KTAC BSQR2004-05

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CHEC-OWT JOINT VENTURE-

CEDD CONTRACT NO. CV/2004/05MAINTENANCE DREDGING (2005-08)

W.O. No.: MD/33/04

BASELINE SEDIMENT QUALITY REPORT(BSQR)

AT

KAI TAK APPROACH CHANNEL (KTAC)

DATE STATUS /REVISION DESCRIPTIONSPREPARED

BY:VERIFIED &

APPROVED BY:

24.11.2005 First Issue CTK/JAL LC

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Maintenance Dredging (2005-08) November 2005

Contract No. CV/2004/05

CHEC-OWT Joint Venture BSQR

Page 1 of 11

1. INTRODUCTIONAccording to the requirements of W.O. No. MD/33/04, sediment sampling

and testing at Kai Tak Approach Channel (KTAC) was to be carried out to

assess the sediments physical, chemical and biological properties and hence

level of contamination prior to sediment treatment. The results of the

sampling events are presented in this Baseline Sediment Quality Report

(BSQR).

Information contained in this ISQR includes:

1. Layout of the sampling locations;2. Summary of test results on site and in laboratories; and3. Detailed laboratory analytical reports.

2. METHODOLOGYThe approximate extent of treatment is 1 hectare. All works described in this

report were carried out in accordance with the methods detailed in the Works

Order, or specified otherwise. A location plan of the proposed treatment areaand sampling locations is attached inAppendix A . All samples were taken in

presence of representative(s) from Civil Engineering and Development

Department (CEDD). All field observations and in-situ measurement results

were also recorded in Sediment Monitoring Data Sheets (SMDS), which is

presented inAppendix B .

Measurements of pH and redox were carried out in-situ for samples at all

depths. Those sediments collected at the depth of 10 - 30 cm were stored in

0.25 L brown glass jars and plastic bags, and were labeled for further

laboratory analysis. Sediments were also collected at the depth of 40 - 60 cm

and 70 - 90cm (if sediment samples were available) for AVS analysis. Details

of laboratory analytical methodologies and the associated detection limits are

summarized inAppendix C. All samples were delivered to laboratory on the

same date of sampling, under the custody of CEDDs representatives.

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3. RESULTSThe following paragraphs provide discussions of the in-situ and laboratory

analytical results. A tabulated summary of monitoring results is given in

Appendix D, whereas the detailed analytical reports are presented in

Appendix E.

3.1 Field Observations

The sediment sampling was carried out on 22nd September 2005. It was

sunny throughout the sampling event.

The thickness of penetrable sediments varied between 0.69 to 0.99 m.

Almost all of the cores were black in color and soft in texture. Leaves

were noted to have been trapped in some of the cores. Most cores were

also noted to have very strong hydrogen sulphide smell at the sediment

surface, and decreasing towards the bottom.

No clear sediment and water interface was seen during sediment

sampling. Sediments were seen loose and fluffy, with a thickness ofapproximately 0.2 0.3 m.

3.2 Field Measurements

3.2.1 pH

The following values were recorded on pH:

Average pHArea

10 - 30 cm 40 - 60 cm 70 - 90 cm

A1 6.72 6.69 6.77A2 6.84 7.09 7.03

A3 6.82 6.77 6.84A4 6.70 6.75 6.71

Average 6.77 6.82 6.84

The pH values for individual cores at the monitoring locations

ranged from a minimum of 6.48 at Area A1 (A1-0-b) to a

maximum of 8.86 at Area A2 (A2-0-a), with an average value of

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6.79.

3.2.2 Redox

The following values were recorded on redox:

Average Redox (mV)Area

10 - 30 cm 40 - 60 cm 70 - 90 cm

A1 -438 -384 -340A2 -326 -296 -261

A3 -465 -388 -368

A4 -445 -433 -391

Average -418 -375 -340

Redox values provide an indication of the biochemical

conditions within the sediments and the lower the redox value,

the greater the potential of odour problems.

