1. Executive summary

1.1 This Baseline Water Quality Monitoring Report was prepared by Cinotech Consultants Ltd. for the Drainage Services Department’s (DSD) Contract No. DC/2009/10 “HATS 2A –Upgrading works at Stonecutters Island Treatment Works – Main Pumping, Sedimentation Tanks and Ancillary Facilities”. This report presents the baseline water quality monitoring works performed for the Project from September 2017 to February 2018.

1.2 The baseline water quality monitoring was conducted at 58 designated monitoring stations, at a frequency of one day per month in a six month period. The monitoring was conducted for a total of 6 days at mid-ebb and mid-flood tides to monitor the parameters including temperature dissolved oxygen, dissolved oxygen saturation, turbidity, salinity and E. coli.

1.3 During the baseline monitoring period, no marine construction works, temporary sewage bypassing and other observable pollution source were identified in the vicinity of the monitoring stations. The baseline water quality data established in this report are considered to be representative of the baseline conditions.

1.4 The baseline data were processed, reviewed and analysed to categorise the sampled data. The Action and Limit Levels for dissolved oxygen, turbidity and E. coli are derived for impact monitoring (Tables 4.6a, 4.6b, 4.7, 4.8a and 4.8b).