Expansion of Hong Kong International Airport into a Three-Runway System

Baseline Water Quality Monitoring Report

December 2016

 

 

 

 

 

 

 

Contents

Executive Summary

1      Introduction

1.1    Background

1.2    Project Description

1.3    Purpose of this Report

1.4    Structure of the Report

2      Water Quality Monitoring

2.1    Monitoring Requirements

2.2    Monitoring Equipment and Methodology

2.3    Laboratory Measurement / Analysis

2.4    Monitoring Frequency and Duration

2.5    Monitoring Locations

2.6    Monitoring Parameters

3      Baseline Monitoring Results and Analysis

3.1    Baseline Water Quality Monitoring

3.2    Statistical Analysis of the Baseline Data

4      Event and Action Plan

4.1    Action and Limit Levels

4.2    Action and Limit Levels for Seawater Intakes

4.3    Event and Action Plan

5      Revisions to Updated EM&A Manual

6      Conclusion

 

 

Tables

Table 2.1:              Baseline Water Quality Monitoring Equipment 3

Table 2.2:              Laboratory Analysis for SS, Nutrient and Heavy Metals  4

Table 2.3:              Monitoring Locations for Baseline Water Quality Monitoring  5

Table 2.4:              Summary of Monitoring Stations and Parameters (May and July 2016) 6

Table 2.5:              Summary of Monitoring Stations and Parameters (August and September 2016) 7

Table 3.1:              Results of ANOVA Test (May and July 2016) 8

Table 3.2:              Refined Results of ANOVA Test (May and July 2016) 9

Table 3.3:              Refined ANOVA Test Results (August and September 2016) 10

Table 3.4:              Final Arrangement of Control and Impact Stations  10

Table 4.1:              Action and Limit Levels for General Impact Water Quality Monitoring and Regular DCM Monitoring  11

Table 4.2:              Action and Limit Levels for Intensive DCM Monitoring 12

Table 4.3:              Action and Limit Level for SR1 and SR8  13

Table 4‑4:              Event and Action Plan for General Impact Water Quality Monitoring  14

Table 5.1:              Recommended Revisions to Updated EM&A Manual 16

 

 

 

Figures

Figure 2.1 – Water Quality Monitoring Stations for Baseline Monitoring

Appendices

Appendix 1.1 – Construction Programme for Marine Works

Appendix 2.1 – Calibration Certificates

Appendix 3.1 – Baseline Water Quality Monitoring Results

Appendix 3.2 – Graphical Presentations of Baseline Water Quality Monitoring Results

 

Executive Summary

An Environmental Permit (Permit No.: EP-489/2014) for the construction and operation of the “Expansion of Hong Kong International Airport into a Three-Runway System” (the project) was granted by the Environmental Protection Department (EPD) on 7 November 2014.

Mott MacDonald Hong Kong Limited (MMHK) was commissioned by the Airport Authority Hong Kong (AAHK) to undertake the role of Environmental Team (ET) for carrying out the environmental monitoring and audit (EM&A) works of the project.

On 29 April 2016, AAHK received the Chief Executive-in-Council’s approval for draft Chek Lap Kok Outline Zoning Plan, as well as the authorization of the reclamation under the Foreshore and Sea-bed (Reclamations) Ordinance for the expansion of HKIA into a three-runway system.

A Baseline Water Quality Monitoring Report was prepared for submission before the commencement of marine construction works to fulfil Condition 3.4 of the EP.

The commencement of initial works was announced on 1 August 2016. A Baseline Water Quality Report which covers the baseline monitoring data collection in May and July 2016 was submitted to EPD.

While no marine construction works was undertaken during August and September 2016, general water quality monitoring was undertaken in these two months.  It was therefore proposed to adopt the water quality monitoring data collected in August and September 2016 to update the baseline water quality in order to further improve the baseline data to take into account potential variations within a year due to natural fluctuations of dissolved oxygen and also enhance the representativeness of other water quality monitoring parameters. For this, a Proposal for Review of Baseline Water Quality was submitted to and subsequently approved by EPD.

This Baseline Water Quality Monitoring Report presents all the water quality monitoring data obtained in May, July, August and September 2016.

Baseline Water Quality Monitoring

Baseline water quality monitoring was conducted three days per week, at mid-flood and mid ebb tides, at 23 water quality monitoring stations. Monitoring of DO, DO%, pH, temperature, turbidity, salinity and SS as well as current speed and direction were undertaken at all monitoring stations. For monitoring of DCM works, baseline monitoring of total alkalinity, heavy metals and nutrients were conducted at designated DCM-specific monitoring stations. As no marine construction works was conducted during the baseline water quality monitoring, the water quality monitoring results obtained are considered to be appropriate for adoption as the baseline water quality dataset for the 3RS project.

Action and Limit Levels

The Action and Limit levels for water quality impact monitoring have been set based on the 3RS baseline water quality monitoring conducted in May, July, August, and September 2016. The summary table of the Action and Limit levels for water quality are presented in Table I to Table III.

Table I:            Action and Limit Levels for General Impact Water Quality Monitoring and Regular DCM Monitoring

Parameters

Action Level

Limit Level

DO in mg/L

(Surface, Middle & Bottom)

Surface and Middle

4.5 mg/L

Surface and Middle

4.1 mg/L

5 mg/L for Fish Culture Zone (SR7) only

Bottom

3.4 mg/L

Bottom

2.7 mg/L

Suspended Solids (SS) in mg/L

23

or 120% of upstream control station at the same tide of the same day, whichever is higher

37

or 130% of upstream control station at the same tide of the same day, whichever is higher

Turbidity in NTU

22.6

36.1

Total Alkalinity in ppm

95

99

Representative Heavy Metals for early regular DCM monitoring

(Chromium and Nickel)

Same as for intensive DCM monitoring

Same as for intensive DCM monitoring

Representative Heavy Metals for regular DCM monitoring after completion of initial intensive DCM monitoring

(to be determined taking into account the findings of the initial intensive DCM monitoring)

Note:

1.     For DO measurement, non-compliance occurs when monitoring result is lower than the limits.

2.     For parameters other than DO, non-compliance of water quality results when monitoring results is higher than the limits.

