CCF09132017

 

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 August 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 uncontamin ated 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).  Detailed works schedule for ESC CMP V and SB CMPs is shown in Figure 1.1.  In August 2017, the following works were being undertaken:

·      Dredging operation at ESC CMP Vb;

·      Disposal of contaminated mud at ESC CMP Vd; and

·      Capping operation at SB CMP 2.

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 August 2017 covers the EM&A activities for the reporting month of August 2017.

1.3                          Details of Sampling and Laboratory Testing Activities

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

·      Demersal Trawling for ESC CMP V was undertaken on 2 and 3 August 2017;

·      Water Quality Monitoring during Dredging of ESC CMP Vb was undertaken on 2, 4, 7, 9, 11, 21, 25, 28 and 30 August 2017;

·      Pit Specific Sediment Chemistry of ESC CMP Vd was undertaken on 5 August 2017;

·      Sediment Toxicity Tests of ESC CMP V was undertaken on 8 and 10 August 2017;

·      Cumulative Impact Sediment Chemistry of ESC CMP V was undertaken on 8 and 10 August 2017;

·      Water Column Profiling of ESC CMP Vd was undertaken on 12 August 2017;

·      Routine Water Quality Monitoring of ESC CMP V was undertaken on 15 August 2017; and

·      Sediment Chemistry after a Major Storm of ESC CMP V was undertaken on 31 August 2017. 

1.3.2                          The following monitoring activities were undertaken for SB CMPs in August 2017:

·      Benthic Recolonisation Studies of SB CMPs was undertaken on 29 August 2017; and

·      Water Quality Monitoring During Capping of SB CMPs was undertaken on 17 August 2017.

1.4                         Details of Outstanding Sampling and/or Analysis

1.4.1                      No outstanding sampling remained for August 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 Sediment Chemistry after a Major Storm of ESC CMP V in August 2017.

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

·      Species identification of the biota samples collected from Demersal Trawling for ESC CMP V in August 2017;

·      Laboratory analyses of sediment samples collected for Benthic Recolonisation Studies of SB CMPs in August 2017; and

·      Laboratory analyses for Sediment Toxicity Test of ESC CMP V in August 2017.

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 August 2017:

·      Water Quality Monitoring During Dredging of ESC CMP Vb in August 2017;

·      Water Column Profiling of ESC CMP Vd in August 2017;

·      Routine Water Quality Monitoring of ESC CMP V in August 2017;

·      Pit Specific Sediment Chemistry of ESC CMP Vd in August 2017;

·      Cumulative Impact Sediment Chemistry of ESC CMP V in August 2017; and

·      Sediment Chemistry after a Major Storm of ESC CMP V in July 2017.

1.5.2                      Impact Water Quality Monitoring during Dredging Operations of ESC CMP Vb – August 2017

1.5.3                          Dredging activities were carried out on 1 – 11, 17 – 22, 25 – 26, 28 – 31 August 2017 during this reporting period and monitoring was conducted on 2, 4, 7, 9, 11, 21, 25, 28 and 30 August 2017.  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 1.2. Levels of Dissolved Oxygen (DO), Turbidity and Suspended Solid (SS) were assessed for compliance with the Action and Limit Levels (see Table B1 of Annex B for details) set in the Baseline Monitoring Report ([3]).

1.5.4                          Monitoring results are presented in Table B2 of Annex B.  Daily dredging volume in August 2017 is reported in Annex C.  Levels of DO, Turbidity and SS generally complied with the Action and Limit Levels (see Table B1 of Annex B for details) set in the Baseline Monitoring Report ([4]), except for the following occasions discussed in Table 1.1 below.

1.5.5                          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.


 


Table 1.1        Details of Exceedances Recorded at ESC CMP Vb between 2 and 30 August 2017

Date

Tide

Parameter

Station

Type of Exceedance

Remarks

2 August 2017

Mid-Ebb

Bottom DO

DS4

Action

These exceedances were not considered as indicating any unacceptable impacts from the dredging operations to WSRs outside the works area due to the following reasons:

·   Stations DS4 and MW1 are located further away from the works area of CMP Vb when compared to stations DS1-3 at which the levels of Bottom DO did not exceed the Action and Limit Levels during the same tidal period. 

