9
hazARd to life review
9.1
Yau Kom Tau Water Treatment Works (YKTWTW)
9.1.1
The YKTWTW is located approximately
1km to the west of Tsuen Wan and is situated on a level platform cut into the
hillside immediately above Tuen Mun Road. To the east and southwest of the YKTWTW, there lie high rise
residential developments including Greenview Terrace, Greenview Court, One
Kowloon Peak, Bayview Garden, Belvedere Garden, Hanley Villa, Sunny Villa,
Grandview Villa, etc. The YKTWTW is located approximately 800m to the west of
the Project site (refer to Figure 9.1).
9.1.3
In accordance with Appendix H
of the EIA Study Brief (ESB-343/2021), Hazard to Life assessment is required to
evaluate potential hazard associated with the storage, use and on-site
transport of liquid chlorine at the YKTWTW during construction and operation
phases of the Project. According to the latest PHI register, YKTWTW has been
delisted and no longer considered as PHI. No hazard to life assessment for
liquid chlorine related issue is required for YKWTW.
9.2.1
The OSCG plants generate
chlorine gas on demand by using electrolysis technology. The process uses salt
and water to generate chlorine gas and sodium hypochlorite, with hydrogen gas
as a by-product.
9.2.2
The major hazards associated
with operation of the OSCG plants include:
·
Failures associated with the
chlorine system pipework; and
·
Hydrogen gas leak from pipes
and flanges before vented to outdoor area
9.2.3
Highways Department (HyD) subsequently took over the project from CEDD. HyD’s traffic review study on TWR traffic conditions
conducted in 2016 revealed that the widening of TWR and improvement of
associated junctions were needed to cope with the future traffic demand.
9.2.4
With reference to the Hazard to
Life assessment conducted in approved EIA for Agreement No. CE 69/2001(HY)
Tsuen Wan Bypass, Widening of Tsuen Wan Road between Tsuen Tsing Interchange
and Kwai Tsing Interchange and Associated Junction Improvement Works
(Register No.: AEIAR-124/2008), the failure of chlorine system pipework was
represented by gas leakage from 4.5mm hole, resulted in 0.027 kg/s release to
atmosphere under normal ventilation and 0.011 kg/s release under “door left
open” situation. Both releases will not result in off-site hazard.
9.2.5
In case of hydrogen gas leak
within the chlorine store, the hydrogen gas will be mixed with air to
concentration lower than its Lower Flammable Limit (LFL), i.e. 4%, and vented
outside the chlorine store at the roof top level of the chlorine store. No
off-site risks are thus anticipated.