Job No.: TCS00874/16

 

 

 

 

 

 

 

 

 

CEDD Contract No. CV/2012/05

Development of a Bathing Beach at Lung Mei, Tai Po

 

 

 

 

 

 

 

 

 

Baseline Monitoring Report
(Water Quality Monitoring)

 

 

 

 

 

 

 

 

 

 

Prepared For

 

 

 

 

Welcome Construction CO., Ltd

 

 

 

 

 

 

 

 

 

 

Date

Reference No.

Prepared By

Certified By

19 December 2017

TCS

00874/16/600/R0036v2

Donald Kwok

Assistant Environmental Consultant

T.W. Tam

Environmental Team Leader

 

Version

Date

Remarks

1

14 November 2017

First Submission

2

19 December 2017

Amended according to the IEC’s comment on 12 December 2017

 

 

 

 

 

 

 

 

 


 

 

 

 

executive summary

ES.01     Civil Engineering and Development Department (hereafter referred as “CEDD”) is the Project Proponent and the Permit Holder of Agreement No. CE 59/2005 (EP) Development of a Bathing Beach at Lung Mei, Tai Po (hereinafter referred as “the Project”), which is a Designated Project to be implemented under Environmental Permit number EP-388/2010 (hereinafter referred as “the EP-388/2010” or “the EP”).

ES.02     Action-United Environmental Services & Consulting (hereinafter referred as “AUES”) has been commissioned as the Environmental Team for the Project (hereinafter referred as “the ET”) to perform relevant Environmental Monitoring and Audit (EM&A) programme, including baseline and impact environmental monitoring in accordance with the EM&A Manual approved under the Environmental Impact Assessment Ordinance (EIAO).

ES.03     According to the Approved Environmental Monitoring and Audit (EM&A) Manual [November 2007] (hereinafter referred as ‘the EM&A Manual’), air quality, construction noise and water quality monitoring should be required to be monitored during the construction phase of the Project.  Moreover, baseline environmental monitoring for air quality and water quality is required to be conducted prior to commencement of the construction works/activities under the Project. 

ES.04     Baseline water quality monitoring, which comprise with 3 sampling days a week, have been undertaken at the proposed monitoring locations from 23 September2017 to 21 October 2017.  During the baseline monitoring period, no construction activities under the Project were observed by ET.  However, unknown muddy water discharged from existing box culvert at Lung Mei near lamp post AE0709 was observed by the ET at around 11:45am on 29th September 2017 as external influencing factors of significant concern. The muddy water was trapped and accumulated in inner beach of Lung Mei instead of flowing to outer harbor. Having reviewed both in-situ measurement result and laboratory testing result on 29 September 2017, no abnormal variation was found on the baseline monitoring results at the closest stations including I1, I2, I3 and W1.

ES.05     This Baseline Monitoring Report summarizes the key findings and presents the process and rationale behind determining a set of Action and Limit Levels (A/L Levels) of water quality based on the baseline data. These A/L Levels will serve as the yardsticks for assessing the acceptability of the environmental impact during construction phase of the Project Works impact monitoring. They are statistical in nature and derived according to the criteria set out in the EM&A Manual.

ES.06     Results of the derived Action and Limit Levels for the water quality are given in Tables ES-1 as follows.

Table ES-1       Action and Limit Levels of Water Quality Monitoring

Monitoring Location

Depth Average of SS (mg/L)

Action Level

Limit Level

I1

7.0

OR 120% of any reference stations at the same tide of the same day

7.5

OR 130% of any reference stations at the same tide of the same day

I2

7.0

8.1

I3

8.3

15.0

W1

8.0

8.6

M1

10.0

11.0

FCZ1

7.0

8.0

 

Monitoring Location

Chlorophyll-a (μg/L)

Surface, Middle & Bottom

Action Level

Limit Level

I1

11.1

12.1

I2

11.0

13.1

I3

11.3

14.5

W1

11.3

16.1

M1

16.9

42.4

FCZ1

11.8

12.5


 

 

 



Monitoring Location

Dissolved Oxygen (mg/L)