3.     Depth-averaged results are used unless specified otherwise.

4.     The action and limit levels specified in this table does not apply to SR1A and SR8 (see Section 4.2).

5.     The action and limit levels for the two representative heavy metals chosen will be the same as that for the intensive DCM monitoring

Table II:           Action and Limit Levels for Intensive DCM Monitoring

Parameters

Action Level

Limit Level

Temperature in °C

 

1.8°C above the temperature recorded at representative control stations at the same tide of the same day

2°C above the temperature recorded at representative control stations at the same tide of the same day

Total Alkalinity in ppm

95

or 120% of upstream control station at the same tide of the same day, whichever is higher

99

or 130% of upstream control station at the same tide of the same day, whichever is higher

Nutrient (mg/l)

 

 

Ammonia (NH3)

0.18

0.20

Unionised ammonia (NH3)

(with 0.021 mg/L as the upper limit)

0.01

0.01

Nitrite (NO2)

0.12

0.13

Nitrate (NO3)

1.05

1.18

TKN

0.6

0.7

Total Phosphorus

0.06

0.07

Reactive Phosphorus

0.04

0.04

Heavy Metals (µg/l)

 

 

Cadmium (Cd)

0.1

0.1

Chromium (Cr)

0.2

0.2

Copper (Cu)

1.9

5.1

Nickel (Ni)

3.2

3.6

Lead (Pb)

0.2

0.2

Zinc (Zn)

6

8

Arsenic (As)

3

4

Silver (Ag)

0.1

0.1

Mercury (Hg)

0.05

0.05

Note:

1.     Non-compliance of water quality results when monitoring results is higher than the limits.

2.     Depth-averaged results are used unless specified otherwise.

3.     For Cd, Cr, Pb, Ag and Hg, the percentile values are below detection limit, hence the Action and Limit levels represent detection limit.

4.     Where the water quality results at control stations for individual parameters are below detection limit, the value of the detection limit will be adopted.

Table III:          Action and Limit Levels for SR1 and SR8

SS (mg/l)

Action Level

Limit Level

SR1

To be determined prior to its commissioning

To be determined prior to its commissioning

SR8

52

60

 

Should non-compliance of the water quality criteria occur, the Event and Action Plan as presented in Section 4.3 of this report (for general impact water quality monitoring) and in the Detailed Plan on Deep Cement Mixing (for DCM monitoring) shall be followed.

 

 


1        Introduction

1.1      Background

On 7 November 2014, the Environment Impact Assessment (EIA) Report (Register No.: AEIAR-185/2014) for the “Expansion of Hong Kong International Airport into a Three-Runway System” (the project) was approved and an Environmental Permit (EP) (Permit No.: EP-489/2014) was issued for the construction and operation of the project.

On 29 April 2016, AAHK received the Chief Executive-in-Council’s approval for draft Chek Lap Kok Outline Zoning Plan, as well as the authorization of the reclamation under the Foreshore and Sea-bed (Reclamations) Ordinance for the expansion of HKIA into a three-runway system.

Mott MacDonald Hong Kong Limited (MMHK) was commissioned by the Airport Authority Hong Kong (AAHK) to serve as the project’s Environmental Team (ET) for carrying out the environmental monitoring and audit (EM&A) works of the project.

A Baseline Water Quality Monitoring Report was prepared for submission before the commencement of marine construction works to fulfil Condition 3.4 of the EP.

The commencement of initial works was announced on 1 August 2016. A Baseline Water Quality Report which covers the baseline monitoring data collection from 3 to 14 May 2016 and from 19 to 30 July 2016 was submitted to EPD.

As stated in the Monthly Environmental Monitoring & Audit (EM&A) Report No. 8 (for August 2016) and Report No. 9 (for September 2016) submitted for the project, the key marine activities included mobilization and off-site plant fabrication for the DCM contracts, CLP cable diversion enabling works, site investigation works and site survey. No marine construction works was undertaken during August and September 2016. However, general water quality monitoring was undertaken in accordance with the requirements provided in the EM&A Manual for impact water quality monitoring for August and September 2016.  It was therefore proposed to adopt the water quality monitoring data collected in these two months to update the baseline water quality in order to further improve the baseline data to take into account potential variations within a year due to natural fluctuations of dissolved oxygen and also enhance the representativeness of other water quality monitoring parameters.  For this, a Proposal for Review of Baseline Water Quality was submitted to and subsequently approved by EPD. 

1.2      Project Description

The project covers the expansion of the existing airport into a three-runway system with key project components comprising land formation of about 650 ha and all associated facilities and infrastructure including taxiways, aprons, aircraft stands, a passenger concourse, an expanded Terminal 2, all related airside and landside works and associated ancillary and supporting facilities.  The existing submarine aviation fuel pipelines and submarine power cables also require diversion as part of the works.

The current construction programme for marine works is provided in Appendix 1.1 and it has been prepared based on the best available information. Given the scale and complexity of the project, the details of the programme as presented is subject to further revision and update.

1.3      Purpose of this Report

This Baseline Water Quality Monitoring Report presents all the water quality monitoring data obtained in May, July, August and September 2016. The baseline water quality monitoring has been undertaken based on the approach and methodology presented in the updated EM&A Manual.

