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 november 2019

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]).  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).  The scheduled EM&A programme for SB CMPs was completed in December 2018.  Detailed works schedule for ESC CMP V is shown in Figure 1.1.  In November 2019, dredging of accumulated natural deposits at ESC CMP Vb and disposal of contaminated mud at ESC CMP Vd were undertaken.

 

Figure 1.1       Works Schedule for ESC CMP V

1.2                         Reporting Period

1.2.1                     This Monthly EM&A Report for November 2019 covers the EM&A activities for the reporting month of November 2019.

1.3                          Details of Sampling and Laboratory Testing Activities

1.3.1                     The following monitoring activities were undertaken for ESC CMP V in November 2019:

·             Water Column Profiling of ESC CMP Vd;

·             Routine Water Quality Monitoring of ESC CMPs;

·             Pit Specific Sediment Chemistry of ESC CMP Vd; and

·             Water Quality Monitoring During Dredging of ESC CMP Vb.

1.4                         Details of Outstanding Sampling and/or Analysis

1.4.1                     No outstanding sampling remained for November 2019. 

1.5                          Brief Discussion of the Monitoring Results for ESC CMP V

1.5.1                     Brief discussion of the monitoring results of the following activities for ESC CMP V is presented in this Monthly EM&A Report for November 2019:

·             Water Column Profiling of ESC CMP Vd in November 2019;

·             Routine Water Quality Monitoring of ESC CMPs in November 2019;

·             Pit Specific Sediment Chemistry of ESC CMP Vd in November 2019; and

·             Water Quality Monitoring During Dredging of ESC CMP Vb in November 2019.

1.5.2                     Water Column Profiling of ESC CMP Vd – November 2019

1.5.3                     Water Column Profiling was undertaken at a total of two sampling stations (Upstream and Downstream stations) on 6 November 2019.  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 dry season period (November to March) of 2009 - 2018 from stations in the Northwestern Water Control Zone (WCZ), where the ESC CMPs are located ([3]).  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 November 2019 indicated that levels of Salinity, pH and DO complied with the WQOs at both Downstream and Upstream stations (Table B2 of Annex B).  Levels of 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 November 2019 indicated that the SS levels at both Downstream and Upstream stations were complied with the WQO and the Action and Limit Levels (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 CMPs – November 2019

1.5.8                     Routine Water Quality Monitoring of ESC CMP V was undertaken on 7 November 2019.  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 sixteen (16) monitoring stations were sampled in November 2019 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 November 2019 indicated that the levels of pH, Salinity and DO complied with the WQOs at all stations in November 2019. 

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 November 2019. 

Laboratory Measurements

1.5.12                   Laboratory analysis of November 2019 results indicated that concentrations of Arsenic, Chromium, Copper, Lead, Nickel and Zinc were detected in November 2019 samples at most stations and the concentrations of these metals and metalloids were similar amongst the stations, except the concentrations of Copper and Zinc were higher at Ma Wan station (Table B4 of Annex B; Figure 7 of Annex C).    

1.5.13                   For nutrients, concentrations of Total Inorganic Nitrogen (TIN) at all stations complied with WQO, while the concentrations of Ammonia Nitrogen (NH3-N) and 5-day Biochemical Oxygen Demand (BOD5) were generally similar amongst the stations in November 2019 (Table B4 of Annex B; Figure 8 and 9 of Annex C). 

1.5.14                   Analyses of results for November 2019 indicated that the SS levels at all stations were lower than the WQO (13.6 mg/L for dry season) and complied with the Action and Limit Levels (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 November 2019.  Detailed statistical analysis will be presented in the Quarterly Report to investigate any spatial and temporal trends of potential concern.

1.5.16                   Pit Specific Sediment Chemistry of ESC CMP Vd – November 2019

1.5.17                   Monitoring locations for Pit Specific Sediment Chemistry for ESC CMP Vd are shown in Figure 1.3.  A total of six (6) monitoring stations were sampled on 5 November 2019.

