Report

Time Period	Action Level	Limit Level
0700 – 1900 hours on any day not being a Sunday or public holiday	When one documented complaint is received	75dB(A)*

Parameters	Monitoring locations
DO (mg/L)	5.7	4	6.2	4	5.9	4	5.9	4
SS (mg/L) ^{[1, 2]}	12.2	12.8	3.1	4.2	12.4	17.7	13.9	15.2
Tby (NTU) ^{[1, 2]}	15.2	16.9	5.3	6.5	16.8	26.0	16.2	18.0

Event	Action
Identification of disturbance to breeding White-shouldered Starlings	1. Increase frequency of monitoring to twice weekly	1. Check all construction actions and working methods
2. Notify ER	2. Submit proposals for remedial action to prevent abandonment of the breeding site
3.Review construction activities of previous week	3. Implement remedial action
4. Identify any changes in construction activities in previous week	4. Liaise with ET and IEC regarding effectiveness of remedial actions.
5. Discuss remedial actions with ER

This project relates to the drainage improvement works in Southern Lantau. Most of the watercourses in Mui Wo, Southern Lantau remain untouched at their upper reaches and are partially channelized at their downstream ends near Silver River. Pak Ngan Heung River with Ling Tsui Tau U-channel, Luk Tei Tong River and Tai Tei Tong River merge at Silver River before passing Mui Wo township to Silver Mine Bay. Some drainage improvement works at Cheung Sha River, Cheung Sha Sheung Tsuen, Lo Uk Tsuen, Pui O River in Ham Tin and San Shek Wan are also included. As these existing rivers do not meet flood protection standards, drainage improvement works are recommended accordingly.

A Preliminary Environmental Review (PER), undertaken in the PPFS stage, identified that part of the drainage improvement works in Southern Lantau is a Designated Project under Schedule 2 Part I of the Environmental Impact Assessment Ordinance (EIAO) and requires an Environmental Permit (EP) under the EIAO for its construction and operation. The Designated Project includes the drainage improvement works in Pak Ngan Heung River, Tai Tei Tong River, Luk Tei Tong River and Luk Tei Tong (2) By-pass River in Mui Wo (hereafter referred to as “the Project”). The Environmental Impact Assessment (EIA) Report and the Environmental Monitoring & Audit (EM&A) Manual for the Project had been approved under the EIAO by the Director of Environmental Protection Department (EPD) in December 2005 (Register no. AEIAR-093/2005), and the Variation of EP (VEP) (EP-237/2005/A) was issued in March 2007.

A location map for the Project is provided in Figure 1-1. The scope of work elements covered is described in the following:

Pak Ngan Heung River

A 80m long trapezoidal channel using gabion walls will be constructed with rip-rap bases and natural substrates at upstream of Pak Ngan Heung River.

A 180m long 3-cell by-pass box culvert (3m wide and 2.25m deep) will be constructed. Embankment with landscape works will be formed on the top of the box culvert.

A low flow diversion dam and low flow pipes will be provided at upstream of the meander to maintain the base flow for sustaining the natural habitat of the meander. During heavy flow, the flood waters can be diverted directly to the downstream through the by-pass box culvert. In addition, an agricultural weir and a fish ladder will be provided at the upstream of Pak Ngan Heung River.

A 100m long rectangular channel using rip-rap bedding and concrete retaining walls, with associated maintenance road and access ramp, will be constructed at downstream of Pak Ngan Heung River.

Ling Tsui Tau U-Channel

A 200m long, about 750mm wide U-channel along the downhill slope was originally proposed in the EIA to intercept runoff from Butterfly Hill and convey the flow to Pak Ngan Heung River. Recent application for VEP for a 750mm wide U-channel of about 250m long and upgrading of existing drains of about 130m long has been approved (ref. EP-237/2005/A).

Tai Tei Tong River

The works at Tai Tei Tong River will include widening of 3 bottlenecks. Existing river bed will be untouched. The river bank will be reinstated by gabion blocks.

Luk Tei Tong River and Luk Tei Tong (2) By-pass River

A 240m long trapezoidal channel will be constructed using gabion walls with masonry lined bank and natural bed in Luk Tei Tong River.

