LANDFILL MANAGEMENT

BTSL is operated and maintained by an experienced team with a full range of trucks, compactors and earth moving plant at its disposal. The operations team works on three shifts, seven days a week.

BTSL operation features 24-hour security patrols and screens all incoming waste trucks at the security check point.

It incorporates a smart-card system for vehicle identification and data logging at weighbridges.
The designated tipping platforms for waste disposal are planned and executed on a daily basis. Specialised compactors are used in the application of daily earth cover to maintain hygience, prevent odour and achieve maximum air capacity.

An on-going comprehensive training program is in place to train the team to ensure optimum standards are maintained constantly. This includes regular briefing and trial runs on safety and emergency procedures. A fully trained team is dedicated to manage the leachate treatment plant, which operates round the clock.

Environmental Consideration

  • BTSL has a complete environment protection system based on implementation of the following system components:
    • Surface water management plan
    • Leachate management plan
    • Environmental monitoring
    • Early warning and emergency containment system

Leachate Treatment Plant

A state-of-the-art leachate treatment plant is in place to treat leachate output from the landfill. The plant is based primarily on biological reaction with a series of chemical dosing to achieve the required leachate treatment standards. It is equipped with 8 sequential batch reactor (SBR) lagoons, 48 aerators, chemical storage and dosing system, balancing tanks, sludge thickener and a dissolved air flotation plant. The SCADA system controls all the pumps and valves, enabling the plant to operate automatically. The plant has a treatment capacity in excess of 2,000 cubic meters per day for methanogenic leachate.

Treated leachate is conveyed to the reed beds for final polishing. The reed beds consist of Phragmites plant capable of absorbing residues in the treated leachate to further improve its quality. BTSL is the pioneer in the region in using the reed beds polishing process.

4 leachate holding-ponds on site provide 180,000 cubic meters leachate storage capacity to attenuate peak flows during wet seasons. The holding ponds also provide leachate storage when the leachate treatment plant is undergoing maintenance.

Effective leachate management is a crucial part of tropical landfill operation. BTSL monitors leachate production, storage and treatment rates closely through its proprietary leachate management system to determine current and future storage and treatment requirements.

BTSL maintains 4 anaerobic leachate holding-ponds for storage and pre-treatment of raw leachate. A large holding capacity provides a fail-safe system, allowing excess leachate storage in wet season when leachate production may exceed the treatment rate.

The leachate management system provides early warning and enables pre-emptive action to address storage requirements. It also helps operators determine the timing for future upgrade of the leachate treatment plant.

Surface Water Management System

Surface or storm water run-off is diverted away from active landfill cells and channelled through surface drains toward open water-courses, silt traps and detention ponds.

Earth cover is applied daily over compacted waste in the cell to prevent infiltration of rain water into the leachate collection system and avoid formation of excess leachate.

Regular desilting of the silt traps are carried out to maintain surface water quality.

Treated Effluent Management

BTSL employs a zero-discharge policy on treated effluent. Treated effluent, which has reached environmental standards allowing discharge into open water-courses, are irrigated in a 120-acre field instead of discharging into open water-courses.

This allows the treated effluent to be absorbed through evapotranspiration and soil moisture retention, promoting optimum protection to the environment.

Leachate Quality Test

Daily, weekly and fortnightly tests are carried out to obtain different parameters of both raw and treated leachate. This provides regular review of raw leachate characteristics over time, and changes in quality of treated effluent as treatment regime progresses.

Daily Treated Effluent Tests
Daily tests on treated leachate are carried out at the SBR lagoons to ensure successful treatment. Based on the tests, treatment rate and strategy can be adjusted for subsequent treatment cycles. Daily tests are conducted to obtain readings for: pH, Ammoniacal nitrogen, Nitrates, Nitrites, and Dissolved oxygen.

Weekly Treated Leachate Tests in SBR Lagoons and Reed Beds
Weekly treated effluent tests are carried out at the treated leachate-balancing tank (TLBT) and irrigation discharge chamber (IDC) to assess long-term effectiveness of the SBR lagoons and reed beds.

Fortnightly Raw and Treated Leachate Tests
Raw and treated leachate are sent to independent laboratories fortnightly for extensive testing. The result is submitted as part of the Environment Monitoring Report and used for long-term study of leachate characteristics progression. These samples are taken at all raw leachate holding ponds and treated leachate chambers.

Environmental Monitoring

Surface water and groundwater quality monitoring tests are carried out monthly at BTSL. Nitrites, pH, ammonia, e-coli, suspended solids and trace metals are among the major parameters tested.

Other Monitoring Requirements
Ambient air quality and noise levels are monitored quarterly for submission to the Department of Environment in the Quarterly Environment Monitoring Report. These reports also contain the closely monitored parameters stated above.

 

Emergency Containment System

BTSL is equipped with an emergency response system and leachate containment bund to prevent accidental leachate break-out into external water-courses. Leachate is held within the bund to enable remedial works to be undertaken. This safety measure surpasses the requirement of the Department of Environment, and includes the following components:

    • Flow meter at monitoring bund
    • Detention dam for upper catchment
    • Containment bund at leachate treatment plant and holding ponds

Monitoring Bund

The monitoring bund is also a detention dam to detain contaminated flow detected by the flow meter and water quality instruments. Contaminated water is returned to the raw leachate holding ponds for further treatment at the monitoring bund pump chamber.

Containment Bund
The bund has a containment capacity of 100,000 cubic meters. It is operated by gate valve for isolation in the event of accidental spillage or breach of raw leachate.