1.4      Structure of the Report

The structure of the report is as follows:

    Section 1 Introduction – presents the project background, purpose and structure of this baseline water quality monitoring report;

    Section 2 Water Quality Monitoring Methodology – presents the monitoring requirements and methodology on baseline water quality monitoring;

    Section 3 Baseline Monitoring Results and Analysis – presents the baseline monitoring results and the findings of the statistical analysis;

    Section 4 Event and Action Plan – presents the action and limit levels as well as event and action plan for impact water quality monitoring.

 

2        Water Quality Monitoring

2.1      Monitoring Requirements

In accordance with the updated EM&A Manual, the baseline water quality monitoring was conducted to establish ambient conditions prior to the commencement of the marine works. The baseline conditions for water quality were established by measuring dissolved oxygen (DO), dissolved oxygen saturation (DO%), pH, temperature, turbidity, salinity, and suspended solids (SS) at all designated stationary monitoring stations before commencement of marine works for the project. To provide the baseline water quality for the DCM-specific monitoring, total alkalinity was measured at all the relevant stationary impact stations, plus nutrients and heavy metals at the “IM*” stations (which represent the contaminated mud pit locations) as presented in Section 2.5.

2.2      Monitoring Equipment and Methodology

Water samples for all monitoring parameters were collected, stored, preserved and analysed according to the Standard Methods, APHA 22nd ed. and/or other methods as agreed by the EPD. In-situ measurements at monitoring locations including temperature, pH, DO, turbidity, salinity and water depth were collected by equipment listed in the following Table 2.1. Water samples for nutrients, heavy metals and SS analysis were stored in high density polythene bottles with no preservative added, packed in ice (cooled to 4 şC without being frozen), delivered to the laboratory within 24 hours of collection.

Table 2.1:         Baseline Water Quality Monitoring Equipment

Equipment

Brand and Model

Quantity

Water Sampler

Van Dorn Water Sampler

4

Positioning Device (measurement of GPS)

Garmin eTrex Vista HCx

2

Water Depth Detector  (measurement of water depth)

Lowrance Mark 5x

2

Multifunctional Meter (measurement of DO, pH, temperature, salinity and turbidity)

YSI 6920

2

Current Meter (measurement of current speed and direction)

Sontek HydroSurveyor

2

Digital Titrator (measurement of total alkalinity)

Titrette Digital Burette 50ml Class A

2

 

Calibration of In-situ instruments

All in-situ monitoring instrument were checked, calibrated and certified by a laboratory accredited under HOKLAS before use. Responses of sensors and electrodes were checked with certified standard solutions before each use.

Wet bulb calibration for a DO meter was carried out before commencement of monitoring and after completion of all measurements each day. Calibration was not conducted at each monitoring location as daily calibration is adequate for the type of DO meter employed. A zero check in distilled water was performed with the turbidity probe at least once per monitoring day. The probe should then be calibrated with a solution of known NTU. In addition, the turbidity probe was calibrated at least twice per month to establish the relationship between turbidity readings (in NTU) and levels of suspended solids (in mg/L).  Accuracy check of the digital titrator was performed at least once per monitoring day.

Calibration certificates of the monitoring equipment used in the baseline monitoring are provided in Appendix 2.1.

2.3      Laboratory Measurement / Analysis

Analysis of SS, nutrients and heavy metals have been carried out by a HOKLAS accredited laboratory, ALS Technichem (HK) Pty Ltd (Reg. No. HOKLAS 066). Sufficient water samples were collected at all the monitoring stations for carrying out the laboratory SS, nutrients and heavy metals determination. The SS, nutrients and heavy metals determination works were started within 24 hours after collection of the water samples. The analysis of SS, nutrients and heavy metals have followed the standard methods summarised in Table 2.2.

Table 2.2:         Laboratory Analysis for SS, Nutrient and Heavy Metals

Parameters

Instrumentation

Analytical Method

Reporting Limit

Suspended Solid (SS)

Analytical Balance

APHA 2540D

2 mg/L

Nutrients

 

 

 

Ammonia as N

FIA

APHA 4500

0.01 mg/L

Unionised ammonia (NH3)*

By calculation

By calculation

By calculation

Nitrite as N

FIA

APHA 4500

0.01 mg/L

Nitrate as N

FIA

APHA 4500

0.01 mg/L

TKN as N

Titration

APHA 4500

0.1 mg/L

Total Phosphorus

Colorimetric

APHA 4500

0.01 mg/L

Reactive Phosphorus

FIA

APHA 4500

0.01 mg/L

Heavy Metals

 

 

 

Cadmium (Cd)

ICP-MS

USEPA 6020A

0.1 µg/L

Chromium (Cr)

ICP-MS

USEPA 6020A

0.2 µg/L

Copper (Cu)

ICP-MS

USEPA 6020A

0.2 µg/L

Nickel (Ni)

ICP-MS

USEPA 6020A

0.2 µg/L

Lead (Pb)

ICP-MS

USEPA 6020A

0.2 µg/L

Zinc (Zn)

ICP-MS

USEPA 6020A

1 µg/L

Arsenic (As)

ICP-MS

USEPA 6020A

1 µg/L

Silver (Ag)

ICP-MS

USEPA 6020A

0.1 µg/L

Mercury (Hg)

ICP-MS

APHA 7470A

0.05 µg/L

*Note:     Calculation based on the laboratory result of ammonia nitrogen (NH4-N) and in-situ measured pH, salinity and temperature.

2.4      Monitoring Frequency and Duration

To account for potential variations within a year, the baseline was conducted in May (from 3 to 14 May 2016), July (from 19 to 30 July 2016), August (from 4 to 30 August 2016) and September (from 1 to 29 September 2016).  