A 350m long rectangular By-pass Channel will be constructed at Luk Tei Tong (2) By-pass River passing through the existing marsh area and abandoned agricultural land. The By-pass Channel bed would be approximately 0.8m below the existing ground level, and would be maintained as compensatory marshland habitat. A low flow weir would be constructed at the downstream end of the By-pass Channel, serving to retain rainwater and some diverted flood flow in the channel. Under normal condition, the flow to the existing streamcourse will be maintained. Flood flow can be diverted directly to downstream through the By-pass Channel during high flow events. A minimum of 0.2m high earth embankment to avoid surface runoff from existing marsh overflowing to the proposed By-pass Channel will be erected. One vehicular crossing and one pedestrian crossing will be provided in the form of box culvert.

1.2 Purpose of the Report

According to the EP-237/2005/A, an EM&A programme shall be implemented in accordance with the procedures and requirements as set out in the EM&A Manual of the Project.

An environmental baseline monitoring for noise, water quality, ecology and cultural heritage was undertaken in accordance with the EM&A Manual and EM&A Guidelines for Development Projects in Hong Kong prior to the commencement of any construction activities on-site. The purpose of this report is to summarise the findings of this baseline monitoring and to establish the compliance levels for the subsequent impact monitoring during the construction stage. Other than this introductory section, the report will provide information on the monitoring methodology, monitoring results, derivation of Action and Limit (A/L) Levels, and conclusions.

Figure 1-1: Site location Plan

2 Baseline Monitoring Methodology

2.1 Airborne Construction Noise

2.1.1 Methodology, Monitoring Parameters and Equipment

Baseline noise level was measured by sound level meters in terms of A-weighted equivalent continuous sound pressure level (L_eq) according to the Technical Memorandum on Noise from Construction Work other than Percussive Piling (GW-TM). L₁₀ and L₉₀ were recorded as supplementary information for data auditing. The sound level meters and calibrators comply with the International Electrotechnical Commission (IEC) Publication 651:1979 (Type 1) specification in accordance with GW-TM. The calibration certificates for the noise monitoring equipment are given in Appendix 1. Table 2-1 summarises the equipment list for baseline noise monitoring.

Table 2-1: Equipment list for baseline noise monitoring

Equipment	Manufacturer & Model No.	Precision Grade	Qty.
Integrated sound level meter	Brüel & Kjær 2238	IEC 651 Type 1 IEC 804 Type 1	2
Windshield	Brüel & Kjær UA0237		2
Acoustical calibrator	Brüel & Kjær 4226	IEC 942 Type 1	1
LCD wind speed indicator	Kestrel Vane Anemometer	--	1

Noise measurements were not conducted in the presence of fog, rain, wind with a steady speed exceeding 5m/s or wind with gusts exceeding 10m/s. The wind speed was checked with a portable meter capable of measurement in m/s.

2.1.2 Monitoring Locations

The EM&A Manual specified four locations for noise monitoring including village house in Ling Tsui Tau Tsuen (PNH4), No. 73 village house in Ling Tsui Tau Tsuen (LT2), No 23 village house adjacent to Tai Tei Tong River (TTT3) and No. 4 village house adjacent to Luk Tei Tong River Outlet (LTT4). During the recent site visits in June to October 2007, PNH4 and LTT4 were vacant. The gate for access to PNH4 was locked by the owner. Site access to No. 5 village house just next to LTT4 was not granted by the dweller. The PNH4 and LTT monitoring locations were therefore relocated to No. 31 village house just outside the entrance gate and the fence wall outside No. 5 village house, respectively. Alternative monitoring locations are summarised in Table 2-2 and shown in Figure 2-1.

Table 2-2: Baseline noise monitoring locations

ID	Description ^[1]	Monitoring Period	Remark
N1	No. 73, Village House, Ling Tsui Tau Tsuen (roof height)	9/9/07 to 23/9/07	-
N2	No. 31, Village House, Ling Tsui Tau Tsuen (1^st floor height)	5/10/07 to 19/10/07	The monitoring location was changed due to access restriction from the premises owner of PNH4.
N3^[2]	Fence wall outside No. 5 village house adjacent to Luk Tei Tong River Outlet (equivalent roof height of the nearby village house)	9/9/07 to 23/9/07	The monitoring location was changed due to access restriction from the premises owners of LTT4 and the nearby village house.
N4	No. 23, Village House, Tai Tei Tong River (roof height)	4/10/07 to 19/10/07	-

Note:

[1] Noise measurements were taken at a point 1m from the exterior of the selected premises and at a height with no disturbance to the dweller and least obstructed view.

