9.1 In accordance with the EM&A Manual, monitoring of landfill gas is required for construction works within the Sai Tso Wan Landfill Consultation Zone during the construction phase. This section presents the results of landfill gas measurements performed by the Contractor. Appendix A shows the Limit Levels for the monitoring works.
9.2 The “Landfill Gas Monitoring Proposal”, including the monitoring programme and detailed actions, is submitted to the EPD for approval. Details of monitoring in this Proposal is in line with the monitoring requirements stipulated in the EM&A Manual.
9.3 Monitoring parameters for Landfill gas monitoring include Methane, Carbon dioxide and Oxygen.
9.4 According to the implementation schedule and recommended mitigation measures of the EM&A Manual, measurements of the following frequencies should be carried out:
Excavations deeper than 1m
at the ground surface before excavation commences;
immediately before any worker enters the excavation;
at the beginning of each working day for the entire period the excavation remains open; and
periodically throughout the working day whilst workers are in the excavation.
Excavations between 300mm and 1m deep
directly after the excavation has been completed; and
periodically whilst the excavation remains open.
For excavations less than 300mm deep
monitoring may be omitted, at the discretion of the Safety Officer or other appropriately qualified person
9.5 Monitoring of oxygen, methane and carbon dioxide was performed for excavations at 1m depth or more within the Consultation Zone. In this reporting month, the area required to be monitored for landfill gas are shown below and Figure 6 shows the landfill gas monitoring locations.
Ø Excavation Locations: Portion III
Ø Manholes and Chambers: N/A
Ø Relocation of monitoring wells: N/A
Ø Any other Confined Spaces: N/A
9.6 Table 9.1 summarizes the equipment employed by the Contractor for the landfill gas monitoring.
Model and Make
Portable gas detector
(Serial No. 137333)
9.7 In the reporting month, landfill gas monitoring was carried out by the Contractor at the aforesaid locations on 48 occasions. No Limit Level exceedance for landfill gas monitoring was recorded in the reporting month. The monitoring results are provided in Appendix R. Copies of calibration certificates are attached in Appendix B.