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

42nd MONTHLY PROGRESS REPORT FOR february 2016

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 February 2016, the following works were being undertaken at the CMPs:

P       Dredging operation at ESC CMP Vd;

P       Capping operation at ESC CMP Va; and

P       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 42nd Monthly Progress Report covers the EM&A activities for the reporting month of February 2016.

1.3                                      Details of Sampling and Laboratory Testing Activities

1.3.1                                The following monitoring activities have been undertaken for ESC CMPs in February 2016:

P       Impact Water Quality Monitoring during Capping Operations of ESC CMP Va was undertaken on 17 February 2016;and

P       Impact Water Quality Monitoring during Dredging Operations of ESC CMP Vd was undertaken on 22 February 2016.

1.3.2                           The following monitoring activities have been undertaken for SB CMPs in February 2016:

P       Water Column Profiling of CMP 2 was undertaken on 1 February 2016;

P       Cumulative Impact Sediment Chemistry of SB CMPs was undertaken on 2 and 3 February 2016;

P       Sediment Toxicity Test of CMP 2 was undertaken on 2 and 3 February 2016;

P       Pit Specific Sediment Chemistry of CMP 2 was undertaken on 4 February 2016;

P       Impact Water Quality Monitoring during Capping Operations of SB CMP 2 was undertaken on 11 February 2016;

P       Routine Water Quality Monitoring of CMP 2 was undertaken on 19 February 2016; and

P       Demersal Trawling for SB CMPs was undertaken on 23 and 24 February 2016.

1.4                                      Details of Outstanding Sampling and/or Analysis

1.4.1                                No outstanding sampling remained for February 2016. 

1.4.2                                The following laboratory analyses are in progress and will be presented in the corresponding quarterly report:

P  Taxonomic identification of fishery resources collected during Demersal Trawling for SB CMPs and subsequent chemical analysis for the biota samples collected in January and February 2016.

P  Laboratory analyses of sediment samples collected for Sediment Toxicity Tests of CMP 2 in February 2016.

1.5                                      Brief Discussion of the Monitoring Results for ESC CMPs

1.5.1                                                                               Brief discussion of the monitoring results of the following activities for ESC CMPs is presented in this 42nd Monthly Progress Report:

P       Impact Water Quality Monitoring during Dredging Operations of ESC CMP Vd in February 2016; and

P       Water Quality Monitoring During Capping of CMP Va in February 2016.

1.5.2                                                                               Impact Water Quality Monitoring during Dredging Operations of ESC CMP Vd V February 2016

1.5.3                                Dredging activities were carried out on 19 - 23 February 2016 during this reporting period and monitoring was conducted on 22 February 2016.  During the survey day, monitoring was conducted during both mid-ebb and mid-flood tides at two Reference (Upstream) stations and five Impact (Downstream) stations around the dredging operations at ESC CMP Vd.  Monitoring was also conducted at one Sensitive Receiver station situated in Ma Wan.  A total of eight (8) stations were monitored and locations of the sampling stations are shown in Figure 1.2. 

1.5.4                                Monitoring results are presented in Table B1 of Annex B.  Daily dredging volume in February 2016 is reported in Annex C.  Levels of Dissolved Oxygen (DO), Turbidity and Suspended Solid (SS) complied with the Action and Limit Levels (see Table B2 of Annex B for details) set in the Baseline Monitoring Report ([7]).

1.5.5                                The results indicated that the dredging operations at ESC CMP Vd did not appear to cause any unacceptable deterioration in water quality during this reporting period.  Therefore, no further action, except for those recommended in the Environmental Permit (EP-312/2008/A), are considered necessary for the dredging operations.

1.5.6                                Water Quality Monitoring during Capping of ESC CMPs V February 2016

1.5.7                                The monitoring results obtained during February 2016 sampling in the dry season have been assessed for compliance with the Water Quality Objectives (WQOs) set by Environmental Protection Department (EPD).  This consists of a review of the EPD routine water quality monitoring data for the dry season period (November to March) of 2005 - 2014 from stations in the Northwestern Water Control Zone (WCZ), where the ESC CMPs are located ([8]).  For Salinity, the averaged value obtained from the Reference stations was used for the basis as the WQO.  Levels of DO and Turbidity were also assessed for compliance with the Action and Limit Levels (see Table B2 of Annex B for details).  A total of ten (10) monitoring stations were sampled in February 2016 as shown in Figure 1.3.   

