4.1
Desktop
study and site appraisal have been conducted during EIA study to identify
potential land contamination hotspots in the Study Area. Potential contaminated
areas identified include underground storage tank, aboveground storage tank,
two cremation rooms and the exposed areas around chimneys.
4.2
A
Contamination Assessment Plan (CAP) has been submitted and endorsed by EPD and
the site investigation (SI) was carried out in March 2008. The results indicate
that concentration of lead in a sample BH-1 exceeds the relevant Risk-Based
Remediation Goal (RBRG). The results and findings of site investigation are
presented in Contamination Assessment Report (CAR) and relevant remediation
measures are recommended in Remediation Action Plan (RAP).
4.3
The
remedial works will consist of excavating soil from an area of
4.4
Confirmatory
soil sampling and testing for closure assessment should be carried out
following the excavation at BH-1 to confirm the clean-up of contaminated soil.
One sample from the base of the excavation pit and four samples from the
side-wall should be collected for confirmatory testing. If the analytical
results of the confirmatory samples are below the relevant RBRG, removal of
contaminated soil can be considered complete. If the analytical results exceed
the relevant level, excavation should be extended further (with
Removal of
Underground Fuel Tank
4.5 During removal of the underground storage tank, appropriate precautions should be taken to avoid contamination. All fuel tank and associated pipelines should be emptied prior to any demolition work being undertaken. Any remaining sludge or sediment in the tanks or pipelines should be removed and disposed of as chemical waste in accordance with the appropriate regulation for disposal of such material.
4.6 After removal of the underground storage tank, confirmatory soil sample(s) underneath the tank should be collected and tested for Total Petroleum Hydrocarbons (TPH), volatile organic carbons (VOCs) and lead (Pb) using the same approach as mentioned in Section 4.4 above to ensure that no contamination due to fuel leakage.
4.7
As
the area around the existing pipeline was possessed by Civil Engineering and
Development Department (CEDD) for 10-Year Extended Landslip Preventive Measures
(LPM) Project, Phase 5, Package D – Landslip Preventive Works or Slopes in Hong
Kong Island project, access to the proposed trial pit location, TP-1, for
sampling could not be obtained during the SI. In addition, given the limited
space and burn hazard from the operating cremator for close inspection at two
cremation rooms, it was unable to access to the pipe joint or coupling where
their conditions or any signs of leakage were uncertain.
4.8
Further
site investigation for TP-1 shall be carried out prior to the demolition of the
existing crematorium according to the approved CAP. A supplementary CAP shall be prepared to
detail the sampling and testing plan for the cremation rooms before the site
investigation carrying out. Upon
completion of further site investigation, a supplementary CAR shall be prepared
to present the findings of the further site investigation for EPD’s
approval. If contamination is found, a
supplementary RAP shall be prepared and submitted to EPD and all contaminated
soils shall be treated prior to the commencement of any earthworks.
Mitigation Measures
during Construction Stage
4.9
Mitigation
measures have been recommended in the RAP for handling of the contaminated
materials during the course of site remediation in order to minimise (1) the
potentially adverse effects on the health and safety of construction workers
and (2) the environmental impacts arising from the handling of contaminated
materials. Regular site audit should be carried out to
ensure recommended environmental mitigation measures and health and safety
measures are implemented properly and effectively.
4.10 The following basic health and safety measures should be implemented as far as possible:
l Set up a list of safety measures for site workers;
l Provide written information and training on safety for site workers;
l Keep a log-book and plan showing the contaminated zones and clean zones;
l Maintain a hygienic working environment;
l Avoid dust generation;
l Provide face and respiratory protection gear to site workers;
l Provide personal protective clothing (e.g. chemical resistant jackboot, liquid tight gloves) to site workers; and
l Provide first aid training and materials to site workers.
4.11 The Contractor for the excavation works shall take note of the following points for excavation:
l Excavation profiles must be properly designed and executed;
l In case the soil to be excavated is situated beneath the groundwater table, it may be necessary to lower the groundwater table by installing well points or similar means. The discharge of groundwater, if any, should follow the requirements under the Water Pollution Control Ordinance (WPCO);
l Excavation zone should be fenced off;
l Quantities of soil to be excavated must be estimated;
l It may be necessary to split quantities of soil according to soil type, degree and nature of contamination;
l Temporary storage of soil at intermediate depot or on-site may be required. The storage site should include protection facilities for leaching into the ground e.g. a liner may be required;
l Supply of suitable clean backfill material is needed after excavation;
l Care must be taken of existing buildings and utilities; and
l Precautions must be taken to control of ground settlement.
4.12
The
following mitigation measures are recommended to be implemented during CS/S
processes.
Air Quality Impact
l The loading, unloading, handling, transfer or storage of cement should be carried out in an enclosed system.
l The loading, unloading, handling, transfer or storage of other materials which may generate airborne dust emissions such as untreated soil and oversize materials sorted out from the screening plant and stabilized soil stockpiled in the designated handling area, should be carried out in such a manner to prevent or minimise dust emissions. These materials should be adequately wetted prior to and during the loading, unloading and handling operations.
l All practicable measures should be taken to prevent or minimize the dust emission caused by vehicle movement.
Noise Impact
l The mixing area should be sited as far as practicable to nearby noise sensitive receivers.
l Simultaneous operation of mixing plants and other equipment should be avoided.
l Mixing process and other associated material handling activities should be properly scheduled to minimise potential cumulative noise impact on nearby noise sensitive receivers.
l Construction Noise Permit should be applied for the operation of powered mechanical equipment, if any, during restricted hours.
Water Quality Impact
l Stockpile of untreated soil should be covered as far as practicable to prevent the contaminated material from leaching out. The leachate should be discharged following the requirements of Water Protection Control Ordinance.
Waste
l
The oversize materials such as
rocks and boulders should be screened out, cleaned the soil attached and used
as filling material within the site.
Contaminated materials (soil or rock fragments) of size smaller than
l Stabilized soils should be broken into suitable size for backfilling or reuse on site.
l A high standard of housekeeping should be maintained within the mixing area.
l There should be clear and separated areas for stockpiling of untreated and treated materials.
4.13
The
implementation schedule of recommended land contamination mitigation measures
is presented in Appendix A.