9.0              EVALUATION OF ALIGNMENT OPTIONS

 

9.1       Introduction

 

9.1.1          This Study has identified and investigated 4 alignment options, as discussed in the previous Sections, for the proposed 3 x 132kV circuits after a thorough assessment of the conditions and constraints within the Study Area as discussed in the previous Sections.  The proposed electricity circuits are to connect the Pui O Substation to Cheung Chau North and Cheung Chau South Substations by a mixture of transmission methods – overhead lines, underground cables, cable tunnel and submarine cables. There are a number of factors needed to be considered in the evaluation process for determining the preferred alignment option.

 

9.1.2     Of particular importance is the prediction and judgement of the significance of the effects of the route alignments on ecology, landscape and visual character, village residents and coastal lines of such an attractive area in south Lantau and Chi Ma Wan Peninsula. However, it should be noted that visual impact assessments, in particular, involve subjective opinion.

 

9.1.3     Apart from the environmental consideration, ‘statutory requirements and procedures’ is another important factor that needs to be taken into account.  The viability of the proposal depends on its full compliance with all necessary statutory procedures.  The more statutory requirements needed to be fulfiled, the longer the time it will take to complete the procedures.  The evaluation process should consider the time schedule set for the commissioning of the proposed electricity circuits.

 

9.1.4     The factors that have been considered in the evaluation process are shown in Table 9.1.  Different weightings have been assigned to different factors as shown in the Table.

 

            Table 9.1  Evaluated Factors and Weightings

 

Factors

Weightings

 

Landscape Impact

15

Ecological Impacts

10

Visual Impact

5

Statutory Requirements and Procedures

15

Land Requirements

10

Traffic Impact

10

Marine Impact

10

Construction Cost

10

Ease of Maintenance

10

Construction Impact

5

Total

100

 

 

 

 

 

 

 

 

 

Table 9.2    Evaluation of Alignment Options (Higher mark represents more favourable option)

 

Criteria

 

Evaluation

Mark

Landscape Impact

Option I –       This Option adopts overhead lines crossing Lantau South Country Park between Pui O Substation and Tai Long Wan East. Although the length involved is over 5km, only the construction of the concrete footings for the 18 metre high H-poles at isolated locations will require vegetation clearance.  The 33kV circuits will eventually be replaced by the 132kV circuits, and revegetation will be carried out on this corridor after the demolition of the 33kV circuits.

 

It is not expected that the underground sections in Cheung Chau Island will cause any significant landscape impacts.

 

6

 

Option IIa –  The length of overhead lines in this Option crossing Lantau South Country Park is approximately 2.35km between Pui O Substation and Wang Tong.  There will be another 0.5km of overhead lines in the mountain area on the north side of Cheung Chau Island.

 

Comparatively, this Option will have less ecological impact than Option I.

 

It is not expected that the underground sections in Cheung Chan Island will cause any significant landscape impacts.

 

8

 

Option IIb –    This option uses underground cables to lead the electricity circuit along South Lantau Road, Chi Ma Wan Road and to Pui O Beach.  No ecological impact is expected.

 

It is not expected that the underground sections in Cheung Chau Island will cause any significant landscape impacts.

 

15

 

Option III –    The first section of this Option is the same as Option IIb. 

                        

                         The tunnel from Pui O to Ha Keng will have no landscape impacts to the Lantau South Country Park apart from the minor impact at the two portal locations.

 

It is not expected that the underground sections in Cheung Chau Island will cause any significant landscape impacts.

 

13

Ecological Impact

Option 1 -    This alignment will have impacts on the key habitats including woodlands where adjacent to the Chi Ma Wan Reservoir and tall shrub on the east of Ham Tin Tsuen

 

Option IIa - This alignment will impact on tall shrub habitats at Wang Tong and on the north of Shap Long Kau Tsuen.

 

Option IIb - This alignment crosses small portion of tall shrub habitats at Ham Tin Tsuen.

 

Option III -  Similar to Option IIb

 

4

 

 

 

5

 

 

6

 

 

8

Visual Impact

Option I –        The 3 x 132 kV overhead transmission lines are proposed to run in a similar alignments as the existing 3 x 33kV O/H lines.

 

The first section of the overhead lines will be visible from Pui O Lo Wai Tsuen, Pui O San Wai Tsuen, Ham Tin Tsuen, Shap Long Kau Tsuen and passengers travelling along South Lantau Road.  A slightly larger visual impact compared to the existing 33kV overhead lines will result from the higher supporting poles of the 132kV circuits.

 

The alignments traversing the Lantau South Country Park will impinge on green belt, coastal protection zone and will be visible by the visitors to the Country Park.

 

1

 

Option IIa –    Since the length of the O/H lines involved in this Option is approximately half the length compared to Option I, visual impact caused by this Option  is less severe than Option I.

