6.1.1
Based on the tentative Project
programme, the Existing Crematorium will be decommissioned and demolished
within the period of October 2006 to November 2007. Since the Existing Crematorium is a registered pathological incinerator,
its decommissioning is classified as a Designated Project under EIAO Schedule 2 Part II (Item 3).
6.1.2
Scott Wilson Limited was commissioned
by the HKPC as a sub-consultant to carry out an assessment of land
contamination at the site of the Diamond Hill Crematorium.
6.1.3
The Contaminated Land Assessment has
been carried out in accordance with the guidance given in the following
documents:
·
Annex 19 of the Environmental Impact
Assessment Ordinance – Technical Memorandum
·
Practical
Note for Professional Persons (ProPECC) Note PN
3/94, “Contaminated Land Assessment and
Remediation”
·
“Guidance
Notes for Investigation and Remediation of Contaminated Sites of Petrol Filling
Stations, Boatyards and Car Repair/Dismantling Workshops”, Environmental Protection
Department, EPD/TR1/99.
6.1.4
A Contamination Assessment Plan (CAP)
has been prepared and endorsed by EPD.
This report is included as Appendix C1. The objectives of the CAP are to:
·
Determine the previous landuses of the
site
·
Outline the current environmental
setting of the site, in terms of surrounding landuses, geology and hydrogeology
·
Describe the processes carried out at
the site
·
Identify potential sources of ground
contamination
·
Outline potential contaminant sources,
receptors, and the potential pathways between sources and receptors
·
Determine a suitable site
investigation strategy to identify, quantify and delineate areas of ground
contamination
6.1.5
Site investigation works were carried
out in March 2003, and the results are documented in the Contamination
Assessment Report (CAR) and Remediation Action Plan (RAP) as attached in
Appendix C2. The objectives of the
CAR and RAP are to:
·
Present
the findings of the site investigation
·
Assess
the concentrations of contaminants found against relevant criteria
·
Determine
the requirement for any remedial works
·
Specify
the extent and nature of remedial works
6.1.6
Summaries of findings in CAP, CAR and
RAP are given below.
6.2.1
The geology of this part of Kowloon
comprises Quaternary colluvial (debris flow) deposits of the Fanling Formation,
overlying granite bedrock of the Kowloon Granite Formation.
6.2.2
Ground conditions of the project site
were found to consist of sandy fill material with rock fragments, to depths of
up to 2m below ground level, overlying completely decomposed medium grained
granite or colluvium.
6.2.3
A watercourse is present immediately
to the east of the site, which consists of a natural rocky channel. Immediately to the south of the site,
this watercourse passes into an underground drainage channel, prior to
ultimately discharging into Victoria Harbour. However, during site investigation, no groundwater was
encountered.
6.3.1
The site is currently used as a
crematorium, and consists of a central building for carrying out services and
cremationsand a number of smaller
structures such as stores and a CLP secondary substation. The grounds of the site are landscaped
with many trees and shrubs.
6.4.1
The site is bounded to the north and
east by cemeteries and grave sites, with Hammer Hill Road also lying to the
east of the site. There are a
number of buildings to the west, which include a columbarium for cremated
remains and a CLP secondary substation.
Above ground high-voltage electricity cables are situated to the north
of the site. Po Kong Village Road
runs along the southwestern edge of the site. Tate’s Cairn Tunnel passes beneath the area, to the north
and west of the site boundary.
6.5.1
Historical landuses have been determined
by examination of historical aerial photographs and site plans and by
interviews with current employees.
6.5.2
A total of six historical aerial
photographs have been reviewed, as listed below:
·
81A/177, April 1949;
·
1935 Y72, 1972;
·
14304, June 1976;
·
A18296, September 1989;
·
A35622, July 1993;
·
CN23166, June 1999.
6.5.3
The earliest aerial photo indicates
that the site was, at this time, predominantly grassed, boulder-strewn
hillside. A number of tracks
crossed the site, and the photograph suggests that graves were present to the
west and north.
6.5.4
By the time of the 1972 photo, the
area of graves had spread southwards, over part of the current crematorium
site. The area to the southwest of
the site (outside the current site boundary) appears to have been used as a car
dismantling and repair facility.
