Description: Pages from 0103262 Monthly Progress Jan 13_v0_Page_1

Description: Pages from 0103262 Monthly Progress Jan 13_v0_Page_2

Description: Pages from 0103262 Monthly Progress Jan 13_v0_Page_3

 

 

 

 

Agreement No. CE 4/2009 (EP)
Environmental Monitoring and Audit
for Contaminated Mud Pit at Sha Chau (2009-2013) - Investigation

 

43RD MONTHLY PROGRESS REPORTFOR CONTAMINATED MUD PITS AT SHA CHAU January 2013

 

1.1                                      Background

1.1.1                               Since 1992, the East of Sha Chau (ESC) area has been the site of a series of dredged contaminated mud pits (CMPs) designed to provide confined marine disposal capacity for contaminated mud arising from the HKSARs dredging and reclamation projects.  In January 2013, the following works were being undertaken at the CMPs:

P         Capping was being undertaken at CMP IVc;

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

P         Dredging of CMP Vd was in progress.

1.1.2                               The Environmental Monitoring and Audit (EM&A) programme for the CMPs at the ESC area presently covers the above operations.

1.2                                      Reporting Period

1.2.1                                This Monthly Progress Report covers the monitoring period of January 2013.

1.3                                      Details of Sampling and Laboratory Testing Activities

1.3.1                               The following monitoring activities have been undertaken for CMP V in January 2013:

P         Water Column Profiling was conducted for CMP Va on 4 January 2013;

P         Pit Specific Sediment Chemistry was conducted for CMP Va on 11 January 2013;

P         Demersal Trawling was conducted for CMP Va on 17 and 18 January 2013;

P         Routine Water Quality Monitoring was conducted for CMP Va on 18 January 2013; and

P         Impact Water Quality Monitoring during Dredging Operations was conducted for CMP Vd on 23 January 2013.

1.3.2                               A summary of field activities are presented in Annex A.

1.4                                      Details of Outstanding Sampling and / or Analysis

1.4.1                               No outstanding sampling remained and laboratory analysis of Pit Specific Sediment Chemistry conducted in January 2013 was yet to be completed during preparation of this monthly report. 

1.5                                      Brief Discussion of the Monitoring Results for CMP V

1.5.1                               Table 1.1 summarises the monitoring results that are presented in the current monthly report.  Brief discussion of the monitoring results is presented in this section.  Detailed discussion will be presented in the corresponding Quarterly Report.

Table 1.1        Monitoring activities in December 2012/January 2013

Monitoring activities

Date of Monitoring

Monitoring results presented in this report?

Cumulative Impact Sediment Chemistry Monitoring for CMP Va

3 Dec 2012

Yes

 

 

 

Pit Specific Sediment Chemistry Monitoring for CMP Va

 

7 Dec 2012

 

11 Jan 2013

Yes

 

No.  Laboratory analysis yet to be completed during preparation of this monthly report.

 

Water Column Profiling for CMP Va

 

4 Jan 2013

Yes

Demersal Trawling for CMP Va

17&18 Jan 2013

No.  Laboratory analysis yet to be completed during preparation of this monthly report.

 

 

 

Routine Water Quality Monitoring for CMP Va

18 Jan 2013

Yes

 

 

 

Impact Water Quality Monitoring during Dredging Operations of CMP Vd

23 Jan 2013

Yes

1.5.2                                Pit Specific Sediment Chemistry of CMP Va V December 2012

1.5.3                               Monitoring locations for Pit Specific Sediment Chemistry for CMP Va are shown in Figure 1.1.  A total of six monitoring stations were sampled in December 2012.  Concentrations of Arsenic exceeded the Lower Chemical Exceedance Level (LCEL) at all stations except at Active Pit station NPDA while concentrations of Silver exceeded the LCEL at Active Pit station NPDA (Figures 1-2 of Annex B).  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 ([1]).  It is presumed that the natural concentrations of Arsenic are similar in onshore and offshore sediments ([2]), and relatively high Arsenic levels may thus occur throughout Hong Kong.   Therefore, the slight exceedances of the LCEL for Arsenic are unlikely to be caused by the disposal operations at CMP Va but rather as a result of naturally occurring deposits.  In addition, the Active Pit stations are located within CMP Va which was receiving contaminated mud during the reporting period.  As such, the exceedances of LCEL for Silver which were recorded at one Active Pit station only is not considered as indicating any dispersal of contaminated mud from CMP Va.

