To support the increased use of natural gas in Hong Kong from 2020 onwards, Castle Peak Power Company Limited (CAPCO) and The Hongkong Electric Co., Ltd. (HK Electric) have identified that the development of an offshore liquefied natural gas (LNG) receiving terminal in Hong Kong using Floating Storage and Regasification Unit (FSRU) technology (‘the Hong Kong Offshore LNG Terminal Project’) presents a viable additional gas supply option that will provide energy security through access to competitive gas supplies from world markets. The Hong Kong Offshore LNG Terminal Project will involve the construction and operation of an offshore LNG import facility to be located in the southern waters of Hong Kong, a double berth jetty, and subsea pipelines that connect to the gas receiving stations (GRS) at the Black Point Power Station (BPPS) and the Lamma Power Station (LPS).

The Environmental Impact Assessment (EIA) Report for the Hong Kong Offshore LNG Terminal Project was submitted to the Environmental Protection Department (EPD) of the Hong Kong Special Administrative Region Government in May 2018. The EIA Report (EIAO Register No. AEIAR-218/2018) was approved by EPD and the associated Environmental Permit (EP) (EP-558/2018) was issued in October 2018. An application for Further Environmental Permits (FEP) was made on 24 December 2019 to demarcate the works between the different parties. The following FEPs were issued on 17 January 2020 and the EP under EP-558/2018 was surrendered on 5 March 2020:

§ the double berth jetty at LNG Terminal under the Hong Kong LNG Terminal Limited, joint venture between CAPCO and HK Electric (FEP-01/558/2018/A) ([1]);

§ the subsea gas pipeline for the BPPS and the associated GRS in the BPPS under CAPCO (FEP-03/558/2018/A) ([2]); and

§ the subsea gas pipeline for the LPS and the associated GRS in the LPS under HK Electric (FEP-02/558/2018/A)([3]).

The location plan for the works associated with the subsea gas pipeline for BPPS and the associated GRS in BPPS (‘the Project’) is provided in Figure 1.1.

1.2 Objectives of the Silt Curtain Deployment Plan

This Silt Curtain Deployment Plan for the Project has been prepared in accordance with Condition 2.10 of the Further Environmental Permit FEP-03/558/2018/A.

FEP No. FEP-03/558/2018/A, Condition 2.10:

“The Permit Holder shall, no later than 1 month before the commencement of marine works including construction of the subsea gas pipeline, deposit with the Director 3 hard copies and 1 electronic copy of a silt curtain deployment plan. The silt curtain deployment plan shall include but not limited to the details of the design, installation, testing, operation and maintenance of the silt curtains to be deployed during construction of the Project to avoid and minimize the water quality impact due to the dredging and jetting works for laying and burying the subsea gas pipeline. Pilot tests on the efficiency of silt curtain system shall be conducted during the early stage of construction to confirm the removal efficiency of the silt curtains. The deposited silt curtain deployment plan shall be fully and properly implemented during construction of the Project.”

The key objective of this Silt Curtain Deployment Plan is to include the details of the design, installation, testing, operation and maintenance of the silt curtains to be deployed during construction of the Project to avoid and minimize the water quality impact due to the dredging and jetting works for laying and burying the subsea gas pipeline.

The Silt Curtain Deployment Plan will be reviewed and updated as appropriate, throughout the course of the construction works to confirm that it remains current with the latest detailed information and works practice.

1.3 Overview of Silt Curtain Deployment

As stipulated in Condition 3.3 of FEP-03/558/2018/A, silt curtains shall be properly installed, tested, operated and maintained during construction of the subsea gas pipeline in accordance with the Silt Curtain Deployment Plan deposited under Condition 2.10 of FEP-03/558/2018/A. Cage-type silt curtain shall be installed enclosing the grab dredger and jetting machine during construction of the subsea gas pipeline. No silt curtain installation shall encroach onto the existing marine parks, especially the Sha Chau and Lung Kwu Chau Marine Park and the Southwest Lantau Marine Park, and the proposed South Lantau Marine Park.

