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

30th MONTHLY PROGRESS REPORT FOR February 2015

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 February 2015, the following works were being undertaken at the CMPs:

       Capping operations at ESC CMPs;

       Capping operations at SB CMP 1; and

       Disposal of contaminated mud at SB CMP 2.

Figure 1.1 Works Schedule for ESC CMPs and SB CMPs

1.2                                      Reporting Period

1.2.1                                This 30th Monthly Progress Report covers the EM&A activities for the reporting month of February 2015.

1.3                                      Details of Sampling and Laboratory Testing Activities

1.3.1                                                                               The following monitoring activities have been undertaken for ESC CMPs in February 2015:

       Water Quality Monitoring during Capping was undertaken for ESC CMPs on 5 February 2015.

1.3.2                                                                               The following monitoring activities have been undertaken for SB CMPs in February 2015:

       Water Column Profiling for CMP 2 was undertaken on 2 February 2015;

       Pit Specific Sediment Chemistry for CMP 2 was undertaken on 3 February 2015;

       Water Quality Monitoring during Capping was undertaken for CMP 1 on 5 February 2015;

       Cumulative Impact Sediment Chemistry for CMP 2 was undertaken from 9 to 11 February 2015;

       Sediment Toxicity Tests for CMP 2 was undertaken from 9 to 11 February 2015;

       Routine Water Quality Monitoring for CMP 2 was undertaken on 12 February 2015; and

       Demersal Trawling for CMP 2 was undertaken on 25 and 26 February 2015.

1.4                                      Details of Outstanding Sampling and/or Analysis

1.4.1                                No outstanding sampling remained for February 2015. The following laboratory analyses were still in progress during the preparation of this monthly report and hence are not presented in this monthly report:

      Laboratory analyses of sediment samples collected for Cumulative Impact Sediment Chemistry of CMP 2 in February 2015;

      Laboratory analyses of sediment samples collected for Sediment Toxicity Tests of CMP 2 in February 2015; and

      Identification of Catch from Demersal Trawling of CMP 2 and subsequent chemical analysis for the biota samples in January and February 2015.

1.4.2                                A summary of field activities conducted are presented in Annex A.

 

1.5                                      Brief Discussion of the Monitoring Results for ESC CMPs

1.5.1                                    Brief discussion of the monitoring results of the Water Quality Monitoring during Capping of ESC CMPs conducted on 5 February 2015 is presented below.

1.5.2                                Water Quality Monitoring during Capping February 2015

1.5.3                                The monitoring results obtained during February 2015 sampling in the dry season have been assessed for compliance with the Water Quality Objectives (WQOs) through a review of the Environmental Protection Department (EPD) routine water quality monitoring data for the dry season period (November to March) of 2004 2013 from stations in the North Western Water Control Zone (WCZ), where ESC CMPs are located. For Salinity, the average value obtained from the Reference stations was used for the basis as the WQO. A total of sixteen (16) monitoring stations were sampled in February 2015 as shown in Figure 1.2. Graphical presentation of the monitoring results is provided in Annex B.

In-situ Measurements

1.5.4                                Graphical presentation of the monitoring results is shown in Figures 1-6 of Annex B. Levels of Dissolved Oxygen (DO), pH and Salinity at all stations in February 2015 complied with the WQO.

Laboratory Measurements for Suspended Solids (SS)

1.5.5                                Concentrations of SS complied with the WQO at all stations in February 2015 (Figure 7 of Annex B). Further statistical analysis will be undertaken in the quarterly report to investigate whether the capping operations at ESC CMPs is causing any unacceptable deterioration in water quality of the area.

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 30th Monthly Progress Report:

       Pit Specific Sediment Chemistry of CMP 2 conducted in January and February 2015;

       Routine Water Quality Monitoring of CMP 2 conducted in January (laboratory measurements) and February 2015;

       Water Column Profiling of CMP 2 conducted on 2 February 2015; and

       Water Quality Monitoring during Capping for CMP 1 conducted on 5 February 2015.

 

1.6.2                                Pit Specific Sediment Chemistry of CMP 2 January and February 2015

1.6.3                                                                               Monitoring locations for Pit Specific Sediment Chemistry for CMP 2 are shown in Figure 1.3. A total of six (6) monitoring stations were sampled in January and February 2015.