Depth Average of Surface and Mid-depth

Bottom

Action Level

Limit Level

Action Level

Limit Level

I1

5.08

4.80

N/A

N/A

I2

5.26

4.88

3.64

3.37

I3

5.03

4.77

4.09

3.19

W1

4.67

4.54

2.41

2.33

M1

4.73

4.70

N/A

N/A

FCZ1

5

5

3.43

3.18

 

Monitoring Location

Depth Average of Turbidity (NTU)

Action Level

Limit Level

I1

2.8

OR 120% of any reference stations at the same tide of the same day

2.9

OR 130% of any reference stations at the same tide of the same day

I2

3.5

7.7

I3

2.6

3.0

W1

2.9

3.3

M1

5.2

6.6

FCZ1

3.2

3.4

Notes:

(a)       For DO, non-compliance of water quality limits occurs when monitoring result is lower than the limits

(b)      For SS, chlorophyll-a and turbidity, non-compliance of the water quality limits occurs when monitoring result is higher than the limits.

(c)       In accordance with EM&A Manual Table 5.1, both Action and Limit Levels for DO (surface and middle) in the FCZ1 are less than 5 mg/L.

 

ES.07     In cases where exceedance of these criteria occurs, actions should be carried out in accordance with the Event and Action Plan as shown the EM&A Manual.


Table of Contents

1     Introduction   1

1.1            Project Background   1

1.2            Report Structure  1

2     Summary of Baseline Monitoring Requirement   2

2.1            General  2

2.2            Monitoring Parameters  2

2.3            Monitoring Locations  2

2.4            Monitoring Frequency and Period   3

2.5            Monitoring Equipment  3

2.6            Derivation of Action/Limit (A/L) Levels  4

3     Baseline monitoring methdology   6

3.1            General  6

3.2            Location of Baseline Monitoring   6

3.3            Monitoring Equipment at Baseline Monitoring   6

3.4            Baseline Monitoring Procedures  6

3.5            Data Management and Data QA/QC Control  8

4     Baseline Monitoring Results  9

4.1            General  9

4.2            Results of Water Quality Monitoring   9

4.3            Discussion and Recommendations  11

5     Conclusions and Recommentations  12

5.1            Conclusions  12

5.2            Recommendations  13

 

 

List of TABLES

Table 2-1        Summary of EM&A Requirements

Table 2-2        Location of Water Quality Monitoring Station

Table 2-3        Derivation of Action and Limit Levels for Water Quality

Table 3-1        Water Quality Monitoring Equipment

Table 3-2        Testing Method and Reporting Limit of the Chemical Analysis

Table 4-1        Details of Water Quality Monitoring Stations

Table 4-2        Summary of Water Quality Monitoring Results

Table 4-3        Action and Limit Levels for Water Quality Monitoring

 

 

List of Appendices

Appendix A    Layout Plan of the Project

Appendix B    Designated Monitoring Locations of Water Quality Monitoring

Appendix C    Event and Action Plan

Appendix D    Valid Calibration Certificate of Monitoring Equipment

Appendix E    HOKLAS-accreditation Certificate of the Testing Laboratory.

Appendix F     In-situ Measurements and Laboratory Analysis Data of Water Quality

Appendix G   Baseline Monitoring Schedules

Appendix H    Meteorological Data during Baseline Monitoring (Tai Po Station/ Tai Mei Tuk Station)

 

 

 


1                             Introduction

1.1              Project Background

1.1.1                 Civil Engineering and Development Department (hereafter referred as “CEDD”) is the Project Proponent and the Permit Holder of Agreement No. CE 59/2005 (EP) Development of a Bathing Beach at Lung Mei, Tai Po (hereinafter referred as “the Project”), which is a Designated Project to be implemented under Environmental Permit number EP-388/2010 (hereinafter referred as “the EP-388/2010” or “the EP”). 

 

1.1.2                 The major construction activities of the Project comprise construction 200-metre long bathing beach with a groyne at each end, a shark prevention net; a public car park; retaining walls; and the associated roadworks, drainage and sewerage works.  Layout plan of the Project is shown in Appendix A.