Two types of silt curtains will be deployed for the dredging and jetting works as well as cofferdam construction and removal at the pipeline landfall of BPPS of the Project:

§ Cage-type silt curtain will be installed enclosing the grab dredger / jetting machine during dredging / jetting works for the construction of the subsea gas pipeline; and

§ Floating double layer silt curtain will be deployed prior to the jetting works at KP0.1 - KP8.9, KP31.5 - KP41.1, KP42.9 – KP44.9, dredging works at KP44.9 – KP 45.0 and works areas for cofferdam construction and removal at the pipeline landfall of BPPS in order to minimize potential water quality impacts in the areas including south of the proposed South Lantau Marine Park, west and northwest of Sha Chau and Lung Kwu Chau Marine Park, and the water sensitive receivers for coral colonies at artificial seawall at BPPS. Specific locations requiring the deployment of floating double layer silt curtains are illustrated in Figure 1.2 and the silt curtain arrangement during construction of the cofferdam for BPPS Pipeline is illustrated in Figure 1.3.

2. Design of Silt Curtains

2.1 Cage-type Silt Curtain

Cage-type silt curtain will be installed for dredging and jetting activities for the pipeline construction works. A cage-type silt curtain consists of a layer of geotextile tied on a steel pipe surface buoyancy frame with pipe diameter of ~1,000 mm. The geotextile will be secured from water surface to seabed level by steel chain ballast. Sufficient length of the geotextile will be provided such that the silt curtain can be extended from the water surface to the seabed level during high tide condition. Silt curtain with various curtain depth and curtain strength of 110 kN/m ([4]) will be deployed. The bottom part of the silt curtain will be kept away from the seabed by a distance of ~0.3m in order to avoid disturbing the seabed. The indicative design of cage-type silt curtain is illustrated in Figure 2.1 and the typical arrangement of cage-type silt curtain installed for a grab dredger barge is illustrated in Figure 2.2.

Figure 2.1 Cage-type Silt Curtain Indicative Design

77cbebdc141b4e38b71d25e9501fc55

Remark: The shape and dimension of the cage-type silt curtain are indicative and subject to modification depending on site conditions.

Figure 2.2 Typical Arrangement of Cage-type Silt Curtain

2.2 Floating Silt Curtain

Floating silt curtain will be deployed in the vicinity of the proposed South Lantau Marine Park (KP0.1-8.9), Sha Chau and Lung Kwu Chau Marine Park (KP31.5-41.1) and the water sensitive receivers for coral colonies at artificial seawall at BPPS (KP42.9-45.0). No silt curtain installation will encroach onto the existing and proposed marine parks.

The floating silt curtain consists of two layers of geotextile mounted onto polystyrene foam float with diameter of ~500 mm with polyethylene protective hard shell cover. The geotextile will be extended slightly above the seabed level and secured by steel chain ballast or equivalent (e.g. concrete sinkers) to avoid the bottom part of the silt curtain from touching the seabed and causing unnecessary disturbance of seabed sediment. The bottom part of the silt curtain will be kept away from the seabed by a distance of ~0.3m in order to avoid disturbing the seabed.

The length of the silt curtain deployed at the active dredging / jetting location will be determined considering the findings of the EIA Report and Environmental Review Report for the BPPS Pipeline Construction Options, the potential impact to existing marine traffic for review by the Marine Department and the performance of the pilot test (see details in Section 4) upon agreement with the Environmental Team and the Independent Environmental Checker. Surface structure of the floating silt curtain will be linked to a towing rope instead of being towed by motor tugs direct for manoeuvring in order to reduce the tension of the floating silt curtain during towing. Flashlight will be installed on marker buoys and tug boats for alerting marine operators at night. Should the floating silt curtain be necessary to be separated into sections for mitigating the impacts to marine traffic, a distance of ~150 m overlapping between two sections of the floating silt curtain will be maintained as far as practicable. The floating silt curtain will be shifted during jetting depending on the location of jetting operation. Should there be any unacceptable water quality impacts to the water sensitive receivers at Sha Chau and Lung Kwu Chau Marine Park, the proposed South Lantau Marine Park and the coral colonies at artificial seawall at the BPPS from the impact water quality monitoring, the Contractor(s) will propose remediation measures (e.g. checking of silt curtain integrity, extension of floating silt curtain) in consultation with the ET and the IEC.