1.5.18                   The concentrations of most inorganic contaminants were lower than the Lower Chemical Exceedance Levels (LCELs) at most stations, except for Copper, Lead, Mercury, Silver and Zinc at Active-Pit stations (Figures 11 and 12 of Annex C).  The concentrations of Copper were higher than the Upper Chemical Exceedance Level (UCEL) at Active-Pit station ESC-NPAA and were higher than the LCEL at Active-Pit station ESC-NPAB.  The concentrations of Lead, Mercury and Zinc were higher than the LCEL at Active-Pit station ESC-NPAA.  The concentrations of Silver were higher than the UCEL at Active-Pit station ESC-NPAA. 

1.5.19                   Considering that the higher levels of Copper, Lead, Mercury, Silver and Zinc occurred within Active-Pit stations only but not at the Pit-Edge and Near-Pit stations, there is no evidence indicating any unacceptable environmental impacts to sediment quality as a result of the contaminated mud disposal operations at ESC CMP Vd in November 2019.   

1.5.20                   For organic contaminants, the concentrations of Total Organic Carbon (TOC) were generally similar across Near-Pit and Pit-Edge stations in November 2019, but were higher in Active-Pit stations, especially ESC-NPAA (Figure 13 of Annex C).  The concentrations of Tributyltin (TBT) were generally similar across all stations, except it was lower at Active-Pit stations ESC-NPAA November 2019 (Figure 14 of Annex C).  Total Polychlorinated Biphenyls (PCBs), Total dichloro-diphenyl-trichloroethane (DDT) and 4,4’-dichlorodiphenyldichloroethylene (DDE) concentrations were below the limit of reporting at most stations, except the concentration of PCBs was higher than the limit of reporting at Active-Pit stations ESC-NPAA.  The concentrations of Low Molecular Weight Polycyclic Aromatic Hydrocarbons (PAHs) and High Molecular Weight PAHs exceeded UCEL at Active-Pit station ESC-NPAA and exceeded LCEL at Active-Pit station ESC-NPAB, and the concentration of High Molecular Weight PAHs exceeded LOR at Near-Pit stations ESC-NNAA and ESC-NNAB (Figure 15 of Annex C).

1.5.21                   Considering that the higher levels of PAHs occurred within Active-Pit stations only, there is no evidence indicating any unacceptable environmental impacts to sediment quality as a result of the contaminated mud disposal operations at ESC CMP Vd in November 2019.  

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

1.5.23                   Impact Water Quality Monitoring during Dredging Operations of ESC CMP Vb – November 2019

1.5.24                   Dredging operation at ESC CMP Vb commenced on 11 November 2019.  Water quality monitoring was conducted during the reporting period on 11, 13, 15, 18, 20, 22, 25, 27 and 29 November 2019.  During each 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 Vb.  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 1.4. 

1.5.25                   Monitoring results are presented in Table B5 of Annex B.  Daily dredging volume in November 2019 is reported in Annex D.  Levels of DO, Turbidity and SS complied with the Action and Limit Levels (see Table B1 of Annex B for details).  The results indicated that the dredging operations at ESC CMP Vb 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.

1.6                         Activities Scheduled for the Next Month

1.6.1                     The following monitoring activities will be conducted in the next monthly period of December 2019 for ESC CMP V (see Annex A for the sampling schedule ([4])):

·             Water Column Profiling of ESC CMP Vd;

·             Cumulative Impact Sediment Chemistry of of ESC CMPs;

·             Pit Specific Sediment Chemistry of ESC CMP Vd; and

·             Water Quality Monitoring During Dredging of ESC CMP Vb.

1.7                         Study Programme

1.7.1                     A summary of the Study Programme is presented in Annex E.
 


([1])         ERM (2013)  Final Report.  Submitted under Agreement No. CE 4/2009 (EP) Environmental Monitoring and Audit for Contaminated Mud Pit at East Sha Chau.  For CEDD.

([2])          ERM (2017)  Final Report.  Submitted under 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).  For CEDD.

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

(4)   The scheduled EM&A Programme for SB CMPs was completed in December 2018.