 

1.1.3                 Furthermore, the project works is under Environmental Permit (EP) No. EP-388/2010 as a Designated Project and the designated works include:

(i)            Construction of a 200m long beach with a groyne at each end of the beach which includes dredging and sandfilling works;

(ii)          Construction of one culvert at the eastern side of the beach and another small section of culvert and open drainage channel with gabion embankments at the western end, both to collect and divert surface runoff from upstream locations; and

(iii)        Construction of a beach building with associated beach building facilities, kiosk and a carpark and associated road improvement works adjoining the facility.

 

1.1.4                 Action-United Environmental Services & Consulting (hereinafter referred as “AUES”) has been commissioned as an Independent Environmental Team (hereinafter referred as “the ET”) to implement the relevant EM&A program in accordance with the approved EM&A Manual, as well as the associated duties.  As part of the EM&A program, baseline monitoring is required to determine the ambient environmental conditions.  The baseline monitoring of air quality had been undertaken on 7 June 2017 to 20 June 2017 and baseline noise monitoring had been carried out on 7 June 2017 to 23 June 2017 before construction work commencement.  The baseline monitoring report (air quality and noise) (reference no.: TCS00874/16/600/R0022v3) was submitted by RE to EPD on 11 September 2017 after verification by IEC. With regard to the baseline water quality monitoring, it was carried from 23 September 2017 to 21 October 2017 before construction work commencement including the dredging and sandfilling activities.  

 

1.1.5                 During the baseline monitoring period for water quality, there were no construction activities of this project observed by the ET. However, unknown muddy water discharged from existing box culvert at Lung Mei near lamp post AE0709 was observed by the ET in the morning of 29th September 2017 as external influencing factors of significant concern. The muddy water was trapped and accumulated in inner beach of Lung Mei instead of flowing to outer harbor. Having reviewed both in-situ measurement result and laboratory testing result dated on 29 September 2017, no abnormal variation was found on the baseline monitoring results at the closest stations including I1, I2, I3 and W1.

 

1.1.6                 This Baseline Monitoring Report for Water Quality presents the details of the baseline study including project background, monitoring methodology, monitoring results, summary of findings, and Action/Limit (A/L) Levels established for subsequent use in the Project construction phase EM&A program.

 

1.2              Report Structure

1.2.1                 The Baseline Monitoring Report (Water Quality Monitoring)is structured into the following sections:-

Section 1    Introduction

Section 2    Summaries of Baseline Monitoring Requirement.

Section 3    Baseline Monitoring Methodology

Section 4    Baseline Monitoring Results

Section 5    Conclusion and Recommendation


2                             Summary of Baseline Monitoring Requirement

2.1              General

2.1.1                 The Environmental Monitoring and Audit requirements are set out in the EM&A manual. Environmental issue such as water quality was identified as the key issues during the construction phase of the Project.  A summary of the baseline EM&A requirements for water quality monitoring are presented in the sub-sections below.

 

2.2              Monitoring Parameters

2.1.2                 According to the EM&A Manual, baseline monitoring shall only cover air and water quality. This is a standalone baseline report for water quality and the corresponding monitoring parameters are presented in the following sections.

 

2.2.1                 A summary of the monitoring parameters in accordance to EM&A Manual Sections 5.1 is presented in Table 2-1 below.

Table 2-1         Summary of EM&A Requirements

Environmental Issue

Parameters

Water Quality

In-situ Measurements

Ÿ  Dissolved Oxygen Concentration (mg/L);

Ÿ  Dissolved Oxygen Saturation (% );

Ÿ  Salinity (mg/L);

Ÿ  Temperature ();

Ÿ  Turbidity (NTU);

Ÿ  pH unit;

Ÿ  Current direction (degree);

Ÿ  Current speed (m/s); and

Ÿ  Water depth (m).