The highest and the lowest average redox measurement on

individual cores are 694 mVin core A1-0-d and -201 mV in

A2-0-a, with an average value of 378 mV.

3.3 Chemical Analytical Results

3.3.1 Acid Volatile Sulphide (AVS)

AVS (mg/kg dry wt.)Area

10 - 30 cm 40 - 60 cm 70 - 90 cm

A1 5,500 6,975 8,950A2 6,300 7,975 9,050

A3 6,500 8,550 7,925

A4 7,000 8,075 8,250

Average 6,325 7,894 8,544

The recorded acid volatile sulphide (AVS) concentrations

ranged from 5,500 mg/kg in Area A1 to 9,050 mg/kgin Area A2,

with an average value of 7,588 mg/kg.

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3.3.2 Nitrate Nitrogen (NO3-N)

Area Nitrate Nitrogen*

(mg NO3 -N /L wet)A1

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^UCEL (Upper Chemical Exceedace Level) and LCEL (Lower Chemical Exceedance

Level) as stated in Works Bureau Technical Circular No. 3/2000 Management of

Dredged / Excavated Sediment.

The highest and the lowest heavy metal contents were generally

found in Area A3 and Area A4 respectively. The analytical

results were also compared with the Sediment Quality Criteria

as listed in the Works Bureau Technical Circular No. 3/2000

Management of Dredged / Excavated Sediment. All samples

have exceedance of UCEL with most of the heavy metals, except

for arsenic.

3.3.5 Heavy Metals in Sediment Interstitial Water (Elutriate Test)Heavy Metals (g/L)Area

Cr Cu Zn

A1

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LCEL < value < UCEL

Value > UCEL

* Result represents samples collected from 10-30 cm section.

^UCEL (Upper Chemical Exceedace Level) and LCEL (Lower Chemical Exceedance

Level) as stated in Works Bureau Technical Circular No. 3/2000 Management of

Dredged / Excavated Sediment.

Low molecular weight polyaromatic hydrocarbons (LMW

PAHs) concentrations in sediment were below the detection

limit (55g/kg) in all sampling areas nor the criteria as stated in

the Technical Circular.

3.3.7 High Molecular Weight Polyaromatic Hydrocarbons (HMWPAHs)

Area HMW PAHs *(g/kg dry wt.)

LCEL^(g/kg dry wt.)

UCEL^(g/kg dry wt.)

A1

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3.3.8 Total Polychlorinated Biphenyls (Total PCBs)Area Total PCBs *

(g/kg dry wt.)

LCEL^

(g/kg dry wt.)

UCEL^

(g/kg dry wt.)A1

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Page 8 of 11

as stated in the Technical Circular.

3.4 Biological Analytical Results

3.4.1 Microtox - Direct Sediment Contact

Area EC50 (%)

A1 0.01

A2 0.02

A3 0.04

A4 0.02

Average 0.02

Two tests were performed on the sediment samples, a direct

sediment contact bioassay and a saline extract bioassay. For the

sediment contact bioassays, the results showed that the EC50

ranged from 0.01% in Area A1 to 0.04% in Area A3, with an

average value of 0.02%.

3.4.2 Microtox - Saline Extract

Area Luminescence Ratio (L.R.)

A1 0.85

A2 0.71

A3 0.72

A4 0.78

Average 0.76

The results of the saline extract showed no significant toxicity to

allow for calculation of EC50. The Luminescence Ratio (L.R.) is

used to assess the potential change in sediment toxicity. The

pre-treatment L. R. ranged from 0.71 in Area A2 to 0.85 in Area

A1 with an average value of 0.76.

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3.4.3 10-day Burrowing Amphipod Toxicity TestArea 10-day Burrowing Amphipod

Toxicity Test (mean % survival)A1 0

A2 0

A3 0A4 0

Average 0

The results showed that 0% of amphipods survived the 10-day

toxicity test in all sampling areas.

