7.1
Introduction
Demolition or
relocation of a number of existing facilities will be required to accommodate
the proposed emissions control facilities.
These existing facilities include:
·
the
CPB Fuel Oil Day Tank (FODT) and associated pipe works connecting with fuel oil
pump house (FOPH) and oil interceptor;
·
the
Dangerous Goods (DG) stores; and
·
the Intermediate
Pressure Reduction Station (IPRS), LPG compound and CO2 storage
tanks.
The existing
facilities indicated above were identified as potential sources of
contamination following a walkthrough of the Project Areas on 16 November
2005. A land contamination
assessment was conducted in accordance with the requirements of the Study Brief. This section describes the land
contamination assessment and makes reference to the Contamination Assessment
Plan (CAP), Contamination Assessment Report (CAR) and Remediation Action Plan
(RAP) that were prepared.
7.2
Legislative Requirements and Evaluation
Criteria
The land contamination assessment was carried out following the
methodology and procedures prescribed in the CAP, which made reference to the
following documents published by EPD:
·
Practice Note for Professional Persons:
Contaminated Land Assessment and Remediation (ProPECC PN
3/94); and
·
Guidance Notes for Investigation and
Remediation Contaminated Site of Petrol Filling Stations, Boatyard and Car
Repair/Dismantling Workshops.
The CAP was approved
by the EPD in April 2006. A copy of
the approved CAP is included in Annex E.
7.3
Land Contamination Assessment
7.3.1
Site Investigation Programme
The land contamination assessment included soil and groundwater sampling,
laboratory analyses for target parameters, preparation of the CAR and
preparation of the RAP. A copy of
the CAR and the RAP is provided in Annex
E.
The Site Investigation (SI) for the land contamination assessment was
conducted within the Project Areas and comprised the following:
·
manual
excavation and soil sampling at four trial pits (TP1 to TP4); and
·
soil
boring by rotary drilling and sampling at eight locations (DH1 to DH8).
The SI programme also incorporated a field and laboratory quality assurance/quality
control (QA/QC) programme. A total
of eight soil samples and eight groundwater samples (exclusive of QA/QC
samples) were collected from the Project Areas for laboratory analysis of total
petroleum hydrocarbons (TPHs), polycyclic aromatic hydrocarbons (PAHs),
benzene, toluene, ethyl benzene and xylene (BTEX), volatile organic compounds
(VOCs) and semi-volatile organic compounds (SVOCs).
7.3.2
Site Investigation Results
The concentration of
TPHs, including light diesel (C10-C14), heavy diesel (C15-C28) and heavy oil
(C29-C36) fractions, in the soil sample collected at location TP3 and at 0.9 m
below ground level (bgl) exceeded the Dutch “B” value but was below the Dutch
“C” value. No TPH contamination was
detected in the soil collected from other sampling locations and therefore the
contamination observed at TP3 was considered to be localised.
TPH (light diesel,
heavy diesel and heavy oil) contamination at above Dutch “B” and “C” levels has
been reported in all the groundwater samples (DH1 to DH8). The TPH concentrations detected in the
groundwater samples from DH1 and DH2 were primarily attributable to the light
diesel and heavy diesel fractions.
TPH concentrations at DH3 to DH8 were primarily attributable to the
heavy diesel and heavy oil fractions.
These TPH findings are all located on a well-established reclaimed area
of CPB, which is far from sensitive use.
7.4
Remedial Measures
Under the current
engineering design, the level of the area in which TPH contamination in soil
has been identified will need to be raised by filling to the same level as the
surrounding ground and major excavation is not envisaged. Any excavated contaminated soil should
be remediated in accordance with the EPD’s Guidance
Notes for Investigation and Remediation of Contaminated Sites of Petrol Filling
Stations Boatyards, and Car/Repair/Dismantling Workshops. Details of the remediation measures and
procedures for TPH soil contamination recommended for the Site are provided in
the RAP.
As groundwater is not
abstracted for either domestic or industrial use at the Site and in the
adjacent areas and taking into consideration the absence of free-floating
products, human exposure to the contaminated groundwater may only occur during
the construction of foundations for the emissions control facilities, eg
excavation for the construction of bored piles. If groundwater is encountered during the
construction works and removal of groundwater from the work areas is required,
the groundwater should be collected and recharged back to the underlying ground.
7.5
Summary and Conclusion
With the implementation of
the remedial measures in the RAP, the hazards and environmental impacts
associated with the potential land and groundwater contamination are considered
to be low.