Emissions Control Project at
Sediment Sampling and
Testing Programme
1. Background Information
The operations of the Emissions Control Project at Castle Peak Power
Station “B” Units will involve the use of reagents and the production of
process by-products. The reagents
and by-product are expected to be transported via marine transport and new
berthing facilities are expected to be required for the loading and unloading
of these materials.
The existing Heavy Load Berth along the north-western waterfront of the
Castle Peak Power Station will be extended to form a multi-purpose wharf and to
provide the additional berthing facilities required. Dredging will be required for the
development of the new berthing facilities. The exact extent and boundary of the
dredging works is still being streamlined but the total area required to be
dredged is currently estimated to be approximately 30,000 m2. The dredged level is expected to be up
to a depth of –8.2 mPD with the total dredged volume
is estimated at 80,700 m3.
The preliminary proposed dredge area is presented in Sketch No. 24443/HLB/SK/007 in Annex D1a.
2. Sampling Arrangement
Vibrocore of sediment materials for testing of potential contaminants
in the sediment is proposed within the proposed dredging area for the new
berthing facilities ([1]).
Based on the existing sediment quality data published by EPD for the
monitoring stations at Pillar Point and Urmston Road (NS3 and NS4), the
sediment quality in the area is considered to be not contaminated.
Based on the total area expected to be dredged, vibrocore
samples of sediments are proposed to be taken at three locations evenly
distributed within the area to be dredged.
The proposed sampling locations are presented in Sketch No. 24443/HLB/SK/007 in Annex D1a.
3. Sampling
CAPCO’s site investigation contractor will carry out the
sampling and provide all necessary equipment. Equipment will be located onto barges and
the barges will be towed to the Site prior to sampling.
The contractor will ensure that adequate sediment samples are collected
for chemical testing as well as the next Tier of biological testing, based on
the laboratory requirement. If one vibrocore recovery is deemed not adequate for conducting
all proposed laboratory testing, the contractor’s supervisor will be
responsible to carry out additional sampling immediately to ensure adequate
sediment samples are recovered. Vibrocore sampling will be conducted to the end of the
proposed dredging level or at refusal (ie end of
sediment layer). The vibrocores will be cut on-site at proposed sampling depths
at the existing seabed surface, -0.9m, -1.9m, -2.9m and every 3m
thereafter. They will then be
inventoried and logged on chain-of-custody forms as described above.
All sediment and water samples will be stored at 4°C during transportation and at the
laboratory prior to testing.
The proposed sample container for each test is described in Annex
D1b.
Sediment samples will be extracted in the laboratory and placed in the
appropriate containers directly after the sampling. All samples will be double-bagged and
labelled internally and externally with indelible ink. CAPCO contractor’s Standard Operating Procedure (SOP) for Extrusion &
Homogenization of Sediment Samples is attached in Annex D1c.
Each sub-sample for chemical testing will be analysed for parameters as
presented in Section 5 below.
Samples will be extracted and analysed within 14 days. The laboratory will ensure that the
chemical screening results are ready as soon as possible after the sampling
finished so that a Tier III biological testing programme (where required) can
be developed and commenced within 8 weeks from the date of sampling.
The
sub-samples for biological testing will also be stored in the same manner as
described above (including for ancillary parameters). The composite samples for biological
testing, where required, will comprise of composite samples prepared from up-to
5 sub-samples of the same category (ie sediment
classified under ETWBTCW 34/2002 as (category M or H), which are
continuous in vertical or horizontal profile. The composite samples for biological
testing will also be tested for ancillary parameters, including moisture
content, grain size distribution, pH, TOC, ammonia and salinity of pore water.
4. Reference Sample
If Tier III biological testing programme is anticipated, samples for
reference sediment will be taken, prior to the initiation of the biological
testing programme. The site for
collecting reference sediment is in Port Shelter at PS6 (E850234, N820057).