Laboratory Analysis

Ÿ  Suspended Solids (mg/L); and

Ÿ  Chlorophyll-a (µg/L)

 

2.3              Monitoring Locations

Water Quality

2.3.1                 According to EM&A Manual Sections 5.1.2, two Reference Stations (R1 and R2), three impact stations (I1, I2 and I3), three sensitive receivers (FCZ1, W1 and M1) and one Gradient station (G1), were recommended in the EM&A Manual Section 5.1.2 to perform water quality monitoring.  Detailed and co-ordnance of water quality monitoring stations is described in Table 2-2 and the graphical is shown in Annex B. 

Table 2-2         Location of Water Quality Monitoring Station

Station

Coordinates

Description

Easting

Northing

R1

842307.4

835718.4

Reference Station - for the background water quality for Tolo Harbour as it is at the channel where the water exchange between the enclosed Plover Cove and Tolo Harbour take place. It is located at south of the Project dredging/sandfilling area.

R2

840739.4

836212.4

Reference Station - for the background water quality in the Plover Cove region.  It is located at southwest of the Project dredging/sandfilling area.

I1

841338.5

836588.5

Impact Station - located outside the mixing zone of dredging/sandfilling works of the Project.

I2

841590.3

836601.2

Impact Station - located outside the mixing zone of dredging/sandfilling works of the Project.

I3

841807.0

836680.9

Impact Station - located outside the mixing zone of dredging/sandfilling works of the Project.

FCZ1

841180.6

835230.8

Sensitive Receiver - located at the Yim Tin Tsai East Fish Culture Zone, which is about 1.5 km distance to the southwest of the dredging/sandfilling area.

W1

841858.9

836571.0

Sensitive Receiver - located at the Water Sport Centre, which is about 0.25 km distance to the southeast of the dredging/sandfilling area.

M1

840822.2

836416.4

Sensitive Receiver - located at the Ting Kok SSSI, which is about 0.8 km distance to the west of the dredging/sandfilling area.

G1

841483.9

835936.1

Gradient Station - to assist in the identification of the source of any impact.

 

2.4              Monitoring Frequency and Period

2.4.1                 Baseline monitoring to be carried out in the EM&A programme is basically in accordance with the requirements in EM&A Manual Sections 5.1.3 and 5.1.4.  The monitoring requirements are listed as follows:

 

Water Quality Monitoring

Parameters:

Duplicate in-situ measurements: water depth, temperature, Dissolved Oxygen, pH, turbidity and salinity;

HOKLAS-accredited laboratory analysis: Suspended Solids and Chlorophyll-a.

Frequency:

Three days per week, at mid-ebb and mid-flood tides.  The interval between 2 monitoring days will be more than 36 hours.

Sampling Depth:

(i.)       Three depths: 1m below water surface, 1m above sea bottom and at mid-depth when the water depth exceeds 6m. 

(ii.)     If the water depth is between 3m and 6m, two depths: 1m below water surface and 1m above sea bottom.

(iii.)   If the water depth is less than 3m, 1 sample at mid-depth is taken

Duration:

4 weeks prior to the commencement of construction works

 

2.5              Monitoring Equipment

Water Quality Monitoring

2.5.1                 For water quality monitoring, the equipment should fulfill the requirement under the EM&A Manual Section 5.1.1. The requirement is summarized in the following section.

 

2.5.2                 Dissolved Oxygen and Temperature Measuring Equipment – The instrument should be a portable, weatherproof dissolved oxygen measuring instrument completed with cable, sensor, comprehensive operation manuals, and should be operable from a DC power source. It should be capable of measuring: dissolved oxygen levels in the range of 0-20 mg L-1 and 0-200% saturation; and a temperature of 0-45 degrees Celsius. It should have a membrane electrode with automatic temperature compensation complete with a cable of not less than 35 m in length. Sufficient stocks of spare electrodes and cable should be available for replacement where necessary.

 

2.5.3                 Turbidity Measurement Equipment – The instrument shall be a portable, weatherproof turbidity-measuring instrument complete with comprehensive operation manual. The equipment shall use a DC power source. It shall have a photoelectric sensor capable of measuring turbidity between 0-1000 NTU.

