Appendix 7.4 Methodology for Cumulative Ecological Risk Impact Assessments
1.1 The assessment approach for the cumulative risk impact was same as the one for the Ecological Risk Assessment (ERA) for the chlorination by-products (CBPs), which has been discussed in Appendix 7.1.
Problem Formulation
1.2 The objective, scope, Site Conceptual Model and assessment endpoints of the cumulative risk impact assessment are same to those for ERA, which have been presented in Section 7 and Appendix 7.1.
1.3 The cumulative risk impact assessment focused on assessing the potential risks/impacts to ecological resources due to chronic exposure to the CBPs and other pollutants present in the HATS effluent discharge.
Identification of COPC and Selection of COC
Identification of COPC
1.4 A comprehensive chemical analysis was conducted under the HATS EEFS Ecological and Health Risk Assessment (2004) to determine the pollutant concentrations in HATS CEPT effluent (Stage 1 and Stage 2A) and CEPT plus Biological Aerated Filters (BAF) effluent (Stage 2B). One hundred of analytes including metals, inorganic pollutants, organic pollutants, pesticides and organo-metallics were identified as COPC and analyzed.
1.5 A number of selection rules were established in HATS EEFS Ecological and Health Risk Assessment (2004) for selection of COCs and determination of COC effluent concentrations for risk assessments. COCs selected for Project Scenarios 1 to 3 and Scenario 4 for cumulative risk impact assessment are presented in Tables 1 and 2 respectively.
Table 1 Results of COCs Selection for Scenarios 1 to 3
|
|
Selected as COC for |
|
|
|
|||
|
COPC |
ERA – Aquatic Life |
ERA – Marine Mammals |
Max. Conc. in CEPT Effluent (mg/L)* |
Max. Conc. in Ambient Seawater (mg/L)* |
Note |
|
|
|
Aluminium |
Yes |
Yes |
15.9 |
15.6 |
|
|
|
|
Antimony |
Yes |
Yes |
0.721 |
0.258 |
|
|
|
|
Arsenic |
|
|
1.2 |
1.36 |
|
|
|
|
Barium |
Yes |
Yes |
23.2 |
6.65 |
|
|
|
|
Chromium III |
Yes |
Yes |
9.58 |
0.28 |
|
|
|
|
Copper |
Yes |
Yes |
8.59 |
0.02 |
|
|
|
|
Lead |
Yes |
Yes |
0.128 |
0.055 |
|
|
|
|
Mercury |
|
|
9.58ng/L |
0.06ng/L |
A |
|
|
|
Nickel |
Yes |
Yes |
26.2 |
0.77 |
|
|
|
|
Selenium |
Yes |
Yes |
0.31 |
0.07 |
|
|
|
|
Silver |
Yes |
Yes |
0.182 |
0.006 |
|
|
|
|
Tin |
Yes |
Yes |
0.844 |
0.14 |
|
|
|
|
Vanadium |
Yes |
Yes |
29.5 |
1.73 |
|
|
|
|
Zinc |
Yes |
Yes |
14.1 |
2.37 |
|
|
|
|
Ammonia |
Yes |
Yes |
22,000 |
230 |
|
|
|
|
Sulphide |
Yes |
Yes |
4,900 |
48 |
|
|
|
|
TCDD (I-TEQ) |
Yes |
Yes |
0.1pg/L |
0.039pg/L |
|
|
|
|
Toluene |
Yes |
Yes |
12 |
<1 |
|
|
|
|
Diazinon |
Yes |
Yes |
0.048 |
<0.01 |
|
|
|
|
Malathion |
Yes |
Yes |
0.031 |
<0.01 |
|
