Agreement No. CE 23/2012 (EP)
Environmental Monitoring and Audit
for Contaminated Mud Pits at the South of The Brothers and at East Sha Chau (2012-2017) - Investigation

17TH MONTHLY PROGRESS REPORT FOR January 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 East of Sha Chau (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 undertaken under Agreement No. CE 23/2012 (EP) covers the dredging, disposal and capping operations of the SB CMPs as well as CMPs at East of Sha Chau (ESC).  In January 2014, the following works were being undertaken at the CMPs:

P      Capping was being undertaken at CMP IVc and CMP Va;

P      Disposal of contaminated mud was taking place at SB CMP 1; and

P      Dredging operations were taking place at SB CMP 2.

1.2                                      Reporting Period

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

1.3                                      Details of Sampling and Laboratory Testing Activities

1.3.1                               No monitoring activities have been undertaken for CMP IV and V in the reporting month of January 2014.

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

P      Impact Water Quality Monitoring during Dredging Operations was undertaken for CMP 2 three times per week on 2, 4, 6, 8, 10, 13, 15, 17, 20, 22, 24, and 28 January 2014; 

P      Routine Water Quality Monitoring was undertaken for CMP 1 on 3, 7, 9, 11, 14, 16, 18, 21, 23, 25, 27, and 29 January 2014;

P      Demersal Trawling for CMP 1 was carried out on 7 and 8 January 2014;

P      Water Column Profiling for CMP 1 was undertaken on 9 January 2014; and

P      Pit Specific Sediment Chemistry was conducted for CMP 1 on 21 January 2014.

1.4                                      Details of Outstanding Sampling and/or Analysis

1.4.1                                No outstanding sampling remained for January 2014.  The following laboratory analyses were still in progress during the preparation of this monthly report and hence were not presented in this monthly report:

P      Laboratory analyses of sediment samples collected for Pit Specific Sediment Chemistry of CMP 1 in December 2013 and January 2014;

P      Laboratory analyses of sediment samples collected for Cumulative Impact Sediment Chemistry of CMP 1 in December 2013;

P      Laboratory analyses of water samples collected for Routine Water Quality Monitoring for CMP 1 from 18 to 29 January 2014; and

P      Laboratory analyses of Suspended Solids (SS) samples collected for Water Quality Monitoring during Dredging Operations of CMP 2 from 10 to 28 January 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 is presented in this 17th Monthly Report:

P      Impact Water Quality Monitoring during Dredging Operations of CMP 2 conducted from 11 December 2013 to 8 January 2014;

P      Water Column Profiling of CMP 1 conducted in January 2014;

P      Routine Water Quality Monitoring of CMP 1 undertaken from 3 to 16 January 2014; and

P      Pit Specific Sediment Chemistry of CMP 1 conducted in November 2013.

1.5.2                                Impact Water Quality Monitoring during Dredging Operations of CMP 2 V 11 December 2013 to 8 January 2014

1.5.3                                Monitoring data collected for CMP 2 from 11 December 2013 to 8 January 2014 are presented in this monthly report.  Detailed discussion will be presented in the corresponding Quarterly Report.

 

1.5.4                                Impact Water Quality Monitoring during Dredging Operations of CMP 2 was conducted three times per week from 11 December 2013 to 8 January 2014.  On each survey day, sampling was conducted during both mid-ebb and mid-flood tides at two Reference (Upstream) stations upstream and five Impact (Downstream) stations downstream 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 stations were monitored and locations of the sampling stations are shown in Figure 1.1.

1.5.5                                Monitoring results from 11 December 2013 to 8 January 2014 are presented in Table C1 of Annex C.  Daily dredging volume in December 2013 is reported in Annex D.  Levels of Dissolved Oxygen (DO), Turbidity and 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 occasions of exceedances shown in Table 1.1 below.

Table 1.1        Details of Exceedances Recorded at CMP 2 in December 2013/ January 2014

Date

Tide

Parameter

Station

Type

11 December 2013

Mid-Flood

Turbidity

DS1

Limit

 

 

SS

DS1

Limit

16 December 2013

Mid-Flood

SS

DS1

Action

20 December 2013

Mid-Flood

Turbidity

DS4

Action

 

 

SS

DS4

Action

23 December 2013

Mid-Flood

SS

DS2

Action

27 December 2013

Mid-Flood

SS

DS1

Action

4 January 2014

Mid-Flood

SS

DS1

Action

 

 

SS

DS2

Action

 

 

SS

WSR45C

Action

6 January 2014

Mid-Flood

Turbidity

DS2

Action

 

 

SS

DS2

Action

1.5.6                                Regarding the exceedances observed, most of them were recorded at one station only during the sampling event.  The exceedances on 4 January 2014 were recorded at three monitoring stations, however, these exceedances did not show any trend of increasing SS or Turbidity levels toward the dredging operations .  As such, it is considered that these exceedances were not indicating any unacceptable water quality impacts as a result of the dredging operations at the CMP 2. 

