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

52nd MONTHLY PROGRESS REPORT FOR December 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-427/2011/A) 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 ESC CMPs and SB CMPs is shown in Figure 1.1.  In December 2016, 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 CMPs and SB CMPs

1.2                                Reporting Period

1.2.1                       This 52nd Monthly Progress Report covers the EM&A activities for the reporting month of December 2016.

1.3                              Details of Sampling and Laboratory Testing Activities

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

·      Water Column Profiling of ESC CMP Vd was undertaken on 1 December 2016;

·      Water Quality Monitoring During Dredging of ESC CMP Vb was undertaken on 2, 5, 7, 9, 12, 14, 16, 19, 21, 23, 27 and 29 December 2016;

·      Pit Specific Sediment Chemistry of ESC CMP Vd was undertaken on 8 December 2016;

·      Benthic Recolonisation Studies of ESC CMP IV was undertaken on 15 December 2016; and

·      Cumulative Impact Sediment Chemistry of ESC CMPs was undertaken on 20 and 22 December 2016.

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

·      Water Quality Monitoring During Capping of SB CMPs was undertaken on 6 December 2016; and

·      Benthic Recolonisation Studies of SB CMP 1 was undertaken on 13 December 2016.

1.4                              Details of Outstanding Sampling and/or Analysis

1.4.1                         No outstanding sampling remained for December 2016.

1.4.2                         A summary of field activities conducted are presented in Annex A.  The following 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 CMPs and SB CMP 1 in December 2016.

1.4.3                         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 Cumulative Impact Sediment Chemistry of ESC CMPs in December 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 52nd Monthly Progress Report:

·      Water Quality Monitoring During Dredging of ESC CMP Vb in December 2016;

·      Water Column Profiling of ESC CMP Vd in December 2016; and

·      Pit Specific Sediment Chemistry of ESC CMP Vd in November and December 2016.

1.5.2                            Impact Water Quality Monitoring during Dredging Operations of ESC CMP Vb – December 2016

1.5.3                         Water quality monitoring was conducted three times per week during the reporting period on 2, 5, 7, 9, 12, 14, 16, 19, 21, 23, 27 and 29 December 2016.  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. 

1.5.4                          Monitoring results are presented in Table B1 of Annex B.  Daily dredging volume in December 2016 is reported in Annex C.  Levels of Dissolved Oxygen (DO), Turbidity and Suspended Solid (SS) generally complied with the Action and Limit Levels (see Table B2 of Annex B for details) set in the Baseline Monitoring Report ([7]), 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 29 December 2016

1.5.6                            Water Column Profiling of ESC CMP Vd – December 2016

1.5.7                           Water Column Profiling was undertaken at a total of two sampling stations (Upstream and Downstream stations) on 1 December 2016.  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 2006 - 2015 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 (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 B2 of Annex B for details). 

In-situ Measurements

1.5.8                           Analyses of results for December 2016 indicated that levels of DO and pH complied with the WQOs at both Downstream and Upstream stations (Table B3 of Annex B).  In addition, DO and Turbidity at all stations complied with the Action and Limit Levels (Tables B2 and B3 of Annex B).

Laboratory Measurements for Suspended Solids (SS)

1.5.9                           Analyses of results for December 2016 indicated that the SS levels were higher than the WQO at both Upstream and Downstream stations.  However, both Upstream and Downstream stations complied with the Action and Limit Levels (Tables B2 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                       Pit Specific Sediment Chemistry of ESC CMP Vd – November and December 2016

1.5.12                                                                   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 in November and December 2016. 

1.5.13                                                              The concentrations of all inorganic contaminants were lower than the Lower Chemical Exceedance Level (LCEL) at all stations in November and December 2016 (Figures 1, 2, 5 and 6 of Annex D). 

1.5.14                                                                For organic contaminants, the concentrations of Total Organic Carbon (TOC) were similar amongst the stations in November and December 2016 (Figures 3 and 7 of Annex D).  Tributyltin (TBT) concentrations were higher at Active Pit station ESC-NPAA and Active Pit station ESC-NPAB in November and December 2016, respectively (Figures 4 and 8 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 November and December 2016.

1.5.15                                                               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 November and December 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                                          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 52nd Monthly Progress Report:

·                                                                Water Quality Monitoring during Capping Operations of SB CMPs in December 2016.

1.6.2                            Water Quality Monitoring during Capping of SB CMPs – December 2016

1.6.3                          The monitoring results obtained during December 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 December 2016 as shown in Figure 1.4.  Graphical presentation of the monitoring results is provided in Annex D.

In-situ Measurements

1.6.4                              Graphical presentation of the monitoring results (Temperature, DO, pH, Salinity and Turbidity) is shown in Figures 9 - 14 of Annex D.  The levels of pH at all stations in December 2016 complied with the WQO (Table B5 of Annex B; Figure 9 of Annex D).  The levels of Turbidity at all stations complied with the Action and Limit levels in December 2016 (Table B5 of Annex B; Figure 10 of Annex D).  The levels of DO at all stations complied with the WQO and the Action and Limit levels in December 2016 (Table B5 of Annex B; Figure 12 of Annex D).  The levels of Salinity at all stations complied with the WQO in December 2016 (Table B5 of Annex B; Figure 14 of Annex D).

Laboratory Measurement

1.6.5                          The concentrations of SS were higher than the WQO (13.2 mg/L for dry season) at Tai Ho Bay 1 station in December 2016 (Table B5 of Annex B; Figure 15 of Annex D).  However, levels of SS at all stations complied with the Action and Limit Levels (Table B5 of Annex B).

1.6.6                          For nutrients, concentrations of Ammonia (NH3) were relatively similar amongst all stations (Table B5 of Annex B; Figure 16 of Annex D).  The levels of Total Inorganic Nitrogen (TIN) at Tai Ho Bay 1, Tai Ho Bay 2, Sham Shui Kok and Tai Mo To stations were higher the WQO of 0.5 mg/L (Table B5 of Annex B; Figure 17 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 ([9]) and such exceedances of TIN WQO at all stations are unlikely to be caused by the capping operation at CMP 2.  Levels of 5-Day Biochemical Oxygen Demand (BOD5) were relatively similar amongst all stations (Table B5 of Annex B; Figure 18 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 December 2016.  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 January 2017 for ESC CMPs:

·      Water Column Profiling of ESC CMP Vd;

·      Routine Water Quality Monitoring of ESC CMPs;

·      Water Quality Monitoring During Dredging of ESC CMP Vb;

·      Pit Specific Sediment Chemistry of ESC CMP Vd; and

·      Demersal Trawling of ESC CMPs.

1.7.2                     No monitoring activities will be scheduled in the next monthly period of January 2017 for SB CMPs.

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

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

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