 

2.5.4                 Salinity Measurement Instrument – A portable salinometer capable of measuring salinity in the range of 0-40 ppm should be provided for measuring salinity of the water at each monitoring location.

 

2.5.5                 Water Depth Detector – A portable, battery-operated echo sounder should be used for the determination of water depth at each designated monitoring station. A detector affixed to the bottom of the works boat, if the same vessel is to be used throughout the monitoring programme, is preferred.

 

2.5.6                 Current Velocity and Direction – No specific equipment is recommended for measuring the current velocity and direction. Hence, Valeport Ltd – Model 106 Self Recording/Direct Reading Current Meter was proposed to be used for the measurement of current velocity and direction.

 

2.5.7                 Positioning Device – hand-held or boat-fixed type digital Global Positioning System (GPS) with way point bearing indication or other equipment instrument of similar accuracy, should be provided and used during water quality monitoring to ensure the monitoring vessel is at the correct location before taking measurements. GPS or the equivalent instrument, calibrated at appropriate checkpoint(e.g. Quarry Bay Survey Nail at Easting 840683.49, Northing 816709.55) should be provided and used to ensure the monitoring station is at the correct position before taking measurement.

 

2.5.8                 Water Sampling Equipment – A water sampler, consisting of a transparent PVC or glass cylinder of not less than two liters, which can be effectively sealed with cups at both ends, should be used. The water sampler should have a positive latching system to keep it open and prevent premature closure until released by a messenger when the sampler is at the selected water depth.

 

2.6              Derivation of Action/Limit (A/L) Levels

2.6.1                 The baseline results form the basis for determining the environmental acceptance criteria for the impact monitoring.  A summary of derivation of Action/Limit (A/L) Levels for water quality is shown in Table 2-4 respectively.

Table 2-4        Derivation of Action and Limit Levels for Water Quality

Parameter

Action Level

Limit Level

SS in mg/L

(depth-averaged (a)) (c)

95%-ile of baseline data, or 20% exceedance of value at any impact station and sensitive receiver compared with corresponding data from reference stations at the same

tide of the same day

99%-ile of baseline data, or 30% exceedance of value at any impact station and sensitive receiver compared with corresponding data from reference stations at the same tide of the same day and specific sensitive receiver water quality requirements

Chlorophyll-a in μg/L(c)

Surface, Middle and Bottom

95%-ile of baseline data

Surface, Middle and Bottom

10μg/L or 99%-ile of baseline data

DO in mg/L (b) (d)

Surface and Middle

5%-ile of baseline data for surface and middle layer

Bottom

5%-ile of baseline data for bottom layers

Surface and Middle

4mg/L or 1%-ile of baseline for surface and middle layer

Bottom

2mg/L or 1%-ile of baseline data for bottom layer

Turbidity in NTU

(depth-averaged (a)) (c)

95%-ile of baseline data, or 20% exceedance of value at any impact station and sensitive receiver compared with corresponding data from reference stations at the same tide of the same day

99%-ile of baseline data, or 30% exceedance of value at any impact station and sensitive receiver compared with corresponding data from reference stations at the same tide of the same day

Notes:

(a)        “Depth-averaged” is calculated by taking the arithmetic means of reading of all three depths.

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

(c)       For SS, chlorophyll-a and turbidity, non-compliance of the water quality limits occurs when monitoring result is higher than the limits.

(d)      Both Action and Limit Levels for DO (surface and middle) in the FCZ1 (Figure 5.1) are less than 5 mg/L.

 

Event Action Plan

2.6.2                 Should non-compliance of the environmental quality criteria occurs, remedial actions will be triggered according to the Event and Action Plan which presented in Appendix D.

 


3                             Baseline monitoring methdology

3.1              General

3.1.1                 The baseline monitoring program of water quality was conducted from 23 September 2017 to 21 October 2017.  During the baseline monitoring period, there were no construction activities of this project was observed by the ET.  However, unknown muddy water discharged from existing box culvert at Lung Mei near lamp post AE0709 on the morning of 29th September 2017 was observed by the ET as external influencing factors of significant concern. It was observed that the muddy water was trapped and accumulated in inner beach of Lung Mei instead of flowing to outer harbor. Having reviewed both in-situ measurement result and laboratory testing result dated on 29 September 2017, no significant variation was found on the baseline monitoring results at I1, I2, I3 and W1 on 29 September 2017.

