Agreement No. CE 63/2016 (EP)

Environmental Monitoring and Audit
for Disposal Facility to the East of Sha Chau (2017-2020) - Investigation

MONTHLY EM&A REPORT FOR May 2017

1.1                         Background

1.1.1                           The Civil Engineering and Development Department (CEDD) is managing a number of marine disposal facilities in Hong Kong waters, including the Contaminated Mud Pits (CMPs) to the South of The Brothers (SB) and to the East of Sha Chau (ESC) for the disposal of contaminated sediment, and open-sea disposal grounds located to the South of Cheung Chau (SCC), East of Tung Lung Chau (ETLC) and East of Ninepins (ENP) for the disposal of uncontaminated sediment.  Two Environmental Permits (EPs), EP-312/2008/A and EP-427/2011/A, were issued by the Environmental Protection Department (EPD) to the CEDD, the Permit Holder, on 28 November 2008 and 23 December 2011 for the Dredging, Management and Capping of Contaminated Sediment Disposal Facilities at ESC CMP V and SB CMPs, respectively.

1.1.2                           Under the requirements of the two EPs for ESC CMP V and SB CMPs, EM&A programmes which encompass water and sediment chemistry, fisheries assessment, tissue and whole body analysis, sediment toxicity and benthic recolonisation studies as set out in the EM&A Manuals are required to be implemented.  EM&A programmes have been continuously carried out during the operation of the CMPs at ESC and SB.  A review of the collection and analysis of such environmental data from the monitoring programme demonstrated that there had not been any adverse environmental impacts resulting from disposal activities ([1])([2])([3])([4])([5]).  The current programme will assess the impacts resulting from dredging, disposal and capping operations of CMP V as well as capping operations of SB CMPs.

 

1.1.3                           The present EM&A programme under Agreement No. CE 63/2016 (EP) covers the dredging, disposal and capping operations of the ESC CMP V as well as the capping operations of the SB CMPs (see Annex A for the EM&A programme).  Detailed works schedule for ESC CMP V and SB CMPs is shown in Figure 1.1.  In May 2017, the following works were being undertaken:

·      Disposal of contaminated mud at ESC CMP Vd.

Figure 1.1      Works Schedule for ESC CMP V and SB CMPs

1.2                         Reporting Period

1.2.1                     This Monthly EM&A Report for May 2017 covers the EM&A activities for the reporting month of May 2017.

1.3                          Details of Sampling and Laboratory Testing Activities

1.3.1                      The following monitoring activities were undertaken for ESC CMP V in May 2017:

·      Water Column Profiling of ESC CMP Vd was undertaken on 16 May 2017;

·      Pit Specific Sediment Chemistry of ESC CMP Vd was undertaken on 17 May 2017; and

·      Routine Water Quality Monitoring of ESC CMP V was undertaken on 18 May 2017.

1.3.2                      The following monitoring activity was undertaken for SB CMP 2 in May 2017:

·      Water Quality Monitoring During Capping of SB CMPs was undertaken on 31 May 2017.

 

1.4                         Details of Outstanding Sampling and/or Analysis

1.4.1                      No outstanding sampling remained for May 2017.

1.4.2                      The following laboratory analyses are in progress during the preparation of this monthly report and will be presented in the next monthly report once the data are available:

·      Laboratory analyses of sediment samples collected for Pit Specific Sediment Chemistry of ESC CMP Vd in May 2017.

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 Monthly EM&A Report for May 2017:

·      Water Column Profiling of ESC CMP Vd in May 2017; and

·      Routine Water Quality Monitoring of ESC CMP V in May 2017.

1.5.2                      Water Column Profiling of ESC CMP Vd – May 2017

1.5.3                           Water Column Profiling was undertaken at a total of two sampling stations (Upstream and Downstream stations) on 16 May 2017.  The monitoring results 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 2006 - 2015 from stations in the Northwestern Water Control Zone (WCZ), where the ESC CMPs are located ([6]).  For Salinity, the averaged value obtained from the Reference (Upstream) station 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 B1 of Annex B for details). 

