1. LEGIONELLA UPDATE
Québec 2012:
Learned, Done & to Do
Alain Trahan,
P.Eng.
20th of March
2014

2. Cooling towers are the outside
heat sinks that exhaust the heat
carried by the air conditioning
cooling water circuit used in
buildings HVAC systems.
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What is a cooling tower?
Pump
HVAC
Air
conditioning

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What is a cooling tower?

4. Step 1:
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How it works
Step 2:
Magic of evaporation
Liquid water + energy Water vapor (with less energy remaining in the liquid)
Evaporative cooling

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How it works (in a bio-clean world !)
Dry air
Humid air (evaporated water)
+
Water loss (drift)
Dry air
Warm water
from AC
Cool water
to AC
Demister
Water distributor
Fill
Fan
Water make-up
Typically between
85 and 95 °F.

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In the real “dirty” world…
Dry air Dry air
Wind
Building “fresh
air” intake louvers
Building “fresh
air” intake louvers

7. Simple definition:
An ubiquitous aquatic organism that causes Pontiac Fever
and Legionnaires’ disease (lung infection) if inhaled.
Thrives in temperatures between 77 and 122 °F.
Travels from infected water source through aerosolized water
droplets.
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Legionella pneumophila
In the United States…
• 10,000 to 20,000 people get infected by legionella every year.
• Various studies have shown that some 40 to 60% of tested cooling towers contained Legionella.
• Legionnaires’ disease mortality rate: 10 to 15% of those infected.
Cooling tower drift

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Biofilms
• Form on surfaces in aquatic systems.
• Often resistant to biocides.
• Monitoring is difficult.
• Release organisms into bulk fluid.
• Cost the US nation billions of dollars yearly in equipment damage, product
contamination, energy losses and medical infections.
Bacteria

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The old way
Make-up
Warm water
Cool waterBlow-down
CHEMICAL$$$
(transport, storage, handling)

10. Québec 2012: Source?

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Québec 2012: 11 km!

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24% had Lp sp1!

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Before: ASHRAE 62.1-2010
• Specifies minimum distances between CTs vs
Air Intakes & Kitchen exhausts.
• Not frequently applied especially by architect.
• Mitigation :
• UVGI of fresh Air: always when high risk
occupants
• Project the CT plume higher
• Prevent food particles from reaching the CT.

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Before: Pesticide Regulatory System
• Pesticides need to be approved by HC for each
use with application guidelines.
• Sellers & applicators need certification.
• Reality :
• Provincial application.
• No processes for CT biocides!
• >75% non compliance in commercial blds for
concentration, contact time or hydraulics.

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Before: Guidelines not Standards
• ASHRAE 12-2000
• AWT 2003 (2008)
• CTI WTB-148 (2008)
• CDC
• Reality :
• Contradict each other.
• Incomplete.
• Control is left to water treatment as a last step
in general.
• Voluntary: doesn’t work.

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Before: Guide for Hospitals in 2005
Very Generic

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During
• ‘Hopes’ of official that situation would go away
by itself…
• High dose oxidizing biocide only.
• CDC protocol ASSumes surfaces are clean &
circulation in whole system.
• Plan created during crisis.
• Localisation & owners unknown.
• No early public communication.

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Lessons : Emergency planning
• Have a plan of action:
• If this then that, etc.
• What, Where, How, When, Who.
• Work upstream of Legionella.
• Do not ASSume or ‘Hope-away’.
• Legislate.

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Lessons : Immediate steps
• Stop the fans!
• Ultra High Efficiency drift eliminators
• Decontamination:
• Clean first to remove deposits.
• Circulate in whole system.
• Fast acting biocide that keeps its efficiency
throughout the system.
• Know system volume.
• Analyze biocide concentration

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Lessons : Involve outside experts
Interview with an official from the health agency
DSP followed by one with the building code
agency, RBQ

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Lessons : Involve outside experts
Interview with an official the RBQ – Building Code
Agency

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After: Québec Law 2013, phase I of III
• The Excellent:
• Mandatory documentation of actions
& tests results.
• Schematics of system.
• Mandatory maintenance plan signed
by at least one professional.
• 40 inspectors actually going to each
site.

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2013 Law: Form signed by Owner!

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4 Dimensions of Risk Management

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Interrelation of the 4 dimensions
Law Description
Water
Treatment
Hydraulic Solids Drift
402.1 Overwintering X X X X
402.2 Operational stops X X
402.3 Decontamination X X X X
402.4
Corrosion, Scale,
Organics
X X X
402.5 Schematics X X X
402.6 Water treatment quality X X X
402.7 Chemicals X
402.8 Mechanical Verification X X

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Law 2013, Phase I : the Good
• Any law is great.
• Well made technical guide & training
sessions
• Inspectors systematically validate
backflows & existence of signed
documentation
• Tickets with 7 days to comply.
• Inspectors take pictures.
• Indicators & Lp analysis with action
levels

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Law 2013, phase I: the Good
Level
Result
(logs/L)
Action
Normal < 4
Intervene 4 - 6
Identify causes. Validate efficiency of new
measures.
Sanitary Risk > 6
Apply Decontamination. Identify root
causes & correct maintenance plan.
Validate efficiency of new measures.
Test for Legionella pneumophila.
Legionella pneumophila Test concentration & Action Levels

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2013 Phase I: Lessons
• Plans : ‘copy-paste’
• Schematics have or are:
• Not up-to-date
• No flow speed or materials of
construction
• No zones of stand-by operation
• Inspectors have no powers.