 

3.2              Location of Baseline Monitoring

3.2.1                 Baseline water quality monitoring has been undertaken at the all designated monitoring stations from 23 September 2017 to 21 October 2017.  The detailed information of monitoring stations to be referred to Tables 2-2 and Appendix B.

 

3.3              Monitoring Equipment at Baseline Monitoring

3.3.1                 The monitoring equipment using for the EM&A program was proposed by ET and verified by prior of baseline monitoring work commencement.  The detail of equipment using for baseline monitoring is listed in Table 3-1 as below.

Table 3-1         Water Monitoring Equipment

Equipment

Model

A Digital Global Positioning System

GPS12 Garmin

Water Depth Detector

Eagle Sonar CUDA 300

Water Sampler

A 2-litre transparent PVC cylinder with latex cups at both ends or teflon/stainless steel bailer or self-made sampler

Thermometer & DO meter

YSI ProDSS Digital Sampling System Water Quality Meter or YSI Professional Plus Multifunctional Meter

pH meter

YSI ProDSS Digital Sampling System Water Quality Meter or YSI Professional Plus Multifunctional Meter

Turbidimeter

YSI ProDSS Digital Sampling System Water Quality Meter or Hach 2100p

Salinometer

YSI ProDSS Digital Sampling System Water Quality Meter or YSI Professional Plus Multifunctional Meter

Current Meter

Valeport Ltd – Model 106 Self Recording/Direct Reading Current Meter

Sample Container

High density polythene bottles (provided by laboratory)

Storage Container

‘Willow’ 33-litter plastic cool box with Ice pad

 

3.4              Baseline Monitoring Procedures

Water Quality

3.4.1                 Marine water quality monitoring will be conducted at the designated locations in accordance with EM&A Manual. The operating and analytical of sampling procedures are described as below:

Ÿ  A Global Positioning System (GPS) will be used to ensure that the correct location was selected prior to sample collection.  A portable, battery-operated echo sounder will be used for the determination of water depth at each designated monitoring station.

Ÿ  The marine water sampler will be lowered into the water body at a predetermined depth. The trigger system of the sampler is activated with a messenger and opening ends of the sampler are closed accordingly then the sample of water is collected.

Ÿ  During the sampling, the sampling container will be rinsed to use a portion of the marine water sample before the water sample is transferred to the container.  Upon sampling completion, the container is sealed with a screw cap.

Ÿ  Before the sampling process, general information such as the date and time of sampling, weather condition and tidal condition as well as the personnel responsible for the monitoring will be recorded on the monitoring field data sheet.

Ÿ  In-situ measurement including water temperature, turbidity, dissolved oxygen, salinity, pH and water depth undertake at the identified monitoring point.  At each station, marine water samples are collected at three depths: 1m below water surface, 1m above sea bottom and at mid-depth when the water depth exceeds 6m.  Samples at 1m below water surface and 1m above sea bottom are collected when the water depth is between 3m and 6m.  Only 1 sample at mid-depth is taken when the water depth is below 3m.

Ÿ  For the in-situ measurement, two consecutive measurements of sampling depth, temperature, dissolved oxygen, salinity, turbidity and pH concentration will be measured at the sea. The YSI ProDSS Multifunctional Meter is retrieved out of the water after the first measurement and then re-deployed for the second measurement.  Where the difference in the value between the first and second readings of each set is more than 25% of the value of the first reading, the reading is discarded and further readings is taken.

Ÿ  Water sample collection would be used the water sampler.  During the water sample collected from the sea, it is fill in high-density polythene bottles.  Before the water sample storage, the sampling bottles will be pre-rinsed with the same water sample.  The sample bottles then is packed in cool-boxes (cooled at 4OC without being frozen), and delivered to HOKLAS accredited laboratory for the chemical analysis as followed APHA Standard Methods. 

