Further Environmental Permit No.FEP-13/004/1999
新 的 環 境 許 可 證 編 號 FEP-13/004/1999

ENVIRONMENTAL IMPACT ASSESSMENT ORDINANCE
(CHAPTER 499)
SECTION 12

環 境 影 響 評 估 條 例
(第 499章)
第 12條

FURTHER ENVIRONMENTAL PERMIT TO CONSTRUCT A PART OF THE
DESIGNATED PROJECT
就 建 造 指 定 工 程 項 目 其 中 部 分 而 發 出 新 的 環 境 許 可 證

PART A (MAIN PERMIT)
A部 (許 可 證 主 要 部 分)

Pursuant to section 12 of the Environmental Impact Assessment Ordinance, the Director of Environmental Protection (the Director) grants this Further Environmental Permit to Penta-Ocean - Kier Joint Venture (the "Permit Holder") to construct a part of the designated project described in Part B subject to the conditions described in or attached to Part C. The issue of this Further Environmental Permit is based on the documents, approvals or permissions described below:

根 據 環 境 影 響 評 估 條 例 第 12條 的 規 定 , 環 境 保 護 署 署 長 (署 長)將 本 新 的 環 境 許 可 證 批 予 Penta-Ocean - Kier Joint Venture (許 可 證 持 有 人) 以 建 造 B部 所 說 明 的 指 定 工 程 項 目 其 中 部 分 , 但 須 遵 守 C部 所 說 明 或 附 載 的 條 件 。 本 新 的 環 境 許 可 證 的 發 出 , 乃 以 下 表 所 列 的 文 件 、 批 准 或 許 可 作 為 根 據 :

Application No.
申 請 書 編 號
FEP-016/1999
Documents in the Register :
登 記 冊 上 的 文 件 :

(1) Environmental Permit
West Rail - Phase 1 (Register No. EP-004/1998)
環 境 許 可 證
西 鐵 第 一 期
(登 記 冊 檔 號 : EP-004/1998)

(2) EIA report
West Rail - Final Assessment Report West Kowloon to Tuen Mun Centre - Environmental Impact Assessment, its Technical Annexes, and Final Landscape Design Strategy, Report Vol.1 (Register No. EIA-149/1998) [Hereafter referred to as the EIA report]
環 評 報 告
西 鐵 - 最 終 評 估 報 告 西 九 龍 至 屯 門 中 心 - 環 境 影 響 評 估 、 其 技 術 附 件 及 最 終 景 觀 美 化 設 計 策 略 報 告 第 一 冊 (登 記 冊 檔 號 : EIA-149/1998)
[下 稱 環 評 報 告]

(3) Environmental Monitoring and Audit Manual
West Rail - Environmental Monitoring and Audit Manual West Kowloon to Tuen Mun Centre - Environmental Impact Assessment
(Submitted in accordance with condition 2.18 of the Environmental Permit No. EP-004/1998) [Hereafter referred to as the EM&A Manual]
環 境 監 察 及 審 核 手 冊
西 鐵 - 環 境 監 察 及 審 核 手 冊 西 九 龍 至 屯 門 市 中 心 - 環 境 影 響 評 估
(根 據 環 境 許 可 證 EP-004/1998 第 2.18項 條 件 提 交 )



___________________
Date
日 期


______________________________________
(Elvis W.K. AU)
Assistant Director of Environmental Protection
for Director of Environmental Protection
環 境 保 護 署 署 長
(環 境 保 護 署 助 理 署 長 區 偉 光 代 行)

PART B (DESCRIPTION OF THE PART OF THE DESIGNATED PROJECT)
B部 (指 定 工 程 項 目 本 部 分 的 說 明 )

Hereunder is the description of the part of the designated project mentioned in Part A of this further environmental permit :-

下 列 為 本 新 的 環 境 許 可 證 A部 所 提 述 的 指 定 工 程 項 目 本 部 分 的 說 明 : -

Title of the Part of the Designated Project
指 定 工 程 項 目 本 部 分 的 名 稱
Kowloon - Canton Railway Corporation - West Rail Phase 1 Contract No. CC300 - Tsuen Wan Station and Approach Tunnels
[This part of the designated project is hereafter referred to as "the Project"]

九 廣 鐵 路 公 司 - 西 鐵 第 一 期
合 約 編 號 CC300 - 荃 灣 站 及 接 駁 隧 道

[指 定 工 程 項 目 本 部 分 下 稱 「 工 程 項 目 」]

