6                             Water Quality Impact Assessment

6.1                       Introduction

6.1.1                 This section on Water Quality Impact Assessment (WQIA) is prepared in response to Section 3.4.6 and Appendix D1 of the EIA Study Brief which specify the requirements of WQIA.

6.1.2                 According to EIA Study Brief 3.4.6, the Study Area for WQIA shall include areas within 500 m from the boundary of the Project Site, see Figure 6-1-1 and Victoria Harbour (Phase 1 and Phase 2) Water Control Zone under Water Pollution Control Ordinance (WPCO), see Figure 6-1-2 and as follows:

Phase 1 of Victoria Harbour Water Control Zone (WCZ V1) covers:

l   Tsuen Wan East and Kwai Chung

l   Ma Yau Tong and Kwun Tong

Phase 2 of Victoria Harbour Water Control Zone (WCZ V2) covers:

l   Sham Shui Po

l   Yau Ma Tei, Tsim Sha Tsui, Mong Kok, Kowloon City and Wong Tai Sin

6.1.3                 It is obvious that only Kwun Tong, Kowloon City and Wong Tai Sin needs to be addressed as the Project influence are likely to be affected while that on other areas in WCZ V1 and WCZ V2 are insignificant and excluded in this assessment. Thus, the water bodies in To Kwa Wan Typhoon Shelter (TKWTS) and Kai Tak Approach Channel (KTAC) will be studied.

6.1.4                 In general, the WQIA shall follow the requirements as stated in WPCO, Appendix D1 of the Study Brief and Annex 6 (Criteria for Evaluating Water Pollution) and Annex 14 (Guidelines for Assessment of Water Pollution) to the Technical Memorandum (TM) on Environmental Impact Assessment Process. Other standards include:

l   Technical Memorandum on Standards for Effluents Discharged into Drainage and Sewerage Systems, Inland and Coastal Waters (TM-DSS) or in short, Technical Memorandum on Effluent Standards;

l   Hong Kong Planning Standards and Guidelines (HKPSG);

l   Water Supplies Department (WSD) Water Quality Criteria;

l   WSD’s “Technical Specifications on Grey Water Reuse and Rainwater Harvesting” and

l   Practice Note for Professional Persons (ProPECC), Construction Site Drainage (PN 1/94)

6.1.5                 This WQIA makes references to relevant WQIA of the following EIA reports:

l   Kai Tak Development (No. AEIAR-130/2009) (KTD EIA)

l   Dredging Works for Proposed Cruise Terminal at Kai Tak (No. AEIAR-115/2007)

l   Tai Po Sewage Treatment Works – Stage V (No. AEIAR-081/2004) (TPSTW EIA)

l   Trunk Road T2 (No. AEIAR-174/2013) (T2 EIA)

l   Central Kowloon Route (No. AEIAR-171/2013) (CKR EIA)

6.2                       Water Quality Objectives

6.2.1                 The WPCO provides the statutory framework for the protection and control of water quality in Hong Kong. According to the ordinance and its subsidiary legislation, Hong Kong waters are divided into ten Water Control Zones (WCZs). Corresponding statements of Water Quality Objectives (WQOs) are stipulated for different water regimes (marine waters, inland waters, bathing beaches, secondary contact recreation subzones and fish culture subzones) based on their beneficial uses. The WQOs for WCZ-VH are shown in Table 6-1.

Table 6-1      Summary of Water Quality Objectives for Victoria Harbour WCZ

Parameters

Objectives

Sub-Zone

Offensive Odour, Tints

Not to be present

Whole zone

Visible foam, oil scum, litter

Not to be present

Whole zone

Dissolved Oxygen (DO) within 2 m of the seabed

Not less than 2.0 mg/L for 90% of samples

Marine waters

Depth-averaged (DA) DO

Not less than 4.0 mg/L for 90% of samples

Marine waters

pH

To be in the range of 6.5 – 8.5, change due to human activity not to exceed 0.2

Marine waters

Salinity

Change due to human activity not to exceed 10% of ambient

Whole zone

Temperature

Change due to human activity not to exceed 2°C

Whole zone

Suspended solids (SS)

Not to raise the ambient level by 30% caused by human activity

Marine waters

Unionised Ammonia (UIA)

Annual mean not to exceed 0.021 mg/L as unionized form

Whole zone

Nutrients

Shall not cause excessive algal growth

Marine waters

Total Inorganic Nitrogen (TIN)

Annual mean depth-averaged inorganic nitrogen not to exceed 0.4 mg/L

Marine waters

Toxic substances

Should not attain such levels as to produce significant toxic, carcinogenic, mutagenic or teratogenic effects in humans, fish or any other aquatic organisms.

Whole zone

Human activity should not cause a risk to any beneficial use of the aquatic environment.

Whole zone

Source:    Statement of Water Quality Objectives (Victoria Harbour (Phase One, Two and Three) Water Control Zone.).

 

6.2.2                 The HKPSG, Chapter 9 (Environment), provides additional guidelines against water pollution for sensitive uses such as aquaculture and fisheries zones, bathing waters and other contact recreational waters. At present, there is no contact recreational water activities in the study area.

6.2.3                 Besides the WQOs set under the WPCO, WSD have also specified a set of water quality criteria for flushing water at seawater intakes shown in Table 6-2.

Table 6-2     WSD’s Water Quality Criteria for Flushing Water at Sea Water Intakes

Parameter

(in mg/L unless otherwise stated)

Target Limit

Colour (HU)

< 20

Turbidity (NTU)

< 10

Threshold Odour Number (odour unit)

< 100

Ammonia Nitrogen (NH3-N)

< 1

Suspended Solids (SS)

< 10

Dissolved Oxygen (DO)

> 2

5-day Biochemical Oxygen Demand (BOD5)

< 10

Synthetic Detergents

< 5

E. coli (no./100 mL)

< 20,000

 

6.2.4                 Based on Comprehensive Feasibility Study for Wanchai Development Phase II (CFSWDII) EIA, a SS limit of 40 mg/L has been adopted as the assessment criterion for Admiralty Centre intake and MTRC South intake (Point 9 and Point 8 respectively in Figure 4.3). According to EMSD, there is no specific water quality requirements for the intake of the District Cooling System (DCS) at Kai Tak, and no information on the SS limit is available from other operating cooling water intakes. According to Territory-wide Implementation Study of Water-cooled Air Conditioning Systems in Hong Kong – Executive Summary to Strategic Environmental Assessment, the water quality of influent to the cooling system is not a major concern while the thermal effect and the quantities of residual chemicals and reaction by-products of the effluent is of concern. The effluent quality should have to be dealt with by the cooling system independently.