In-situ Measurements

1.5.4                           Analyses of results for May 2017 indicated that levels of DO and pH complied with the WQOs at both Downstream and Upstream stations (Table B2 of Annex B).  In addition, DO and Turbidity at all stations complied with the Action and Limit Levels (Tables B1 and B2 of Annex B).

Laboratory Measurements for Suspended Solids (SS)

1.5.5                         Analyses of results for May 2017 indicated that the SS levels complied with the WQO and the Action and Limit Levels at both Upstream and Downstream stations (Tables B1 and B2 of Annex B). 

 

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

1.5.7                      Routine Water Quality Monitoring of ESC CMP V – May 2017

1.5.8                           Routine Water Quality Monitoring of ESC CMP V was undertaken on 18 May 2017.  The monitoring results have been assessed for compliance with the WQOs (see Section 1.5.3 for details).  The monitoring results are shown in Tables B3 and B4 of Annex B and Figures 1 - 10 of Annex C.  A total of ten (10) monitoring stations were sampled in May 2017 as shown in Figure 1.2. 

In-situ Measurements

1.5.9                           Graphical presentation of the monitoring results (Temperature, DO, pH, Salinity and Turbidity) is shown in Figures 1 - 6 of Annex C.  Analyses of results for May 2017 indicated that the levels of pH and DO complied with the WQOs at all stations (Impact, Intermediate, Reference and Ma Wan stations) in May 2017 (Table B3 of Annex B; Figures 1 and 3 of Annex C).  Levels of Salinity at most stations also complied with WQO, except for Ma Wan station (Table B3 of Annex B; Figure 5 of Annex C).  The higher Salinities recorded at Ma Wan station are likely to be caused by the larger separation distance to Pearl River mouth, which release a large amount of freshwater runoff in the area during flooding, when compared to the Reference stations. 

1.5.10                                                             The levels of DO and Turbidity complied with the Action and Limit Levels at all stations (Table B3 of Annex B; Figures 3 and 6 of Annex C).

1.5.11                   Overall, in-situ measurement results of the Routine Water Quality Monitoring indicated that the disposal operation at ESC CMP Vd did not appear to cause any unacceptable impacts in water quality in May 2017. 

Laboratory Measurements

1.5.12                                                               Laboratory analysis of May 2017 results indicated that concentrations of Cadmium, Silver and Mercury were below their limit of reporting at all stations.  Arsenic, Chromium, Nickel, Lead, Copper and Zinc were detected in May 2017 samples and the concentrations of these metals and metalloids were similar amongst stations (Table B4 of Annex B; Figure 7 of Annex C).

1.5.13                                                               For nutrients, concentrations of Total Inorganic Nitrogen (TIN) at all stations in May 2017 were higher than the WQO (0.5 mg/L) (Table B4 of Annex B; Figure 8 of Annex C).  It should be noted that due to the effect of Pearl River, the North Western WCZ has historically experienced higher levels of TIN ([7]).  Therefore, the exceedances of TIN WQO at these stations are unlikely to be caused by the disposal operation at ESC CMP Vd.  Concentrations of Ammonia Nitrogen (NH3-N) were relatively similar amongst all stations in May 2017 (Table B4 of Annex B; Figure 8 of Annex C).  Levels of 5-day Biochemical Oxygen Demand (BOD5) were relatively similar amongst all stations in May 2017 (Table B4 of Annex B; Figure 9 of Annex C). 

1.5.14                                                               Analyses of results for May 2017 indicated that the SS levels complied with the WQO (11.0 mg/L for wet season) and the Action and Limit Levels at all stations (Tables B1 and B4 of Annex B; Figure 10 of Annex C). 

1.5.15                                                              Overall, results of the Routine Water Quality Monitoring indicated that the disposal operation at ESC CMP Vd did not appear to cause any unacceptable deterioration in water quality in May 2017.  Detailed statistical analysis will be presented in the Quarterly Report to investigate any spatial and temporal trends of potential concern.

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 Monthly EM&A Report for May 2017:

·                                                                                             Water Quality Monitoring during Capping Operations of SB CMPs in May 2017.