Floating silt curtain for the cofferdam construction and removal at pipeline landfall will be deployed at the locations as indicated in Figure 1.2 where the two ends of the floating silt curtain will be attached to the artificial seawall at BPPS / end of cofferdam such that the works area of the cofferdam construction and removal will be enclosed by the floating silt curtain. Sufficient length of the geotextile will be provided such that the silt curtain can be extended from the water surface to the seabed level during high tide condition. The bottom part of the silt curtain will be kept away from the seabed by a distance of ~0.3m in order to minimise disturbance to the seabed.

The indicative arrangement for floating silt curtain in the vicinity of the marine park / coral colonies at artificial seawall at BPPS is illustrated in Figure 2.3. The indicative arrangement for floating silt curtain in sections is illustrated in Figure 2.4. The specification of the proposed geotextile is shown in Table 2.1. The details of manufacturer / supplier’s specifications and project references are shown in Annex D.

Figure 2.3 Indicative Arrangement of Floating Silt Curtain

Notes:

1) Preliminary 1000m length, subject to site conditions and trial.

2) Distance between silt curtain and metal frame will be subject to site condition and trial.

3) Similar floating silt curtain arrangement will be adopted for the coral colonies at artificial seawall at BPPS. The floating silt curtain will be deployed at the seaward side of the coral colonies parallel to the artificial seawall for mitigating potential water quality impacts to the coral colonies at artificial seawall at BPPS.

Figure 2.4 Indicative Arrangement of Double Layer Silt Curtain in Sections

Table 2.1 Specification of the Proposed Geotextile

*Technical Data Sheet*
Polymer	Density	Melting Point		Construction
100% Polypropylene	0.91 kg/dm³	165 °C		Tapes
*Properties*
Mechanical Properties	Standard	Performance		Tolerance
Tensile strength - MD	EN ISO10319	110 kN/m		-9.9 kN/m
Tensile strength - CMD	EN ISO10319	110 kN/m		-9.9 kN/m
Elongation at maximum load - MD	EN ISO10319	10 %		+/- 2.3 %
Elongation at maximum load - CMD	EN ISO10319	8 %		+/- 1.8 %
Static puncture resistance (CBR)	EN ISO12236	12.5 kN		-2.5 kN
Dynamic perforation resistance (cone drop)	EN ISO13433	10 mm		+2.0 mm
Tensile strength at 2% elongation - MD	EN ISO10319	15 kN/m
Tensile strength at 2% elongation - CMD	EN ISO10319	25 kN/m
Tensile strength at 5% elongation - MD	EN ISO10319	45 kN/m
Tensile strength at 5% elongation - CMD	EN ISO10319	60 kN/m
Hydraulic Properties	Standard	Performance		Tolerance
Water permeability normal to the plane (Vlh50)	EN ISO11058	25 l/m²s		-8 l/m²s
Characteristic Opening Size (O90)	EN ISO12956	230 µm		+/- 69.0 µm
Physical Properties	Standard	Performance		Tolerance
Weight	EN ISO9864	464 g/m²		+/- 46.4 g/m²
Length (+/- 1%) x width (+/- 1%)	-	100 x 5.25 m		-
Truck Load Volume (+/- 10%)	-	30,450 m²		-
Roll diameter (+/- 10%)	-	45 cm		-
Durability	Standard		Performance
Predicted minimal durability in years in natural soils with 4 <pH < 9 and soil temperature <25°C	EN ISO13438 - A2		25 years
Maximum allowed time between installation and covering of the geosynthetic	EN 12224		2 weeks
Remarks: Having considered the maximum current speeds of construction operation (i.e. 1.74 m/s for top layer while 1.37 m/s for bottom layer), water depth and seawater density of the BPPS Pipeline, the curtain strength of 110 kN/m is selected which is strong enough to withstand the current speed conditions such that efficiency reduction of silt curtain is not expected. No marine construction works will be carried out if the current exceeds the maximum current speeds of construction operation (i.e. 1.74 m/s for top layer while 1.37 m/s for bottom layer).

