1.
INTRODUCTION
1.1.1
The Territorial Land Drainage
and Flood Control Strategy Study – Phase II (TELAFLOCOSS 2), completed in
August 1993, recommended as part of its findings that detailed studies were
required to resolve secondary and local stormwater drainage problems in five
drainage basins in the North and
1.1.2 The YLDMP started in January 1996 and was completed in December 1996. The Study was to examine and assess the secondary and local drainage systems, recommend prompt, short and long term improvement measures to resolve the identified problems, and develop a prioritized program for implementation of the recommended improvement works.
1.1.3 The YLDMP has identified problems in the existing drainage systems in the study area and has recommended drainage improvement proposals under a two-stage implementation program. The Stage 1 works (i.e. this Project - Yuen Long, Kam Tin, Ngau Tam Mei & Tin Shui Wai Drainage Improvement Stage 1) are to be implemented under this Assignment for mitigating major drainage problems requiring immediate attention.
1.1.4
Black & Veatch Hong Kong
Limited (B&V HKL) (formerly Binnie Black & Veatch Hong Kong Limited)
was commissioned on 26 July 1999 by the Employer, Drainage Services
Department (DSD), to carry out the preliminary and detailed design and
construction supervision of the Yuen Long, Kam Tin, Ngau Tam Mei & Tin Shui
Wai Drainage Improvement, Stage 1 Project. This Stage 1 Assignment
commenced on
1.2
Yuen Long, Kam Tin, Ngau Tam Mei & Tin Shui Wai Drainage
Improvement, Stage 1
1.2.1 Stage 1 of Yuen Long, Kam Tin, Ngau Tam Mei and Tin Shui Wai Drainage Improvement comprises the construction of works as shown in Figure 1.1. In order to expedite the drainage improvement works in the urban areas, Stage 1 works are divided into two phases, namely Phase 1 and Phase 2, encompassing the following principal elements:
(a) Phase 1 – Bank Raising and Urban Drainage Improvements in Tin Shui Wai and Yuen Long Areas
(i)
Bank raising of about 2.5 km of
primary channels (Ha Tsuen and Hung Shui Kiu Channels) and associated
modification works including the replacement of railings by parapet wall,
re-provision/modification of affected bridges and re-provision of local drains
for affected areas in the
(ii) Construction of about 6.4 km of replacement/relief drains, associated manholes and lateral connections in Hung Shui Kiu, Ping Shan, and Yuen Long town areas.
These works in Phase 1, under
Contract No. DC/2000/06, are not Designated Projects (DP) as defined under the
EIA Ordinance. The Environmental Study (ES) Report for Phase 1 works [Ref.
382047/E/ES/Issue 2, dated September 2001] was submitted to the Government. The
PWSC paper for Phase 1 works was endorsed in June 2001, and the construction of
Phase 1 works commenced on
(b) Phase 2 – Construction of Secondary Drainage Channels
(i) Construction of about 7.5 km of secondary channels and associated maintenance accesses including re-provision of vehicular and pedestrian crossings, drainage and utility diversion works, associated road furniture and lighting facilities, landscaping and other ancillary works at the following areas:
(a)
NTM1 – the total length of the
proposed channel is about 400 m including a 90 m long box culvert. It comprises
a rectangular concrete channel of 2.5 m width and 2 m height and a box culvert
of 2.5 m width and 2 m height at downstream, connecting to an existing twin box
culvert under
(b) KT2 – the preliminary alignment generally follows the existing stream course. The total length of this channel is about 1320 m. The channel comprises three sections. The upstream section is a rectangular channel of 6m width and 3m height. The middle section is a trapezoidal channel of 6 m width at the base and 3 m height. The downstream section, a rectangular channel of 8 m width and 3 m height, avoids affecting the Agriculture, Fisheries and Conservation Department’s Au Tau Fisheries Office. The downstream end of the channel will join the trained Kam Tin River Channel.