[2] A +3dB(A) is added to the measured noise level to account for the facade effect.

Figure 2-1: Noise monitoring locations

2.1.3 Monitoring Frequency

Baseline noise monitoring was conducted continuously for two consecutive weeks on weekdays and weekends. The noise level was measured in terms of the A-weighted equivalent continuous sound pressure level (L_eq) in a sample period of 5 minutes L_eq(30min), determined by taking the log average of 6 consecutive L_eq(5min), was reported for the time period between 0700 and 1900 on normal weekdays and L_eq(5min) was reported for all other time periods.

The actual dates of measurement are given in the schedule attached in Appendix 2.

2.2 Water Quality

2.2.1 Water Quality Parameters and Equipment

Turbidity (Tby) in Nephelometric Turbidity Unit (NTU), Dissolved Oxygen (DO) in mg/L and Suspended Solids (SS) in mg/L were monitored for this project. Tby and DO were measured in-situ while samples were delivered to ALS Technichem (HK) Pty Ltd (HKOLAS laboratory) for analysis of SS. A summary of the water quality monitoring equipment is given in Table 2-3.

Table 2-3: Water quality monitoring equipment

Equipment	Manufacturer & Model No.	Qty
Handheld DO, Salinity & Temperature System	YSI 85	1
Turbidimeter	HACH 2100P	1
pH meter	Mettler – Toledo SG2	1
Water Sampler	Wild Co Instrument	1

In association with the water quality parameters, some relevant data were also recorded, such as monitoring location/position, time, water depth, water temperature, salinity, weather conditions, sea conditions, tidal cycle, and any special phenomena and work underway at the construction site, etc.

Dissolved Oxygen and Temperature Measuring Equipment

The equipment to measure DO and temperature complied with the following requirements:

i. The instrument (YSI 85) was a portable, weatherproof dissolved oxygen measuring instrument complete with cable and uses a DC power source. It was capable of measuring:

· A dissolved oxygen level in the range of 0- 20 mg/L and 0-200% saturation; and

· A temperature of 0-45^oC.

ii. It had a membrane electrode with automatic temperature compensation complete with a cable.

iii. It had equipped with a salinity compensation device in the DO equipment.

Turbidity Measurement Instrument

The instrument (Hach model 2100P) was a portable, weatherproof turbidity-measuring instrument. The instrument was operated by a DC power source and had a photoelectric sensor capable of measuring turbidity between 0-1000 NTU.

Suspended Solids

The suspended solids was collected for laboratory testing by the water sampler (Wild Co Instrument) comprising a transparent PVC cylinder, with a capacity of not less than 2L and could be effectively sealed with latex cups at both ends. The sampler had 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.

Water samples for SS measurement of both the marine and freshwater environment was collected in high density polythene bottles, packed in ice (cooled at 4^oC without being frozen) and delivered to the laboratory within 24 hours after collection.

Water Depth Detector

A portable, battery-operated echo sounder was used for the determination of water depth at each designated monitoring.

Salinity

A portable salinometer (YSI Model 85) capable of measuring salinity in the range of 0-40 ppt was provided for measuring salinity of the water at each monitoring location.

Location of the Monitoring Site

A hand-held type DGPS was used during monitoring to ensure that the water sampling locations were correct.

Calibration and Accuracy of Instrumentation

All in-situ monitoring instruments were checked, calibrated and certified by ALS Technichem (HK) Pty Ltd. Responses of sensors and electrodes were checked with certified standard solutions before each use. Wet bulb calibration for the DO meter was carried out before measurement at each monitoring location. The calibration certificates are attached in Appendix 3. For the on site calibration of field equipment, BS 1427:1993, “Guide to Field and on-site test methods for the analysis of waters” was adopted. Table 2-4 gives the detection limits of the in-situ and laboratory measurements.

