HomeMy WebLinkAbout04.a. Receive update on Primary Level Control Valve 22227 Page 1 of 5
Item 4.a.
CENTRAL SAN
October 29, 2019
TO: ENGINEERING AND OPERATIONS COMMITTEE
FROM: EDGAR J. LOPEZ, CAPITAL PROJECTS DIVISION MANAGER
REVIEWED BY: JEAN-MARC PETIT, DIRECTOR OF ENGINEERING AND TECHNICAL
SERVICES
ROGER S. BAILEY, GENERAL MANAGER
SUBJECT: RECEIVE UPDATE ON PRIMARY LEVEL CONTROL VALVE 22227
Attached is a presentation on the history and current status relating to the Primary Level Control Valve
22227.
Strategic Plan Tie-In
GOAL TWO: Strive to Meet Regulatory Requirements
Strategy 1 - Strive to achieve 100%permit compliance in air, water, land, and other regulations, Strategy 2- Strive to
minimize the number of sanitary sewer overflows
GOAL THREE: Be a Fiscally Sound and Effective Water Sector Utility
Strategy 2- Manage costs
GOAL FIVE: Maintain a Reliable Infrastructure
Strategy 1 - Manage assets optimally throughout their lifecycle, Strategy 3- Protect District personnel and assets from
threats and emergencies
ATTACHMENTS:
1. Presentation
October 29, 2019 Special EOPS Committee Meeting Agenda Packet- Page 59 of 90
Page 2 of 5
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REPORT ON PRIMARY LEVEL
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aA CONTROL VALVE (CV) 22227
Engineering and Operations Committee
October 29, 2019
- -_ Edgar J. Lopez, P.E.
Capital Projects Division Manager
WHY IS THE CV 22227 SO CRITICAL?
PRIMARY EFFLUENT CONTROL STRUCTURE
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October 29, 2019 Special EOPS Committee Meeting Agenda Packet- Page 60 of 90
Page 3 of 5
WHY IS THE CV 22227 SO CRITICAL?
CV 22227 is a 72-inch butterfly open channel valve used
for:
Controlling the level in the primary sedimentation
tanks to allow for scum removal.
Up to 110 million gallons per day of flow can go
through this valve to the Primary pumps.
A single channel feeding the Primary and standby
effluent pumps, for which there is no redundancy;
however, other valves can be used to bypass flow
to the holding basins.
VALVE FAILURE IN 2011
W rLft Annomcem Ls
3un0 2,201 l
Page 5 of 5
t} Primary Effluent Control Valve Actuator Failure
On Saturday,May 21,2011,the Primary Effluent Control Valve,CV22227,failed
in a half open position. This vahre is used to control the level in the Primary
Sedimentation Tanks,therefore adjusting as flow changes throughout the day. A
mechanical maintenance crew was called in on Saturday and determined the
problem to be a failure of the 54-year old actuator that controlled how open the
valve was. Although the valve was only half-open,all of the flow was processed
through the secondary system by allowing the peak flow to back up in the system
until the decrease in normal diumaI flow allowed the water to pass through the
valve. Backing up the incoming water prevented the need to bypass primary
effluent to the holding basins,averting a possible odorous condition.
On Sunday,May 22,2011,an actuator contractor,a contract mechanical team
from one of the capital jobs,and members of our maintenance crew were able to
remove the actuator and place the valve in a position approximately M open.
This allowed all flow to get to the seoondary system without backing up the
collection system. The maintenance crew anchored the valve in place using a
fabricated brad}ng system. Parts were located and shipped and repairs were
made on May 26.2011.
Replacement of the actuator is planned for in a capital project in which bids are
opening this June 1,2011. Replacement of the actuator will proceed as well as
replacement of C V22229,a similar valve that diverts primary effluent to the
lding basins. A spare actuator or spare parts will also be purchased. .a 1
7 a
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October 29, 2019 Special EOPS Committee Meeting Agenda Packet- Page 61 of 90
Page 4 of 5
FOLLOWING THE FAILURE
Evaluated and addressed the following under the Primary
Renovations, District Project (DP) 7285:
CV 22227 was replaced and included a new
modulating actuator.
New variable frequency drives (VFDs) and pumps
rebuilt for the Primary Effluent Pumps, including a
new back-up controller in the effluent channel that
allows pumps to operate with the CV 22227 fully
open or removed.
CV 22229 was evaluated and staff determined to
postpone replacement due to maintenance
completed and there is a second valve. (CV 22229 is
currently being replaced under the Mechanical and
Concrete Renovations, DP 7351.)
OTHER CONSIDERATIONS
Staff, with the assistance of HDR, Inc. and RMC,
considered:
Building a new second valve structure or channel to
have redundancy to CV 22227. This was very costly
and staff decided to invest in new VFDs, a valve,
and other work completed under DP 7285.
Adding a new structure or channel. This is planned
for the Primary expansion project and includes a 5t"
primary sedimentation tank to be evaluated in the
10-year Capital Plan.
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October 29, 2019 Special EOPS Committee Meeting Agenda Packet- Page 62 of 90
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WHERE WE ARE TODAY
BEFORE DP 7285:
• Primary pumps could not maintain level control in
the sedimentation tanks without CV 22227 due to
old mechanical drives and controllers.
• Unknown condition of CV 22227 and staff had never
taken the valve out.
AFTER DP 7285 (Today):
• Primary pumps can maintain level control in the
sedimentation tanks without CV 22227 due to new
VFDs and controllers. This has been tested.
• CV 22227 has been replaced and staff has the
ability to pull the valve out in case of failure.
QUESTIONS?
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October 29, 2019 Special EOPS Committee Meeting Agenda Packet- Page 63 of 90