5.                      WATER QUALITY ASSESSMENT

5.1         Introduction

The Study Brief (ESB 068/2001) requires that a water quality assessment is carried out to identify the impacts of the construction works on water quality systems and receivers, to determine the extent of any changes to water courses and to assess the cumulative impacts due to other projects. The Brief also calls for an analysis of the provision and adequacy of existing and planned future facilities to reduce pollution arising from the non-point sources, to recommend best practices to reduce storm water and non-point source pollution sources as far as practical. Protection of the water gathering ground is paramount and an emergency contingency plan for construction and operational phases of the works is required to protect this resource.

This section outlines the potential impacts associated with the construction of the proposed cable car between Tung Chung and Ngong Ping. It encompasses the impacts associated with the construction of the towers and angle stations as well as the two termini. Operational issues which are addressed within the context of this EIA include the maintenance issues and disposal of liquid wastes, potential reuse of treated effluent from the Ngong Ping Sewage Treatment Works and the effects of restitution of the stream course which traverses the Ngong Ping terminal lot on the receiving habitats. The environmental acceptability of the impacts on receiving water quality and the receiving environment both during and following construction were determined and mitigation measures recommended where necessary.

It should be stressed at the outset that there are no alterations to watercourses proposed as a result of the provision of the terminal buildings or the towers or angle stations and no cumulative impacts on receiving waters.  The preferred alignment does not require a tower base to be founded in the Sea Channel (unlike some previous options) and thus no modelling is required to be undertaken and no gazettals are required under the Foreshore and Seabed Ordinance.

The water quality assessment has followed the guidelines given in Annexes 6 and 14 of the TMEIA.

5.2         Legislation, Standards, Guidelines and Criteria

The Water Pollution Control Ordinance (WPCO) (Cap. 358) enacted in 1980 is the principal legislation controlling water quality in Hong Kong along with Annexes 6 and 14 of the TMEIA.  Under the WPCO, Hong Kong waters are classified into 10 Water Control Zones (WCZs) and statutory Water Quality Objectives (WQOs) are specified for each WCZ.  This project falls within the catchment of the North Western Water Control Zone and while the stream courses ultimately drain into the Water Control Zone, for this project the following standards and guidelines are more relevant:

·           Water Supplies Department (WSD) guidelines on protection of Water Gathering Grounds, which are appended as Annex E; and

·           Practice Note Professional Persons on Construction Site Drainage.

 

The Practice Note for Professional Persons (ProPECC Note PN1/94) on Construction Site Drainage provides guidelines for the handling and disposal of construction discharges.  This ProPECC Note is generally applicable for control of site runoff and wastewater generated during the construction phase of the Project.  In particular the ProPECC Note covers the relevant aspects of:

-        surface run-off;

-        groundwater;

-        boring and drilling water from ground investigations etc;

-        wastewater from concrete batching and precast concrete casting;

-        wheel washing water;

-        bentonite slurries; and

-        wastewater from building construction and site facilities.

 

·           Technical Memorandum (TM), “Standards for Effluent Discharge into Drainage and Sewerage Systems, Inland and Coastal Waters”, issued under Section 21 of the WPCO defines acceptable effluent discharge limits to different types of receiving waters.

With regard to inland waters, there is no distinction between different zones and the beneficial use of the inland waters is the only factor governing the quality and quantity of the effluent that should be met. Under the TM, inland waters are sub-divided into four beneficial uses.  These are given below in Table 5.1.

Table 5.1  Different Groups of Inland Water Specified in the TM

 

Inland Water Grouping

Beneficial use

Group A

Abstraction for potable water supply

Group B

Irrigation

Group C

Pond fish culture

Group D

General amenity and secondary contact recreation

(Source: Adopted from Technical Memorandum of Standards for Effluents Discharged into Drainage and Sewerage Systems, Inland and Coastal Waters)

For this Project “Group A” waters prevail for the inland waters the WQOs which prevail are given in Table 5.2.

Table 5.2 Standards for Effluents Discharged into Group A Inland Waters          (All units in mg/L unless otherwise stated; all figures are upper limits                         unless otherwise indicated)

 

Flow rate

(m3/day)

Determinand

< 10

> 10

and

< 100

> 100

and

< 500

> 50

and

< 1000

> 1000

and

< 2000

pH (pH units)

6.5-8.5

6.5-8.5

6.5-8.5

6.5-8.5

6.5-8.5

Temperature (oC) 

35

35

30

30

30

Colour (lovibond units)

(25mm cell length)

1

1

1

1

1

Conductivity (mg/c, at 20oC)