In-situ Measurements

1.5.8                                Graphical presentation of the monitoring results (Temperature, DO, pH, Salinity and Turbidity) is shown in Figures 1-6 of Annex D.  Levels of Salinity, DO and pH at all stations in February 2016 complied with the WQO (Table B3 of Annex B).  Level of DO and Turbidity also complied the Action and Limit levels (Table B3 of Annex B). 

Laboratory Measurements for Suspended Solids (SS)

Concentrations of SS complied with the WQO and the Action and Limit Levels at all stations in February 2016 (Table B3 of Annex B; Figure 7 of Annex D).  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                                                                               Brief discussion of the monitoring results of the following activities for SB CMPs is presented in this 42nd Monthly Progress Report:

P       Pit Specific Sediment Chemistry of CMP 2 in January and February 2016;

P       Cumulative Impact Sediment Chemistry of CMP 2 in February 2016;

P       Routine Water Quality Monitoring of CMP 2 in February 2016;

P       Water Column Profiling of CMP 2 in February 2016; and

P       Impact Water Quality Monitoring during Capping Operations of SB CMP 2 in February 2016.

1.6.2                                Pit Specific Sediment Chemistry of CMP 2 V January and February 2016

1.6.3                                                                               Monitoring locations for Pit Specific Sediment Chemistry for CMP 2 are shown in Figure 1.4.  A total of six (6) monitoring stations were sampled in January and February 2016. 

1.6.4                                                                               The concentrations of most inorganic contaminants (Arsenic, Cadmium, Chromium, Lead, Mercury, Nickel and Zinc) were lower than the Lower Chemical Exceedance Level (LCEL) at all stations, except Silver and Copper (Figures 8, 9, 13 and 14 of Annex D).  In January 2016, Silver and Copper exceeded the LCEL at both Active Pit stations SB-NPBA and SB-NPBB (Figure 9 of Annex D).  In February 2016, Silver and Copper exceeded the LCEL at Active Pit station SB-NPBB (Figure 14 of Annex D). 

1.6.5                                                                               For organic contaminants, the concentrations of Total Organic Carbon (TOC) were similar amongst most stations and it was observed to be lower at Pit Edge station SB-NPBB in January and February 2016 (Figures 10 and 15 of Annex D).  Tributyltin (TBT) concentrations were observed to be higher at Active Pit stations SB-NPBA (Figures 11 and 16 of Annex D).  4,4-dichlorodiphenyldichloroethylene (DDE) concentrations were observed to be higher at Active Pit SB-NPBB in January and February 2016 (Figures 12 and 17 of Annex D).   Total dichlorodiphenyltrichloroethane (DDT) concentrations were observed to be higher at Pit Edge station SB-NEBA and Active Pit station SB-NPBB in February 2016 whilst concentrations of DDT were below limit of reporting at all stations in January 2016 (Figure 12 of Annex D).  Low and High Molecular Weight Polycyclic Aromatic Hydrocarbons (PAHs), Total Polychlorinated Biphenyls (PCBs) and concentrations were below the limit of reporting at all stations.

1.6.6                                                                               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 January and February 2016.  Statistical analysis will be undertaken and presented in the quarterly report to investigate whether there are any unacceptable impacts in the area caused by the contaminated mud disposal.

 

1.6.7                                Cumulative Impact Sediment Chemistry of SB CMPs V February 2016

1.6.8                                                                               Monitoring locations for Cumulative Impact Sediment Chemistry for SB CMPs are shown in Figure 1.5.  A total of eleven (11) monitoring stations were sampled in February 2016. 

1.6.9                                Analyses of results for the Cumulative Impact Sediment Chemistry Monitoring indicated that the concentrations of all inorganic contaminants, except Arsenic concentrations in Far-field station SB-RFB, were below the LCEL in February 2016 (Figures 18 and 19 of Annex D).

1.6.10                            Whilst the average concentration of Arsenic in the Earths crust is generally ~2mg/kg, significantly higher Arsenic concentrations (median = 14 mg/kg) have been recorded in Hong Kongs onshore sediments ([9]).  It is presumed that the natural concentrations of Arsenic are similar in onshore and offshore sediments ([10]), and relatively high Arsenic levels may thus occur throughout Hong Kong.  Therefore, the LECL exceedances of Arsenic are unlikely to be caused by the disposal operations at CMP 2 but rather as a result of naturally occurring deposits.

