3.1.
A
sizeable works area is required for the treatment of contaminated material
based on the outcome of the site investigation and land contamination
assessment. The purpose of this chapter
is to present the findings of a site search and comparative evaluation of works
area options together with a recommendation of the preferred site.
3.2.
The
tight construction programme for the decommissioning of the former Cheoy Lee
Shipyard and subsequent theme park development including the Water Recreation
Centre dictates that nearly half of the contaminated material generated from
the shipyard be treated elsewhere.
This is limited to contaminated material requiring either thermal
desorption or biopile treatment.
In each case the material will also undergo solidification as a second
stage of treatment. The remainder
of contaminated material will require solidification only and will be treated
on site. The size of these works areas for decontamination
depend to a large degree on the nature and extent of the contaminated soil, the
storage and treatment method, the
capacity of relevant treatment plant and other factors such as access
arrangement and overall site shape.
The location of the works areas for decontamination depends on the
required size of the works area, the duration of the treatment period and land
availability, the environmental impact arising from the transportation of the
soil and the environmental impact arising on any sensitive receivers in the
vicinity of the site. The volume
of the temporary storage of material is expected to include most of the
contaminated material generated because the rate of material excavation from
the site over a period of roughly 6 months will significantly exceed the
treatment rates with treatment periods lasting between 1 to 3 years.
Broad
Criteria for Decontamination Works Area
3.3.
The
broad criteria for the decontamination works area include;
(i) Environmental acceptability
of any impacts including those on sensitive receivers in the vicinity of the
site to be affected by the decontamination work.
(ii) Proximity to the site at Penny’s
Bay, ege.g. North Lantau to reduce risks of
transportation and wider environmental impact.
(iii) Accessible by road or by
sea. For sea transport the works
area would require a 60m long vertical seawall with a minimum depth of water of
4.5m.
(iv) Period of availability:
Processes Area
(ha) Duration Period1
On Site
Solidification
only 0.4 0.6
years Nov
02 to May 03
Storage 0.9 0.6075
years NovSept 02 to May
03
Material
Handling 0.8 0.6075
years NovSept 02 to May
03
&
Circulation
Total On Site Requirement 2.1ha
Off Site
Biopile 0.4 2
years NovOct 02 to NovOct 04
Thermal
Desorption 0.4 2
years Feb 04Sept 03
to Feb 06Sept 05
Solidification 0.4 2
years Mar 04Oct 03
to Mar 06Oct 05
Storage 1.2 3.75 years JulSept 02 to Mar 06Sept 05
Material
Handling & 2.1 3.75 years JulSept 02 to MarSep06t 05
Circulation
Total Off Site Requirement: 4.5 ha
Note 1 : The
periods given in above table are the best estimates based on the present
assessment, refer Programme in Figure 4.1517. Actual periods of site occupation may vary according to
risks associated with treatment plant procurement and shipping, commissioning
and approvals and treatment rates and weather conditions. The above periods do not include
establishment or decommissioning.
3.4.
It is
preferable to treat the contaminated material as close to the shipyard site as
possible to minimise the impact of material movements and risk of impacts on
other areas. Sites with non public road access or marine access are preferred
for bulk material transportation to avoid the need for voluminous contaminated
material movements on public roads.
3.5.
The
site search has investigated and compared available areas within the Penny’s
Bay Reclamation area and other areas at North Lantau, refer Figure 3.1
Potential
Sites for Decontamination Works
Decontamination
Works Areas within the Penny’s Bay Development Area
3.6.
Potential
decontamination works areas of the Penny’s Bay Development site are very
limited. The availability of the site area is dictated by the schedule of handover
dates from Penny’s Bay Reclamation (Contract CV/99/12) from October 2001 to
January 2003, the tight programme of infrastructure works which has been
programmed without float, and the timetable for the hand back of areas to key
parties such as HKITP, MTRCL and ASD and other Government Departments. In
addition, most of the areas within Penny’s Bay will be handed over to HKITP for
construction of the theme park, hotels and associated supporting facilities
right after completion of the reclamation works. Areas not handed over early to other parties will be
occupied by the Infrastructure Works which are currently targeted for
completion in mid 2005. Thus,
these infrastructure works areas are not available for decontamination works.
