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

6th MONTHLY PROGRESS REPORT FOR CONTAMINATED MUD PITS AT SHA CHAU - December 2009

 

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.  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 December 2009.

1.3                                      Details of Sampling and Laboratory Testing Activities

Field sampling activities conducted in this monthly period for CMP IVc are listed below:

·       Benthic Macro In-fauna Monitoring was conducted on 7 December 2009;

·       Cumulative Impact Sediment Chemistry and Sediment Toxicity Monitoring were conducted on 8 December 2009; and,

·       Pit Specific Sediment Chemistry Monitoring and Water Column Profiling were conducted on 9 December 2009.

For CMP V, samplings for Impact Monitoring during Dredging Operations and Water Column Profiling were conducted on 10 and 11 December 2009, respectively.  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 on 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 IV

 

 

Sediment Sampling and Chemical Analysis

 

Sediment Chemistry after a Major Storm Event

September’s sampling:

15 December 2009 

Sediment Toxicity Testing

 

August’s sampling:

15 December 2009

CMP V

 

 

Water Sampling and Chemical Analysis

a) Water Column Profiling

September’s sampling:

15 December 2009

 

 

November’s sampling:

15 December 2009

 

 

b) Impact Monitoring during Dredging Operations

September’s sampling:

15 December 2009

 

 

October’s sampling:

15 December 2009

 

 

November’s sampling:

15 December 2009

1.4                                      Details of Outstanding Sampling and / or Analysis

No outstanding sampling remained from December 2009, however, Water Quality Monitoring during Capping of CMP IV was not conducted as capping activities were not scheduled in this monthly period.  Data for Tissue/Whole Body Contaminant Testing remained outstanding from the Contractor.

1.5                                      Brief Discussion of the Monitoring Results

Results of Sediment Toxicity Testing for August 2009 are presented for CMP IVc.  For CMP V, monitoring results are presented for Water Column Profiling and Impact Monitoring during Dredging Operations for December 2009.  Detailed results will be discussed in the relevant Quarterly Reports.

1.5.1                                CMP IV

Sediment Toxicity Testing in August 2009

Sediment ecotoxicology tests were done on three international species (burrowing amphipod Leptocheirus plumulosus, marine benthic polychaete Neanthes arenaceodentata and marine bivalve Crassostrea gigas) and two local species (barnacle Balanus amphitrite and shrimp Penaeus (Litopenaeus) vannamei).

The survival rates of the burrowing amphipod, bivalve, shrimp and barnacle were not significantly different between animals exposed to Near-Pit and Reference sediments.  The total dry weight of the benthic polychaete was also not significantly different between Near-Pit and Reference sediments. 

1.5.2                                CMP V

Water Column Profiling for CMP V during December 2009

Results of Water Column Profiling for December 2009 show that levels of salinity, pH and DO compiled with the WQOs at both Upstream and Downstream stations (Figures 2 to 4 of Annex B).  Levels of TSS exceeded the WQO at both Upstream and Downstream stations (Figure 1 of Annex B). 

Impact Monitoring during Dredging Operations of CMP V – December 2009

Impact Monitoring during Dredging Operations of CMP V was conducted on 10 December 2009.  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 and water samples were taken from three water depth levels of the water column which were surface (1m below sea surface), mid-depth and bottom (1m above the seabed).

Monitoring results are presented in Figures 5 to 8 of Annex B.  Levels of DO, depth-average Turbidity and TSS complied with the Action and Limit Levels set in the Baseline Monitoring Report ([1]) (Tables B1 and B2 of Annex B). 

1.6                                      Activities Scheduled for the Next Month

The following monitoring activities will be conducted in the next monthly period of January 2010:

·      Demersal Trawling for CMP IV;

·      Impact Monitoring during Dredging Operations for CMP V; and,

·      Water Column Profiling for both CMP IV and CMP V.

The sampling schedule is presented in Annex A. 

1.7                                      Study Programme

A summary of 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 CEDD.