 The
Sungai Selangor Phase 3 Water Works is located to the south of the
existing Phase 2 Treatment Works. It is implemented in two stages,
Stage 1 and Stage 2, which operates independently each with a nominal
work output of 400MLD.
The water treatment structures for each stage include an aerator,
a chemical mixing chamber, clarification tanks, filters, chlorine
contact tanks and clear water tanks. There is also a chemical building,
chlorine building, administration building, wash water and sludge
disposal works, and all associated roads and services.
The raw water is extracted from the river intake located upstream
of the existing Phase 1 and Phase 2 river intakes, on the left bank
of Sg. Selangor. It is pumped to the treatment inlet and discharged
over a weir into a cascaded aerator; at the outlet of the aerator,
the water is dosed for pre-chlorination and then passed on to the
chemical mixing chamber where it is dosed for coagulation and flocculation.
The conditioned water is passed through the clarifiers and the rapid
gravity filters. Chlorine and fluoride are added before the treated
water flows into the clear water tanks.
Sludge from the clarifiers flows to the thickening tanks via a
holding tank. Filter waste wash water is collected in wash water
recovery tanks; the supernatant is returned to the works inlet and
the sludge pumped to the thickening tanks again where the sludge
is mixed with the clarifier sludge. Facilities are provided for
the thickening tank supernatant to be discharged into the overflow
system. There is also a mechanical dewatering of the thickened sludge
from the thickening tanks. The thickened sludge from the thickening
tanks is pumped directly to the sludge lagoons.
The plant is designed such that the treatment works is operated
with minimum personnel. All preparation of chemicals for use during
the next 24 hours is carried out during the 8 hour day shift. Routine
plant maintenance is generally carried out on weekdays in the daytime.
The plant is capable of unmanned operation at all other times under
normal operating conditions. in the event of failure of the duty
dosing plant, the standby plant operates automatically to take over
the functions of the failed duty plant.
There is a Command Centre in the Administration Building; facilities
are provided there for monitoring the operation of the pumping stations
and the water treatment works. Facilities are also provided for
the control of the raw water and treated water pumps, selected valves
and penstocks, chemical dosing, etc.
The scope of works covers the supply, installation, testing and
commissioning of the instrumentation systems. The installation includes
the following: -
Intake
- Supply, install and commission all instruments for the Intake
Works.
Treatment
- Supply, install, connect, test, calibrate and commission all
instrument measurements of levels, pressures, flows and water
quality throughout the treatment works for display on the local
control panels and also in the Command Centre of the Administration
Building.
- Design, install, connect, test, calibrate and commission instrumentation
panels in the treatment plant.
- Supply spare parts and consumables for the entire installation.
- All associated cabling and connections.
Balancing Reservoir
- Supply, install, test, calibrate and commission all instrument
measurements of levels and flows through radio-link telemetry
system for display on CitectCitectSCADA system in Command Centre
of the Administration Building.
- All associated cabling and connections.
The CitectSCADA system consists of 3 main locations - Intake Works,
Treatment Works and Bukit Tadun Balancing Reservoir. These locations
are linked by redundant radio telemetry system.
The PLC-based Outstations (O/S) transmit all process data, events,
alarms and commands to the CitectSCADA server and further shared
among all the other operator MMIs and engineering workstations.
The PLC-based intelligent outstations perform the role of local
controller units for the plant sequential control functions. All
CitectSCADA nodes and PLC control nodes are linked to the same backbone
to ensure data integrity as well as providing a platform to make
possible scalable architecture features i.e. scalable from existing
system size up to possible expansion of system in stage 2 (future).
The redundant CitectSCADA nodes (Data Server) can also serve as
one of the main operators MMI or engineering stations.
The complete integrated CitectSCADA system is built around 100Mbit/s
Ethernet ring redundancy fibre optic backbone that accomodates 100%
redundancy in inter-equipment communications.
The computer terminals and all outstations are provided with backup
power supply through Uninterruptible Power Supply (UPS) systems.
The battery banks are capable of providing backup power to the master
station equipment for 4 hours while the remaining outstations have
3 hours of backup power after loss of incoming power supply.
The CitectSCADA system is able to adjust all set points and timers
in the local PLCs or upload new programs into them, if necessary.
Local Control Panels (LCP) and Supervisory Panels house the outstations
and perform the automatic sequence control functions for the processes
that these LCPs or Supervisory Panels are designed for.
The whole CitectSCADA system is designed such that with the loss
of the host computers or sub-master stations, it does not impair
the efficiency of the system to carry out the local automatic and
sequence controls via these LCPs or Supervisory Panels. |
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