6.2.5                 Besides setting the WQOs, the WPCO controls effluent discharging into any WCZ through a licensing system. The TM-DSS issued under Section 21 of the WPCO, gives guidance on permissible effluent discharges based on the type of receiving waters (foul sewers, storm water drains, inland and coastal waters). The limits control the physical, chemical and microbial quality of effluent.

6.2.6                 A practice note for professional persons (ProPECC) was issued by the EPD to provide guidelines for handling and disposal of construction site discharges. The ProPECC PN1/94 “Construction Site Drainage” provides good practice guidelines for dealing with ten types of discharge from a construction site. These include surface runoff, groundwater, boring and drilling water, bentonite slurry, water for testing and sterilisation of water retaining structures and water pipes, wastewater from building construction, acid cleaning, etching and pickling wastewater from site facilities and should be followed as far as possible during construction to minimise the water quality impact due to construction site activities.

6.2.7                 Possible indirect impact on subtidal habitat may arise due to water quality deterioration. Hard corals are known to be at particular risk of deleterious impacts from sedimentation through smothering and clogging of their respiratory and feeding apparatus. Similarly, more turbid water may reduce the amount of light reaching beneath the water surface which may also be detrimental to hard corals. With less light, growth rates of hermatypic hard corals (the only type of coral to possess photosynthetic algae called zooanthellae) may be reduced. The effects of increased sediment levels in the water column also extend to other marine groups apart from the corals. For instance, fauna inhabiting soft substrata may also be smothered if sedimentation rates are very high.

6.2.8                 The WQO for suspended solids in the Victoria Harbour WCZ states that waste discharges shall not raise the ambient level by 30%. This was adopted in the TPSTW EIA Study as the criterion for assessing the SS impacts on corals in Victoria Harbour.

6.2.9                 Literature reviews indicate that lethal responses had not been reported in adult fish at a SS concentration of below 125 mg/L. The AFCD consultancy Study on Fisheries and Marine Ecological Criteria for Impact Assessment provides the guideline values for different parameters for protection of local marine fisheries resources. The guideline values for relevant parameters are given in Table 6-3 below.

Table 6-3     Assessment Criteria for Local Marine Biota and Fisheries Resources

Parameter

Continuous Concentration (mg/L)

Maximum Concentration (mg/L)

Minimum Concentration (mg/L)

Ammonia, at pH 8.0 (Total ammonia as NH3-N)

0.7

1.2

-

Dissolved Oxygen

5

-

2

Total Suspended Solids

Site Specific

50

-

6.3                       Description of Environment

6.3.1                 In 2006, the marked improvements in the eastern Victoria Harbour (VM1 and VM2) and moderate improvements in the mid harbour area (VM4 and VM5) since HATS Stage 1 was commissioned were generally sustained. Several monitoring stations in the WCZ are located close to sewage outfalls, including VM5 (Wan Chai East and Wan Chai West Preliminary Treatment Works (PTW) outfall), VM6 (Central PTW outfall), VM4 (North Point PTW outfall) and VM8 (Stonecutters Islands STW – HATS Stage 1 outfall), see Figure 6-3-1. The water quality at these stations was inevitably subject to the direct impact of sewage discharge from these outfalls.

6.3.2                 According to EPD released water quality monitoring data for Victoria Harbour in 2014, compliance with WQO for TIN in VM1, VM2 and VM4 are 92%, 78% and 81% of saturation respectively. The bottom average DO in VM1, VM2 and VM4 are 77%, 71% and 68% respectively and depth average DO in VM1, VM2 and VM4 are 78%, 76% and 73% respectively. The average E. coli count in VM1, VM2 and VM4 are 1454, 5672 and 6109 respectively.

6.3.3                 A summary of the published EPD monitoring data (in 2006) collected from the monitoring stations in the Kwun Tong Typhoon Shelter (KTTS) (VT4) and To Kwa Wan Typhoon Shelter (TKWTS) (VT11) is presented in Table 6-4. Marine water quality monitoring is conducted by EPD at the typhoon shelters on a monthly basis. Water samples are taken at three water depths, namely, 1 m below water surface, mid-depth and 1 m above sea bed, except where the water depth is less than 6 m, in which case the mid-depth station may be omitted. Locations of the monitoring stations are shown in Figure 6-3-1.

Table 6-4     Summary Statistics of 2006 Marine Water Quality at the Kwun Tong and To Kwa Wan Typhoon Shelter

Parameter

Kwun Tong

VT4

To Kwa Wan

VT11

WPCO WQO

(in marine waters)

Temperature

(°C)

23.9

(17.5 – 28.8)

23.5

(17.2 – 28.6)

Not more than 2°C in daily temperature range

Salinity

(ppt)

29.3

(23.2 – 31.4)

30.5

(21.8 – 32.7)

Not to cause more than 10% change

Dissolved Oxygen (DO) (% saturation)

Depth average

68

(29 – 112)

83

(56 – 115)

Not available

Bottom

66

(26 – 110)

84

(54 – 117)

Not available

Dissolved Oxygen (DO) (mg/l)

Depth average

4.9

(2.0 – 7.6)

6.0

(3.9 – 7.9)

Not less than 4 mg/L for 90% of the samples

Bottom

4.7

(1.8 – 7.4)

6.0

(3.7 – 8.0)

Not less than 2 mg/L for 90% of the samples

pH value

7.7

(7.4 – 8.1)

8.0

(7.7 – 8.3)

6.5 – 8.5 (±0.2 from natural range)

Secchi disc

(m)

1.4

(1.0 – 2.0)

1.7

(0.9 – 2.5)

Not available

Turbidity

(NTU)

12.7

(4.1 – 30.1)

14.8

(9.0 – 22.1)

Not available

Silica (as SiO2)

(mg/l)

1.0

(0.4 – 1.8)

0.7

(0.2 – 1.6)

Not available

Suspended Solids (SS)

(mg/l)

2.6

(1.2 – 3.5)

6.7

(2.4 – 20.6)

Not more than 30% increase

5-day Biochemical Oxygen Demand (BOD5) (mg/l)

2.2

(1.1 – 3.5)

1.0

(0.6 – 1.6)

Not available

Nitrite Nitrogen (NO2-N)

(mg/l)

0.157

(0.082 – 0.227)

0.029

(0.012 – 0.059)

Not available

Nitrate Nitrogen (NO3-N)

(mg/l)

0.34

(0.22 – 0.64)

0.16

(0.05 – 0.42)

Not available

Ammoniacal

Nitrogen (NH3-N)

(mg/l)