After this time the opening of the Theme Park makes any temporary
decontamination works within such areas unacceptable.
3.7.
The
only areas not constrained by the construction of the permanent infrastructure
works are the areas to the East of the RD&E area (Area 6B). Immediately following the completion of
this area of reclamation under Penny’s Bay Reclamation (Contract CV/99/12) the
contractor for infrastructure works Contract 1 (Contract No. CV/2000/09) will
receive Area 6B by January 2003 for construction of temporary access roads,
stockpiles of fill material and works areas until early 2005. A small area (Area 2L) of 0.8ha
immediately adjacent to the south east corner of Area 6B, will be handed over
to Contract 2 to
use for a barging point.
3.8.
The
completion of thermal desorption treatment is anticipated in early 2006late 2005,
refer Figure 4.157. The
programme however is subject to various risks including those associated with
the time required for treatment plant procurement, shipping, commissioning and
approvals and treatment rates and weather conditions. The use of a site at Penny’s Bay for thermal desorption
therefore runs a high risk that the plant will still be operating when the
Theme Park is due to open. Given
the high number of visitors anticipated at the Theme Park the simultaneous
operation of the thermal desorption treatment plant would not be
environmentally acceptable or aesthetically desirable. In such case then the thermal
desorption plant would need to be relocated to another site if available with
the disadvantage of associated additional costs and wider risks and impacts In such case
then the thermal desorption plant would need to be relocated to another site if
available with associated costs and impacts.
3.9.
In order to accommodate the intended
decontamination plant and stockpiling area, a site of around 5 ha will be
requiredIn order to accommodate the intended
decontamination plant and stockpiling area, a much bigger site with a size of 5
ha will be required. Early surrender of this sizeable area would
inevitably have detrimental effects on the progress of Contract 1 (Contract No.
CV/2000/09) and would require
negotiation with the Contractor for Contract 1 on financial and cost
implications. Of particular
concern in such negotiations would be the long lead time required for the
negotiation process and the programme impact to Contract 1 and its knock on
effects on Theme Park opening. The
other concern is the uncertainty on the outcome of such negotiations, which could undermine
the planning and tendering of Contract 2, and jeopardise timely opening of the
Theme Park. In view of the
uncertainties associated with this site and the potential impact to the
Project, this site will not be considered further.
3.10.
A
smaller works area within the former Cheoy Lee Shipyard could be used for the
temporary storage and treatment of material requiring solidification only. This represents 55% of all material to
be excavated for treatment. The
area available is around 2 ha in size located in Area 2 which will ultimately
become the Tree Farm within the Water Recreation Centre. The site is required in the first stage
of Contract 2 to establish the solidification plant in order to minimize
temporary storage requirements of excavated material. The existing formation level is around +5.0mPD and the site
would be available for setting up the solidification plant immediately
following excavation and backfilling works in this area. Subsequent filling, formation, landscaping
and other works in this area would need to await the completion of
solidification treatment and decommissioning in July 2003.
3.11.
A
further area for biopiling cannot be accommodated within the former Cheoy Lee
Shipyard because of the impact on the programme of Contract 2 works. The commencement of biopiling treatment
at the former Cheoy Lee Shipyard would need to await completion of a portion of
excavation, backfilling and formation in Area 3 by around January 2003 i.e.
around 5 months later than the biopiling is proposed to commence off site. On this basis the completion and
decommissioning of on-site biopiling would not be expected until the end of
February 2005, after which there would not be insufficient time for
the construction of the permanent works under Contract 2 in the affected area.
Decontamination Works
Areas Outside the Penny’s Bay Development Area
3.12.
A
search for potential decontamination works areas on Lantau and Tsing Yi was
carried out with the assistance of DLO/Islands and DLO/Kwai Tsing. Three potential areas at North Lantau
were identified for further investigation by DLO/Islands concerning land
status. These areas include To Kau
Wan, Tai Chuen and Suiu Ho Wan. The land status of these areas is discussed below. DLO/Kwai Tsing has advised that no
suitable sites for decontamination works are available in Kwai Tsing.[1]
To Kau Wan
3.13.