Nature of the part of the Designated Project
指 定 工 程 項 目 本 部 分 的 性 質
Construction of Tsuen Wan Station and Approach Tunnels

建 造 荃 灣 站 及 接 駁 隧 道

Location of the Part of the Designated Project
指 定 工 程 項 目 本 部 分 的 地 點
The location of the project is shown in Figure 1 of this Further Environmental Permit
工 程 項 目 的 地 點 載 於 新 的 環 境 許 可 證 的 圖 1
Scale and Scope of the Part of the Designated Project
指 定 工 程 項 目 本 部 分 的 規 模 和 範 圍
The project involves the following works:

a) Construction of the underground two level, three track Tsuen Wan West Station partly in the new Tsuen Wan reclamation and partly on previously reclaimed land.

b) Construction of the Northern Approach Tunnels as shown in Figure 1.

c) Construction of the Southern Approach Tunnels as shown in Figure 1.

d) External Works and Ancillary Structures include:

1. Completion of the structure of the cooling water pumping station for Tsuen Wan West Station including all fitting out works.

2. Major stormwater culverts diversions for the following:

- Tai Ho Culvert (including car park access ramp);

- Ma Tau Pa Culvert.

本 工 程 項 目 涉 及 下 列 工 程 :

a) 在 地 下 建 造 兩 層 、 三 軌 的 荃 灣 西 站 , 該 車 站 部 分 位 於 新 的 荃 灣 填 海 區 , 部 分 則 位 於 以 前 完 成 的 填 海 土 地 。

b) 建 造 如 圖 1顯 示 的 北 面 接 駁 隧 道 。

c) 建 造 如 圖 1顯 示 的 南 面 接 駁 隧 道 。

d) 戶 外 工 程 及 附 屬 的 構 築 物 包 括 :

1. 完 成 荃 灣 西 站 冷 卻 水 抽 水 站 的 構 築 物 , 包 括 各 項 裝 修 工 程 。

2. 以 下 地 點 的 主 要 雨 水 下 水 道 改 道 工 程 :

- 大 河 下 水 道 ( 包 括 停 車 場 的 斜 道 ) ;

- 馬 頭 壩 下 水 道 。

PART C (PERMIT CONDITIONS)

1. General Conditions

1.1 The Permit Holder shall ensure full compliance with all conditions of this Further Environmental Permit (the Permit). Any non-compliance with this Permit may constitute a contravention of the Environmental Impact Assessment Ordinance (Cap. 499) and shall be definite ground for enforcement action or permit cancellation where applicable.

1.2 This Permit shall not remove the responsibility of the Permit Holder to comply with any legislation currently in force such as Noise Control Ordinance (Cap. 400), Air Pollution Control Ordinance (Cap. 311), Water Pollution Control Ordinance (Cap. 358), Dumping at Sea Ordinance (Cap. 466), the Waste Disposal Ordinance (Cap. 354) and others.

1.3 The Permit Holder shall make copies of this Permit available at all times for inspection by the Director at all sites covered by this Permit.

1.4 The Permit Holder shall give a copy of this Permit to the person(s) in charge of the site(s).

1.5 The Permit Holder shall display a copy of this Permit on the construction site(s) at all vehicular site entrances/exits for public information at all times. The Permit Holder shall ensure that the most updated information about the environmental permit, including any amended permit, is displayed at such locations. If the Permit Holder surrenders a part or the whole of the Permit, the notice he sends to the Director of Environmental Protection shall also be displayed at the same locations as the original Permit.

1.6 A copy of the EIA Report and a copy of the Environmental Permit EP-004/1998 or any subsequent variation approved by the Director under the Environmental Impact Assessment Ordinance, shall be kept in the Engineer's (as set out in EM&A Manual) office and another copy shall be kept in the Permit Holder's office on site for reference.

1.7 The Permit Holder shall construct the Project in accordance with the project descriptions in Part B of this Permit.

1.8 The Permit Holder shall ensure that the Project is designed and constructed in accordance with the information and recommendations contained in the EIA report and in the Environmental Permit No. EP-004/1998 or any subsequent variation approved by the Director under the Environmental Impact Assessment Ordinance.

1.9 This Permit shall not remove the responsibility of any person to comply with the conditions set out in Part C of the Environmental Permit No. EP-004/1998 or any subsequent variation approved by the Director under the Environmental Impact Assessment Ordinance.