0.48

(0.29 – 0.65)

0.12

(0.06 – 0.21)

Not available

Unionised Ammonia (UIA)

(mg/l)

0.011

(0.005 – 0.016)

0.004

(0.002 – 0.006)

Not more than 0.021 mg/L for annual mean

Total Inorganic Nitrogen (TIN) (mg/l)

0.97

(0.71 – 1.42)

0.31

(0.13 – 0.54)

Not more than 0.4 mg/L for annual mean

Total Nitrogen (TN)

(mg/l)

1.33

(1.02 – 1.82)

0.53

(0.39 – 0.80)

Not available

Ortho-Phosphate (PO4)

(mg/l)

0.214

(0.153 – 0.295)

0.028

(0.007 – 0.050)

Not available

Total Phosphorus (TP)

(mg/l)

0.26

(0.20 – 0.36)

0.05

(0.04 – 0.06)

Not available

Chlorophyll-a

(μg L-1)

18.2

(1.0 – 35.0)

7.9

(1.0 – 20.5)

Not available

E. coli

(cfu per 100 mL)

9,200

(2,800 – 29,000)

1,100

(340 – 4,400)

Not available

Faecal Coliforms

(cfu per 100 mL)

22,000

(4,400 – 78,000)

2,600

(860 – 8,300)

Not available

Note:    1.           Except as specified, dated presented are depth-averaged data.

2.                   Data presented are annual arithmetic means except for E.coli and faecal coliforms that are geometric means.

3.                   Data enclosed in brackets indicate ranges.

 

6.3.4                 Due to the embayment form and reduced flushing capacity of the typhoon shelter, marine water within the typhoon shelter is vulnerable to pollution. According to KTD EIA, in 2006, high levels of E.coli were recorded at the KTTS and TKWTS indicating faecal contamination. A high level of total inorganic nitrogen (TIN) was also recorded at the KTTS which breached the WQO.

6.3.5                 According to T2 EIA, the existing water quality in the Study Area has been monitored for many years as part of the EPD’s routine monitoring programme. The EPD’s marine water quality monitoring stations within the Victoria Harbour WCZ include VM1, VM2 and VT4 (inside the Kwun Tong Typhoon Shelter), as shown in Figure 6-3-1. A summary of the EPD’s Routine Water Quality Data for these stations for the years 2010 and 2014 is given in Table 6-5 below.

6.3.6                 These monitoring results show that the water quality of Victoria Harbour, VM1 and VM2 and the of KTTS, VT4 in general meets the Water Quality Objectives for Victoria Harbour and WSD’s Water Quality Criteria for sea water intakes.

6.3.7                 At the time of drafting this report, it is noted that CEDD will adopt an Interceptive Pumping Scheme to replace the originally proposed 600 m opening located at the former airport runway. This will likely improve the flushing effect and the water quality of KTAC.

Table 6-5      Summary of EPD’s Routine Water Quality Data (VM1, VM2 and VT4) for Victoria Harbour WCZ (Kwun Tong Typhoon Shelter) (2010 and 2014)

Parameters

Monitoring Station

VM1

VM2

VT4

2010

2014

2010

2014

2010

2014

Temperature (°C)

22.8

(16.5-27.3)

22.4

(16.0-29.2)

23.0

(16.5-27.3)

22.9

(16.2-29.1)

23.8

(18.3-28.3)

23.6

(17.1 - 29.0)

Salinity (ppt)

32.0

(29.2-33.6)

32.4

(24.1-34.1)

31.7

(29.1-33.7)

31.8

(24.7-33.2)

29.4

(22.9-31.6)

29.7

(26.8 - 32.0)

Dissolved Oxygen (mg/L)

5.6

(3.3-7.6)

5.7

(2.1-8.3)

5.4

(3.5-6.7)

5.5

(1.2-8.1)

5.2

(2.1-7.5)

5.8

(4.5 - 6.4)

Bottom Dissolved Oxygen

(mg/L)

4.8

(1.1-6.3)

5.7

(2.1-8.2)

4.8

(1.2-6.4)

5.2

(1.2-8.1)

5.9

(2.6-8.4)

5.4

(2.8 - 7.0)

SS (mg/L)

4.0

(1.4-8.1)

4.3

(0.8-24)

3.6

(0.9-7.6)

3.0

(1.0-7.0)

5.0

(1.6-16.7)

3.0

(0.9 - 7.3)

BOD5 (mg/L)

0.7

(<0.1-1.2)

0.7

(<0.1-3.2)

0.9

(<0.1-1.6)

1.0

(0.1-3.2)

1.8

(1.5-2.6)

1.5

(0.4 - 2.6)

Unionised NH3

(mg/L)

0.003

(<0.001-0.010)

0.002

(<0.001-0.005)

0.004

(<0.001-0.011)

0.003

(<0.001-0.008)

0.011

(0.005-0.022)

0.007

(0.002 - 0.011)

TIN (mg/L)

0.20

(0.09-0.32)

0.20

(0.09-0.56)

0.27

(0.10-0.40)

0.28

(0.14-0.51)

1.03

(0.55-1.81)

2.00

(0.89 - 3.90)

Ortho-P (mg/L)

0.020

(0.010-0.036)

0.019

(0.005-0.043)

0.024

(0.011-0.039)

0.025

(0.006-0.05)

0.140

(0.080-0.186)

0.356

(0.183 - 0.703)

Total P (mg/L)

0.03

(0.02-0.06)

0.03

(0.02-0.06)

0.04

(0.02-0.05)

0.04

(0.02-0.07)

0.17

(0.10-0.22)

0.43

(0.24 - 0.87)

Chlorophyll-a (µg/L)

2.8

(0.5-12.2)

3.2

(<0.2-36)

3.3

(0.5-15.4)

3.7

(<0.2-21)

13.9

(1.0-26.7)

9.3

(1.1 - 20.3)

E. coli (cfu/100mL)

710

(180-4400)

520

(120-9700)

2000

(420-17000)

2700

(320-8600)

820

(330-6000)

1600

(150 - 33000)

Note:

1.       Data presented are depth averaged (except as specified) and are the annual arithmetic mean except for E.coli (geometric mean);

2.       Data in brackets indicate ranges;

3.       Underlined indicates occurrence of non-compliance with that parameter of WQO.

6.3.8                 As reported in the KTD EIA, water quality monitoring in Kai Tak Nullah (KTN), KTAC and KTTS were carried out since 2005/2006. Since then, CEDD have conducted regular water quality monitoring. According to unpublished water quality monitoring data of survey conducted in 2015, significant reduction in water pollutants, including BOD5 and E.coli in KTN compared with 2005/2006 data were observed after the successful implementation of dry weather flow interceptor (DWFI) since mid-2013. Comparison of the pollution loads between 2005/2006 survey adopted under the EIA Study for KTD approved in 2009 and the survey conducted in 2015 are shown in Table 6-6.

