Environmental Team for Hung Shui Kiu/Ha Tsuen New Development Area Stage 1 Works

Table A1	Summary of Baseline 1-hour TSP Monitoring Results
Table A2	Calculated Action and Limit Levels for 1-hour TSP
Table A3	Summary of Baseline Water Quality Monitoring Results
Table A4	Derived Action and Limit Levels for Water Quality
Table 2.1	Baseline Air Quality Monitoring Equipment
Table 2.2	Baseline Air Quality Monitoring Parameters, Frequency and Duration
Table 2.3	Original Air Quality Monitoring Stations for Baseline and Impact Monitoring
Table 2.4	Updated Air Quality Monitoring Stations for Baseline and Impact Monitoring
Table 2.5	Photo of Baseline Air Quality Monitoring Stations
Table 2.6	Summary of Baseline 1-hour TSP Monitoring Results
Table 2.7	Action and Limit Levels for Air Quality during Construction Period
Table 2.8	Calculated Action and Limit Levels for 1-hour TSP
Table 3.1	Parameters measured in the Baseline Water Quality Monitoring
Table 3.2	Original Baseline Water Quality Monitoring Stations
Table 3.3	Updated Location of Baseline Water Quality Monitoring Stations
Table 3.4	Baseline Water Quality Monitoring Equipment
Table 3.5	Detection Limits and Precision for Water Quality Determinates
Table 3.6	Analytical Methods Applied to Water Quality Samples
Table 3.7	Summary of Baseline Water Quality Monitoring Results
Table 3.8	Determination of Action and Limit Levels of Water Quality for Impact Monitoring
Table 3.9	Derived Action and Limit Levels for Water Quality

List of Figures

Figure 2.1	Air Quality Monitoring Locations
Figure 2.2	Baseline Air Quality Monitoring Schedule
Figure 3.1	Locations of Baseline Water Quality Monitoring Stations
Figure 3.2	Baseline Water Quality Monitoring Schedule

List of Appendices

Appendix A	Air Quality and Water Quality Monitoring Equipment Calibration Certificates
Appendix B	Baseline Air Quality Monitoring Results and Graphical Presentation
Appendix C	Baseline Water Quality Monitoring Data and Graphical Presentation
Appendix D	Quality Control Report for Suspended Solids
Appendix E	Event and Action Plan
Appendix F	HOKLAS Laboratory Certificate
Appendix G	Extract of Meteorological Observations for Hong Kong Lau Fau Shan

EXECUTIVE SUMMARY

In accordance with the Updated Environmental Monitoring and Audit Manual (April 2022) for the Project, baseline environmental monitoring for air quality and water quality should be conducted prior to the commencement of construction works of the interim section of Road D1. Pursuant to EP Condition 3.3, Baseline Monitoring Report shall be submitted to the Director of Environmental Protection at least 2 weeks before the commencement of construction of the Project. As the construction works would commence by end of 2022, baseline monitoring for air quality and water quality were conducted according to the Updated Environmental Monitoring and Audit Manual (April 2022) before the commencement of construction works.

The baseline monitoring for 1-hour TSP monitoring was carried out between 9 December 2021 and 22 December 2021 at three air quality monitoring stations. Baseline 1-hour TSP monitoring was conducted at least three times per day at each monitoring station when the highest dust impact was expected. Data collected were reviewed and analyzed to establish the background air quality at three monitoring stations. Table A1 summarizes the results of the baseline 1-hour TSP monitoring.

Table A1 Summary of Baseline 1-hour TSP Monitoring Results

Stations	Average (µg/m3)	Range (µg/m3)	Sampling Parameter
AM23	62.1	51.0 71.0	1-hour TSP
AM24	61.5	51.0 70.0
AM25a(1)	77.2	62.0 98.0

NOTE:

(1) The air quality monitoring station AM25 is currently located at an open/ storage area that is deemed not suitable for setting up air quality monitoring station. An alternative monitoring station AM25a next to San Wai Sewage Treatment Plant is proposed and approved by the IEC and the EPD.