1.10 Amendments to approved or deposited submissions required under this Permit shall be verified by the Independent Environmental Checker as conforming to the information and recommendations contained in the EIA report and in the Environmental Permit No. EP-004/1998 or any subsequent variation approved by the Director under the Environmental Impact Assessment Ordinance. Amendments to approved submissions shall be approved by the Director and amendments to deposited submissions shall be deposited with the Director.

1.11 The requirements of Environmental Manager and Independent Environmental Checker, as required under this Permit, are described in conditions 2.1 and 2.2 of the Environmental Permit No. EP-004/1998 or any subsequent variation approved by the Director under the Environmental Impact Assessment Ordinance.

1.12 Approved plans, schedules, reports, drawings or programmes mentioned in this Permit shall refer to those that have been approved by the Director.

1.13 All deposited submissions, as required under this permit, shall be rectified in accordance with the comments, if any, made by the Director within one month of the receipt of the Director's comments or otherwise specified by the Director.

1.14 All finalised submissions, as required under this permit, shall be released to the public if requested by the Director, by depositing copies in the Environmental Impact Assessment Ordinance Register Office or any other places or by any other means as specified by the Director for public inspection. For this purpose, the Permit Holder shall provide sufficient copies of submissions.

1.15 The Permit Holder shall notify the Director one week prior to the commencement of construction of the project works.

2. Submissions or Measures before Commencement of Construction of Certain Sections of the Project

2.1 An Environmental Team as recommended in the EM&A Manual shall be in place prior to the commencement of construction of the Project, described in Part B of this Permit. The Environmental Team shall be headed by a team leader who has at least 7 years experience in environmental monitoring or environmental management.

2.2 Before the commencement of construction of the Project described in Part B of this Permit, 3 sets of 1 to 1000 scale layout drawing shall be made available to and deposited with the Director. The layout drawings shall include an explanatory statement showing the works boundary, railway and tunnel alignment, environmental mitigation measures recommended in the EIA report and in the Environmental Permit No. EP-004/1998 or any subsequent variation approved by the Director under the Environmental Impact Assessment Ordinance, and any other facilities assessed in the EIA report and in the Environmental Permit No. EP-004/1998 or any subsequent variation approved by the Director under the Environmental Impact Assessment Ordinance. The drawings shall be certified by the Environmental Manager and verified by the Independent Environmental Checker as conforming to the findings and recommendations of the EIA report and in the Environmental Permit No. EP-004/1998 or any subsequent variation approved by the Director under the Environmental Impact Assessment Ordinance. The Project shall be constructed in accordance with the information and recommendations contained in the EIA report and in the Environmental Permit No. EP-004/1998 or any subsequent variation approved by the Director under the Environmental Impact Assessment Ordinance and the drawings deposited with the Director. All measures set out in the drawings shall be fully implemented. (see note 6)

2.3 The Permit Holder shall make available to the Director for approval three sets of landscape master plan(s) 1 to 1000 scale together with a master implementation schedule before the commencement of construction of relevant sections of the Project described in Part B of this Permit. The drawings shall be expanded based on the Landscape Strategy Report of the EIA report and in the Environmental Permit No. EP-004/1998 or any subsequent variation approved by the Director under the Environmental Impact Assessment Ordinance and shall show the conceptual landscape proposals within the works boundary to be in accordance with the recommendations of the EIA report and in the Environmental Permit No. EP-004/1998 or any subsequent variation approved by the Director under the Environmental Impact Assessment Ordinance during the construction and operation of the Project. It shall also include a management and maintenance schedule indicating clearly how the landscape areas will be managed and maintained. The landscape drawings shall be certified by the Environmental Manager, and verified by the Independent Environmental Checker. All measures recommended in the approved drawings shall be fully implemented in accordance with the details and time schedule set out in the approved landscape master plan(s). (see note 7)

2.4 Three sets of detailed landscape drawings shall be made available to the Director for approval before the commencement of landscape and visual mitigation works of the relevant section(s) of the Project or part(s) thereof. Such drawings shall expand on the approved landscape master plan(s) and shall show the detailed landscape proposals during the construction and operation of the Project. The landscape drawings shall be certified by the Environmental Manager, and verified by the Independent Environmental Checker. All measures recommended in the approved drawings shall be fully implemented in accordance with the details and time schedule set out in the approved landscape drawings. (see note 8)

2.5 Before the commencement of the construction of the Project, the Permit Holder shall submit and obtain the approval of the Director Contamination Assessment Plans (CAP) of the potentially contaminated sites in accordance with the information and recommendations contained in the EIA report and in the Environmental Permit No. EP-004/1998 or any subsequent variation approved by the Director under the Environmental Impact Assessment Ordinance and Annex 19, Section 13 of the Technical Memorandum on EIA Process (TM). Before submission to the Director, the CAP shall be certified by the Environmental Manager and verified by the Independent Environmental Checker.

