9 LAND CONTAMINATION

9.1 Environmental Legislation and Guidelines

9.1.1 The relevant legislations, standards and guidelines applicable to the present study for the assessment of land contamination include:

(1) Annex 19 of the TM-EIA, Guidelines for Assessment of Impact Assessment Process (TM-EIA), Guidelines for Assessment of Impact On Sites of Cultural Heritage and Other Impacts (Section 3 : Potential Contaminated Land Issues), EPD, 1997;

(2) Guidance Manual for Use of Risk-Based Remediation Goals (RBRGs) for Contaminated Land Management, EPD, 2007.

(3) Guidance Notes for Contaminated Land Assessment and Remediation EPD, 2007 ; and

(4) Practice Guide for Investigation and Remediation of Contaminated Land, EPD, 2011.

Environmental Impact Assessment Ordinance (EIAO) (Cap. 499), Technical Memorandum on Environmental Impact Assessment Process (TM-EIAO)

9.1.2 Under Annex 19 of the TM-EIAO, a number of potentially contaminating historical land uses should be considered, including oil installations, gas works, metal workshops, car repair and dismantling workshops, which have the potential to cause or have caused land contamination.

Guidance Manual for Use of Risk-Based Remediation Goals (RBRGs) for Contaminated Land Management

9.1.3 The Guidance Manual introduces the risk based approach in land contamination assessment and present instructions for comparison of soil and groundwater data to the RBRGs for 54 chemicals of concern commonly found in Hong Kong. The RBRGs were derived to suit Hong Kong conditions by following the international practice of adopting a risk-based methodology for contaminated land assessment and remediation and were designed to protect the health of people who could potentially be exposed to land impacted by chemicals under four broad post restoration land use categories. The RBRGs also serve as the remediation targets if remediation is necessary. The RBRGs for soil and groundwater are given in Tables 9.1 and 9.2 respectively.

Table 9.1: Risk-Based Remediation Goals (RBRGs) for soil & soil saturation limit

Chemical	Risk-Based Remediation Goals (RBRGs) for Soil				Soil Saturation Limit (C_sat)
	Urban Residential	Rural Residential	Industrial	Public Parks	Soil Saturation Limit (C_sat)
	(mg/kg)	(mg/kg)	(mg/kg)	(mg/kg)	(mg/kg)
VOCs
Acetone	9,590	4,260	10,000*	10,000*	***
Benzene	0.704	0.279	9.21	42.2	336
Bromodichloromethane	0.317	0.129	2.85	13.4	1,030
2-Butanone	10,000*	10,000*	10,000*	10,000*	***
Chloroform	0.132	0.0529	1.54	253	1,100
Ethylbenzene	709	298	8,240	10,000*	138
Methyl tert-Butyl Ether	6.88	2.80	70.1	505	2,380
Methylene Chloride	1.30	0.529	13.9	128	921
Styrene	3,220	1,540	10,000*	10,000*	497
Tetrachloroethene	0.101	0.0444	0.777	1.84	97.1
Toluene	1,440	705	10,000*	10,000*	235
Trichloroethene	0.523	0.211	5.68	69.4	488
Xylenes (Total)	95.0	36.8	1,230	10,000*	150
SVOCs
Acenaphthene	3,510	3,280	10,000*	10,000*	60.2
Acenaphthylene	2,340	1,510	10,000*	10,000*	19.8
Anthracene	10,000*	10,000*	10,000*	10,000*	2.56
Benzo(a)anthracene	12.0	11.4	91.8	38.3
Benzo(a)pyrene	1.20	1.14	9.18	3.83
Benzo(b)fluoranthene	9.88	10.1	17.8	20.4
Benzo(g,h,i)perylene	1,800	1,710	10,000*	5,740
Benzo(k)fluoranthene	120	114	918	383
Bis-(2-Ethylhexyl)phthalate	30.0	28.0	91.8	94.2
Chrysene	871	919	1,140	1,540
Dibenzo(a,h)anthracene	1.20	1.14	9.18	3.83
Fluoranthene	2,400	2,270	10,000*	7,620
Fluorene	2,380	2,250	10,000*	7,450	54.7
Hexachlorobenzene	0.243	0.220	0.582	0.713
Indeno(1,2,3-cd)pyrene	12.0	11.4	91.8	38.3
Naphthalene	182	85.6	453	914	125
Phenanthrene	10,000*	10,000*	10,000*	10,000*	28.0
Phenol	10,000*	10,000*	10,000*	10,000*	7,260
Pyrene	1,800	1,710	10,000*	5,720
Metals
Antimony	29.5	29.1	261	97.9
Arsenic	22.1	21.8	196	73.5
Barium	10,000*	10,000*	10,000*	10,000*
Cadmium	73.8	72.8	653	245
Chromium III	10,000*	10,000*	10,000*	10,000*
Chromium VI	221	218	1,960	735
Cobalt	1,480	1,460	10,000*	4,900
Copper	2,950	2,910	10,000*	9,790
Lead	258	255	2,290	857
Manganese	10,000*	10,000*	10,000*	10,000*
Mercury	11.0	6.52	38.4	45.6
Molybdenum	369	364	3,260	1,220
Nickel	1,480	1,460	10,000*	4,900
Tin	10,000*	10,000*	10,000*	10,000*
Zinc	10,000*	10,000*	10,000*	10,000*
Dioxins / PCBs
Dioxins (I-TEQ)	0.001	0.001	0.005	0.001
PCBs	0.236	0.226	0.748	0.756
Petroleum Carbon Ranges
C6 - C8	1,410	545	10,000*	10,000*	1,000
C9 - C16	2,240	1,330	10,000*	10,000*	3,000
C17 - C35	10,000*	10,000*	10,000*	10,000*	5,000
Other Inorganic Compounds
Cyanide, free	1,480	1,460	10,000*	4,900
Organometallics
TBTO	22.1	21.8	196	73.5

Notes:

[1] For Dioxins, the cleanup levels in USEPA Office of Solid Waste and Emergency Response (OSWER) Directive of 1998 have been adopted. The OSWER Directive value of 1 ppb for residential use has been applied to the scenarios of "Urban Residential", "Rural Residential", and "Public Parks", while the low end of the range of values for industrial, 5 ppb, has been applied to the scenario of "industrial".

[2] Soil saturation limits for petroleum carbon ranges taken from the Canada-Wide Standards for Petroleum Hydrocarbons in Soil, CCME 2000.

[3] * indicates a 'ceiling limit' concentration. A non risk-based ‘ceiling limit’ is given as 10⁴ mg/kg for soil and 10⁴ mg/L for groundwater for the relatively less toxic inorganic, volatile and semi-volatile contaminants.

[4] *** indicates that the Csat value exceeds the 'ceiling limit' therefore the RBRG applies.

Table 9.2: Risk-Based Remediation Goals (RBRGs) for groundwater and solubility limit

Chemical	Risk-Based Remediation Goals (RBRGs) for Groundwater			Groundwater Solubility Limit
	Urban Residential	Rural Residential	Industrial	Groundwater Solubility Limit
	(mg/L)	(mg/L)	(mg/L)	(mg/L)
VOCs
Acetone	10,000*	10,000*	10,000*	***
Benzene	3.86	1.49	54.0	1,750
Bromodichloromethane	2.22	0.871