The effective management of land contamination during the construction phase will be monitored through the site audit programme.
Potential impacts associated with the handling, storage and disposal of contaminated soils and groundwater, through not expected, can be mitigated by adopting the following measures:
· The use of bulk earth-moving excavator equipment should minimise the potential interface of contaminated materials with construction workers;
· Exposure to any contaminated materials should be minimised by the wearing of appropriate clothing and personal protective gear such as gloves (when interacting directly with contaminated material), providing adequate hygiene and washing facilities, and preventing smoking and eating during such activities;
· Where excavated material is suspected to be contaminated, preliminary analysis of representative samples should be performed to enable options for disposal of contaminated materials to be properly evaluated (based on soil classification) and to allow the volume of such materials to be estimated before agreement or approval is sought from the relevant authorities;
· Vehicles containing contaminated materials should be suitably covered to limit potential dust emissions or contaminated wastewater runoff, and truck bodies and tailgates should be sealed to prevent any discharge during transport or during wet conditions;
· Contaminated soils should not be stockpiled on site. However, in the event that this is necessary in the short-term, any stockpiled contaminated sediments should be covered with plastic sheeting or tarpaulin, especially during heavy rainstorms;
· Only licensed waste hauliers should be used to collect and transport contaminated material to an appropriate disposal site and procedures should be developed to ensure that illegal disposal of wastes does not occur;
· Prior agreement should be sought with the appropriate authorities regarding the acceptability of disposal of contaminated sediments to East Sha Chau Marine Borrow Area or to landfill, following any sampling and analysis programme conducted. Although, not officially designated, the only landfill in Hong Kong that is likely to be able to accept small amounts of contaminated sediments is the WENT landfill;
· The necessary waste disposal permits should be obtained from the appropriate authorities, in accordance with the Waste Disposal Ordinance (Cap 354), Waste Disposal (Chemical Waste)(General) Regulation (Cap 354), as required;
· Records of the quantities of wastes generated and disposed of should be maintained;
· In accordance with good construction practice, silt traps should be used to reduce the impact to drainage caused by suspended solids (SS) arising from the disturbed ground, or any construction materials such as cement and gravel. Groundwater should be disposed of in accordance with the Water Pollution Control Ordinance (WPCO);and,
· Surface waters should be diverted around any areas currently being worked, or materials being stockpiled, to minimise potential runoff into excavations, as runoff would increase the volume of contaminated groundwater requiring disposal and suspended solids in the wastewater stream.