3. Installation of Silt Curtains

3.1 Cage-type Silt Curtain

Cage-type silt curtain will be fixed and hung underneath the frame by nylon rope on deck of crane barge after the completion of fabrication of steel buoyancy frame. The skirt of cage-type silt curtain will be coiled by tightening rope for easy deployment.

The entire steel buoyancy frame with cage-type silt curtain will be lifted and erected to the grab dredger or jetting machine when the rigging structure or mounting brace is ready. The coiling ropes will be cut at the steel buoyancy frame and the curtain skirt will be released to the seabed for enclosure.

Cable ropes pre-installed at the bottom of the cage-type silt curtain will be lifted up and tightened at the steel buoyancy frame to adjust the depth of curtain skirt on site from time to time.

3.2 Floating Silt Curtain

Floating silt curtain will be delivered to the location for fixing by flat top/crane barge. All vertical joints of each span of the floating silt curtain will be connected and tied up and coiled with ropes in a tube-form pattern by workers working on deck of the barge.

Steel chain ballast or equivalent (e.g. concrete sinkers) will be deployed at the designated positions along the route by crane barge equipped with real-time global positioning system when the position of floating silt curtain is confirmed.

One of the ends of the towing rope will be picked up and the floating silt curtain will be lowered down slowly into the water by the main towage front tug when the floating silt curtain is available for deployment.

Coiling rope will be cut by small work boat, and the curtain skirt and ballast chain will be released into the water after the other end of towing rope is secured at the back tug and all tugs are in position.

3.3 Works Activities requiring Deployment of Silt Curtains

The works activities (i.e. dredging / jetting works) requiring deployment of silt curtains in the corresponding locations are shown in Table 3.1.

Table 3.1 Locations of Deployment of Silt Curtain

Work Location	Cage-type Silt Curtain	Floating Silt Curtain
Pipeline Riser (BPPS KP0.0-0.1)	Yes	No
BPPS Pipeline
Jetty Approach, including Subsea Cable Sterile Corridors (BPPS KP0.1 – 5.0)	Yes	Yes (at Southern Boundary of the Proposed South Lantau Marine Park), except for grab dredging works at Subsea Cable Sterile Corridors
South of Soko Islands (BPPS KP5.0 – 8.9)	Yes	Yes (at Southern Boundary of the Proposed South Lantau Marine Park)
Southwest of Soko Islands (BPPS KP8.9 – 12.1)	Yes	No
Adamasta Channel (BPPS KP12.1 – 15.6)	Yes	No
Southwest Lantau (BPPS KP15.6 – 21.3)	Yes	No
West of Tai O to West of HKIA (BPPS KP21.3 – 31.5)	Yes	No
Sha Chau to Lung Kwu Chau (BPPS KP31.5 – 36.0)	Yes	Yes (at Western Boundary of the Sha Chau and Lung Kwu Chau Marine Park)
Sha Chau to Lung Kwu Chau (BPPS KP36.0 – 37.5)	Yes	Yes (at Western Boundary of the Sha Chau and Lung Kwu Chau Marine Park)
Lung Kwu Chau to Urmston Anchorage (BPPS KP37.5 – 41.1)	Yes	Yes (at NW corner of Sha Chau and Lung Kwu Chau Marine Park)
Urmston Road (BPPS KP41.1 – 42.9)	Yes	No
West of BPPS (BPPS KP42.9 – 44.9)	Yes	Yes (at CR1 and CR2) ^{(Note 1)}
Pipeline shore approach at BPPS (BPPS KP44.9 – 45.0)	Yes	Yes (at CR1 and CR2)^{(Note 1)}
Note: (1) CR1 and CR2 denote the coral colonies identified at the artificial seawall at BPPS.

