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

44th MONTHLY PROGRESS REPORT FOR April 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-427/2011A) 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 April 2016, the following works were being undertaken at the CMPs:

       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 44th Monthly Progress Report covers the EM&A activities for the reporting month of April 2016.

1.3                                      Details of Sampling and Laboratory Testing Activities

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

       Routine Water Quality Monitoring of ESC CMP Vd was undertaken on 5 April 2016;

       Water Column Profiling of ESC CMP Vd was undertaken on 6 April 2016; and

       Pit Specific Sediment Chemistry of ESC CMP Vd was undertaken on 7 April 2016.

1.3.2                                No monitoring activities were scheduled to be undertaken for SB CMPs in April 2016.

1.4                                      Details of Outstanding Sampling and/or Analysis

1.4.1                                No outstanding sampling and analysis remained for April 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 44th Monthly Progress Report:

       Routine Water Quality Monitoring of ESC CMP Vd in April 2016;

       Water Column Profiling of ESC CMP Vd in April 2016; and

       Pit Specific Sediment Chemistry of ESC CMP Vd in March and April 2016.

1.5.2                                Pit Specific Sediment Chemistry of ESC CMP Vd March and April 2016

1.5.3                                                                               Monitoring locations for Pit Specific Sediment Chemistry for ESC CMP Vd are shown in Figure 1.2. A total of six (6) monitoring stations were sampled in March and April 2016.

1.5.4                                                                               The concentrations of most inorganic contaminants were lower than the Lower Chemical Exceedance Level (LCEL) at all stations, except Mercury (Figures 1, 2, 5 and 6 of Annex C). In March 2016, Mercury exceeded the LCEL at all stations except Near Pit station ESC-NNBA (Figure 2 and 6 of Annex C). In April 2016, Mercury exceeded the LCEL at all stations except Active Pit station ESC-NPBB (Figures 2 and 6 of Annex C). Since Mercury concentrations were recorded to be similar amongst all stations, the exceedances of the LCEL at those stations are unlikely to be caused by the disposal operation at ESC CMP Vd.

1.5.5                                                                               For organic contaminants, the concentrations of Total Organic Carbon (TOC) were similar amongst most stations and it was observed to be lower at Near Pit station ESC-NNBA in March 2016 (Figures 3 and 7 of Annex C). In March 2016, Tributyltin (TBT) concentrations were observed to be lower at Pit Edge station ESC-NEBB (Figure 4 of Annex C). In April 2016, Tributyltin (TBT) concentrations were observed to be higher at Near Pit station ESC-NNBA and Pit Edge stations ESC-NEBA (Figure 8 of Annex C). Low and High Molecular Weight Polycyclic Aromatic Hydrocarbons (PAHs), Total Polychlorinated Biphenyls (PCBs), Total dichlorodiphenyltrichloroethane (DDT) and 4,4-dichlorodiphenyldichloroethylene (DDE) concentrations were below the limit of reporting at all stations in March and April 2016.

1.5.6                                                                               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 March and April 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.

1.5.7                                                                                Water Column Profiling of ESC CMP Vd April 2016

1.5.8                                Water Column Profiling was undertaken on 6 April 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 wet season period (April to October) of 2005 - 2014 from stations in the Northwestern Water Control Zone (WCZ), where the ESC CMPs are located ([7]). 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 B1 of Annex B for details).

In-situ Measurements

1.5.9                                Analyses of results for April 2016 indicated that levels of Salinity, 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 (Table B2 of Annex B).

Laboratory Measurements for Suspended Solids (SS)

1.5.10                            Analyses of results for April 2016 indicated that the SS levels complied with the WQO and the Action and Limit Levels at both Upstream and Downstream stations (Table B2 of Annex B).

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 Vd April 2016

1.5.12                            Routine Water Quality Monitoring was undertaken on 5 April 2016. The monitoring results have been assessed for compliance with the WQOs (see Section 1.5.8 for details). Levels of DO and Turbidity were also assessed for compliance with the Action and Limit Levels (see Table B1 of Annex B for details). The monitoring results are shown in Tables B3 and B4 of Annex B and Figures 9 - 14 of Annex C. A total of ten (10) monitoring stations were sampled in April 2016 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 9 - 14 of Annex C. Analyses of results for April 2016 indicated that the levels of pH and DO complied with the WQOs at all stations (Impact, Intermediate, Reference and Water Sensitive Receiver stations) in April 2016 (Table B3 of Annex B; Figures 11 and 14 of Annex C). Levels of Salinity at most stations also complied with WQO, except for Ma Wan station (Table B3 of Annex B; Figure 13 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.

1.5.14                                The levels of DO and Turbidity complied with the Action and Limit Levels at all stations (Table B3 of Annex B; Figures 11 and 14 of Annex C).

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 April 2016.

Laboratory Measurements

1.5.16                                Laboratory analysis of April 2016 results indicated that concentrations of Cadmium, Chromium, Lead, Silver and Mercury were below their limit of reporting at all stations. Arsenic, Copper, Zinc and Nickel were detected in April 2016 samples and the concentrations were similar amongst stations (Table B4 of Annex B; Figure 15 of Annex C).

1.5.17                                For nutrients, concentrations of Total Inorganic Nitrogen (TIN) at Impact, Intermediate and Reference stations in April 2016 exceeded the WQO (0.5 mg/L) (Table B4 of Annex B; Figure 16 of Annex C). It should be noted that due to effect of Pearl River, the North Western WCZ has historically experienced higher levels of TIN ([8]). Since TIN concentrations were recorded to be similar amongst all stations, the exceedances of TIN WQO at all 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 (Table B4 of Annex B; Figure 16 of Annex C). Levels of 5-day Biochemical Oxygen Demand (BOD5) appear to be higher at Ma Wan station in April 2016 (Table B4 of Annex B; Figure 17 of Annex C).

1.5.18                                Concentrations of SS complied with the WQO (11.1 mg/L for wet season), except in Reference stations. Concentrations of SS complied with the Action and Limit Levels at all stations in April 2016 (Table B4 of Annex B; Figure 18 of Annex C).

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 April 2016. 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 44th Monthly Progress Report:

       Pit Specific Sediment Chemistry of CMP 2 in March 2016.

1.6.2                                Pit Specific Sediment Chemistry of CMP 2 March 2016

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 March 2016.

1.6.4                                                                               The concentrations of most inorganic contaminants were lower than the LCEL at all stations, except Mercury and Silver (Figures 20 of Annex C) in March 2016. Mercury and Silver exceeded the LCEL at Active Pit stations SB-NPBB and SB-NPBA, respectively (Figure 20 of Annex C).

1.6.5                                                                               For organic contaminants, the concentrations of TOC were similar amongst most stations and it was observed to be lower at Pit Edge station SB-NEBB and Active Pit station SB-NPBB in March 2016 (Figure 21 of Annex C). TBT concentrations were observed to be higher at Active Pit station SB-NPBA and Near Pit station SB-NNBA (Figure 22 of Annex C). Low and High Molecular Weight PAHs, Total PCBs, Total DDT and 4,4-DDE concentrations were below the limit of reporting at all stations in March 2016.

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 SB CMP 2 in March 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.


 

1.7                                      Activities Scheduled for the Next Month

1.7.1        No monitoring activities will be scheduled in the next monthly period of May 2016 for SB CMPs.

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

       Routine Water Quality Monitoring of ESC CMP Vd;

       Pit Specific Sediment Chemistry of ESC CMP Vd; and

       Water Column Profiling of ESC 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 D.

 


 


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

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