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

27th MONTHLY PROGRESS REPORT FOR NOVEMBER 2014

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 2014, the following works were being undertaken at the CMPs:

         Capping was being undertaken at ESC CMPs ;

         Disposal of contaminated mud was taking place at SB CMP 1 until 25 November 2014 and at SB CMP 2 starting from 26 November 2014; and

         Dredging operations were taking place at SB CMP 2 until 25 November 2014.

Figure 1.1 Works Schedule for ESC CMPs and SB CMPs

1.2                                      Reporting Period

1.2.1                                This 27th Monthly Progress Report covers the EM&A activities for the reporting month of November 2014.

1.3                                      Details of Sampling and Laboratory Testing Activities

1.3.1                               No monitoring activity was scheduled to be undertaken for ESC CMPs in November 2014.

1.3.2                               The following monitoring activities have been undertaken for SB CMPs in November 2014:

         Impact Water Quality Monitoring during Dredging Operations was undertaken for CMP 2 three times per week on 3, 5, 7, 10, 12, 14, 17, 19, 21 and 24 November 2014;

         Routine Water Quality Monitoring for CMP 1 was undertaken on 4 November 2014;

         Pit Specific Sediment Chemistry for CMP 1 was undertaken on 6 November 2014; and

         Water Column Profiling for CMP 1 was undertaken on 13 November 2014.

1.4                                      Details of Outstanding Sampling and/or Analysis

1.4.1                                No outstanding sampling remained for November 2014.

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

1.5                                      Brief Discussion of the Monitoring Results for SB CMPs

1.5.1                               Brief discussion of the monitoring results of the following activities for SB CMPs is presented in this 27th Monthly Progress Report:

         Pit Specific Sediment Chemistry of CMP 1 conducted in October and November 2014;

         Impact Water Quality Monitoring during Dredging Operations of CMP 2 conducted from 31 October 2014 to 24 November 2014;

         Routine Water Quality Monitoring of CMP 1 conducted in October and November 2014; and

         Water Column Profiling of CMP 1 conducted on 13 November 2014.

1.5.2                                Pit Specific Sediment Chemistry of CMP 1 October and November 2014

1.5.3                               Monitoring locations for Pit Specific Sediment Chemistry for CMP 1 are shown in Figure 1.2. A total of six (6) monitoring stations were sampled in October and November 2014.

1.5.4                               The concentrations of all inorganic contaminants were lower than the Lower Chemical Exceedance Level (LCEL) at all stations in October 2014 (Figures 1 and 2 of Annex B) and November 2014 (Figures 6 and 7 of Annex B).

1.5.5                               For organic contaminants, the concentrations of Total Organic Carbon (TOC) were similar amongst stations in October and November 2014 (Figures 3 and 8 of Annex B). Tributyltin (TBTs) were observed to be higher at Near Pit station SB-NNAB and at Active Pit station SB-NPAB in October and November 2014, respectively (Figures 4 and 9 of Annex B). High Molecular Weight Polycyclic Aromatic Hydrocarbons (MW PAHs) were above limit of reporting at Active Pit stations SB-NPAA and SB-NPAB in October and November 2014 (Figures 5 and 10 of Annex B) Low MW PAHs, 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 October and November 2014.

1.5.6                               As higher TOC, TBTs and High MW PAHs concentrations were generally recorded within the Active Pit stations only which were receiving contaminated mud during the reporting months, there is no evidence indicating any dispersal of contaminants from the active pit to nearby sensitive receivers.

1.5.7                               Overall, there is no evidence indicating any unacceptable environmental impacts to sediment quality as a result of the contaminated mud disposal operations at CMP 1 in October and November 2014.

1.5.8                                Impact Water Quality Monitoring during Dredging Operations of CMP 2 31 October to 24 November 2014

1.5.9                                Impact Water Quality Monitoring during Dredging Operations of CMP 2 was conducted three times per week from 31 October to 24 November 2014 during the reporting period. 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 of the dredging operations at CMP 2. Monitoring was also conducted at five Sensitive Receiver Stations situated in Ma Wan, Shum Shui Kok, Tai Mo To and Tai Ho Bay. A total of twelve (12) stations were monitored and locations of the sampling stations are shown in Figure 1.3.

1.5.10                            Monitoring results are presented in Table C1 of Annex C. Daily dredging volume in October and November 2014 is reported in Annex D. Levels of Dissolved Oxygen (DO), Turbidity and Suspended Solids (SS) generally complied with the Action and Limit Levels (see Table C2 of Annex C for details) set in the Baseline Monitoring Report ([7]), except for the following occasion of exceedances discussed in Table 1.1 below.

1.5.11                            As presented in Table 1.1, the results indicated that the dredging operations at CMP 2 did not appear to cause any unacceptable deterioration in water quality during this reporting period. Therefore, no further mitigation measures, except for those recommended in the Environmental Permit (EP-427/2011/A), are considered necessary for the dredging operations.