1.5.4                               For organic contaminants, Total Organic Carbon (TOC) concentration was similar amongst all stations (Figure 3 of Annex B).  Tributyltin (TBT) concentration was higher at Active Pit Station NPDA and Pit Edge Station NEDB when compared to other stations (Figure 4 of Annex B).  High MW PAHs concentrations were below the limit of reporting at all stations except at Active Pit stations NPDA and NPDB and Pit-Edge station NEDB (Figure 5 of Annex B).  Low Molecular Weigh Polycyclic Aromatics Hydrocarbons (Low MW PAHs), Total Polychlorinated Biphenyls (PCBs), Total Dichloro-diphenyl-trichloroethane (DDT) and 4,4-Dichloro-diphenyl-dichloroethylene (4,4-DDE) were below the limit of reporting at all stations.

1.5.5                               As described in Section 1.5.3, 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 Va.  Nevertheless, detailed analysis will be presented in the Quarterly Report to reveal any trend of increasing sediment contaminant concentrations towards CMP Va.

1.5.6                               Overall, there is no evidence indicating any unacceptable environmental impacts to sediment quality as a result of the contaminated mud disposal operations at CMP Va during this monthly period.

 

1.5.7                                Cumulative Impact Sediment Chemistry for CMP Va V December 2012

1.5.8                               Monitoring locations for Cumulative Impact Sediment Chemistry for CMP Va are shown in Figure 1.2.  A total of nine monitoring stations were being sampled.

1.5.9                                Analyses of results for the Cumulative Impact Sediment Chemistry Monitoring indicate that the concentrations of all metals, except Arsenic, were below the LCEL in December 2012 (Figures 6 and 7 of Annex B).  Concentrations of Arsenic in sediments from all stations, except for Ma Wan station, Near Field stations RNA and RNB, exceeded the LCEL.  As discussed in Section 1.5.3 above, relatively high natural levels of Arsenic are present in Hong Kongs marine sediments and hence the slight exceedances of the LCEL for the Arsenic do not necessarily indicate any adverse impacts to sediment quality caused by disposal operation at CMP Va.

1.5.10                            The concentration of TOC was similar amongst stations (Figure 8 of Annex B).  TBTs were recorded in sediment samples from Near Field (RNA and RNB), Mid Field (RMA and RMB), Far-field (RFA), Capped Pit (RCA) and Ma Wan stations (Figure 9 of Annex B).  Concentrations of Total DDT, 4,4-DDE, Total PCBs, Low and High M.W. PAHs were below the limit of detection at all stations. 

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 CMP Va during this monthly period.

1.5.12                            Impact Water Quality Monitoring during Dredging Operations of CMP Vd V January 2013

1.5.13                            Impact Water Quality Monitoring during Dredging Operations of CMP Vd was conducted on 23 January 2013.  On the 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 Vd (Figure 1.3).  Monitoring was also conducted at Ma Wan station.  At each station, in-situ measurements of water quality parameters as well as water samples were taken from three depths in the water column (ie surface: 1 m below sea surface, mid-depth and bottom: 1 m above the seabed).  Where water depth is less than 6 m, the mid-depth station was omitted.  If water depth is less than 3 m, only the mid-depth station was monitored.

1.5.14                           Monitoring results are presented in Table C1 of Annex C.  Levels of Dissolved Oxygen (DO), Turbidity and Suspended Solids (SS) complied with the Action and Limit Levels set in the Baseline Monitoring Report ([3]).

1.5.15                           Overall, there appears to be no unacceptable water quality impacts causing by the dredging operations at CMP Vd and no additional measures are thus considered required except for those stated in the Environmental Permit (EP-312/2008).

1.5.16                            Water Column Profiling for CMP Va V January 2013

In-situ Measurements

1.5.17                           Water Column Profiling was undertaken at a total of two sampling stations (Upstream and Downstream stations) in January 2013.  The water quality monitoring results for January 2013 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 1999-2010 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.  Graphical presentation of the monitoring results is provided in Annex B.

1.5.18                           Analyses of results for January 2013 indicated that levels of Salinity, pH and DO complied with the WQOs at both Upstream and Downstream stations (Figures 10 - 12 of Annex B).  DO and Turbidity complied with the Action and Limit Levels set in the EM&A Manual ([4]).

Laboratory Measurements for Suspended Solids (SS)

1.5.19                           Analyses of data obtained in January 2013 indicated that the SS levels at both Upstream and Downstream stations complied with the WQO (Figure 13 of Annex B).  In addition, SS levels at all stations complied with the Action and Limit Levels set in the EM&A Manual.

