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.



([1])         ERM (2009)  Baseline Monitoring Report.  Environmental Monitoring and Audit for Contaminated Mud Pit at Sha Chau (2009-2013) – Investigation. Agreement No. CE 4/2009(EP).  Submitted to EPD in September 2009.