The baseline water quality monitoring was conducted three days per week, at mid-flood and mid-ebb tides, at 23 water quality monitoring stations. Samples were taken at three depths (at 1m below surface, at mid-depth, and at 1m above bottom) for locations with water depth >6m. For locations with water depth between 3m and 6m, water samples were taken at two depths (surface and bottom). For locations with water depth <3m, only the surface depth was taken. Duplicate water samples were taken and analysed.

2.5      Monitoring Locations

The baseline monitoring was conducted at a total of 23 water quality monitoring stations, comprising 12 impact stations, eight sensitive receiver stations and three control stations. The monitoring locations for baseline monitoring are shown in Table 2.3.

Alternative Monitoring Locations

Based on the provisions and requirements set out in Section 5.1.5 of the Updated EM&A Manual, changes in monitoring locations were proposed for SR1, SR4 and SR5. Agreement from the IEC and approval from the EPD were sought for the changes. The locations of the alternative monitoring stations, including SR1A, SR4A and SR5A, are shown in Figure 2.1. Table 2.3 summarises the updated coordinates of the alternative monitoring locations.

Temporary Alternative Monitoring Location for SR1

A temporary change of the monitoring location for SR1 was identified necessary as a silt curtain was installed at the waters blocking access to SR1. Therefore, the proposed temporary monitoring location (SR1A) is slightly shifted to around 159 m to the west of SR1. The temporary alternative monitoring station at SR1A is the closest accessible location to the future permanent SR1. Given the constraints identified, the change of location to SR1A is considered to be the best practicable and representative location for baseline water quality monitoring at this water sensitive receiver.

It should be noted that SR1/SR1A is used to represent the seawater intake for the future HKBCF, however, this seawater intake is not yet in operation and therefore the future permanent location for SR1 during impact monitoring is subject to finalisation after the HKBCF seawater intake is commissioned.

Permanent Alternative Monitoring Locations for SR4 and SR5

Changes of the monitoring locations for SR4 and SR5 were required as the water depths around the original monitoring locations at SR4 and SR5 were found to be too shallow (less than 1.5m). The alternative monitoring locations at SR4A and SR5A are outside the shallow waters, i.e., with sufficient water depths for access by the sampling vessel (with a draft of about 2.5m). The alternative monitoring locations are the closest and accessible locations to the bay areas of the two WSRs. Hence, they are considered to be practicable and representative locations for monitoring the construction phase water quality impact at the WSRs.

The final coordinates of the monitoring stations for baseline monitoring are shown in Table 2.3 and their locations are shown in Figure 2.1.

Table 2.3:         Monitoring Locations for Baseline Water Quality Monitoring

Monitoring Stations

 

Coordinates

 

Description

Easting

Northing

C1

Control

804247

815620

C2

Control

806945

825682

C3

Control

817803

822109

IM1

Impact

806458

818351

IM2

Impact

806193

818852

IM3

Impact

806019

819411

IM4

Impact

805039

819570

IM5

Impact

804924

820564

IM6

Impact

805828

821060

IM7

Impact

806835

821349

IM8

Impact

807838

821695

IM9*

Impact

808811

822094

IM10*

Impact

809838

822240

IM11*

Impact

810545

821501

IM12*

Impact

811519

821162

SR1A(1)

Future Hong Kong-Zhuhai-Macao Bridge Hong Kong Boundary Crossing Facilities (HKBCF) Seawater Intake for cooling

812586

820069

SR2

Planned marine park / hard corals at The Brothers / Tai Mo To

814166

821463

SR3

Sha Chau and Lung Kwu Chau Marine Park / fishing and spawning grounds in North Lantau

807571

822147

SR4A(1)

Sha Lo Wan

807810

817189

SR5A(1)

San Tau Beach SSSI

810696

816593

SR6

Tai Ho Bay, Near Tai Ho Stream SSSI

814663

817899

SR7

Ma Wan Fish Culture Zone (FCZ)

823742

823636

SR8

Seawater Intake for cooling at Hong Kong International Airport (East)

811593

820417

Notes:

* Denotes baseline monitoring stations and/or parameters for DCM-specific monitoring

(1) Alternative monitoring location

2.6      Monitoring Parameters

Monitoring of DO, DO%, pH, temperature, turbidity, salinity and SS as well as current speed and direction were undertaken at all monitoring stations. For monitoring of DCM works, baseline monitoring of total alkalinity, heavy metals and nutrients were conducted at designated DCM-specific monitoring stations.

The monitoring parameters in May and July 2016 as well as in August and September 2016 are summarised respectively in Table 2.4 and Table 2.5.

Table 2.4:         Summary of Monitoring Stations and Parameters (May and July 2016)

Monitoring Stations

Type

Parameters Monitored

C1, C2, C3

Control

DO, pH, Temperature, Salinity, Turbidity, SS

IM1, IM2, IM3, IM4, IM5, IM6, IM7, IM8

Impact

DO, pH, Temperature, Salinity, Turbidity, SS

Total Alkalinity

IM9, IM10, IM11, IM12

Impact

DO, pH, Temperature, Salinity, Turbidity, SS

Total Alkalinity, Heavy Metals, Nutrients

SR1A, SR2, SR3, SR4A, SR5A, SR6, SR7, SR8

Sensitive Receiver

DO, pH, Temperature, Salinity, Turbidity, SS

Table 2.5:         Summary of Monitoring Stations and Parameters (August and September 2016)

Monitoring Stations

Type

Parameters Monitored

C1, C2, C3, SR2*

Control

DO, pH, Temperature, Salinity, Turbidity, SS

Total Alkalinity, Chromium, Nickel

IM1, IM2, IM3, IM4, IM5, IM6, IM7, IM8, IM9, IM10, IM11, IM12

Impact

DO, pH, Temperature, Salinity, Turbidity, SS

Total Alkalinity, Chromium, Nickel

SR1A, SR3, SR4A, SR5A, SR6, SR7, SR8

Sensitive Receiver

DO, pH, Temperature, Salinity, Turbidity, SS

*Note:     SR2 replaces C3 as the flood tide control station (refer to Section 3.2 for details), and monitoring of total alkalinity, chromium and nickel commenced at SR2 starting in September 2016.

