11.1
This section reviews the potential
environmental issues associated with land contamination and assesses its
implications for the proposed land uses at the site in accordance with the EIA
Study Brief Clause 3.4.5.1.
11.2
Two publications issued by the
Environmental Protection Department (EPD), ProPECC
PN 3/94 - Contaminated Land
Assessment and Remediation and Guidance
Notes for Investigation and Remediation of Contaminated Sites of: Petrol
Filling Stations, Boatyards, and Car Repair / Dismantling Workshops,
provide guidance on land contamination assessment. In ProPECC PN 3/94, it
makes reference to the criteria developed in the Netherlands (known as “Dutch
List”). Although there is currently no
standard for the clean-up of contaminated soil and groundwater in Hong Kong,
the Dutch B level of the Dutch List is normally used as the clean-up target for
soil in Hong Kong. Where groundwater
concentrations exceed the Dutch B level, a risk-based assessment is usually
required to establish the nature and extent of remediation required.
11.3
Provisions for consideration of land
contamination issues are given in the Section 3 “Potential Contaminated Land
Issues” of Annex 19 “Guidelines for Assessment of Impact on Sites of Cultural
Heritage and Other Impacts” of the Technical Memorandum on Environmental Impact
Assessment Process (EIAO-TM).
11.4
The legislation and guidelines
relevant to the issue of land contamination, due to the handling, disposal and
treatment of contaminated waste in Hong Kong are listed as follows:
·
Waste Pollution Control Ordinance
(WPCO)
·
Waste Disposal Ordinance (Cap. 354)
·
Waste Disposal (Chemical Waste)
(General Regulation (Cap 354), and
·
Code of Practice of the Packaging,
Labelling and Storage of Chemical Waste, EPD (1992)
11.5
The objective of the land
contamination assessment is to identify and evaluate the potential of ground
contamination within the Study Area. In
order to accomplish the objective, the following tasks have been undertaken:
i)
A desktop study to review the current
and historical land uses along the alignment of proposed elevated roads. The study aims to provide a clear and
detailed account of the relevant past land history and the present land uses
along the alignment, which identifies the contaminated areas with a potential
to cause contamination.
ii)
Identification of works associated
with the construction of elevated roads that may have impact on the
contaminated sites caused by handling, collection and disposal of the
contaminated materials.
iii)
A review of environmental information
in relation to potential contamination have been requested from the Fire
Services Department (FSD), Local Control Office (LCO) of the Environmental
Protection Department (EPD) and Lands Department (LandsD).
iv)
Site reconnaissances to confirm the
existing land uses.
11.6
In addition, the following sources of
information have been collated and reviewed:
i)
Contemporary and historic Hong Kong
Government Survey maps
ii)
Aerial photographs
iii)
Hong Kong Geological Survey Solid and
Superficial Geology Series Maps
iv)
Historic records of chemical storage /
spillage within the Study Area
11.7
The Study Area of the land
contamination assessment includes the area along the alignment of the proposed
elevated roads and existing roads proposed to be widened/modified.
11.8
Preliminary information reveals that
there are several sites with potential contaminative land uses within the Study
Area, the location of these areas is shown in Figure 11.1 and their existing
land uses are described below:
· Site A: an area used as vehicle parking area, open storage area with
several vehicle repairing / servicing workshops
· Site B: Highways Department – Lok Ma Chau Maintenance Yard
·
Site
C: an area adjacent to an open storage area, which construction works under
Drainage Services Department’s Eastern Main Drainage Channel (EMDC) is being
conducted
·
Site
D: a site vehicle parking area
·
Site
E: an area used as car parks, open storage area and vehicle repairing /
servicing workshops
11.9
The review of the Hong Kong and
Kowloon Geological Survey Map Sheet 2 indicates that the superficial deposits
at Study Area consist of alluvium predominately.
Site
History
11.10 The site history information of the Study Area was obtained by
reviewing relevant historical aerial photographs. Table 11.1 summarizes the aerial photographs which have been
reviewed.