1000

1000

1000

1000

1000

Suspended solids

10

10

5

5

5

Dissolved oxygen

> 4

> 4

> 4

> 4

> 4

BOD

10

10

5

5

5

COD

50

50

20

20

10

Oil & Grease         

1

1

1

1

1

Boron

2

2

1

0.5

0.5

Barium

2

2

1

0.5

0.5

Iron

2

2

1

0.5

0.5

Arsenic

0.05

0.05

0.05

0.05

0.05

Total chromium

0.05

0.05

0.05

0.05

0.05

Mercury

0.001

0.001

0.001

0.001

0.001

Cadmium

0.001

0.001

0.001

0.001

0.001

Selenium

0.01

0.01

0.01

0.01

0.01

Copper

0.2

0.2

0.2

0.2

0.1

Lead

0.1

0.1

0.1

0.1

0.1

Manganese

0.5

0.5

0.5

0.5

0.5

Zinc

1

1

1

1

1

Other toxic metals individually

0.1

0.1

0.1

0.1

0.1

Total toxic metals

0.3

0.3

0.2

0.2

0.15

Cyanide

0.05

0.05

0.05

0.05

0.02

Phenols

0.1

0.1

0.1

0.1

0.1

Hydrogen sulphide

0.05

0.05

0.05

0.05

0.05

Sulphide

0.2

0.2

0.1

0.1

0.1

Fluoride

1

1

1

1

0.5

Sulphate

800

600

500

400

200

Chloride

800

500

500

200

200

Total reactive phosphorus

1

0.7

0.7

0.5

0.5

Ammonia nitrogen

1

1

1

1

0.5

Nitrate + nitrite nitrogen

15

15

15

10

10

E. coli (count/100ml)

< 1

< 1

< 1

< 1

< 1

(Source: Adopted from Technical Memorandum of Standards for Effluents Discharged into Drainage and Sewerage Systems, Inland and Coastal Waters)

 

5.3         Background Water Quality

5.3.1             Potential Sensitive Background Water Quality

Water Courses

The water courses within the Study Area, illustrated in Figure 5.1, are relatively steep in the upland areas with alluvial fans just above the outfall to marine waters. The Study Area encompasses a Water Gathering Ground and the Lantau North Country Park which are perforce protected from the effects of pollution.  In the upland areas of the Lantau North Country Park water quality is still considered to relatively good as there are few sources of pollution and stream courses which have been surveyed as part of the ecological baseline surveys are discussed in Section 7.

In the Tung Chung area one of the predominant water features, which was conceived as an integral part of the overall North Lantau Development Plan, is the Sea Channel between Tung Chung and the new Airport at Chek Lap Kok.  The principle behind the design of the Sea Channel was to maintain water quality (and habitats) within Tung Chung Bay and to retain the natural coastal and hinterland drainage relief to the west of Tung Chung New Town.  This has been shown to be achieved over the last decade as the Sea Channel has been proven (by physical testing and monitoring) to be self cleansing and to encourage flushing of the East Tung Chung Bay.  As part of the ecological monitoring study, reported in Section 7, the ecological resources contained within the Sea Channel were surveyed. The results indicate good water quality by virtue of the habitats and diversity of ecosystems observed.

At the Ngong Ping terminal site a stream course runs through the site boundary and is being considered as a highlight of the Theme Village. While there are no records of the water quality in this stream, observations over a long period of time indicate that the water course is stressed through the effects of pollution primarily from domestic sources. The stream course does however feed into the upstream which is known to be a habitat for a population of Romer’s tree frogs. Plans to construct the Ngong Ping Sewage Treatment Plant and sewerage scheme will divert this source of pollution away from this stream in future (expected date of commissioning is July 2005 to accord with the opening of the cable car) and water quality is expected to improve greatly.

River Water Quality

As part of their routine monitoring programme EPD monitors the quality of water in the Tung Chung River. The upper catchment of the Tung Chung River is in the unsewered rural area where most dwellings have septic tanks and soakaways.  Domestic effluent is not discharged directly for the Tung Chung River.  The lower section of the river has been modified and lined to accommodate the developments of the Tung Chung New Town. Ultimately the Tung Chung River discharges into Tung Chung Wan which is part of the overall North Western Water Control Zone.

The most recently published results indicate 99% compliance with the Water Quality Objectives and a decreasing trend in nutrient levels over the last 8 years has been reported by EPD. The appellation given to the water quality in the river is “excellent”.

5.4         Potential Sources of Impact

5.4.1      Sources Inventory

Existing pollution sources within the Study Area are generally related to the domestic effluents generated by the Ngong Ping community, Tung Chung New Town and associated village houses. In keeping with the tenets of the new town development principle that no polluting industries would be located in the North Lantau Development Area, the pollution sources are therefore primarily from domestic, commercial and construction sources.