1.6.4                                                                               The concentrations of most inorganic contaminants were lower than the Lower Chemical Exceedance Level (LCEL) except for Copper and Silver concentrations at Active Pit station SB-NPBB in January and February 2015 (Figures 8-9 and 13-14 of Annex B). Copper and Silver concentrations at Active Pit station SB-NPBB exceeded the LCEL and Upper Chemical Exceedance Level (UCEL) in both January and February 2015. As higher Copper and Silver concentrations were recorded within the Active Pit station only which were receiving contaminated mud during the reporting month, there is no evidence indicating any dispersal of contaminants from the active pit.

1.6.5                                                                               For organic contaminants, the concentrations of Total Organic Carbon (TOC) were similar amongst stations in January 2015, while concentrations at Active Pit Station SB-NPBB were observed to be higher in February 2015 (Figure 10 and 15 of Annex B). Tributyltin (TBTs) concentrations were observed to be higher at Active Pit station SB-NPBB in both January and February 2015 (Figures 11 and 16 of Annex B). Low Molecular Weight Polycyclic Aromatic Hydrocarbons (Low MW PAHs) and High MW PAHs were generally below the limit of reporting at most stations except for Active Pit Station SB-NPBB in January 2015, Near Pit Station SB-NNBA and Pit Edge Station SB-NEBB in February 2015. Low MW PAHs and High MW PAHs were all below the LCEL at all stations in both months. Total Dichloro-Diphenyl-Trichloroethane (DDT), 4,4-Dichloro-Diphenyl-Dichloroethylene (4,4-DDE) and Total Polychlorinated Biphenyls (PCBs) were recorded below the limit of reporting at all stations in both January 2015 and February 2015.

1.6.6                                                                               As higher TOC and TBTs concentrations were recorded within the Active Pit station only which was receiving contaminated mud during the reporting month, there is no evidence indicating any dispersal of contaminants from the active pit.

1.6.7                                                                               Overall, there is no evidence indicating any unacceptable environmental impacts to sediment quality as a result of the contaminated mud disposal operations at CMP 2 in January and February 2015. Statistical analysis will be undertaken in the quarterly report to investigate whether there are any unacceptable impacts in the area caused by the contaminated mud disposal.

1.6.8                               Routine Water Quality Monitoring of SB CMP 2 January and February 2015

1.6.9                                The monitoring results for the Routine Water Quality Monitoring conducted in January and February 2015 in the dry season have been assessed for compliance with the Water Quality Objectives (WQOs) set by EPD as discussed in Section 1.5.3. Levels of DO, Turbidity and SS were also assessed for compliance with the Action and Limit Levels (see Table C1 of Annex C for details). The monitoring results are shown in Figures 6-10 of Annex B and Table C2 of Annex C. A total of fourteen (14) monitoring stations were sampled in January and February 2015 as shown in Figure 1.4.

In-situ Measurements

1.6.10                                                                           Analyses of in-situ measurements for January 2015 were presented in the 29th Monthly Progress Report.

1.6.11                                                                           Analyses of results for February 2015 indicated that the levels of pH, DO and Salinity complied with the WQOs at all stations (Impact, Intermediate, Reference and Water Sensitive Receiver stations) in February 2015 (Figure 23-26 of Annex B).

1.6.12                                                                           The levels of DO and Turbidity complied with the Action and Limit Levels at all stations (Figures 24 and 27 of Annex B; Table C1 and C2 of Annex C).

Laboratory Measurements

1.6.13                            Laboratory analysis of January and February 2015 results indicated that concentrations of Cadmium, Mercury and Silver were below their limit of reporting at all stations. The concentrations of Chromium and Lead in half of the samples were below their limit for reporting in both months. Arsenic, Copper, Nickel and Zinc were detected in samples from most stations in January and February 2015 (Figures 18-19 and 28-29 of Annex B). Results of laboratory analysis were shown in Table C3 of Annex C. Detailed statistical analysis will be presented in the Quarterly Report to observe any spatial and temporal trends.

