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Engineering Keys for Legionella Control
Jeff Boldt, PE, LEED® AP, HBDP
Principal – KJWW Engineering
• Member ASHRAE SSPC-90.1–Chair 90.1 Hydronic & Elevator WGs
• Member ASHRAE SSPC-90.1
• Consultant to 62.1
• Something to Standard 55
• Member GPC-36
• PE - M and FP
• “Jeff Boldt Nerd”
Learning Objectives
• Understand the challenges of Legionnaires’ disease prevention and control of Legionella in water systems
• Know current trends in epidemiology (disease transmission), diagnosis and treatment of Legionaries’ disease
• Distinguish and be familiar with Legionella disinfection and control methods, including chemical and non-chemical methods
• Apply the information from this seminar to write specifications for water treatment in cooling water systems
ASHRAE is a Registered Provider with The American Institute of Architects Continuing Education Systems. Credit earned on completion of this program will be reported to ASHRAE Records for
AIA members. Certificates of Completion for non-AIA members are available on request.
This program is registered with the AIA/ASHRAE for continuing professional education. As such, it does not include content that may be deemed or construed to be an approval or endorsement
by the AIA of any material of construction or any method or manner of handling, using, distributing, or dealing in any material or product. Questions related to specific materials,
methods, and services will be addressed at the conclusion of this presentation.
• What’s Legionellosis
• Existing Standards– ASHRAE Guideline 12
– CTI Guideline 208
– ASHRAE Standard 188
• What About My Designs?
• What’s My Risk?– Minimal plumbing discussion – this is ASHRAE
OUTLINE
What’s Legionella?It’s Pneumonia
• Most cases not diagnosed as LD
• Legionellosis cases >3X in 10 years
• Outbreaks create publicity and outcry
• ~4% of pneumonia cases
• 8-18,000 cases per year in USA (CDC)
• Usually develops 2-14 days after exposure
• >10% of cases are fatal (CDC)
LEGIONELLOSIS = PHNEMONIA
• Elderly
• Smokers
• Immunocompromised
• ~25% of cases have no risk factors
WHO IS SUSCEPTIBLE?
• Legionella is a bacteria
• Legionella Pnemophilia, serogroup 1
– Some antibiotics are effective
– Levofloxacin
– Not Penicillin
WHAT IF I HAVE LD?
• Must be inhaled
• Potable water (#1 risk)– Is CW a significant risk?
• Pittsburgh VA deaths
• Warm water (cooling towers)– Less total risk, but often more publicity
– 13 deaths in Quebec (180 cases)
– NYC deaths
SOURCES
ASHRAE Guideline 12
• Available free from some tower manufacturers’ sites
• Minimizing the Risk of Legionellosis Associated With Building Water Systems
• Standard of Care
• Most cases are not outbreaks
ASHRAE GUIDELINE 12
• Legionellae are bacteria – not viruses• Antibiotics are effective• Risk is higher for elderly, smokers, immune
suppressed• Amplification factors• Water 77F-108F, stagnation, scale, sediment,
biofilms• Must be inhaled
ASHRAE GUIDELINE 12
• Copper inhibits growth somewhat
• Controlling other microorganisms may be the best strategy
• HVAC Sources:
– Cooling Towers
– Humidifiers
GUIDELINE 12
• Hard to keep temps outside of 77-108F
• Many or most have detectable Legionellae levels
• Maintain, clean, treat water with biocides
• Employ (specify) qualified water treatment specialist
• Clean cold water basin when dirt, organic, or debris is visible or sampled
COOLING TOWERS (ETC.)
• Require MSDS for chemicals (specify)
• Specify water treatment to minimize scaling (phosphonates, phosphates, polymers, etc.)
• Minimize corrosion (phosphate, azoles, molybdenum, zinc, etc.)
• Alternate biocides
COOLING TOWERS (ETC.)