Table 2-4: Limit of detection of water quality parameters

Determinant	Limit of Detection
DO	0.1 mg/L
Salinity	0.1 ppt
Turbidity	1 NTU
SS	1 mg/L

2.2.2 Monitoring Locations

Seven locations were selected for baseline water quality monitoring and the coordinates are given in Table 2-5 and presented in Figure 2-2. Since access to previous location C1 proposed in the EM&A manual was constrained by dense vegetation and muddy soil along the periphery of the river, the monitoring location was relocated to some 50m downstream at the only accessible location. In addition, the C2 monitoring location was also shifted to some 20m upstream so that the sample could be easily taken at the middle of river channel from the footbridge.

Table 2-5: Baseline water monitoring locations

Water Monitoring Station No.	Location
Water Monitoring Station No.	Eastings	Northings
M1 (Impact Station)	817425	814179
C1 (Control Station)	817270	814501
M2 (Impact Station)	817391	814156
C2 (Control Station)	816952	814227
M3 (Impact Station)	817402	814098
C3 (Control Station)	817356	813834
M4 (Impact Station)	817628	814118

Measurements were taken at mid-water depth at the designated monitoring stations.

Figure 2-2 Water quality monitoring locations

2.2.3 Monitoring Frequency

Baseline water quality monitoring was conducted three times a week for four consecutive weeks to establish the water quality conditions prior to commencement of the construction works. The water quality monitoring was undertaken during ebb tide in accordance with the approved EM&A manual. Duplicate samples from each independent sampling event were taken.

The actual dates of measurement are given in the schedule attached in Appendix 2.

2.3 Ecology

Ecological baseline monitoring was carried out with reference to the requirements stipulated in the Final EM&A Manual. The methodology was proposed in accordance with the observations during the recent field visits.

The ecological baseline monitoring was conducted between 3 September and 7 September 2007. Fauna and flora baseline survey was conducted as follows:

2.3.1 Pak Ngan Heung (PNH) and Luk Tei Tong (LTT) Rivers

According to the Final EM&A Manual, the ecological survey was carried out in each of the 50m long improved sections of the river channels. A total of nine sections were divided for the two rivers (Figure 2-3) which include:

- Two sections for existing upstream of PNH river (i.e. the proposed 80m long trapezoidal channel)

- Two sections for existing downstream of PNH river (i.e. the proposed 100m long rectangular channel)

- Five sections for existing Luk Tei Tong River (i.e. the proposed 240m long trapezoidal channel)

The monitoring parameters and survey methodology for each section are described below:

Avifauna species and densities: Birds in each 50m section were surveyed quantitatively using transect count method. Five minutes were spent in each 50m section. As birds are usually more active in the morning, surveys were carried out early in the morning and completed before 10 a.m. Birds within the boundary of the proposed work areas (i.e. including the river channel and riverbank) were identified to species and their abundance was recorded. Birds flew over/across the proposed work areas without landing were not considered utilising the area and thus excluded from the records. Birds flushed by the surveyor and left the proposed work areas were counted. Nomenclature of birds followed Viney et al. (2005).

Aquatic macroinvertebrate community species composition and abundance: Surveys on aquatic fauna focused on determination of the diversity and abundance of stream aquatic communities. Kick sampling was found not suitable for the surveyed stream sections as either the substrates of the stream bed was sandy (in the PNH upstream), or the flow rate was not sufficient for kick sampling (in the PNH downstream). A twenty-minute search was conducted in each of the 50m section. Sampling methods included active searching, direct observation, and hand netting. In each section, macroinvertebrates were identified and their relative abundance was recorded. All species were released on site once they have been examined and recorded during the survey.

Fish community species composition and abundance: Surveys on fish focused on determination of the diversity and abundance of fish communities. A twenty-minute search was conducted in each of the 50m section. Sampling methods included active searching, direct observation, and hand netting. In each section, fishes were identified and their relative abundance was recorded. All species were released on site once they have been examined and recorded during the survey.

