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

40th MONTHLY PROGRESS REPORT FOR December 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 December 2015, the following works were being undertaken at the CMPs:

·       Dredging operation at ESC CMP Vd;

·       Capping operations at ESC CMP Va; 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 40th Monthly Progress Report covers the EM&A activities for the reporting month of December 2015.

1.3                                      Details of Sampling and Laboratory Testing Activities

1.3.1                                The following monitoring activities have been undertaken for ESC CMPs in December 2015:

·       Benthic Recolonisation Studies of CMP IV was undertaken on 9 December 2015;

·       Water Quality Monitoring During Capping of CMP Va was undertaken on 10 December 2015; and

·       Impact Water Quality Monitoring during Dredging Operations of ESC CMP Vd was undertaken on 30 December 2015.

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

·       Water Column Profiling of CMP 2 was undertaken on 1 December 2015;

·       Water Quality Monitoring During Capping of CMP 1 was undertaken on 2 December 2015;

·       Benthic Recolonisation Studies of CMP 1 was undertaken on 3 December 2015;

·       Pit Specific Sediment Chemistry of CMP 2 was undertaken on 7 December 2015; and

·       Cumulative Impact Sediment Chemistry of SB CMPs were undertaken on 7 and 8 December 2015;

1.4                                      Details of Outstanding Sampling and/or Analysis

1.4.1                                No outstanding sampling remained for December 2015. 

1.4.2                                A summary of field activities conducted are presented in Annex A.  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 Pit Specific Sediment Chemistry of SB CMP 2 in December 2015.

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

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

·  Laboratory analyses of sediment samples collected for Benthic Recolonisation Studies of ESC CMP IV and SB CMP 1 in December 2015.

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 40th Monthly Progress Report:

·       Impact Water Quality Monitoring during Dredging Operations of ESC CMP Vd in December 2015; and

·       Water Quality Monitoring During Capping of CMP Va in December 2015.

1.5.2                                                                               Impact Water Quality Monitoring during Dredging Operations of ESC CMP Vd – December 2015

1.5.3                                Dredging activities were carried out on 13 - 14, 19 – 21 and 28 – 31 December 2015 during this reporting period.  However, as the dredging contractor could not confirm the works schedule until the dredger arrived the site and there was insufficient time allowed for the deployment of the sampling vessel , Impact Water Quality Monitoring during Dredging Operations of ESC CMP Vd could not be arranged during the period of 13 – 14 and 19 – 21 December 2015 when dredging was being conducted.  The situation was then discussed between ET, CEDD and the dredging contractor and it is agreed that the dredging contractor would confirm the works schedule with ET and CEDD at least one week before the actual works.  The situation was then rectified and Impact Water Quality Monitoring for Dredging Operations was conducted on 30 December 2015 to monitor water quality around the ESC CMP Vd during dredging activities on 28 – 31 December 2015.  On 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 December 2015 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 – December 2015

1.5.7                                The monitoring results obtained during December 2015 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 wet season period (April to October) of 2005 - 2014 from stations in the Northwestern Water Control Zone (WCZ), where the CMPs are located ([8]).  For Salinity, the averaged value obtained from the Reference stations was used for the basis as the WQO.  Levels of Dissolved Oxygen (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 sixteen (16) monitoring stations were sampled in December 2015 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 December 2015 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 December 2015 (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 40th Monthly Progress Report:

·       Pit Specific Sediment Chemistry of CMP 2 in November 2015;

·       Water Quality Monitoring During Capping of CMP 1 was in December 2015; and

·       Water Column Profiling of CMP 2 in November 2015.

1.6.2                                Pit Specific Sediment Chemistry of CMP 2 – November 2015

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 November 2015. 

1.6.4                                                                               The concentrations of all inorganic contaminants (Arsenic, Cadmium, Chromium, Copper, Lead, Mercury, Nickel, Silver and Zinc) were lower than the Lower Chemical Exceedance Level (LCEL) at all stations (Figures 8 and 9 of Annex D). 