 

3        Baseline Monitoring Results and Analysis

3.1      Baseline Water Quality Monitoring

Detailed baseline water quality monitoring results in May, July, August and September 2016 are tabulated and presented in Appendix 3.1. Graphical presentations of the baseline monitoring results are provided in Appendix 3.2.

General weather conditions throughout the baseline water quality monitoring period were recorded. The collected data are presented in Appendix 3.1. The weather conditions were mainly fine and cloudy, and the sea conditions were mainly moderate throughout the baseline monitoring period.  

As no marine construction works was conducted during the baseline water quality monitoring, the water quality monitoring results obtained are considered to be appropriate for adoption as the baseline water quality dataset for the project.

3.2      Statistical Analysis of the Baseline Data

To analyse if there is any significant difference between control and impact stations, statistical analysis was conducted to compare the findings from the control station versus those from the impact / sensitive receiver stations. During baseline monitoring, DO, DO%, pH, temperature, salinity, turbidity and SS were monitored at the control stations, however, only turbidity and SS are linked to control station results during impact monitoring with respect to Action and Limit levels. As such, the statistical analysis was conducted for turbidity and SS only.

Statistical Analysis of Data Collected in May and July 2016

In the submission to EPD which covers the baseline monitoring data collected in May and July 2016 (see Section 1.1), statistical analysis of the collected data using one-way analysis of variance (ANOVA) was conducted. Impact stations were grouped according to corresponding control stations under flood tide and ebb tide conditions. The results of the ANOVA test are presented in Table 3.1.

Table 3.1:         Results of ANOVA Test (May and July 2016)

ANOVA Test Groups

P-value (alpha = 0.05)

Control Station

Impact Stations

SS

Turbidity

Flood Tide

 

 

 

C1

IM1, IM2, IM3, IM4, IM5, IM6, IM7, IM8, SR3

0.02

0.16

C3

IM7, IM8, IM9, IM10, IM11, IM12, SR1A, SR2, SR3, SR4A, SR5A, SR6, SR8

0.08

0.01

Ebb Tide

 

 

 

C1

SR4A, SR5A, SR6

0.42

0.87

C2

IM1, IM2, IM3, IM4, IM5, IM6, IM7, IM8, IM9, IM10, IM11, IM12, SR1A, SR2, SR3, SR7, SR8

0.11

0.73

Note:  bold values show statistically significant difference between control and impact stations

As shown in Table 3.1, significant difference is identified between C1 and its corresponding impact stations for SS during flood tide, and between C3 and its corresponding impact stations for turbidity during flood tide. No significant difference was identified for the other combinations, hence only the significant differences affecting C1 and C3 during flood tide were further evaluated.

At C1, the depth-averaged SS results during flood tide range from 5 to 43 mg/l, while those of the impact stations range from 3 to 40 mg/l. On average, the SS results at C1 are higher than the impact stations, due primarily to the presence of several high SS results at C1. If the highest and lowest C1 results are excluded from the ANOVA test, then the resulting P-value would be 0.07 (no significant difference). This suggests that the significant difference identified in Table 3.1 is a result of the extreme values rather than reflecting the majority of the C1 results. Extreme values can arise due to natural fluctuations in the marine environment, and given that in the absence of these extremes, the C1 results would show no significant difference with the impact stations, it is considered that overall, this control station is acceptable and representative for the purpose of impact monitoring.

At C3, the depth-averaged turbidity results during flood tide range from 3.2 to 12.6 mg/l, while those of the impact stations range from 3.9 to 51.7 mg/l. The results at C3 are significantly lower than the majority of the impact station results, suggesting that the location of C3 is unable to adequately represent the water quality at the impact stations under baseline conditions during flood tide. In this case, an alternative control station location to cover flood tide (for corresponding impact stations as shown in Table 3.1) is required. As shown in Figure 2.1, both C3 and SR2 are located upstream of the project during flood tides, and SR2 is located >2.7 km away from the marine works area of the project, hence is similar to C3 in that it is unaffected by marine works of the project during flood tide conditions. As SR2 is unaffected by the project during flood tide, it can effectively act as a control station during flood tide conditions. An ANOVA test using SR2 as control against the impact group (IM7, IM8, IM9, IM10, IM11, IM12, SR1A, SR3, SR4A, SR5A, SR6, SR8) was conducted and the resulting P-values are 0.58 and 0.89 for turbidity and SS respectively, which show that there is no significant difference.  Hence, the SR2 location is able to represent the water quality at these impact stations during flood tide under baseline conditions.

The refined ANOVA test results are summarised in Table 3.2.

Table 3.2:         Refined Results of ANOVA Test (May and July 2016)

ANOVA Test Groups

P-value (alpha = 0.05)

Control Station

Impact Stations

SS

Turbidity

Flood Tide

 

 

 

C1

IM1, IM2, IM3, IM4, IM5, IM6, IM7, IM8, SR3

0.07*

0.16

SR2

IM7, IM8, IM9, IM10, IM11, IM12, SR1A, SR3, SR4A, SR5A, SR6, SR8

0.89

0.58

Ebb Tide

 

 

 

C1

SR4A, SR5A, SR6

0.42

0.87

C2

IM1, IM2, IM3, IM4, IM5, IM6, IM7, IM8, IM9, IM10, IM11, IM12, SR1A, SR2, SR3, SR7, SR8

0.11

0.73

Note:  (*) excludes the highest and lowest values for SS at C1 during flood tide.

