1 Predicted environmental
Performance of Each Facility
1.1
Introduction
This Section highlights the predicted environmental performance
of the two facilities based on the information presented in Parts 2 and 3
and recommends the preferred facility.
The information presented here will feed into Section 4 that also
incorporates information on marine traffic impacts and cost implications.
1.2
Comparison of Facilities
In the comparison of facilities it is important to note that
under the Strategic Assessment and Site
Selection Study for Contaminated Mud Disposal (Agreement CE 105/98), a
detailed review of potential sites for a new contaminated mud disposal facility
was undertaken throughout Hong Kong waters. The study recommended that a site within the area East of
the Airport be taken forward as the preferred site for such a facility.
Although members of ACE had no objection to proceeding with
the site, they considered that the remaining portions of East of Sha Chau
should still be considered. As
such, this study has investigated the potential of the two areas to accommodate
a new contaminated mud disposal facility.
Despite the proven acceptability and close proximity of the
existing facility at East of Sha Chau, the purpose of the assessment was to
thoroughly evaluate both the East of Sha Chau and South Brothers Facilities in
terms of acceptability of predicted impacts to water quality, marine ecology,
fisheries, hazard to health, noise and cultural heritage from dredging,
backfilling and capping of the pits, as well as that from concurrent
activities. Through this
assessment, differences in the potential environmental performance of each
facility have become apparent.
These are discussed below.
Through the adoption of currently acceptable dredging,
backfilling and capping rates, the construction and operation of either the
East of Sha Chau or the South Brothers Facilities would result in only minor
exceedances of the Water Quality Objectives. In terms of impacts to sensitive receivers, these
exceedances would be likely to occur at the Airport Exclusion Zone Artificial
Reef through the construction and operation of the South Brothers Facility and
in the marine waters to the east of the boundary of the Sha Chau and Lung Kwu
Chau Marine Park for the East of Sha Chau Facility. In terms of acceptability, it is considered that the potential
impacts to the waters adjacent to the Marine Park would be of a slightly higher
concern than those to the Artificial Reef however both impacts are considered
to be minor .
1.3
Preferred Facility
A detailed evaluation of both the East of Sha Chau and South
Brothers Facilities has been undertaken to determine their relative suitability
for the development of a contaminated mud disposal facility in terms of
environmental impacts. Due to
potential planning constraints on the North Lantau coastline, such as the
landing point of the North Lantau Highway Connection of the Hong Kong Section
of the Hong Kong Zhuhai Macau Bridge and the proposed reclamation of the Lantau
Logistics Park, it is proposed that to avoid the possibility of cumulative
impacts occurring during the construction of new developments, East of Sha Chau
would be the preferred site.
It is important to note, however, that in terms of overall
impacts, both facilities are considered to be acceptable on the grounds that
both meet the relevant assessment criteria. Should specific pits within the area currently selected for the East of Sha Chau
Facility not be available when required, unacceptable
adverse impacts associated with proceeding sequentially with the South Brothers
Facility, if considered necessary, would not be expected to occur.
In order to verify this assumption, a review of potential
impacts to water quality from increases in suspended sediments arising from
operating the East of Sha Chau Facility concurrently with the South
Brothers Facility sequentially after the East of Sha Chau Facility has been conducted (Annex
A). The findings indicated that no adverse impacts would be expected to water
quality sensitive receivers when compared to the allowable increases as defined
by the WQO.
It should be noted,
however, that the assessment has been conducted on maximum operations without
the use of operational controls and include the potential impact from other
concurrent projects, such as disposal in the North Brothers Facility.
This conclusion is proposed with the caveat that no
works proceed with Pit C due its relative proximity to the mouth of Tai Ho Bay,
the landing point of the
North Lantau Highway Connection
the Hong Kong Section of the Hong Kong Zhuhai Macau Bridge and the
proposed reclamation of the Lantau Logistics Park.Inf proceeding
with the South Brothers Facility, it is recommended that, following the guidelines
of the EIAO TM, the precautionary principle be applied and operations in
Pit A should be activated first.
Activity in Pit B should only proceed if monitoring results for Pit A
demonstrate sufficiently the acceptability of environmental impacts. In addition, due to the proximity of
Tai Ho Bay and the, at present, uncertainty in the landing point of the North
Lantau Highway Connection of the Hong Kong Section of the Hong Kong Zhuhai
Macau Bridge and the proposed reclamation of the Lantau Logistics Park,
operations at Pit C should be avoided following the precautionary
principle.
The
uncertainties of the developments in the area and the potential for arisings of
contaminated mud to change present us with 3 options. These are presented below.
A tentative programme of the above three
available options is presented in the following sectionsworks is presented
in Figure 1.3a. It
should be noted that the timelines presentedts
predicted timeframes for each works component.
Option
1
The first option would be to construct and operate
the 4 proposed mud pits
A, B, C and D at East of Sha Chau. This option provides sufficient disposal capacity for existing
predictions of Contaminated Mud arisings. The timeline and sequencing is presented in Figure
1.3a. The
environmentally acceptability of this option has been confirmed in Part 3
of this report.
Figure 1.3a Tentative Programme of Works
for Option 1
Option
2
Option
2 assumes that planning constraints in the area
do not allow for the construction and use of East of Sha Chau pits A and
B. This option therefore employs
the use of East of Sha Chau Pits C and D followed by the use
of South Brothers pits A and B.
This option provides enough capacity for arisings that are currently predicted
between now and 2015. The
timeline and sequencing is presented in Figure 1.3b. The
environmental acceptability of this option has been confirmed in Annex A
of this report.
Figure
1.3b
Tentative Programme of Works
for Option 2
Option
3
Option
3 provides the highest capacity and allows for higher than expected arisings
to occur. This option involves the
use of the four East of Sha Chau pits A, B, C and D followed by
the South Brothers pits
A and B. The amount of time allocated
to backfilling
of the pits is shorter in the work programme to represent the higher
than
expected arisings. The timeline and sequencing is
presented in Figure 1.3c. The environmental acceptability of
this option has been confirmed by the modelling works presented in
Annex
A. It is noted that the modelling works
have assumed higher dredging, backfilling and capping rates than those that
would occur following the timelines
presented in the schedule.
Figure
1.3c
Tentative Programme of Works
for Option 3
For options 2 and 3 it is recommended that before
construction and activation of
the pits at the South Brothers, a review and update of the EIA should be
conducted to assess the validity of the assumptions made in
this EIA report.
Although
it has been shown that all 3 options are environmentally acceptable
(see Annex A),
Option 1 is recommended
as it best represents the needs of the present situation.n.
