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

39th MONTHLY PROGRESS REPORT FOR November 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 November 2015, the following works were being undertaken at the CMPs:

       Dredging operation at ESC CMP Vd;

       Capping operations at ESC CMP Va; 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 39th Monthly Progress Report covers the EM&A activities for the reporting month of November 2015.

1.3                                      Details of Sampling and Laboratory Testing Activities

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

       Impact Water Quality Monitoring during Dredging Operations of ESC CMPs was undertaken on 13, 16, 18 and 20 November 2015.

 

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

       Pit Specific Sediment Chemistry of CMP 2 was undertaken on 3 November 2015;

       Water Column Profiling of CMP 2 was undertaken on 5 November 2015; and

       Routine Water Quality Monitoring of CMP 2 was undertaken on 12 November 2015.

1.4                                      Details of Outstanding Sampling and/or Analysis

1.4.1                                No outstanding sampling remained for November 2015.

1.4.2                                A summary of field activities conducted are presented in Annex A. 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 Pit Specific Sediment Chemistry of SB CMP 2 in November 2015.

 

1.5                                      Brief Discussion of the Monitoring Results for ESC CMPs

1.5.1                               Brief discussion of the monitoring results of the Impact Water Quality Monitoring during Dredging Operations of ESC CMP Vd conducted in November 2015 is presented below.

1.5.2                                                                               Impact Water Quality Monitoring during Dredging Operations of ESC CMP Vd November 2015

1.5.3                                Dredging activities were carried out on 13 and 14 November 2015 during this reporting period. As such, Impact Water Quality Monitoring during Dredging Operations of ESC CMP Vd was conducted three times per week from 13 to 20 November 2015 to monitor water quality around the CMP during dredging activities. On 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 Vd. 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 November 2015 is reported in Annex C. Levels of Dissolved Oxygen (DO), Turbidity and Suspended Solid (SS) complied with the Action and Limit Levels (see Table B2 of Annex B for details) set in the Baseline Monitoring Report ([7]).

1.5.5                                The results indicated that the dredging operations at ESC CMP Vd 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                                      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 39th Monthly Progress Report:

       Pit Specific Sediment Chemistry of CMP 2 in October 2015;

       Routine Water Quality Monitoring of CMP 2 in November 2015; and

       Water Column Profiling of CMP 2 in November 2015.

1.6.2                                    Pit Specific Sediment Chemistry of CMP 2 October 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 October 2015.

1.6.4                                                                               The concentrations of most inorganic contaminants (Arsenic, Cadmium, Chromium, Lead, Nickel and Zinc) were lower than the Lower Chemical Exceedance Level (LCEL) at all stations, except Copper, Mercury and Silver (Figures 1 and 2 of Annex D). Copper exceeded the LCEL at Active Pit stations SB-NPBA (Figure 1 of Annex D) while Silver exceeded the LCEL at both Active Pit stations SB-NPBA and SB-NPBB (Figure 2 of Annex D). In addition, mercury exceeds LCEL at Near Pit Stations SB-NNBA and SB-NNBB and Pit-edge Station SB-NEBA (Figure 2 of Annex D).

1.6.5                                                                               Higher Copper and Silver concentrations were recorded within the Active Pit stations only which were receiving contaminated mud during the reporting month whilst higher Mercury concentrations were only recorded at Near Pit stations and Pit-edge Station. Therefore, there is no evidence indicating any dispersal of contaminants from the Active Pit due to the disposal activities.

1.6.6                                                                               For organic contaminants, the concentrations of Total Organic Carbon (TOC) were similar at all stations (Figure 3 of Annex D). Tributyltin (TBT) concentrations were observed to be higher at Active Pit station SB-NPBA (Figure 4 of Annex D). Low and High Molecular Weight Polycyclic Aromatic Hydrocarbons (PAHs), Total Polychlorinated Biphenyls (PCBs), 4,4-dichlorodiphenyldichloroethylene (DDE) and Total dichlorodiphenyltrichloroethane (DDT) concentrations were below the limit of reporting at most stations, except High Molecular Weight PAHs at Active Pit stations SB-NPBA and SB-NPBB (Figure 5 of Annex D).

 

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 October 2015. 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.

1.6.8                                Routine Water Quality Monitoring of SB CMP 2 November 2015

1.6.9                                                                               The monitoring results for the Routine Water Quality Monitoring conducted in November 2015 in the dry season 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 2005 - 2014 from stations in the Northwestern Water Control Zone (WCZ), where the CMPs are located ([8]). For Salinity, the averaged value obtained from the Reference stations 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 B3 of Annex B for details). The monitoring results are shown in Figures 6-16 of Annex D and Tables B4 and B5 of Annex B. A total of fourteen (14) monitoring stations were sampled in November 2015 as shown in Figure 1.4.