4. Testing of Silt Curtains

4.1 Background of the Pilot Test

As stated in Condition 2.10 of FEP-03/558/2018/A and Section 5.3.2 of the Updated EM&A Manual of the Hong Kong Offshore LNG Terminal Project, pilot tests on the efficiency of silt curtain system shall be conducted during the early stage of construction to confirm the removal efficiency of the silt curtains. The pilot test will be conducted by measuring turbidity and suspended solids (SS) at selected stations within and outside silt curtains to be discussed below.

The pilot test on silt curtain systems will include the following tests:

§ Silt curtain at grab dredger (testing of silt removal efficiency of 75% or higher);

§ Silt curtain at jetting machine (testing of silt removal efficiency of 85% or higher); and

§ Double layer of silt curtains at sensitive receivers (testing of silt removal efficiency of 80% or higher).

The results of the pilot tests to be conducted during the early stage of construction will be applicable to dredging / jetting works for the Hong Kong Offshore LNG Terminal Project, i.e. the subsea gas pipeline for BPPS under FEP-03/558/2018/A and the subsea gas pipeline for LPS under FEP-02/558/2018/A.

4.2 Arrangement of the Pilot Test

During the pilot test, dredging/ jetting works shall be actively undertaken within the works areas with the silt curtains deployed, and shall be operated at or close to the maximum productivity. The surrounding environment will be controlled as far as practicable such that there would be no other major construction activities with potential of generating suspended solids being operated concurrently.

4.2.1 Locations of Pilot Test

The pilot test covers two different types of silt curtains proposed, the cage-type silt curtain and the floating silt curtain.

4.2.1.1 Cage-type Silt Curtain during Dredging and Jetting

There will be five monitoring stations of which one will be inside the cage while the rest will be outside the silt curtain in four directions. The indicative monitoring locations for cage-type silt curtain during dredging and jetting are shown in Table 4.1 and Figure 4.1.

Table 4.1 Indicative Monitoring Locations for Cage-type Silt Curtain during Dredging and Jetting

Monitoring Station	Location	Description
A1	Within silt curtain	One monitoring station will be located inside the cage
B1	Outside silt curtain	Four monitoring stations will be located at four sides of silt curtain and within ~50 m from the silt curtain boundary
B2
B3
B4

Remark: Each applicable station will be sampled and measurements/ water samples will be taken at three depths, 1m below the sea surface, mid-depth and 1m above the seabed. For stations that are less than 3m in depth, only the mid-depth sample shall be taken. For stations that are less than 6m in depth, only the sea surface and bottom samples shall be taken. For in-situ measurements, duplicate readings shall be made at each water depth at each station. Duplicate water samples shall be collected at each water depth at each station.

Figure 4.1 Indicative Monitoring Locations for Cage-type Silt Curtain during Dredging and Jetting

Note: The actual monitoring locations will be determined on site considering the locations of the cage-type silt curtain, anchor wires of the barges and nearby marine traffic conditions.

4.2.1.2 Floating Silt Curtain

There will be six monitoring stations of which three will be near the marine works area while the rest will be at the other side of the silt curtain. As the floating silt curtain will be placed at water sensitive receivers, the distance between the emission source and the silt curtain for the pilot test is expected to be ranged from ~20m to ~100m depending on the location where the pilot test will be conducted in the vicinity of water sensitive receivers (e.g. the proposed South Lantau Marine Park). The indicative monitoring locations for floating silt curtain are shown in Table 4.2 and Figure 4.2.

Table 4.2 Indicative Monitoring Locations for Floating Silt Curtain

Monitoring Station	Location	Description
A1	Near marine works area	Three monitoring stations will be ~50 m apart from each other and situated between marine works area and the silt curtain boundary
A2
A3
B1	The other side of silt curtain	Three monitoring stations will be ~50 m apart from each other and situated at ~50 m from the other side of silt curtain boundary
B2
B3

Remarks:

1) Each applicable station will be sampled and measurements/ water samples will be taken at three depths, 1m below the sea surface, mid-depth and 1m above the seabed. For stations that are less than 3m in depth, only the mid-depth sample shall be taken. For stations that are less than 6m in depth, only the sea surface and bottom samples shall be taken. For in-situ measurements, duplicate readings shall be made at each water depth at each station. Duplicate water samples shall be collected at each water depth at each station.

