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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

13TH MONTHLY PROGRESS REPORT FOR SEPTEMBER 2013

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 September 2013, the following works were being undertaken at the CMPs:

         Capping was being undertaken at CMP IVc;

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

         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 September 2013.

1.3                                      Details of Sampling and Laboratory Testing Activities

1.3.1                                No monitoring activities were undertaken for CMP IV and V in the monitoring month of September 2013.

1.3.2                                The following monitoring activities have been undertaken for SB CMPs in September 2013:

         Pit Specific Sediment Chemistry was conducted for SB CMP 1 on 26 September 2013

         Water Column Profiling was scheduled to be undertaken on 17 September 2013. However, there was no dumping activity at CMP 1 while the monitoring team was on-site. As such, in-situ measurements and water sampling were not undertaken for Water Column Profiling in September 2013; and

         Impact Water Quality Monitoring during Dredging Operations was undertaken for SB CMP 2 three times per week (i.e. 2, 4, 6, 9, 11, 13, 16, 18, 21, 25, 27, and 30 September 2013) in this reporting month in accordance with the EM&A Manual.

1.4                                      Details of Outstanding Sampling and/or Analysis

1.4.1                                No outstanding sampling remained for September 2013. Laboratory analyses of Pit Specific Sediment Chemistry of SB CMP 1 conducted in September 2013 are yet to be completed. A summary of field activities conducted are presented in Annex A.

1.5                                      Brief Discussion of the Monitoring Results for CMP V

1.5.1                                Pit Specific Sediment Chemistry Monitoring and Cumulative Impact Sediment Chemistry Monitoring for CMP Va are not conducted in September 2013 and the laboratory analysis of the monitoring activities undertaken in August 2013 is yet to be completed during the preparation of this monthly report. Hence, brief discussion of the monitoring results is not presented in this 13th Monthly Report. Detailed discussion will be presented in the corresponding Quarterly Report.

1.6                                      Brief Discussion of the Monitoring Results for SB CMPs

1.6.1                                Monitoring data collected for CMP 2 from 2 September to 30 September 2013 are presented in this monthly report. Detailed discussion will be presented in the corresponding Quarterly Report.

1.6.2                                Impact Water Quality Monitoring during Dredging Operations of CMP 2 2 September to 30 September 2013

1.6.3                                Impact Water Quality Monitoring during Dredging Operations of CMP 2 (i.e. from 2 September to 30 September 2013) was conducted three times per week for a total of nine (9) sampling days. 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 (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.

1.6.4                                Monitoring results from 2 September to 30 September are presented in Table B1 of Annex B. Sampling at THB2 was cancelled during mid-ebb tide on 4 September 2013 due to adverse weather. Sampling at THB2 was also cancelled during both mid-ebb and mid-flood tides on 21 September 2013 since severe Typhoon Usagi was approaching. Levels of DO, Turbidity and SS generally complied with the Action and Limit Levels (see Table B2 of Annex B 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 SB CMP 2 in September 2013

Date

Tide

Parameter

Station

Type

2 September 2013

Mid-Ebb

Bottom DO

WSR45C

Action

4 September 2013

Mid-Flood

Turbidity

WSR46

Limit

6 September 2013

Mid-Ebb

Turbidity

WSR46

Limit

 

Mid-Ebb

SS

WSR46

Action

 

Mid-Flood

Turbidity

DS1

Limit

 

Mid-Flood

SS

DS1

Limit

 

Mid-Flood

SS

WSR46

Action

18 September 2013

Mid-Ebb

Turbidity

WSR46

Action

 

Mid-Flood

SS

WSR45C

Action

21 September 2013

Mid-Flood

Turbidity

WSR46

Limit

 

Mid-Flood

SS

WSR46

Action

25 September 2013

Mid-Ebb

Turbidity

DS2

Limit

 

Mid-Ebb

SS

DS2

Limit

27 September 2013

Mid-Flood

SS

DS2

Action

1.6.5                                It should be noted that all exceedances except those on 6 September 2013 were recorded at stations which are located further away from the works area when compared to station DS1 at which the levels of SS, Turbidity and DO (Surface and Mid-depth) did not exceed the Action and Limit Levels during the same tidal period on the same day. As such, these recorded exceedances are not likely to be caused by the dredging works at CMP 2.

1.6.6                                On 6 September 2013, though exceedances of Action and Limit Levels were recorded at stations WSR46 and DS1, there did not appear to be any trend of increasing SS or Turbidity levels toward the dredging operations. Instead, high levels of Turbidity and SS and low levels of DO 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.

1.6.7                                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.

1.7                                      Activities Scheduled for the Next Month

1.7.1                                Pit Specific Sediment Chemistry, Routine Water Quality Monitoring and Water Column Profiling for CMP 1 as well as Impact Water Quality Monitoring during Dredging Operations for CMP 2 will be conducted in the next monthly period of October 2013.

1.7.2                                No monitoring activities will be conducted for CMP IV and CMP V in the next monthly period of October 2013.

1.7.3                                The sampling schedule is presented in Annex A.

1.8                                      Study Programme

1.8.1                                A summary of the Study programme is presented in Annex C.


 



([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.

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