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

49th MONTHLY PROGRESS REPORT FOR September 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 September 2016, the following works were being undertaken:

       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 49th Monthly Progress Report covers the EM&A activities for the reporting month of September 2016.

1.3                                      Details of Sampling and Laboratory Testing Activities

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

       Pit Specific Sediment Chemistry of ESC CMP Vd was undertaken on 1 September 2016; and

       Water Column Profiling of ESC CMP Vd was undertaken on 2 September 2016.

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

1.4                                      Details of Outstanding Sampling and/or Analysis

1.4.1                                No outstanding sampling and analysis remained for September 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 49th Monthly Progress Report:

       Water Column Profiling of ESC CMP Vd in September 2016;

       Pit Specific Sediment Chemistry of ESC CMP Vd in August and September 2016; and

       Cumulative Impact Sediment Chemistry of ESC CMPs in August 2016.

1.5.2                                Water Column Profiling of ESC CMP Vd September 2016

1.5.3                                Water Column Profiling was undertaken at a total of two sampling stations (Upstream and Downstream stations) on 1 September 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 2006 - 2015 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

1.5.4                                Analyses of results for September 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 B1 of Annex B).

Laboratory Measurements for Suspended Solids (SS)

1.5.5                                Analyses of results for September 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 (Table B1 of Annex B).

1.5.6                                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.

1.5.7                                Pit Specific Sediment Chemistry of ESC CMP Vd August and September 2016

1.5.8                                                                               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 August and September 2016.

1.5.9                                                                               The concentrations of all inorganic contaminants were lower than the Lower Chemical Exceedance Level (LCEL) at all stations in August and September 2016 (Figures 1, 2, 5 and 6 of Annex C).

1.5.10                                                                           For organic contaminants, the concentrations of Total Organic Carbon (TOC) were similar amongst the stations in August and September 2016 (Figures 3 and 7 of Annex C). In August 2016, Tributyltin (TBT) concentrations were higher at Active Pit station ESC-NPAB and Pit Edge station ESC-NEAA whilst TBT concentrations were higher at Active Pit ESC-NPAA station in September 2016 (Figures 4 and 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 August and September 2016.

1.5.11                                                                           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 August and September 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.

 

1.5.12                            Cumulative Impact Sediment Chemistry of ESC CMPs August 2016

1.5.13                                                                           Monitoring locations for Cumulative Impact Sediment Chemistry for ESC CMPs are shown in Figure 1.3. A total of nine (9) monitoring stations were sampled in August 2016.

1.5.14                            Analyses of results for the Cumulative Impact Sediment Chemistry Monitoring indicated that the concentrations of all inorganic contaminants were below the LCEL in August 2016 (Figures 9 and 10 of Annex C).

1.5.15                            For organic contaminants, concentrations of TOC were observed to be similar among all stations (Figure 11 of Annex C). Concentrations of TBTs were recorded to be higher at Ma Wan station and Capped Pit station ESC-RCA (Figure 12 of Annex C). Total DDT, 4,4-DDE, Total PCBs as well as Low and High Molecular Weight PAHs were recorded below the limit of reporting at all stations.

1.5.16                            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 August 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                                      Activities Scheduled for the Next Month

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

       Water Column Profiling of ESC CMP Vd;

       Routine Water Quality Monitoring of ESC CMP Vd;

       Water Quality Monitoring During Dredging of ESC CMP Vb; and

       Pit Specific Sediment Chemistry of ESC CMP Vd.

1.6.2                               No monitoring activities will be scheduled in the next monthly period of October 2016 for SB 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 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