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
6TH
MONTHLY PROGRESS REPORT FOR FEBRUARY 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 February 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, 14,
16, 19, 21, 23, 26 and 28 February 2013) in this reporting month in accordance
with the EM&A Manual. No
sampling was conducted between 10 to 12 February 2013 since there were no
dredging works during that period.
1.4.1
No outstanding sampling remained from February 2013. Laboratory analysis of Suspended Solids
(SS) collected after 23 February 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 2 February to 23 February 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 2013
1.5.3
Impact Water Quality Monitoring
during Dredging Operations of CMP 1 was
conducted three times per week with a total of eleven (11) sampling days in
February 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 2 February 2013 to 23 February 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 2, 19 and 23 February
2013.
1.5.5
On 2 February
2013, levels of Turbidity exceeded the Action Level at Impact Stations DS1 and
DS2 and levels of SS exceeded the Limit Level at Impact Stations DS1 and DS2
during mid-flood tide.
1.5.6
On 19 and 23
February 2013, levels of SS exceeded the Action Level at Impact Station DS1
during mid-flood tide.
1.5.7
Stations DS1 and
DS2 are located in close proximity to the works area of CMP 1 (ie within 500m from the works area). Since the exceedances
were recorded at stations DS1 and DS2 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.
1.5.8
Exceedance of Action and
Limit Level was not recorded at any Sensitive Receiver stations. As such, the dredging works did not
appear to cause any unacceptable water quality impacts at the Sensitive
Receivers.
1.5.9
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 March 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.