An
area of Government land at To Kau Wan was identified in April 2001 as a potential
site for decontamination works, refer Figure 3.2. The area of the site is 6.08 hectares
which will be sufficient for the proposed works. This area of reclamation is formed to a relatively uniform
level varying between +5.1 mPD and +6.2 mPD. The site has an existing pier and
more importantly a vertical seawall of over 200m length which will facilitate
the establishment of the treatment plant on site and possibly the loading of
treated materials for disposal off site.
The vertical seawall has a minimum water depth alongside of 5m
which5m,
which will cater for the drafts of barges envisaged. The only existing road access to the site is via a
restricted road under the control of TMCA currently accessible only from the
Tsing Ma Toll Plaza of NLH. A
temporary access road to this area is to be constructed under MTRCL’s PBRL tunnellingtunneling
contract and CED’s Infrastructure Contract 1. This site access road will avoid the need to use NLH for
bulk movements of contaminated material.
The alignment of the temporary access road to To Kau Wan is shown on Figure 6.3. The site is wholly outside the MTRC railway protection
boundary.
3.14.
The
area is not currently assigned for any use and has therefore been reserved for
use by this project. CED are
however in discussion with HyD concerning the possible shared use of this site
by HyD for loading/unloading of construction materials for Route 10 (Tsing Lung
Bridge) project. This EIA
considers the adjacent temporary uses associated with Route 10 construction project.
3.15.
A part
of the site (0.75ha) has been used by Infrastructure Works Contract 1 for trial
berm works for this project (TGLA No. TIS 419 Land for Soil Compaction Trial at
To Kau Wan North Lantau, CED expiring February 2002). This work however has now been completed and is available
for use for the proposed decontamination works.
3.16.
The
possible works area at To Kau Wan is adjacent to an existing shipyard and the
NLH Lantau Toll Plaza Administration Building both of which would be considered
sensitive receivers. To Kau Wan is
also close to the Route 10 (NLYLH) construction works site at North
Lantau. The works are tentatively willscheduled to commence
in mid 2003. In addition,
to the NE along the adjacent coast, several little egrets have been observed
roosting in small patches of secondary woodland. This area could potentially
serve as a nesting area for Ardeids.
3.17.
The To
Kau Wan site is designated “Undetermined” on the North-East Lantau OZP No.
S/I-NEL/8. Temporary uses expected
to be less than five years, as in the case for the proposed decontamination
works, are always permitted as long as they comply with the requirements of
other government departments.
Tai Chuen
3.18.
The site
at Tai Chuen is 1.65 hectares of reclamation adjacent to and north of the south
west abutment of the Kap Shui Mun Bridge, refer Figure 3.1. The site is formed to between +5.4 mPD
and +9.4 mPD and features a 130m long vertical seawall with landing steps. There is no existing road access to the
site. The site is wholly outside
the MTRC railway protection boundary.
3.19.
The
Tai Chuen site is designated “Green Belt” on the North-East Lantau OZP No.
S/I-NEL/8. Temporary uses expected
to be less than five years, as in the case for the proposed decontamination
works, are always permitted as long as they comply with the requirements of
other government departments.
3.20.
As
indicated on the land status plan an area at the south edge of the site (0.2ha)
is occupied by CLP Power Hong Kong Ltd under a Short Term Tenancy due to expire
on 1st June 2002. A
similar size area (0.2 ha) at the west corner of the site is currently used by
Highways Department for the storage of rock cores under TGLA No. TIS 368
Storage Rock Core at Tai Chuen, Lantau Island due to expire on 31st
January 2003.
3.21.
The
Tai Chuen site is 9.6km by sea (via Ma Wan Fairway, North of Ma Wan then via
Kap Shui Mun Fairway) from the temporary works area (Area 2L) at Penny’s Bay.
3.22.
The site
is constrained to by the proximity of the Kap Shui Mun Bridge. In addition a
few existing dwellings have been noted to exist adjacent to the North edge of
the site. These will constrain the location and arrangement of treatment plant
and operations. This site is
considered not favourable on environmental grounds due to the potential visual
and air quality impacts.
Siu
Ho Wan
3.23.
During
the site search exercise, Siu Ho Wan was targeted as a potential area for the decontamination
works. However, the site searching exercise revealed that most areas in Siu Ho
Wan have been allocated permanently for infrastructure works and the remaining
areas have already been reserved for other uses.
3.24.
