Off-site Chlorine Risk Assessment from Shum Shui Kwok Dock to ...

Appendix 12.11

Off-site Chlorine Risk

Assessment from Shum

Shui Kwok Dock to

STWTW

ERM-HONG KONG, LTD WSD

A12.11-1

A12.11-1 INTRODUCTION

This Appendix provides supplementary information to Section 12.25 of the

Main Report. The total risk associated with transport of chlorine from Shum

Shui Dock to STWTW has been assessed as a reference and the results are

compared to the Hong Kong Risk Guidelines (HKRG), which applies to fixed

installation in general. The assessment methodology and assumptions are

provided in the Main Report and will not be repeated in this Appendix.

A12.11-1.1 OFF-SITE TRANSPORT RISK RESULTS FOR CHLORINE DELIVERY FROM SHUM SHUI

KWOK DOCK TO STWTW

FN curves for off-site chlorine transport risk during the Construction and

Operational Phases of are shown in Figure 1.1. The off-site chlorine transport

risk is higher during the Operational Phase compared to that during the

Construction Phase. It is mainly due to the higher chlorine delivery quantities

(761 tonnes versus 642 tonnes). The FN curves are in the upper ALARP region.

The fatalities at frequency of 10-9 per year are about 900 for both Construction

and Operational Phases. This is lower than the 1000 fatality criterion as per

HKRG.

It should be noted that transport societal risk is generally presented as per one

kilometre. Summation of societal risk along the route could result in over-

estimation of risk. Nevertheless, the current risk level remains within the

ALARP region.

ERM-HONG KONG, LTD WSD

A12.11-2

Figure 1.1 FN Curves for Off-site Chlorine Transport from SSK Dock to STWTW

ERM-HONG KONG, LTD WSD

A12.11-3

The individual risk (IR) from SSK Dock to STWTW is shown in Figure 1.2.

Only the Operational Phase IR is shown as this is the worst case due to higher

quantity of chlorine delivery. As can be seen, the individual risk levels are

well below the Hong Kong Risk Guidelines criterion of 10-5 per year. The IR

spreads along both sides of the routes and reduces rapidly to below the 10-7

per year.

Figure 1.2 Individual Risk for Off-site Chlorine Transport from SSK Dock to STWTW

10-7

per year