pipe can start to corrode at an accelerated rate as explained in this excerpt:

“Water temperature can be an important factor in corrosion. Generally, the oxidation and diffusion rates of metals increase with temperature. Water that is unsaturated with calcium carbonate at temperatures encountered in domestic hot-water heating systems (54.4 to 71.1 ֯C [130 to 160 ֯F]) will usually be more corrosive. Accelerated failures will occur in copper and galvanized steel hot-water piping systems more often than in cold-water systems.” (3)

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This accelerated corrosion can cause pipe failure and pipe pitting, which, specifically with pitting, can cause a breeding ground for microbial matter and bacteria, continuing the cycle of bacterial growth this study seeks to resolve.

Secondly, if the Legionella is killed off, the dead biomaterial will remain if not properly circulated or filtered out, which can provide food for new bacteria to grow and sustain itself. Thermal eradication is a short-term response to a long-term problem. Thermal eradication while effective at killing off the biolayer immediately, it will return within a short time if the pipes are not maintained at a proper temperature.

“Thermal eradication is a temporary systemic disinfection modality. Recolonization of the water system will occur within weeks to months after a superheat-and-flush protocol if circulating temperatures are not returned to a baseline of 45 ֯C (113 ֯F) to 50 ֯C (122 ֯F).” (5)

Because of these reasons, it is recommended that proper circulation supplemented by filtration in key areas be the means to mitigate Legionella within the hot water piping and thermal eradication should be used sparingly in times of widespread Legionella.

Point-of-Use Filtration

Alternate, non-chemical related options were explored. Point-of-use filtration would be useful to further remove Legionella directly at the source. Systems exist that can be installed on the outlet side of the thermostatic mixing valves already in use and can remove 99.999% of bacteria and microbial matter in the water, but the filter would need to be replaced 2 to 3 times per year. It is recommended that these be used at high-risk patient rooms and not throughout the building, due to the increased maintenance and cost of these systems. These filters are to work supplementally with the thermal control of Legionella.

There are systems that can be effective at filtering out bacteria at the source (point-of-entry), and when working in tandem with point-of-use filtration can be a viable system that removes the bacterial matter from the water system. However, point-of-entry filtration is outside of the scope of this study, but is a method that could be considered in future Legionella mitigation studies.

Filtration Cost-Benefit Analysis

Point-of-use filtration is a key addition to help protect the most vulnerable patients at this hospital. This cost-benefit analysis uses the TripleClear point-of-use filter as a basis for the cost related to estimate the install and yearly maintenance cost. To start, below is a table of all rooms to be considered with these filters.

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Building 1: Building 12: Building 12:

A530 128 138 A530A 129 138A A530B 129A 139 A530C 131 140 B538 131A 140A B539 132 141 B540 133 142 B541 133A 142A B542 134 144 B543 134A 144A B544 135 145 B545 136 146 B546 136A 146A 9th Floor Janitor Sink 137

TABLE 2: Rooms Requiring Point-of-Use Filtration

From Table 2, there are 40 sinks that require filters. The cost of each of these filters needs to be broken down to install cost, and annual cost for filter replacement. The TripleClear filters are designed to last 4 months before needing replacement. Below is a table of the estimated install cost and annual cost to maintain these filtration options.

Unit Price $ 725.00 Annual Filter Replacement (x3 per year) $ 450.00 Install Labor $ 250.00 Labor cost to replace filters (x3 per year) $ 150.00 Install Cost per unit: $ 975.00 Total Annual Cost per filter: $ 600.00 Total Cost for install: $ 39,000.00 Total Annual Cost: $ 24,000.00

TABLE 3: Total Cost of Installation and Total Annual Cost of Point-of-Use Filtration

It is assumed that the labor for install includes material ordering and handling and an hour for install per unit. Unit price includes material for new pipe and fittings to sink from thermostatic mixing valve and mounting for the filter. With filters needing replacement 3 times per year and the amount for filter replacement and labor are total for each of these annual replacements.

Conclusion

A combination of cold-water chillers, the addition of cold-water recirculation, and point-of-use filtration in critical areas are recommended to combat the large stretches of stagnant water within the cold-water piping at this hospital. Hot-water recirculation exists; however, is lacking in some of the extremities of the building, causing water temperatures to reach or be near ambient. The existing hot water recirculation balancing valves should be adjusted to allow more flow to the extremities of both buildings 1 and 12. Thermal eradication can be used to reduce the Legionella count initially, but due to the risk of pipe damage and erosion, should be used sparingly. Mixing valves need to be installed properly to reduce the risk of scalding during these thermal eradication protocols.

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It is the responsibility of the owner to determine from the information provided in this study, what is most effective and feasible plan that best fits their budget and the safety of their patients and employees.

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References

1) J. Rogers, A. B. Dowsett, P. J. Dennis, J. V. Lee, and C. W. Keevil. 1994. Influence of Temperature and Plumbing Material Selection on Biofilm Formation and Growth of Legionella pnewmophila in a model Potable Water System Containing Complex Microbial Flora.

2) B. Carleton, A Esvelt. 2018. Secondary Water Disinfection Project Report Building 1 Public Water System and Building 12 Public Water System

3) American Water Works Association, AWWA. 1996. Internal Corrosion of Water Distribution Systems – Second Edition. Page 501.

4) L & S Engineering, 2016. Dead Leg Summary – VA Spokane Legionella Hot and Cold-Water Systems As-Builts Project 668-14-107.

5) Y. E. Lin, J. E. Stout, V. L. Yu, R. D. Vidic. 1998. Disinfection of Water Distribution Systems for Legionella.