Agreement No. CE 4/2009 (EP)
Environmental Monitoring and Audit
for Contaminated Mud Pit at Sha Chau
(2009-2013) - Investigation
14th MONTHLY
PROGRESS REPORT FOR CONTAMINATED MUD PITS AT SHA CHAU - August 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 2010. 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 Va-b. The environmental monitoring and audit (EM&A)
programme for the CMPs at the East of Sha Chau area presently covers
disposal operations at CMP IVc and dredging
operations at CMP V.
1.2
Reporting
Period
This Monthly Progress Report
covers the monitoring period of August 2010.
1.3
Details
of Sampling and Laboratory Testing Activities
Field sampling activities conducted in this monthly period for CMP IVc are listed below:
· Benthic Recolonisation
Monitoring and Pit Specific Sediment
Chemistry Monitoring were conducted on 17 August 2010;
· Cumulative Impact Sediment Chemistry Monitoring and Sediment Toxicity Monitoring were
conducted on 19 August 2010;
· Water Column Profiling and Routine Water Quality Monitoring were conducted on 20 August 2010;
and,
· Demersal Trawling was conducted on 25 and 26 August 2010.
For CMP V, sampling for Impact Water Quality Monitoring during
Dredging Operations was conducted on 2,
4 and 6 August 2010. A summary of field activities are presented in Annex A.
A summary of laboratory
analysis results submitted by the Contractor in this reporting month is
presented in Table 1.1.
Table 1.1 Summary
of laboratory analysis results submitted by the Contractor during the reporting
month
|
Key Task |
Monitoring Component |
Results Received from the Contractor |
|
CMP V |
|
|
|
Water Sampling
and Chemical Analysis |
Impact
Monitoring during Dredging Operations |
July’s sampling:
16 August 2010 |
1.4
Details
of Outstanding Sampling and / or Analysis
No outstanding sampling and laboratory analysis remained from August 2010.
1.5
Brief
Discussion of the Monitoring Results
Results of Impact Water Quality Monitoring
during Dredging Operations for August 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 – August 2010
Impact
Water Quality Monitoring during Dredging Operations of CMP V was conducted on
2, 4 and 6 August 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 Figures 1 to 12 of Annex B. Generally, levels of DO, depth-average Turbidity
and TSS complied with the Action and Limit Levels set in the Baseline Monitoring Report ([1]) (Table B1 of
Annex B). However,
very occasional exceedances of Action and Limit Levels
were recorded. For Turbidity and TSS, exceedances of Limit Level were recorded at station DS1
during the mid-flood tide on 4 August 2010.
It should be noted that DS1 is located at the boundary of the works area
and the absence of exceedance at other downstream
stations (DS2 to DS4) indicates that the sediment plume did not extend beyond
the works area. Therefore, it is
considered that the recorded exceedances do not
indicate any adverse water quality impacts caused by the dredging works of CMP
V.
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 for three times
per week. No monitoring will be
conducted for the disposal operations of CMP IV in September 2010.
The sampling schedule is presented in Annex A.
1.7
Study
Programme
A summary of the Study programme is presented in Annex C.