Table 11.1 Historical
Aerial Photographs Reviewed
Year
|
Height (feet)
|
Photograph Reference No.
|
1987
|
4,000
|
A09732
|
1989
|
4,000
|
A18205
|
1990
|
1,900
|
A22669
|
1993
|
4,000
|
A36429
|
1995
|
3,500
|
CN11878
|
1997
|
3,000
|
CN16700
|
1999
|
1,000
|
CN23515
|
2001
|
2,700
|
CW31404
|
2003
|
3,500
|
CW46729
|
11.11 The changes of land uses at the Study Area are described below:
·
In 1987, the Study Area was occupied
by fish ponds and farmland
·
In 1989, San Tin Highway was being
constructed in the Study Area
·
In 1990, the construction of San Tin
Highway had been completed. There were
no significant human activities / construction took place at the area
immediately adjacent to the Highway (including Sites A to E)
·
Site A was an area mainly used for
container storage and long vehicle parking.
Moreover, the area seemed to be unpaved as observed in the photo
·
There was construction activity at
Site B
·
Site C was used as a container yard
and long vehicle parking area.
Moreover, a number of workshops were located in the area. The area seemed to be unpaved as observed in
the photo
·
Site D was an unpaved road
·
Site E was used as an area for vehicle
parking, open storage yard and workshops.
The area seemed to be unpaved as observed in the photo
·
In 1995, some site offices had been
built at Site B and some areas at Site B were used for vehicle parking. However, there was no significant change of
land use observed at other sites
·
In 1999, site D was used as a site
office. However, there was no
significant change of land use observed at other sites compared to 1995
·
In 2001, part of Site A area had been
used for private car parking, while Site D was used as a vehicle parking
area. However, there was no significant
change of land use observed at Site B, Site C and Site E
·
In 2003, Site C was no longer an area
used for long vehicle parking area and container storage yard. Site C was observed to be a bare ground from
the photo
11.12
According to the information provided
by FSD, there is no record regarding storage or leakage of dangerous goods
within the Study Area for the past 20 years.
11.13 Information of existing land uses in the Study area was obtained
from Lands Department and site reconnaissances conducted on 1 April 2003 and 18
September 2003.
11.14 Based on the site reconnaissance conducted on 1 April 2003, it is
confirmed that there are private car parking area and several vehicle servicing
/ repairing workshops located at Site A.
A site office of Highways Department is located at Site B.
11.15 Another site reconnaissance was conducted on 18 September 2003. It was observed that construction works were
being conducted at Site C. By
observation, the excavated soil seemed not to be heavily contaminated. However, some localised red stains were
observed in the soil. Moreover, it was
confirmed that Site D is paved and is no longer used as site office. There were a few site vehicles parked in the
area. For Site E, since site entry was
not allowed, observation could only be made at the entrance of the site. It was observed that the site consisted of a
large area for open storage, car-parking area and several vehicle servicing /
repairing workshops. Moreover, ten to fifteen vehicles were observed parked at
the entrance of Site E, which the ground was paved. However, detailed operations of the workshops could not be
observed.
11.16 Construction workers are more likely to be exposed to any potential
contaminated material than the future users of the land within the Study
Area. It is because the construction
workers could be exposed to potential contaminants during excavation and
preparation of foundation works.
Depending on the nature of the contaminants, hazards during preparation
of foundations and subsurface services could be significant. The principal exposure routes for workers
include:
·
ingestion of contaminated soil through
eating, drinking or smoking on site;
·
dermal contact with contaminated
spoil; and
·
inhalation of contaminants if they are
volatile.
Identification
of Potential Source of Impact
Site A
11.17 According to the site history information, Site A has been used as
container storage and long vehicle parking area since 1993. In the site reconnaissance, it was observed
that private car parking area and vehicle repairing / servicing workshops were
located at the site. The information
gathered from interviews with personnel on site indicates that the vehicle
repairing / servicing workshops at Site A have been in business before year
1996. Observation and communication
with relevant personnel indicated although no large amount of chemicals and
petroleum oils were stored within the area, paints, hydraulic oil, lube oil,
solvents and acid batteries were used in the workshops. Moreover, localized, small-scale oil stains
on bare ground were observed. It is
considered that land contamination at the site is likely.
