Two above ground
oil storage tanks (No. 4 and No. 5 Light Oil Tanks) with associated pipelines and
one oil separation sump are to be demolished to provide space for installation
of the FGD plants. A land
contamination assessment was carried out at these areas to comply with the EIA
study brief's requirements. This
section briefly describes the land contamination assessment and makes a
reference to the Contamination Assessment Plan (CAP), Contamination Assessment
Report (CAR) and Remediation Action Plan (RAP) documents that were prepared
under this EIA Study.
2.2
Land Contamination Assessment
The land contamination
assessment was carried out following the methodology and procedures prescribed
in the contamination assessment plan (CAP) which made reference to EPD’s Practice
Note for Professional Persons (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 November 2005. A copy of CAP is
included as Annex A
of this report.
The land
contamination assessment included soil and groundwater sampling, laboratory
analyses for target parameters, preparation of contamination assessment report
(CAR) and preparation of remediation action plan (RAP). A copy of the RAP, which also includes
CAR as an appendix, is provided in Annex B
of this report.
The Site
Investigation (SI) for the land contamination assessment was conducted in the
area adjacent to the tanks and oil separation sump between 14 to 19 November
2005. The SI consisted of drilling
of six bore holes, soil sampling, installation of six groundwater sampling
wells at drilling locations, groundwater sampling, and laboratory analyses for
target parameters. The SI
programmed also incorporated a field and laboratory QA/QC programme to ensure
adequate sample results' quality. A
total of 15 soil samples and six groundwater samples (exclusive of QA/QC
samples) were collected from the Site areas for laboratory analysis of total
petroleum hydrocarbons (TPHs), polycyclic aromatic hydrocarbons (PAHs),
benzene, toluene, ethyl benzene and xylene.
2.3
Results and Recommendations
Total petroleum hydrocarbon (TPH)
was detected in one out of 15 soil samples and five out of six groundwater
samples at concentration exceeding the EPD Dutch B values for mineral oil and
implied a TPH contamination at the Site.
Remediation measures and procedures for TPH contamination were
recommended for the Site for the demolition operation, and the details are
provided in the RAP.
The excavated contaminated soil
will 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, May 1999. The remediation actions
could involve excavation, testing, on-site treatment (ie soil
venting/biopiling) and on-site reuse.
As groundwater is not used for either domestic or
industrial purposes at the Site and in the adjacent areas and taking into
consideration the absence of free-floating products and the relatively low
concentrations of TPH detected in the groundwater, remediation of TPH in the
groundwater of the Site is not considered necessary. Groundwater extraction is not anticipated
during the demolition and/or construction programmes as the proposed
excavations are at levels well above the site groundwater table. However, if groundwater is encountered
during the demolition and/or construction programmes and groundwater dewatering
from the work areas is required, the extracted groundwater will be collected,
appropriately stored on-site and recharged back to the underlying ground.
With the implementation of the remedial measures in
the RAP, the hazard and environmental impacts associated with the potential
land contamination and handling and treatment of the contaminated soil and
ground water are considered acceptable.