 

2 August 2017

Mid-Ebb

Bottom DO

MW1

Action

2 August 2017

Mid-Flood

Bottom DO

MW1

Action

4 August 2017

Mid-Ebb

Bottom DO

DS4

Action

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

25 August 2017

Mid-Ebb

Turbidity

DS3

Action

These exceedances were not considered as indicating any unacceptable impacts from the dredging operations to WSRs outside the works area due to the following reason:

·        The exceedance was not considered as indicating any unacceptable impacts from the dredging operations to Water Sensitive Receivers (WSRs) outside the works area because Stations DS3, DS4 and DS5 are located further away from the works area of CMP Vd when compared to stations DS1-2 at which the levels of Turbidity did not exceed the Action and Limit Levels during the same tidal period.

·        In addition, levels of SS at all stations complied with the Action and Limit levels.  Therefore, it is considered that the dredging operations did not cause adverse water quality impact in terms of SS levels, which are more representative to determine the effects of dredging operation to nearby sensitive receivers (e.g. fisheries).

25 August 2017

Mid-Ebb

Turbidity

DS5

Action

25 August 2017

Mid-Flood

Turbidity

DS3

Action

25 August 2017

 

 

 

 

 

 

 

 

Mid-Flood

 

 

 

 

 

 

 

 

Turbidity

DS4

Action


1.5.6                      Water Column Profiling of ESC CMP Vd – August 2017

1.5.7                          Water Column Profiling was undertaken at a total of two sampling stations (Upstream and Downstream stations) on 12 August 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 ([5]).  For Salinity, the averaged value obtained from the Reference (Upstream) station 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 B1 of Annex B for details). 

In-situ Measurements

1.5.8                          Analyses of results for August 2017 indicated that levels of DO, Salinity and pH complied with the WQOs at both Downstream and Upstream stations (Table B3 of Annex B).  In addition, levels of DO and Turbidity at all stations complied with the Action and Limit Levels (Tables B1 and B3 of Annex B). 

Laboratory Measurements for Suspended Solids (SS)

1.5.9                      Analyses of results for August 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 B3 of Annex B). 

1.5.10                   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.

 

1.5.11                   Routine Water Quality Monitoring of ESC CMP V – August 2017

1.5.12                       Routine Water Quality Monitoring of ESC CMP V was undertaken on 15 August 2017.  The monitoring results have been assessed for compliance with the WQOs (see Section 1.5.7 for details).  The monitoring results are shown in Tables B4 and B5 of Annex B and Figures 1 - 10 of Annex D.  A total of ten (10) monitoring stations were sampled in August 2017 as shown in Figure 1.3. 

In-situ Measurements

1.5.13                       Graphical presentation of the monitoring results (Temperature, DO, pH, Salinity and Turbidity) is shown in Figures 1 - 6 of Annex D.  Analyses of results for August 2017 indicated that the levels of pH and DO complied with the WQOs at all stations (Impact, Intermediate, Reference and Ma Wan stations) in August 2017 (Table B4 of Annex B; Figures 1 and 3 of Annex D).  Levels of Salinity at most stations also complied with WQO, except for Ma Wan station (Table B4 of Annex B; Figure 5 of Annex D).  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. 

1.5.14                   The levels of DO and Turbidity complied with the Action and Limit Levels at all stations (Table B4 of Annex B; Figures 3 and 6 of Annex D). 

1.5.15                   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 August 2017.  

Laboratory Measurements

1.5.16                                                               Laboratory analysis of August 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 August 2017 samples and the concentrations of these metals and metalloids were similar amongst stations (Table B5 of Annex B; Figure 7 of Annex D). 

