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

47th MONTHLY PROGRESS REPORT FOR July 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 ESC CMPs and SB CMPs is shown in Figure 1.1. In July 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 47th Monthly Progress Report covers the EM&A activities for the reporting month of July 2016.

1.3                                      Details of Sampling and Laboratory Testing Activities

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

       Routine Water Quality Monitoring of ESC CMP Vd was undertaken on 4 July 2016;

       Water Column Profiling of ESC CMP Vd was undertaken on 5 July 2016;

       Pit Specific Sediment Chemistry of ESC CMP Vd was undertaken on 6 July 2016; and

       Demersal Trawling of ESC CMP Vd was undertaken on 27 and 28 July 2016.

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

1.4                                      Details of Outstanding Sampling and/or Analysis

1.4.1                                No outstanding sampling remained for July 2016.

1.4.2                                A summary of field activities conducted are presented in Annex A. The following analyses are in progress and will be presented in the corresponding quarterly report:

  Species identification of the biota samples collected from Demersal Trawling for ESC CMP Vd in July 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 47th Monthly Progress Report:

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

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

       Pit Specific Sediment Chemistry of ESC CMP Vd in July 2016.

1.5.2                                Routine Water Quality Monitoring of ESC CMP Vd July 2016

1.5.3                                Routine Water Quality Monitoring was undertaken on 4 July 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). The monitoring results are shown in Tables B2 and B3 of Annex B and Figures 1 - 10 of Annex C. A total of sixteen (16) monitoring stations were sampled in July 2016 as shown in Figure 1.2.

In-situ Measurements

1.5.4                                Graphical presentation of the monitoring results (Temperature, DO, pH, Salinity and Turbidity) is shown in Figures 1 - 6 of Annex C. Analyses of results for July 2016 indicated that the levels of pH and DO complied with the WQOs at all stations (Impact, Intermediate, Reference and Ma Wan stations) in July 2016 (Table B2 of Annex B; Figures 1, 2, 3 and 4 of Annex C). Levels of Salinity at Impact and Intermediate stations exceeded the WQOs (Table B2 of Annex B; Figure 5 of Annex C). The lower Salinities recorded at these stations is likely to be caused by the freshwater discharged from the Pearl River Delta during the summer months which tend to form a surface layer of lower salinity water at these stations with shallower depth when compared with the Reference stations.

1.5.5                                                                               The levels of DO and Turbidity complied with the Action and Limit Levels at all stations (Table B2 of Annex B; Figures 2, 3 and 6 of Annex C).

1.5.6                                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 July 2016.

Laboratory Measurements

1.5.7                                                                               Laboratory analysis of July 2016 results indicated that concentrations of Cadmium, Chromium, Silver and Mercury were below their limit of reporting at all stations. Arsenic, Lead, Nickel, Copper and Zinc were detected in July 2016 samples and the concentrations of these metals and metalloid were similar amongst stations, except higher concentration of Zinc was recorded at Impact stations (Table B3 of Annex B; Figure 7 of Annex C).

1.5.8                                                                               For nutrients, concentrations of Total Inorganic Nitrogen (TIN) at all stations in July 2016 exceeded the WQO (0.5 mg/L) (Table B3 of Annex B; Figure 8 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 B3 of Annex B; Figure 8 of Annex C). Levels of 5-day Biochemical Oxygen Demand (BOD5) appear to be higher at Reference station in July 2016 (Table B3 of Annex B; Figure 9 of Annex C).

1.5.9                                                                               Concentrations of SS were higher than the WQO (11.1 mg/L for wet season) at Impact and Reference stations. However, concentrations of SS complied with the Action and Limit Levels at all stations in July 2016 (Table B3 of Annex B; Figure 10 of Annex C).

1.5.10                            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 July 2016. Detailed statistical analysis will be presented in the Quarterly Report to investigate any spatial and temporal trends of potential concern.

1.5.11                            Water Column Profiling of ESC CMP Vd July 2016

1.5.12                            Water Column Profiling was undertaken on 5 July 2016. The monitoring results have been assessed for compliance with the WQOs (see Section 1.5.3 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).

In-situ Measurements

1.5.13                            Analyses of results for July 2016 indicated that levels of Salinity, DO and pH complied with the WQOs at both Downstream and Upstream stations (Table B4 of Annex B). In addition, DO and Turbidity at all stations complied with the Action and Limit Levels (Table B4 of Annex B).

Laboratory Measurements for Suspended Solids (SS)

1.5.14                            Analyses of results for July 2016 indicated that the SS levels were higher than the WQO at both Upstream and Downstream stations. Both Upstream and Downstream stations complied with the Action and Limit Levels (Table B4 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.

1.5.15                            Pit Specific Sediment Chemistry of ESC CMP Vd July 2016

1.5.16                            Monitoring locations for Pit Specific Sediment Chemistry for ESC CMP Vd are shown in Figure 1.3. A total of six (6) monitoring stations were sampled in July 2016.

1.5.17                            The concentrations of most inorganic contaminants were lower than the Lower Chemical Exceedance Level (LCEL) at all stations, except Arsenic (Figures 11 and 12 of Annex C). In July 2016, concentration of Arsenic at Active Pit station ESC-NPAB exceeded the LCEL (Figure 11 of Annex C).

1.5.18                            Whilst the average concentration of Arsenic in the Earths crust is generally ~2mg/kg, significantly higher Arsenic concentrations (median = 14 mg/kg) have been recorded in Hong Kongs onshore sediments ([9]). It is presumed that the natural concentrations of Arsenic are similar in onshore and offshore sediments ([10]), and relatively high Arsenic levels may thus occur throughout Hong Kong. Therefore, the LECL exceedances of Arsenic are unlikely to be caused by the disposal operations at ESC CMP Vd but rather as a result of naturally occurring deposits.

1.5.19                                                                           For organic contaminants, the concentrations of Total Organic Carbon (TOC) were similar amongst the stations in July 2016 (Figure 13 of Annex C). In July 2016, Tributyltin (TBT) concentrations were higher at Active Pit station ESC-NPAB (Figure 14 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 July 2016.

1.5.20                             

1.5.21                                                                           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 July 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 August 2016 for ESC CMPs:

       Water Column Profiling of ESC CMP Vd;

       Routine Water Quality Monitoring of ESC CMPs;

       Pit Specific Sediment Chemistry of ESC CMP Vd;

       Cumulative Impact Sediment Chemistry of ESC CMPs;

       Sediment Toxicity Test of ESC CMPs;

       Benthic Recolonisation Studies of ESC CMP IV; and

       Demersal Trawling of ESC CMPs.

1.6.2                               The following monitoring activities will be conducted in the next monthly period of August 2016 for SB CMPs:

       Water Quality Monitoring During Capping of SB CMPs; and

       Benthic Recolonisation Studies of 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

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

([9]) Sewell RJ (1999) Geochemical Atlas of Hong Kong.Geotechnical Engineering Office, Government of the Hong Kong Special Administrative Region

([10]) Whiteside PGD (2000) Natural geochemistry and contamination of marine sediments in Hong Kong.In: The Urban Geology of Hong Kong (ed Page A & Reels SJ). Geological Society of Hong Kong Bulletin No. 6, p109-121