11.18 The main expected contaminants from container storage area, long
vehicle parking area, vehicle repairing / servicing workshops are fuels,
paints, solvents, petroleum oils, and possibly acids. The potential contaminants associated with the above land uses
are listed in Table 11.2.
Table 11.2Potential Contaminants associated with historic
and present land uses at Site A
Site B
11.19 According to site history information, Site B has been used as a
site office of Highways Department since 1995.
During the site reconnaissance, it was observed that there were a
vehicle parking area and several site offices at Site B. Based on observation on site and information
gathered from site office personnel, no chemicals were stored and no vehicle
repairing works was undertaken on site.
According to site office personnel, any waste generated on site was
handled and disposed properly.
Therefore, it is considered that land contamination at Site B is unlikely.
Site C
11.20
According to the site history
information, Site C has been used as an area for container storage, long
vehicle parking and vehicle repairing / servicing workshops since 1993. According to information gathered from
aerial photo review and site reconnaissance, the site was no longer used as
open storage and long vehicle parking area in 2003. Moreover, construction works under Drainage Services Department’s
San Tin Eastern Main Drainage Channel (EMDC) Project were being conducted on
site during site reconnaissance.
11.21
It should be noted that prior to the
commencement of construction works, contamination investigation works at Site C
had been carried out and the contaminated soil had been treated/disposed of as
suggested in the endorsed Remediation Action Plan (RAP). Therefore, there should be no further land
contamination concern present at Site C.
Site D
11.22 Based on the site history information obtained from aerial
photographs, Site D was an unpaved road in 1993 and the site became a site
office in 1997. In 2001, no site office
was located in the area and remained as an area for vehicle parking.
11.23 During the site reconnaissance, it was observed that a few site
vehicles were parked in this paved area.
No workshop, vehicle cleaning area or oil stain was observed at
site. Based on the information
obtained, it is considered that land contamination at Site D is unlikely.
Site E
11.24 According to information gathered from aerial photographs review,
Site E has been used as an area for long vehicle parking, open storage and
vehicle repairing / servicing workshops since 1993. As observed from the aerial photos, Site E was not paved in
1999. Entry of the site was not allowed
during the site reconnaissance.
Therefore, observation can only be made at the entrance of the site and
it was observed that the site is paved.
Moreover, a vehicle parking area, open storage area and several vehicle
repairing / servicing workshops were observed within the site.
11.25
It is considered there is a
possibility that the soil at Site E is contaminated because aerial photographs
indicated that the site was unpaved and it is used as open storage area and
vehicle parking area. The main expected
contaminants from vehicle parking area are fuels, petroleum oils and possibly
acids. The potential contaminants
associated with the above land use are listed in Table 11.3.
Table 11.3Potential Contaminants Associated with Historic
and Present Land Uses at Site E
Land Uses
|
Potential
Contaminants
|
Container Storage
Area / Long Vehicle Parking Area
|
BTEX, petroleum
hydrocarbons, acids (from acid batteries)
|
Vehicle Repairing /
Servicing Workshops
|
benzene, toluene,
ethylbenzene, xylene (BTEX), petroleum hydrocarbons, solvents, paints, acids
(from acid batteries)
|
11.26 To conclude, there is a potential concern of land contamination at
Site A and Site E while it is considered that land contamination at Sites B, C
and D is unlikely.
Identification of
Potential Impact
11.27 In accordance to the above sections, Site A and Site E are
considered to be areas having potential land contamination. The relevant land uses in the area include:
·
container storage area;
·
long vehicle parking area; and
·
vehicle repairing / servicing
workshops.
