Agreement No. CE
23/2012 (EP)
Environmental Monitoring and Audit
for Contaminated Mud Pits at the South of The Brothers and at East
Sha Chau (2012-2017) - Investigation
7TH
MONTHLY PROGRESS REPORT FOR MARCH 2013
1.1.1
Since early 1990s, contaminated
sediment ([1]) arising from
various construction works in Hong
Kong has been disposed of at a series of seabed
pits at East of Sha Chau (ESC). In
late 2008, a review indicated that the existing and planned facilities at ESC
would not be able to meet the disposal demand after 2012. In order to meet this demand, the Hong
Kong Special Administrative Region Government (HKSARG) decided to implement a
new contained aquatic disposal (CAD) ([2])
facility at the South of The Brothers (SB CMPs) (hereafter referred to
as “the Project”) which had been under consideration for a number of years.
1.1.2
The environmental acceptability of the
construction and operation of the Project had been confirmed by findings of the
associated Environmental Impact Assessment (EIA) study completed in 2005 under Agreement No. CE
12/2002(EP) ([3]).
The Director of Environmental Protection (DEP) approved this EIA report
under the Environmental
Impact Assessment Ordinance (Cap. 499) (EIAO) in
September 2005 (EIA Register No.: AEIAR-089/2005).
1.1.3
In accordance with the EIA
recommendation, prior to commencement of construction works for the SB CMPs,
the Civil Engineering and Development Department (CEDD) undertook a detailed
review and update of the EIA findings for the SB site ([4]). Findings of the EIA review undertaken in
2009/ 2010 confirmed that the construction and operation of the SB site had
been predicted to be environmentally acceptable.
1.1.4
An Environmental Permit (EP-427/2011) was
issued by the Environmental Protection Department (EPD) to the CEDD, the Permit
Holder, on 3 November 2011 and varied on 23 December 2011 (EP-427/2011/A). Under the requirements of Condition 4 of
the EP (EP-427/2011/A), an
Environmental Monitoring and Audit (EM&A) programme as set out in the
EM&A Manual () is
required to be implemented for the SB CMPs. The present EM&A programme
undertaken under Agreement No. CE 23/2012 (EP) covers the dredging, disposal and
capping operations of the SB CMPs.
1.2
Reporting Period
1.2.1
This Monthly Progress Report covers the
EM&A activities for the reporting month of March 2013.
1.3
Details of Sampling and Laboratory Testing Activities
1.3.1
Impact Water Quality Monitoring
during Dredging Operations of CMP 1 was
conducted three times per week (ie 2, 4, 6, 8, 11, 13, 15, 18, 20, 22, 25, 27
and 29 March 2013) in this reporting month in accordance with the EM&A
Manual.
1.4.1
No outstanding sampling remained from March 2013. Laboratory analysis of Suspended Solids
(SS) collected after 25 March 2013 was still in progress during the preparation
of this monthly report. A summary
of field activities conducted are presented in Annex A.
1.5.1
Monitoring data
collected for SB CMPs from 26 February to 25 March 2013 are presented in this
monthly report. Detailed discussion
will be presented in the corresponding Quarterly
Report.
1.5.2
Impact Water Quality Monitoring during Dredging
Operations of CMP 1 – February and March 2013
1.5.3
Impact Water Quality Monitoring
during Dredging Operations of CMP 1 was
conducted three times per week with a total of thirteen (13) sampling days from
26 February to 25 March 2013. On
each survey day, sampling was conducted during both mid-ebb and mid-flood tides
at two Reference (Upstream) stations upstream and five Impact (Downstream)
stations downstream of the dredging operations at CMP 1. Monitoring was also conducted at five
Sensitive Receiver Stations (Ma Wan, Shum Shui Kok, Tai Mo To and Tai Ho
Bay). A total of twelve stations
were monitored and locations of the sampling stations are shown in Figure 1.1.
1.5.4
Monitoring
results from 26 February to 25 March 2013 are presented in Table
B1 of Annex B. Levels of
Dissolved Oxygen (DO), Turbidity and SS generally complied with the Action and
Limit Levels (see Table B2 for
details) set in the Baseline Monitoring Report (), except during mid-flood tide on 26, 28 February 2013.
1.5.5
Action Level
exceedances of Turbidity and SS were recorded during mid-flood tide at Impact
station DS1, on 26 and 28 February 2013, respectively.
1.5.6
Station DS1 is
located in close proximity to the works area of CMP 1 (ie within 500m from the
works area). Since the exceedances
were recorded at station DS1 and during one tidal period only, it is considered
that the sediment plume was transient in nature and limited to the close
vicinity of the works area as predicted in the EIA review of the Project ([7]). Hence, the
dredging works did not appear to cause any unacceptable deterioration in water
quality. It should also be noted
that high levels of SS and Turbidity were occasionally recorded during baseline
monitoring which are considered to be sporadic events and characteristic of
water quality in this area of Hong Kong.
As such, the exceedances recorded may also be caused by natural
background variation in water quality of the area.
1.5.7
Overall, the
results indicated that the dredging operations at CMP 1 of SB did not appear to
cause any unacceptable deterioration in water quality during this reporting
period. Therefore, no further
mitigation measures, except for those recommended in the Environmental Permit (EP-427/2011/A), are considered necessary for the dredging operations.
1.6
Activities Scheduled for the Next Month
1.6.1
Impact Water Quality Monitoring
during Dredging Operations for CMP 1 will be
conducted three times per week in the next monthly period of April 2013. The sampling schedule is presented in
Annex A.
1.7
Study Programme
1.7.1
A summary of the
Study programme is presented in Annex C.