DWQ-2025-004072

Centra I Va lley Water
Recla mation
Facility
eecElYqo
Board Members
Debra Armstrong, Chair
Don Russell, Vice Chair
Kim Galbraith
Brett Hales
Cheryle Hatch
LeAnne Huff
Keith LordMAY O83OF
General Manager
Phillip Heck, Ph.D., P.E.
May 5, 2025
Utah Division of Water Quality
Mr. Dan Griffin
PO Box 144870
salt Lake city, uT 84114 - 4870
Subject: Notice of UV Disinfection Process Upset - April 30,2025
Dear Mr. Griffin:
This letter is being submitted to you in accordance with Part VI. H. of our permit,
to report an Upset Condition of the IfV system that occulred at the Central Valley
Water Reclamation Facility (CVWRF) on April 30,2025. The sequence of events
that caused the upset and actions CVWRF took to remedy the process upset are
described in the following paragraphs:
The #3 Jenbacher engine generator shut down due to overheating. This was caused
by a fault at the variable frequency drive (VFD) on the engine's heat recovery
pump. Shortly thereafter,the #4 Jenbacher engine shut down due to an air
fuel/ratio issue related to losing the #3 Jenbacher engine. The loss of both
Jenbacher engines resulted in apartial loadshed of plant equipment, inciuding the
A buss in the secondary area. Satellite engine #9 started as designed. Engine #9
ran for 5 minutes and then shut down. UV Channel #1 is powered by the A Buss.
[fV Channel #1 lights shut down. Channel #4 was also online at the time (powered
by the B Buss) and it remained on-line.
The equipment failures have been investigated. The cause of the #9 satellite
generator shutdown was a linkage failure at its fuel pump. This has since been
repaired and the #9 satellite generator has been tested. The VFD for the heat
recovery pump for the #3 Jenbacher engine has been evaluated and nothing has
been found. Our cogen supervisor ran the heat recovery pump through the
weekend and it ran flawlessly. Our cogen team and our electrical team will
continue to monitor this VFD. Additionally, it is unknown as to why only the A
Buss tripped during this loadshed event. Until this is determined, we have
800 west central valley Road, salt Lake city, uT 84119-3379 . (801) 9'73-9100 . [phone]
Notice of UV Disinfection Process Upset - April 30, 2025
Page 2
increased our loadshed setpoint to 4500 kW, eliminating loadshed events caused
by Jenbacher engine failures based on cuffent plant power demand. CVWRF is in
the process of developing a new loadshed system.
Power for Channel #1 was off from 22:55 unti1,23:03. UV channel #1 was fully
on-line at23:06. It has been calculated that279,657 gallons discharged through
IfV channel #1 without the lights on. Samples were collected from the plant and
Millcreek per the UV system failure standard operating procedure (SOP). E. coli
samples were collected from the UV influent, plant effluent, Millcreek upstream of
plant effluent, and Millcreek downstream of plant effluent. Sampling results are
provided below and indicate that there was a temporary increase in E. coli levels in
the plant effluent due to the outage of channel #1:
Sample 1 -UV influent, E. coli ->2419 MPN/100 mL
Sample 2 -rJV effluent, E. coli ->2419 MPN/100 mL
Sample 3 - Millcreek upstream of plant effluent, E. coli - 365.4 MPN/100 mL
Sample 4 - Millcreek down stream of plant effluent, E. coli - 5I7.2 MPN/100 mL
The weekly geomean effluent E. coli level for this period was 100.3 MPN/100 mL
(including the sample taken during the event) which is in compliance with the
permit requirement (157 No./100 mL). Due to the short duration of the event, and
compliance with the weekly geomean limit, it is very unlikely there were any
negative effects on the receiving water.
Please let us know if you have any questions or comments regarding this event
Sincerely,
Y WATE,R RECLAMATION FACILITY
Burton, M.S., GCHRM
Plant Superintendent
Cc: Phillip Heck, Ph.D., P.E. General Manager
Brandon Heidelberger, P.E. Assistant General Manager