Adult odonate community species composition and abundance: Adult dragonflies in each 50m section were surveyed quantitatively. Twenty minutes were spent in each 50m section. As insects are ectothemic and more active when the ambient temperature is higher (New 1998), surveys were carried out between late morning and mid afternoon (i.e. 10 a.m. – 4 p.m.). Adult dragonflies within the boundary of the proposed work areas (i.e. within the river channel and on the riverbank) were identified to species and their abundance was recorded. Grasses on riverbank provide habitats for damselflies. These microhabitats were searched carefully as damselflies are mostly small in size. As some dragonfly species (e.g., Fiery Emperor Anax immaculifrons, Pale-spotted Emperor Anax guttatus) are strong flyers and seldom perch, dragonflies flew over/across the proposed work areas were also recorded. Species requiring close examination were netted. Nomenclature of dragonfly followed Wilson (2004). All species were released on site once they have been examined and recorded during the survey.

Aquatic, emergent and riparian vegetation community species composition and abundance: Line-intercept method was adopted to determine the relative plant cover. One to two line transects were set perpendicular to the stream channel at each section, and plant intercepting the transect line (including tree and shrub canopy and herbaceous species with intercept more than 1cm) was recorded by species. The two sections in PNH downstream and sections 1 and 5 in LTT river however were channeled with vertical rock gabion and was little vegetated, which forbid quantitative sampling. Transect sampling was therefore conducted at PNH upstream and sections 2 to 4 in LTT river only. The summed transect length represents the sample for each section, and relative plant cover was computed. This will provide an estimate of weighted average cover that is not affected by total transect length. Relative cover of species X = Length of sampled line for species X/Total length of sampled line with vegetation cover * 100. Other than quantitative sampling, walk over surveys were also conducted to record plant species along the stream section. The relative abundance, conservation status of the species and their habitats recorded in Hong Kong as well as the overall summary of vegetation composition was described.

Figure 2-3: Location of stream and marsh sections and quantitative sampling locations for vegetation

Water Quality: The monitoring locations are given in Figure 2-4. The parameters measured include DO, pH, salinity, Biochemical Oxygen Demand (BOD), SS, ammonia, nitrate and phosphate concentrations and water flow. Other physical parameters including monitoring location/position, time, water depth, temperature, weather conditions and any special phenomena were recorded on site. The monitoring methodology for DO, pH, salinity, temperature and SS is described in S.2.2.1 above. The BOD, ammonia, nitrate and phosphate concentrations were analysed in a HOKLAS accredited laboratory and the analyses followed the standard methods according to APHA Standard Methods for the Examination of Water and Wastewater, 19th Edition, or equivalent. The laboratory analytical methods for BOD, ammonia, nitrate and phosphate concentrations are given in Table 2-6 below.

Table 2-6 Laboratory analytical methods

Parameter	Method	Limit of Detection
Nitrate	APHA 4500-NO3:F/NO2:B	0.01 mg/L
Ammonia	APHA 4500 NH3:G	0.01 mg/L
Reactive Phosphorus	APHA 4500 P:F	0.01 mg/L
BOD	APHA 5210B	2 mg/L

Figure 2-4: Location of water quality monitoring stations for ecology

Sediment Characteristics: Sediment samples were also collected by sediment corer or grab sampler at the same locations and the same frequency as the water quality monitoring for ecology described above. One sample was collected in each of the proposed monitoring locations. The samples were stored in clean plastic bag for the subsequent particle size distribution analysis. The collected samples were cooled at 4ºC in the dark and were not frozen. All samples were delivered to the laboratory (Geotechnics & Concrete Engineering (HK) Ltd) within 24 hours of sampling. The analyses followed the standard method according to Geo Spec No 3 - Model Specification for Soil Testing 2001.

2.3.2 LTT Bypass Channel

As stipulated in the Final EM&A Manual, baseline monitoring was conducted along a strip of existing marsh habitat adjacent to the proposed channel alignment (i.e. Reference Site). The ecological surveys were carried out in every 50m section (Figure 2.3).