• If system is shut down over 3 days, drain entire system– Consider corrosion (my note)
– Possibly bypass and circulate biocide periodically
• Prior to starting fan, treat system with biocide (4-5 ppm free chlorine for >6 hours suggested at 7.0-7.6 pH) and circulate prior to starting tower fans
TOWER START-UP / SHUT-DOWN
• Turn off pumps before fans to dry media
SHUTDOWN
• Remove debris from tower and sump(s)
• Circulate and verify biocide concentrations without starting fans for >6 hours
TOWER START-UP OF UN-DRAINED SYSTEMS
• Locate as far as possible from air intakes & operable windows
– 62.1 has minimums also
• Avoid organic sources (kitchen exhaust, truck bays)
• Consider prevailing winds and public entrances
SITING
• Steam humidifiers are not a concern, unless water stagnates during off times
• Wetted media humidifiers tend to be below 77°F because they are used in low wet-bulb areas
HUMIDIFIERS
• Consider ozone generators
– Controversial
• Clean and Flush entire cooling loop monthly
– I’ve never heard of any owner doing this
• No confirmed cases related to air washers, evaporative coolers/humidifiers, or steam humidifiers
CHEMICAL TREATMENT – EVAP. COOLERS, ETC.
• May be useful – or not
• Be careful with sampling, culturing, sample handling, shipping, lab methods, etc. so results are consistent.
MONITORING
CTI Guideline 208
Best Practices for Control of Legionella
• 68-113°F favors growth (vs. 77-108°F)
• 99°F is optimum
• Does not survive above 140°F
– For how long???
CTI - ECOLOGY
• Halogen oxidizers are recommended
• Ozone, peroxides, UV, ultrasonic, and non-oxidizing biocides work in limited circumstances
• Most recommendations are for periodic cleaning and testing – not design
• Most agencies’ guidelines do not recommend routine testing
CTI RECOMMENDATIONS
• Feed chlorine or bromine and maintain 0.5-1.0 ppm as Cl2
• Effectiveness is reduced at higher pH– Chlorine is effective to 8.0– Bromine is effective to 8.5-9.0
• Discharge halogens legally – often to sanitary sewer
• Biodispersant/biodetergent may aid in penetration and increase efficacy
• Periodically use non-oxidizing biocides
CTI – ROUTINE TREATMENT
• Eliminate Stagnant areas
• State-of-the-art, high-efficiency, nested drift eliminators, are suggested
• System design engineers should provide discharge piping and equalizers to move water with no dead flow locations. Special attention should be paid to equalizer piping to ensure these areas are not stagnant.
CTI – DESIGN ISSUES
ASHRAE Standard 188
• The Purpose of this standard is to establish minimum Legionellosis risk management requirements for building water systems
PURPOSE
• Potable water systems
• Non-potable water systems
• Whirlpools and spas
• Ornamental fountains
• Humidifiers
SCOPE
• NY City adopted sections 5, 6, and 7.2
• Written in mandatory language
• Will be the standard of care
• 5 Public Reviews
• Sections 4.1 and 8 include “Designer Requirements”
– IMO some are Owners’ responsibilities
NOT A CODE, BUT…
• A Program utilizing the risk management principles in the following subsection shall be used to reduce the risk of legionellosis…
• Identify the persons on the Program Team responsible for developing and implementing the Program and the tasks for which they are responsible. – When???
PROGRAM & PROGRAM TEAM
POSSIBLE ISSUES
• Implies prohibition of fill valves below the basin overflow level
• Daily shock disinfection of whirlpool/spas
• Program documents shall include cleaning procedures when commissioning misters, atomizers, air washers, humidifiers
• Drawing of distribution system including monitoring points for temperature, sampling points, and treatment points
• Detailed instructions for commissioning of all building water systems shall be provided by the designer… Including…
INSTALLATION DRAWINGS
• Must be within 3 weeks of beneficial occupancy
DISINFECTION
• Primary responsibility
• Plans for regular activities
• Emergency plans
• Program Team decides about water testing– If
– How much
– Criteria
OWNERS
• Flush outlets before sampling?– Study – Janet Stout et al
• Recommends not flushing– Represents what user does
– Flushing reduces counts
• Sample size– 100-200 ml is enough
– Bottles from lab have neutralizer to remove Cl
– Less shipping/handling than 1L
– Ship in insulated containers
TESTING
• Does shipping time affect results?