There were a number of buildings in the southeastern corner of the site,
comprising the previous Diamond Hill Crematorium and the associated staff
accommodation. The 1976 photo
shows the vehicles to the southwest had been removed, and construction work
appeared to be underway. There is
an area in the southwest of the current site which consisted of
irregular-shaped plots of land, and may represent a squatter area or small
agricultural plots.
6.5.5
Construction of the current
crematorium took place between the photos of 1976 and 1989 were taken. Many of the grave plots shown in
earlier photos were covered by the new crematorium development, and the
structures in the southeastern corner of the site were also removed. The basic layout of the crematorium in
the 1989 photo was the same as at present. A large new building is also shown to the northwest of the
site. The layout of the area does
not appear to have altered significantly between the 1989 photo and the most recent
photo of 1999.
6.5.6
A number of drawings have been
provided by Arch SD, dating from the construction of the present crematorium in
1977/78. These drawings indicate
the locations of the previous crematorium, the underground fuel storage tank,
and the dangerous goods store. The
drawings indicate that considerable earthworks and disturbance of the natural
topography should have occurred during these construction works.
6.6.1
A site inspection was carried out on
21st November 2002. The locations
of the dangerous goods store, underground fuel tank and CLP secondary
substation were confirmed, although access to the interior of these buildings
was not available. No visible
evidence of contamination was noted during this site visit. A further site visit was undertaken on
11th December 2002, when access to all areas (excluding the CLP secondary
substation) was possible. Site operatives were present during the site visits
and provided verbal information on current and previous site practices. This information has been taken account
of in determining the likely sources of contamination.
6.7.1
On the basis of a review of historical
information and current practices, and following the site inspection, the
principal potential sources of contamination at the site were identified. These are associated with the site’s
current and former use as a crematorium.
Other land uses within and beyond the site boundary are considered
unlikely to give rise to significant contamination within the site. The locations of potential contaminant
sources are shown in Figure 6.1.
6.7.2
Facilities or activities which may
result in contamination, and the contaminants which may be present, are listed
below.
Fuel
Storage Tank
|
Potential Contaminants:
|
Total Petroleum hydrocarbons (diesel range) (TPH);
Polyaromatic hydrocarbons (PAH).
|
The fuel tank has been used for storage of diesel rather than
petrol, so lighter range petroleum fractions (e.g. BTEX) are not likely to be
present. An underground fuel
pipe is believed to lead from the main buried tank to a small tank inside the
main building, in the roof space.
The exact alignment of this pipe could not be precisely determined
either from the available plans or from the site visit.
|
Dangerous Goods Store
|
Potential Contaminants:
|
Total
Petroleum hydrocarbons (diesel range);
Polyaromatic hydrocarbons.
|
The
interior of the Dangerous Goods Store was inspected during the site
visit. The Store has a concrete
floor, which appears largely free from staining or cracking. The contents of the store were found
to be mainly non-hazardous items, although a small number of sealed plastic
containers thought to contain oil were noted. There was no visual or olfactory evidence of any
contamination within the Store or the immediate vicinity.
|
Electricity
Sub-station (on site)
|
Potential Contaminants:
|
Polychlorinated biphenyls (PCBs)
Total Petroleum hydrocarbons
|
It is not possible to ascertain with certainty whether
PCB-containing transformer oils have been used in this CLP secondary
substation. In the absence of
further information, it has been assumed that PCBs are potential contaminants
in this area. Sampling beneath
the sub-station is not possible whilst the sub-station is still in use, as
this would lead to unacceptable safety risks. Sampling and analysis will be carried out following
decommissioning of the sub-station.
|
|
Areas
impacted by aerial deposition from stack emissions
|
Potential Contaminants:
|
Polyaromatic hydrocarbons;
Dioxins;
Metals
(“Dutch List”: Cr, Co, Ni, Cu, Zn, As, Mo, Cd, Sn, Ba, Hg, Pb)
|
It is considered unlikely that stack emissions would give rise to
significantly elevated concentrations of soil contaminants under normal
conditions. However, the
possibility cannot be discounted and hence sampling and analysis was carried
out. Aerial deposition of contaminants arising from stack emissions would be
greatest in the downwind direction from the stack. The prevailing wind direction is from east to west,
meaning that aerial emissions from the stack would be predominantly carried
to the west. Sampling effort was
therefore concentrated to the west of the stack, although confirmatory
sampling was also carried out to the north, south and east of the stack.
|
Cremators
|
Potential Contaminants:
|
Polyaromatic hydrocarbons;
Dioxins;
Metals
(“Dutch List”: Cr, Co, Ni, Cu, Zn, As, Mo, Cd, Sn, Ba, Hg, Pb)
|
The cremators are situated within the building and above a
concrete floor slab. Since the
potential contaminants are predominantly in the solid phase (e.g. particulate
matter) it is considered very unlikely that they could migrate through the
slab into the underlying soil and sampling and analysis beneath the slab was
therefore not considered necessary.