1.5.17                                                               For nutrients, concentrations of Total Inorganic Nitrogen (TIN) at all stations in August 2017 were higher than the WQO (0.5 mg/L) (Table B5 of Annex B; Figure 8 of Annex D).  It should be noted that due to the effect of Pearl River, the North Western WCZ has historically experienced higher levels of TIN ([6]).  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 August 2017 (Table B5 of Annex B; Figure 8 of Annex D).  Levels of 5-day Biochemical Oxygen Demand (BOD5) were higher at Ma Wan station in August 2017 (Table B5 of Annex B; Figure 9 of Annex D). 

1.5.18                                                               Analyses of results for August 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 D). 

1.5.19                                                               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 August 2017.  Detailed statistical analysis will be presented in the Quarterly Report to investigate any spatial and temporal trends of potential concern. 

 

1.5.20                   Pit Specific Sediment Chemistry of ESC CMP Vd – August 2017

1.5.21                                                              Monitoring locations for Pit Specific Sediment Chemistry for ESC CMP Vd are shown in Figure 1.4.  A total of six (6) monitoring stations were sampled in August 2017. 

1.5.22                                                          The concentrations of most inorganic contaminants were lower than the Lower Chemical Exceedance Level (LCEL) at all stations in August 2017, except Silver and Copper in August 2017 (Figures 11 and 12 of Annex D).  In August 2017, concentrations of Silver and Copper exceeded the LCEL at Active Pit station ESC-NPAB (Figures 11 and 12 of Annex D).

1.5.23                                                              For organic contaminants, the concentrations of Total Organic Carbon (TOC) were higher at Active Pit station ESC-NPAB in August 2017 (Figure 13 of Annex D).  The concentrations of Tributyltin (TBT) were higher at Active Pit stations ESC-NPAA and ESC-NPAB in August 2017 (Figure 14 of Annex D).  Low and High Molecular Weight Polycyclic Aromatic Hydrocarbons (PAHs), Total Polychlorinated Biphenyls (PCBs), Total dichloro-diphenyl-trichloroethane (DDT) and 4,4’-dichlorodiphenyldichloroethylene (DDE) concentrations were below the limit of reporting at all stations in August 2017.

1.5.24                                                              Overall, 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 August 2017.  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. 

1.5.25                   Cumulative Impact Sediment Chemistry of ESC CMP V – August 2017

1.5.26                                                        Monitoring locations for Cumulative Impact Sediment Chemistry for ESC CMP V are shown in Figure 1.5.  A total of nine (9) monitoring stations were sampled in August 2017. 

1.5.27                   Analyses of results for the Cumulative Impact Sediment Chemistry Monitoring indicated that the concentrations of all inorganic contaminants were below the LCEL in August 2017 (Figures 15 and 16 of Annex D).

1.5.28                   For organic contaminants, concentrations of TOC and TBT were recorded to be higher at Ma Wan station (Figures 17 and 18 of Annex D).  Low and High Molecular Weight PAHs, PCBs, DDT and DDE concentrations were recorded below the limit of reporting at all stations.

1.5.29                   Overall, 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 August 2017.  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.

1.5.30                   Sediment Chemistry after a Major Storm of ESC CMP V – July 2017

1.5.31                   Sampling for Sediment Chemistry after a Major Storm Event was conducted at nine (9) monitoring stations (Figure 1.5) on 25 July 2017 after the visit of tropical cyclone Roke, which led to the issue of Gale or Storm Wind Signal No.8 on 23 July 2017.  The track of Roke is shown in Figure 1.6.

Figure 1.6      Track of Tropical Cyclone Roke from 21 to 23 July 2017 (Source: Hong Kong Observatory)

Track of Roke: 21 – 23 July 2017

1.5.32                   Analyses of results for the Sediment Chemistry after a Major Storm indicated that the concentrations of all inorganic contaminants were below the LCEL (Figures 19 and 20 of Annex D). 

1.5.33                   Overall, there appeared to be no evidence showing the failure of ESC CMP V in retaining disposed mud or causing contamination of sediments after the major storm event in July 2017.