– 2014 study by Dana Flanders et al
• Tested samples immediately and after 24 hours
• Minimal difference in results
– Study by Janet Stout et al
• Multiple sites
• 0, 1, 24, 48 hours
• No change at 24 hours – 2% at 48 hours
SAMPLE SHIPPING
• Quick Methods
– DFA – Direct Fluorescent Antibody Staining –sometimes false positives
– ICT – Immuno-chromatographic test
• Got negative test at >3,000 CFU/ml
– PCR – Polymerase Chain Reaction – tells species type, but not counts – hospitals have
• CDC doesn’t recommend for routine testing
– Dip slide – Total count only
PICKING A TEST METHOD
• CDC
– “Use of PCR for identification of Legionella is not recommended until more data regarding sensitivity and specificity of procedures are available”
• Progressing – Nested Enzymes
MOLECULAR METHODS - PCR
DIP SLIDE
• Culture Methods - Proficiency Standards– ISO 11731 (parts 1 &2)
– ASTM D 5952
– International – HSE L8 ACP 2013
• Labs use different methods– Pretreatment, filtration, culture media
– Presumptive agglutination or definitive sequencing?
• CDC Elite labs is a minimum – Not all equal– Variations in duplicate samples
PICKING A LAB
• No requirement
• Maybe if going into CT known to have LD
• Maybe power washing CT
PPE FOR PEOPLE TESTING?
• From the basin is most representative
WHERE TO TAKE CT SAMPLES
• Zero is good, but generally not considered necessary
• 58 named species
• Half implicated in human disease
• Worry about pneumophila, serogroup 1
• 65% of studied hospitals tested
• >1,000 CFU is probably trouble
• Program Team decides
HOW MUCH LEGIONELLA IS ACCEPTABLE?
• Alternating Dual biocide– Oxidizing + Non-oxidizing
– Bromine +Quaternary Amine
– Probably Chlorine + Quat (not in test)
– ASHRAE RP-1361• All non-chemical methods were ineffective
– Magnetic
– Electric pulsed, Electric static
– Ultrasonic
– Cavitation
CHEMICAL TREATMENT
• Establish baseline during maint period
• Test for Legionella Pneumophila, Serogroup 1
• Periodic testing
– Best = send cultures to CDC Elite lab
– Dipslide or pen gives total count – non-specific to Legionella
TEST WATER
• Minimize time inside towers
– Direct drive to eliminate belt/gear maintenance
– Fans/Motors with external maintenance
MAINTENANCE STAFF
• Distance as much as possible
• Minimize droplets
– High performance drift eliminators
• Hybrid Towers??
– Just my theory
PASSERS BY
• My Suggestion to the Tower Industry
– Think of how you handle fume exhaust
DISCHARGE THROW
• Maximize distance to OA intakes
– Consider prevailing wind (odds)
BUILDING OCCUPANTS
• Circulate water and treat with biocides >6 hours before fans start
• Nested “high efficiency” drift eliminators
• Run fans slowly after water flow stops
• Include sidestream filters
SPEC ITEMS – COOLING TOWERS
Open Systems . . . . . .expose system
components to
airborne
contaminants
Fouled Plate Exchanger
Fouled Tube Exchanger
• 77°F minimum CW temperature?
– Guideline 12 mentions this, but not 188
– VA has requirements
DOMESTIC WATER
ASHRAE Standard 188
What’s My Risk?Higher? �Lower? ☺
• No A/E LD losses prior to 2015
• What should we expect in the future?
WHAT’S XL CATLIN SAY?
• If you address 188 – Risk goes down ☺
• If you don’t – Risk goes up – A LOT �
JEFF’S OPINION
• Sidestream filters
• Avoid dead legs
– Level equalizing
DRAWING ITEMS – COOLING TOWERS
• Drawings & Specs
– Plumbing
– HVAC
– Commissioning
• Contracts
TEAM TO ADDRESS
WHAT WE DID
YOU CAN INFLUENCE ASHRAE STANDARDS!
• Have a suggestion?
– Email me or any ASHRAE committee member
• Lowest Overhead method
– Submit a CMP
• More OH, but formal response is required
– Call and discuss
• ASHRAE involvement has benefits!!!
– Connections – Knowledge