In the context of the cable car project the sources inventory must be divided into construction and operation phase. As identified in Section 2 there are various activities taking place which could potentially affect the water quality and impact on the water sensitive receivers. These are primarily:

Construction

·           construction of the terminals and tower bases where potential exists for offsite spillage into the receiving waters. There will be no direct discharge into the marine environment and for this assignment the concern relates more to the protection of water gathering grounds and stream courses and the Country Park resources;

·           wastewater generated by workforce and accidental spillage of materials; and

·           the construction works which could have the potential to cause offsite spillages include the use of concrete in the tower bases, potential spillages into the streams in the Country Park (NB it is not permitted to abstract water from the stream courses within the Country Park and the MTR contracts for construction of this project clearly state this); domestic sewage generated by the work force (at the remote tower bases as well as at the termini) and the excavation and reinstatement works associated with the stream course diversion at Ngong Ping.

Operation

·           washing the gondolas and maintenance issues including disposal of domestic effluent from the terminal buildings;

·           restitution of the section of the stream course which traverses the Ngong Ping terminal site; and

·           reuse of treated effluent from the Ngong Ping Sewage Treatment Works.

It should be stressed that no work will be undertaken in the marine waters of the Sea Channel and no component of the cable car system will impinge on the marine waters of the North Western Water Control Zone either during or following construction.

5.5         Sensitive Receivers

5.5.1      Beneficial Uses

Beneficial uses have been defined in accordance with the requirements of the Hong Kong Planning Standards and Guidelines (HKPSG), which have been transposed into the EIA-TM.  As required under the Study Brief all water bodies, water and stream courses, groundwater systems and other sensitive or beneficial uses have been identified within a 6km radius from the project site. Potentially sensitive receivers include:

·           the stream course at Ngong Ping and streams within the Country Park are potentially sensitive receivers and have been considered in the assessments (refer also to Section 7);

·           the Water Gathering Grounds as illustrated in Figure 5.2;

·           marine life which for this project essentially relates to that supported by the stream courses and is discussed in more detail in Section 7;

·           beaches and other recreational areas which essentially relates to the Sea Channel and San Tau although these areas are not directly affected by the works and can for the purposes of this assessment be disregarded as sensitive receivers; and

·           areas for navigation/shipping including typhoon shelters, marinas and boat parks which essentially encompasses the Sea Channel but as noted above this project does not directly, and only in extremis would indirectly, affect the Sea Channel.

5.6         Impact Assessment

5.6.1             Construction Phase

Construction of Towers

Potential water quality impacts associated with the construction of the towers will primarily relate to the use of concrete for the bases and pile rigs. Due to the site constraints, both physical and statutory, the Contractor will not be able to bring a concrete batching plant to the site instead he may select to bring ready-mix or to hand mix small volumes of concrete in-situ for the minimal volume of concrete which may be needed on-site. It is most likely that the tower bases will be precast and that the use of concrete will be limited to minor repairs/works at the bases. The Contractor will not be permitted to wash/rinse out any containers or materials contaminated with concrete or to discharge such wastewater to the receiving environment within the Country Park. Conditions will be specified in the Contract as well as in the environmental management plan.

Other activities which could cause water pollution include the spillages of materials or drips from the generators which would be expected to be required (for pumping imported water from the tank etc.) at each tower location. A special spill control plan will be prepared to take account of this potential impact and drip trays will be specified as requirements for the generators.

The third key area is that of domestic waste generation. There are expected to be 4-6 workers at each of the tower locations at any given time during working hours and mulching or chemical toilets (with waste disposal off-site) will need to be provided and maintained for use by all. Both the contract conditions and the environmental code of conduct for working on this project which has been developed by MTR (October 2002) state that the workers must also take all waste materials (lunchboxes, waste papers, construction wastes etc) out of the Country Park each evening. No fuels will be permitted to be stored in the Country Park thereby reducing the potential for accidental spillage while unattended.

Construction of the Termini

Although the final form of the terminal buildings has not yet been decided, general construction activities with the potential to affect water courses (either directly or via storm drains or foul sewers) may be categorised into excavation, concrete mixing, superstructure formation and fixing and cladding.

Excavations will need to be dug and depending upon the time of year these take place the potential exists for dewatering. In order to reduce the potential for dewatering the excavation should be planned, if possible, within the dry season. In any event any dewatering liquids will need to be treated on-site either by settling ponds or through use of a mobile filtration plant to reduce the level of suspended solids prior to disposal to comply with the water quality objectives.  Site runoff is also generally characterised by high concentrations of suspended solids and release of uncontrolled site runoff would increase the SS levels and turbidity in the nearby water environment. Bunds should be erected around the perimeter of the site at both Tung Chung and Ngong Ping (or within the working area) to direct the runoff to drains (via sandbags) rather than allowing uncontrolled flows offsite.