The LTT marshland was not in a state of stream. Aquatic macroinvertebrate and fish surveys and water quality monitoring for ecology were therefore not able to be conducted. The reference site was divided into six 50m sections. The monitoring parameters and survey methodology for each section are described below:

Avifauna species and densities: Birds in each 50m section were surveyed quantitatively using transect count method. Five minutes were spent in each 50m section. As birds are usually more active in the morning, surveys were carried out early in the morning and completed before 10 a.m. Birds within the Reference Site were identified to species and their abundance was recorded. Birds flew over/across the Reference Site without landing were not considered inhabiting the area and thus were excluded from the records. Birds flushed by the surveyor and left the Reference Site areas were counted. Nomenclature of birds followed Viney et al. (2005).

Adult odonate community species composition and abundance: Adult dragonflies in each 50m section were surveyed quantitatively. Twenty minutes were spent in each 50m section. As insects are ectothemic and more active when the ambient temperature is higher (New 1998), surveys were carried out between late morning and mid afternoon (i.e. 10 a.m. – 4 p.m.). Adult dragonflies within the Reference Site were identified to species and their abundance was recorded. Grasses within the Reference Site provide habitats for damselflies. These microhabitats were searched carefully as damselflies are mostly small in size. As some dragonfly species (e.g., Fiery Emperor Anax immaculifrons, Pale-spotted Emperor Anax guttatus) are strong flyers and seldom perch, dragonflies flew over/across the Reference Site were also recorded. Species requiring close examination were netted. Nomenclature of dragonfly followed Wilson (2004). All species were released on site once they have been examined and recorded during the survey.

Aquatic, emergent and riparian vegetation community species composition and abundance: A 10m line transect was randomly laid in each 50 m section, and six 1m x 1m quadrats were placed regularly along the line transect. Percentage cover of each species within the quadrat was recorded to the nearest 10% (except “1” = present but insignificant cover, normally 1-2 individuals, and 5% = up to 5%). Other parameters were recorded within the quadrat, including average surface water depth to the nearest cm, modal vegetation height judged by eye and measured to the nearest cm. The average percentage cover of each species, average modal height and water depth at each section was computed. Other than quadrat sampling, walk over surveys were also conducted to record plant species. The relative abundance, conservation status of the species and their habitats recorded in Hong Kong as well as the overall summary of vegetation composition was described.

Herpetofauna community species composition and abundance: Herpetofauna surveys within the Reference Site were surveyed qualitatively by active searching in potential habitats. Since most herpetofauna are nocturnal, night surveys were conducted. Twenty minutes were spent in each 50m section. Reptiles were identified and their abundance was recorded. Amphibians were identified by their calls and the number of calling males in each section was recorded. Nomenclature of amphibians followed Chan et al. (2005) and that of reptiles followed Karsen et al. (1998).

2.3.3 Disused Watchtowers in LTT River

The disused watchtowers next to LTT river were checked for the nesting of White-shouldered Starling Sturnus sinensis prior to commencement of the construction works. Surveys were carried out in wet season (i.e. including September). In order to minimize the disturbance to the nesting birds, observations were made at a distance from the watchtowers (> 30m). No attempt was made to go up the watchtowers. The watchtowers were visited in two sessions in a day – morning session and evening session. Each observation session lasted for 30 minutes. Breeding of the White-shouldered Starlings was determined by checking signs of attempt to breed or sign of breeding which include carrying nesting materials, to-and-fro movement of adults carrying food, presence of recently fledged juveniles, etc (Sharrock 1976). The number of breeding pairs and the site observation were recorded whenever possible.

2.4 Cultural Heritage

Baseline survey was carried out to establish the existing condition of the Yuen Compound as stipulated in the Final EM&A report. The Yuen Compound is a privately owned residence established in the 1920s. All of the original buildings are constructed of cut granite blocks quarried from Lai Chi Yuen Hill in Mui Wo. The compound includes 12 main buildings comprising 2 watchtowers, residential buildings and rice storage areas (Figure 2-5).

A field visit was conducted to the Yuen Compound and surrounds. The 12 main buildings identified in the 2003 Built Heritage report were surveyed, reviewed and photographed with respect to their exterior and where possible interior condition, architectural detail and any changes or omission since the 2003 buildings survey. Photographs were taken for record during the survey.