2) Measurements/ water samples will be taken at representative tidal condition during which the direction of water currents will be from marine works area towards silt curtain.

Figure 4.2 Indicative Monitoring Locations for Floating Silt Curtain

Note 1: The distance will depend on the location where the pilot test will be conducted in the vicinity of water sensitive receivers.

4.2.2 Testing Parameters for Pilot Test

The testing parameters for the pilot test are shown in Table 4.3. Other relevant data will also be measured and recorded during the pilot test, including the location of the monitoring stations, water depth, time, weather conditions, sea conditions, tidal state, current direction and velocity, special phenomena and dredging / jetting rate during the pilot test. The monitoring equipment to be used, sampling / testing protocols, laboratory measurement and analysis will follow the requirements as stated in the Updated EM&A Manual.

Table 4.3 Testing Parameters and Equipment for Pilot Test

Parameter	Unit	Abbr.	Standard Methods	Detection Limit
In-situ measurements
Turbidity	NTU	-	Instrumental, CTD	0.1
Laboratory measurements
Suspended solids	mg L^-1	SS	APHA 2540E	1.0

4.2.3 Timing and Duration

The pilot test will be scheduled to be conducted during the early stage of construction:

§ three rounds within a single monitoring day covering mid-ebb and mid-flood tides for cage-type silt curtain for dredging works. Each round of monitoring will be conducted when dredging works are operated at or close to the maximum productivity and the measurement at each monitoring station between any two rounds will be separated by at least 1 hour. The monitoring will be scheduled when relatively high current speed condition is expected on the day of testing, as far as practicable;

§ three rounds within a single monitoring day covering mid-ebb and mid-flood tides for cage-type silt curtain for jetting works. Each round of monitoring will be conducted when jetting works are operated at or close to the maximum productivity and the measurement at each monitoring station between any two rounds will be separated by at least 1 hour. The monitoring will be scheduled when the relatively high current speed condition is expected on the day of testing, as far as practicable; and

§ three rounds within a single monitoring day for floating silt curtain. Each round of monitoring will be conducted when jetting works are operated at or closed to the maximum productivity and the measurement at each monitoring station between any two rounds will be separated by at least 1 hour. The monitoring will be scheduled when the representative tide with relatively high current speed condition is expected on the day of testing, as far as practicable. Measurements/ water samples will be taken at representative tidal condition during which the direction of water currents will be from marine works area towards silt curtain for the pilot test for floating silt curtain.

Given the monitoring design of the pilot test is to measure near-field water quality around the emission source to determine the silt-retaining effectiveness of the silt curtain system, the proposed pilot test monitoring frequency (i.e. three rounds within a single monitoring day when relatively high current speed condition is expected on the day of testing and during representative tide with relatively high current speed condition which the direction of water currents will be from marine works area towards floating silt curtain to represent worst case scenario for the silt curtain system in terms of the silt-retaining capacity and integrity) is considered adequate.

During the pilot test, the dredging / jetting works shall be actively conducted within the works areas at a representative work rate not exceeding the allowed maximum work rate as stated in the Updated EM&A Manual. The surrounding environment should be controlled as far as practicable such that there would be no other major SS-generating construction activity operating concurrently in the vicinity that may influence the pilot test results.

4.2.4 Reporting

Considering that the pilot test will be conducted during the early stage of construction, the findings of the pilot test will be reported in the corresponding monthly EM&A report for the month in which the pilot test would be conducted, and the following information will be reported:

§ Location plan(s) showing the monitoring stations for the corresponding silt curtains;

§ Results of in-situ and laboratory measurement (in summary and full dataset); and

§ Findings from the evaluation of pilot test results and recommendations for improvements, if any.

