Operation Control Philosophy (OCP)
“Development Projects, Phase 4 Network and WWTP Capacity
Enhancement in Madinat Zayed”
Contract No. O-11542
Document No: O-11542-MZ-OCP-04
th
25
January 2016
Rev. No. 00
Concept Design, Process Description, O-11542-MZ -OCP-04-00
-0-
Revision No.
Date
Description
00
10/02/16
Operation Control Philosophy (OCP)
Project No.
: O-11542
Document No.
: O-11542-MZ-OCP-04
ILF Consulting Engineer
Signature:
……………………………….
Date:
……………………………….
Process Design Report, O-11542-MZ -OCP-04-00
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Table of Contents
S/No.
Description
Page
1.
Introduction
3
1.1
General
3
1.2
Design Conditions
3
1.3
Documents included by references
3
2.
Inlet Lifting Station & Basket Screen
4
3.
Headwork – Screening
5
4.
Headwork – Grit Removal
7
5.
Balancing Tank & Transfer Pumps
8
6.
Anoxic & Aeration Tanks
9
7.
Air Blowers
10
8.
Secondary Settling Tanks
11
9.
RAS/SAS Pumping Station
11
10.
Scum Pumping Station
12
11.
Tertiary Filtration
12
12.
Chlorine Contact Tanks & Dosing System
13
13.
Effluent Storage Tank & Pumping Station
13
14.
Aerobic Digester Tank & Blowers
14
15.
Odor Control System
16
16.
Generator
16
Process Design Report, O-11542-MZ -OCP-04-00
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1.0
INTRODUCTION
1.1 GENERAL
This document is a process control narrative for Madinat Zayed Waste Water
Treatment Plant, which describe the operation philosophy for process units including
Basket Screen, Inlet Lift Station, Headworks, Balancing Tank, Anoxic Tank, Aeration
Tank, Secondary Settling Tank, Tertiary Filtration, Chlorine Contact Tank, Treated
Effluent Storage Tank and Pump Station, Odor Control, (RAS/SAS) Pump Station,
Sludge Aerobic Digester, Sludge Drying Bed and Generator.
The objective of this document is to summarize the process control logic based on the
approved Process and Instrumentation Diagram (P&ID).
1.2 DESIGN CONDITIONS
The Sewage treatment plant for this project is an extended aeration system, the
extended aeration system is designed to be complete automated, requiring minimal
operator involvement, meeting ADSSC specifications and complaint with the effluent
discharge limits.
1.3 DOCUMENTS INCLUDED BY REFERENCE
This document must be used in conjunction with the following documents, which are
included by reference:
Document Number
Document Name
MZ-DSN-PD-02-00
Process Design Report
TD-MZ-STP-D-001
Process Flow Diagram
O-11542-STP-P-01
P&ID Symbols and Legends
O-11542-STP-P-02
P&ID Coarse Screen and Inlet Lift Station
O-11542-STP-P-03
P&ID Headwork (Package Unit)
O-11542-STP-P-04
P&ID Balancing Tank and Aeration tank
O-11542-STP-P-05
P&ID Aeration tank and Blower Building
O-11542-STP-P-06
P&ID Secondary Settlement tank
O-11542-STP-P-07
P&ID Disc Filter and Chlorine contact tank
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O-11542-STP-P-08
P&ID Effluent storage tank and Effluent Pumping Station
O-11542-STP-P-09
P&ID RAS/SAS & Scum pumping station
O-11542-STP-P-10
P&ID Aerobic Sludge Digester and Sludge drying beds
O-11542-STP-P-11
P&ID Disinfection Storage and Dosing system
O-11542-STP-P-12
P&ID Odor Control System for IHW and Sludge Storage
2. INLET LIFT STATION & BASKET SCREEN
Raw wastewater flows by gravity to a Basket screen (S-201) through the main manhole
(MH-1).
Which receive the flow from three streams:
1. From the future network connection
2. From domestic wastewater generation onsite and plant liquor returns (plant
drain such as reject etc…
3. From existing lift station.
The operation of the basket screen is manual and an electric hoist is provided to aid
the operator in lifting it up for cleaning.
Level switches are provided to protect the pumps with set-points as defined below.
Hydrostatic level controller is used to transmit the levels back to the SCADA and it is
used as primary protection for the pumps.