All samples will be tested for all the contaminants stated in Table 1 - Analytical Methodology in Appendix B of ETWBTCW 34/2002 and other proposed parameters including: metals (Cd, Cr, Cu, Hg, Ni, Pb, Ag, Zn),
metalloid (As), organic-PAHs (low molecular weight PAHs (including Naphthalene, Acenaphtylene,
Acenaphtene, Fluorene, Phenanthrene, Anthracene) and
high molecular weight PAHs (including Benzo(a)anthracene, Benzo(a)pyrene, Chrysene, Dibenz(ah)anthracene, Fluoranthene, Pyrene, Benzo(b)fluoranthene, Benzo(k)fluoranthene, Indeno(1,2,3-cd)pyrene, Benzo(ghi)perylene)),
PCBs (including 2,4' dichlorobiphenyl (PCB 8), 2,2',5
trichlorobiphenyl (PCB 18), 2,4,4' trichlorobiphenyl (PCB 28), 2,2',3,5' tetrachlorobiphenyl
(PCB 44), 2,2',5,5' tetrachlorobiphenyl (PCB 52),
2,3',4,4' tetrachlorobiphenyl (PCB 66), 3,3',4,4' tetrachlorobiphenyl (PCB 77), 2,2',4,5,5' pentachlorobiphenyl (PCB 101), 2,3,3',4,4' pentachlorobiphenyl (PCB 105), 2,3',4,4',5 pentachlorobiphenyl (PCB 118), 3,3',4,4,5 pentachlorobiphenyl (PCB 126), 2,2',3,3',4,4' hexachlorobiphenyl (PCB 128), 2,2',3,4,4',5' hexachlorobiphenyl (PCB 138), 2,2',4,4',5,5' hexachlorobiphenyl (PCB 153), 3,3',4,4',5,5' hexachlorobiphenyl (PCB 169), 2,2',3,3',4,4',5 heptachlorobiphenyl (PCB 170), 2,2',3,4,4',5,5' heptachlorobiphenyl (PCB 180), 2,2',3,4',5,5',6 heptachlorobiphenyl (PCB 187) and Total PCBs (as sum of the
18 congenors)), chlorinated pesticides (including,
Alpha-BHC, Beta BHC, Gamma BHC Delta-BHC, Heptachlor, Aldrin,
Heptachlor epoxide, Endosulfan
1, p, p'-DDT, p, p'-DDD, p, p'-DDE and Endosulfan
sulphate), TBT in interstitial water and other parameters relating to water
quality impact assessment (particle size, redox
potential, TOC, TKN, nitrate, nitrite, ammonia nitrogen, ortho-phosphate,
total phosphorus).
Elutriate samples will be analysed for metals (Cd,
Cr, Cu, Hg, Ni, Pb, Ag, Zn), metalloid (As), organic-PAHs (low molecular weight and high molecular weight PAHs), PCBs, chlorinated pesticides, TBT, and other
parameters relating to water quality impact assessment (ammonia, TKN, nitrate,
nitrite, ammonia nitrogen, ortho-phosphate, total
phosphorus, biological and chemical oxygen demand).
Water samples will be taken at 3 depths, ie 1m
below surface, mid-depth and 1m above the seabed level. If the seabed level is less than 6m but
more than 3m, samples will be taken at 1m below surface and mid-depth. If the seabed level is less than 3m,
samples will be taken at 1m below surface.
Water samples will be tested for metals, ammonia, TKN, nitrate, nitrite,
ammoniacal nitrogen, ammonia nitrogen,
orthophosphate, total phosphorus,
PAHs, PCBs, chlorinated
pesticides and TBT.
List of the instrumentation, analytical
methods and reporting limit of individual parameters for sediment, elutriate, interstitial water and water samples are
summarized in Annex D1d.