Particulate contamination may however be present within the cremators
and flues.
|
Former Crematorium
|
Potential Contaminants:
|
Total Petroleum hydrocarbons;
Polyaromatic hydrocarbons;
Dioxins;
Metals (“Dutch List”: Cr, Co, Ni,
Cu, Zn, As, Mo, Cd, Sn, Ba, Hg, Pb)
|
No information is available on the layout or operation of the
former crematorium. The site has
undergone considerable disturbance due to site formation for the current
facility. It is not therefore
possible to identify specific features of the former crematorium where
sampling and analysis is required.
The former crematorium lies at depth within part of the Project site
that will undergo minimal disturbance as part of the construction works, and
therefore sampling was not considered necessary.
|
6.8.1
Exploratory holes were sited to
investigate the potential sources of contamination identified above.
6.8.2
Intrusive investigations were not
carried out beneath the floor slab of the Existing Crematorium building, since
it was considered that there is a negligible likelihood that any particulate
contamination within the crematorium building could have migrated through the
concrete floor slab into the underlying soil.
6.8.3
The locations of exploratory holes are
shown in Figure 6.2. The sampling
depths and analytical requirements are shown in Table 6.1 below.
Table 6.1 Exploratory Holes
Location
|
Exploratory
Hole (depth)
|
Sampling
Depths (mbgl)
|
Analytical
Requirements
|
Fuel storage tank
|
DH1 (7m)
DH2 (7m)
TP1 (3m) (1)
|
4.5m; 5.5m; 7m
4.5m; 5.5m; 7m
0.5m; 1.5m; 3m
|
TPH
PAH
|
Dangerous Goods store
|
TP2 (3m)
|
0.5m; 1.5m; 3m
|
TPH
PAH
|
West of stack
|
S1 (0.1m)
S2 (0.1m)
S3 (0.1m)
|
0.1m
0.1m
0.1m
|
Metals
PAH
Dioxins
|
North of stack
|
S4 (0.1m)
|
0.1m
|
South of stack
|
S5 (0.1m)
|
0.1m
|
East of stack
|
S6 (0.1m)
|
0.1m
|
Note: (1) Trial pit
TP1 was terminated at 0.9m due to the presence of large boulders preventing
further excavation. Samples were
taken from 0.5m and 0.9m depth below ground level. No evidence of fuel pipelines or fuel contamination was
noted in this area. It is
therefore considered that the samples taken from this trial pit are adequate to
determine whether contamination is present in this area.
6.8.4
Due to operation constraints as
described in Section 7.5, the CAP
recommended additional site investigations in areas of the site that are
currently in use and cannot be readily accessed. These investigations will be carried out once the existing
facility has been decommissioned.
The additional site investigations are required in the vicinity of the
existing CLP secondary substation during Phase I of the construction and
demolition works, and around the cremators and flues inside the crematorium
building during Phase II of the construction and demolition works. Once access to these areas is
available, a sampling and analysis plan will be prepared for approval by EPD,
additional investigations will take place, and the need for remedial works will
be determined. Any remedial works
required will be in addition to those described in this current report.
6.8.5
The Existing Crematorium will continue
operation until 2006, and there is the possibility that further contamination
could occur between the time of the current investigations (2003) and 2006,
particularly as a result of continuing aerial deposition. It is therefore proposed that, once the
Existing Crematorium has ceased operating during Phase II, confirmatory surface
samples will be taken from the samples points S1 to S6 at a depth of 0.1m, and
these samples will be analysed for the same suite of determinands (i.e.
dioxins, metals and PAH) in order to confirm that no further contamination has
occurred. The Remediation Action
Plan will be revised on the basis of these results.