4.3 Determination of Silt Curtain Efficiency

Silt curtain efficiency is determined by the difference between the SS level ([5]) near marine works area and that outside silt curtain. The following equation is adopted to determine silt curtain efficiency:

where, SS (inside) is determined by averaging the SS levels inside the marine works area (e.g. the average of A1 to A3 for floating silt curtain); SS (outside) is determined by averaging the SS levels at monitoring stations outside the silt curtains (i.e., the average of B1 to B3 for floating silt curtain; the average of B1 to B4 for cage-type silt curtain).

Should the efficiency of the silt curtain system to be adopted did not satisfy the requirements in the approved EIA Report, the Contractor shall propose further measures / improvements to the silt curtain system for consideration by CAPCO, the ET and the IEC. However, regardless of the measured efficiency of the silt curtain system, the Event and Action Plan established in the Updated EM&A Manual shall only be based on the monitoring results of the construction phase water quality monitoring at the impact monitoring stations.

5. Operation and Maintenance of silt curtain

The Contractor will check the condition of the silt curtain (both cage type and floating silt curtain) before commencement of works every day. Refuse around the silt curtains will be collected regularly and as needed on a daily basis so that water behind the silt curtains will be kept free from floating debris. Sufficient spare geotextile will be kept on site for replacing damaged silt curtains. The spare geotextile shall be kept appropriately to avoid direct contact with water and sunlight.

Underwater silt curtain inspection will be carried out after adverse weather (e.g. Typhoon Signal No. 3 or above). Underwater silt curtain inspection will also be conducted after installation / re-installation / relocation of silt curtains / suspected sediment release due to ineffectiveness of silt curtain (e.g. from the impact water quality monitoring results to be conducted by the ET, observations by the Contractor(s), CAPCO, ET or IEC). Underwater silt curtain inspections shall cover at least a 10m length of silt curtain or one whole silt curtain panel (whichever is greater) at each location, and at intervals of at least every 200m along the length of silt curtains deployed. The underwater inspections shall check that the silt curtain fabric is intact, the silt curtain depths and ballast weight (for cage-type silt curtain) and steel chain ballast or equivalent (e.g. concrete sinker) (for floating silt curtain) positions are correct, and there is no damage / breakage in ballast weights/ steel chain ballast or equivalent and load lines. Photographic records shall be taken during each underwater inspection. All identified defects / damage shall be photographed and the position recorded on GPS to enable the affected areas to be subsequently located for in-situ repair where appropriate. An inspection checklist will be prepared and filled in by the Contractor, and endorsed by CAPCO. All checklists will be kept on site for record purpose.

In the event of silt curtain being damaged and/or requiring repairing works at the corresponding works locations, the related dredging / jetting works will be suspended immediately until the rectification works for the silt curtain is completed subject to the satisfaction by CAPCO.

Samples of Silt Curtain Daily Inspection Checklist and Underwater Inspection Checklist are shown in Annex A and Annex B, respectively.

([1]) Application for variation of an environmental permit for FEP-01/558/2018 was undertaken and the latest FEP (FEP-01/558/2018/A) was issued on 6 November 2020.

([2]) Application for variation of an environmental permit for FEP-03/558/2018 was undertaken and the latest FEP (FEP-03/558/2018/A) was issued on 22 January 2021.

([3]) Application for variation of an environmental permit for FEP-02/558/2018 was undertaken and the latest FEP (FEP-02/558/2018/A) was issued on 22 December 2020.

([4]) Having considered the maximum current speeds of construction operation (i.e. 1.74 m/s for top layer while 1.37 m/s for bottom layer), water depth and seawater density of the BPPS Pipeline, the curtain strength of 110 kN/m is selected which is strong enough to withstand the current speed conditions such that efficiency reduction of silt curtain is not expected. No marine construction works will be carried out if the current exceeds the maximum current speeds of construction operation (i.e. 1.74 m/s for top layer while 1.37 m/s for bottom layer).

([5]) Turbidity may also be used to determine silt curtain efficiency as necessary.