3.4.4 20-day Burrowing Polychaete Toxicity TestArea 20-day Burrowing Polychaete

Toxicity Test (mean % survival)

A1 0A2 0

A3 0

A4 0

Average 0

The results showed that 0% of polychaete survived the 20-day

toxicity test in all sampling areas.

3.4.5 48-96-hour Bivalve LarvaeArea 48-96-hour Bivalve Larvae

(mean normality survival %)

A1 0A2 0

A3 0

A4 0

Average 0

The results showed that 0% of bivalve larvae survived the

48-96-hour toxicity test in all sampling areas.

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4. ConclusionsThis ISQR presents the results of sediment samplings in Kai Tak Approach

Channel. The overall findings and conclusions are summarized in the

following Table 1:

Parameter /Unit Min Max Average

Core Length(m)

0.69 0.99 0.87

pH

10 30 cm 6.53 6.90 6.77

40 60 cm 6.52 8.86 6.82

70 90 cm 6.61 7.25 6.84Redox

10 30 cm -694 -201 -418

40 60cm -641 -229 -375

70 90 cm (mV) -506 -230 -369

AVS(mg/kg dry wt.)

5,500 7,000 6,325

NO3-N(mg /L wet vol.)

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Parameter /Unit Min Max Average

LMW PAHs(g/kg dry wt.)

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APPENDIX A

LOCATION PLAN O F

SEDIMENT SAMPLING LO CATIONS

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Table A Coordinates of Sampling Locat ions

Sampling

Location I.D. Northing Easting

A1 820 062 838 929

A2 820 027 838 964

A3 820 026 838 894

A4 819 991 838 930

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APPENDIX B

SEDIMENT MO NITOR ING DA TA SHEETS

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APPENDIX C

LABOR ATO RY AN ALYTICAL METHODOLO GIES

& DETECTION LIMITS

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Table C Analy ti cal Methodologies and Detection Limit s

Parameters Determination Method

Detection

Limit

Acid Volatile Sulphide(AVS)

"Diffusion Method for theDetermination of Acid-Volatile Sulphidein Sediment" H Brouwer & T.P. Murphy,Env. Toxicology & Chemistry, Vol 13,No. 8, pp 1273-1275, 1994

1 mg/kg

Nitrate-Nitrogen(NO3-N)

APHA 4500 NO3-N E and 4500-NO2- B 1 mg/kg

Microtox Microtox operating Manual - SalineExtract & Solid Phase Test

N/A

Chromium USEPA 6020A 8 mg/kg

Cadmium USEPA 6020A 0.2 mg/kgCopper USEPA 6020A 7 mg/kgMercury USEPA 6020A 0.05 mg/kgNickel USEPA 6020A 4 mg/kgLead USEPA 6020A 8 mg/kgSilver USEPA 6020A 0.1 mg/kgZinc USEPA 6020A 20 mg/kgArsenic USEPA 6020A 1 mg/kgChromium(in interstititial water)

W/DIG/RAR & M/ICP-MS 1 g/L

Copper(in interstititial water)


Zinc

(in interstititial water)


Total Organic Carbon(TOC)

APHA 5310B 0.05 % w/w

Low Molecular WeightPAHs

USEPA 8270C 55 g/kg

High Molecular WeightPAHs

USEPA 8270C 170 g/kg

Total PCBs USEPA 8270C 2 g/kg

Tributyltin UNEP/IOC/IAEA 0.015 g/L

Amphipod Test USEPA 1994 N/A

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Parameters Determination MethodDetection

Limit

Polychaete Test PSEP 1995 N/A

Bivalve Test PSEP 1995 N/A

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APPENDIX D

TABULATED SUMMA RY OF MO NITOR ING RESULTS

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APPENDIX E

LABORA TORY AN ALYTICAL REPORTS

Documents

KTAC BSQR2004-05