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 August 2017:

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

1.6.2                                                      Water Quality Monitoring during Capping of SB CMPsAugust 2017

1.6.3                           Capping works at SB CMP 2 were conducted in August 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 August 2017 sampling in the wet 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 B6 of Annex B for details).  A total of fourteen (14) monitoring stations were sampled in August 2017 as shown in Figure 1.7.  Graphical presentation of the monitoring results is shown in Figures 21 - 30 of Annex D.

In-situ Measurements

1.6.4                           The levels of pH at all stations in August 2017 complied with the WQO (Table B7 of Annex B; Figure 21 of Annex D).  The levels of Turbidity at all stations complied with the Action and Limit levels in August 2017 (Table B7 of Annex B; Figure 22 of Annex D).  The levels of DO at all stations complied with the WQO and the Action and Limit levels in August 2017, except for Sham Shui Kok station (Table B7 of Annex B; Figure 24 of Annex D).  The level of DO at Sham Shui Kok station is lower than the WQO, however this station is located further away from the works area of CMP 2 when compared to the Impact, Intermediate and Reference stations at which the levels of DO complied with the WQO and the Action and Limit Levels during the same tidal period.  The levels of Salinity at Impact, Intermediate, Ma Wan, Sham Shui Kok and Tai Mo To stations are higher than the WQOmax in August 2017 (Table B7 of Annex B; Figure 26 of Annex D).  The Salinities at these stations were higher than the WQOmax as they were located further away from the Tai Ho Bay and Reference stations, thus experiencing less freshwater runoff from the nearby streams.  The levels of Salinity at Tai Ho Bay 1 and 2 stations are lower than the WQOmin in August 2017 (Table B7 of Annex B; Figure 26 of Annex D).  The lower Salinity levels at Tai Ho Bay 1 and 2 stations are likely to be caused by the freshwater runoff from the nearby streams.

Laboratory Measurements

1.6.5                           The concentrations of SS were higher than the WQO (11.0 mg/L for wet season) at Intermediate, Sham Shui Kok, Tai Mo To and Tai Ho Bay 1 station in August 2017 (Table B7 of Annex B; Figure 27 of Annex D).  However, levels of SS at most stations complied with the Action and Limit Levels, except at Sham Shui Kok and Tai Ho Bay 1 stations (Tables B6 and B7 of Annex B).  Sham Shui Kok and Tai Ho Bay 1 stations are located further away from the works area of CMP 2 when compared to Impact, Intermediate and Reference stations at which the levels of SS did not exceed the Action and Limit Levels during the same tidal period. 

 

1.6.6                           For nutrients, concentrations of NH3-N were relatively similar amongst all stations, except the concentrations of NH3-N recorded at Impact station was lower than the other stations (Table B7 of Annex B; Figure 28 of Annex D).  The levels of TIN at all stations were higher the WQO of 0.5 mg/L (Table B7 of Annex B; Figure 29 of Annex D), except for Ma Wan station.  It is important to note that due to the effect of the Pearl River, the North Western WCZ has historically experienced higher levels of TIN ([7]). 
The exceedances of TIN WQO at these stations are unlikely to be caused by the capping operation at CMP 2.  Levels of BOD5 were higher at Tai Mo To and Tai Ho Bay 2 stations in August 2017 (Table B7 of Annex B; Figure 30 of Annex D). 

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 August 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 September 2017 for ESC CMP V (see Annex A for the sampling schedule):

·      Water Quality Monitoring During Dredging of ESC CMP Vb;

·      Water Column Profiling of ESC CMP Vd; and

·      Pit Specific Sediment Chemistry of ESC CMP Vd. 

1.7.2                     No monitoring activities are scheduled in the next monthly period of September 2017 for SB CMPs.

1.8                         Study Programme

1.8.1                      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])        ERM - Hong Kong, Ltd (2009) Baseline Monitoring Report.  For the Civil Engineering & Development Department, Hong Kong SAR Government.

([4])        ERM - Hong Kong, Ltd (2009) Baseline Monitoring Report.  For the Civil Engineering & Development Department, Hong Kong SAR Government.

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

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

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