1.6.5                                                                               For organic contaminants, the concentrations of Total Organic Carbon (TOC) were similar at most stations and it was observed to be lower at Active Pit station SB-NPBB (Figure 10 of Annex D).  Tributyltin (TBT) concentrations were observed to be higher at Near Pit station SB-NNBA (Figure 11 of Annex D).  Low and High Molecular Weight Polycyclic Aromatic Hydrocarbons (PAHs), Total Polychlorinated Biphenyls (PCBs), 4,4’-dichlorodiphenyldichloroethylene (DDE) and Total dichlorodiphenyltrichloroethane (DDT) concentrations were below the limit of reporting at most stations, except High Molecular Weight PAHs at Active Pit stations SB-NPBB (Figure 12 of Annex D).   

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 November 2015.  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                                Water Quality Monitoring during Capping of SB CMP 1 – December 2015

1.6.8                                The monitoring results obtained during December 2015 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 December 2015 as shown in Figure 1.5.  Graphical presentation of the monitoring results is provided in Annex D. 

In-situ Measurements

1.6.9                                                                               Graphical presentation of the monitoring results (Temperature, DO, pH, Salinity and Turbidity) is shown in Figures 13-18 of Annex D.  Levels of pH and Salinity at all stations in December 2015 complied with the WQO (Table B5 of Annex B; Figures 13-18 of Annex D).  DO at all stations also complied with the WQO and the Action and Limit levels in December 2015 (Table B5 of Annex B; Figure 16 of Annex D).  In addition, the levels of Turbidity at most stations complied with the Action and Limit levels in December 2015, except for Tai Ho Bay 1 station (Table B5 of Annex B; Figure 14 of Annex D).  The exceedance of Limit levels at Tai Ho Bay 1 station was unlikely to be caused by the capping operation at SB as the levels of Turbidity complied with the Action and Limit levels at all other stations, including Impact stations which are located closer to CMP 1.

Laboratory Measurement

1.6.10                            Concentrations of SS complied with the WQO (13.5 mg/L for dry season) at Intermediate, Ma Wan, Tai Ho Bay 2 and Sham Shui Kok stations, but not at Reference, Impact, Tai Ho Bay 1 and Tai Mo To stations in December 2015 (Table B5 of Annex B; Figure 19 of Annex B).  SS at most stations complied with the Action and Limit Levels in December 2015, except the exceedance of Tai Ho Bay 1 station (Table B5 of Annex B).  The exceedance of Action level at Tai Ho Bay 1 station was unlikely to be caused by the capping operation at SB as the levels of SS complied with the Action and Limit levels at all other stations, including Impact stations which are located closer to CMP 1.

1.6.11                            For nutrients, concentrations of Ammonia (NH3) were relatively similar amongst all stations (Table B5 of Annex B; Figure 20 of Annex D).  Total Inorganic Nitrogen (TIN) at most stations exceeded the WQO of 0.5 mg/L in December 2015, except Ma Wan (Table B5 of Annex B; Figure 21 of Annex D).  It should be noted that 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. 

1.6.12                            Concentrations of Biochemical Oxygen Demand (BOD5) were similar at all stations in December 2015 (Table B5 of Annex B; Figure 22 of Annex D). 

1.6.13                            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.

1.6.14                            Water Column Profiling of CMP 2 – December 2015

1.6.15                                                                           Water Column Profiling was undertaken at a total of two sampling stations (Upstream and Downstream stations) on 1 December 2015.  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

1.6.16                                                                           Analyses of results for December 2015 indicated that levels of Salinity, DO and pH complied with the WQOs at both Downstream and Upstream stations (Table B6 of Annex B).  In addition, DO and Turbidity at all stations complied with the Action and Limit Levels (Table B6 of Annex B).

Laboratory Measurements for SS

1.6.17                                                                           Analyses of results for December 2015 indicated that the SS levels complied with the WQO at Downstream stations.  Both Upstream and Downstream stations complied with the Action and Limit Levels (Table B6 of Annex B).

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.


 

1.7                                      Activities Scheduled for the Next Month

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

·       Pit Specific Sediment Chemistry of CMP 2;

·       Routine Water Quality Monitoring of CMP 2;

·       Water Column Profiling of CMP 2; and

·       Demersal Trawling of SB CMPs.

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

·       Impact Water Quality Monitoring during Dredging Operations of 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 – 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])        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) – Investigation

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