Ÿ  The laboratory has be comprehensive quality assurance and quality control programmes.  For QA/QC procedures, one duplicate sample of every batch of 20 samples is analyzed as followed the HOKLAS accredited requirement.

 

3.4.2                 During marine water sampling period, all in-situ measurement equipment will be calibrated at three months interval accordingly. Except for the Current Velocity and Direction water flow meter will be calibrated every two years as recommended by the manufactory.   Available calibration certificates will be issued to ensure the performance of equipment to use for in-situ measurement.

 

3.4.3                 Before each round of monitoring, the dissolved oxygen probe will be calibrated by wet bulb method; a zero check in distilled water will be performed with the turbidity and salinity probes; 4 and 10 values of the standard solution will be undertaken to check the accuracy of pH value.

 

3.4.4                 The calibration certificates of monitoring equipment of water quality and the HOKLAS-Accreditation certificate of the testing laboratory is shown in Appendices D and E.

 

Laboratory Analysis

3.4.5                 All water samples included the duplicate samples, will be conducted the chemical analysis as specified in the EM&A Manual by a HOKALS accredited laboratory - ALS Technichem (HK) Pty Ltd.  The chemicals analysis method and reporting limit show Table 3-2.

Table 3-2         Testing Method and Reporting Limit of the Chemical Analysis

Parameter

ALS Method Code

In-house Method Reference 1

Reporting Limit

Total Suspended Solids

EA025

APHA 2540D

2 mg/L

Chlorophyll-a

EP008F

APHA 10200 H2&H3

0.1 μg/L

Note:

1.      The exact method shall depend on the laboratory accredited method. APHA = Standard Methods for the Examination of Water and Wastewater by the American Public Health Association.

 

3.4.6                 The determination works should start within 24 hours after collection of the water samples or within the holding time as advised by the laboratory.

 

Meteorological Information

3.4.7                 The meteorological information including wind direction, wind speed, humidity, rainfall, air pressure and temperature etc. during baseline monitoring is extracted from the closest Hong Kong Observatory Station.  To obtain the most appropriate meteorological information where available, Air Temperature/Pressure and Relative Humidity will be extracted from Tai Po Station and wind speed and direction will be extracted from Tai Mei Tuk Station.

 

3.5              Data Management and Data QA/QC Control

3.5.1                 The baseline monitoring data were handled by the ET’s in-house data recording and management system.

 

3.5.2                 The monitoring data recorded in the equipment were downloaded directly from the equipment at the end of each monitoring day.  The downloaded monitoring data were input into a computerized database properly maintained by the ET.  The laboratory results were input directly into the computerized database and checked by personnel other than those who input the data.

 

3.5.3                 For monitoring parameters that require laboratory analysis, the local laboratory shall follow the QA/QC requirements as set out under the HOKLAS scheme for the relevant laboratory tests.


4                             Baseline Monitoring Results

4.1              General

4.1.1                 The baseline water quality monitoring was originally conducted in the period of 23 September 2017 to 19 October 2017, since tropical cyclone warning signal No.8 was hoisted on 15 October 2017 and the monitoring event was rescheduled on 21 October 2017.  The full period of baseline water quality monitoring was performed on 23 September 2017 to 21 October 2017.

 

4.1.2                 The baseline monitoring schedules are presented in Appendix G and the monitoring results are detailed in the following sub-sections.

 

4.2              Results of Water Quality Monitoring

4.2.1                 The baseline water quality monitoring at nine (9) designated monitoring stations was performed a 4 weeks as between 23 September 2017 and 21 October 2017.  The results at each designated monitoring station are presented in Tables 4-1 and Appendix F.

Table 4-1         Details of Water Quality Monitoring Stations

Monitoring Station

Status

Water Depth, (m)

Co-ordnance

Min

Max

Ave.