While it is not anticipated that concrete batching plants would be used for the two terminal buildings, due to the availability of concrete from the batching plant in Tung Chung and Mui Wo, the flexibility should be provided for the Contractor to decide his working methods. It should be noted that concrete batching plants and kitchen facilities are unlikely to be approved within the Water Gathering Grounds and WSD must be consulted and their agreement sought if the Contractor considers the installation of either facility.  In the event either of these two aforementioned facilities was approved inprinciple by WSD then the Contractor would be obliged to apply for and secure a licence under the Water Pollution Control Ordinance and to demonstrate that adequate measures were in place to ensure no washout water was discharged to the receiving environment without treatment.

Various other types of construction activities may generate wastewater or spillages and these primarily relate to the provision of the superstructures and use of fixings, paints, adhesives etc. Good site practices should be adopted to avoid and if necessary handle these materials.

Dust suppression measures are also recommended in Section 3 to minimise the air quality impacts. Caution must be exerted to ensure there is no overspraying at the terminal sites which could cause offsite runoff problems (although this is unlikely as contractors usually have to be encouraged to increase dust suppression measures).

Site management practices and bunding around the perimeter of the site will reduce the potential impacts.

Specific Protection of the Water Gathering Grounds

As noted above in connection with the discussion regarding the tower locations, temporary toilet facilities will need to be provided. Within the Water Gathering Ground (including Ngong Ping) the provision of such facilities is subject to approval of the Director of Water Supplies.  As a minimum requirement temporary toilet facilities must be located more than 30m from any watercourse. For all the tower bases and at Ngong Ping this requirement would not present any difficulty.

There will be four footings for each tower and the works site at each footing will be limited to approximate 5m x 5m. The scale of works site for tower is considered relatively small. At the tower locations within the Water Gathering Grounds there will be measures taken to minimise rainfall into the site (through erection of tent like structures over the tower bases to direct rain water off the tower footprint) and the perimeter of the work sites will be bounded to prevent ingress of rainfall during storm events; and to prevent off site migration of materials. The extent of the Water Gathering Grounds with respect to the project work sites/areas is demonstrated on Figure 5.2. With such measures in place, no water quality monitoring is required. The sites and working practices will be audited by the ET. In the event of rain storm and typhoon warnings, the Contractor shall ensure the measures are properly implemented in order to prevent erosion and run off from site which should be provided as a “response plan/ method statement.

There should be no kitchen or canteen facilities provided within the water gathering grounds. Again for the tower bases this is easy to control as the workers will be required to take their daily rations to site. As noted in the foregoing section, if there is a canteen installed on site at Ngong Ping then any wastewater would need to be collected in a separate storage tank for off-site disposal by a licenced waste disposal contractor (similar to the requirement for the temporary toilets).

Notices should be posted at conspicuous locations to remind the workers not to discharge any sewage or wastewater into the nearby environment during the construction phase of the project.  Environmental training and audits will provide an effective control of any malpractice.

 

5.6.2      Operational Impacts

Washing of Gondolas, Maintenance Issues and Domestic Effluent

Washing of the gondolas is expected to take place each evening once the service has closed to the public at the Tung Chung Terminal.  The gondolas are expected to be stored (except for three which may be strung across the Sea Channel to act as beacons, for compliance Airport Safety Requirements), in the maintenance hanger at the Tung Chung Terminal.  For the purposes of this assessment, it is assumed that washing will take place daily and will include weakly acidic wash for the bodies with “soapy” water washes for the windows.  It should be stressed that the whole purpose of ride is to enjoy the visual experience so clear vision is essential.  The maintenance area is expected to be designed as part of the building structure and the washing area will contain facilities somewhat akin to giant “car washes”.  The floor area will be bunded and drainage connected to the foul sewers, in accordance with the requirements of the Water Pollution Control Ordinance licence which will need to be sought from EPD prior to commissioning the facility.

Toilets will be provided at the termini for the comfort of passengers.  As the Ngong Ping Sewage Treatment Works (STW) has been designed taking account of the patronage of the cable car the disposal of domestic effluent will be to the facility (noting that the commissioning date of the STW has been matched to the opening of the Cable Car”).  At Tung Chung the effluent will connect to the existing sewerage system for Tung Chung which has the capacity to accommodate the small increase in domestic wastes generated by passengers and operators.

Restitution of the Stream Course at Ngong Ping

The stream course which traverses the site of the terminus at Ngong Ping is being considered as part of the developments at Ngong Ping Theme village as a highlight of the area. The restitution of the stream course to enhance its potential ecological value, through improvements to the banks (soft engineering) is seen as a benefit to the area. The detailed design of stream enhancement works in this small section (which does not involve diversion of the water course but rather a restitution of the banks and enhancement of the habitats) will be developed in due course. The design will avoid the use of concrete channels and will focus on a soft engineering approach as illustrated on Figure 5.3.  The design of the stream improvement works will need to be sized to accommodate the anticipated peak flows (without the contribution from the existing pollution sources of domestic wastewater) although the basic tenet of the restitution works is to enhance the ecological resources of the stream course rather than creating an engineered structure).