2.6 Before the commencement of the construction of the Project, the Permit Holder shall submit and obtain the approval of the Director Contamination Assessment Reports (CAR) based on the endorsed CAP in accordance with Annex 19, Section of the TM. During the preparation of the CAP, if land contamination is confirmed, Remediation Action Plans (RAP) are required in accordance with Annex 19, Section 3 of the TM and shall be make available as a combined report with the CAR to the Director for approval. Before submission to the Director, the results of the CAR and any RAP shall be certified by the Environmental Manager and verified by the Independent Environmental Checker. All measures recommended in the approved RAP shall be fully implemented in accordance with the requirements and time schedule set out in the approved RAP.

2.7 Before the commencement of construction, the Permit Holder shall deposit with the Director waste management plan(s) as recommended in the EIA report and in the Environmental Permit No. EP-004/1998 or any subsequent variation approved by the Director under the Environmental Impact Assessment Ordinance. Before submission to the Director, the waste management plan(s) shall be certified by the Environmental Manager and verified by the Independent Environmental Checker. Measures covered by the Waste Disposal Ordinance shall not be included in the wastes management plan(s). All measures recommended in the deposited waste management plan or any subsequent amendments shall be fully implemented in accordance with the requirements and time schedule(s) set out in the waste management plan.

3. Submissions or Measures during the Construction Period

3.1 Within two months of commencement of construction of the Project described in Part B of this Permit, an environmental management plan as recommended in the EIA report and in the Environmental Permit No. EP-004/1998 or any subsequent variation approved by the Director under the Environmental Impact Assessment Ordinance shall be deposited with the Director. Before its submission to the Director, the environmental management plan shall be certified by the Environmental Manager and verified by the Independent Environmental Checker as conforming to the information and recommendations of the EIA report and in the Environmental Permit No. EP-004/1998 or any subsequent variation approved by the Director under the Environmental Impact Assessment Ordinance.

3.2 The Permit Holder shall fully implement all design or construction measures described in the approved or deposited submissions mentioned in section 2 and condition 3.1 above. Any changes to these design and construction measures shall be justified by Environmental Manager and verified by the Independent Environmental Checker as conforming to the information and recommendations contained in the EIA report and in the Environmental Permit No. EP-004/1998 or any subsequent variation approved by the Director under the Environmental Impact Assessment Ordinance.

3.3 The Permit Holder shall implement measures described in Appendix A to mitigate environmental impacts from site run-off and drainage.

3.4 In accordance with the information and recommendations contained in the EIA report and in the Environmental Permit No. EP-004/1998 or any subsequent variation approved by the Director under the Environmental Impact Assessment Ordinance and with reference to Annex B, measures to mitigate water quality impacts during tunneling and station construction shall be implemented.

3.5 To mitigate the cultural heritage and archaeological impacts during construction, the Permit Holder shall inform the Director immediately if any antiquities are discovered during the course of the construction works to further assess the cultural value of the items.

4. Environmental Monitoring and Audit During Construction

4.1 The Permit Holder shall keep a copy of the EM&A Manual, as described in Part A of this Permit, at his office on site for reference.

4.2 Any changes to the EM&A arrangements, including all methodologies and criteria, monitoring equipment, monitoring locations, baseline monitoring, impact monitoring, compliance assessment and event contingency plan, as required under the EM&A Manual or under the Implementation Schedule, shall be justified by the Environmental Manager, and verified by the Independent Environmental Checker in the monthly EM&A Reports and submitted to the Director under condition 4.6.

4.3 The EM&A requirements shall be implemented, including all methodologies and criteria, monitoring equipment, monitoring locations, baseline monitoring, impact monitoring, compliance assessment and event contingency plans, as set out in the EM&A Manuals and monthly EM&A Reports, unless the changes are justified in the monthly EM&A Reports submission, verified by the Independent Environmental Checker and approved by the Director.