6. Quality Assurance/Quality Control
The laboratory should ensure that all equipment and instruments to be
used for analysis meet the requirements and specifications of the reference
method procedures. The laboratory
will set upper and lower control limits based on statistical analysis of
historical performance data to monitor the acceptability of the QA/QC sample
data. All instruments will be
calibrated prior to analysis to monitor sensitivity and precision.
The following QA/QC samples will be analysed.
·
Laboratory blanks - an analyte
free matrix to which all reagents are added in the same volumes or proportions
as used in the standard sample preparation to monitor contamination introduced
in the laboratory (inorganics and organics).
·
Field blanks – a control standard solution to be used for monitoring of potential
contamination of samples from the environmental suring
the on-site sample handling. A
field blank shall be collected for each set of samples for analysis of organic
contents (PAHs).
·
Batch duplicates - an intra laboratory split sample
randomly selected from the sample batch to monitor method precision (intra
batch) in a given sample matrix (inorganics
only). It is proposed that
duplicate samples of 5% from each batch will be analysed.
·
Reference Materials - analysis of a material with a known
concentration of contamination to determine the accuracy of results in a given
matrix (inorganics only) (eg
CASS 3).
·
Single Control Samples - a known, interference-free matrix
spiked with target analytes used to monitor
laboratory preparation techniques (organics only).
·
Duplicate Control Samples - multiple single control samples
designed to monitor preparation technique reproducibility (organics only).
·
Matrix Spike - An intra laboratory split sample spiked with the
target analytes prior to sample preparation and
analysis to determine method bias in a given sample matrix (organics only).
A laboratory blank, a batch duplicate (5%
of each batch) and a suitable reference material will be analysed with batch of
samples. For organics, a method
spike will also be analysed with each batch of samples. Each batch will contain a maximum of 20
samples. Results of instrument
calibration checks and QA/QC results will be included in each laboratory
report. Data Quality Objectives (DQOs) have been developed to address precision, accuracy
and analyte recovery, as described below.
Duplicates (1 in every 10 samples) will be
used to monitor the precision of the analysis. Results will be flagged for reference
when:
·
For
all analytes, except metals, with concentration
>4x Method Detection Limit (MDL), the duplicate results have more than a 20%
Relative Percentage Deviation (RPD);
·
For
metals with a concentration >4x MDL, the duplicate results have more than a
25% RPD; and
·
For
all analytes with concentration <4x MDL, the
duplicate results will be reported as analysed and no bounds will be quoted.
Standard and certified reference material (CRM) are used to monitor accuracy and precision
within and between batches: Results
should be flagged for reference if:
·
The
variation of the standard from its true value is more than 15% (for mercury:
20%).
Post digest spikes are used to determine
the recovery of determinants in complex sample matrices. Results should be rejected if:
Spike recoveries are more than 25% from the theoretical recovery for
waters, sediment and marine biota.
An exceptional case would be if the sample concentration is greater than
four times the spike value, the spike may be disregarded.
7. Sediment Classification
The tested sediment samples will be classified according to their level
of contamination of metals (eight priority metals, including Cd, Cr, Cu, Hg, Ni, Pb, Ag and
Zn), metalloid (arsenic), organic–PAHs (low molecular
and high molecular weight PAHs), organic-non-PAHs (total polychlorinated biphenyls) and organometallics (tributyltin in
interstitial water) as stipulated in ETWBTCW
34/2002. The Chemical Exceedance Levels (CEL) specified in Appendix A of ETWBTCW 34/2002 serve
as criteria for determining the testing and disposal requirements of marine
dredged sediments. These include:
Category L: Sediment
with all contaminant levels not exceeding the Lower Chemical Exceedance Level (LCEL). The material must be dredged,
transported and disposed of in a manner, which minimizes the loss of
contaminants either into solution or by resuspension.
Category M: Sediment with
any one or more contaminant levels exceeding the Lower Chemical Exceedance Level (LCEL) and none exceeding the Upper
Chemical Exceedance Level (UCEL). The material must be dredged and
transported with care, and must be effectively isolated from the environment
upon final disposal unless appropriate biological tests demonstrate that the
material will not adversely affect the marine environment.