The baseline 1-hour TSP monitoring results form the basis for determining the air quality criteria for the impact monitoring. Table A2 presents the Action and Limit Levels for impact monitoring of 1-hour TSP.

Table A2 Calculated Action and Limit Levels for 1-hour TSP

Monitoring Stations	Action Level (µg/m3)	Limit Level (µg/m3)
AM23	290.4	500
AM24	290.0
AM25a	300.2

Baseline water quality monitoring was also carried out at six water quality monitoring stations. Data collected were reviewed and analyzed to establish the background water quality at these six monitoring stations. Table A3 summarizes the results of the baseline water quality monitoring.

Table A3 Summary of Baseline Water Quality Monitoring Results

Locations		Parameters
Locations		Temperature (°C)	pH	Dissolved Oxygen (DO) (mg/L) (Middle)	Turbidity (NTU)	Suspended Solids (SS) (mg/L)
U1	Avg.	22.6	8.1	7.3	17.5	12.8
	Min.	19.9	7.3	4.3	4.7	3.7
	Max.	26.8	9.1	10.5	53.2	36.0
U2	Avg.	22.7	7.9	7.1	8.3	5.4
	Min.	20.3	7.3	3.4	2.5	1.3
	Max.	26.3	8.6	10.7	24.3	16.0
SW	Avg.	22.7	7.9	7.2	11.5	6.2
	Min.	20.2	7.4	3.5	1.9	<1.0
	Max.	26.4	8.6	10.7	23.2	24.0
HT	Avg.	22.6	8.0	6.9	16.2	15.4
	Min.	20.2	7.3	2.2	2.8	<1.0
	Max.	26.1	8.7	10.6	45.1	69.0
TKW1	Avg.	22.7	8.0	7.7	14.3	9.4
	Min.	20.3	7.4	2.8	3.4	<1.0
	Max.	26.4	8.7	10.8	63.2	54.0
TKW	Avg.	22.7	7.9	7.0	14.4	10.2
	Min.	20.2	7.4	2.4	4.0	<1.0
	Max.	26.3	8.7	10.3	57.3	52.0

The Action and Limit Levels for impact monitoring of water quality are presented in Table A4. They were derived based on the criteria specified in the Updated EM&A Manual.

Table A4 Derived Action and Limit Levels for Water Quality

Parameters	Action Levels	Limit Levels
SW
DO (mg/L) (3)	3.7	3.5
Turbidity (NTU)	21.4	22.9
SS (mg/L)	9.7	9.9
pH	Less than 6.6 or greater than 8.4	Less than 6.5 or greater than 8.5
HT
DO (mg/L) (3)	2.4	2.2
Turbidity (NTU)	32.3	32.6
SS (mg/L)	34.0	38.7
pH	Less than 6.6 or greater than 8.4	Less than 6.5 or greater than 8.5
TKW1
DO (mg/L) (3)	2.8	2.8
Turbidity (NTU)	27.9	29.2
SS (mg/L)	16.0	18.4
pH	Less than 6.6 or greater than 8.4	Less than 6.5 or greater than 8.5
TKW
DO (mg/L) (3)	2.5	2.4
Turbidity (NTU)	24.2	24.6
SS (mg/L)	19.8	21.6
pH	Less than 6.6 or greater than 8.4	Less than 6.5 or greater than 8.5

Notes:

(1) For DO, non-compliance of the water quality limit occurs when monitoring result is lower than the limit.

(2) For Turbidity and Suspended Solids (SS), non-compliance of the water quality limit occurs when monitoring result is higher than the limit.

(3) The derived Action Levels and Limit Levels for dissolved oxygen only apply to mid-depth.

