7.1
Introduction
7.1.1
The proposed development
project for Yau Tong Bay, in addition to the major reclamation works, covers
the decommissioning of the existing ship building and repairing facilities at
the marine lots.
7.1.2
As part of the requirements in
the Environmental Impact Assessment Study Brief No. ESB-0010/1998 of the
captioned project, a land contamination impact assessment has to be conducted
for the site and a Remediation Action Plan (RAP) compiled if significant land
contamination is evident.
7.2
Land Use
History
7.2.1
The Yau Tong Marine Lots
include a variety of existing uses comprising shipyards, sawmills, timber
factories, concrete batching and motor repairs. There are also passive uses such as godowns
and building material storage. Some
of these operations are expected to have the potential to cause contamination
to the land due to the nature of their operations. As land contamination can be an on-going
process, a historical survey on the previous land uses is therefore
necessary. A number of information
sources such as existing owners and various governmental departments were
approached in an attempt to solicit information pertaining to the previous land
uses. Detailed landuse information
is contained in Section 2 and 3 of the Contamination Assessment Plan as
appeared in Appendix 7A.
7.3
Contamination Assessment Plan (CAP)
7.3.1
With reference to the
historical and current land use survey results and site inspection record,
detailed contamination assessment was deemed necessary for some 20 of the
marine lots. A CAP has been
prepared and submitted to EPD for endorsement. The CAP includes the methodologies of
the detailed site investigation (S.I.) works, involving sample collection and
laboratory analysis of soil and groundwater to detect if the sites were
contaminated and locations for sampling were also identified in the report. The
CAP has been endorsed by the Waste Policy and Services Group of the
Environmental Protection Department (EPD).
The endorsed report appears in Appendix 7A with a letter of endorsement
(EPD Ref.: (16) in EP 1/K15/YT/CDA/cc (VI) dated 29 April 1999) issued by EPD
which is included in Appendix 7B.
7.4
Detailed Site Investigation and Contamination Assessment Report
(CAR)
7.4.1
Detailed site investigation
works were conducted in accordance with the endorsed CAP. Soil and groundwater
samples were collected from 16 accessible marine lots, out of the 20 proposed
sites, for contamination analysis as described in the CAP.
7.4.2
The Dutch criteria for
contaminated soil (The Dutch List) and Risk Based Criteria for ground water
were used as the standard for assessment. The soil and groundwater analytical
results confirmed that a number of Yau Tong Marine Lots were largely
contaminated with petroleum hydrocarbons and heavy metals. High levels of PCBs and PAH were also
found in isolated locations. S.I.
results and contamination assessments were presented in the CAR. The CAR and RAP are integrated into one
report under the title of RAP. The
RAP is included in Appendix 7C.
7.5
Remediation Action Plan (RAP)
7.5.1
A site investigation for
contamination has been conducted in accordance with the approved CAP and
revealed moderate contamination of soil and groundwater at various marine lots
by TPH and metals as a results of previous industrial uses at the individual
lots. The results indicate that
contamination is localised and there appears no sign of migration of the
contaminants
7.5.2
Various remedial measures have
been recommended for the contaminated soils including excavation and
landfilling, bio-remediation by biopiling and solidification of soil.
7.5.3
The treatment technology
suggested is considered feasible and effective. A risk-based analysis of the groundwater
contamination suggested that only groundwater where free product is present
requires remediation. The total
volume of free product is estimated to be approximately six cubic metres.
7.5.4
It is suggested that the site
remediation shall be designed and supervised by competent personnel to ensure
that the clean-up is complete and satisfactory and poses no risk to the future
sensitive users of the Site.
7.6
Conclusion
7.6.1
A detailed land contamination
assessment for the site has been completed, in accordance with an endorsed
CAP. Remediation methods for
treating contaminated soil are proposed in the RAP and the developer should implement
the remediation procedures prior to commencement of any development
construction works. The site shall
only be considered suitable for further development after completion of the
proposed remediation works to the required standard.