East

North

G1

Gradient Station

4.4

7.2

5.7

841483.9

835936.1

I1

Impact Station

2.6

2.9

2.8

841338.5

836588.5

I2

Impact Station

4.5

5.7

4.8

841590.3

836601.2

I3

Impact Station

4.2

5.5

4.8

841807.0

836680.9

R1

Reference Station

5.1

7.3

6.2

842307.4

835718.4

R2

Reference Station

4.2

5.6

4.9

840739.4

836212.4

W1

Sensitive Receiver

6.6

8.4

7.4

841858.9

836571.0

M1

Sensitive Receiver

0.5

1.0

0.7

840822.2

836416.4

FCZ1

Sensitive Receiver

4.1

5.2

4.7

841180.6

835230.8

 

4.2.2                 The monitoring results are summarized in Tables 4-2.  Detailed monitoring results including in-situ measurements and laboratory analysis data are shown in Appendix F.

Table 4-2         Summary of Water Quality Monitoring Results

Suspended Solids – Depth Average (mg/L)

G1

I1

I2

I3

R1

R2

W1

M1

FCZ1

95%-ile

N/A

7.0

7.0

8.3

N/A

N/A

8.0

10.0

7.0

99%-ile

N/A

7.5

8.1

15.0

N/A

N/A

8.6

11.0

8.0

Average

4.1

3.7

3.9

4.2

3.9

4.1

3.8

5.4

4.3

Min

2.0

2.0

2.0

2.0

2.0

2.0

2.0

2.0

2.0

Max

10.0

8.0

10.0

15.0

10.0

10.0

9.0

11.0

8.0

 

Chlorophyll-a

Depth Average (μg/L)

G1

I1

I2

I3

R1

R2

W1

M1

FCZ1

95%-ile

N/A

11.1

11.0

11.3

N/A

N/A

11.3

16.9

11.8

99%-ile

N/A

12.1

13.1

14.5

N/A

N/A

16.1

42.4

12.5

Average

4.5

4.3

3.7

4.0

3.7

7.1

4.1

6.0

5.5

Min

0.2

0.3

0.2

0.3

0.3

0.3

0.4

0.3

0.4

Max

14.8

12.5

14.2

15.3

12.4

83.8

17.1

43.5

13.5

 

Dissolved Oxygen – Depth Average of Surface & Mid-depth (mg/L)

G1

I1

I2

I3

R1

R2

W1

M1

FCZ1

5%-ile

N/A

5.08

5.26

5.03

N/A

N/A

4.67

4.73

5.32

1%-ile

N/A

4.80

4.88

4.77

N/A

N/A

4.54

4.70

4.86

Average

6.30

6.02

6.07

6.00

5.97

6.27

5.77

5.99

6.50

Min

5.10

4.77

4.87

4.72

4.29

5.09

4.27

4.70

4.84

Max

7.53

7.64

7.45

7.75

7.60

8.53

7.83

7.67

8.16

Dissolved Oxygen – Bottom Depth (mg/L)

G1

I1

I2

I3

R1

R2

W1

M1

FCZ1

5%-ile

N/A

N/A

3.64

4.09

N/A

N/A

2.41

N/A

3.43

1%-ile

N/A

N/A

3.37

3.19

N/A

N/A

2.33

N/A

3.18

Average

4.76

N/A

4.93

4.95

4.46

4.74

3.87

N/A

5.25

Min

2.63

N/A

3.35

3.18

2.82

2.09

2.30

N/A

3.15

Max

7.53

N/A

6.24

5.94

5.71

7.28

5.90

N/A

7.71

 

Turbidity –

Depth Average (NTU)

G1

I1

I2

I3

R1

R2

W1

M1

FCZ1

95%-ile

N/A

2.8

3.5

2.6

N/A

N/A

2.9

5.2

3.2

99%-ile

N/A

2.9

7.7

3.0

N/A

N/A

3.3

6.6

3.4

Average

1.9

1.7

1.9

1.6

1.7

1.9

1.7

2.9

1.8

Min

0.1

0.2

0.1

0.1

0.1

0.2

0.1

1.0

0.03

Max

4.1

2.9

7.8

3.0

4.8

3.3

3.6

7.3

3.5

N/A: Not applicable

 

4.2.3                 During the baseline monitoring period, no construction activities under the Project were observed