 

2

 

Option IIb –    This Option either adopts underground cables or submarine cables.  No adverse visual impact will be created.

 

5

 

Option III –     The visual impacts of this Option come from the portals of the proposed cable tunnel at Pui O and Tai Long Wan.  With appropriate mitigation measures, the residual visual impacts are not expected to be significant.

 

4

Statutory Requirements and Procedures

Option I – The required statutory requirements and procedures for this Option are :

·            Environmental Impact Assessment Ordinance – Detailed EIA is required;

·                           Foreshore and Seabed (Reclamation) Ordinance – Gazetting for the submarine cables is required;

·                           Country Park Ordinance – Consent from Country and Marine Parks Authority is required;

·                           Town Planning Ordinance – Permission for the installation of the electricity circuits within green belt, coastal protection areas;

·         Permit for work from Marine Department for the submarine cables; and

·         Excavation Permit from Highway Department for installing the cables in public roads and footpaths at Cheung Chau.

 

As the alignment under this Option will significantly encroach upon the Country Park, the time for complying the EIAO and CPO will be very long.

 

5

 

Criteria

Evaluation

Mark

 

 

Option IIa  – The required statutory requirements and procedures for this Option are the same as Option I. As the encroachment of this alignment upon the Country Park is less significant, the time for complying the EIAO and CPO will be shorter than that for Option I on its impacts on Country Park.  However, as this alignment might disrupt the fish farm off the coast of Chi Ma Wan, consultation with AFD and The Fishermen Association is required.  The length of the submarine cables will also be a concern of EPD regarding the adverse effects on water quality that will result from the construction work.

 

6

 

Option IIb  – The required statutory requirements and procedures for this Option are the same as Option I. As the encroachment of this alignment upon the Country Park is less significant, the time for complying the EIAO and CPO will be shorter than that for Option I on its impacts on Country Park.  However, the length of the submarine cables will also be a concern of EPD regarding the adverse effects on water quality that will result from the construction work.

 

7

 

Option III  – The required statutory requirements and procedures for this Option are the same as Option I. As the encroachment of this alignment upon the Country Park is less significant, the time for complying the EIAO and CPO will be shorter than that for Option I on its impacts on Country Park.  The length of the submarine cables under this Option is much less than those under Option IIa and IIb, i.e. less concern from EPD.

 

10

Land Requirements

Option I  – The length for the 132kV circuits in Chi Ma Wan Peninsula traverse South Lantau Country Park is 5km, each circuit require a corridor width of 15m including clearance for vegetation.

 

9 nos submarine cables will be used. Each individual cable is 2.5km long approximately and require 50m wide corridor.

 

The underground cables in Cheung Chau will be laid in public roads, such as Cheung Kwai Road, Sai Wan Promenade.

 

7

Option IIa  – The length for the 132kV circuits in Chi Ma Wan Peninsula between Pui O Substation and Wang Tong is 2.5km, each circuit require a corridor width of 15m including clearance for vegetation.

 

9 nos submarine cables will run along Chi  Ma Wan, Cheung Sha Wan and connect to Cheung Chau North Substation. Each individual cable is approximately 4.8km long and will require 50m wide corridor.

 

The underground cables in Cheung Chau will be laid in public roads, such as Cheung Kwai Road, Pak She Praya Road , Tai Hing Tai Road, Sai Wan Promenade.

 

 

 

6

Criteria

Evaluation

Mark

 

Option IIb  – The length for the 132kV underground cables that run along South Lantau Road, Chi Ma Wan Road is 2.9km long.

 

9 nos submarine cables will run along Pui O Beach, Mong Tung Wan to Cheung Chau North and South Substations. Each individual cable is approximately 7.7km long and will require 50m wide corridor.

 

The underground cables in Cheung Chau will be laid in public roads, such as Pai Chong Road, Sai Wan Promenade etc.

 

8

Option III  – The length for the 132kV underground cables that run along South Lantau Road, Chi Ma Wan Road is 2.9km long.

 

Cable tunnel in Chi Ma Wan peninsula is 3.3km. Tunnel portals and will be located at east side of Pui O Beach and Tai Long Wan. A small reclamation will be required at Pui O Beach for portal construction.

 

The underground cables in Cheung Chau will be laid in public roads, such as Cheung Chau Sai Tai Road, Tai Hing Tai Road, Praya Street, Pak She Praya Street etc.

 

6

Land Traffic Impact

Option I –        Only a very small length of the circuits under this Option will cross Chi Ma Wan Road  and its impact on the land traffic is quite limited.

 

Since there is no vehicular traffic in Cheung Chau Island, the proposed underground cables in Cheung Chau Island via Cheung Kwai Road and Sai Wan Promenade would not be significant. Impact caused to pedestrian could be minimized by providing alternative accesses on site.