1 INTRODUCTION 1.1 Project Background 1.1.1 The HSK/HT NDA occupies an area of approximately 714 ha and is located in the north-western part of the New Territories, midway between Tuen Mun and Tin Shui Wai New Towns. It is bounded by Tin Ying Road/ Ping Ha Road/ Kiu Hung Road to the east, Castle Peak Road to the south, Kong Sham Western Highway (KSWH) to the west, and Tin Ha Road, Lau Fau Shan Road and hillslopes along Deep Bay Road to the north. In the wider context, the proposed Project is strategically located in close proximity to Shenzhen, particularly Shenzhen Bay Control Point, Qianhai, and Shekou and efficiently linked with the Greater Pearl River Delta (PRD) region. The KSWH and the possible highway connecting the Project area with the Tuen Mun - Chek Lap Kok Link, the Hong Kong International Airport, Kwai Tsing Container Terminals, and the Hong Kong-Zhuhai-Macao Bridge and its Boundary Crossing facilities. New strategic highway infrastructure connecting the Project area with the urban area will also be planned to address the long-term development needs of North West New Territories (NWNT). The proposed West Rail Hung Shui Kiu Station (HSK Station), with its alignment traversing the Project allows convenient and efficient access to and from the Project area. 1.1.2 The works under HSK/HT NDA Stage 1 works comprises the construction of interim section of new distributor road (Road D1) (hereinafter call the Project) that is a designated project (DP) (defined under item A1 in Schedule 2 of the Environmental Impact Assessment Ordinance) connecting the site for the first batch of multi-storey buildings (MSBs) at Sites 3-6, 3-7 and 3-8 to the existing Ha Tsuen Roundabout of KSWH. 1.1.3 The HSK/HT NDA Stage 1 works would be implemented under a fast track programme, involving various complex tasks for providing infrastructure and forming the five development sites to be conducted in parallel, so as to tie in with operation of the development MSBs or other land-efficient means and population intake of the village resite house in 2025 tentatively. 1.1.4 The scope of works covered by Public Works Programme (PWP) Item No. 7796CL comprise the followings:

(i) Site formation works for Site 2-18, Site 2-19, Site 3-6, Site 3-7 and Site 3-8;

(ii) Land decontamination works including ground investigation works for Site 2-18, Site 2-19, Site 3-6, Site 3-7 and Site 3-8 and other areas within the boundaries of the site;

(iii) Construction of a district distributor road connecting to the existing interchange underneath KSWH, construction of local roads, widening of a section of Fung Kong Tsuen Road and associated junction/ road improvements; and

(iv) Engineering infrastructure works comprising sewerage works (including a pumping station), drainage works (including a detention pond), waterworks and landscaping works.

1.1.5 Acuity Sustainability Consulting Limited (ASCL) is commissioned by Civil Engineering and Development Department (CEDD) to undertake the Environmental Team (ET) services as required and/or implied, both explicitly and implicitly, in the Environmental Permit (EP), Environmental Impact Assessment (EIA) Report (Register No. AEIAR-203/2016) and Environmental Monitoring and Audit (EM&A) Manual for the Project; and to carry out the EM&A programme in fulfillment of the EIA Reports, EM&A requirements under Service Contract No. WD/02/2021. 1.1.6 Pursuant to the Environmental Impact Assessment Ordinance (EIAO), the Director of Environmental Protection Department (EPD) granted the Environmental Permits (Nos.: EP-526/2017, EP-527/2017, EP-528/2017, EP-529/2017, EP-530/2017 and EP-531/2017) to the CEDD for the Project. The HSK/HT NDA Stage 1 works comprise the interim section of Road D1 that is governed under Environmental Permit No. EP-528/2017. No other DPs are identified within the scope of HSK/HT NDA Stage 1 works. 1.2 Purpose of the Report 1.2.1 According to Appendix A of the Updated EM&A Manual for the Project, baseline monitoring for air quality and water quality should be conducted prior to the commencement of construction works. No designated noise monitoring stations are located with the 300 m buffer zone of the interim section of Road D1. As such, baseline (and construction phase) noise monitoring for Road D1 (interim section) is not recommended. 1.2.2 The EM&A requirements for baseline monitoring under Contract No. YL/2020/03 are set out in the Updated EM&A Manual (April 2022) and Contract Specification. Environmental aspect of air quality and water quality were identified as the key issues requiring implementation of monitoring programme during the construction phase of the Project. 1.2.3 This report presents the monitoring methodology, findings and results for the baseline air quality and water quality monitoring of the Project. According to the Updated EM&A Manual (April 2022), baseline landscape and visual monitoring should also be conducted. The results are reported in a separate standalone Baseline Landscape and Visual Monitoring Report. 1.3 Report Structure 1.3.1 This Baseline Monitoring Report comprises the following sections:

Section 1 introduces the background of the Project and purpose of this Report;

Section 2 presents the baseline monitoring methodologies, requirements, results, influencing factors, as well as determination of the action and limit levels of air quality;

Section 3 presents the baseline monitoring methodologies, requirements, results, influencing factors, as well as determination of the action and limit levels of water quality; and

Section 4 concludes the findings of baseline monitoring.