1.6.11                            For organic contaminants, concentrations of TOC at Near-field station SB-RNA was recorded to be lower than other stations (Figure 20 of Annex D).  Concentrations of TBTs were recorded to be higher at Ma Wan station (Figure 21 of Annex D).  Total DDT, 4,4-DDE, Total PCBs as well as Low and High Molecular Weight PAHs were recorded below the limit of reporting at all stations.

1.6.12                            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 February 2016.  Statistical analysis will be undertaken and presented in the quarterly report to investigate whether there are any unacceptable impacts in the area caused by the contaminated mud disposal.

1.6.13                            Routine Water Quality Monitoring of SB CMP 2 V February 2016

1.6.14                            Routine Water Quality Monitoring was undertaken at a total of two sampling stations (Upstream and Downstream stations) on 19 February 2016.  The monitoring results have been assessed for compliance with the WQOs (see Section 1.5.7 for details).  Levels of DO and Turbidity were also assessed for compliance with the Action and Limit Levels (see Table B4 of Annex B for details).  The monitoring results are shown in Tables B5 and B6 of Annex B and Figures 22 - 31 of Annex D.  A total of twenty (20) monitoring stations were sampled in February 2016 as shown in Figure 1.6. 

 

In-situ Measurements

1.6.15                                                                           Graphical presentation of the monitoring results (Temperature, DO, pH, Salinity and Turbidity) is shown in Figures 22 - 27 of Annex D.  Analyses of results for February 2016 indicated that the levels of pH, DO and Salinity complied with the WQOs at all stations (Impact, Intermediate, Reference and Water Sensitive Receiver stations) in February 2016 (Table B5 of Annex B; Figures 22 - 24, 26 of Annex D).

1.6.16                                                                           The levels of DO and Turbidity complied with the Action and Limit Levels at all stations (Table B5 of Annex B; Figures 24 and 27 of Annex D).

1.6.17                            Overall, in-situ measurement results of the Routine Water Quality Monitoring indicated that the disposal operation at CMP 2 did not appear to cause any unacceptable impacts in water quality in February 2016. 

Laboratory Measurements

1.6.18                                                                           Laboratory analysis of February 2016 results indicated that concentrations of Cadmium, Chromium, Nickel, Lead, Silver and Mercury were below their limit of reporting at all stations.  Arsenic, Copper and Zinc were detected in February 2016 samples and the concentrations were similar amongst stations (Table B6 of Annex B; Figure 28 of Annex D).   

1.6.19                                                                           For nutrients, concentrations of Total Inorganic Nitrogen (TIN) at Tai Ho Bay 2 station in February 2016 exceeded the WQO (0.5 mg/L) (Table B6 of Annex B; Figure 29 of Annex D).  It should be noted that due to effect of Pearl River, the North Western WCZ has historically experienced higher levels of TIN ([11]).  Since TIN concentrations were recorded to be similar amongst all stations, the exceedances of TIN WQO at all stations are unlikely to be caused by the disposal operation at CMP 2.  Ammonia Nitrogen (NH3-N) concentration was relatively similar amongst all stations (Table B6 of Annex B; Figure 29 of Annex D).  Levels of 5-day Biochemical Oxygen Demand (BOD5) appear to be higher at Tai Ho Bay 1 and Shum Shui Kok stations in February 2016 (Table B6 of Annex B; Figure 30 of Annex D). 

1.6.20                                                                           Concentrations of SS complied with the WQO (13.5 mg/L for dry season) and the Action and Limit Levels at all stations in February 2016 (Table B6 of Annex B; Figure 32 of Annex D). 

1.6.21                            Overall, results of the Routine Water Quality Monitoring indicated that the disposal operation at CMP 2 did not appear to cause any unacceptable deterioration in water quality in February 2016.  Detailed statistical analysis will be presented in the Quarterly Report to investigate any spatial and temporal trends of potential concern.


 

1.6.22                            Water Column Profiling of CMP 2 V February 2016

1.6.23                           Water Column Profiling was undertaken at a total of two sampling stations (Upstream and Downstream stations) on 1 February 2016.  The monitoring results have been assessed for compliance with the WQOs (see Section 1.5.7 for details).   Levels of DO and Turbidity were also assessed for compliance with the Action and Limit Levels (see Table B4 of Annex B for details).