|
|
Note: * Dissolved concentration of metal for ecological risk assessment
A) Rinsate blank of dissolved mercury is greater than 20% of sample value
Table 2 Results of COCs Selection for Scenario 4
|
|
Selected as COC for |
|
|
|
|
|
COPC |
ERA – Aquatic Life |
ERA – Marine Mammals |
Max. Conc. in secondary treated Effluent (mg/L)* |
Max. Conc. in Ambient Seawater (mg/L)* |
Note |
|
Aluminium |
|
|
6.7 |
15.6 |
|
|
Antimony |
Yes |
Yes |
0.782 |
0.258 |
|
|
Arsenic |
|
|
1.0 |
1.36 |
|
|
Barium |
Yes |
Yes |
23.7 |
6.65 |
|
|
Chromium III |
Yes |
Yes |
8.44 |
0.28 |
|
|
Copper |
Yes |
Yes |
6.63 |
0.02 |
|
|
Lead |
|
|
0.055 |
0.055 |
|
|
Mercury |
|
|
1.61ng/L |
0.06ng/L |
A |
|
Nickel |
Yes |
Yes |
22.3 |
0.77 |
|
|
Selenium |
Yes |
Yes |
0.13 |
0.07 |
|
|
Silver |
Yes |
Yes |
0.099 |
0.006 |
|
|
Tin |
Yes |
Yes |
0.457 |
0.14 |
|
|
Vanadium |
Yes |
Yes |
31.3 |
1.73 |
|
|
Zinc |
Yes |
Yes |
9.79 |
2.37 |
|
|
Ammonia |
Yes |
Yes |
4,200 |
230 |
|
|
Sulphide |
Yes |
Yes |
53 |
48 |
|
|
TCDD (I-TEQ) |
Yes |
Yes |
0.062pg/L |
0.039pg/L |
|
|
Toluene |
|
|
<1 |
<1 |
|
|
Diazinon |
Yes |
Yes |
0.058 |
<0.01 |
|
|
Malathion |
Yes |
Yes |
0.015 |
<0.01 |
|
Note: * Dissolved concentration of metal for ecological risk assessment
A) Rinsate blank of total and dissolved mercury is greater than 20% of sample value
Ecological Risk Assessment – Aquatic Life
1.6 The exposure assessment is same to the one for ERA – Aquatic Life for CBPs.
1.7 Table 3 summarized the averaging time of different TRVs and the corresponding dilution factor for COC concentration calculation.
Table 3 Averaging Time of TRVs and Corresponding Dilution Factor
|
TRV Averaging Time |
Dilution Factor at Edge of ZID |
Dilution Factor at Edge of Mixing Zone |
|
Daily |
Minimum dilution factor in dry and wet season |
Minimum dilution factor in dry and wet season |
|
4-day |
Minimum dilution factor in dry and wet seasona |
Minimum 4-day dilution factor in dry and wet season |
|
Annual |
Annual weighted average dilution factor |
Annual weighted average dilution factor |
|
“To be complied at least 90% of occasions” |
10 %tile dilution factor in dry and wet seasonb |
10 %tile dilution factor in dry and wet seasonb |
|
Seasonalc |
The lower value of weight average dilution factor estimated for dry season and that of wet season |
The lower value of weight average dilution factor estimated for dry season and that of wet season |
Note: a Minimum dilution factor was adopted as a conservative estimate
b Dilution factor exceeded 90% of the time (i.e. 10% of values are below this value)
c For COC without water quality standard/criteria, which TRV was derived from toxicity data