2 AIR QUALITY 2.1 Monitoring Requirement 2.1.1 Baseline air quality monitoring shall be carried out to determine the ambient 1-hour Total Suspended Particulates (TSP) levels at designated monitoring stations for 14 consecutive days prior to the commissioning of the construction works. 1-hour TSP monitoring should be carried out at least three times per day at each monitoring station when the highest dust impact are expected. 2.2 Monitoring Equipment and Methodology 2.2.1 Direct reading dust meters were used for measuring 1-hour TSP levels during the baseline air quality monitoring. According to paragraph 4.3.5 of the Updated EM&A Manual, the proposed use of direct reading dust meter was submitted to and agreed by the IEC. 2.2.2 The direct reading dust meters have been calibrated against high volume samples (HVSs) annually. A 2-day, three 3-hour measurement results per day from direct reading dust meters were taken to compare with the sampling results from the HVSs. The correlation between the direct reading dust meters and the HVSs were then concluded. By accounting for the correlation factor, the direct reading dust meters are considered to achieve comparable results as that of the HVSs. 2.2.3 Sufficient number of monitoring instruments were prepared by the ET for carrying out the baseline monitoring. All equipment and associated instrumentation were clearly labelled. 2.2.4 Equipment used in the baseline air quality monitoring programme is summarized in Table 2.1. Calibration certificates for the air quality monitoring equipment are attached in Appendix A.

Table 2.1 Baseline Air Quality Monitoring Equipment

Equipment	Brand and Model	Serial No.
Direct Reading Dust Meter	Aerocet 831	A14259
	Sibata LD-5R	851816
		851820
		992818

2.3 Monitoring Parameters, Frequency and Duration 2.3.1 Table 2.2 summarizes the monitoring parameters, frequency and duration of the baseline air quality monitoring.

Table 2.2 Baseline Air Quality Monitoring Parameters, Frequency and Duration

Parameters	Duration	Frequency
1-hour TSP	Daily for at least 14 consecutive days	3 times per day

2.4 Monitoring Location 2.4.1 According to the environmental findings detailed in the EIA report, the designated locations for the air quality monitoring are listed in Table 2.3.

Table 2.3 Original Air Quality Monitoring Stations for Baseline and Impact Monitoring

Station(s)	EIA ID	Monitoring Location
AM23	P1032	Planned Port Back-up, Storage and Workshop (at Site 3-6)
AM24	P1501	Planned Port Back-up, Storage and Workshop (at Site 3-8)
AM25	P606	Planned Port Back-up, Storage and Workshop (at Site 3-14)

2.4.2 The air quality monitoring station AM25 is currently located within an open area for parking of heavy goods vehicles. It is considered not safe and not suitable to set up the monitoring station within the open area. Hence, it is proposed to relocate AM25 to AM25a next to Sai Wan Sewage Treatment Plant (Figure 2.1) about 100 m south-southwest from AM25. The alternative monitoring stations of AM25a meets the following criteria as stated in Section 4.5.4 of the Updated EM&A Manual.

(i) At location close to the major dust emission source;

(ii) Close to the (planned) air sensitive receivers as defined in the EIAO-TM;

(iii) Proper position/ sitting and orientation of the monitoring equipment; and

(iv) Take into account the prevailing meteorological conditions (the prevailing meteorological conditions at AM25 and AM25a will be very similar as they are located at a flat land without barriers and around 100 m away from each other).

2.4.3 The Proposal for Alternative Monitoring Station (Air Quality) for monitoring station AM25a has been verified by the IEC and endorsed by the EPD. The updated locations for air quality monitoring are listed in Table 2.4.