 

Statistical Analysis of Data Collected in August and September 2016

Statistical analysis using the same approach as mentioned above was conducted for the water quality monitoring data collected in August and September 2016.  The refined ANOVA test results are presented in Table 3.3.

Table 3.3:         Refined ANOVA Test Results (August and September 2016)

ANOVA Test Groups

P-value (alpha = 0.05)

Control Station

Impact Stations

SS

Turbidity

Flood Tide

 

 

 

C1

IM1, IM2, IM3, IM4, IM5, IM6, IM7, IM8, SR3

0.08*

0.13*

SR2

IM7, IM8, IM9, IM10, IM11, IM12, SR1A, SR3, SR4A, SR5A, SR6, SR8

0.38

0.08

Ebb Tide

 

 

 

C1

SR4A, SR5A, SR6

0.54

0.64

C2

IM1, IM2, IM3, IM4, IM5, IM6, IM7, IM8, IM9, IM10, IM11, IM12, SR1A, SR2, SR3, SR7, SR8

0.46

0.83

Note:  (*) excludes the highest and lowest values for SS and turbidity at C1 during flood tide.

As shown in Table 3.3, there is no significant difference between the control and impact stations.

Summary

In view of the aforementioned ANOVA test results, the final arrangement for the control and impact station groups under flood and ebb tide conditions are presented in Table 3.4.

Table 3.4:         Final Arrangement of Control and Impact Stations

Control Station

Impact Stations

Flood Tide

 

C1

IM1, IM2, IM3, IM4, IM5, IM6, IM7, IM8, SR3

SR2

IM7, IM8, IM9, IM10, IM11, IM12, SR1A, SR3, SR4A, SR5A, SR6, SR8

Ebb Tide

 

C1

SR4A, SR5A, SR6

C2

IM1, IM2, IM3, IM4, IM5, IM6, IM7, IM8, IM9, IM10, IM11, IM12, SR1A, SR2, SR3, SR7, SR8

 

 

 

4        Event and Action Plan

4.1      Action and Limit Levels

The baseline water quality monitoring data collected in May, July, August and September 2016 was used to determine the Action and Limit levels, using the derivation criteria specified in the updated EM&A Manual.

The presence of any outliers was checked, whereby the range of depth-averaged data (except for dissolved oxygen which separates surface and middle level data from bottom level data) are compared and those that do not conform to the dataset range as a whole are removed. Using this approach, two notably high depth-averaged results for suspended solids were identified as outliers (as shown in Appendix 3.1 and Appendix 3.2), and have been removed from the dataset used to determine Action and Limit levels.

Table 4.1:         Action and Limit Levels for General Impact Water Quality Monitoring and Regular DCM Monitoring

Parameters

Action Level

Limit Level

DO in mg/L

(Surface, Middle & Bottom)

Surface and Middle

4.5 mg/L

Surface and Middle

4.1 mg/L

5 mg/L for Fish Culture Zone (SR7) only

Bottom

3.4 mg/L

Bottom

2.7 mg/L

Suspended Solids (SS) in mg/L

23

or 120% of upstream control station at the same tide of the same day, whichever is higher

37

or 130% of upstream control station at the same tide of the same day, whichever is higher

Turbidity in NTU

22.6

36.1

Total Alkalinity in ppm

95

99

Representative Heavy Metals for early regular DCM monitoring

(Chromium and Nickel)

Same as for intensive DCM monitoring

Same as for intensive DCM monitoring

Representative Heavy Metals for regular DCM monitoring after completion of initial intensive DCM monitoring

(to be determined taking into account the findings of the initial intensive DCM monitoring)

Note:

1.     For DO measurement, non-compliance occurs when monitoring result is lower than the limits.

2.     For parameters other than DO, non-compliance of water quality results when monitoring results is higher than the limits.

3.     Depth-averaged results are used unless specified otherwise.

4.     The action and limit levels specified in this table does not apply to SR1A and SR8 (see Section 4.2).

5.     Details of selection criteria for the two heavy metals for early regular DCM monitoring refer to the Detailed Plan on Deep Cement Mixing available on the dedicated 3RS website http://env.threerunwaysystem.com/en/ep-submissions.html)

6.     The action and limit levels for the two representative heavy metals chosen will be the same as that for the intensive DCM monitoring

For intensive DCM monitoring, the Action and Limit levels to be adopted at the intensive DCM monitoring stations are presented in Table 4.2.

Table 4.2:         Action and Limit Levels for Intensive DCM Monitoring

Parameters

Action Level

Limit Level

Temperature in °C

 

1.8°C above the temperature recorded at representative control stations at the same tide of the same day

2°C above the temperature recorded at representative control stations at the same tide of the same day

Total Alkalinity in ppm

95

or 120% of upstream control station at the same tide of the same day, whichever is higher

99

or 130% of upstream control station at the same tide of the same day, whichever is higher

Nutrient (mg/l)

 

 

Ammonia (NH3)

0.18

0.20

Unionised ammonia (NH3)

(with 0.021 mg/L as the upper limit)

0.01

0.01

Nitrite (NO2)

0.12

0.13

Nitrate (NO3)

1.05

1.18

TKN

0.6

0.7

Total Phosphorus

0.06

0.07

Reactive Phosphorus

0.04

0.04

Heavy Metals (µg/l)

 

 

Cadmium (Cd)

0.1

0.1

Chromium (Cr)

0.2

0.2

Copper (Cu)

1.9

5.1

Nickel (Ni)

3.2

3.6

Lead (Pb)

0.2

0.2

Zinc (Zn)

6

8

Arsenic (As)

3

4

Silver (Ag)

0.1

0.1

Mercury (Hg)

0.05

0.05

Note:

1.     Non-compliance of water quality results when monitoring results is higher than the limits.

2.     Depth-averaged results are used unless specified otherwise.

3.     For Cd, Cr, Pb, Ag and Hg, the percentile values are below detection limit, hence the Action and Limit levels represent detection limit.

