Agreement No. CE 63/2016 (EP)
Environmental Monitoring and Audit
for Disposal Facility to the East of Sha Chau (2017-2020) - Investigation
MONTHLY EM&A REPORT FOR December 2018
1.1 Background
1.1.1 The Civil Engineering and Development Department (CEDD) is managing a number of marine disposal facilities in Hong Kong waters, including the Contaminated Mud Pits (CMPs) to the South of The Brothers (SB) and to the East of Sha Chau (ESC) for the disposal of contaminated sediment, and open-sea disposal grounds located to the South of Cheung Chau (SCC), East of Tung Lung Chau (ETLC) and East of Ninepins (ENP) for the disposal of uncontaminated sediment. Two 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 and 23 December 2011 for the Dredging, Management and Capping of Contaminated Sediment Disposal Facilities at ESC CMP V and SB CMPs, respectively.
1.1.2 Under the requirements of the two EPs for ESC CMP V and SB CMPs, EM&A programmes which encompass water and sediment chemistry, fisheries assessment, tissue and whole body analysis, sediment toxicity and benthic recolonisation studies as set out in the EM&A Manuals are required to be implemented. EM&A programmes have been continuously carried out during the operation of the CMPs at ESC and SB. A review of the collection and analysis of such environmental data from the monitoring programme demonstrated that there had not been any adverse environmental impacts resulting from disposal activities ([1]) ([2]). The current programme will assess the impacts resulting from dredging, disposal and capping operations of CMP V as well as capping operations of SB CMPs.
1.1.3 The present EM&A programme under Agreement No. CE 63/2016 (EP) covers the dredging, disposal and capping operations of the ESC CMP V as well as the capping operations of the SB CMPs (see Annex A for the EM&A programme). Detailed works schedule for ESC CMP V and SB CMPs is shown in Figure 1.1. In December 2018, the following work was being undertaken:
· Disposal of contaminated mud at ESC CMP Vd.
Figure 1.1 Works
Schedule for ESC
CMP V and SB CMPs
1.2 Reporting Period
1.2.1 This Monthly EM&A Report for December 2018 covers the EM&A activities for the reporting month of December 2018.
1.3 Details of Sampling and Laboratory Testing Activities
1.3.1 The following monitoring activities were undertaken for ESC CMP V in December 2018:
· Water Column Profiling of ESC CMP Vd;
· Pit Specific Sediment Chemistry of ESC CMP Vd; and
· Cumulative Impact Sediment Chemistry of ESC CMPs.
1.3.2 The following monitoring activity was undertaken for SB CMP in December 2018:
· Benthic Recolonisation Studies of SB CMPs.
1.4 Details of Outstanding Sampling and/or Analysis
1.4.1 No outstanding sampling remained for December 2018.
1.4.2 The following analyses are in progress and will be presented in the corresponding quarterly report:
· Species identification and analyses of sediment samples collected for Benthic Recolonisation Studies of SB CMPs in December 2018.
1.5 Brief Discussion of the Monitoring Results for ESC CMP V
1.5.1 Brief discussion of the monitoring results of the following activities for ESC CMP V is presented in this Monthly EM&A Report for December 2018:
· Water Column Profiling of ESC CMP Vd in December 2018;
· Pit Specific Sediment Chemistry of ESC CMP Vd in December 2018; and
· Cumulative Impact Sediment Chemistry of ESC CMPs in December 2018.
1.5.2 Water Column Profiling of ESC CMP Vd – December 2018
1.5.3 Water Column Profiling was undertaken at a total of two sampling stations (Upstream and Downstream stations) on 6 December 2018. 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 dry season period (November to March) of 2007 - 2016 from stations in the Northwestern Water Control Zone (WCZ), where the ESC CMPs are located ([3]). For Salinity, the averaged value obtained from the Reference (Upstream) station 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 December 2018 indicated that levels of Salinity, pH and DO complied with the WQOs at both Downstream and Upstream stations (Table B2 of Annex B). Levels of DO and Turbidity at all stations complied with the Action and Limit Levels (Tables B1 and B2 of Annex B).
Laboratory Measurements for Suspended Solids (SS)
1.5.5 Analyses of results for December 2018 indicated that the SS levels at both Downstream and Upstream stations complied with the WQO and the Action and Limit Levels at both Downstream and Upstream stations (Tables B1 and B2 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.
1.5.6 Pit Specific Sediment Chemistry of ESC CMP Vd – December 2018
1.5.7 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 on 3 December 2018.
1.5.8 The concentrations of all inorganic contaminants were lower than the Lower Chemical Exceedance Level (LCEL) at all stations in December 2018 (Figures 1 and 2 of Annex C).
1.5.9 For organic contaminants, the concentrations of Total Organic Carbon (TOC) varied between stations and were generally higher at Pit-Edge ESC-NEAA and Active-Pit ESC-NPAA stations, while generally lower at Near-Pit ESC-NNAA and Pit-Edge ESC-NEAB stations in December 2018 (Figure 3 of Annex C). Tributyltin (TBT), Low and High Molecular Weight Polycyclic Aromatic Hydrocarbons (PAHs), Total Polychlorinated Biphenyls (PCBs) Total dichloro-diphenyl-trichloroethane (DDT) and 4,4’-dichlorodiphenyldichloroethylene (DDE) concentrations were below the limit of reporting at all stations in December 2018.
1.5.10 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 December 2018. Statistical analysis will be undertaken and presented in the corresponding quarterly report to investigate whether there are any unacceptable impacts in the area caused by the contaminated mud disposal.
1.5.11 Cumulative Impact Sediment Chemistry of ESC CMP V – December 2018
1.5.12 Monitoring locations for Cumulative Impact Sediment Chemistry for ESC CMP V are shown in Figure 1.3. A total of nine (9) monitoring stations were sampled on 3 and 4 December 2018.
1.5.13 Analyses of results for the Cumulative Impact Sediment Chemistry Monitoring indicated that the concentrations of most inorganic contaminants were below the LCEL at all stations in December 2018, except concentrations of Arsenic were higher than the LCEL at Mid-field stations ESC-RMA and ESC-RMB (Figures 4 and 5 of Annex C). Whilst the average concentration of Arsenic in the Earth’s crust is generally ~2 mg/kg, significantly higher Arsenic concentrations (median = 14 mg/kg) have been recorded in Hong Kong’s onshore sediments ([4]). It is presumed that the natural concentrations of Arsenic are similar in onshore and offshore sediments ([5]), 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.
1.5.14 For organic contaminants, the concentrations of TOC varied between stations in December 2018, with the generally lower concentrations of TOC recorded at Far-field station ESC-RFB (Figure 6 of Annex C). The concentrations of TBT were generally higher at Near-field station ESC-RNB (Figure 7 of Annex C). Low and High Molecular Weight PAHs, PCBs, DDT and DDE concentrations were below the limit of reporting at all stations in December 2018.
1.5.15 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 December 2018. Statistical analysis will be undertaken and presented in the corresponding 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 January 2019 for ESC CMP V (see Annex A for the sampling schedule):
· Water Column Profiling of ESC CMP Vd;
· Routine Water Quality Monitoring of ESC CMPs;
· Pit Specific Sediment Chemistry of ESC CMP Vd; and
· Demersal Trawling for ESC CMPs.