Table 2.4 Updated Air Quality Monitoring Stations for Baseline and Impact Monitoring

Station(s)	EIA ID	Monitoring Location
AM23	P1032	Planned Port Back-up, Storage and Workshop (at Site 3-6)
AM24	P1501	Planned Port Back-up, Storage and Workshop (at Site 3-8)
AM25a	-	San Wai Sewage Treatment Plant near the Planned Port Back-up, Storage and Workshop (at Site 3-14)

2.4.4 The locations of all original air quality monitoring stations and the alternative air quality monitoring stations are shown in Figure 2.1. Photos of baseline air quality monitoring stations are presented in Table 2.5.

Table 2.5 Photos of Baseline Air Quality Monitoring Stations

ID	Direct reading dust meter Position	Monitoring direction
AM23
AM24
AM25a

3 WATER QUALITY 3.1 Monitoring Requirements 3.1.1 In accordance with the recommendations of the EIA Report (EIAO Register No. AEIAR-203/2016) and the Updated EM&A Manual (April 2022), the baseline water quality monitoring was conducted to establish baseline conditions prior to the commencement of the construction works. The baseline conditions for water quality were established to derive the Action and Limit levels for impact stations. 3.2 Water Quality Parameters and Monitoring Frequency 3.2.1 The parameters that have been selected for measurement in-situ and in the laboratory are those that are either determined in the EIA to be those with the most potential to be affected by the construction works or a standard check on water quality conditions. Parameters to be measured in the baseline water quality monitoring are listed in Table 3.1.

Table 3.1 Parameters measured in the Baseline Water Quality Monitoring

Parameters	Units	Abbreviations	Frequency
In-situ measurements			3 days per week for at least 4 weeks (the interval between 2 sets of monitoring should not be less than 36 hours)
Dissolved oxygen	mg/L	DO
Dissolved oxygen saturation	%	DO%
Temperature	oC	-
pH	-	-
Turbidity	NTU	-
Laboratory measurements
Suspended Solids	mg/L	SS

3.2.2 In addition to the water quality parameters, other relevant data were also being measured and recorded in data record sheet, including the location of the sampling stations, time, weather conditions, special phenomena and work activities undertaken around the monitoring stations and works area that may influence the monitoring results. 3.3 Monitoring Locations 3.3.1 The baseline water quality monitoring stations in accordance with the Updated EM&A Manual are shown in Figure 3.1 and detailed in Table 3.2 below.

Table 3.2 Original Baseline Water Quality Monitoring Stations

Station	Description	Easting	Northing
U1	Upstream Station	815936	834150
U2	Upstream Station	816240	834009
SW	Gradient station (downstream of U1 and the construction site of Road D1)	816304	834321
HT	Gradient station (downstream of U2 and the construction site of Road D1)	816866	834314
DB	Gradient station	816091	834976

3.3.2 During the site visit in November 2021, water quality monitoring station DB was surrounded by scrubs and vegetation. It is located at a natural stream channel running along the steep slope of the hill to the south-west of Fung Kong Tsuen. The watercourse runs towards the north of Road D1 but, based on the information from the governments GeoInfo Map and the site visit, no downstream watercourse was identified. Thus, water quality monitoring station DB is not recommended for this Contract without upstream/ downstream monitoring locations identified. 3.3.3 A new water quality monitoring station TKW was proposed at an open manmade channel downstream of Road D1 near Tseung Kong Wai and is within the 500 m assessment area of Road D1. Another monitoring location TKW1 about 20 m upstream of TKW at an open channel was also proposed (refer to Annex A of the Updated EM&A Manual for details). The Proposal has been verified by the IEC and endorsed by the EPD. The updated Baseline Water Quality Monitoring Stations are shown in Figure 3.1 and detailed in Table 3.3 below.