 

8

 

Option IIa –   No interruption of land traffic along Chi Ma Wan Road will occur under this Option as it adopts O/H lines for the first section.

 

The two circuits that pass through the busy streets in Cheung Chau Island north would cause significant impacts to pedestrians. These roads include Pak She Praya Street, Tai Hing Tai Road and Cheung Chau Sai Tai Road.

 

6

 

Criteria

 

Evaluation

Mark

 

Option IIb – Open excavation will likely be adopted for the proposed underground sections along South Lantau Road and Chi Ma Wan Road between Pui O Substation and Pui O Beach. Temporary traffic arrangements are required. This would cause inconvenience to the local residents and visitors to south Lantau.

 

However, if the installation works can be incorporated into the contract for Chi Ma Wan Road widening works which is due to commence in end 2000, the impacts can be absorbed into the roadworks.

 

In Cheung Chau Island, one circuit will run along Pai Chong Road and Pik Chong Road to the Cheung Chau North Substation and will cause impacts to residents.   At Sai Wan Promenade, the impacts will be less significant as its width is sufficient for maintaining the pedestrian access while construction work is carried out.

 

4

Option III –  The land traffic impacts at Pui O area is similar to that in Option IIb.

 

In Cheung Chau Island, the two circuits that pass through the busy streets would cause significant impacts to pedestrians. These roads include Cheung Chau Sai Tai Road, Tai Hing Tai Road, Praya Street, Pak  She Praya Street.

 

5

Marine traffic impact

Option I –        There will be 9 submarine cables in 3 sets crossing Adamasta Channel. Two sets of circuits, 2.5km long, will link up Tai Long Wan East to Cheung Chau south. Whilst the remaining one circuit, 1.7km long will link up Ha Keng to Cheung Chau north.

 

Adamasta Channel is the major navigation fairway for ferry between Hong Kong and Macau. It is anticipated that interruption to marine traffic will be inevitable and prior arrangement with Marine Department for the marine traffic diversion is required.

 

Ferries from Central to Cheung Chau are frequent. However, the alignments of the two circuits connected to Cheung Chau south via Tung Wan Typhoon Shelter and Promenade will be off the regular ferry route and hence, interruptions to the ferry services could be minimized.

 

5

 

Option IIa –    There will be 9 nos. submarine cables in 3 sets, each approximately 4.8km long, to be laid under this Option between Chi Ma Wan and Cheung Chau North.

 

Apart from the interruptions to the marine traffic in Adamasta Channel as started in Option I. Disruptions to ferry services between Central to Cheung Chau, Cheung Chau to Chi Ma Wan are likely.

 

3

 

Criteria

 

Evaluation

Mark

 

Option IIb –    There will be 9 nos. submarine cables in 3 sets to be laid under this Option from Pui O beach to Cheung Chau south (2 sets of approximately 7.7km) and Cheung Chau north (1 set of approximately 7.8km).

 

This is the longest submarine route compared with other options, the alignments will run in the sea area off Mong Tung Wan, Tsui Pai, Shui Pai and across Adamasta Channel to Cheung Chau.

 

In addition to the interruptions caused to the marine traffic in Adamasta Channel as stated in Option I. The alignment will also cause disruption to visitors using the bays and beaches along the west coast of Chi Ma Wan Peninsula.

 

3

Option III –     There will be 9 submarine cables in 3 sets crossing Adamasta Channel from the east headland of Tai Long Wan. The circuits, 2.3km long, will be connected to Cheung Chau south. 

 

Ferries from Central to Cheung Chau are frequent. However, the alignments of all circuits will be off the regular ferry route and hence, interruptions to the ferry services can be avoided.

 

Part of the north end of the south breakwater of Chueng Chau Typhoon Shelter will need to be removed for submarine cables laying. It may cause interruptions to the marine traffics using the ingress and egress in proximity.

 

6

Construction Cost

Option I –        Overhead lines in Chi Ma Wan Peninsula 5km

 

                          Submarine cables across Adamasta Channel 2.5km

 

                          Underground cables in Cheung Chau Island is 1.5km.

 

                          It is estimated that this is the cheapest option.

 

8

Option IIa –    Overhead lines in Chi Ma Wan Peninsula 2.85km

 

                          Submarine cables across Adamasta Channel 4.8km

 

                          Underground cables in Cheung Chau Island is 2.2km.

 

                          It is estimated that this is the second cheapest option.

 

6

Option IIb –    Underground cables in Pui O area 2.9km

 

                          Submarine cables across Adamasta Channel 7.7km

 

                          Underground cables in Cheung Chau Island is 0.55km.

 

                          It is estimated that this is the second highest option.

