Agreement No. CE 23/2012 (EP)
Environmental Monitoring and Audit
for Contaminated Mud Pits to the South of The Brothers and at East Sha Chau (2012-2017) - Investigation

31st MONTHLY PROGRESS REPORT FOR March 2015

1.1                                      Background

1.1.1                                Since early 1990s, contaminated sediment ([1]) arising from various construction works (e.g. dredging and reclamation projects) in Hong Kong has been disposed of at a series of seabed pits at East of Sha Chau (ESC).  In late 2008, a review indicated that the existing and planned facilities at ESC would not be able to meet the disposal demand after 2012.  In order to meet this demand, the Hong Kong Special Administrative Region Government (HKSARG) decided to implement a new contained aquatic disposal (CAD) ([2]) facility at the South of The Brothers (SB CMPs) which had been under consideration for a number of years.

1.1.2                                The environmental acceptability of the construction and operation of the Project had been confirmed by findings of the associated Environmental Impact Assessment (EIA) study completed in 2005 under Agreement No. CE 12/2002(EP) ([3]).  The Director of Environmental Protection (DEP) approved this EIA report under the Environmental Impact Assessment Ordinance (Cap. 499) (EIAO) in September 2005 (EIA Register No.: AEIAR-089/2005).

1.1.3                                In accordance with the EIA recommendation, prior to commencement of construction works for the SB CMPs, the Civil Engineering and Development Department (CEDD) undertook a detailed review and update of the EIA findings for the SB site ([4]).  Findings of the EIA review undertaken in 2009/ 2010 confirmed that the construction and operation of the SB site had been predicted to be environmentally acceptable.

 

1.1.4                                Environmental Permits (EPs) (EP-312/2008/A and EP-427/2011A) were issued by the Environmental Protection Department (EPD) to the CEDD, the Permit Holder, on 28 November 2008 for ESC CMP V and on 23 December 2011 for SB CMPs, respectively.  Under the requirements of the EPs, an Environmental Monitoring and Audit (EM&A) programme as set out in the EM&A Manuals ([5]) ([6]) is required to be implemented for the CMPs.

1.1.5                                The present EM&A programme under Agreement No. CE 23/2012 (EP) covers the dredging, disposal and capping operations of the SB CMPs as well as ESC CMPs.  Detailed works schedule for both CMPs is shown in Figure 1.1.  In March 2015, the following works were being undertaken at the CMPs:

·       Capping operations at ESC CMPs;

·       Capping operations at SB CMP 1; and

·       Disposal of contaminated mud at SB CMP 2.

Figure 1.1       Works Schedule for ESC CMPs and SB CMPs

1.2                                      Reporting Period

1.2.1                                This 31st Monthly Progress Report covers the EM&A activities for the reporting month of March 2015.

1.3                                      Details of Sampling and Laboratory Testing Activities

1.3.1                                                                               No monitoring activities have been undertaken for ESC CMPs in March 2015.

1.3.2                                                                               The following monitoring activities have been undertaken for SB CMPs in March 2015:

·       Pit Specific Sediment Chemistry of CMP 2 was undertaken on 4 March 2015; and

·       Water Column Profiling of CMP 2 was undertaken on 5 March 2015.

1.4                                      Details of Outstanding Sampling and/or Analysis

1.4.1                                No outstanding sampling and laboratory analysis remained for March 2015. 

1.4.2                                A summary of field activities conducted are presented in Annex A.

1.5                                      Brief Discussion of the Monitoring Results for SB CMPs

1.5.1                                                                               Brief discussion of the monitoring results of the following activities for SB CMPs is presented in this 31st Monthly Progress Report:

·       Laboratory analyses of sediment samples collected for Cumulative Impact Sediment Chemistry of SB CMPs in February 2015;

·       Pit Specific Sediment Chemistry of CMP 2 undertaken on 4 March 2015; and

·       Water Column Profiling of CMP 2 undertaken on 5 March 2015.

1.5.2                                Cumulative Impact Sediment Chemistry of SB CMPs – February 2015

1.5.3                                                                               Monitoring locations for Cumulative Impact Sediment Chemistry for SB CMPs are shown in Figure 1.2.  A total of eleven (11) monitoring stations were sampled in February 2015. 

1.5.4                                Analyses of results for the Cumulative Impact Sediment Chemistry Monitoring indicated that the concentrations of most inorganic contaminants, except Arsenic, were below the Lower Chemical Exceedance Level (LCEL) in February 2015 (Figures 1 and 2 of Annex B).  Concentration of Arsenic exceeded the LCEL at Capped Pit station SB-RCA and SB-RCB and Mid Field station SB-RMA. 

1.5.5                                Whilst the average concentration of Arsenic in the Earth’s crust is generally ~2mg/kg, significantly higher Arsenic concentrations (median = 14 mg/kg) have been recorded in Hong Kong’s onshore sediments ([7]).  It is presumed that the natural concentrations of Arsenic are similar in onshore and offshore sediments ([8]), and relatively high Arsenic levels may thus occur throughout Hong Kong.  Therefore, the LCEL exceedances of Arsenic are unlikely to be caused by the disposal operations at CMP 2 but rather as a result of naturally occurring deposits. 

1.5.6                                For organic contaminants, concentration of Total Organic Carbon (TOC) at Tai Ho Bay Station 2 (THB2) was recorded to be higher than other stations (Figure 3 of Annex B).  Concentrations of Tributyltin (TBTs) were recorded to be higher at Near-field station SB-RNB and Ma Wan station (Figure 4 of Annex B).  Total Dichloro-Diphenyl-Trichloroethane (DDT), 4,4’-Dichloro-Diphenyl-Dichloroethylene (4,4’-DDE), Total Polychlorinated Biphenyls (PCBs) as well as Low and High Molecular Weight Polycyclic Aromatic Hydrocarbons (MW PAHs) were recorded below the limit of reporting at all stations.