Table 3.3 Updated Locations of Baseline Water Quality Monitoring Stations

Station	Description	Easting	Northing
U1	Upstream Station	815936	834150
U2	Upstream Station	816240	834009
SW	Gradient station (downstream of U1 and the construction site of Road D1)	816304	834321
HT	Gradient station (downstream of U2 and the construction site of Road D1)	816866	834314
TKW1	Gradient station (downstream of the construction site of Road D1)	816563	834686
TKW	Gradient station (downstream of TKW1 and construction site of Road D1)	816594	834690

0002

Figure 3.1 Locations of Baseline Water Quality Monitoring Stations

3.4 Monitoring Equipment and Methodology 3.4.1 In-situ measurements at monitoring locations including DO, DO%, pH, temperature and turbidity were collected using the equipment listed in Table 3.4 and the detection limit for the in-situ measurement are shown in Table 3.5. Calibration certificates for the water quality monitoring equipment are attached in Appendix A. 3.4.2 Water samples for suspended solids (SS) analysis were stored in high density polythene bottles, packed in ice (cooled to 4 ºC without being frozen), and delivered to a HOKLAS laboratory as soon as possible after collection of the water samples.

Table 3.4 Baseline Water Quality Monitoring Equipment

Equipment	Brand and Model	Quantity
Water Sampler	Kahlsico Water Sampler 13SWB20	1
Multi Parameter Water Quality System	HORIBA U-53	2

Table 3.5 Detection Limits and Precision for Water Quality Determinates

Parameters	Detection limit	Accuracy	Precision
DO	0 20 mg/L	± 0.1 mg/L	25%
Temperature	0 45 oC	± 0.1 oC
pH	0 14	± 0.1
Turbidity	0 1000 NTU	± 2

3.4.3 During the baseline monitoring, the depths of waters at the monitoring stations were all less than 3 m. Thus, only mid-depth samples were collected. For in situ measurements, duplicate readings were made at each station. Duplicate water samples were also collected at each station. 3.4.4 In-situ monitoring instruments for water quality parameters 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 measurement at each monitoring day. 3.5 Laboratory Measurement and Analysis 3.5.1 Analysis of SS was carried out in a HOKLAS accredited laboratory, Acumen Laboratory and Testing Limited (Reg. No. HOKLAS 241). Sufficient water samples were collected at each of the monitoring stations for carrying out the laboratory SS determination. 3.5.2 The SS determination works started within 24 hours after collection of the water samples. The analysis followed the APHA 2540D analytical method with the detection limit of 1.0 mg/L. The quality assurance and quality control results are presented in Appendix D. The HOKLAS Laboratory Certificate is attached in Appendix F.

3.5.3 Parameters for laboratory measurements, their standard methods and the detection limits are presented in Table 3.6.

Table 3.6 Analytical Methods Applied to Water Quality Samples

Parameter	Standard Method	Detection Limit	Accuracy
Suspended Solids (mg/L)	APHA 2540D	1.0 mg/L	±17%

3.6 Results and Observations 3.6.1 The baseline water quality monitoring was conducted from 3 May 2022 to 29 May 2022 at all six monitoring stations (i.e., U1, U2, SW, HT, TKW1, TKW) (Figure 3.2). No construction activities of the Project were conducted in the vicinity of the monitoring locations and in the project site. 3.6.2 The monitoring results are summarized in Table 3.7. Details of water quality monitoring results are presented in Appendix C.

Table 3.7 Summary of Baseline Water Quality Monitoring Results

Locations		Parameters
Locations		Temperature (°C)	pH	DO (mg/L) (Middle)	Turbidity (NTU)	SS (mg/L)
U1	Avg.	22.6	8.1	7.3	17.5	12.8
	Min.	19.9	7.3	4.3	4.7	3.7
	Max.	26.8	9.1	10.5	53.2	36.0
U2	Avg.	22.7	7.9	7.1	8.3	5.4
	Min.	20.3	7.3	3.4	2.5	1.3
	Max.	26.3	8.6	10.7	24.3	16.0
SW	Avg.	22.7	7.9	7.2	11.5	6.2
	Min.	20.2	7.4	3.5	1.9	<1.0
	Max.	26.4	8.6	10.7	23.2	24.0
HT	Avg.	22.6	8.0	6.9	16.2	15.4
	Min.	20.2	7.3	2.2	2.8	<1.0
	Max.	26.1	8.7	10.6	45.1	69.0
TKW1	Avg.	22.7	8.0	7.7	14.3	9.4
	Min.	20.3	7.4	2.8	3.4	<1.0
	Max.	26.4	8.7	10.8	63.2	54.0
TKW	Avg.	22.7	7.9	7.0	14.4	10.2
	Min.	20.2	7.4	2.4	4.0	<1.0
	Max.	26.3	8.7	10.3	57.3	52.0

