Agreement No. CE 4/2009 (EP)
Environmental Monitoring and Audit
for Contaminated Mud Pit at Sha Chau
(2009-2013) - Investigation
16th
MONTHLY PROGRESS REPORT FOR CONTAMINATED MUD PITS AT SHA CHAU - October 2010
1.1
Background
Since 1992, the East of Sha Chau area has been the site of a series of dredged
contaminated mud pits (CMPs) designed to provide
confined marine disposal capacity for contaminated mud arising from the HKSAR’s dredging and reclamation projects. CMP IVc is
presently in operation for backfilling by contaminated mud and is anticipated
to reach its capacity in 2011. A series
of four newly constructed seabed pits at the East of Sha
Chau area, CMP Va-d, will
be provided for the disposal of contaminated mud after CMP IVc
is full. Dredging operations are now
taking place to construct CMP Vb. The
environmental monitoring and audit (EM&A) programme for the CMPs at the East of Sha Chau area presently covers disposal and capping operations
at CMP IV and dredging operations at CMP Vb.
1.2
Reporting Period
This Monthly Progress Report covers
the monitoring period of October 2010.
1.3
Details of Sampling and
Laboratory Testing Activities
No field sampling activities were scheduled in
this monthly period for CMP IVc. For
CMP V, sampling for Impact Water Quality
Monitoring during Dredging Operations was conducted on
2, 5, 7, 9, 11, 13, 15, 18, 20 and 25 October 2010. A summary of field activities are presented in Annex A.
1.4
Details of Outstanding
Sampling and / or Analysis
No outstanding sampling and laboratory analysis remained from October
2010.
1.5
Brief Discussion of the
Monitoring Results
Results of Impact Water Quality
Monitoring during Dredging Operations for October 2010 are presented for
CMP V. Detailed results will be
discussed in the relevant Quarterly
Reports.
1.5.1
CMP V
Impact Water Quality Monitoring during Dredging
Operations of CMP V – October 2010
Impact
Water Quality Monitoring during Dredging Operations of CMP V was conducted for
three times per week in October 2010. 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 V. Monitoring was also conducted at the Ma Wan
station. At each station, in-situ measurements of water quality
parameters as well as water samples were taken from three depths in the water
column (ie surface: 1 m below sea surface, mid-depth
and bottom: 1 m above the seabed).
Monitoring results are
presented in Table B1 of Annex B.
Generally, levels of Dissolved Oxygen (DO), Turbidity and Total
Suspended Solids (TSS) complied with the Action and Limit Levels set in the Baseline Monitoring Report ([1]). However,
occasional exceedances of these levels are recorded
for Turbidity and TSS (Table B1 of Annex B). Student’s t-tests were then
employed to investigate any significant differences in levels of Turbidity
and/or TSS between Reference (US1 and US2) and Impacts stations where exceedances of Action and Limit Levels were reported (p-value = 0.05).
With the exception of TSS levels recorded at impact station
DS5 during the mid-ebb tide on 7 October and at station DS1 during the
mid-flood tide on 25 October 2010, results of the statistical analysis did not
show any significant differences in levels of Turbidity and TSS between
Reference (US1 and US2) and Impact stations (p-value > 0.05; Table B1 of Annex B). It is thus
considered that these exceedances are more likely to
be caused by background fluctuation in water quality rather than indicating any
adverse impacts from the dredging operations of CMP V. Although recordings of TSS were recorded at
DS5 and DS1 above the levels recorded at the reference stations, these were
isolated events and were tracked with future monitoring.
Overall, there appears to
be no evidence of any unacceptable adverse water quality impacts arising from
the dredging operations of CMP V at ESC.
1.6
Activities Scheduled for the
Next Month
Impact Water Quality
Monitoring during Dredging will be undertaken for CMP V in the next monitoring month. No monitoring will be conducted for the
disposal operations of CMP IV in November 2010.
The sampling schedule is presented in Annex A.
1.7
Study Programme
A summary of the Study programme is presented in Annex C.