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

9th MONTHLY PROGRESS REPORT FOR CONTAMINATED MUD PITS AT SHA CHAU - March 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.  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 March 2010.

1.3                                      Details of Sampling and Laboratory Testing Activities

No field sampling activities were scheduled for CMP IVc in this monthly period.  For CMP V, sampling for Impact Monitoring during Dredging Operations was conducted on 15 March 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 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

 

 

Water Sampling and Chemical Analysis

Routine water quality monitoring

February’s sampling:

30 March 2010

 

Sediment Sampling and Chemical Analysis

Sediment Toxicity Monitoring

December’s sampling:

9 March 2010

 

 

 

Demersal Trawling and Tissue Analysis

Demersal Trawling

February’s Sampling:

30 March 2010

 

 

 

CMP V

 

 

Water Sampling and Chemical Analysis

Impact Monitoring during Dredging Operations

March’s sampling:

23 March 2010

 

 

 

1.4                                      Details of Outstanding Sampling and / or Analysis

No outstanding sampling and laboratory analysis remained from March 2010. 

1.5                                      Brief Discussion of the Monitoring Results

Results of Sediment Toxicity Monitoring for December 2009 and Routine Water Quality Monitoring for February 2010 are presented for CMP IV.  Results of Impact Monitoring during Dredging Operations for March 2010 are presented for CMP V.  Detailed results will be discussed in the relevant Quarterly Reports.

1.5.1                                CMP IV

Sediment Toxicity Testing in December 2009

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

The survival rates of the amphipod, polychaete, bivalve, shrimp and barnacle were not significantly different between animals exposed to Near-Pit and Reference sediments.  Other indicators i.e. individual & total dry weight and growth rate of the benthic polychaete were also not significantly different between animals exposed to Near-Pit and Reference sediments. 


Routine Water Quality Monitoring in February 2010

Laboratory Analysis

Concentrations of copper, zinc and nickel were lower at the Impact stations than at the Intermediate and Reference stations.  Lead concentrations were similar across the sampling stations (Figure 1 of Annex B).  All other metals sampled were below the limits of detection.  Mean Total Suspended Solids (TSS) level was the lowest at the Impact Stations.  Mean TSS levels at the Intermediate and Reference stations exceeded the WQO (Figure 3 of Annex B).  Nitrogenous nutrients (NH3 and TIN) and BOD showed minor variation in concentrations between stations (Figures 2 & 4 of Annex B). 

1.5.2                                CMP V

Impact Monitoring during Dredging Operations of CMP V – March 2010

Impact Monitoring during Dredging Operations of CMP V was conducted on 15 March 2010.  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

Pit Specific Sediment Chemistry Monitoring for CMP IV and Impact Monitoring during Dredging Operations for CMP V are scheduled in the next monthly period of April 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.