The profile of the stream course will include gentle sloping sides and meanders to encourage flow and to create areas of habitat interest. The water quality of the stream course will be greatly improved due to the reduction in point and non-point source pollution loads under the auspices of the Ngong Ping Sewage Treatment Works Project.

 

Non-point Pollution Sources

Non-point water pollution sources in the context of the cable car project primarily relate to the wash out of fertilizers or pesticides used in the landscaping works.  It should be stressed that no fertilizers or pesticides can be used in the Country Park or Water Gathering Grounds without first obtaining permission from AFCD or WSD respectively.  For the protection of the Water Gathering Grounds it is understood that WSD will not permit fertilizers or pesticides to be used in landscaping (Theme Village, Ngong Ping terminal) where there could be a connection of potential contaminants (through runoff) to the catchment.  This requirement will be included in the landscaping plans for the Ngong Ping terminal and the Theme Village.

In addition to the foregoing there should be a drainage plan prepared as part of the detailed design to collect runoff from those areas which may discharge to the Water Gathering Grounds (even indirectly) and which could otherwise convey suspended materials to the Water Gathering Grounds.  The plan should include interceptors and appropriate treatment as part of the overall water pollution protection plan for Ngong Ping and its environs.

Reuse of Treated Effluent

Waste water will be treated at the Ngong Ping Sewage Treatment Works using sequencing batch reactor (SBR) technology.  While no performance specification has been given it is expected that using this technology and the requirements of the Water Gathering Grounds, that a high quality effluent will be discharged.  Thus there is the potential application for re-use of the treated effluent for irrigating non-food crops only during the operational phase of the cable car.  The standards to be achieved for flushing and irrigation are given in Table 5.3 and will need to be carefully checked against treated effluent once the Ngong Ping Sewage Treatment Plant has been commissioned.  From a review of the available processes and literature it appears that the standards given in Table 5.3 can be achieved.  The issue to be addressed is the consistency of the quality of treated effluent from Ngong Ping Sewage Treatment Works, which is uncertain at present. 

Table 5.3  Effluent Reuse at MTRC Site, Ngong Ping for Flushing and Irrigation Effluent Standards (DRAFT)

Constituent

Units

aLimiting Standards

bTarget Standards

Colour

 

<20 H.U.c

15 T.C.U.d

Ammonia N

mg/l

<1

<1

Odour

T.O.N.e

<100

1

pH

 

-

6 to 8.5

Dissolved Oxygen

mg/l

>2

>2

BOD5

mg/l

10

-

Total Organic C

mg/l

-

<2

Total SS

mg/l

<10

-

Turbidity

NTU

<10

<5

E.coli

cfu/100ml

100

Non Detectable

Residual chlorine

mg/l

0.5

>0.5

Synthetic

mg/l

<5

<5

Detergents

mg/l

 

 

Note:

a     Limiting Standards are the minimum standards that the treated effluent must meet for reuse in Ngong Ping.

b     Target Standards are the standards that can be achieved with more advanced treatment technology.  These targets are for reference only.

c     H.U.        =    Hazen Unit

d     T.C.U.    =    True Colour Unit

e     T.O.N.    =    Threshold odour number

Source : As provided under cover letter reference EP20/08/83G(17)

For flushing water, the use of coloured pipes and fittings (e.g. use purple coloured pipes for conveying recycled treated effluent) to distinguish them from the potable water supply is recommended.  Addition of nontoxic dye such as methylene blue could also be recommended to the recycled treated effluent and monitoring and/or inspection programmes developed (to be agreed amongst MTRC, EPD, DSD and WSD) to routinely inspect the water supply systems.

For ornamental fountains, because of possible body contact with the public and aerosol generated from running water, a more stringent set of WQ standards would be required compared with the draft set of standards for flushing and irrigation use as listed in Table 5.3. Department of Health (HD) should be consulted if reuse of treated effluent for other than flushing or non-crop irrigation. Standards would be agreed among EPD, WSD and HD prior to use of any ornamental features and would most likely be the Standards applied to drinking water.  The principle behind this suggestion is that if one can drink the water, it must perforce be suitable for ornamental use.

If irrigation using recycled treated effluent is to be used the following safety measures should be considered for the protection of public health:

·           All pipes and fittings used for the irrigation system should be clearly marked (e.g. use purple coloured pipes for conveying reclaimed water) to distinguish them from the potable water supply.