Table 6-6      Summary of Pollution Load Surveys in 2005/06 and 2015

Location

Survey Event (dry season1)

Flow

(m3/day)

BOD2

(kg/day)

E.coli3

(cfu/day)

KTN

2005/06

342,553

7,650

8.13E+15

2015

309,190

2,509

8.49E+14

Change

(10%

(67%

(90%

Note:    1.        Dry season refers to October to April.

2.             BOD denotes biochemical oxygen demand which is the amount of oxygen required for microbial metabolism of organic compounds in water. It reflects the quantity of organic wastes from expedient connections, unsewered areas and other non-point sources such as street washing being discharged into the drainage system.

3.             Escherichia coli (E.coli) is the most commonly used and internationally accepted indicator on bacterium in water pollution monitoring. The level of E.coli indicates the level of faecal contamination of a water body.

6.3.9                 Monitoring data on average dissolved oxygen1 (DO), as summarized in Table 6-7, indicates that the water quality at KTAC/KTTS has been substantially improved as reflected from the gradual increase in average DO level in general since 2012. Sampling locations are shown in Figure 6-3-2. This indicates that the water quality at KTAC and KTTS has been substantially improved for the past few years.

Table 6-7      Average DO Level at KTAC/KTTS (Unit: mg/l)

Year

KTAC

KTTS

AC1

AC2

AC3

AC4

AC5

AC6

AC7

KT1

2012

1.7

1.6

2.6

2.1

3.1

2.4

3.7

4.7

2013

2.5

2.7

3.0

3.6

3.5

4.1

4.5

5.7

2014

3.9

3.8

4.1

4.0

4.5

4.4

4.7

5.4

Note:    Quarterly monitoring data for 2012 and 2013. Weekly monitoring data for period starting from April 2014.

1    Dissolved Oxygen (DO) refers to the level of free, non-compound oxygen present in water. It is an important parameter in assessing water quality because of its influence on marine organisms. In general, a higher DO represents a better water quality of the water body.

6.4                       Water Quality Sensitive Receivers

6.4.1                 According to KTD EIA, the water quality sensitive receivers (WSR) in the Victoria Harbour and its adjacent waters include:

l   Kai Tak River / Nullah

l   WSD Flushing Water intakes

l   Cooling Water Intakes for Kai Tak District Cooling System (KTDCS)

l   Typhoon Shelters

l   Corals and

l   Fish and Culture Zones at nearby water control zone

The water monitoring stations in these water bodies are considered as WSRs.

It is noted that CEDD is carrying out Comprehensive Review on KTD EIA, and there will be changes in KTDCS and its water intakes, however, the review is not yet finalized according to CEDD. As reported in Section 6.3.7, CEDD will adopt an Interceptive Pumping Scheme to replace the originally proposed 600 m opening under the former Kai Tak Runway. The existing cooling water intake C29 will be relocated to C29A, and a proposed intake C30 is proposed in KTN as shown in Figure 6-4-1.

6.4.2                 These WSR is shown in Figure 6-4-1. All of these sensitive receivers except Kai Tak River/Nullah are outside the study area, though VT11 and KTDCS are within and in close proximity of TKWTS, and C29A and C30 lie within KTAC and KTN respectively.

6.4.3                 As discussed in Sections 6.3.8 and 6.3.9 above, the water quality of KTN and KTAC have been significantly improved and the sewage from MPSC will not be discharged into KTN and KTAC. It is unlikely that the Project will have any effect on the water quality in KTAC.

6.5                       Assessment Methodology

6.5.1                 The assessment includes both construction phase and operation phase impacts. The potential water quality impacts due to these phases of the Project will be identified based on the source and nature of effluent generated. Any potential impact, if any, will be assessed.

6.5.2                 The construction of the Project would be mainly land-based except for barging of construction material and construction waste. Barging will make use of existing barging facilities being operated by MTR Shatin to Central Link (SCL) Project. MTR informed that the Kai Tak Barging Points have sufficient capacity to handle spoil generated from Government projects, including MPSC. Therefore, the marine environment will not be disturbed as no new marine working platform or reclamation of barging point is required, provided that mitigation measures or good practices as stated in Section 6.7.1 are followed. It is reasonable to assume that the water quality impact associated with the Project would be caused by on-site construction activities, construction runoff and drainage discharge from the construction site, provided that no discharge is allowed during marine transportation except for permitted dumping. The potential impact from these construction activities was reviewed. Practical water pollution control measures or mitigation proposals would be recommended to ensure that any discharge into the harbour from construction would comply with the WPCO standard.

6.5.3                 Water quality impact on operation phase of the Project will also be land-based generated from surface runoff and sewage. As sewage generated from the operation will be discharged into the sewerage system that will be transferred to treatment under the Harbour Area Treatment Scheme (HATS). The potential water quality impact from the land-based operational activities will be reviewed. Practical water pollution control or mitigation proposals were recommended to ensure that any discharge into the harbour from the operational activities would comply with the WPCO standards.

6.6                       Identification of Water Quality Impacts

Construction Phase

6.6.1                 During construction phase, the marine water activities include marine transportation of construction material, prefabricated items and construction waste material. Other activities will be land based.

Marine Activities

6.6.2                 The marine activities would not impose any adverse water quality impact provided that:

l   all marine operations shall comply with the current environmental and safety standards, see Appendix 6A,

l   no discharge into the sea will be allowed during marine transportation,

l   any marine dumping will be subject to separate Marine Dumping Permit.

Land Based Construction Activities

6.6.3                 The construction of the Project Site will involve the following activities:

l   Surface runoff is a potential water quality impact. Prior to commencement of construction, an efficient temporary surface water drainage system shall be designed and constructed to divert surface runoff from upstream catchment away from the site, and surface runoff within the site shall be discharged to the public drainage system, via adequately designed sand/silt removal facilities (such as sand traps, silt traps and sediment basins)

l   The general construction works would be primarily land-based but would have the potential to cause water pollution. Various types of construction activities may generate wastewater. These include boring and other geotechnical operations which may involve pumping of groundwater, general cleaning and polishing, wheel washing, dust suppression and utility installation. These types of wastewater other than groundwater from dewatering would contain high concentrations of suspended solids. Impacts could also result from the accumulation of solid and liquid waste such as packaging and construction materials, and sewage effluent from the construction work force involved with the construction. If uncontrolled, these could lead to deterioration in water quality. Increased nutrient level from contaminated discharges could lead to a number of secondary water quality impacts including localised increase in ammonia and nitrogen concentrations that would stimulate algal growth.

l   During a rainstorm, site runoff generated would wash away the soil particles. The runoff is generally characterised by high concentrations of suspended solids. Release of uncontrolled site runoff would increase the SS levels and turbidity in the nearby water environment.

l   Windblown dust would be generated from exposed soil surface in the works areas. It is possible that windblown dust would fall directly onto the nearby water bodies when a strong wind occurs. Dispersion of dust within the works areas may increase the SS levels in surface runoff causing a potential impact to the nearby sensitive receivers.