Level
High High
High
High Low
Low
Low Low
Set-Point
37.16 m
37.0 m
Function
Additional Condition
Alarm
Assist Pump Start
36.5 m Duty Pump Start &
Assist Pump stop
36.0 m
Duty Pump stop
35.5 m
Dry Run Protection
Hard-wired
Secondary flood protection to stop the inlet lift pumps if balancing tank or ATDC High
High level Switch is activated, is incorporated in the software as a soft stop, meaning
when the balancing tank or ATDC High High Level is cleared the Inlet lift Station will
resume normal operation.
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SCADA & HMI indication Alarm banner is shown when water reaches high high level in
both inlet lift station and either Balancing Tank or ATDC.
NRVs limit switch protection is hard wired to MCC to switch off to protect against low
flow. A flow meter, totalizer, and transmitter are provided to monitor and record the
flow from the inlet lift station to the headwork.
An alarm is to be generated by the PLC to show if any Duty/Standby Equipment is
running at the same time, whether it be in auto SCADA manual or Local.
3.
HEADWORK- SCREENING
Effluent from the lift station enters into two manual fine screens (MS-301 & MS-302)
(1 duty/1 standby) with 6mm perforated openings. During normal operation, both
screens will be in operation. Float Level switches are installed upstream (LSHH-301,
LSH-301 & LSL-301) (LSHH-302, LSH-302 & LSL-302) of the fine screens to measure
the level which initiates the cleaning cycle of the screens.
The Screw screen HSS-301 (main), will work on the maximum level and stop working
down the minimum level. The equipment can work with a timer but is advisable to
work by level; this will avoid work in excess. The washing of compacting area always
work if the HSS-301 when the machine is on. Manual screen (standby unit) starts
working when water overflows the automatic screen. The operator should do the
Cleaning manually.
The scum skimmer system (Classifier + blowers + skimmer), should work in a
continuous way when the SC-301 working.
The horizontal HGH-301 works temporized (2 minutes works) (10 minutes stops). This
time should be changed in function of the equipment performance.
The inclined HGI-301 works temporized (20 sec works) (5 minutes stops). This time
should be changed in function of the equipment performance.
This system will have one control panel that controls the full package of Main control
panel. The main control panel will control the screen, the bottom sand collector the
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classifier screw, and all the system for grease removal (blower and scrapper). If some of
the units fail an alarm will stop the system till the problem is solved.
MANUAL MODE:
All the single elements can be actuated manually. With this possibility the operator
can test all of the units and make work the system in a different way from the
automatic configuration mode. In manual mode operator is allowed to work the
machine when one of the components is out of order (i.e: if the screen is out of order,
water overflow through the manual screen and unit will work with grit and grease
removal units in manual until the repair of the screening unit)
AUTOMATIC MODE:
When operator sets the system in automatic control, the system will control the
complete sequence of start and stop of all the components. In case that the water
comes from the pump it controls the start with the confirmation of“pump running”.
If no signal then it works with timers and inlet level sensor.
 Equipment Screen
 Solenoid valve
 Signals Low Level
 High Level
 Alarm Level
 Motor Alarm
 Control
 Timer for delay of the stop T1
 Timer for the solenoid valve T2
The screen will start working when the level reach “high level” point. The machine
will start turning to remove the solids from the mesh and after time T2 the solenoid
valve will change into “open” status to wash the screening. When water level
decreases to “low level” the machine will stop after a time T1 to be sure that all
screenings in the screw are removed.
 Set points: Low level: must be set at the lower part of the mesh surface
 High level: must be set at the medium part of the tank and mesh area.
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 Alarm Level: Must be set before water overflows to the by-pass unit.
-
T1: 30 seconds delay
-
T2: 1m delay to start the washing system since screen is on.
4. HEADWORK - GRIT REMOVAL
Effluent from the fine screen flows by gravity to two grit removal units (HHG-301 &
HGG-302), (1 duty/1 standby). During normal operation, both units will be in
operation. The system is designed to separate the grit from organics in the
screened wastewater. The wastewater enters into a rectangular concrete tank.