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

1.5.21                            Routine Water Quality Monitoring for CMP Va V January 2013

1.5.22                           The results for the Routine Water Quality Monitoring conducted during January 2013 in the dry season have been assessed for compliance with the WQOs set by EPD as presented in Section 1.5.18 above (please see Figure 1.4 for the monitoring locations).  In-situ monitoring and laboratory results are shown in Tables 1.2 and 1.3, respectively, with graphical presentation provided in Annex B.  Monitoring was undertaken at a total of ten stations in the reporting month.

In-situ Measurements

1.5.23                           Analysis of results for January 2013 indicated that for all stations (Impact, Intermediate and Reference), levels of pH, DO and salinity complied with the WQOs (Figures 14-17 of Annex B).  Levels of DO and Turbidity within the reporting month complied with the Action and Limit Levels set in the EM&A Manual ([5]) (Figures 15 and 18 of Annex B).  All in-situ water quality measurements showed relatively minor variations amongst Impact, Intermediate and Reference stations (Figures 14-18 of Annex B).

Laboratory Measurements

1.5.24                            Analyses of January 2013 results indicate that concentrations of Cadmium, Mercury and Silver were below their limit of reporting at all stations.  Arsenic, Copper, Lead, Nickel and Zinc were detected in samples from all stations (Figures 19 and 20 of Annex B).  Concentrations of Arsenic, Chromium, Lead and Nickel appeared to be similar amongst all stations while concentration of Zinc was the highest at Reference stations.  Levels of 5-day Biochemical Oxygen Demand (BOD5), Total Inorganic Nitrogen (TIN) and NH3-N were similar amongst all stations (Figures 21 and 22 of Annex C).  Concentrations of SS complied with the WQO (15.34 mg/L for dry season) and Action and Limit Levels at all stations within the reporting month (Figure 23 of Annex C).

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

Table 1.2        In-situ Monitoring Results for Routine Water Quality Monitoring during January 2013

Stations

Temp

Salinity

Turbidity

pH

Dissolved Oxygen

 

((C)

 

(NTU)

 

(%)

(mg L-1)

RFF (Reference)

17.36

32.12

3.12

7.79

100.47

7.94

IPF (Impact)

17.46

32.19

4.89

7.76

97.85

7.72

INF (Intermediate)

17.46

32.16

3.09

7.73

98.62

7.78

Ma Wan Station

17.60

32.87

2.54

7.73

93.10

7.29

WQO

N/A

28.91-35.33#

N/A

6.5-8.5

N/A

>4

Note:   #Not exceeding 10% of natural ambient level which is the result obtained from the Reference Station.

Table 1.3        Laboratory Results for Routine Water Quality Monitoring during January 2013

Stations

As

(µg/L)

Ag

(µg/L)

Cd

(µg/L)

Cr

(µg/L)

Cu

(µg/L)

Hg

(µg/L)

Pb

(µg/L)

Ni

(µg/L)

Zn

(µg/L)

NH3-N

(mg/L)

TIN

(mg/L)

BOD5

(mg/L)

SS

(mg/L)

RFF

1.04

<LOR

<LOR

1.60

7.83

<LOR

4.42

3.83

10.79

0.17

0.38

2.41

4.88

IPF

1.13

<LOR

<LOR

1.00

11.08

<LOR

2.29

2.75

8.54

0.14

0.34

1.72

8.46

INF

<LOR

<LOR

<LOR

2.19

7.29

<LOR

2.63

4.58

8.88

0.12

0.34

2.15

5.08

Ma Wan Station

<LOR

<LOR

<LOR

1.44

7.56

<LOR

3.88

2.00

10.50

0.11

0.25

0.65

4.13

WQO of SS

15.34

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 2013 for CMP V:

P       Pit Specific Sediment Chemistry for CMP Va;

P       Cumulative Impact Sediment Chemistry for CMP Va;

P       Sediment Toxicity for CMP Va;

P       Tissue/ Whole Body Sampling for CMP Va;

P       Demersal Trawling for CMP Va;

P       Routine Water Quality Monitoring for CMP Va;

P       Water Column Profiling for CMP Va; and

P       Impact Water Quality Monitoring during Dredging Operations for CMP Vd.

1.6.2                               Water Quality Monitoring during Capping will be conducted for CMP IVc in the next monthly period of February 2013.

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

([2])     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

([3])        ERM (2009)  Baseline Monitoring Report.  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 September 2009.

 

([4])    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).

 

([5])   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).