·           Routine checking and/or inspect of the irrigation water supply systems for possible contamination should be carried out at a frequency to be agreed between MTRC, WSD and EPD.  The use of coloured (non toxic or non permanent) dyes may not be appropriate for irrigation systems given the visual impacts.

·           Signs should be permanently displayed informing employees, visitors and the public at large that treated effluent is being used.

·           To minimise public contact with aerosols during spray irrigation, the irrigated area should be secured and include warning signs to restrict public access when spraying. In addition, such irrigation should only be operated at night.

·           To minimise any residual impact on the public, the aerosol-forming irrigation devices, including sprinklers and sprays, should be designed to minimise aerosol generation and located away from the following:

(i)      Air condition and fan intake points;

(ii)      buildings or structures where food or drink is processed for consumption; and

(iii)     areas where the public can gain unimpeded access.  

·           This aerosol method should only be used at night time.

For non-aerosol forming irrigation (e.g. drip irrigation), the above restrictions need not apply except for the first 3 bullet points. Mitigation measures such as surrounding all landscaping with bunds or contained drainage channels should be included in the landscape design to minimise surface discharge during irrigation as well as to intercept and or retrieve the excess recycled treated effluent in order to prevent this reaching nearby stream courses.

In the event that treated effluent is considered for use at Ngong Ping, an action plan would need to be put in place.  This would include but not be limited to:

·           identify potential uses;

·           determine risks (to receiving environment, potential cross connections, hazards to general public etc.)

·           agree standards for specific categories of reuse (irrigation, ornamental fountains etc.) between MTRC, DSD, EPD and WSD;

·           define mitigation measures;

·           agree monitoring requirements between MTRC, EPD, DSD and WSD; and

·           develop detailed designs to include measures to intercept and collect surplus recycled treated effluent such that it can be re-circulated, measures to prevent storm water entering the system during the wet season and prevention of overspill to nearby watercourses will also be required.

5.6.3      Mitigation Measures

Water Gathering Grounds

The following are Conditions for Working within Water Gathering Grounds as specified by Water Supplies Department.  They will apply, through the permit process; in totality to the cable car project.

For all works within water gathering ground (WGG), the Contractor will be required to comply with the following conditions:

(a)     All practical measures shall be taken to ensure that no pollution or siltation occurs to the catchment.

(b)     No earth, building materials, fuel, soil or toxic materials or any other materials which may cause contamination to the WGG are allowed to be stockpiled on site.

(c)     No storage and discharge of flammable or toxic solvents, petroleum oil or tar and other toxic substances shall be allowed within the WGG.

(d)     Any spoil shall be reused wherever practical, in-situ and where unavoidable surplus material shall be removed from the WGGs as soon as practicable.

(e)     Temporary drains with silt/grease traps shall be constructed at the boundary of the site prior to the commencement of any earthworks.  The effluent from the drain shall comply with the standards of Group A Inland Waters as stipulated in the Technical Memorandum prepared by EPD on “Standards for Effluents Discharged into Drainage and Sewerage Systems, Inland and Coastal Waters”.  This will specifically apply at the Ngong Ping Terminal.

(f)      Regular cleaning of the silt/grease traps shall be carried out to ensure that they function properly at all times.

(g)     All excavated or filled surfaces which have the risk of erosion shall always be protected from erosion.

(h)     Facilities for washing the wheels of vehicles before leaving the site shall be provided.

(i)      Any construction plant which causes pollution to catchwaters or catchment due to leakage of oil or fuel shall be removed off site immediately.

(j)      Any soil contaminated with fuel leaked from plant shall be removed off site and the voids arising from removal of contaminated soil shall be replaced by suitable material to the approval of the Director of Water Supplies.

(k)     Provision of temporary toilet facilities shall be subject to the approval of the Director of Water Supplies.  All waste shall be cleared away daily and disposed of outside WGG.  The toilet facilities shall not be less than 30 m from any watercourse.

(l)      All mud and debris shall be removed from any Waterworks access roads and associated drainage systems.

(m)    Any chemicals to be used including fertifizers, disinfectants and deodorants within the WGG shall be subject to the approval of the Director of Water Supplies and MTRC.

(n)           For drainage and sewerage diversions within or affecting WGG, the agreement of the Director of Water Supplies is also required.

(o)           The use of pesticide is not allowed with WGG.

General Mitigation Measures

·           All waste water generated on the Site shall be collected, removed from Site via a suitable and properly designed temporary drainage system and disposed of at a location and in a manner that will cause neither pollution nor nuisance.

·           The Contractor shall construct, maintain, remove and reinstate, as necessary, temporary drainage works and take all other precautions necessary for the avoidance of damage by flooding and silt washed down from the Works.  He shall also provide adequate precautions to ensure that no spoil or debris of any kind is allowed to be pushed, washed down, fall or be deposited on land or on the seabed adjacent to the Site.