Equipment

-
Blower
-
Classifier Screw (H/I)
-
Washer Drive
-
Solenoid valve
-
Motor Alarm scrapper
-
Motor Alarm for blower
Control

-
Timer for stop the grit classifier/skimmer after screen stops (T4)
-
Timer for blower (T5)
-
Timer for skimmer /classifier and solenoid valve (T6)
-
Timer for Washer and discharge screw (T7)
The system will follow always that screen is working and will stop with a delay of 15
minutes (T4) when screen stops (low level). Also this equipment will work with
timers, as maybe comes with few solids or level is low. Then the grease removal
system will work for 15 minutes every hour. This means that every hour the blower
will work 15 minutes (T5) and the skimmer/classifier will start with a delay of 20
seconds (T6) {opening solenoid valve} also for 15 minutes. The process also with
signal of level or timer will be. The blower will start up, after a time (T6) solenoid
valve will open the skimmer water unit and the scrapper will start to rotate. The
system will stop after time (T4). System of washer and discharge screw will start
after running of classifier and for time (T7) and it should be stop after 2 min of
stopping classifier (T4).
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5. BALANCING TANK AND TRANSFER PUMPS
Effluent from the Head works unit flows by gravity to a balancing tank. The main
function of the balancing tank is to dampen the varying inlet flow and provide a
constant flow to the downstream biological process. It will normally operate half
full allowing equalization of varying organic and hydraulic loads. Three soft starters
driven pumps (P-401A, P-401B & P-401C) will be provided to transfer the
wastewater to the anoxic tanks via Aeration distribution chamber (ATDC-401). The
pumps operate as 2 duty/1 standby with the primary control being flow paced via a
PD controller with adjustable set points at SCADA and a secondary level trim to
limit the number of start/stops due to varying inlet flow. The flow pacing and level
trim both have operator adjustable set points.
Flow pacing is achieved using the level trim with an Hydrostatic level (LIT-401)
installed in the balancing tank and Flow monitored via the magnetic flow meter
(FM-401) installed on pumps discharge header, this system is also protected with a
High level Switch (LSHH-401) alarm and soft stop for the upstream lift station stop
to prevent flooding of the balancing tank and a Low Level Switch (LSLL-402) Alarm
that also serve as dry run protection, wired directly to the pump starters. Both the
flow meters and the Hydrostatic level transmitter have fault signals.
The desired transfer flow rate is 625 m3/hr, The level trim becomes active at a
present High level set point increasing the PID flow set point by an adjustable
factor to overcome the rising level, when the level is reduced to the 50% mark the
flow pacing set point will resume its primary set point again. The same control
method is used for a low set point but by reducing the PID flow set point by
another factor until the 50% mark is reached in the balancing tank once again
resuming the primary flow pacing set point.
The balancing tank is designed to handle flow variations and it is not anticipated
during normal operation that all pumps will be operated at the same time.
There are also two air jet pumps (AJ-401A & AJ-401B) inside the balancing tank.
Their function is to provide aeration and mixing to the balancing tank, their
operation is continuous. There will be one Low level switch (LSL-401) hard wired to
protect the air jet pumps from running dry.
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The balancing tank area has ONE emergency stop push button at access point
connected to a common stop for all equipment in the balancing tank; (to protect
life) an alarm is also generated at SCADA to show the shutdown condition.
Shutdown is not re-settable from SCADA, only local at the Electrical room.
An alarm is to be generated by the PLC to show if any Duty/Standby equipment is
running at the same time, whether it be in auto SCADA manual or local
6. ANOXIC AND AERATION TANK
The equalized flow from the balancing tank is pumped to an aeration tank
distribution chamber (ATDC-401) and then by gravity to three anoxic tanks. The
function of the anoxic tank is to remove nitrates that will be generated in the
downstream aeration process. Each anoxic tank has one submersible mixer (MX402A, MX-402B & MX-402C) that run continuously to avoid sedimentation.
In order to achieve nitrate removal in the anoxic tank, two mixed liquor
recirculation pumps /Tank (P-402A & P-402B) (P-402C & P-402D) (P-402E & P402F) (1 duty/1 standby) are installed in each aeration tank. The operation of these
pumps is also continuous. The MLSS return Pump serves for re circulation of
activated sludge and formed nitrate to the anoxic treatment stage for controlled
de-nitrification. The MLSS stream is directed into the anoxic selector stage.
Under normal operation conditions the MLSS flow is a continuous stream without
any interruption.
The effluent from the anoxic tanks flows by gravity to three aeration tanks. The
aeration tanks are designed for an extended aeration process to remove
pollutants. Oxygen transfer into the wastewater and mixing is provided using air
blowers and fine bubble diffusers. To monitor the dissolved oxygen (DO) level (AIT401, AIT-402 & AIT-403) in aeration tanks, one DO probe is provided in each tank.