3.6.3 During the baseline water quality monitoring, significant high pH value was observed at all monitoring stations on 14, 24 and 29 May 2022 with range from 8.5 to 9.1. The particularly high pH values at all monitoring stations appear unusual but are potentially attributed to the domestic discharge from unsewered village and contaminated water from nearby brownfield site. 3.6.4 The baseline water quality monitoring results also indicated that fluctuations of turbidity and SS levels varied over time. It is noticed that extraordinarily high levels of turbidity and SS that might not truly reflect the background condition were occasionally recorded during the baseline monitoring. Without knowing the reasons of these high levels, the turbidity and SS data that are considered as outliers are excluded in the formulation of the Action and Limit Levels. 3.6.5 According to the EIA Report (Register No. AEIAR-203/2016) Section 5 Water Quality Impact, water quality sampling was conducted during the EIA Study, the river quality of Tin Shui Wai Main Channel, Hang Hau Tsuen Channel was subjected to domestic discharge from unsewered villages or expedient connections/ contaminated run-off in the study area. 3.6.6 As the proposed construction of interim section of new distributor road (Road D1) are surrounded by the existing villages and brownfield sites/ open storage areas, watercourses are likely receiving expedient connections of sewage from these villages and contaminated run-off from the brownfield sites/ open storage areas. Thus, the water quality would be affected by the runoff and effluent from the nearby villages and brownfield sites during the impact water quality monitoring. 3.6.7 In contrast to wet season, rainfall is less during dry season and the volume of stream flow is usually lower. The background water quality conditions during the wet and dry seasons would also be different. Therefore, it is recommended to regularly review the water quality baseline conditions during the construction phase of the Project. The environmental performance criteria may need to be re-established if it is evident that the baseline conditions have changed significantly. Updated baseline data should then be sought for re-establishment of the updated environmental performance criteria.

3.7 Action and Limit Levels 3.7.1 The Action and Limit Levels were derived following the approach specified in the Updated EM&A Manual as shown in Table 3.8 below.

Table 3.8 Determination of Action and Limit Levels of Water Quality for Impact Monitoring

Parameters	Action	Limit
DO in mg/L	Surface and Middle, Bottom DO ≤5%-ile of baseline data	Surface and Middle DO ≤4 mg/L and 1%-ile of baseline data for surface and middle layers Bottom DO ≤2 mg/L and 1%-ile of baseline data for bottom layer
SS in mg/L	Depth-averaged SS · ≥ 95%-ile of baseline data or · 120% of upstream control station of the same day (applicable to station at SW and HT only)	Depth-averaged SS · ≥ 99%-ile of baseline data or · 130% of upstream control station of the same day (applicable to station at SW and HT only)
Turbidity in NTU	Depth-averaged Turbidity · ≥ 95%-ile of baseline data or · 120% of upstream control station of the same day (applicable to station at SW and HT only)	Depth-averaged Turbidity · ≥ 99%-ile of baseline data or · 130% of upstream control station of the same day (applicable to station at SW and HT only
pH	Beyond the range 6.6 8.4	Beyond the range of 6.5 8.5

Note:

(1) For DO, non-compliance of the water quality limit occurs when monitoring result is lower than the limit.

(2) For SS and turbidity, non-compliance of the water quality limit occurs when monitoring result is higher than the limit.

3.7.2 Based on the baseline water quality monitoring data and the approach specified above, the Action and Limit Levels were derived and are presented in Table 3.9. As discussed in Section 3.6.4, the extraordinarily high values of turbidity and SS data recorded during the baseline monitoring were excluded in the determination of Action and Limit Levels.