4.4 Samples and measurements shall be taken in accordance with the requirements of noise, air quality and water quality monitoring in the EM&A Manual by:

(a) conducting baseline air and noise quality monitoring at the specified locations and frequencies;

(b) conducting impact monitoring on air and noise quality at the specified locations and frequencies;

(c) in cases where specified criteria in the EM&A Manual are exceeded, carrying out remedial actions in accordance with event contingency plans, to be set out in the EM&A Manual; and

(d) logging and keeping records of the details of (a) to (c) above, within 3 working days of the collection of data or completion of remedial action, for the purposes of preparing and submitting EM&A Reports, and to make available for information for inspection on site.

4.5 Four copies of the Baseline Monitoring Report certified by the Environmental Manager, and verified by the Independent Environmental Checker shall be made available to the Director one month before the commencement of any major construction works that would affect the monitoring results.

4.6 Four copies of monthly EM&A Reports certified by the Environmental Manager, and verified by the Independent Environmental Checker shall be made available to the Director within 10 working days from the end of the reporting month.

4.7 Actions described in the action plan(s) / contingency plan(s) of the EM&A Manual shall be properly carried out, in accordance with the time frame set out in the action plan(s) / contingency plan(s), or as agreed by the Director.

5 Submission on Measures before Operation of the Project

5.1 All design or operational measures relevant to the Project described in the submission approved, or deposited under section 2 and section 3, shall be fully implemented.

5.2 Upon completion of the construction of the Project, an audit shall be carried out to confirm that all the agreed environmental measures for the construction of the Project have been properly implemented. The audit shall cover all measures recommended in the EIA report and in the Environmental Permit No. EP-004/1998 or any subsequent variation approved by the Director under the Environmental Impact Assessment Ordinance, or described in approved or deposited submissions. The result of the audit shall be documented in an Audit Report certified by the Environmental Manager and verified by the Independent Environmental Checker to the information and recommendations contained in the EIA report and in the Environmental Permit No. EP-004/1998 or any subsequent variation approved by the Director under the Environmental Impact Assessment Ordinance prior to submission to the Director.

5.3 Five sets of the as-built drawings of scale 1 to 1000 with an explanatory statement showing the works and mitigation measures covered by this Permit, shall be deposited with the Director within three months after the completion of the construction of the Project.

Notes:

1. This Environmental Permit consists of three parts, namely, PART A (Main Permit), PART B (Description of the Part of Designated Project) and part C (Permit Conditions).

2. The Permit Holder may apply under section 13 of the Environmental Impact Assessment Ordinance to the Director for a variation of the conditions of this Environmental Permit. The Permit Holder shall replace the original Permit displayed on the construction site, by the amended Permit.

3. A person who assumes the responsibility for the whole or a part of the Project may, before he assumes responsibility of the Project, apply under section 12 of the Ordinance to the Director for a further Environmental Permit.

4. Under section 14 of the Ordinance, the Director with the consent of the Secretary for Planning, Environment and Lands, may suspend, vary or cancel this Permit. The Permit shall then be removed from the display on the construction site.

5. If this Permit is cancelled or surrendered during the construction, an Environmental Permit must be obtained under the Ordinance before the construction of the Project could be continued. It is an offence under section 26(1) of the Ordinance to construct or operate a designated project without an Environmental Permit.

6. Kowloon Canton Railway Corporation (Holder of Environmental Permit No. EP-004/1998) is required under condition 2.4 of the Permit No. EP-004/1998 to submit the 1 to 1000 scale layout drawing required in condition 2.2 of this Permit.

7. Kowloon Canton Railway Corporation (Holder of Environmental Permit No. EP-004/1998) is required under condition 2.7 of the Permit No. EP-004/1998 to submit the 1 to 1000 scale landscape master plan(s) required in condition 2.3 of this Permit.

8. Kowloon Canton Railway Corporation (Holder of Environmental Permit No. EP-004/1998) is required under condition 2.8 of the Permit No. EP-004/1998 to submit the detailed landscape drawings required in condition 2.4 of this Permit.

9. All submission as required under this Permit shall be deposited in the Environmental Impact Assessment Ordinance Register Office on 27/F of Southorn Centre, 130 Hennessy Road, Wanchai, Hong Kong.