 

1.5.7                                In addition to the above, high levels of Turbidity and SS were occasionally recorded during baseline monitoring which are considered to be sporadic events and characteristic of water quality in this area of Hong Kong.  Therefore, the Action and Limit Level exceedances may be caused by natural background variation in water quality of the area.

1.5.8                                Overall, 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.

1.5.9                                Water Column Profiling of CMP 1 V January 2014

1.5.10                           Water Column Profiling was undertaken at a total of two sampling stations (Upstream and Downstream stations) on 9 January 2014.  The water quality monitoring results have been assessed for compliance with the Water Quality Objectives (WQOs) set by EPD.  This consists of a review of the EPD routine water quality monitoring data for the dry season period (November to March) of 2003-2012 from stations in the Northwestern Water Control Zone, where the CMPs are located.  For Salinity, the average value obtained from the Upstream station was used for the basis as the WQO.  The monitoring results were also compared with the Action and Limit Levels set in the EM&A Manual ([8]).  Graphical presentations of the monitoring results are provided in Annex B.

In-situ Measurements

1.5.11                           Analyses of results for 9 January 2014 indicated that levels of Salinity, pH and DO complied with the WQOs at both Upstream and Downstream stations (Figures 1-3 of Annex B).  DO and Turbidity complied with the Action and Limit Levels set in the EM&A Manual.

Laboratory Measurements for Suspended Solids (SS)

1.5.12                           Analyses of data obtained on 9 January 2014 indicated that the SS levels at Downstream and Upstream stations complied with the WQO (Figure 4 of Annex B).  In addition, SS levels at all the stations complied with the Action and Limit Levels set in the EM&A Manual.

1.5.13                           Overall, in-situ measurement and laboratory analyses results indicated that the mud disposal operation at CMP 1 did not appear to cause any deterioration in water quality during this reporting period.

 

1.5.14                            Routine Water Quality Monitoring of SB CMP 1 V January 2014

1.5.15                           The monitoring results for the Routine Water Quality Monitoring conducted on 3, 7, 9, 11, 14 and 16 January 2014 in the dry season have been assessed for compliance with the WQOs set by EPD.  This consists of a review of the EPD routine water quality monitoring data for the dry season period (November to March) of 2003-2012 from stations in the Northwestern Water Control Zone, where the CMPs are located.  For Salinity, the averaged value obtained from the Reference stations was used for the basis as the WQO. 

1.5.16                           Daily in-situ monitoring and daily laboratory results are shown in Tables C3 and C4 of Annex C.  Monthly averaged in-situ measurement and laboratory analyses results for January 2014 will be presented with graphical presentation in the next monthly report when all the laboratory analyses are completed.  Locations of monitoring stations were presented in Figure 1.2 and 1.3.

In-situ Measurements

1.5.17                           Analyses of results indicated that for all the stations (Impact, Intermediate, Reference and Water Sensitive Receiver stations), daily levels of pH, DO and Salinity complied with the WQOs (Table C3 of Annex C).   

1.5.18                           Levels of Temperature, Salinity and pH showed similar magnitude from 3 to 16 January 2014 (Figure 5, 6 and 10 of Annex B) at all the stations.  Levels of DO were detected to fluctuate over time from 3 to 16 January 2014 and also showed relative variations amongst the stations (Figure 9 of Annex B).

1.5.19                           Daily levels of Turbidity from 3 to 16 January 2014 all complied with the Action and Limit Levels set in the EM&A Manual (Tables C3 of Annex C), except Turbidity levels at Intermediate Station and Ma Wan Station on 3 January 2014.  Fluctuation of Turbidity levels over time from 3 to 16 January 2014 was also recorded (Figure 7 of Annex B).  Levels of Turbidity also showed relative variations amongst the stations.

Laboratory Measurements

1.5.20                            Laboratory analyses results of metals and nutrients are presented in Table C4 of Annex C.  Graphical presentations of monitoring results on individual monitoring days are presented in Figure 11-23 of Annex B. 

1.5.21                            Analyses of 3 to 16 January 2014 results indicated that concentrations of Silver, Cadmium and Mercury were below their limit of reporting at all the stations (Figure 11, 13 and 17 of Annex B).  Recorded concentrations of Arsenic, Chromium, Copper, Lead, Nickel and Zinc indicated variations over time at all the stations from 3 to 16 January 2014 without any trend of increasing contaminant concentrations towards the pit (Figure 12, 14, 15, 16, 18 and 19 of Annex B). 

 

1.5.22                            Daily recorded levels of TIN, BOD5 and NH3-N were observed to fluctuate over time through 3 to 16 January 2014 (Figure 20-22 of Annex B).  Compliance with TIN WQO (0.50 mg/L) was recorded at all the stations in the monitoring period except the measurement at Water Sensitive Receiver station THB1 on 9 January 2014.  The only exceedance of TIN WQO at Water Sensitive Receiver station THB1 on one day did not provide any evidence of unacceptable water quality impacts due to the mud disposal activities.