(c) KT4 – the preliminary alignment generally follows the existing stream course. The total length of this channel is about 600 m. The preliminary design is a trapezoidal channel of 5 m width at the base and 2.5 m height. The downstream end of the channel will join the Kam Tin North River Channel to be constructed under Contract No. DC/98/04 – Construction of Main Drainage Channels for Yuen Long and Kam Tin, Stage II, Kam Tin San Tsuen to Wang Toi Shan Section (Contract D).
(d) KT5 – the preliminary alignment generally follows the existing stream course. The total length of the channel is about 840 m. For 70 m upstream, the channel is rectangular, of 4 m width and 2 m height. The rest of the channel is trapezoidal, of 5m width at the base and 2.5 m height. The downstream end of the channel will join the Kam Tin North River Channel to be constructed under Contract No. DC/98/04 – Construction of Main Drainage Channels for Yuen Long and Kam Tin, Stage II, Kam Tin San Tsuen to Wang Toi Shan Section (Contract D).
(e) KT6 – the preliminary alignment generally follows the existing stream course. The total length of the channel is about 600 m. The preliminary design is a trapezoidal channel of 5 m width at the base and 2 m height. The downstream end of the channel will join the Kam Tin North River Channel to be constructed under Contract No. DC/98/04 – Construction of Main Drainage Channels for Yuen Long and Kam Tin, Stage II, Kam Tin San Tsuen to Wang Toi Shan Section (Contract D).
(f) KT7 – the preliminary alignment generally follows the existing stream course. The total length of the channel is about 730 m. The preliminary design is a trapezoidal channel of 3.5 m width at the base and 2 m height. The downstream end of the channel will join the Kam Tin North River Channel to be constructed under Contract No. DC/98/04 – Construction of Main Drainage Channels for Yuen Long and Kam Tin, Stage II, Kam Tin San Tsuen to Wang Toi Shan Section (Contract D).
(g)
KT12 - the preliminary
alignment generally follows the existing stream course. The total length of the
channel is about 200 m. The preliminary design is a trapezoidal channel of 3.5
m width at the base and 2 m height. The downstream end will match with Box
Culvert No. 4 constructed by the
(h) KT13 - this is the Designated Project (DP) which is subject of this EIA. Section 2 gives a detailed description of the existing environmental elements of works proposal for secondary drainage channel KT13.
(i) KT14 – the proposed channel comprises four local drainage channels with preliminary dimensions as below:
Section A – 2.5 m width and 2.8 m height, 145 m
Section B – 2.5 m width and 1.6 m height, 339 m
Section C – 2.5 m width and 1.6 m height, 474 m
Drain along
Bank raising along the existing
toe channel of
The downstream end of the channels will be connected to an open channel constructed by KCRC – West Rail.
(j) KT15 - the preliminary alignment generally follows the existing stream course. The total length of the channel is about 796 m. The preliminary section design varies from a trapezoidal channel of 6.7 m – 9.9 m width at the base and 1.6 m height to a rectangular channel of 3.5 m width and 1.6 m height.
An Environmental Study has been carried out to review the potential impacts and environmental opportunities and requirements for those secondary channels. Secondary drainage channel KT13 is a DP under the definition of the Environmental Impact Assessments Ordinance (EIAO), and is the subject of this EIA. Secondary drainage channels KT14 and KT15 are also DPs under definitions of the EIAO. A separate Project Profile has been undertaken on KT14 and KT15 to identify environmental protection requirements for these secondary drainage channels in order to obtain the Environmental Permit for construction by direct application.
1.3
Secondary Drainage Channel KT13
1.3.1 This EIA is prepared for the proposed works under the secondary drainage channel KT13 only, which is a Designated Project (DP) as defined under the Environmental Impact Assessment (EIA) Ordinance pursuant to the following categories of Schedule 2 Part I of the Ordinance as shown below.
|
Category under Schedule
2 Part I of the EIA Ordinance |
Description |
|
Item I.1 (b)(vii) |
The channel discharges
into an area which is less than 300m from the nearest boundary of an existing
conservation area. |
|
Item Q.1 |
A section of the channel
(bypass culvert) encroaches an existing conservation area. |