Ecological Risk Assessment – Marine Mammals
1.8 The exposure assessment is same to the one for ERA – Marine Mammals for CBPs
1.9 Bioconcentration factor and food chain multiplier for COCs were presented in Table 4.
Table 4 Bioconcentration Factor and FCM
|
COC |
Water-to-fish Bioconcentration Factora |
Trophic Level 4 FCMb |
Water-to-aquatic invertebrates Bioconcentration Factor |
Trophic Level 3 FCMb |
|
Aluminum |
2.7 |
1.0 |
0.13c |
1.0 |
|
Antimony |
40 |
1.0 |
7d |
1.0 |
|
Barium |
633 |
1.0 |
200d |
1.0 |
|
Chromium (III) |
19 |
1.0 |
0.11c |
1.0 |
|
Copper |
710 |
1.0 |
3,718d |
1.0 |
|
Lead |
0.09 |
1.0 |
5,059d |
1.0 |
|
Nickel |
78 |
1.0 |
28d |
1.0 |
|
Selenium |
129 |
1.0 |
1,262d |
1.0 |
|
Silver |
87.7 |
1.0 |
298d |
1.0 |
|
Tin |
138 |
1.0 |
138e |
1.0 |
|
Vanadium |
N/A |
- |
N/A |
- |
|
Zinc |
2,060 |
1.0 |
4,758d |
1.0 |
|
Ammonia |
N/A |
- |
N/A |
- |
|
Sulphide |
N/A |
- |
N/A |
- |
|
Dioxins and furans (TEQ) |
34,400 |
27 |
1,560d |
14 |
|
Toluene |
171 |
1.0 |
11.6c |
1.0 |
|
Diazinon |
171 |
1.0 |
94.3c |
1.2 |
|
Malathion |
13.1 |
1.0 |
6.12c |
1.0 |
N/A: Not Available
Note: a Also refer to Table 3 of Appendix 6II.3.
b The FCMs were developed using Kow values reported in USEPA (1995), as in USEPA (1999b).
c No recommended BCF value identified. Regression equation was used to calculate the BCF values (Southworth et al. (1978), as in USEPA (1999b)).
d Recommended BCF value in USEPA (1999b).
e MW (1998).
Ecological Effects Characterization (for ERA – Aquatic Life)
1.10 The ecological effects of COC exposure to aquatic life were characterized by comparing the COC concentrations in the seawater at the edge of the ZID and the edge of the mixing zone to the TRV for aquatic life. TRVs for COCs were derived from water quality criteria/standards for protection of aquatic life when available; for COCs without such criteria/standards, toxicity values obtained from the scientific literature were used to derive TRVs. Details on the TRV derivation process were presented in Annex B; derived TRVs for risk calculations were presented in Table 5.
Table 5 Derived TRVs for Aquatic Life
|
COC |
TRV for ecological resources (μg/L) |
Averaging Time |
|
Aluminium |
1500 |
Annual average |
|
Antimony |
4300 |
Annual average |
|
Barium |
5000 |
Seasonal average |
|
Chromium III |
27.4 |
Annual average |
|
Copper |
5 |
Not to exceed at 10% of occasions |
|
Lead |
8.1 |
4-day average |
|
Nickel |
5 |
Not to exceed at 10% of occasions |
|
Selenium |
71 |
4-day average |
|
Silver |
1.4 |
Annual average |
|
Tin |
81.6 |
Seasonal average |
|
Vanadium |
100 |
Annual average |
|
Zinc |
20 |
Not to exceed at 10% of occasions |
|
Ammonia |
910 |
Annual average |
|
Sulphide |
100 |
Seasonal average |
|
TCDD |
0.000038 |
Seasonal average |
|
Toluene |
40 |
Annual average |
|
Diazinon |
0.01 |
Annual average |
|
Malathion |
0.02 |
Annual average |
a No recommended UF factor to convert subchronic lethal level to chronic NOEC; the adopted UF of 0.01 was considered to be conservative.
Ecological Effects Characterization (for ERA – Marine Mammals)
1.11 The ecological effects of COC exposure to marine mammals were characterized by comparing the COC daily dose to the toxicity reference doses for the marine mammals, which were derived by reviewing the toxicological effects data from various scientific literature, database and guidelines. Details on the toxicity reference dose derivation process were presented in Annex C; derived toxicity reference dose for risk calculations were presented in Table 6.