Category H: Sediment
with any one or more contaminant levels exceeding the Upper Chemical Exceedance Level (UCEL). The material must be dredged and
transported with great care, and must be effectively isolated from the
environment upon final disposal.
8. Necessity to Proceed to Tier III Biological Screening
There is no need to proceed to Tier III for Category L sediment. However, the Tier III biological testing
must be implemented for further analysis of Category M and certain Category H
sediment. For the latter, Tier III
screening is only required if one or more contaminant levels exceed 10 times
the LCEL.
In order to determine whether sediment with contaminant concentrations
exceeding LCEL and over 10 times LCEL present a toxicological risk to biota
inhabiting areas adjacent to the contaminated mud disposal site during their
disposal, ecotoxicological evaluations (bioassays)
will be performed on these sediment samples. The ecotoxicological
testing programme featured a suite of tests that include three phylogenetically distinct species which interact with
bedded sediments in different ways.
The objective of the bioassays is to determine if there are any
potential risks of toxicological impacts from the sediment to the marine biota
and whether there is any difference in the toxicity of the sediments samples
and the reference sediment (collected from clean areas).
Sediment ecotoxicity testing will be conducted using three bioassays (using amphipod, polychaete and bivalve larvae) defined in the ETWBTCW34/2002. The species used in the bioassays are listed in Table 1. All tests will be initiated within the allowable holding period for the sediments as recommended by both international testing and programmes adopted locally (ie eight weeks) ([2]).
Table 1 Sediment
Toxicity Test Species
|
Test |
Species |
|
Amphipod (Solid-phase) |
Leptocheirus
plumulosus |
|
Polychaete (Solid-phase) |
Neanthes
arenaceodentata |
|
Bivalve Larvae (Water-soluble
phase) |
Crassostrea
gigas |
10. Control Sediment
The control
sediment will be used to evaluate background behaviour of the test organism such
as mortality, behaviour and development.
The results from the control sediment will be used to assess the
condition (health) of the test organisms and verify the acceptability of the
sediment bioassay using pre-defined criteria (eg
should > 10% mean mortality occur in the control sediment in the amphipod
test then the test must be repeated as the result indicates that the batch of
test organisms were in poor health and may not provide a true indication of the
potential for toxicity in the Impact sediment).
11. Statistical Methodology and
Interpretation of Test Results
The null hypothesis examined for this project is:
H0 There are no differences between toxicity of the contaminated sediments and the Reference sediments.
One-way ANOVA will be performed to examine any differences in test organism response when exposed to the sediment in the six treatments. Statistically significant differences is determined at a probability, p≤0.05.
Amphipod Test - a biologically significant toxic response is considered to be: amphipod mortality that is significantly different (p≤0.05) between the Reference sediment and the sample, and, mean survival in the test sediment <80% of mean survival in Reference sediment ([3]).
Bivalve Larval Test - a biologically significant toxic response is defined as: corrected abnormality or combined mortality that is statistically different (p≤0.05) between the Reference Sediment and the sample, and, mean normality survival in the test sediment <80% of mean survival in reference sediment ([4])([5]).
Polychaete Test - a biologically significant toxic response is an individual growth rate that is recorded when: Mean dry weight in test sediments is significantly different (p≤0.05) from mean dry weight in Reference sediment , and, mean dry weight in test sediments <90% of mean dry weight in Reference sediment ([6])([7]).
12. Final Classification and Disposal
The final classification decision and selection of
appropriate disposal options, routing and the allocation of a permit to dispose
at the designated disposal site will be made by the EPD, in consultation with
the Marine Fill Committee (MFC) in accordance with WBTC 12/2000 ([8]).
([1]) This sampling plan is based on the fact that
no reclamation is required for the proposed development.