The
Site search at Siu Ho Wan identified one potential area for decontamination
works however this area is constrained by a current land allocation. The area
which measures 2.4ha is accessible by road and was adjacent to the existing Siu
Ho Wan Water Treatment Works and Siu Ho Wan Police Vehicle Pound. The site is
too small to meet the decontamination works area requirement (4.5ha) and is
reserved under GLA-TIS 10/1/21 Proposed Grease Trap Waste Treatment Facilities
(Fall Back Option). This site is
also adjacent to the Suiu Ho Wan Water Treatment Works raising the
risk of potential contamination of the water supply. Accordingly this site will not be considered further.
3.25. Another nearby area is adjacent to and West of the Siu Ho Wan Sewerage Treatment Works but is allocated to DSD under GLA-IS 424 Sewage Treatment Works Upgrading at Siu Ho Wan and GLA-TIS 406 Temporary Works Area. Both these area allocations were handed over in July 2001 by DSD to the relevant contractors for the construction of the Outlying Islands Sewerage Stage 1 Phase 1 C - Sewage Treatment Works Upgrading, Contracts DC/99/10 and Contract DE/99/12 for construction works until November 2006.
Comparison of Decontamination Works Areas Outside the Penny’s Bay Development Area
3.26.
A
comparison of the available sites for decontamination works areas has been
prepared taking into account of the key factors and constraints of each. The
characteristics of particular importance are the size and availability of the
site over the duration of the decontamination treatment period, the
implications of any delays in the completion of the treatment affecting the
infrastructure development, the distance from the shipyard and means of access,
the suitability of existing facilities for access, the site constraints such as
the presence of any sensitive receivers and the potential environmental effects
from storage and treatment.
Site Area
3.27.
The
area required for storage and treatment of contaminated material is about 5ha. At
To Kau Wan the available site area of 6.1ha will be sufficient to cater for the
proposed decontamination works. The 1.65 ha site at Tai Chuen will not be
adequate for all the decontamination works and would therefore involve the use
of an additional site of at least a further 3.4ha. As the treatment processes
are interrelated, the use of multiple sites is less efficient and requires
double handling of materials causing wider environmental impact. Thus, the use of multiple sites for off
site treatment is not preferred.
It would also involve a larger land take because of the duplication of
treatment and handling areas and a wider extent of risk associated with the
transport of material. On this
basis the site at To Kau Wan is preferred from a site area view point because
this is the only site with confirmed availability of adequate site area for all
the decontamination works.
Availability
3.28.
The availability of the To Kau Wan site is confirmed
with land allocation procedures in an advanced stage for the envisaged time
span of the decontamination works. The site at Tai Chuen is also currently
unallocated and would therefore be available for use over the expected duration
of the decontamination works.
However, Tai Chuen site is too small to accommodate the decontamination works.
Site Access
3.29.
A
temporary road access will be constructed between Road P2 at Yam O along the
south side of the LAR to To Kau Wan for the transportation of contaminated
material to To Kau Wan. This road will
not be open to the public and will not therefore pose any significatntsignificant risks or have
any effect on traffic on public roads.
The To Kau Wan
site also has adequate marine access via an existing vertical seawall and
pier. Marine access may be
used for the establishment of decontamination plant and for the shipment of
treated material off site. The site at Tai Chuen has no means
of road access but has adequate marine access via an existing vertical
seawall. All movements of material
to and from this site would need to be via the sea. Both sites therefore have adequate access provisions.
Transport Distance
3.30.
The
distance to the To Kau Wan works area is 3.6km via the temporary access road
between Yam O and To Kau Wan (refer Figure 6.3)
whereas the transhipment distance to the Tai Chuen works area by sea via Ma Wan
Fairway, North of Ma Wan then via Kap Shiu Mun Fairway would be 9.6km. The movements of contaminated material
to Tai Chuen would also require land transport via the interim access road at
Penny’s Bay over a distance of 3km from CLS to the temporary barging
point. The total distance
travelled by land and sea to Tai Chueno Kau Wan is
12.6km. To Kau Wan is therefore
preferred on the basis of transport distance.
Impacts from Transport
3.31.