Table 1.1 Details of Exceedances Recorded at CMP 2 between 31 October and 24 November 2014

Date

Tide

Parameter

Station

Type

Remarks

3 November 2014

Mid-Flood

Turbidity

DS3

Limit

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

    Stations DS2, DS3 and DS4 are located further away from the works area of CMP 2 when compared to station DS1 at which the levels of Turbidity and SS did not exceed the Action and Limit Levels during the same tidal period.

 

3 November 2014

Mid-Flood

SS

DS2

Action

3 November 2014

Mid-Flood

SS

DS3

Action

5 November 2014

Mid-Ebb

Turbidity

DS4

Action

 

 

 

 

 


1.5.12                            Routine Water Quality Monitoring of CMP 1 October and November 2014

1.5.13                           Routine Water Quality Monitoring were undertaken on 14 October and 4 November 2014 at a total of fourteen (14) sampling stations as shown in Figure 1.4. The water quality monitoring results 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 wet season period (April to October) and dry season period (November to March) of 2004-2013 from stations in the North Western Water Control Zone (WCZ), where CMP is located. Levels of DO, Turbidity and SS were also assessed for compliance with the Action and Limit Levels (see Table C2 of Annex C for details). The monitoring results are shown in Figures 11-30 of Annex B and Tables C3-C4 of Annex C.

In-situ Measurements

1.5.14                           Analyses of results for October and November 2014 indicated that the levels of pH, DO and Salinity complied with the WQOs at all stations (Impact, Intermediate, Reference and Water Sensitive Receiver stations) (Figures 11-14 and 21-24 of Annex B; Table C3 of Annex C).

1.5.15                           The levels of DO and Turbidity complied with the Action and Limit Levels at all stations in October and November 2014 (Figures 12, 15, 22 and 25 of Annex B; Table C3 of Annex C).

Laboratory Measurements

1.5.16                            Laboratory analysis of October and November 2014 results indicated that concentrations of Mercury and Silver were below their limit of reporting at all stations. Arsenic, Cadmium, Chromium, Copper, Lead, Nickel and Zinc were detected in samples from most stations (Figures 16-17 and 26-27 of Annex B; Table C4 of Annex C). Detailed statistical analysis will be presented in the Quarterly Report to observe any spatial and temporal trends.

1.5.17                            For nutrients, concentrations of Total Inorganic Nitrogen (TIN) at all stations in October and November 2014 monitoring complied with the WQO of 0.5mg/L (Figures 18 and 28 of Annex B). Ammonia Nitrogen (NH3-N) concentration was relatively similar amongst all stations (Figures 18 and 28 of Annex B). Level of 5-day Biochemical Oxygen Demand (BOD5) was similar amongst stations (Figures 19 and 29 of Annex B).

1.5.18                            Concentrations of SS exceeded the WQO (11.6 mg/L for wet season; 13.8 mg/L for dry season) at Reference, Tai Mo To and Tai Ho Bay 1 stations in October and November 2014. However, SS at all stations complied with the Action and Limit Levels in October and November 2014 (Figures 20 and 30 of Annex B; Table C4 of Annex C).

1.5.19                            Overall, results of the Routine Water Quality Monitoring indicated that the disposal operation at CMP 1 did not appear to cause any unacceptable deterioration in water quality in October and November 2014.

1.5.20                            Water Column Profiling of CMP 1 November 2014

1.5.21                           Water Column Profiling was undertaken at a total of two sampling stations (Upstream and Downstream stations) on 13 November 2014. The water quality monitoring results have been assessed for compliance with the WQO as discussed in Section 1.5.13. The monitoring results were also compared with the Action and Limit Levels set in Baseline Monitoring Report (see Table C2 of Annex C for details).

In-situ Measurements

1.5.22                           Analyses of results for November 2014 indicated that levels of Salinity, turbidity, DO and pH complied with the WQOs at both Downstream and Upstream stations (Table C5 of Annex C).

Laboratory Measurements for SS

1.5.23                           Analyses of results for November 2014 indicated that the SS levels at both Upstream and Downstream stations complied with the WQO. SS levels at all stations complied with the Action and Limit Levels (Table C5 of Annex C).

1.5.24                           Overall, the monitoring results indicated that the mud disposal operation at CMP 1 did not appear to cause any deterioration in water quality during this reporting period.

1.6                                      Activities Scheduled for the Next Month

1.6.1                               The following monitoring activities will be conducted in the next monthly period of December 2014 for SB CMPs:

         Pit Specific Sediment Chemistry of CMP 2;

         Cumulative Impact Sediment Chemistry of CMP 2;

         Water Column Profiling of CMP 2; and

         Water Quality Monitoring during Capping Operations of CMP 1.

1.6.2                                The following monitoring activities will be conducted in the next monthly period of December 2014 for ESC CMPs:

         Water Quality Monitoring during Capping Operations of ESC CMPs; and

         Benthic Recolonisation Studies of ESC CMPs.

1.6.3                                The sampling schedule is presented in Annex A.

1.7                                      Study Programme

1.7.1                                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 (2012) Baseline Monitoring Report.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 October 2012.