·           The Contractor shall not permit any sewage, waste water or other effluent containing sand, cement, silt or any other suspended or dissolved material to flow from the Site onto any adjoining land or allow any solid waste to be deposited anywhere within the Site or onto any adjoining land and shall have all such materials removed from the Site.

·           The Contractor shall be responsible for temporary drainage, diverting or conducting of open streams or drains intercepted by any works and for reinstating these to their original courses on completion of the Works.

·           The Contractor shall not discharge directly or indirectly (by runoff) or cause or permit to be discharged into any public sewer, storm-water drain, channel, stream-course or sea, any effluent or foul or contaminated water or cooling water without the prior consent of the relevant Authority who may require the Contractor to provide, operate and maintain at the Contractor’s own expense, within the premises or otherwise, suitable works for the treatment and disposal of such effluent or foul or contaminated or cooling or hot water.

·           The Contractor shall at all times ensure that all existing stream courses and drains within, and adjacent to the Site are kept safe and free from any debris and any excavated materials arising from the Works.  The Contractor shall ensure that chemicals and concrete agitator washings are not deposited in watercourses.

·           All Contractor’s Equipment shall be designed and maintained to minimise the risk of silt and other contaminants being released into the water column or deposited in other than designated locations.

To reduce water quality impacts from construction sites the Contractor will endeavour to:

·           reduce the amount of water used to dampen any surfaces or stockpiles;

·           prevent uncontrolled runoff from site by provision of perimeter drains at the seaward extremity of the sites in Tung Chung and to the streamcourse at Ngong Ping;

·           any liquid generated on-site should be treated and disposed of in accordance with the provisions of the Technical Memorandum (TM) on Standards for Effluents Discharged into Drainage, Sewerage, Inland and Coastal Waters (and shall be acceptable to MTRC/DSD/WSD/EPD).  Chemical or mulching toilets for tankering away the effluent or composting should be provided where there is no provision for making connection to the sewerage system;

·           all domestic effluent arising from the construction work force, any work camps, or canteen facilities should also be collected, treated and disposed of according to the provisions of the TM; and

 

·           any special works areas which may be provide for material storage or mixing, should be surrounded by bunds and have drainage collection systems to contain any spillages.

Chemical Wastes Disposal

Disposal of chemical wastes should be carried out in the compliance with the Waste Disposal Ordinance.  The Code of Practice on the Packaging, Labelling and Storage of Chemical Wastes published under the Waste Disposal Ordinance details the requirements to deal with chemical wastes.  General requirements include:

·           Suitable containers should be used to hold the chemical wastes to avoid leakage or spillage during storage, handling and transport; and

·           Chemical waste containers should be suitably labelled to notify and warn the personnel who are handling the wastes to avoid accidents.

Storage area should be selected at a safe location on site and adequate space should be allocated to the storage area.

Emergency Responses to Spillages

Emergency plans and clean up procedures will need to provided by the Contractor recognising his specific working methods and construction programme, activities and sequences.  Agreement must be sought prior to commencement of the construction work but the following principles should be considered. The emergency plans should include the procedures for:

·           spill prevention and precaution;

·           response actions; and

·           spill clean up and disposal.

Spill prevention and precaution embraces good site practice and covers:

·           good housekeeping practices;

·           chemical storage requirements; and

·           chemical transfer and transport.

Detailed response actions should be clearly stated in the emergency plans and training to implement the responses should be provided to all staff.  Emergency response plans should cover both construction and operational phases.  Emergency response plans will contain procedures, telephone numbers and actions/responses to “prevent an accident becoming an emergency”.  An outline Emergency Response Plan and clean up procedure is given in Table 5.4 as follows.  Detailed emergency plans and clean up procedures shall be agreed between MTRC/EPD/WSD before the commencement of the construction work.


Table 5.4   Emergency Response Plan

 

1.         Prevention and Precaution Measures

 

General Precautions

 

·         No water may be abstracted from water courses without first obtaining permission of Water Supplies Department and AFCD.

·         No discharge of silty water into watercourses.

·         All materials to be used during construction and operation shall be identified and their hazard potential evaluated.

·         All maintenance facilities shall be located outside the water gathering ground and should be on hard standings within a bunded area, with sumps and oil interceptors to be provided.

·         Maintenance of vehicles and equipment involving activities with potential for leakage and spillage shall only be undertaken with the areas appropriately equipped to control these discharges.

·         Any soil contaminated with chemicals/oils shall be removed from site and the void created shall be filled with suitable materials. (Washing the chemicals away is not acceptable as they have due potential to contaminate the water gathering ground).

·         No storage and discharge of flammable or toxic solvents, petroleum oil or tar and other toxic substances shall be allowed within the water gathering ground or Country Park.