The
impact from the transportation of contaminated material by road is considered
to be acceptable given the precautions taken for the various types of
contaminated material. In particular the proposed containerisation of material
contaminated by dioxin will ensure that the impact of any road transport
accident will be small. In addition the use of escort vehicles which will
travel ahead of the trucks carrying dioxin contaminated material will greatly
minimise any risk of accidents on route to To Kau Wan. The route to To Kau Wan is entirely on
site access road other than the short section (390m) of Road P2 at Yam O (currently used only for construction
and franchised buses for construction workers) and the 112 m of restricted road
at To Kau Wan under the control of TMCA.
The Infrastructure Contract 2 contractor will also be required to have
in place a rescue plan and a contingency plan to ensure a rapid clearance and
cleanup in the event of any accidents.
In the same way for marine transport of material to Tai Chuen, the
containerisation of contaminated material, would minimise risks to the
environment during transhipment. In particular the risk of significant marine
incident involving potential cargo losses over the course of the project has
been estimated to be very low. The consequent risk of loss in dioxin
contaminated material and impact to the environment is also very low due to
precautions such as the use of rubber seals on containers doors and a tie down
system for the containers on the vessel. Overall the risks of impacts for
various modes of transportation of dioxin contaminated material are therefore
considered acceptable.
3.32.
For
material with other types of contamination requiring biopiling and subsequent solidification,
bulk transportation by road (truck) to To Kau Wan is proposed in line with HK
practice. The use of a temporary
access road has the benefit of avoiding large number of truck movements on
public roads. The use of a
temporary access road and the very limited section of Road P2 at Yam O
(currently used only for construction and franchised buses for construction
workers) will reduce the risks of incidents and any significant impacts. The material carried by the dump trucks
would be covered with impermeable liners to protect the material from wind and
rain and avoid any losses during transportation. The rescue and contingency plans put in place under
Infrastructure Contract 2 will also ensure a rapid clearance and cleanup in the
event of accident. The risk of
environmental impacts from marine transport to Tai Chuen is considered higher
for marine transport for bulk material because of the higher risk of material
losses in the event of a serious accident, however unlikely. It must be noted
however that based on historic records on marine incidents the risks of
significant marine accidents for vessels transporting material with
contamination other than dioxin in bulk would be expected to be insignificantly
low due to the use of self-propelled barges and restricting such shipments to
daylight hours. The consequence of
road accidents during transportation leading to waste implication between
Penny’s Bay and off-site treatment area is presented in Section 6.
3.33.
The overall
risk of impacts from transportation would increase with the distance travelled
and on this basis transportation impacts associated with the To Kau Wan are
considered less than Tai Chuen.
The transportation risks to these sites are however considered to be
very low and acceptable.
Impacts from Storage
3.34.
The
potential impacts of storage are considered to be acceptable given that the
precautions recommended are appropriate to the types of contamination involved.
The use of an enclosed building for dioxin contaminated material will ensure
that the stored material will be unaffected by environmental effects such as
wind, rain etc. The enclosed building will minimise any potential impacts to
the surrounding air quality particularly during periods of material storage or
extraction.
Environmental Impact
3.35.
The
potential environmental impacts associated with the decontamination works are
considered acceptable and can be mitigated for the To Kwau Wan site as no
sensitive land uses are located nearby. PotentialPotential impacts to Ardeids (which
may use woodland to the Northeast of the site for roosting and possibly
nesting) are expected to be low, as
the sighting of egrets was probably an occasional one and there would be no
direct impact on the egrets (refer to section 8 for details). In addition, To Kau Wan is further away from Ma Wan
Fish Culture Zone than Tai Chuen.
As a result, To Kau Wan is more favourable on environmental grounds.
3.36.
This assessment has considered various potential sites for the
proposed decontamination works. On
site treatment is possible for 48,000m3 of material requiring
solidification only. This
represents 55% of all material requiring treatment and occupies 2ha of the
former Cheoy Lee Shipyard.