Table 3.9 Derived Action and Limit Levels for Water Quality

Parameters	Action Levels	Limit Levels
SW
DO (mg/L)	3.7	3.5
Turbidity (NTU)	21.4	22.9
SS (mg/L)	9.7	9.9
pH	Less than 6.6 or greater than 8.4	Less than 6.5 or greater than 8.5
HT
DO (mg/L)	2.4	2.2
Turbidity (NTU)	32.3	32.6
SS (mg/L)	34.0	38.7
pH	Less than 6.6 or greater than 8.4	Less than 6.5 or greater than 8.5
TKW1
DO (mg/L)	2.8	2.8
Turbidity (NTU)	27.9	29.2
SS (mg/L)	16.0	18.4
pH	Less than 6.6 or greater than 8.4	Less than 6.5 or greater than 8.5
TKW
DO (mg/L)	2.5	2.4
Turbidity (NTU)	24.2	24.6
SS (mg/L)	19.8	21.6
pH	Less than 6.6 or greater than 8.4	Less than 6.5 or greater than 8.5

Notes:

(1) For DO, non-compliance of the water quality limit occurs when monitoring result is lower than the limit.

(2) For Turbidity and SS, non-compliance of the water quality limit occurs when monitoring result is higher than the limit.

(3) The derived Action Levels and Limit Levels for dissolved oxygen only apply to mid-depth.

4 COMMENTS AND CONCLUSION 4.1 Revision for Inclusion in the EM&A Manual 4.1.1 The baseline monitoring was conducted according to the Updated EM&A Manual for air quality and water quality. 4.1.2 All updated air quality and water quality monitoring locations were verified by the IEC and approved by the EPD. 4.1.3 The monitoring methodology, parameters monitored, and monitoring locations are all generally in line with the Updated EM&A Manual for the Project. 4.2 Air Quality 4.2.1 Baseline air quality monitoring was carried out between 9 December 2021 and 22 December 2021 at three monitoring stations. 4.2.2 No construction activity of the Project was conducted in the vicinity of the monitoring locations and in the project site. 4.2.3 Action and Limit Levels were derived from the baseline 1-hour TSP monitoring results according to the Updated EM&A Manual. 4.3 Water Quality 4.3.1 Baseline water quality monitoring was conducted between 3 May 2022 to 29 May 2022 at six monitoring stations (i.e. U1, U2, SW, HT, TKW1 and TKW). 4.3.2 Action and Limit Levels were derived from the baseline water quality monitoring results according to the Updated EM&A Manual. 4.4 Comments/ Recommendations 4.4.1 The baseline water quality monitoring was conducted during a typical wet season in Hong Kong. During the dry season, however, the rainfall is less, and the stream flow would contain higher portion of expedient discharge from local village houses and contaminated runoff from brownfield sites/ open storage area. It is anticipated that the stream flow would contain higher content of turbidity and SS during the dry season. Thus, review of the water quality baseline condition would be required during the construction phase of the Project, particularly when the non-project related exceedances of Action and Limit Levels become frequent. The environmental performance criteria may need to be updated if it is evident that the baseline conditions have changed significantly. If feasible, a supplementary baseline EM&A programme would be carried out to collect the latest background water quality data for review and updating of the environmental performance criteria.

Rev.	Description of Modification	Date
0.	First issue for comments	14/7/2022
1.	Revised according to IECs comment	17/8/2022
2.	Revised according to IECs comment	26/8/2022
3.	Revised according to IECs comment	20/9/2022
4.	Revised according to IECs comment	30/9/2022
5.	Revised according to IECs comment	7/10/2022

Monitoring Station (s)	TSP Concentration, μg/m3
Monitoring Station (s)	Average	Min.	Max.
AM23 - Planned Port Back-up, Storage and Workshop (at Site 3-6)	62.1	51.0	71.0
AM24 - Planned Port Back-up, Storage and Workshop (at Site 3-8)	61.5	51.0	70.0
AM25a - San Wai Sewage Treatment Plant near the Planned Port Back-up, Storage and Workshop (at Site 3-14)	77.2	62.0	98.0

Monitoring Station(s)	Action Level (µg/m3)	Limit Level (µg/m3)
AM23	290.4	500
AM24	290.0
AM25a	300.2