11.28 The potential contaminants identified are: benzene, ethylbenzene,
toluene and xylene (BETX), petroleum hydrocarbons, fuels, solvents, paints and
acids. The implications of potential
land contamination are listed as follows:
i)
There could be potential adverse
effects on the health and safety of workers on site during construction. Site workers maybe exposed to contaminated
materials by means of incidental ingestion of contaminants, dermal contact with
contaminated soil and groundwater during excavation, and inhalation of volatile
contaminants in soil.
ii) Disposal of potentially contaminated soil arise from site clearance,
excavation, construction works, which prior agreement from EPD should be
sought.
11.29 The primary potential source of land contamination impact for the
Project is the potential contaminants arisen from the past and present land
uses at Site A and Site E. As sections
of proposed elevated roads and roads proposed to be widened/modified will pass
through the site area, land contamination impact would arise from excavation
works. Visual observation in site
reconnaissances indicated that oil stains and contamination are not widespread
in the site areas. However, the
vertical extent of any contamination in subsurface could not be evaluated. The migration (if any) of contaminants is
considered to be limited because of the presence of alluvial material in the site
area.
11.30 Although detailed information concerning construction method is not
available at this investigation stage, it would be considered that only limited
amount of soil material would be excavated and disposed of. Therefore, it is considered that the impacts
related to health effects on construction workers and disposal of contaminated
material would be surmountable.
11.31 As it is considered that land contamination impact is likely at Site
A and Site E, a land contamination assessment should be conducted at these site
areas prior to the commencement of site clearance/excavation works. Figure 11.2 showed the proposed potential
zones for conducting site contamination investigation. The land contamination assessment would
include sampling and analysis of soil / groundwater to confirm the presence and
level of contamination (if any) in the area.
The information obtained from the assessment would be used to determine
the appropriate handling and disposal requirements of the excavated materials.
11.32 The sampling and analysis of soil and groundwater should be
conducted in accordance with EPD’s requirements. A Contamination Assessment Plan (CAP) should be submitted to EPD
for endorsement prior to conducting the contamination assessment works at Sites
A and E under the design and construction stage of the Project. Based upon an endorsed CAP, a contamination
assessment should be conducted and a Contamination Assessment Report (CAR)
should then be compiled for EPD’s approval.
If contamination is identified during the preparation of CAR, a
Remediation Action Plan (RAP) should be submitted to EPD for approval and site
clean up works should be conducted before construction works of the Project.
11.33 The following environmental and safety precautionary measures should
be implemented and reviewed during the construction of elevated roads, in order
to minimize the potential health impact on the site workers:
·
Site workers should wear appropriate
personal protective equipment (i.e. gloves, mask) when exposed to potential
contaminated soil and groundwater;
·
Eating, drinking and smoking should be
prohibited in contaminated areas to avoid advertent ingestion of contaminants;
·
Stockpiling of contaminated soil
should be avoided as far as possible.
If this cannot be avoided, the stockpile of contaminated material should
be segregated from the uncontaminated ones.
Moreover, the contaminated materials should be properly covered with
appropriate material (e.g. tarpaulin) to avoid leaching of contaminants,
especially during heavy rainstorm;
·
Bulk earth moving equipment should be
utilized as much as possible to minimize handling and contact of contaminated
materials of the workers;
·
Adequate washing facilities should be
provided on site;
·
If disposal of contaminated soil and
groundwater is needed, the Contractor should dispose of the contaminated soil
according to the requirements agreed by EPD
11.34 With the implementation of
the recommended mitigation measures for the assessment of the presence and
extent of contamination, handling and disposal of the identified (if any)
contaminants, no residual impact was anticipated during the construction works
for the proposed elevated roads and road widening/modification works.
Environmental Monitoring and
Audit (EM&A) Requirements
11.35 Two potential zones have been proposed for further investigation due
to presence of potential contaminative land uses located within the Project
boundary. A CAP should be submitted to
EPD for endorsement prior to conducting the contamination assessment
works. Contamination assessment at the
potential contaminated zones should follow the requirements laid out in the
CAP. A CAR and RAP, where necessary,
should be prepared based on the results obtained from the site investigation
and submitted for EPD’s approval. Details of the requirements are provided in a
stand-alone EM&A Manual.