Treatment of the remaining contaminated material such as that requiring
thermal desorption or biopiling would take between 2 to 3 years and cannot be
accommodated within the programme for Contract 2 on site works. Various other sites have therefore been
examined. A summary of the review
of these sites is given on Table 3.1. The site at Penny’s Bay is not
acceptable for treatment of other material because of the uncertainty of any
negotiations to secure the area from the Contractor for Contract 1 (Contract
No. CV/2000/09) which could undermine the planning and tendering of Contract 2
and jeopardize timely opening of the Theme Park. There is also the likelihood that the thermal desorption
plant at Penny’s Bay would still be operating in late 2005early 2006. If the thermal desorption plant was
operated at Penny’s Bay it would therefore need to be relocated to another
site, if available, prior to the opening of the Theme park to avoid
unacceptable risks to Theme Park visitors. The site at Tai Chuen is not acceptable because it is not
large enough for all the decontamination works requiring the use of multiple
treatment sites with wider risk and impact from transportation and duplication
of treatment. The only site at Siu Ho Wan identified is inadequate in size and is
also adjacent to the Siu Ho Wan Water Treatment Works and is therefore
not considered environmentally acceptable.
3.37.
The
review has determined that a suitable site at To Kau Wan is available for the
expected duration of the proposed decontamination works. The site at To Kwau Wan is 6.1ha and is
adequate to accommodate all the thermal desorption and biopile treatment works
on one site. The site is
reasonably close to Penny’s Bay and is to have temporary road access for the
transfer of contaminated material by truck. The site has also adequate marine access with an existing
vertical seawall and pier for the establishment of treatment facilities and
subsequent shipments of treated material off site. Transportation and storage impacts are estimated to be acceptably
low. Potential environmental
impacts associated with the decontamination works are acceptable and can be
mitigated as no sensitive land uses are located nearby (the
evaluation of environmental impacts and proposed environmental mitigation
measures are discussed in the relevant sections of this report). Accordingly it is recommended that the
site at To Kau Wan be used as the decontamination works site.
Table 3.1 : Summary of Review of Potential Decontamination Sites
|
Decontamination Works Area |
Site Area |
Site Availability |
Road Access |
Marine Access |
Existing Vertical |
Transportation Distance
(km) |
Programme |
Environmental Impact |
Remark |
|
|
Seawall (Berth) |
Land |
Sea |
|
|
|
|||||
|
Area
6B Penny’s Bay |
Potential Area of 4ha
subject to surrender by Infrastructure Contract 1 contractor |
Site is not available and
will be under control of Infrastructure Contract 1 Contractor from 1/03 to
4/05 (27 months). Requires
negotiation to effect a surrender of this works area. |
Yes |
Yes |
No |
2.9 |
N/A |
Plant to be relocated to
another site if treatment not complete by early 2005. Long lead time negotiation for
surrender of works area from Infrastructure Contract 1 contractor poses risk
to Contract 2 tender programme and project completion and Theme Park
opening. Surrender of 5ha works
area by Infrastructure Contract 1 may delay completion of Contract 1 works
and Theme Park opening. |
Potential impact on Site
Workers |
Not Recommended. |
|
To
Kau Wan |
6.1 ha Adequate |
Availability confirmed for
minimum 36 months. (1.7.02 till 30.6.05)1 |
Yes |
Yes |
|
3.6 |
N/A |
Allows for possible delays
in decontamination treatment without relocation |
Minimal Impacts. Acceptable impact on Toll Plaza
Administration Building. |
Recommended. |
|
Tai
Chuen |
1.65 ha Inadequate |
Currently available |
No |
Yes |
Yes |
N/A |
12 |
Allows for possible delays in
decontamination treatment without relocation. |
Potential Visual and Air
Quality Impacts. Close to Ma Wan
Fish Culture Zone. |
Not Recommended. |
|
Sui
Ho Wan |
2.61 ha Inadequate |
Currently reserved for
another project |
Yes |
No |
No |
(i) 7.0 |
N/A |
N/A |
Close to Siu Ho Wan Water
Treatment Works. Potential
Contamination of water supply. |
Not Recommended. |
|
|
Requires use of public
road. |
|
|
|
|
|
||||
Note : 1. Prolonged
use of part of site beyond 30.6.05 is believed to be possible. Discussions are underway with DLO/Is.
[1]
Sites outside North Lantau have been considered but were considered not
acceptable in view of the wider environmental impacts. One site considered was a Tsing Yi lot next to Tsing Ma Tourist
Centre. This site was not considered environmentally
acceptable. This is because of the
the potential
adverse visual and air quality impacts from the decontamination plant on the
tourists using the Tsing Ma Viewing Point and the bridge users.