 

6

 

Criteria

Evaluation

Mark

 

Option III –     Underground cables in Pui O area 2.9km

 

                          Cable tunnel in Chi Ma Wan Peninsula 3.3km

 

                          Submarine cables across Adamasta Channel 2.3km

 

                          Underground cables in Cheung Chau Island is 1.35km.

 

                          This option involves construction of both cable tunnel and submarine cables. It is estimated that this is the most expensive option.

 

4

Ease of  Maintenance

Option I –       The conductors of the overhead transmission lines traverse Chi Ma Wan Peninsula are near seashore and exposed to potential corrosion.  Maintenance and routine inspections would be expected at a higher frequency.   Helicopter will need to be used for carrying out the maintenance works.

 

Maintenance and repair of submarine cables are expensive and difficult.  This Option has the shortest length of submarine cables.

 

5

 

Option IIa –   The length of overhead lines is approximately half of that in Option I.  However, the length of submarine cables are nearly twice that in Option I.

 

5

 

Option IIb – A substantial length of the circuits under this Option is underground cables.  Any maintenance work required will be simple to carry out although it will create inconvenience to villagers in Pui O Lo Wai Tsuen, Pui O San Wai Tsuen, Ham Tin Tsuen, Chi Ma Wan as well as other road users who visit south Lantau.

 

The length of submarine cables in this Option is the longest.

 

4

 

Option III –  The underground section in this Option is similar to that in Option IIb.

 

Maintenance work will be simple for the section of the circuits accommodated in the cable tunnel under this Option.

 

The length of the submarine cables in this Option is similar to that in Option I.

 

8

 

Criteria

 

Evaluation

Mark

Construction Impacts

Option I –       The construction of the overhead lines under this Option will cause dust and noise, particular from helicopters, to the nearby residents.  However, the cable route is aligned  at a certain distance from the major villages.

 

The water quality is expected to be affected during the construction of the submarine cables.

 

The construction of the underground cables in Cheung Chau Island will also caused dust and noise to the residents in Cheung Chau.

 

 

2

 

Option IIa –    Construction impacts similar to Option I will occur in Option IIa.  However, this Option has a shorter overhead line but longer submarine cables.  Major disruption to existing dwellings would occur at Wang Tong and Chi Ma Wan Beach.

 

The submarine section will pass the fish farm off Cheung Sha Wan.  The construction work may worsen the water quality and affect the operation of the fish farm.

 

Overhead transmission lines will be used between the northern part of Cheung Chau and Tai Kwai Wan and continue with underground cables.  The two circuits will pass through Pak She Praya Street, Tai Hing Tai Road and Cheung Chau Sai Tai Road. These are the busiest main streets in Cheung Chau Island leading to the ferry pier. Space is limited and impacts caused by the construction on residents and visitors at these locations may be significant.

 

1

 

Option IIb –    The construction of the first section of underground cables along South Lantau Road and Chi Ma Wan Road will cause dust and noise nuisance to the villages and business operations on both sides of the Roads.  Visitors to the area and Pui O Beach will also be affected by the cable laying work.

 

The submarine section involved in this option is the longest although there are no other major facilities such as fish farm along the route.

 

Underground cables are proposed in Cheung Chau Island. Major construction impacts will occur along Pai Chong Road and Pik Chong Road for the construction of the circuit to Cheung Chau North Substation.  The widths of the roads are quite limited, particularly Pai Chong Road where shipyards and mechanic workshops are located.

 

1

 

Criteria

Evaluation

Marks

 

 

Option III –     The construction impacts for the first section underground cables are similar to that in Option IIb.

 

The construction impacts of the cable tunnel will be minimal except at the two portal locations. 

 

The length of the submarine cables is comparable to Option I with similar construction impacts.

 

Underground cables are proposed in Cheung Chau Island. Major construction impacts will occur along Cheung Kwai Road for the construction of the circuit to Cheung Chau North Substation.   The width of Cheung Kwai Road is quite limited and impacts to residents may be severe.

 

3

 

9.2       Conclusion

 

9.2.1          Table 9.3 summarises the ratings for different alignment options for the proposed 3 x 132kV electricity circuits.

 

Table 9.3  Summary of the Evaluation

 

Criteria

Weighting

Option I

Option IIa

Option IIb

Option III

Landscape Impact

15

6

8

15

13

Ecological Impact

10

4

5

6

8

Visual Impact

5

1

2

5

4

Statutory Requirements and Procedures

15

5

6

7

10

Land Requirements

10

7

6

8

6

Land Traffic Impact

10

8

6

4

5

Marine Traffic Impact

10

5

3

3

6

Construction Cost

10

8

6

6

4

Ease of Maintenance

10

5

5

4

8

Construction Impact

5

2

1

1

3

 

100

51

48

59

67

 

9.2.2          From the result of the evaluation, Option III which adopts cable tunnel to cross Chi Ma Wan Peninsula is the preferred alignment option.