1.5.7                                Overall, there is no evidence indicating any unacceptable environmental impacts to sediment quality as a result of the contaminated mud disposal operations at CMP 2 in February 2015.  

1.5.8                                Pit Specific Sediment Chemistry of CMP 2 – March 2015

1.5.9                                                                               Monitoring locations for Pit Specific Sediment Chemistry for CMP 2 are shown in Figure 1.3.  A total of six (6) monitoring stations were sampled in March 2015. 

1.5.10                                                                           The concentrations of all inorganic contaminants were lower than the LCEL in March 2015 (Figures 5-6 of Annex B).       

1.5.11                                                                           For organic contaminants, the concentrations of TOC were similar amongst stations in March 2015 (Figure 7 of Annex B).  TBTs concentrations were observed to be slightly higher at Pit Edge station SB-NEBB in March 2015 (Figures 8 of Annex B).  Total DDT, 4,4’-DDE, Total PCBs, Low and High MW PAHs were below the limit of reporting at all stations in March 2015.   

1.5.12                                                                           Overall, there is no evidence indicating any unacceptable environmental impacts to sediment quality as a result of the contaminated mud disposal operations at CMP 2 in March 2015.  Statistical analysis will be undertaken in the quarterly report to investigate whether there are any unacceptable impacts in the area caused by the contaminated mud disposal.

1.5.13                            Water Column Profiling of CMP 2 – March 2015

1.5.14                                                                           Water Column Profiling was undertaken at a total of two sampling stations (Upstream and Downstream stations) on 5 March 2015.  The water quality monitoring results have been assessed for compliance with the Water Quality Objectives (WQOs) through a review of the Environmental Protection Department (EPD) routine water quality monitoring data for the dry season period (November to March) of 2004 – 2013 from stations in the North Western Water Control Zone (WCZ), where SB CMP 2 is located.  For Salinity, the average value obtained from the Reference stations was used for the basis as the WQO.  The monitoring results were also compared with the Action and Limit Levels set in Baseline Monitoring Report (see Table C1 of Annex C for details). 

In-situ Measurements

1.5.15                                                                           Analyses of results for March 2015 indicated that levels of Salinity, Dissolved Oxygen (DO) and pH complied with the WQOs at both Downstream and Upstream stations (Table C2 of Annex C).  DO and Turbidity at all stations complied with the Action and Limit Levels (Table C1 and C2 of Annex C).

Laboratory Measurements for SS

1.5.16                                                                           Analyses of results for February 2015 indicated that the Suspended Solid (SS) levels at both Upstream and Downstream stations complied with the WQO and the Action and Limit Levels (Tables C1 and C2 of Annex C).

1.5.17                                                                           Overall, the monitoring results indicated that the mud disposal operation at CMP 2 did not appear to cause any deterioration in water quality during this reporting period.

 

1.6                                      Activities Scheduled for the Next Month

1.6.1                               The following monitoring activities will be conducted in the next monthly period of April 2015 for SB CMPs:

·       Pit Specific Sediment Chemistry of CMP 2;

·       Water Column Profiling of CMP 2; and

·       Routine Water Quality Monitoring of CMP 2.

1.6.2                                No monitoring activity is scheduled to be conducted in the next monthly period of April 2015 for ESC CMPs.

1.6.3                                The sampling schedule is presented in Annex A.

1.7                                      Study Programme

1.7.1                                A summary of the Study programme is presented in Annex D.

 


([1])       According to the Management Framework of Dredged/ Excavated Sediment of ETWB TC(W) No. 34/2002, contaminated sediment in general shall mean those sediment requiring Type 2 – Confined Marine Disposal as determined according to this TC(W).

([2])        CAD options may involve use of excavated borrow pits, or may involve purpose-built excavated pits.  CAD sites are those which involve filling a seabed pit with contaminated mud and capping it with uncontaminated material such that the original seabed level is restored and the contaminated material is isolated from the surrounding marine environment.7

([3])       Detailed Site Selection Study for a Proposed Contaminated Mud Disposal Facility within the Airport East/ East of Sha Chau Area (Agreement No. CE 12/2002(EP))

([4])       Under the CEDD study Contaminated Sediment Disposal Facility to the South of The Brothers (Agreement No. FM 2/2009)

([5])          ERM (2012) Environmental Monitoring and Audit (EM&A) Manual. Final First Review.  Environmental Monitoring and Audit for Contaminated Mud Pits to the South of the Brothers and at East Sha Chau (2012-2017) – Investigation.  Agreement No. CE 23/2012(EP). Submitted to EPD in November 2012.

([6])         ERM (2010) Environmental Monitoring and Audit (EM&A) Manual. Final Second Review.  Environmental Monitoring and Audit for Contaminated Mud Pit at Sha Chau (2009-2013) – Investigation.  Agreement No. CE 4/2009(EP). Submitted to EPD in November 2010.

([7])    Sewell RJ (1999) Geochemical Atlas of Hong Kong. Geotechnical Engineering Office, Government of the Hong Kong Special Administrative Region

([8])    Whiteside PGD (2000) Natural geochemistry and contamination of marine sediments in Hong Kong. In: The Urban Geology of Hong Kong (ed Page A & Reels SJ). Geological Society of Hong Kong Bulletin No. 6, p109-121