HomeMy WebLinkAbout07.b. Update on 01-16-19 Power Outage at Treatment Plant Page 1 of 6
Item 7.b.
,ek CENTRAL SAN
SANITARYCENTRAL CONTRA COSTA , .
March 7, 2019
TO: HONORABLE BOARD OF DIRECTORS
FROM: NEIL MEYER, PLANT MAINTENANCE DIVISION MANAGER
REVIEWED BY: ANN SASAKI, DEPUTY GENERAL MANAGER
ROGER S. BAILEY, GENERAL MANAGER
SUBJECT: RECEIVE UPDATE ON JANUARY 16, 2019 POWER OUTAGE AT THE
TREATMENT PLANT
On January 16, 2019, the treatment plant experienced a power outage. Plant Maintenance Division
Manager Neil Meyer and Utility Systems Engineer Mark Cavallero will present an update regarding the
incident.
Strategic Plan re-In
GOAL TWO: Strive to Meet Regulatory Requirements
Strategy 1 - Strive to achieve 100%permit compliance in air, water, land, and other regulations
ATTACHMENTS:
1. Presentation
March 7, 2019 Regular Board Meeting Agenda Packet- Page 81 of 107
Page 2 of 6
TREATMENT PLANT POWER OUTAGE
JANUARY 16, 2019
Ads' '
Board of Directors Meeting
March 7, 2019
Neil Meyer
X11 -
Plant Maintenance Division Manager
Mark Cavallero
Utility Systems Engineer
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Slide 1 - '
ELECTRICAL SYSTEM OVERVIEW
• Pacific Gas and Electric (PG&E) utility power feeds -
Central San's treatment plant main substation with �� +
115 W. From the secondary of the PG&E + .�
transformer, power at 12 kV is distributed via the
primary Substation 82 through dual redundant
feeders to the other 9 substations throughout the
treatment plant for each wastewater treatment
process area. ,,,,
�e
Slide 2 = j
: . . -
March 7, 2019 Regular Board Meeting Agenda Packet- Page 82 of 107
Page 3 of 6
ELECTRICAL SYSTEM OVERVIEW
•
Power at 12 kV goes �z �•"� _ _ - ,��-
into Substation 40 _'_-- _
(Filter Plant)via two - = -
redundant feeders from ;- — ,
Substation 82.
• Power at 12 kV also
goes into Substation 73 -- — ". - _-
to the Solids �- �.=- - R --
Conditioning Building. Arl -_ — �= —
��i!: T•ETa1EHT PuwT � _ _
Slide 3 '
EVENT DESCRIPTION
• On January 16, 2019, a storm delivered
approximately 1.5 inches of rain and
i
148 MGD to the treatment plant.
• A 12 kV electrical ground fault resulting
in a blown fuse at Substation 40 led to
a sudden fluctuation of power within the
treatment plant.
• The ground fault occurred in the
transition box connecting the 40AT1
Transformer and the air disconnect
switch at Substation 40. SubsaFauitat
Substation
• A protective relay tripped at 23:04 that
opened Breaker 82AB1 resulting in loss Blown use --
of imported PG&E power. Location
Slide 4
March 7, 2019 Regular Board Meeting Agenda Packet- Page 83 of 107
Page 4 of 6
EVENT DESCRIPTION
• The PG&E and Cogeneration load was at 4.0 MW prior to the event.
• To compensate for the loss of PG&E power, Cogeneration spiked from 2.8 MW to 3.5 MW,
which caused engine combustion temperature to exceed its limit.
• Cogeneration shutdown to protect itself from any damage and opened Substation 73,
Breaker 73DAB2.
• Standby generators started but did not synchronize and close into treatment plant out of
phase, which tripped circuit Breakers EM 501 and EM 503.
• Treatment plant was without power.
• At 23:21, approximately 16 minutes later, Breaker 82AB1 was reclosed by staff, and PG&E
import power was restored.
Slide 5 '
EVENT DESCRIPTION
• The treatment plant is equipped with a Load Shed System to remove non-essential
electrical loads and keep critical equipment online in the event of a PG&E power
failure.
• The Load Shed System did not function as intended.
• Inability to shed electrical load led to shutdown of Cogeneration and failure of
standby power.
• This led to the treatment plant power outage and the opening of the emergency
bypass damper.
Slide 6 '
March 7, 2019 Regular Board Meeting Agenda Packet- Page 84 of 107
Page 5 of 6
OPERATIONAL IMPACT
• No NPDES Permit violation.
Emergency
• Final effluent was bypassed to the wet B4Pass5tack Steam-Powered
Yp Secondary Treatment
weather basins. Blowers
Furnace
• One Reportable Compliance Activity for Exhaust Stack
furnace bypass damper operation.
• Under normal conditions, multiple-hearth mu le pHunh ry
furnace exhaust travels through the dry wrrraoe Scrubber Waste Heat wet InducedRecoveryBoiler Scrubber Draft Fan
scrubber all the way to the furnace exhaust
stack. Ash Reuse(Fertilizer Amendment)
• The emergency bypass damper opened to
protect worker safety and protect downstreamllevratered
equipment from possible thermal damage. Solids —5oifds— Ah—riue Gzr(Steam
Slide 7 '
ACTIONS AND IMPROVEMENTS
Near Term
• Electrical Shop replaced all three fuses at Substation 40 and repaired damaged buss bar
section and condensation heater.
• Hired P. R. Engineering, Inc., to review the event data, relay settings, and assist with
implementing any Protection Engineer changes.
• Investigate potential adjustments for the time delay on Breaker 82AB1 Under and
Overvoltage Relay.
• Investigate potential adjustments for the time delay and pickup on standby generator.
• Other adjustments as recommended.
• Test and verify the Load Shed System functionality.
Slide 8
,Or 5140 to
March 7, 2019 Regular Board Meeting Agenda Packet- Page 85 of 107
Page 6 of 6
ACTIONS AND IMPROVEMENTS
Low Term
• Investigate additional replacement of electrical equipment as part of Capital Projects.
• The rehabilitation efforts of the Filter Plant's Substation 40 are expected to improve
equipment reliability.
• The Wet Scrubber Replacement Project is part of an Solids Handling Facilities
Improvement Project approved in April 2018. The new wet scrubber will be designed
to treat the high-temperature furnace exhaust gas during a bypass event, minimizing
the release of unabated emissions through the bypass damper.
Slide 9 '
QUF"*TIONS*.2
COMMENTSIi
,...
R, Slide 10ft
March 7, 2019 Regular Board Meeting Agenda Packet- Page 86 of 107