Figure 2-5 Location map of Yuen Compound showing buildings and structures

3 Baseline Monitoring Results

3.1 Noise

3.1.1 Weather Conditions and Other Factors

Noise monitoring was conducted from 9 September to 23 September 2007 for N1 and N3 and from 4/5 October to 19 October 2007 for N2 and N4. The weather was generally sunny and fine during the periods. Major noise sources during the monitoring periods were observed to originate from running stream water, human activities and occasional dog barking.

3.1.2 Summary Results

Noise monitoring results are summarised in Tables 3-1 and 3-2 for different monitoring periods, and details are attached in Appendix 4. Graphical presentations are shown in Figures 3-1 to 3-4.

Table 3-1: Baseline noise monitoring results in non-restricted period

Period	Location	Mean Noise Level, L_{Aeq, 30mins} dB(A)
Daytime (0700-1900 hrs) on normal weekdays	N1	45.3
	N2	52.5
	N3	52.3
	N4	53.2

Table 3-2: Baseline noise monitoring results in restricted period

Period	Location	Mean Noise Level, L_{Aeq, 5mins} dB(A)
Evening time (1900-2300 hrs) on normal weekdays	N1	48.3
	N2	51.3
	N3	52.5
	N4	52.3
Night time (2300-0700 hrs) on normal weekdays	N1	47.4
	N2	47.6
	N3	50.9
	N4	51.4
Sunday & public holiday	N1	46.0
	N2	48.6
	N3	51.4
	N4	52.7

Figure 3-1: Baseline noise monitoring results (mean L_eq(30mins), daytime, normal weekday)

Figure 3-2: Baseline noise monitoring results (mean L_eq(30mins), evening, normal weekday)

Figure 3-3: Baseline noise monitoring results (mean L_eq(30mins), nighttime, normal weekday)

Figure 3-4: Baseline noise monitoring results (mean L_eq(30mins), Sunday and public holiday)

3.2 Water Quality

3.2.1 Weather Conditions and Other Factors

Water quality monitoring was conducted between 20 August and 14 September 2007. The weather was mainly sunny and fine during the period.

3.2.2 Summary Results

The monitoring results are summarised in Tables 3-3 and graphical presentations are shown in Figures 3-5 to 3-7. Details of the monitoring and QA/QC results are attached in Appendix 5. The data in Tables 3-3 are the averaged results from the two duplicated samples at the same depth and same position.

Table 3-3: Baseline water quality monitoring results at ebb tide

Water Quality Monitoring Location	Parameters
M1	6.55 (5.72 - 7.23)	9.45 (3.77 – 17.35)	6.88 (1.50 – 13.00)
M2	6.65 (6.20 – 7.29)	2.75 (1.19 – 6.77)	1.63 (1.00 – 4.50)
M3	6.53 (5.82 – 7.72)	7.14 (2.37 – 28.30)	5.71 (2.50 – 19.00)
M4	6.62 (5.35 – 7.21)	8.64 (4.17 – 18.50)	6.46 (2.00 – 15.50)
C1	6.36 (6.17 – 6.73)	3.69 (1.21 – 7.40)	2.29 (1.00 – 6.50)
C2	6.28 (5.45 – 7.11)	2.19 (1.11 – 4.41)	1.38 (1.00 – 4.00)
C3	6.01 (5.10 – 6.83)	3.31 (1.54 – 8.35)	1.92 (1.00 – 4.50)

Water Quality Monitoring Location

Parameters

Average DO in mg/L

(Range)

Average Turbidity in NTU

(Range)

Average SS in mg/L

(Range)

6.55

(5.72 - 7.23)

9.45

(3.77 – 17.35)

6.88

(1.50 – 13.00)

6.65

(6.20 – 7.29)

2.75

(1.19 – 6.77)

1.63

(1.00 – 4.50)

6.53

(5.82 – 7.72)

7.14

(2.37 – 28.30)

5.71

(2.50 – 19.00)

6.62

(5.35 – 7.21)

8.64

(4.17 – 18.50)

6.46

(2.00 – 15.50)

6.36

(6.17 – 6.73)

3.69

(1.21 – 7.40)

2.29

(1.00 – 6.50)

6.28

(5.45 – 7.11)