Each DO analyzer has a fault alarm and both have HH & LL alarm set points.
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7.
AIR BLOWERS
Three positive displacement air blowers (B-501, B-502 & B-503) (2 duty/1 standby)
with VFDs provide the air required for the aeration tank. The operation of the
blowers is controlled by a PID controller with adjustable set points at SCADA
(Default set point being for the DO is 2 ppm) with the PLC selecting the lower of the
3 DO analyzer values for use by the PID controller. If the 2 DO values drift apart
more than 10% then an alarm is generated for the DO analyzers to be calibrated, if
one of the DO analyzers fails the other DO analyzer value will be used by the PID
controller, if the 3 DO analyzers fail the PLC will swap to a timer control with
adjustable set points at SCADA.
The Aeration tanks have ONE emergency stop push button at each access point
connected to a common stop for all equipment associated with the Aeration tanks,
(to protect life) an alarm is also generated at SCADA to show the shutdown
condition. Shutdown is not re-settable from SCADA, only local at the Electrical
room.
An alarm is to be generated by the PLC to show if any duty/standby equipment is
running at the same time, whether it be in auto SCADA manual or local.
8.
SECONDARY SETTLING TANK
Wastewater flows by gravity from the aeration tanks to three Secondary settlement
tanks (TNK-601A, TNK-601B & TNK-601C) via the distribution chamber where the
sludge is allowed to settle and the supernatant overflows to the tertiary treatment.
The SSTs are equipped with rotating bridge (ME-601A, ME-601B & ME-601C) rake
mechanism which collects sludge to a central hopper. One drive motor is provided
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for each SST raking mechanism equipped with a protection Torque switch (ZS-601
& ZS-602) (ZS-603 & ZS-604) (ZS-605 & ZS-606).
The sludge will be raised up to the a collecting chamber and a motorized telescopic
valve (TV-602A, TV-602B & TV-602C) which transfer the accumulative sludge (by
adjustable percentage) to the (RAS/SAS) pump station wet well.
The rotating bridge also skims the surface scum into the scum Box which flows by
gravity to each of the SSTs scum manholes. The scum manholes are connected to
the plant wastewater collection network.
9.
RAS & SAS PUMPING STATION
Settled sludge flows by gravity from the three SSTs to (RAS/SAS) Pumping Station.
Three submersible pumps (P-901A, P-901B & P-901C) (2 duty/1 standby) are
provided in the (RAS/SAS) pumping station Working through variable speed drives
to discharge the return activated sludge (RAS) and surplus activated sludge (SAS).
The Pump station serves for recirculation of concentrated activated sludge
extracted from the secondary settling tanks to the activation system / anoxic
treatment stage for controlling de-nitrification and active biomass concentration.
The (RAS) stream is directed into the aeration tank distribution chamber (ATDC401) and (SAS) stream is directed to aerobic sludge digester.
(RAS/SAS) pumps operate as 2 duties /1 standby, RAS & SAS streams are provided
with flow meters to control pumps speed during the SAS discharge. The SAS
discharge operate on a fixed time during the day via a timer and run to transfer 350
m3/day and modulated valve provided to control the flow of (21.8 m3/hr) with 16
working hrs.
The (RAS) discharge operation is continuous and will provide flow of 150 % of
average flow (937.5 m3/h). The operation of the RAS pumps will continue until the
level drops to low level. In the event of duty (RAS/SAS) pump failure, the standby
pump will start to take over.
The (RAS/SAS) pumps will have Low Level switch (LSLL-901) hard wired to protect
the pumps from running dry and with High Level for indication/Alarm only (LSHH901).
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An alarm is to be generated by the PLC to show if any Duty/Standby equipment is
running at the same time, whether it be in auto SCADA manual or local.
One level transmitter (LIT-901) is provided for the control of the RAS/SAS pumps.
10.
SCUM PUMPING STATION
Scum collected from three SSTs will be collected by gravity to scum wet well, The
Scum pumps (P-902A & P-902B) (1 duty/1 standby) are running according to the
level in the wet well (hydrostatic level transmitter) (LIT-922) and in case of
transmitter failed the control will be through the float level switches (LSHH-921 &
LSLL-921).
11.