6.6.4                 The potential water quality impacts during construction phase of the Project are evaluated as follows:

General Construction Activities

l   The effects on water quality from general construction activities are likely to be minimal, provided that site drainage would be well maintained and good construction practices would be observed to ensure that litter, fuels, and solvents are managed, stored and handled properly.

l   Based on the Sewerage Manual, Part I, 1995 of the Drainage Services Department (DSD), the sewage production rate for construction workers is estimated at 0.35 m3 per worker per day. For every 100 construction workers working simultaneously at the construction site, about 35 m3 of sewage would be generated per day. The sewage should not be allowed to discharge directly into the surrounding water body without treatment. Sufficient chemical toilets should be provided for workers. Temporary sewage tank can be provided by contractor to collect sewage from temporary site toilets and regular clearing of the sewage tank by outsourced contractor can be arranged.

Construction Runoff and Drainage

l   Construction runoff and drainage may cause local water quality impacts. Increase in SS arising from the construction site could block the drainage channels and may result in local flooding when heavy rainfall occurs. High concentrations of suspended degradable organic material in marine water could lead to reduction in DO levels in the water column.

l   It is important that proper site practice and good site management be followed to prevent runoff with high level of SS from entering the surrounding waters. With the implementation of appropriate measures to control runoff and drainage from the construction site, disturbance of water bodies would be avoided and deterioration in water quality would be minimal. Ground water pumped out of wells, etc for dewatering shall be discharged into storm drains after removal of silt in silt removal facilities. Thus, unacceptable impacts on the water quality are not expected, provided that the recommended measures described in Section 6.7.1 – 6.7.10 and ProPECC PN 1/94 in Appendix 6B are properly implemented.

Groundwater Seepage during Construction

l   There is no substantial earthwork carried out in MPSC site except bulk excavation for hotel basement which will be confined by sheet pile with sufficient penetration below excavation level to provide adequate seepage cut-off. Thus, groundwater contamination is very remote if contaminated groundwater is identified during construction and operation, such impact should be assessed, and also be reduced by mitigation measures discussed in Section 6.7.4 below.

l   De-contamination of this Site have been completed and no contaminated issues are envisaged. However, any discharge / recharge of groundwater generated from this area shall be controlled to avoid any groundwater contamination.

l   Most of the foundations are prebored steel H piles found on rock. Preboring will be carried out with temporary casing in soil strata while casing may not be used in rock strata. The fluid used in preboring will be fresh water and there is no groundwater contamination during foundation construction.

Operation Phase

6.6.5                 During operation of the Project, all discharged water will be separated into sewer and stormwater system. Rainwater harvesting system shall be adopted for the Project as far as practicable. Rainwater on the top roof which is considered as clean source will be directed to the rainwater harvesting storage tank by gravity. The treatment of harvested rainwater will consist of pre-treatment, filtration and disinfection system. The whole treatment process shall be in compliance with the requirements in Technical Specifications on Grey Water Reuse and Rainwater Harvesting issued by WSD. The use of recycled rainwater including but not be limited to irrigation for the planting area within MPSC site can be regarded as most appropriate usage of recycled rainwater in the development. Only the surface runoff from MPSC may cause water quality impact to the Victoria Harbour as all sewage will be transported to HATS. Any trade effluent discharge is controlled by WPCO and is regulated through WPCO discharge licence about which the wastewater quality should meet TM-DSS before discharging to the communal sewer and then to Stonecutters Island STW for treatment via To Kwa Wan Preliminary Treatment Works (TKWPTW). As explained in Section 7.5.4, the average dry weather flow from the Project is 0.046 m3/sec which is about 1.5% of the capacity of TKWPTW and it is insignificant in Stonecutters Island STW. The impact on TKWPTW and Stonecutters Island STW is insignificant.

6.6.6                 The potential water quality impacts during operation phase of the Project are evaluated as follows:

l   Normal operation of sports and leisure facilities will generate sewage from spectators which will be discussed in Chapter 7, surface runoff will be discharged to the stormwater drainage system subject to interception of contaminated water. Any contaminated surface water shall be mitigated as stated in Section 6.7.15. The stormwater runoff from MPSC will not induce additional flow to the stormwater system as the total runoff will not be increased because the original site is basically impervious. A new stormwater drainage system for MPSC will deliver the stormwater to KTN which is adequately designed and improved to serve Kai Tak Area and effluent from Tolo Harbour Effluent Export Scheme. For the MPSC site of 28.2 ha, peak discharge flow of 1 in 200 year storm based on a rainfall intensity of 100 mm/hr will be 7.8 m3/sec which is compatible to the Final DIA Report for MPSC (Nov 2009) of 7,500 l/sec, which would not impose hydrological impact to KTN and KTAC.

l   The total site coverage and gross floor area of the ancillary/supporting facilities including the hotel, office area for sports-related organization and commercial area are 6,700 m2 and 89,000 m2 respectively. They are normal commercial developments not of significant scale that would not impose water quality impact provided that separate sewerage and stormwater systems are properly designed for, with relevant oil interceptors provided.

l   The potential water quality impact would be caused by dripping of organics from vehicles in car parking area.

l   There will be some level of chemicals/fuels to be stored on site, such as cleaning products, turf maintenance products (fertilizers/pesticides etc.), different type of fuel. Most venues will limit the storage to small essential quantities at any one time and re-stock as necessary. They must be stored in specific and appropriate areas/containers/cabinets within bunded area. Therefore, the risk of accidental spillage is insignificant.

l   Routine general cleaning and focused cleaning before and after large scale functions; the potential impacts may be caused by use of detergents in cleaning seats and building facades, and mixing of solids with the stormwater runoff. However, it is not a usual practice as to apply cleansing detergents to cleanse the stadium seats. The general practice is to clean the stadium seats before and after an event or to hose down the washing only on needed basis without using cleansing detergents. Wash water will be either collected for recycling or drained according to the design of the stadium.

l   Repair maintenance and renovation works: the potential water quality impact would be caused by mixing of solids with stormwater runoff and possible discharge of liquefied petroleum products for renovation works.

l   The maintenance of the turf may involve the application of fertilizers and pesticides which may cause water pollution or groundwater contamination in the case when chemical fertilizers and insecticides are used.