4.     Where the water quality results at control stations for individual parameters are below detection limit, the value of the detection limit will be adopted.

4.2      Action and Limit Levels for Seawater Intakes

According to the updated EM&A Manual, sensitive receiver stations representing seawater intakes for cooling are affected by SS only, and hence only the Action and Limit levels for SS parameter would be applicable. The Action and Limit levels at these intakes would be determined and agreed with the respective operators of the intakes prior to commencement of construction activities or commencement of operation of the seawater intake (whichever is later).

For the 3RS project, the status of the two seawater intakes for cooling (i.e. SR1 and SR8) at the time of preparation of this report are summarised below:

SR1 – to be constructed / commissioned. Programme of commissioning has been delayed (compared to original programme assumed at the time of approval of 3RS EIA report). Based on latest information from the project proponent of HKBCF, the earliest commissioning date for this intake is mid-2017. Operational tolerance for SS is subject to further liaison with the project proponent of HKBCF.

SR8 – in operation by AAHK. Appropriate Action and Limit levels have been proposed taking into account the operational tolerance of the intake and agreed with the operator and IEC.

The Action and Limit levels to be adopted for these seawater intakes are summarised in Table 4.3.

Table 4.3:         Action and Limit Level for SR1 and SR8

SS (mg/l)

Action Level

Limit Level

SR1

To be determined prior to its commissioning

To be determined prior to its commissioning

SR8

52

60

 

For SR1, the Action and Limit levels to be adopted are subject to further liaison and agreement with the project proponent of HKBCF. Meanwhile, it is recognised that SR1 is yet to be commissioned, hence it is not yet an existing sensitive receiver and consequently, would not be impacted by the 3RS project before it is commissioned. Given these circumstances, there is no need for conducting impact monitoring at this SR1 location prior to its commissioning date.

Separately, the future permanent monitoring location of SR1 is subject to further confirmation once the exact location of SR1 is determined, taking into account the need for silt curtains to be deployed around this SR1 location as part of the mitigation measures for 3RS project.

Given the aforementioned issues and programme mismatch, the final details for SR1 including its monitoring location, commissioning date and Action and Limit levels will be submitted to EPD prior to commissioning of the seawater intake at SR1 and documented in the monthly EM&A Report.

For SR8, it is noted that silt curtains are to be deployed around this SR8 location as part of the mitigation measures for 3RS project, while the intake itself is located within the works boundary of the 3RS project and will need to be relocated during construction phase. As such, the impact monitoring location for SR8 will be subject to further changes. Where the monitoring location needs to be updated, the updated location shall be notified to IEC and EPD and documented in the monthly EM&A Report.

4.3      Event and Action Plan

For general impact water quality monitoring, should non-compliance of the water quality criteria occur, the Event and Action Plan as presented in Table 4‑4 shall be followed. For DCM monitoring, the Event and Action Plan shall follow the Detailed Plan on Deep Cement Mixing, which can be accessed from http://env.threerunwaysystem.com/en/ep-submissions.html. The Event and Action Plan for the initial intensive DCM monitoring presented in the Detailed Plan on Deep Cement Mixing submitted under EP condition 2.17 shall be followed during the initial intensive DCM monitoring stage.

Table 4‑4:         Event and Action Plan for General Impact Water Quality Monitoring

 

Action

Event

ET

IEC

AAHK / PM

Contractor

Action level being exceeded by one sampling day

1. Repeat in-situ measurement to confirm findings;

2. Identify reasons for non-compliance and sources of impact;

3. Inform IEC and Contractor;

4. Check monitoring data, all plant, equipment and Contractor’s working methods;

5. Discuss mitigation measures with IEC and Contractor;

6. Repeat in-situ monitoring on the day after the exceedance.

1. Discuss with ET and Contractor on the mitigation measures;

2. Review proposals on mitigation measures submitted by Contractor and advise AAHK / PM accordingly;

3. Assess the effectiveness of the implemented mitigation measures.

1. Discuss with IEC on the proposed mitigation measures;

2. Make agreement on the mitigation measures to be implemented;

3. Assess the effectiveness of the implemented mitigation measures.

1. Inform AAHK / PM and confirm receipt of ET’s notification of the non-compliance in writing;

2. Rectify unacceptable practice;

3. Check all plant and equipment;

4. Provide report of the status and condition of plant, equipment and mitigation measures to ET

5. Consider changes of working methods;

6. Discuss with ET and IEC and propose mitigation measures.

Action Level being exceeded by more than two consecutive sampling days

1. Repeat in-situ measurement to confirm findings;

2. Identify reasons for non-compliance and sources of impact;

3. Inform IEC and Contractor;

4. Check monitoring data, all plant, equipment and Contractor’s working methods;

5. Discuss mitigation measures with IEC and Contractor;

6. Ensure mitigation measures are implemented;

7. Repeat in-situ monitoring on the day after the exceedance and prepare to increase the monitoring frequency to daily.

1. Discuss with ET and Contractor on the mitigation measures;

2. Review proposals on mitigation measures submitted by Contractor and advise AAHK / PM accordingly;

3. Assess the effectiveness of the implemented mitigation measures.

1. Discuss with IEC on the proposed mitigation measures;

2. Make agreement on the mitigation measures to be implemented;

3. Assess the effectiveness of the implemented mitigation measures.

1. Inform AAHK / PM and confirm receipt of ET’s notification of the non-compliance in writing;

2. Rectify unacceptable practice;

3. Check all plant and equipment;

4. Provide report of the status and condition of plant, equipment and mitigation measures to ET

5. Consider changes of working methods;

6. Discuss with ET and IEC and propose mitigation measures to IEC and AAHK / PM within three  working days;

7. Implement the agreed mitigation measures.

 