Table 6 Derived Toxicity Reference Dose for Marine Mammals
|
COC |
Toxicity Reference Dose Derived (mg/kg/d) |
|
Aluminum |
6.125 |
|
Antimony |
0.015625 |
|
Barium |
1.875 |
|
Chromium (III) |
342.125 |
|
Copper |
1.5 |
|
Lead |
1 |
|
Nickel |
5 |
|
Selenium |
0.02625 |
|
Silver |
2.7775 |
|
Tin |
2.925 |
|
Vanadium |
0.02625 |
|
Zinc |
20 |
|
Ammonia |
5.15 |
|
Sulphide |
No toxicological data available |
|
Dioxins and furans (TEQ) |
8.875E-6 |
|
Toluene |
3.25 |
|
Diazinon |
1.5 |
|
Malathion |
4.4875 |
Risk/Hazard Characterization
1.12 The risk/hazard characterization for the cumulative risk impact was same as the risk assessments for the CBPs.
References
For Ecological Risk Assessment – Aquatic Life
1. ANZECC (2000). Australian and New Zealand Guidelines for Fresh and Marine Water Quality.
2. CCME (2003). Canadian Environmental Quality Guidelines – Summary Table. Available online: www.ec.gc.ca/ceqg-rcqe/english/default.cfm
3. CDM (2002). Environmental and Engineering Feasibility Assessment Studies in Relation to the Way Forward of the Harbour Area Treatment Scheme – Proposed Water Quality Critieria.
4. CDM (2004). Environmental and Engineering Feasibility Assessment Studies in Relation to the Way Forward of the Harbour Area Treatment Scheme – Working Paper No. 8 Ecological and Human Health Risk Assessment (Final).
5. IPCS INCHEM. OECD Screening Information DataSet High Production Volume Chemicals. Available online: www.inchem.org/pages/sids.html.
6. Montgomery Watson (1998). Strategic Sewage Disposal Scheme – Environmental Impact Assessment Study – Technical Note 4. Detailed Risk Assessment (Final Version).
7. PRC National Guideline – Environmental Quality Standards for Surface Water (GB 3838-2002).
8. USEPA. ECOTOX Database. Available online: www.epa.gov/ecotox.
9. USEPA. Water Quality Standards – State, Tribal & Territorial Standards. Available online: www.epa.gov/waterscience/standards/states.
10. USEPA (1998). Guidelines for Ecological Risk Assessment.
11. USEPA (1999b). Screening Level Ecological Risk Assessment Protocol for Hazardous Waste Combustion Facilities.
12. USEPA (2004). National Recommended Water Quality Criteria.
13. WRc Swindon (1999). Guidelines for Managing Water Quality Impacts within UK European Marine Sites.
For Ecological Risk Assessment – Marine Mammals
14. ATSDR (1990). Toxicological Profile for Silver.
15. ATSDR (1992). Toxicological Profile for Antimony.
16. ATSDR (1992). Toxicological Profile for Vanadium.
17. ATSDR (1996). Toxicological Profile for Diazinon.
18. ATSDR (1998). Toxicological Profile for Chlorinated Dibenzo-p-dioxins (CDDs).
19. ATSDR (2000). Toxicological Profile for Chromium.
20. ATSDR (2003). Toxicological Profile for Malathion.
21. ATSDR (2004). Toxicological Profile for Ammonia.
22. ATSDR (2004). Toxicological Profile for Selenium.
23. ATSDR (2004). Toxicological Profile for Copper
24. ATSDR (2005). Toxicological Profile for Barium.
25. ATSDR (2005). Toxicological Profile for Lead.
26. ATSDR (2005). Toxicological Profile for Nickel.
27. ATSDR (2005). Toxicological Profile for Tin and Tin Compounds
28. ATSDR (2005). Toxicological Profile for Zinc.
29. CDM (2004). Environmental and Engineering Feasibility Assessment Studies in Relation to the Way Forward of the Harbour Area Treatment Scheme – Working Paper No. 8 Ecological and Human Health Risk Assessment (Final).
30. Montgomery Watson (1998). Strategic Sewage Disposal Scheme – Environmental Impact Assessment Study – Technical Note 4. Detailed Risk Assessment (Final Version).
31. NHMRC (2004). Australian Drinking Water Guidelines 2004.
32. ORNL (1996). Toxicological Benchmarks for Wildlife: 1996 Revision.
33. Sample, B.E., Opresko, D.M. and Suter II, G.W. (1996). Toxicological Benchmarks for Wildlife: 1996 Revision.
34. USEPA. Integrated Risk Information System. Available online: www.epa,gov/iris
35. USEPA (1999). Screening Level Ecological Risk Assessment Protocol for Hazardous Waste Combustion Facilities.
36. WHO (2004). Guidelines for Drinking-water Quality (Third Ed.) – Volume 1.