Agreement No. CE 4/2009 (EP)
Environmental Monitoring and Audit
for Contaminated Mud Pit at Sha Chau (2009-2013) - Investigation

 

29th MONTHLY PROGRESS REPORT FOR CONTAMINATED MUD PITS AT SHA CHAU November 2011

 

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 were completed for the construction of CMP Va-b and are now taking place to construct CMP Vc.  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 Vc.

1.2                                      Reporting Period

This Monthly Progress Report covers the monitoring period of November 2011.

1.3                                      Details of Sampling and Laboratory Testing Activities

No field sampling was scheduled for CMP IV in November 2011.

For CMP V, sampling for Impact Water Quality Monitoring during Dredging Operations was conducted on 4 November 2011.  A summary of field activities are presented in Annex A.

A summary of monitoring data submitted by the Contractor in this reporting month is presented in Table 1.1. 

Table 1.1         Summary of monitoring data submitted by the Contractor during the reporting month

Key Task

Monitoring Component

Results Received from the Contractor

CMP V

 

 

Impact Monitoring during Dredging Operations

Water Quality

October 2011 sampling: 28 November 2011

 

 

 

1.4                                      Details of Outstanding Sampling and / or Analysis

No outstanding sampling and laboratory analysis remained from November 2011. 

1.5                                      Brief Discussion of the Monitoring Results

 

1.5.1                                CMP V

Impact Water Quality Monitoring during Dredging Operations of CMP V – November 2011

Impact Water Quality Monitoring during Dredging Operations of CMP V was conducted on 4 November 2011.  On the 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 Vc (Figure 1.1).  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.  Levels of Dissolved Oxygen (DO), Turbidity and Total Suspended Solids (TSS) generally complied with the Action and Limit Levels set in the Baseline Monitoring Report ([1]).  Levels of TSS and Turbidity exceeded the Action Levels in the downstream station DS1 during the mid-flood tide.  Station DS1 is located on the edge of the works area of CMP Vc (Figure 1.1) and the compliance of Action and Limit Levels at other downstream stations (i.e. DS2-4) outside the works area would indicate that there is no evidence of any unacceptable adverse water quality impacts arising from the dredging operations of CMP Vc at ESC.  No additional measures are thus considered required.

1.6                                      Activities Scheduled for the Next Month

The following monitoring programmes will be conducted in the next monthly period of December 2011:

·       Water Column Profiling for CMP IV;

·       Water Quality Monitoring during Capping for CMP IV;

·       Pit Specific Sediment Chemistry for CMP IV;

·       Cumulative Impact Sediment Chemistry for CMP IV;

·       Sediment Toxicity Tests for CMP IV;

·       Benthic Recolonisation Studies for CMP IV; and

·       Impact Water Quality Monitoring during Dredging Operations for CMP V.

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.