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

28th MONTHLY PROGRESS REPORT FOR December 2014

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 December 2014, the following works were being undertaken at the CMPs:

·             Capping was being undertaken at ESC CMPs ;

·             Disposal of contaminated mud at SB CMP 2; and

·             Capping operations at SB CMP 1.

Figure 1.1       Works Schedule for ESC CMPs and SB CMPs

1.2                                Reporting Period

1.2.1                          This 28th Monthly Progress Report covers the EM&A activities for the reporting month of December 2014.

1.3                                  Details of Sampling and Laboratory Testing Activities

1.3.1                          The following monitoring activities have been undertaken for ESC CMPs in December 2014.

·             Water Quality Monitoring during Capping Operations of ESC CMPs was undertaken on 9 December 2014; and

·             Benthic Recolonisation Studies of ESC CMPs was undertaken on 16 December 2014.

1.3.2                     The following monitoring activities have been undertaken for SB CMPs in December 2014:

·             Pit Specific Sediment Chemistry of CMP 2 was undertaken on 11 December 2014;

·             Cumulative Impact Sediment Chemistry of CMP 2 was undertaken on 3 December 2014;

·             Water Column Profiling of CMP 2 was undertaken on 4 December 2014; and

·             Water Quality Monitoring during Capping Operations of CMP 1 was undertaken on 9 December 2014.

1.4                                Details of Outstanding Sampling and/or Analysis

1.4.1                          No outstanding sampling remained for December 2014.  The following laboratory analyses were still in progress during the preparation of this monthly report and hence are not presented in this monthly report:

·               Laboratory analyses of sediment samples collected for Benthic Recolonisation Studies of ESC CMPs in December 2014;

·               Laboratory analyses of sediment samples collected for Pit Specific Sediment Chemistry in December; and

·               Laboratory analyses of suspended solids in samples collected for Water Quality Monitoring during Capping of CMP 1.

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

1.5                                Brief Discussion of the Monitoring Results for ESC CMPs

1.5.1                          A brief discussion of the monitoring results of the Water Quality Monitoring during Capping of ESC CMPs conducted on 9 December 2014 is presented below.

1.5.2                          Water Quality Monitoring during Capping – December 2014

1.5.3                          The monitoring results obtained during December 2014 sampling in the dry season 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 2003-2013 from stations in the North Western Water Control Zone (WCZ), where ESC CMPs are located.  For Salinity, the average value obtained from the Reference stations was used for the basis as the WQO.  A total of sixteen (16) monitoring stations were sampled in December 2014 as shown in Figure 1.2Graphical presentation of the monitoring results is provided in Annex B.

In-situ Measurements

1.5.4                          Graphical presentation of the monitoring results is shown in Figures 1-6 of Annex B.  Levels of Dissolved Oxygen (DO), pH and Salinity at all stations in December 2014 complied with the WQO.

Laboratory Measurements for Suspended Solids (SS)

1.5.5                          Concentrations of SS complied with the WQO at all stations in December 2014 (Figure 7 of Annex B).  There did not appear to be any spatial trend of increasing SS levels towards the capping operations.  Further statistical analysis will be undertaken in the quarterly report to investigate whether the capping operations at ESC CMPs is causing any unacceptable deterioration in water quality of the area.

1.6                                Brief Discussion of the Monitoring Results for SB CMPs

1.6.1                          A brief discussion of the monitoring results of the following activities for SB CMPs is presented in this 28th Monthly Progress Report:

·             Cumulative Impact Sediment Chemistry of CMP 2 conducted on 3 December 2014;

·             Water Column Profiling of CMP 2 conducted on 4 December 2014 ; and

·             Water Quality Monitoring during Capping Operations of CMP 1 conducted on 9 December 2014.

1.6.2                          Cumulative Impact Sediment Chemistry of CMP 2 – December 2014

1.6.3                          Monitoring locations for Cumulative Impact Sediment Chemistry for CMP 2 are shown in Figure 1.3.  A total of eleven (11) monitoring stations were sampled in December 2014.

1.6.4                          Analyses of results for the Cumulative Impact Sediment Chemistry Monitoring indicated that the concentrations of all metals, except Arsenic at Capped Pit  SB-RCA Station, were below the Lower Chemical Exceedance Level (LCEL) in December 2014 (Figure 8 and 9 of Annex B). 

1.6.5                          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 exceedance of Arsenic at the Capped Pit SB-RCA Station is unlikely to be caused by the disposal operations at CMP 1 but rather as a result of naturally occurring deposits.

1.6.6                          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 10 of Annex B).  Concentrations of Tributyltin (TBT) were recorded to be higher at Near-field station SB-RNB station (Figure 11 of Annex B).  Total Dichloro-diphenly-trichloroethane (DDT) and 4,4’-Dichloro-diphenly-dichloroenthylene (4,4’-DDE) were recorded below the limit of detection at all stations with no apparent spatial trend .  Concentrations of Total Polychlorinated Biphenyls (PCBs) as well as Low and High Molecular Weight Polycyclic Aromatic Hydrocarbons (Low and High MW PAHs) were recorded below the limit of reporting at all the stations.

1.6.7                          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 during this monthly period.

1.6.8                          Water Column Profiling of CMP 2 – December 2014

1.6.9                          Water Column Profiling was undertaken at a total of two sampling stations (Upstream and Downstream stations) on 4 December 2014.  The water quality monitoring results have been assessed for compliance with the WQO.  The monitoring results were also compared with the Action and Limit Levels set in Baseline Monitoring Report (see Table C2 of Annex C for details). 

In-situ Measurements

1.6.10                      Analyses of results for December 2014 indicated that levels of Salinity, turbidity, DO and pH complied with the WQOs at both Downstream and Upstream stations (Table C1 of Annex C).

Laboratory Measurements for SS

1.6.11                      Analyses of results for December 2014 indicated that the SS levels at both Upstream and Downstream stations complied with the WQO.  SS levels at all stations complied with the Action and Limit Levels (Table C1 of Annex C).

1.6.12                      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.

1.6.13                      Water Quality Monitoring during Capping Operations of CMP 1– December 2014

1.6.14                      The monitoring results obtained during December 2014 sampling in the dry season have been assessed for compliance with the WQOs through a review of the EPD routine water quality monitoring data for the dry season period (November to March) of 2003-2013 from stations in the North Western WCZ, where SB CMP 1 is located.  For Salinity, the average value obtained from the Reference stations was used for the basis as the WQO.  A total of fourteen (14) monitoring stations were sampled in December 2014 as shown in Figure 1.4Graphical presentation of the monitoring results is provided in Annex B.

In-situ Measurements

1.6.15                      Graphical presentation of the monitoring results in shown in Figure 12-17 of Annex B.  Levels of Dissolved Oxygen (DO), pH and Salinity at all stations in December 2014 complied with the WQO.

1.7                                Activities Scheduled for the Next Month

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

·             Pit Specific Sediment Chemistry of CMP 2;

·             Demersal Trawling for CMP2;

·             Routine Water Quality Monitoring for CMP2;

·             Water Column Profiling of CMP 2; and

·             Water Quality Monitoring during Capping Operations of CMP 1.

1.7.2                          No monitoring activities will be conducted in the next monthly period of January 2015 for ESC CMPs.

1.7.3                          The sampling schedule is presented in Annex A.

1.8                                Study Programme

1.8.1                          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