1.6.10                                                                           In-situ Measurements

1.6.11                                                                           Graphical presentation of the monitoring results (Temperature, DO, pH, Salinity and Turbidity) is shown in Figures 6 -11 of Annex D. Analyses of results for November 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 November 2015 (Figures 6 8, 10 of Annex D).

1.6.12                                                                           The levels of DO and Turbidity complied with the Action and Limit Levels at all stations (Table B4 of Annex B; Figures 8 and 11 of Annex D).

1.6.13                            Overall, in-situ measurement results of the Routine Water Quality Monitoring indicated that the disposal operation at CMP 2 did not appear to cause any unacceptable impacts in water quality in November 2015.

Laboratory Measurements

1.6.14                            Laboratory analysis of November 2015 results indicated that concentrations of Cadmium, Silver and Mercury were below their limit of reporting at all stations. Arsenic, Chromium, Copper, Lead, Nickel and Zinc were detected in November 2015 samples and the concentrations were similar amongst stations (Figures 12 & 13 of Annex D). Results of laboratory analysis were shown in Table B5 of Annex B.

1.6.15                            For nutrients, concentrations of Total Inorganic Nitrogen (TIN) at Intermediate stations in November 2015 exceeded the WQO (0.5 mg/L) (Figure 14 of Annex D). Ammonia Nitrogen (NH3-N) concentration was relatively similar amongst all stations (Figure 14 of Annex D). Levels of 5-day Biochemical Oxygen Demand (BOD5) appear to be higher at Shum Shui Kok and Tai Mo To stations in November 2015 (Figure 15 of Annex D).

1.6.16                            Concentrations of SS exceeded the WQO (13.5 mg/L for dry season) at Reference and Sham Shui Kok stations in November 2015. Concentrations of SS also exceeded the Action Levels at Sham Shui Kok while it complied with the Action and Limit Levels at all other stations in November 2015 (Figure 16 of Annex D; Table B5 of Annex B). Since Sham Shui Kok station is located further away from Impact stations where exceedances of Action and Limit Levels did not occur, the exceedance of SS level was unlikely to be caused by mud disposal works at CMP 2 and it is considered to be sporadic events and characteristic of water quality in this area of Hong Kong.

1.6.17                            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 November 2015. Detailed statistical analysis will be presented in the Quarterly Report to investigate any spatial and temporal trends of potential concern.

 

1.6.18                            Water Column Profiling of CMP 2 November 2015

1.6.19                            Water Column Profiling was undertaken at a total of two sampling stations (Upstream and Downstream stations) on 5 November 2015. The monitoring results have been assessed for compliance with the WQOs (see Section 1.6.9 for details).

1.6.20                            In-situ Measurements

1.6.21                            Analyses of results for November 2015 indicated that levels of Salinity, DO and pH complied with the WQOs at both Downstream and Upstream stations (Table B6 of Annex B). In addition, DO and Turbidity at all stations complied with the Action and Limit Levels (Tables B3 and B6 of Annex B).

1.6.22                            Laboratory Measurements for SS

1.6.23                            Analyses of results for November 2015 indicated that the SS levels complied with the WQO at Downstream stations. Both Upstream and Downstream stations complied with the Action and Limit Levels (Tables B3 and B6 of Annex B).

1.6.24                            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.


 

1.7                                      Activities Scheduled for the Next Month

1.7.1                               The following monitoring activities will be conducted in the next monthly period of December 2015 for SB CMPs:

       Pit Specific Sediment Chemistry of CMP 2;

       Cumulative Impact Sediment Chemistry of SB CMPs;

       Water Column Profiling of CMP 2;

       Water Quality Monitoring During Capping of CMP 1; and

       Benthic Recolonisation Studies of CMP 1.

1.7.2                               The following monitoring activities will be conducted in the next monthly period of December 2015 for ESC CMPs:

       Impact Water Quality Monitoring during Dredging Operations of CMP Vd

       Benthic Recolonisation Studies of CMP IV; and

       Water Quality Monitoring During Capping of 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 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 (2009). Draft Second Review of the EM&A Manual. Under Agreement No. CE 4/2009 (EP) EM&A for Contaminated Mud Pit at Sha Chau (2009-2013) Investigation

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