TERTIARY FILTRATION
Clarified effluent from the SSTs flows by gravity to three disc filters (F-701A, F-701B
& 701C), (2 duty/1 standby) for polishing through openings in the drums, and
passes through the filter media. Suspended solids are separated and accumulated
on the inside of the filter cloth. When water level inside the filter rotor increased to a
pre-set point, the filter rotor starts rotating and the backwash of the filter media
starts using the back wash pumps (P-701A, P-701B & P-701C). The high pressure
backwash spray removes the accumulated suspended solids into the reject flume
inside the filter. The suspended solids are then discharged via the reject pipe to
drain. The discs are submerged to approximately 65% and the water level of the
filtrate is kept by a level tank. Three level Switches (LSHH701A, LSH-701B) to
monitor high level pre disc filter. The clarified water enters the disc filter where
particles above 10microns are captured. The backwash pump is initiated when the
high level switch is reached. The backwash cycle is as per the manufactures
recommendations as is the drum and backwash pump protection (PSHH-701A,
PSLL-701A, PSLL-701C) and (PSHH-701B, PSLL-701B, PSLL-701C) High and Low
Pressure alarms.
12.
CHLORINE CONTACT TANK & DOSING SYSTEM
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Effluent from the disc filters flow by gravity to a chlorine contact tank. Disinfection
takes place in the chlorine contact tank using sodium hypochlorite. Two dosing
pumps (P-1101A, P-1101B) (1 duty/1 standby) provide the required dose. The
dosing rate of the pumps is controlled by a residual chlorine analyzer (AIT-703) via a
PID controller, the set point for the residual chlorine ranges from 0.5-1 ppm, the
chlorine analyzer has a fault alarm and HH & LL alarm set points. An Ultrasonic level
transmitter (LIT-1101) is installed in the sodium hypochlorite tank to provide
monitoring and a recorder reminder for the operators.
13.
EFFLUENT STORAGE TANK & PUMPING STATION
The disinfected water from the treatment plant flows by gravity to the TSE storage
Tanks consist of 2 partitions separated by manual isolation penstock (V-815) each
partition equipped with hydrostatic level transmitter (LIT-801 / LIT-803) to controls
the pumps via a PID controller with backup float switches (LS-802, LS-804) controls
the pumps via a PID controller with backup level switches (LSH0804, LSL0801) that
will be used to control the pumps in the event of LIT failure or if the operator
chooses to select float control at the SCADA , the float control operates in the
following manner, when the effluent in the storage tank reaches the High Level
Switch @ (4.0m) the duty pump will run until the level drops to the Low Level Switch
@ (0.6m). In the event of high flow or duty pump failure the standby pump will start
when the water level reaches the High Level Switch (LSHH0802) @ (2.15m) to take
over from the failed duty pump or to assist the duty pump as an emergency
measure only and both pumps will continue to run until the water level drops back
to Low Level Switch @ (0.6m), as a result of triggering the High Level Switch
(LSHH0802) @ (4.8), an alarm is also generated for the operator’s attention. All
alarm will also be generated if the water level reaches the Low Level Switch
(LSLL0801) @ (0.4m) this levels primary function is to serve as dry run protection,
wired directly to the pump starters. Each of the TSE pumps are also protected with
hard wired High and Low Pressure Switches (PISL0801, PISL0802).
There is an overflow at the effluent storage tank connected to the plant drainage
network to protect against flooding. (The plant drainage network gravitates to the
inlet lift station).
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There are two set of pumps connected to the final effluent storage tank. One set of
booster pumps (P1001, P1002,) (1 duty/1 standby) which provide service water to
the treatment plant and fire fi the booster set has its own pressure transmitter
(PIT1001) and pressure vessel (ET1001) to regulate the pumps on demand.
14.
AEROBIC DIGESTER TANK & BLOWERS
Surplus Activated Sludge (SAS) is directed to Aerobic Sludge Digester for further
aeration and thickening. The process achieved by the mean of injection air using air
blowers (B-1001A &B-1001B) (1 Duty/1 Standby) and settling of thickened sludge.
The operation of the air blowers is based on time, moreover the time of stopping of
blowers shall follow by running the thickened sludge transfer pumps to deliver the
thickened sludge to the drying beds, The supernatant water shall be transferred
through decanter with motorized valve to plant drain network, the residual sludge is
cyclically transferred to external sludge drying beds by a set of progress cavity
pumps (P-1001A & P-1001B) (1 duty/1 standby).
