Trinidad and Tobago - Water treatment plants

Description

The Water and Sewerage Authority (WASA) of Trinidad and Tobago has initiated a series of new projects aimed at improving the quality and supply of treated water in Trinidad and Tobago. 

The two proposed site areas are Santa Cruz (Green Meadows) and Goldsborough, Tobago.

The contractor would be required to mobilise and execute full construction works over a project timeline of 18 months.

The works shall include all labour, equipment and material for the design, supply, construction, installation, connection, testing and commissioning for the functional operation of all the works in the contract.

A PLC driven control system must be developed and fully integrated with all instrumentation and intelligent devices such that the facility is fully automated and capable of operation from an Operator workstation.

The PLC system must support communication protocols that will allow integration of data from the PLC into WASA overall SCADA network. The authority recommends a PLC that supports OPC UA, MODBUS TCP and MQTT protocols for this purpose.

Detailed scope of works

The design consists of but is not limited to the following components:

• design, supply, and installation of a fully automated package water treatment plant and equipment, inclusive of all civil, processes, mechanical, electrical, controls and Instrumentation requirements.
• testing and commissioning
• supply of 4 copies of O&M manuals
• “as built” drawings for interconnecting pipework, appurtenances and equipment supplied
• supply and install communication network from Goldsborough WTP to WASA Head Office OCC (Operation Control Centre) and Tobago OCC

Performance specification for the treatment plant

Treatment process

The process units to be incorporated into the new Goldsborough water treatment plant shall include the following at a minimum:

• raw water screening and extraction
• coagulation/flocculation
• clarification
• filtration
• disinfection
• chemical dosing system
• sludge management system

Design and construction requirements

The raw water intake shall include but not be limited to the following.

The design, supply and construction of:

• an appropriately designed weir with washout valves
• a raw water intake upstream of the weir inclusive of raw water screening system and screen washing appurtenances. The design capacity of the intake shall be 2.0 IMGD
• a sub-structure and sump which will allow for efficient abstraction during the dry season (1.0 IMGD)
• suitable access (pathways, ladders, manholes) to clean raw water intake screen and pump sump

The design, supply and installation of:

• 2 or more pumps (duty/standby arrangement-to ensure 100% design capacity when one duty pump is defective) to extract the 2.0 IMGD of raw water needed for the package plant’s operation. The raw water pumps should be designed with VFDs and all the necessary protection devices inclusive of remote sensors, temperature and vibration
• security lighting placed around the perimeter of the intake and pumping equipment
• a new electrical and starter building for raw water intake. The electrical system shall be designed with the appropriate amount of standby capacity
• a raw water transmission system of the appropriate pipe size terminating with a valve at the inlet to the treatment plant
• an appropriately sized electromagnetic-flow meter to be installed on the raw water pipe discharge main
• a security fence (inclusive of gates) around the perimeter of the intake
• an access roadway to the intake

Considerations of annual flooding shall be considered when designing the raw water intake, height of the electrical/starter building and the choice of raw water pumps.

The works to the treatment plant shall include but not be limited to the following:

• site works inclusive of clearing, grubbing, grading and backfilling.
• design, supply and construction of an appropriately sized foundation to accommodate the package water treatment plant
• design, supply and installation of a fully automated package water treatment plant consisting of two or more trains capable of producing a combined total production of 2.0
• testing and commissioning of the raw water intake and water treatment plant

IMGD, the plant shall include of all required pumping systems (effluent, backwash, sludgetransfer) and equipment (compressors, starters, chemical dosing equipment).

The package treatment plant shall include appropriate modules to ensure final water qualitymeets or exceeds WHO drinking water standards. The Plant will be designed forturbidity spikes which may occur during flooding events.

The plant must have appropriate physical and chemical treatment processes and should employ the latest technologies and worldwide industrial best practices for potable water.

This includes the design, supply and construction of a new clear-well and all mechanical works, inclusive but not limited to the following:

• pipelines, valves, fittings and appurtenances required to interconnect all processes and equipment from the raw water intake to the water treatment plant and clearwell
• interconnecting pipework and valves between each train inclusive of all chemical lines and all other necessary process line to commission the plant
• interconnecting pipework and valves to the High Lift Pumping Station
• treated water discharge header (inclusive of an electromagnetic flow meter), terminating with a valve and blank flange at the perimeter fencing of the WTP

Design, supply and construction of:

• post-treatment facility for pH correction
• chlorine storage and dosing facility inclusive of chlorine dosing equipment
• a chemical building for the storage and mixing of chemicals

Design, supply and installation of a system for monitoring water quality parameters, including, but not limited to the following where applicable:

• pH
• turbidity
• chlorine residual
• iron
• colour

All readings must be integrated with the PLC and control system to allow remote monitoring ofthe water quality and automatic shutdown of the intake/facility in the event that the raw waterquality is unacceptable.

Design, supply and construction of:

• a sludge pond/sludge handling facility to treat sludge from the water treatment plant and backwash water from the treatment process
• permanent access roads to site, intake and sludge pond and inclusive of associated drainage system
• structures and site work within the WTP site including but not limited to building, roads, surface water drainage, water supply, sewerage, and perimeter fencing
• all electrical works required to ensure full functionality of all the equipment at the Raw Water Intake and Water Treatment Plant (inclusive of starters and all associated electrical works for the effluent pumps, backwash pumps and sludge transfer pumps, chemical dosing pumps, mechanical mixers and air blowers)
• a treated water pumping station with a design capacity of 2.0 IMGD

Design, supply and installation of: 

• a new lighting system to ensure adequate visibility throughout the entire raw water intake, water treatment plant and connecting roadways
• a power supply, including protection and standby power generation, with capacity to operate the entire site including raw and treated water transmission facilities

Opportunity closing date

18 December 2023

Value of contract

to be confirmed

The buyer is happy to talk to

manufacturers, wholesalers, distributors, agents, consultants