2    Recommended site & Disposal Option

 

2.1    Introduction

 

This Section presents the recommend site and disposal option based on the environmental performance of the East of Sha Chau and South Brothers Facilities presented in Part 4, Section 1.  Impacts to marine traffic due to the construction and operation of the facility are reviewed, as are potential cost implications.  Based on a review of the above, the recommended site and disposal option is presented

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2.2    Preferred Facility Based on Environmental Performance

 

An evaluation of both the East of Sha Chau and South Brothers Facilities has been undertaken to determine the acceptability of the environmental impacts associated with their development and operation.  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 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 (see Annex A). 

 

If 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. 


2.3    Implication to Marine Traffic

 

A Marine Traffic Impact Assessment (MTIA) has been conducted for the proposed construction and operation of the East of Sha Chau and South Brothers Facilities.  The MTIA has been conducted to identify if the risk associated with traffic activity falls within acceptable levels.  The complete assessment is presented in Annex F.  The key findings of the assessment are detailed below.

 

2.3.1    Hazard Identification

 

A review of the existing constraints and hazards has been conducted and the summarised as follows:

·                Current operations, and future proposed sites are set south of the Urmston Road, adjacent to restricted waterspaces associated with the HKIA.

·                The East of Sha Chau Facility will be subject to very similar currents to those that impact the present operations.  However, currents within the South Brothers Facility will be significantly less.  It may also be concluded that the South Brothers Facility is considerably less exposed to wave impacts than the East of Sha Chau Facility.

·                It is apparent that periods of very low visibility (<1.0 km) are rare, with only 0.4 days per year being impacted in this manner.

·                There are approximately 1,500 vessel movements per day through the waterspaces adjacent to the sites.

·                The historic level of activity associated with disposal and capping operations (at an average of 16 movements per day) equates to approximately 1% of marine traffic within the Study Area.

·                Operations to date have been conducted in a safe manner.

 

2.3.2    Risk Assessment

 

A risk assessment of the proposed East of Sha Chau and South Brothers Facility has been conducted.  The following conclusions have been developed.

 

·                A baseline risk assessment has been carried out to correlate local traffic density and annual collision rates and so to provide a tool for the assessment of future risks.  Such a relationship has been identified, and the good accuracy is considered to provide a satisfactory and reliable foundation for the assessment of the future disposal activity.

·                From the time horizon of the Study (2005-2014), the peak year 2008 and 2010 scenarios were selected for the Quantitative Risk Assessment of the risk to life in associated with the proposed disposal activity.  For each of these years, it is identified that the hazard to life falls well within the acceptable level.  Hence, no specific mitigation measures are required for the disposal activity at the proposal facilities.

·                This finding is consistent with the perception of marine safety in the region of present disposal activity.

 

2.3.3    Summary

 

There were few apparent differences in risk levels between the East of Sha Chau and South Brothers Facility, with the former presenting marginally lower risks.  It is important to note that both present and future risk levels for both facilities fall well within acceptable limits and that this finding is consistent with the perception of marine safety in the region of present disposal activity. 

 

However, while the risk assessment projects that future risks will be acceptable, this is dependent upon the continued vigilance of the operator in the safe conduct of the disposal activity.

 

2.4    Cost Implications

 

The preliminary design of the contaminated mud disposal facility at East of Sha Chau and South Brothers has been based around the assumption that a minimum of 8 Mm3 of contaminated sediments can be accommodated in each area.  Cost implications are divided into capital and recurrent costs.  These implications are discussed below and apply to each facility.

 

2.4.1    Capital Costs

 

The estimates of capital cost have been based on the assumption that grab dredgers sourced from the local fleet will undertake all dredging operations.  The following assumptions have been made for each facility with respect to use and disposal of the materials dredged to form the pits:

1.             All material dredged from the first pit (Pit A) will be taken off-site for disposal;

2.             All material dredged from the second pit (Pit B) will be taken off-site for disposal or used to cap Pit IVc at East of Sha Chau;

3.             A proportion of the material dredged from the third pit (Pit C) will be used to cap Pit A, the remainder will be taken off-site for disposal;

4.             A proportion of the material dredged from any fourth pit (Pit D – East of Sha Chau only) will be used to cap Pit B, the remainder will be taken off-site for disposal;

5.             Capping of Pits C and D will be undertaken with material dredged from elsewhere in Hong Kong.  This material is assumed to be delivered to the site at no cost (ie. the cost will be borne by the donor project); and

6.             Capping does not include the top-up volumes required to restore the original seabed levels.  The practicality of doing this during the facility operational lifetime of the facility will need to be assessed after detailed design studies have been completed but, if it is possible, it would result in only minor cost savings of the order of $2 to 3 million.

 

Capping costs (excluding the cost of dredging the material used for capping) are estimated to be HK$ 13 per m3.  Dredging costs vary between approximately HK$ 8 and HK$ $17 per m3, depending on the depths from which the material is dredged and the destination of the dredged material (ie. use as capping material in adjacent pits or remote off-site disposal).  An additional 30% is added to all costs to cover construction overheads (profit, risk, establishment costs etc) and a further 2.5% to the total to cover supervision costs. 

 

In summary, based on the above assumptions the contaminated mud facility has been estimated to cost approximately HK$ 25/m3, equating to a potential total of HK$ 200M.

 

2.4.2    Recurrent Costs

 

Recurrent costs include management and EM&A and are estimated to be of the order of HK$ 25M per year for the duration of operations.  It should be noted that in addition, periodic surveys to check the condition of the capped pits would be required after the facility is closed.

 

2.5    Recommendation

 

The comparison of facilities based on their environmental performance indicated that both facilities are of equal environmental performance.  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.

 

The result of a marine traffic impact assessment on both sites also indicates that the South Brothers Facility presents marginally lower risks when compared to the East Sha Chau Facility. 

Costs for both facilities have been calculated to be the same. 

 

Based on the above, the multi-pit purpose-dredged Contained Aquatic Disposal facility (CAD) at East of Sha Chau is recommended for detailed design and implementation.  Should 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.  If 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. 


Contents

2  Recommended site & Disposal Option  1

2.1  Introduction  1

2.2  Preferred Facility Based on Environmental Performance  1

2.3  Implication to Marine Traffic  2

2.4  Cost Implications  3

2.5  Recommendation  4