 

1.6.14                            For nutrients, concentrations of Total Inorganic Nitrogen (TIN) at Tai Ho Bay 2 in January 2015 and most stations (except Intermediate and Ma Wan Stations) in February 2015 exceeded the WQO (0.5mg/L) (Figure 20 and 30 of Annex B). 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]) . Therefore, the exceedances of TIN WQO at all stations are unlikely to be caused by the disposal operation at CMP 2. Ammonia Nitrogen (NH3-N) concentration was relatively similar amongst all stations (Figure 20 and 30 of Annex B). Level of 5-day Biochemical Oxygen Demand (BOD5) appear to be higher at Tai Ho Bay station 1 in January 2015 and at Shum Shui Kok and Tai Mo To stations in February 2015 (Figure 21 and 31 of Annex B).

1.6.15                            Concentrations of SS exceeded the WQO (13.7 mg/L for dry season) at Tai Ho Bay station 1 in January 2015 while complied with the WQO at all stations in February 2015. SS at all stations complied with the Action and Limit Levels in January and February 2015 (Figure 22 and 32 of Annex B; Table C2 of Annex C).

1.6.16                            Overall, results of the Routine Water Quality Monitoring indicated that the disposal operation at CMP 2 did not appear to cause any unacceptable deterioration in water quality in January and February 2015.

1.6.17                            Water Column Profiling of CMP 2 February 2015

1.6.18                                                                           Water Column Profiling was undertaken at a total of two sampling stations (Upstream and Downstream stations) on 2 February 2015. The water quality monitoring results have been assessed for compliance with the WQOs as discussed in Section 1.5.3. The monitoring results were also compared with the Action and Limit Levels set in Baseline Monitoring Report (see Table C1 of Annex C for details).

In-situ Measurements

1.6.19                                                                           Analyses of results for February 2015 indicated that levels of Salinity, DO and pH complied with the WQOs at both Downstream and Upstream stations (Table C4 of Annex C). DO and Turbidity at all stations complied with the Action and Limit Levels (Table C1 and C4 of Annex C).

Laboratory Measurements for SS

1.6.20                                                                           Analyses of results for February 2015 indicated that the SS levels at both Upstream and Downstream stations complied with the WQO. SS levels at all stations also complied with the Action and Limit Levels (Tables C1 and C3 of Annex C).

1.6.21                                                                           Overall, the monitoring results indicated that the mud disposal operation at CMP 2 did not appear to cause any deterioration in water quality during this reporting period.

1.6.22                            Water Quality Monitoring during Capping Operations of CMP 1 February 2015

1.6.23                            The monitoring results obtained during February 2015 sampling in the dry season have been assessed for compliance with the WQOs (see Section 1.5.3 for details). A total of fourteen (14) monitoring stations were sampled in February 2015 as shown in Figure 1.4. Graphical presentation of the monitoring results is provided in Annex B.

In-situ Measurements

1.6.24                            Graphical presentation of the monitoring results is shown in Figures 33-38 of Annex B. Levels of DO, pH and Salinity at all stations in February 2015 complied with the WQO.

Laboratory Measurements

1.6.25                            Concentrations of SS complied with the WQO at all stations in February 2015 (Figure 39 of Annex B).

1.6.26                            For nutrients, concentrations of Ammonia (NH3) were similar amongst all stations (Figures 40 of Annex B). Concentrations of Biochemical Oxygen Demand (BOD5) were similar at Impact, Intermediate and Reference stations, but slightly higher than other stations in February 2015. Total Inorganic Nitrogen (TIN) at all stations exceeded the WQO of 0.5 mg/L in February 2015 (Figure 42 of Annex B). As discussed in Section 1.6.14, the North Western WCZ has historically experienced higher levels of TIN and the exceedances of TIN WQO at all stations are unlikely to be caused by the capping operation at CMP 1.

1.6.27                            Since higher BOD5 was recorded for both Impact and Reference stations, the higher concentration is likely due to the natural fluctuation of BOD5 in the environment. Therefore, there is no evidence indicating any degradation for water quality due to the capping activities at CMP 1.

1.6.28                            Statistical analysis will be undertaken in the quarterly report to investigate whether the capping operations at CMP 1 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 March 2015 for SB CMPs:

       Pit Specific Sediment Chemistry of CMP 2; and

       Water Column Profiling of CMP 2.

1.7.2                                No monitoring activities will be conducted in the next monthly period of March 2015 for ESC 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 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://www.epd.gov.hk/epd/misc/marine_quality/1986-2005/textonly/eng/index.htm