6.8.6
The underground fuel storage tank and
associated pipework will be removed as part of the site formation works. The base of the excavations will be
inspected during and after tank removal by a suitably experienced environmental
specialist in order to determine whether there is any visual or olfactory
evidence of fuel contamination. If
such contamination is suspected, then confirmatory soil sampling will be
carried out, and the samples analysed for TPH.
6.9.1
Total petroleum hydrocarbons,
polyaromatic hydrocarbons, metals and dioxins in the soil samples tested fell
within the relevant assessment criteria except the following samples:
·
S3:
lead (180 mg/kg); tin (190 mg/kg)
·
S5:
tin (160 mg/kg)
6.9.2
Details of the assessment criteria and
results are documented in Appendix C2 and summarised in Table 6.2.
Table 6.2 Summary of Soil Testing Results
Parameter
|
Units
|
Assessment
Criteria
|
Range
|
Dioxin
|
ng/g, TEQ
|
1
|
0.00378 - 0.00894
|
Silver
|
mg/kg
|
NA
|
<1
|
Arsenic
|
mg/kg
|
30
|
1.4 - 5.9
|
Barium
|
mg/kg
|
400
|
5.7 - 50
|
Beryllium
|
mg/kg
|
NA
|
<1
|
Cadmium
|
mg/kg
|
5
|
<0.05 - 0.09
|
Cobalt
|
mg/kg
|
50
|
0.8 - 3
|
Chromium
|
mg/kg
|
250
|
0.5 - 11
|
Copper
|
mg/kg
|
100
|
0.5 - 29
|
Mercury
|
mg/kg
|
2
|
<0.05 - 0.5
|
Molybdenum
|
mg/kg
|
40
|
<1 - 3
|
Nickel
|
mg/kg
|
100
|
0.8 - 5
|
Lead
|
mg/kg
|
150
|
14 - 180
|
Antimony
|
mg/kg
|
NA
|
<1
|
Selenium
|
mg/kg
|
NA
|
<1 - 4
|
Tin
|
mg/kg
|
50
|
<1 - 190
|
Thallium
|
mg/kg
|
NA
|
<1
|
Vanadium
|
mg/kg
|
NA
|
1 - 15
|
Zinc
|
mg/kg
|
500
|
15 - 77
|
C6-C9 TPH
|
mg/kg
|
1000
|
<2
|
C10-C28 TPH
|
mg/kg
|
1000
|
<25
|
C28-C36 TPH
|
mg/kg
|
1000
|
<25
|
Total PAH
|
mg/kg
|
20
|
<DL - 0.3042
|
6.9.3
Toxicity Characteristic Leaching
Procedure (TCLP) tests were carried out on samples S3 and S5, to determine the
solubility and mobility of lead and tin in these samples and hence determine
the suitability for landfill disposal.
The TCLP test results are shown in Table 6.3.
Table 6.3 Results of TCLP Tests for Parameters
Exceeding Assessment Criteria
|
Lead (ppm)
|
Tin (ppm)
|
Landfill Disposal Criteria
|
50
|
250
|
S3
|
0.03
|
0.015
|
S5
|
<0.01
|
<0.01
|
6.10.1
TCLP testing has been undertaken, and
the concentrations of lead and tin in the TCLP tests were several orders of
magnitude lower than the Landfill Disposal Criteria. Hence pre-treatment of the soil prior to landfill disposal
is not deemed necessary.
6.10.2
The remedial works will consist of
removing soil from an area of 5m radius around the sampling locations S3 and
S5, to a depth of 0.5m. The
removed soil will then be disposed of at landfill. Following excavation, confirmatory testing will be
undertaken to confirm that all contaminated soil has been removed, and a
Remediation Report will be submitted to EPD, detailing the remedial work
undertaken.
6.10.3
The estimated volume of soil that
needs removal is small (less than 100m3), and therefore it is
considered that landfill disposal is the most appropriate remedial measure.
6.10.4
Summary of the remediation works is
shown in the flowchart in Figure 6.3.
Details of the remediation plan (RAP) are provided in Appendix C2. This includes measures to prevent any
adverse water quality impacts during remediation by minimising the possibility
of contaminated run-off being generated.