The mitigation measures are discussed in Section 6.7 below.

 

6.7                       Mitigation Measures for Adverse Environmental Impacts

Construction Phase Impacts

Construction Site Runoff and General Construction Activities

6.7.1                 To minimize the potential water quality impacts from construction site runoff and various construction activities, the practices outlined in ProPECC PN 1/94 Construction Site Drainage should be adopted. A copy of the ProPECC PN 1/94 is given in Appendix 6B. It is recommended to install perimeter channels in the works areas to intercept runoff from boundary prior to the commencement of any earthwork. To prevent storm runoff from washing across exposed soil surfaces, intercepting channels should be provided. Drainage channels are also required to convey site runoff to sand/silt traps and oil interceptors. Provision of regular cleaning and maintenance can ensure the normal operation of these facilities throughout the construction period. Any practical options for the diversion and realignment of drainage should comply with both engineering and environmental requirements in order to ensure adequate hydraulic capacity of all drains. Minimum distances of 100 m should be maintained between the discharge points of construction site runoff and the existing WSD saltwater intake and EMSD cooling water intake. As no new barging point will be provided and the existing barging facilities being operated by MTR SCL Project will be used, the following good site practices should be continuously be adopted:

l   All vessels should be sized so that adequate clearance is maintained between vessels and the seabed in all tide conditions, to ensure that undue turbidity is not generated by turbulence from vessel movement or propeller wash.

l   All hopper barges should be fitted with tight fitting seals to their bottom openings to prevent leakage of material.

l   Construction activities should not cause foam, oil, grease, scum, litter or other objectionable matter to be present on the water within the site.

l   Loading of barges and hoppers should be controlled to prevent splashing of material into the surrounding water.

Barges or hoppers should not be filled to a level that will cause the overflow of materials or polluted water during loading or transportation.

6.7.2                 All wastewater arising from construction site is also subject to the control of WPCO, about which a discharge licence is normally required. However, in this project, all the runoff and wastewater generated from the works areas should be treated so that it satisfies all the standards listed in the TM-DSS. Reuse and recycling of the treated effluent can minimize water consumption and reduce the effluent discharge volume particularly when a concrete batching plant is installed within the site. The beneficial uses of the recycled water may include dust suppression, wheel washing and general cleaning. It is anticipated that the wastewater generated from the works areas would be of small quantity. The Contractor shall follow the effluent monitoring requirements in the discharge license. 

6.7.3                 The construction programme should be properly planned to minimize soil excavation, if any, in rainy seasons. This prevents soil erosion from exposed soil surfaces. Any exposed soil surfaces should also be properly protected to minimize dust emission. In areas where a large amount of exposed soils exist, earth bunds or sand bags should be provided. Exposed stockpiles should be covered with tarpaulin or impervious sheets at all times. The stockpiles of materials should be placed at locations away from any stream courses so as to avoid releasing materials into the water bodies. Final surfaces of earthworks should be compacted and protected by permanent work. It is suggested that haul roads should be paved with concrete and the temporary access roads protected using crushed stone or gravel, wherever practicable. Wheel washing facilities should be provided at all site exits to ensure that earth, mud and debris would not be carried out of the works areas by vehicles.

6.7.4                 Good site practices should be adopted to keep the site dry and tidy, such as clean the rubbish and litter on the construction sites so as to prevent the rubbish and litter from spreading from the site area, provide adequate temporary site drainage and pumping, if necessary, to keep the site dry so as to minimize or completely eliminate groundwater seepage. It is recommended to clean the construction sites on a regular basis.

Sewage from Workforce

6.7.5                 The presence of construction workers generates sewage. It is recommended to provide sufficient temporary toilets in the works areas. The toilet facilities should be more than 30 m from any watercourse. A licensed waste collector should be deployed to clean the temporary toilets on a regular basis.

6.7.6                 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. Regular environmental audit on the construction site can provide an effective control of any malpractices and can achieve continual improvement of environmental performance on site. It is anticipated that sewage generation during the construction phase of the Project would not cause water pollution problem after undertaking all required measures.

Accidental Spillage of Chemicals

6.7.7                 Contractor must register as a chemical waste producer if chemical wastes would be produced from the construction activities. The Waste Disposal Ordinance (Cap 354) and its subsidiary regulations in particular the Waste Disposal (Chemical Waste) (General) Regulation should be observed and complied with for control of chemical wastes.

6.7.8                 Any service shop and maintenance facilities should be located on hard standings within a bunded area, and sumps and oil interceptors should be provided. Maintenance of vehicles and equipment involving activities with potential for leakage and spillage should only be undertaken within the areas appropriately equipped to control these discharges.

6.7.9                 Relevant mitigation measures for construction phase as stated in Sections 6.7.1 – 6.7.8 shall apply to repair, maintenance and renovation works.

6.7.10             As explained in Section 6.6.6, the chemicals/fuels to be stores on site will be limited to small essential quantities at any one time. Any chemicals that may be carried away by water shall be contained in specific containers and cabinets under shelter and protected from weather. Any liquid chemical or fuel shall be contained in hard standing bunded area similar to those stated in Sections 6.7.7 – 6.7.9. The operator shall ensure that only staff trained in the use and handling the specific chemicals for specific tasks are allowed to handle the relevant chemicals. Therefore, the risk of chemical spillage is negligible.

Operational Phase

6.7.11             To minimise the potential water quality impacts from the Project, separate sewerage and stormwater system will be maintained properly. Oil interceptor in car parking area shall be designed and constructed according to Practice Note for Authorized Persons, Registered Structural Engineers and Registered Geotechnical Engineers, APP-46 (PNAP 124), copy included in Appendix 6B. All manholes, sand traps and oil interceptors shall be cleaned and maintained regularly.

6.7.12             Good practice should be adopted to clean the rubbish and litter on the sites so as to prevent rubbish and litter from spreading from the site area. It is recommended to clean the Project Site on a regular basis. Management guidelines shall be provided to the management team practically to separate and remove solids from discharging stormwater system.