In-situ Measurements

1.6.24                           Analyses of results for February 2016 indicated that levels of Salinity, DO and pH complied with the WQOs at both Downstream and Upstream stations (Table B7 of Annex B).  In addition, DO and Turbidity at all stations complied with the Action and Limit Levels (Table B7 of Annex B).

Laboratory Measurements for SS

1.6.25                            Analyses of results for February 2016 indicated that the SS levels exceeded the WQO at both Upstream and Downstream stations.  However, both Upstream and Downstream stations complied with the Action and Limit Levels (Table B7 of Annex B).

1.6.26                            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.

1.6.27                            Water Quality Monitoring during Capping of SB CMP 1 V February 2016

1.6.28                            The monitoring results obtained during February 2016 sampling in the dry season have been assessed for compliance with the WQOs (see Section 1.5.7 for details).  Levels of DO and Turbidity were also assessed for compliance with the Action and Limit Levels (see Table B4 of Annex B for details).  A total of fourteen (14) monitoring stations were sampled in February 2016 as shown in Figure 1.7.  Graphical presentation of the monitoring results is provided in Annex D. 

In-situ Measurements

1.6.29                                                                           Graphical presentation of the monitoring results (Temperature, DO, pH, Salinity and Turbidity) is shown in Figures 32-37 of Annex D.  Levels of pH and Salinity at all stations in February 2016 complied with the WQO (Table B8 of Annex B; Figures 32 and 37 of Annex D).  The levels of Turbidity at all stations complied with the Action and Limit levels in February 2016. (Table B8 of Annex B; Figure 33 of Annex D).  DO at all stations also complied with the WQO and the Action and Limit levels in February 2016 (Table B8 of Annex B; Figure 35 of Annex D). 

Laboratory Measurement

1.6.30                            Concentrations of SS were recorded higher than the WQO (13.5 mg/L for dry season) at Reference, Intermediate, Ma Wan, Sham Shui Kok and Tai Mo To stations in February 2016 (Table B8 of Annex B; Figure 39 of Annex B).  However, SS at all stations complied with the Action and Limit Levels in February 2016 (Table B8 of Annex B).

1.6.31                            For nutrients, concentrations of NH3 were relatively similar amongst all stations (Table B8 of Annex B; Figure 39 of Annex D).  TIN at Reference, Impact, Sham Shui Kok, Tai Mo To and Tai Ho Bay 1 stations exceeded the WQO of 0.5 mg/L in February 2016 (Table B8 of Annex B; Figure 41 of Annex D).  As discussed in Section 1.6.19, the North Western WCZ has historically experienced higher levels of TIN and the exceedances of TIN WQO at these stations are unlikely to be caused by the capping operation at CMP 1. 

1.6.32                            Concentrations of BOD5 were similar at all stations in February 2016 (Table B8 of Annex B; Figure 41 of Annex D).  

1.6.33                            Statistical analysis will be undertaken and presented in the quarterly report to investigate whether the capping operations at CMP 1 is causing any unacceptable impacts in water quality of the area.

 

1.7                                      Activities Scheduled for the Next Month

1.7.1                               The following monitoring activities will be conducted in the next monthly period of March 2016 for SB CMPs:

P       Pit Specific Sediment Chemistry of CMP 2; and

P       Water Column Profiling of CMP 2.

1.7.2                               The following monitoring activities will be conducted in the next monthly period of March 2016 for ESC CMPs:

P       Pit Specific Sediment Chemistry of ESC CMP Vd; and

P       Water Column Profiling of ESC CMP Vd.

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 E.

 


 



([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 V 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) V 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) V Investigation.  Agreement No. CE 4/2009(EP). Submitted to EPD in November 2010.

([7])        ERM (2009).  Draft Second Review of the EM&A Manual.  Under Agreement No. CE 4/2009 (EP) EM&A for Contaminated Mud Pit at Sha Chau (2009-2013) V Investigation

([8])        http://epic.epd.gov.hk/EPICRIVER/marine/?lang=en

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

([10]) 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

([11])     http://www.epd.gov.hk/epd/misc/marine_quality/1986-2005/textonly/eng/index.htm