1.5.23                            Daily levels of SS from 3 to 16 January 2014 all complied with the Action and Limit Levels set in the EM&A Manual (Tables C4 of Annex C).  Exceedances of SS WQO (14.4 mg/L for dry season) were recorded (Figure 23 of Annex B) from 3 to 16 January 2014.  The exceedances of WQO were recorded at Reference stations, Impact stations and other Water Sensitive Receiver stations on the same monitoring day (3 January 2014).  The reference stations are located upstream from the mud pits and considered unlikely to be affected by mud disposal works.  In addition, the SS levels at Impact stations were recorded lower than those at Reference or Intermediate stations.  Given the information above, it is considered that the exceedances of SS WQO are unlikely to be caused by mud disposal operations.  Instead, high levels of SS were occasionally recorded during baseline monitoring which are considered to be sporadic events and characteristic of water quality in this area of Hong Kong. 

1.5.24                            The exceedances of SS WQO on 7, 11, 14, and 16 January 2014 were also recorded at stations which are located further away from the works area when compared to Impact stations at which the levels of SS did not exceed WQO on the same day.  Hence, these exceedances of WQO are not considered to be caused by mud disposal works. 

1.5.25                            Overall, in-situ measurement and laboratory analyses results indicated that the disposal operation at CMP 1 did not appear to cause any unacceptable deterioration in water quality during monitoring period of 3 to 16 January 2014.

1.5.26                            Pit Specific Sediment Chemistry of CMP 1 V November 2013

1.5.27                           Monitoring locations for Pit Specific Sediment Chemistry for CMP 1 are shown in Figure 1.4.  A total of six monitoring stations were sampled in November 2013. 

1.5.28                           The concentrations of all the metals except Arsenic, Copper, Lead, Silver and Zinc complied with the Lower Chemical Exceedance Level (LCEL) at most stations in November 2013 (Figures 24 and 25 of Annex B).  Concentrations of Arsenic exceeded the LCEL at all stations except Active Pit station SB-NPAB.  Levels of Copper, Lead, Silver and Zinc exceeded the LCEL at Active Pit station SB-NPAB only.

 

1.5.29                            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 CMP 1 but rather as a result of naturally occurring deposits. 

1.5.1                                The concentration of Total Organic Carbon (TOC) concentration showed variations amongst the stations in November 2013 (Figure 26 of Annex B).  Tributyltin (TBTs) concentrations were found to be higher at Active Pit station SB-NPAB (Figure 27 of Annex B) in November 2013. 

1.5.2                               Low Molecular Weight Polycyclic Aromatic Hydrocarbons (MW PAHs) concentrations were recorded below the limit of reporting at all stations except Active Pit station SB-NPAB in November 2013 (Figure 28 of Annex B). The concentrations of Low MW PAHs at Active Pit station SB-NPAB are recorded below LCEL.  High MW PAHs concentrations were recorded below the limit of reporting at all stations except Active Pit stations SB-NPAA and SB-NPAB in November 2013 (Figure 28 of Annex B).  High MW PAHs concentrations at Active Pit station SB-NPAB exceeded LCEL in November 2013.

1.5.3                               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 the stations except Active Pit station SB-NPAB in October 2013.  Total PCBs concentrations at Active Pit station SB-NPAB exceeded LCEL in November 2013.

1.5.4                               Active Pit stations SB-NPAA and SB-NPAB are located within CMP 1 which was receiving contaminated mud during the reporting period.  Therefore, the higher concentrations of contaminants (including metals and organic contaminants) recorded at the Active Pit stations only are not considered as indicating any dispersal of contaminated mud from CMP 1.  Nevertheless, detailed analyses will be presented in the Quarterly Report to reveal any trend of increasing sediment contaminant concentrations towards CMP 1.

1.5.5                               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 during this monthly 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 February 2014 for SB CMPs:

P      Impact Water Quality Monitoring during Dredging Operations of CMP 2; 

P      Pit Specific Sediment Chemistry of CMP 1;

P      Cumulative Impact Sediment Chemistry of CMP 1;

P      Sediment Toxicity Test of CMP 1;

P      Tissue/ Whole Body Sampling of CMP 1;

P      Demersal Trawling of CMP 1;

P      Routine Water Quality Monitoring of CMP 1; and

P      Water Column Profiling of CMP 1.

1.6.2                               Water Quality Monitoring during Capping of CMP V will be conducted in the next monthly period of February 2014.

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 V 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.

([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) V 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) V 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) V Investigation. Agreement No. CE 23/2012(EP). Submitted to EPD in October 2012.

([8])    ERM (2009). Draft Second Review of the EM&A Manual. Prepared for CEDD for EM&A for Contaminated Mud
       Pit at Sha Chau (2009-2013) V Investigation Agreement No. CE 4/2009 (EP).

([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