2.19

(1.11 – 4.41)

1.38

(1.00 – 4.00)

6.01

(5.10 – 6.83)

3.31

(1.54 – 8.35)

1.92

(1.00 – 4.50)

Figure 3-5: Baseline water quality monitoring results – dissolved oxygen at ebb tide

Figure 3-6: Baseline water quality monitoring results – turbidity at ebb tide

Figure 3-7: Baseline water quality monitoring results – suspended solids at ebb tide

The monitoring results indicated that the DO level was similar in both impact and control stations; while turbidity and SS was in general higher in the impact stations except M2. The tidal effect and possible discharge from agricultural ditch adjacent to the control station are possible influencing factors to the monitoring results at downstream and upstream C1 during/after rainstorm, respectively.

3.3 Ecology

3.3.1 Luk Tei Tong Marsh Reference Site

3.3.1.1 Vegetation

A total of 33 species was recorded within quadrats along the 6 sections of the reference site. The marsh was fairly heterogeneous in terms of species composition. Only Mikania micrantha was recorded at all sections; while most of the other species were only recorded in one or two sections. Average cover of vegetation varied from 145.0% to 188.2%, indicating mild to moderate overlap of canopy of species, for example, Mikania overgrown on other plants, or grasses and herbs grown under broadleaved species (Table 3-4). Average modal height of vegetation ranged from 60.6cm to 100.4cm. During the survey, the substrate of the reference site was soft and saturated from Section 1 to Section 3 and standing water was recorded at the Colocasia field, while Section 4 to Section 6 were relatively dry.

A total of 64 species was recorded at and around the reference section (Appendix 6). Forty-seven were native while 17 were exotics. They are mainly composed of grasses, remnants of commercial crops, exotics or pantropical weeds. The marsh was wet agricultural field grown with Colocasia esculenta (yam) and Hedychium coronarium (ginger flower) and was abandoned for probably more than 20 years. The remnants of these crops were still seen in “wetter” part of the marsh. Some native pioneer tree and shrub species as well as exotic landscape trees established within the marsh as tree stands or isolated individuals within the site. No species recorded are protected under local regulations or known to be of conservation interest in Hong Kong. According to the approved EIA and findings from the previous site visit during dry season of 2005 and the present baseline survey, both the impacted area (i.e. the proposed LTT bypass channel) and the reference site represented the relatively drier portion of the whole Luk Tei Tong Marsh.

Table 3-4: Percentage cover and modal height of vegetation at the reference site of Luk Tei Tong Marsh

Species	Total Percentage Cover
Species	Section 1	Section 2	Section 3	Section 4	Section 5*	Section 6
Ageratum conyzoides					46.0	0.2
Apluda mutica			30.0
Colocasia esculenta		26.0	46.0
Commelina diffusa	10.2	68.0	0.4
Conyza canadensis						2.0
Cyclosorus interruptus			5.2
Cyperus imbricatus				3.0
Echinochloa crusgalli	6.0
Eupatorium catarium	0.4
Fimbristylis sp.				13.0	1.0	0.3
Hedychium coronarium			1.0	2.0	31.2
Hedyotis diffusa				0.2
Hydrocotyle sibthorpioides				1.6
Ipomoea cairica					9.0
Isachne globosa	15.2			34.0
Kyllinga brevifolia					0.2
Lindernia cordifolia				0.2
Ludwigia octovalvis	35.0			13.0
Microstegium ciliatum					14.0	68.0
Mikania micrantha	19.0	68.0	64.0	17.0	7.0	1.0
Panicum maximum						10.0
Panicum repens						0.2
Paspalum conjugatum	10.0			<

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Parameters	Monitoring locations
	M1		M2		M3		M4
	Action Level	Limit Level	Action Level	Limit Level	Action Level	Limit Level	Action Level	Limit Level
DO (mg/L)	5.7	4	6.2	4	5.9	4	5.9	4
SS (mg/L) ^{[1, 2]}	12.2	12.8	3.1	4.2	12.4	17.7	13.9	15.2
Tby (NTU) ^{[1, 2]}	15.2	16.9	5.3	6.5	16.8	26.0	16.2	18.0