6.7.13             As explained in Section 6.6.6, it is not a usual practice to apply cleansing detergents to cleanse stadium seats, no specific mitigation measures are required. As explained in Section 6.6.6, the chemical/fuels to be stored on site will be limited to small essential quantities at any one time. Any chemicals that may be carried away by water shall be contained in specific containers and cabinets under shelter and protected from weather. Any liquid chemical or fuel shall be contained in hard standing bounded area. The operator shall ensure that only staff that trained in the use and handling the specific chemicals for specific tasks are allowed to handle the relevant chemicals. Therefore, the risk of chemical spillage is negligible.

6.7.14             In the broad approach, mitigation measures to handle potential water quality impacts caused by residual fertilizers and pesticides may include any of the followings:

l   Use artificial turf as the default playing surface, subject to design and operation considerations, practically no mitigation measures are required. Natural turf may be occasionally overlaid during major events, e.g. the Rugby Sevens. The duration of the natural turf on the pitch should be minimized, and no pesticides and fertilizers should be used during the period under normal circumstances.

l   If natural turf is used as the default playing surface at the Main Stadium or the Public Sports Ground, the use and application of fertilizers and pesticides will follow normal practices in LCSD’s prevailing code of practice and the Pesticides Ordinance (Cap. 133). An intercepting system should be developed for storage of surface water for reuse and a Stormwater Re-use Management Plan should be prepared and implemented, so as to ensure no residual fertilizers and pesticides from the turf surface run-off is discharged.

l   Details of the intercepting system and the Stormwater Re-use Management Plan are discussed in the subsequent sections.

Option for water with residual fertilizers and pesticides

6.7.15             Mitigation measures to handle water with residual fertilizers and pesticides are discussed as follows:

l   Application of pesticides is neither part of daily routine nor a regular maintenance practice on turf management. It is important only when it is specifically against a particular pest or disease which happens only occasionally on seasonal basis or incident basis. The Leisure and Cultural Services Department (LCSD) has strict control on the use of chemicals according to the prevailing code of practice. The list of pesticides that can be used is based on the registered list of the Pesticide Registration and Control under Agriculture, Fisheries and Conservation Department (AFCD). The stadium management is very strict on the choice of chemicals and the application rate as over dosage of chemicals or their residual effect on the field will be harmful to the fine root system of the turf species and can impact on the appearance of the play field. Application of chemicals, if necessary, will be confined to the approved list and the dosage as well as the frequency and intensity should be well justified according to genuine operational needs. The LCSD has issued horticultural guidelines governing the use of chemicals on pests and disease control, safe use of pesticides as well as storage and handling, application. The subject guidelines have been enforced in all parks and gardens managed by the LCSD which includes the Hong Kong Stadium on turf management. The future management of the MPSC should follow Pesticide Ordinance (Cap 133), Pesticide Regulations (Cap 133A), A Guide to Labeling of Pesticides, and Safety Guidelines for Storage of Pesticides issued by AFCD and the LCSD horticultural guidelines on use of turf management and consult AFCD on pesticides used.

l   Fertilizers which are commonly used on turf maintenance are basically slow release. Excessive application or over concentration of fertilizers will burn up the fine root system of the turf species whereas quick release fertilizers will induce rapid runoff and mean wastage. As the fine root system of the turf species is very sensitive about the dosage and type of fertilizers, the application is therefore well controlled according to genuine operational need and should not be too frequent and over applied. Depending on actual needs, application will usually be done once biweekly.

l   In order to minimize water quality impact due to deposited pesticides and residual fertilizers on the turf, the dosage of pesticides and fertilizers shall be controlled to limit any residual dosage to less than 10%. Based on irrigation experience from Hong Kong Stadium, the water use for watering the pitch is about 40.5 m3 in wet season. It is reasonably conservative to assume that any residual fertilizers and washable deposited pesticides will be rinsed away through five cycles of watering, or equivalent raining. Therefore, the 250 m3 storage water tank is adequate to intercept most of the residual fertilizers and washable deposited pesticides. Volume estimation is included in Appendix 6C. In order to ensure a fail-safe system, a second standby tank of 250 m3 is provided to intercept any traces of residual fertilizer and washable deposited pesticides. The content in these two tanks will be recycled for irrigation. Under normal operation, the residual fertilizer and washable deposited pesticides are recycled through the first storage tank while any trace chemicals, if any, will also be recycled through the second storage tank. Practically, no residual fertilizer and washable deposited pesticides will be discharged to the stormwater system.

l   To cater for incidental rainstorms, a third holding tank of 250 m3 is provided so that the total capacity of these three tanks will be able to store rainwater collected from a Black Rainstorm Warning, i.e. 70 mm for one hour. Volume estimation is included in Appendix 6C. The Figure 6-7-1 shows the schematic diagram of the proposed system with three water storage/holding tanks.

l   According to Section 7.5.2(b) of Stormwater Drainage Manual, DSD (2013), the surface runoff coefficient, c, of flat grassland on sandy soil ranges from 0.05 to 0.15. Assuming c = 0.10, about 10% of the runoff will be discharged into the stormwater drains and about 90% of the surface water will be passed into the sand layer underneath the turf. Out of the 90% underground water, about 85% will be collected by porous drain and 5% are allowed to permeate into the underneath soil strata through a geotextile.

l   Thus, the 5% of surface runoff that permeates into ground will carry 0.5% of the chemicals. As shown on the Figure 6-7-2, about 13% of the percolated surface water from the Main Stadium will permeate to Victoria Harbour. According to available ground investigation information, the top 10mm soil strata in Kai Tak area are fill composed of compacted silty sand or silty coarse sand. Assuming permeability coefficient K = 10-5 m/sec, after Bowles (1988), see Table 6-8, the time for seepage water from the Main Stadium football pitch to reach Victoria Harbour is over 10 years. Thus, the 0.5% x 13% = 0.065% chemicals from the Main Stadium may have been absorbed or assimilated by microorganisms in the soil strata. There is practically no chance for the chemicals to reach Victoria Harbour through a natural sand filter of over 100 m long. The seepage flow and flow estimation based on Darcy’s Law is summarized in Figure 6-7-3. As shown in Figure 6-7-2, the seepage path from the Main Stadium to Victoria Harbour is the shortest, other seepage paths are too long to be considered. Similarly, the 5% of surface runoff that permeates into ground will carry 0.5% of the chemicals and most part of the seepage flow from the PSG is surrounded by buildings and Kai Tak Tunnel. Practically, the seepage from PSG will not reach Victoria Harbour or Kai Tak nullah. Furthermore, the PSG seepage is screened by tunnels and building foundation.

l   In order to ensure effective operation of the intercepting system, the storage tanks shall be emptied prior to application of fertilizers and pesticides. In general, the intercepted surface water may be recycled by irrigation into the football pitch.

l   With mitigation measures described in Section 6.7, no significant adverse impact during construction and operation is imposed on the water quality. As The Project Site is in close proximity to Victoria Harbour, which is a sensitive water control zone, the intercepting system is proposed as a precautionary measure to minimize water quality impact.