·         Any construction plant which causes pollution to catchwaters or water gathering ground due to leakage of oil or fuel shall be removed off-site immediately.

·         Any chemicals to be used within the water gathering ground shall be subject to the approval of the Director of Water Supplies.

·         Suitable containers shall be used to hold the chemical wastes to avoid leakage or spillage during storage, handling and transport.

·         Chemical waste containers shall be suitably labelled to notify and warn the personnel who are handling the wastes to avoid accidents.

·         Storage areas shall be selected at safe locations on site and adequate space shall be allocated to the storage area.

·         Prevent obstructions and tripping hazards.

 

Storage Precautions

 

·         All chemical storage containers shall be correctly labelled.

·         Solid and impermeable enclosure walls or storage shelves shall be used.

·         Only compatible chemical wastes shall be stored in the same storage area.

·         The storage areas shall be inspected to detect any leakages or defective containers on a regular basis.

·         The condition of the storage containers shall be checked regularly.

·         Suitable notices warning of hazards, emergency response plans, telephone numbers etc shall be posted around the site, including storage areas.

·         Large and heavy containers shall be stored at ground level.

·         Chemical waste containers shall be stored below eye level.

·         Adequate space for handling of the containers shall be provided.

·         Spill response kits shall be located adjacent/near to the storage areas.

·         A log of chemical wastes shall be maintained.

·         Incompatible chemicals shall be stored separately.

 

Transfer and Transport Precautions

 

·         All containers must be sized to avoid overfilling.

·         Chemical wastes shall be transferred by pump instead of simply pouring.

·         Should leakage or spillage of chemical waste occur containment structures appropriate for the material spilled shall be provided.

·         Carriers shall be used to transfer the waste containers from one location to another.

·         Licensed waste collectors (also approved by MTR) shall be engaged to be responsible for chemical waste transport.

 

2.         Responses/Action Plan

 

All Workers shall be made aware of emergency telephone numbers and the location of all relevant pollution control equipment.  Training be given in emergency response/action plans. The action include the following steps:

 

·         Only trained personnel who are equipped with protective clothing and equipment shall be allowed to enter the spillage area for clean up.

·         Wherever appropriate, spills shall be transferred appropriate back into containers using suitable equipment.

·         Absorbent materials shall be used to clean up the spills and shall be disposed of as chemical wastes.

·         Where appropriate suitable solvents may be used to clean the contaminated area after removal of all contaminated materials.

·         MTR, Environmental Protection Department, Fire Services Department and Police shall be informed immediately in the event that spillage of chemicals could cause serious contamination of an area or risk of pollution. Immediately inform Water Services Department in the case where the spillage of chemicals could potentially cause contamination of the water gathering ground and AFCD for situations within the Country Park.

·         All necessary protective devices, safety equipment, containers and clean up materials for emergency use shall be maintained to a high standard.

 

3. Spill Clean Up and Disposal

 

·         Effect the response plan.

·         Control the leakage and absorb the spillage using suitably absorbent materials.

·         Provide safety equipment and personal protective equipment for handling of chemical wastes would be similar to that for handling of chemicals.

 

Safety equipment includes but is not limited to:

 

·         Fire extinguishers.

·         Spades, brushes, dustpan, mop and bucket (or similar readily available on site).

·         Absorbent material such as dry sand, tissues and toweling (all materials readily available on-site).

·         Containers including plaster bags, drums, etc.

·         Absorbing materials.

·         Pumps.

 

Personal protective equipment includes as appropriate:

 

·         First-aid kits.

·         Safety helmet and goggles.

·         Gloves which can resist chemical reaction.

·         Protective boot and clothing.

·         Respirators and gas masks.

·         Face visor and masks.

Once operational the conditions imposed on the cable car system preclude the need for specific emergency response plans per se.  However good practice suggests that the response plan should be maintained.

5.7         Residual Impacts

No residual adverse impacts are expected as a result of constructing or operating the cable car. The current construction programme for the Ngong Ping Sewage Treatment Plant matches with that of the cable car and assuming that all mitigation measures and precautions are taken for the construction of both projects no residual impacts are anticipated.

5.8         Conclusions

By implementation of the mitigation measures and adherence to the practice notes and codes of practice for work within the Country Park and Water Gathering Grounds, the water quality impacts are deemed to be acceptable. Inspections of the work sites and the stream course as part of the routine auditing of the works would be expected to be adequate for the protection of the water resources. However in the event of spillages or accidental discharges the emergency control plan would need to be implemented (with the agreement of MTRC/EPD/WSD/DSD) and checked for effectiveness.

The cable car project is anticipated to have minimal negative impact on water quality and indeed the assessment as demonstrated that there are benefits which could be accrued such as the improving of the stream course at Ngong Ping and also the potential for re-use of effluent from the Ngong Ping Sewage Treatment Works.