Appendix A

Measures to Mitigate Environmental Impacts from Site Run-off and Drainage

To mitigate the environmental impacts from site run-off and drainage, the following shall be implemented:

(a) adequate maintenance of drainage systems shall be provided to prevent flooding and overflow during the construction period;

(b) the boundaries of areas of earthworks shall be marked and surrounded by dykes for flood protection during the construction period. Temporary ditches should be provided to facilitate runoff discharge into the appropriate watercourses, via a silt retention pond. Permanent drainage channels should incorporate sediment basins or traps and baffles to enhance deposition rates. The design of efficient silt removal facilities should be based on the guidelines in ProPEC Practice Note 1/94 issued by the Director of Environmental Protection;

(c) construction works shall be programmed to minimize surface excavation works during the rainy season (April to September). All exposed earth shall be stabilized as soon as possible after earthworks have been completed, or alternatively, within 14 days of the cessation of earthworks where practicable. If excavation of soil cannot be avoided during the rainy season, or at any time of year when rainstorms are likely, exposed slope surfaces should be covered by tarpaulin or other means;

(d) sediment tanks of sufficient capacity constructed from pre-formed individual cells of approximately 6 to 8 cu.m. capacity shall be used for settling surface runoff prior to disposal during the construction period. The system capacity shall be flexible and able to handle multiple inputs from a variety of sources and particularly suited to applications where the influent is pumped;

(e) open stockpiles of construction materials (e.g. aggregates, sand and fill material) of more than 50 cu.m. shall be covered with tarpaulin or similar fabric during rainstorms. Measures should be taken to prevent the washing away of construction materials, soil, silt or debris into any drainage system;

(f) manholes, including newly constructed ones, shall always be covered and sealed so as to prevent silt, construction materials or debris being washed into the drainage system and storm runoff being directed into foul sewers during the construction period. At any time of year when rainstorms are imminent or forecast, actions shall be taken in accordance with the ProPECC Practice Note 1/94 issued by the Director of Environmental Protection. Particular attention should be paid to the control of silty surface runoff during storm events, especially for areas located near steep slopes;

(g) oil interceptors shall be provided in drainage systems and oils and grease shall be regularly removed to prevent the release of oils and grease into storm water drainage systems after accidental spillage during the construction period. The interceptors should have a bypass to prevent flushing during periods of heavy rain;

(h) all vehicles and plant shall be cleaned before leaving a construction site to ensure no earth, mud, debris and the like is deposited by them on roads during the construction period. An adequately designed and located wheel washing bay should be provided at every site exit and wash-water should have sand and silt settled out and removed at least on a weekly basis to ensure the continued efficiency of the process. The section of access road leading to, and exiting from, the wheel-wash bay to the public road should be paved with sufficient backfill toward the wheel-wash bay to prevent vehicle tracking of soil and silty water to public roads and drains;

(i) sediment shall be intercepted before it enters into modified sections of culverts. Sediment traps should be installed both upstream and downstream of any modified culvert sections in order to minimise the sediment loading in these culverts. Vortex tube site traps shall also be installed to provide continuous extraction of sediment within the modified sections of the culverts;

(j) temporary and permanent drainage pipes and culverts shall be provided to facilitate runoff discharge during the construction period. The temporary and permanent drainage pipes and culverts should be adequately designed for the controlled release of storm flows. All sediment control measures should be regularly inspected and maintained to ensure proper and efficient operation at all times and particularly following rain storms. Temporarily diverted drainage should be reinstated to its original condition when construction work has finished or the temporary diversion is no longer required; and

(k) discharge and surface runoff contaminated by materials from any concrete batching plant shall be diverted to neutralisation tank to reduce acidity and the treated discharge should be connected to silt trap to remove suspended solids before disposing to sewage system.

Appendix B

Measures to Mitigate the Water Quality Impacts During Tunneling and Station Construction

To mitigate the water quality impacts during tunneling and station construction:

(a) cut-and-cover tunnel work shall be conducted segment by segment to limit the amount of construction runoff generated in the areas during the wet season (April to September). Temporary open storage of excavated materials used for backfill on site should be covered with tarpaulin or similar fabric during rainstorms. Any washout of construction or excavated materials should be diverted through appropriate sediment traps before discharge to stormwater drainage system. Ground water pumped out of tunnels should be discharged into the drainage channels which incorporate sediment traps to enhance deposition rates and to remove silt; and

(b) spent bentonite slurries or other grouts used in diaphragm wall construction and in a separate slurry collection system shall be collected, and reconditioned and reused wherever practicable.


Figure 1


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