1.6.2                      Water Quality Monitoring during Capping of SB CMPsMay 2017

1.6.3                                                               Capping works at SB CMP 2 were conducted in May 2017 to supplement and revert the portion of consolidated capping layer to design level and is expected to be completed by December 2017.  The monitoring results obtained during May 2017 sampling in the wet season have been assessed for compliance with the WQOs (see Section 1.5.3 for details).  Levels of DO and Turbidity were also assessed for compliance with the Action and Limit Levels (see Table B5 of Annex B for details).  A total of fourteen (14) monitoring stations were sampled in May 2017 as shown in Figure 1.3.  Graphical presentation of the monitoring results is shown in Figures 11 - 20 of Annex C.

In-situ Measurements

1.6.4                                                                  The levels of pH at all stations in May 2017 complied with the WQO (Table B6 of Annex B; Figure 11 of Annex C).  The levels of Turbidity at all stations complied with the Action and Limit levels in May 2017 (Table B6 of Annex B; Figure 12 of Annex C).  The levels of DO at all stations complied with the WQO and the Action and Limit levels in May 2017 (Table B6 of Annex B; Figure 14 of Annex C).  The levels of Salinity at Impact, Intermediate, Ma Wan, Sham Shui Kok and Tai Mo To stations are higher than the WQO in May 2017 (Table B6 of Annex B; Figure 16 of Annex C).  The Salinities at these stations were higher or above the WQO as they were located further away from the Tai Ho Bay and Reference stations which experienced less freshwater runoff from the nearby streams and Pearl River mouth.

Laboratory Measurements

1.6.5                           The concentrations of SS were higher than the WQO (11.0 mg/L for wet season) at Tai Mo To station in May 2017 (Table B6 of Annex B; Figure 17 of Annex C).  However, levels of SS at all stations complied with the Action and Limit Levels (Table B5 and B6 of Annex B).

1.6.6                          For nutrients, concentrations of NH3-N were relatively similar amongst all stations (Table B6 of Annex B; Figure 18 of Annex C).  The levels of TIN at all stations were higher the WQO of 0.5 mg/L (Table B6 of Annex B; Figure 19 of Annex C).  As discussed in Section 1.5.13, the North Western WCZ has historically experienced higher levels of TIN and such exceedances of TIN WQO at all stations are unlikely to be caused by the capping operation at CMP 2.  Levels of BOD5 were relatively similar amongst all stations (Table B6 of Annex B; Figure 20 of Annex C). 

1.6.7                           Overall, the monitoring results indicated that the capping operation at CMP 2 did not appear to cause any unacceptable deterioration in water quality in May 2017.  Statistical analysis will be undertaken and presented in the quarterly report to investigate whether the capping operations at CMP 2 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 June 2017 for ESC CMP V (see Annex A for the sampling schedule):

·      Water Column Profiling of ESC CMP Vd;

·      Cumulative Impact Sediment Chemistry of ESC CMPs; and.

·      Pit Specific Sediment Chemistry of ESC CMP Vd.

1.7.2                          The following monitoring activities will be conducted in the next monthly period of June 2017 for SB CMPs (see Annex A for the sampling schedule):

·      Water Quality Monitoring During Capping of SB CMPs.

1.8                         Study Programme

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

 


 


([1])    ERM (2013)  Environmental Monitoring and Audit for Contaminated Mud Pit V at East of Sha Chau.  Final Report.  For CEDD.

([2])     ERM (2014)  Environmental Monitoring and Audit for Contaminated Mud Pit V at East of Sha Chau (2012 - 2017).  Final First Annual Review Report.  For CEDD.

([3])     ERM (2015)  Environmental Monitoring and Audit for Contaminated Mud Pit V at East of Sha Chau (2012 - 2017).  Final Second Annual Review Report.  For CEDD.

([4])     ERM (2016)  Environmental Monitoring and Audit for Contaminated Mud Pit V at East of Sha Chau (2012 - 2017).  Final Third Annual Review Report.  For CEDD.

([5])     ERM (2017)  Environmental Monitoring and Audit for Contaminated Mud Pit V at East of Sha Chau (2012 - 2017).  Final Fourth Annual Review Report.  For CEDD.

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

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