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After: Coroner’s report, 2013-09

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After: Public Health Report

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After: Media reports
• Radio-Canada (CBC) had a 30
minutes piece that showed
delayed actions by officials.

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After: Worker’s Health & Safety

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Graduated Risk Management

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After: Sampling Guide

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After: Very Good CT Guide

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After: Excellent Full Day Training
Michelle Merchat, Climespace

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Law 2014, phase II: the Excellent
• Specific cleaning step
independant from
decontamination
• Stop the fans if log 6 or more
• Identification of sampling points

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Law 2014, phase II: the Good
• Mandatory testing for Legionella
p. every 30 days at most.

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Interrelation of the 4 dimensions
Law Description
Water
Treatment
Hydraulic Solids Drift
402.7a Sampling Points X
402.8 Chemicals X
402.9 Mechanical Verification X X
406 Log book X X X
407+
408
Sampling procedures X X
417 4-6 logs Action Plan X X X X
418 Interfering flora X x
419 >6 logs, Action Plan X X X X

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Interrelation of the 4 dimensions
Law Description
Water
Treatment
Hydraulic Solids Drift
402.1 Overwintering X X X X
402.2 Operational stops X X
402.3 Decontamination X X X X
402.4+
402.9
Preventive Cleaning X X X X
402.5
Corrosion, Scale,
Organics
X X X
402.6 Schematics X X X
402.7 Water treatment quality X X X

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Beyond: What we do
•Guidelines, Standards & Regulations
are a minimum
•ASHRAE 188 methodology
•Zero risk does not exist.
•Risk = Probability x Consequences
•Multiple barriers: if one fails we avoid
an outbreak
•Non-oxydising biocide measurement
•On-site one hour Legionella
measurement!

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Risk Assessment: beyond 62.1
• Risk = concentration x duration.
• Occupants: long exposition.
• High riks by Common Sense :
– Close to ground, next to parking, bld entrance.
– Next to roof terrasse, balconies.
– Adjacent to open windows.
• Mitigation: UHE eliminator, lower °C, continuous
or low tox or permanent biocide. Ex: Cu/Ag
ionisation

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Beyond: Flow Speed
•Higher flow speed = less biofilm
•5+ fps up to 10 fps especially for
horizontal lines.
•No dead legs: mitigation approach

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Vulnerability of CT
Contamination Mitigation
Insects from
waterway
Intake screens
Pollen, leaves,
etc
screens, basin sweep,
filters, continuous
biocide, etc.
Algea
Sunlight shade, Cu
ionization
Dust filter, basin sweep
Vulnerability vs environment thru seasons?

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Beyond: Deposits & Corrosion
• Variable speed motors to avoid:
–Total evaporation deposits
–Stray current corrosion.
• Mechanical action to remove deposits.
• Zinc coatings are subject to white rust
corrosion.
• Copper to steel surface ratio.
• Is it clean?

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Back-Flow Preventer
• Biocide means ‘kill the biological’
• Some are banned from hospitals!

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Water Meter & Level Control
• Towers purge water but take no make-
up?!?
• No moving parts Water meter.
• Convert from continuous water MU to
ON-OFF.

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Green & Bio Chemicals
• Feels good to use these, doesn’t it?
• Banning zinc? used in baby cream with
20%+ ZnO.
• No area in Canada has too much Zinc.
Zinc is essential to life. No Zn in the
environment means no Zn in our food.
• Life-cycle approach rather than Bio

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Local Control: Very bad

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Local Control: Average
•Most common currently
•°T compensated conductivity by dual
carbon probes
•Flow switch, Pre-bleed, Bleed block,
Water meter input, permanent program.

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Probe
• Toroidal Conductivity :
deposits & chem.
Valve
• Ball valve, not solenoid :
plugging.
Meter
• No moving parts & low
flow range.
Level
• Chem inventory, water MU
control.
Wireless • Meter, valve, level, etc.
pH+ORP • Oxydizing biocides dosing.
Record
• Conductivity, °T,
Meter, etc.

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Local Control: Best
• Internet accessible PLC.
• Continuous inhibitor measurement
• Change µS depending on operating mode
• Increase cooling capacity without
changing the system.

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Beyond: Internal Tank
•Last in, last out: hydraulic factor closer to
1
•PE instead of steel
•Easy to access
•Bottom does not favor accumulation
•Affects biocide selection & risk strategy

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District Cooling
•No, ZERO Legionella risk
•No island effect, less smog
•Energy & GHG savings
•No potable or net water use

55. Thank you!
Alain Trahan, ing.
atrahan@h2obiotech.com
(514) 943-9044
Prepared with
Philippe-Andre.Boileau@chimisteconseil.com

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Copper - Silver Ionization
Input: 110-240VAC 50/60Hz
Output to electrodes: 0 to 42V