Limit Level being exceeded by one sampling day

1. Repeat in-situ measurement to confirm findings;

2. Identify reasons for non-compliance and sources of impact;

3. Inform IEC, Contractor and EPD;

4. Check monitoring data, all plant, equipment and Contractor’s working methods;

5. Discuss mitigation measures with IEC, AAHK / PM and Contractor;

6. Ensure mitigation measures are implemented;

7. Repeat in-situ monitoring on the day after the exceedance and prepare to increase the monitoring frequency to daily

1. Discuss with ET and Contractor on the mitigation measures;

2. Review proposals on mitigation measures submitted by Contractor and advise AAHK / PM accordingly;

3. Assess the effectiveness of the implemented mitigation measures.

1. Discuss with IEC, ET and Contractor on the proposed mitigation measures;

2. Request Contractor to critically review the working methods;

3. Make agreement on the mitigation measures to be implemented;

4. Assess the effectiveness of the implemented mitigation measures.

1. Inform AAHK / PM and confirm receipt of ET’s notification of the non-compliance in writing;

2. Rectify unacceptable practice;

3. Check all plant and equipment;

4. Provide report of the status and condition of plant, equipment and mitigation measures to ET

5. Consider changes of working methods;

6. Discuss with ET, IEC and AAHK / PM and propose mitigation measures to IEC and AAHK / PM within three working days;

7. Implement the agreed mitigation measures.

Limit Level being exceeded by more than one consecutive sampling days

1. Repeat in-situ measurement to confirm findings;

2. Identify reasons for non-compliance and sources of impact;

3. Inform IEC, Contractor and EPD;

4. Check monitoring data, all plant, equipment and Contractor’s working methods;

5. Discuss mitigation measures with IEC, AAHK / PM and Contractor;

6. Ensure mitigation measures are implemented;

7. Increase the in-situ monitoring frequency to daily until no exceedance of limit level for two consecutive days.

1. Discuss with ET and Contractor on the mitigation measures;

2. Review proposals on mitigation measures submitted by Contractor and advise AAHK / PM accordingly;

3. Assess the effectiveness of the implemented mitigation measures.

1. Discuss with IEC, ET and Contractor on the proposed mitigation measures;

2. Request contractor to critically review the working methods;

3. Make agreement on the mitigation measures to be implemented;

4. Assess the effectiveness of the implemented mitigation measures;

5. Consider and instruct, if necessary, the Contractor to slow down or to stop all or part of the construction activities until no exceedance of limit level.

1. Inform AAHK / PM and confirm receipt of ET’s notification of the non-compliance in writing;

2. Rectify unacceptable practice;

3. Check all plant and equipment;

4. Provide daily report of the status and condition of plant, equipment and mitigation measures to ET until no further exceedance;

5. Consider changes of working methods;

6. Discuss with ET, IEC and AAHK / PM and propose mitigation measures to IEC and AAHK / PM within three working days;

7. Implement the agreed mitigation measures;

8. As directed by AAHK / PM, to slow down or to stop all or part of the construction activities.

Note:  Where the action level is the same as the limit level, the actions specified for limit level exceedances shall apply.

 

5        Revisions to Updated EM&A Manual

As part of the baseline water quality monitoring conducted for the 3RS project and its subsequent findings and recommendations, the following revisions to the Updated EM&A Manual are recommended.

Table 5.1:         Recommended Revisions to Updated EM&A Manual

Relevant Section in Updated EM&A Manual

Original Requirement

Revisions Recommended

Section 5.1.3.14

Wet bulb calibration for a DO meter should be carried out before measurement at each monitoring location

Wet bulb calibration for a DO meter should be carried out before commencement of monitoring and after completion of all measurements each day

Table 5-2

Water Quality Monitoring Stations (construction and post construction phases)

Location of SR1 subject to finalisation after the HKBCF seawater intake is commissioned. The final location shall be documented in the monthly EM&A Report

As SR1 is yet to be commissioned, no impact monitoring will be conducted at SR1 prior to its commissioning date. The final commissioning date, once determined, shall be documented in the monthly EM&A Report

Alternative locations for SR4 and SR5 according to Table 2-3 of this Baseline Report

Table 5-4

Event and Action Plan for Water Quality

Supplementary and updated actions in the Event and Action Plan for Water Quality as per Table 4-4 of this Baseline Report

 

Aside from the revisions specified in Table 5.1, other revisions to the Updated EM&A Manual (e.g. due to other related 3RS submissions such as the Detailed Plan on Deep Cement Mixing) may also apply.

 

6        Conclusion

Baseline water quality monitoring was undertaken in May, July, August and September 2016 in accordance with the requirements set out in the EP and the updated EM&A Manual. All monitoring equipment used were properly calibrated and valid calibration certificates are included in this report.

To improve the baseline data to take into account potential variations within a year due to natural fluctuations of dissolved oxygen and also enhance the representativeness of other water quality monitoring parameters, the combined water quality data collected in May, July, August and September 2016 was adopted as the baseline dataset. The baseline water quality monitoring was carried out for three days per week at mid-flood and mid ebb tides, at a total of 23 water quality monitoring stations. The weather conditions were mainly fine and cloudy, and the sea conditions were mainly moderate throughout the baseline monitoring period. The results of baseline monitoring were provided in tables and graphical presentations in this report. As no marine construction works was conducted during the baseline water quality monitoring, the baseline water quality monitoring results obtained are considered to be appropriate for adoption as the baseline water quality dataset for the 3RS project. Where applicable, revisions to the Updated EM&A Manual are recommended.