6.10.5
During removal of the underground fuel
storage tank, appropriate precautions should be taken to avoid
contamination. All fuel tanks and
associated pipework should be emptied prior to any demolition work being
undertaken. Any remaining sludge
or sediment in the tanks or pipework should be removed and disposed of as
chemical waste in accordance with the appropriate regulations for disposal of
such material.
6.10.6
Should contamination be encountered
beneath the fuel tank or the CLP sub-station, further remedial work will be
required. Such potential
contamination would consist of either TPH (in the case of the fuel tank) or
PCBs (in the case of the CLP secondary substation).
6.10.7
Although there is no evidence to date
of contamination associated with the fuel tank, and the drillholes around the
fuel tank do not indicate contamination, there is the possibility that the
material directly underlying the fuel tank may be contaminated with petroleum
hydrocarbons. A realistic worst
case estimate is that the volume of contaminated material would be no more than
100m3 (i.e. approximately 7m x 5m x 3m depth). For this volume of material, treatment
by bioremediation is likely to be uneconomic, and the recommended remedial
strategy would be landfill disposal.
The actual remedial strategy to be adopted is subject to the findings of
the supplementary investigations.
6.10.8
The likelihood of significant
widespread PCB contamination beneath the CLP secondary substation is considered
to be low, due to the low mobility of PCBs in the environment and the low
likelihood of a spillage occurring.
As a realistic worst-case estimate, it could be assumed that less than
25m3 (i.e. 5m x 5m x 1m depth) of material could be contaminated,
and may require stabilisation with cement prior to disposal to landfill. The
actual remedial strategy to be adopted is subject to the findings of the
supplementary investigations.
6.11.1
The proposed development is a
replacement for the Existing Crematorium.
There is the potential for the development to give rise to land
contamination in the future, if appropriate environmental standards are not
followed.
6.11.2
The most potentially significant
future sources of contamination are:
·
Spills or leakage of fuel stored for
the cremators; and
·
Aerial deposition of metals and
dioxins.
6.11.3
Provided the New Crematorium complies
with the prescribed air emissions limits, it is considered very unlikely that
aerial deposition would give rise to significant land contamination, due to the
very small quantities of metals and dioxins that would be emitted.
6.11.4
The fuel storage facilities to be provided
in the New Crematorium should be constructed, maintained and inspected in
accordance with the provisions of the Dangerous Goods (General) Regulations
(Cap. 295B) and the guidelines presented in “Guidance for the Design,
Construction, Modification and Maintenance of Petrol Filling Stations”
(Institute of Petroleum, 1999), and with the necessary approvals from the Fire
Services Department. To mitigate
the environmental impacts from operational land contamination, the following
mitigation measures shall be implemented for installation and operation of any
underground fuel tanks:
·
The
underground fuel tank(s) shall be of a specified durability and placed within a
concrete pit to avoid direct contact of the tank surface with soil.
·
The
concrete pit shall be accessible to allow tank integrity test to be carried out
on an annual basis, or when deemed necessary by an independent qualified
surveyor or structural engineer. Any potential problems such as potential
cracking shall be rectified as far as practicable.
·
Diesel
fuel pipelines shall preferably be installed above ground. If underground
piping is unavoidable, concrete lined trenches shall be constructed to contain
the pipelines. The distance between the cremators and the underground tanks
shall be minimized as appropriate to avoid the need for long pipelines.
·
Proper
installation and use of meters (e.g. at the two ends of any pipeline) would
allow any unexpected pressure drop or difference and signs of leakage be
detected from routine inspection or during diesel fuel pumping. Any identified
leakage shall be reported to the plant manager in-charge.
·
Any
spillage of fuel shall be removed immediately by portable pump when the
quantity is large or by absorbing materials when the quantity is low or with
similar effective tools as appropriate. Used absorbing material shall be
properly stored and disposed of as chemical waste.
·
The
underground tanks refueling (from tank trucks) shall only be undertaken by
authorized staff of the fuel company using the company's standard procedures to
avoid spillage of diesel fuel.
6.11.5
Provided the above measures are
implemented properly, the likelihood of uncontrolled leakage of fuel giving
rise to land contamination is low.
If in the future such facilities are decommissioned, contamination
testing will be required in order to identify and delineate any contamination
that may have occurred. No
additional land contamination impacts are envisaged during the transitional
stage of the project.