 

Table 6-8        Permeability Coefficient

100

10- 2

10- 5

10- 9

10- 11

 

 

 Clean gravel

   GW, GP

 

   Clean gravel and

sand mixtures

GW, GP

SW, SP

GM

 

 

Sand-silt

mixtures

SM, SL, SC

 

 

 Clays

 

Extract from Table 2-3 Foundation Analysis and Design Fourth Edition, Joseph E. Bowles (1988)

 

6.7.16             The system of collection and disposal of surface runoff is summarized in the Flow Chart as shown in Figure 6-7-4. In order to ensure a fail-safe system, a Stormwater Re-use Management Plan shall be prepared by the operator to ensure that no adverse water quality impact arising from the residual fertilizers and pesticides in the surface run-off from the turf. The proposed content of this Stormwater Re-use Management Plan is included in Appendix 6D. This Stormwater Re-use Management Plan shall include the following key elements:

l   Healthy use of fertilizers and pesticides, and safe operation of the chemical recycling and disposal.

l   Operation and maintenance of water storage/holding tanks.

l   Frequency of testing and sampling, and appropriate testing parameters of the residual fertilizer and washable deposited pesticides.

l   Action and Limit levels.

l   Emergency measures.

In order to encourage healthy use of fertilizers and pesticides, and safe operation of the chemical recycling and disposal, the Stormwater Re-use Management Plan is extended to control the application of fertilizer and pesticide with detailed operation control requirements of the intercepting system so that the application of fertilizer and pesticide are properly controlled and implemented in order to protect the Victoria Harbour WCZ. Time of application of fertilizer and pesticide is essential. Normally, application of fertilizer and pesticide during or right before heavy rainfall is prohibited. In addition, use of more specific, systemic and biodegradable pesticide in low dosage is more preferred. All these may form part of the integrated fertilizer and pesticide management programme to minimize the water quality impact.

6.8                       Cumulative Impacts

6.8.1                 The assessment of potential cumulative impacts due to related and possibly concurrent project activities and water pollution sources within the assessment area reveals no significant cumulative impact considering both marine based and land based related projects.

6.8.2                 The identified relevant water and marine based projects and land based projects are listed in Table 6-9.

Table 6-9                Relevant Marine Based and Land Based Projects Related to Water Quality

Project

Project Proponent

Construction Programme

Major Works

Central Kowloon Route (CKR)

Highways Department (HyD)

2017-2022

Temporary reclamation and dredging

Interception and Pumping Scheme

Civil Engineering and Development Department (CEDD)

2017-2020

Additional intake openings

Cross Bay Link (CBL)

CEDD

May 2017 to August 2018

Dredging and filling

Kai Tak River Improvement Works

DSD

2012-2018

Reconstruction and rehabilitation of KTN in stages from Po Kong Village Road to KTAC

KTD

CEDD

2013-2023

Comprehensive development of KT area covering about 328ha at To Kwa Wan, Ma Tau Kok, Kowloon Bay, Kwun Tong and Cha Kwo Ling. It also covers Kowloon Bay and Kwun Tong Typhoon Shelter

Shatin Central Link

MTRC

2010-2019

Tai Wai to Hung Hom section covering Kai Tak and To Kwa Wan Stations and tunnels between these stations.

6.9                       Residual Impacts

6.9.1                 Residual impacts are considered as net impact after practical implementation of mitigation measures of the proposed project considering the background environmental conditions, and impacts from other relevant, existing, committed and planned projects. As the sewage are transported to Stonecutters Island STW and any contaminated surface runoff are mitigated prior to discharge into the stormwater system, only qualitative assessment of residual impact during construction and operation of MPSC is carried out and quantitative assessment is considered not necessary.

6.9.2                 No significant adverse residual impact during construction and operation is envisaged provided that the mitigated measures described in Section 6.7 are implemented.

6.9.3                 The water quality residual impacts from MPSC are insignificant to public health, risk of life, local welfare and environmental resources of the concerned water body. With the implementation of mitigation measures, the residual contaminants in the surface runoff is expected to be insignificant, hence, it is unlikely to cause adverse water quality impact on the nearby water quality sensitive receivers.

6.10                   Conclusion

6.10.1             Potential water pollution sources from construction and operation of MPSC have been identified including construction runoff, sewage, possible contamination due to oil and grease, use of fertilizers, pesticides and waste construction materials. Sewage generated during construction and operation will be disposed off-site ultimately to Stonecutters Island STW. Other sources of polluted water will be intercepted for reuse and chemical waste is prohibited from discharging into stormwater system. It can be concluded that there is no significant water quality impact to the sensitive receivers provide that the mitigation measures are implemented during construction and operation phases.

6.10.2             As mitigation measures are required, regular site audit should be carried out to ensure the effectiveness of the mitigation measures.

6.11                   Recommendation

6.11.1             In the case when marine transportation is adopted during construction, all marine operations shall comply with the current environmental and safety standards, no discharge into the sea is allowed; and any marine dumping will be subjected to separate Marine Dumping Permit.

6.11.2             All land based construction shall follow ProPECC PN1/94.

6.11.3             The sewerage and stormwater system shall be designed and constructed to separate the sewage and uncontaminated surface runoff completely. Provisions shall be made to collect the contaminated surface runoff such as the use of interception and oil and petrol interceptor.

6.11.4             The Operator shall keep the Project Site in a well maintained and clean condition in order to avoid unexpected discharge of contaminated surface runoff into Victoria Harbour.

6.11.5             The operator shall ensure that cleansing detergents are not used for washing the spectator seats and shall encourage recycling the stormwater for irrigation or flushing use. In the case when natural turf is adopted in the MPSC, the operator shall consider using organic fertilizers and biological pesticides, and provide intercepting system and storage tanks to hold the contaminated surface water for recycling, irrigation or proper discharge if the water quality justifies. The operator shall prepare a Stormwater Re-use Management Plan that includes the management of fertilizers and pesticides following the Pesticide Ordinance, LCSD and AFCD guidelines, safe and proper use and handling of fertilizers and pesticides, the reuse of surface runoff and monitoring and audit requirements. As the management plan would include the use of fertilizers and pesticides, the operator shall consult AFCD and LCSD in preparation of the management plan. The management plan shall include the management and operation of the intercepting system, stating that the storage tanks should be emptied prior to application of pesticides and fertilizers.