The operation of the DST pumps under the regulations of the Cycle Scheme is level
controlled according to the Aerobic Sludge Digester tank cycle. Also the flow
capacity is controlled by one MID flow meter per SDB feed line.
Sludge digester time line will be displayed on HMI to indicate the status of the
cycle. The timeline will show the current sequence of cycle as well as the remaining
time for the sequence in minutes.
Operation Schedule of Sludge Digester
Time Sequence of Aerobic Digester/Cycle - Total of 4 cycle / day each 6 hrs.
Event
Duration
Flow Rate/cycle
Fill / Aerate
Settle
4.0 hrs.
1.0 hr
21.87 m3/hr
-
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Sludge
Discharge
Decant
1.0 hr
35 m3/hr
73.5 m3/hr*
Total Flow
Rate/Day
350 m3/day
140 m3/day
-
294 m3/day*
* Based on 5 days operation in a week
Time sequence of Sludge Digester Tank
Time
Sequence
00:00 – 04:00
Fill/Aerate
04:00 – 05:00
Settle
05:00 – 06:00
Decant/Sludge Discharge
06:00 – 010:00
Fill/Aerate
10:00 – 11:00
Settle
11:00 – 12:00
Decant/Sludge Discharge
12:00 – 16:00
Fill/Aerate
16:00 – 17:00
Settle
17:00 – 18:00
Decant/Sludge Discharge
18:00 – 22:00
Fill/Aerate
22:00 – 23:00
Settle
23:00 – 24:00
Decant/Sludge Discharge
Cycle No. 01
Cycle No. 02
Cycle No. 03
Cycle No. 04
15. ODOR CONTROL SYSTEM
The odor control unit equipped with 2 Nos. extract fans for odor extract from the
inlet lift station, Headworks, Balancing Tank, Aeration Distribution Chamber and
aerobic sludge digester.
The fans shall be configured for a 1 Duty/1 Standby operation and shall run
continuously if the differential pressure blows the set point value.
A
control
panel
shall
be
provided
with
volt
Run/Fault/Available
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free
terminals
for
unit
Starter wired to Main PLC provided in the overall control station for remote
monitoring the system. The fans shall be controlled manually or in Auto mode
through a Hand-Off -Auto Push buttons.
The two fans shall be duty/standby and shall be logically operated in cyclic mode to
alter the duty/standby operation each 12 hr.
If the duty fan fails to start, the control system shall flag the fan as FAILED and the
Standby fan shall be started.
If duty fan fails to start due to high differential pressure the standby fan shall also
not start alarm signal shall be flagged. Fans shall be locally reset after clearing the
high differential pressure. If a duty fan is in an "Unavailable" state (isolated, in hand
or in fault) when the control. System calls it for operation the control system shall
start the standby fan. H2S sensor shall monitor the H2S concentration.
16. GENERATOR
A standby generator is provided to support all critical loads. The generator will be
controlled by an ATS (Automatic Transfer System) as per ADDC requirements.
The Standby generator will support the following equipment, as per the
Specification.

All Building Services Lights, Sockets and HVAC Equipment.

Control & Access, Telecom & Data.

Street& Local Outdoor Lighting.

The Main Control Room Equipment.

All PLC’s and Site Instrumentation.

All duty and /or assist equipment throughout the plant.

Complete Odor Control Unit.
All plant systems are allowed for on the Standby Generator in the same manner as
the Main supply.
Generator Fuel Transfer System
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Fuel from the diesel storage tank (ST1801) is pulled through the primary fuel filter
(F1801) by the fuel transfer pump (P1801) and then sent to the diesel daily tank
(ST1802). Fuel transfer pump is located in between the storage and the daily tank.
The fuel transfer pump is controlled and powered by a local control panel fed from
the generator Local control panel.
The fuel transfer pump has a check valve (CV1802) to prevent fuel flow back
through the fuel pump when the daily tank is full. The fuel transfer pump will start
when the daily tank reaches its low level (LSLL1802) at 150 mm. The fuel transfer
pump will stop either when the daily tank reaches its high level (LSHH1802) at
900mm or the bulk storage tank reaches its low level (LSLL1801) at 150 mm. A bund
High level switch (LSHH1803) is installed to give an Alarm to SCADA and locally via
a sounder to warning the tanker driver of an overflow condition.
For maintenance purposes, there is two ball valves one upstream and one
downstream the fuel transfer pump in case of pump failure.
Process Design Report, O-11542-MZ -OCP-04-00
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