4 Land Contamination Assessment

4.1 Introduction

This Section presents the assessment of potential land contamination impact associated with the demolition of the CCPP at the GICP. The assessment identifies the potential source of land contamination, summarises the intrusive site assessment findings and recommends mitigation measures, monitoring and audit programme to minimise potential environmental implications from demolition of the CCPP, and assesses potential residue impacts after the implementation of the mitigation measures.

A site appraisal of CCPP was carried out to identify potential sources of land contamination within the Project area and a Contamination Assessment Plan (CAP) was prepared outlining a programme for the intrusive site investigation at the CCPP to determine presence and extent (if any) of contamination at the Project area. References are made to potential land contamination that may be present due to the historical and current land uses of the Project area and the surroundings during the proposed demolition works and the proposed future uses of the Project area. The CAP was approved by the EPD in January 2008.

Land contamination site investigation was carried out in accordance with the CAP in February, 2008. Upon completion of the site investigation, a Contamination Assessment Report (CAR) was prepared detailing the investigation programme, on-site observations and the results of the soil sampling and testing. The CAR was endorsed by the EPD in May 2008.

This land contamination assessment has been undertaken in accordance with the requirements of Section 3.4.2 of the EIA Study Brief and makes reference to the CAP, dated 7 January 2008 (a copy of which is included in Annex A1) and the CAR, dated 11 April 2008 (a copy of which is included in Annex A2).

4.2 Legislative Requirements and Evaluation Criteria

As described in Section 1, the decommissioning of the CCPP is classified as a designated project under Item 3 of Part II Schedule 2 of the Environmental Impact Assessment Ordinance (EIAO) and hence it requires an EP prior to the decommissioning works.

Section 3.2.1 (ii) of the EIA Study Brief requires the EIA study to address likely issues associated with the land contamination due to past uses at the site. The brief requires the contamination impact to be evaluated and assessed as stipulated in Section 3 of Annex 19 of the Technical Memorandum on the Environmental Impact Process (EIAO-TM), issued under Section 16 of the EIAO. Annex 19 of the EIAO-TM: Guidelines for Assessment of Impact on Sites of Cultural Heritage and Other Impacts provides guidance on contamination assessment of potential contaminated land.

The assessment of land contamination sources and the potential impacts to particular development projects are guided by the EPD’s Guidance Manual for Use of Risk-based Remediation Goals (RBRGs) for Contaminated Land Management (the RBRG Guidance Manual), the associated Guidance Note for Contaminated Land Assessment and Remediation, and the EPD’s Guidance Notes for Investigation and Remediation of Contaminated Sites of Petrol Filling Stations, Boatyards, and Car Repair/Dismantling Workshop. The RBRGs were developed for four different post-restoration land-use scenarios. The Project Site is classified as an Industrial Site under the RBRGs.

Of particular relevance to the land contamination assessment for this Project is the concept of preparing a conceptual site model (CSM) for the site, which is referred to in The Guidance Manual for Use of Risk-based Remediation Goals for Contaminated Land Management. The guidance manual requires that a CSM is used to illustrate the potential sources of contamination, possible receptors and likely pathways linking the two.

In addition, reference has been made to the following documents published by the EPD.

· Waste Disposal Ordinance (Cap 354);

· Waste Disposal (Chemical Waste) (General) Regulation (Cap 354C);

· Code of Practice on the Packaging, Labelling and Storage of Chemical Wastes, EPD (1992); and

· Waste Disposal (Charges for Disposal of Construction Waste) Regulation (Cap 354N)

4.3 Site Conditions

The following sections describe the Project Site, its environmental setting and the CSM.

The following information is contained in the CAP in Annex A1 and referenced as deemed necessary.

4.3.1 Site Environmental Setting

The Project Site is surrounded by the following land uses.

· North: a lawn beyond which is situated a LPG store (to the northwest), and a container office (to the northeast);

· South: an internal road, beyond which is the Pulverised Fly Ash (PFA) Grinding and Classification system;

· East: the operating cement kiln; and

· West: an internal road, beyond which is situated a Pack House and cement silos (to the northwest) and to the southwest, underground fuel storage tanks.

The overall setting of the Green Island Cement Plant (GICP) within which the CCPP is situated is as follows.

· North: the Lung Mun Road;

· South: the sea;

· East: the Shiu Wing Steel works;

· West: the Castle Peak Power Station.

The GICP site is constructed on land reclaimed from the sea and as such the underlying groundwater is not considered to be a resource. Figures D1 and D2 of the CAP (see Annex A1) illustrate the fill materials underlying the GICP site, which appear to be natural hillside stone.

The whole CCPP site area was paved with concrete or asphalt during its operation. Figure B1 of the CAP shows the layout plan of the CCPP.

4.3.2 Description of Existing Conditions

Present Land Use and Activities of the CCPP

The operation of the CCPP commenced in October 2005 and was stopped in December 2005. No chemicals or hazardous substances were handled at the CCPP. Municipal Solid Waste (MSW) (eg paper, plastics, metals and putrescible materials) was delivered to the Materials Recovery/Recycling Facility (MRRF) by refuse collection vehicles. The waste was unloaded onto an impermeable concrete ground surface and then loaded to the MRRF to recover recyclable materials in the waste. The residual waste was shredded and fed to the co-combustion unit to recover energy from the waste. The flue gas from the combustion process was cleaned prior to discharge to the atmosphere.

The CCPP comprised the following key components:

· The MRRF which consisted of a waste reception hall, trommel screen, separators, shredder, belt conveyors and an underground wastewater storage tank. The wastewater was fed to the on-site wastewater treatment plant of the GICP for treatment and disposal;

· The Main Thermal Treatment System, which consisted of feed and combustion chambers, rotary kiln, pre-calciner, cyclones with tipping valves, bag house filter/dust collector, ash storage tank and heat exchanger among other items; and

· The Lime Cooling System, which consisted of a lime storage bin, feed bin, lime ejector, air blower and cyclone with tipping values.

The layout of the CCPP and location of potential sources of land contamination within the Study Area are shown in Figure B2 of the CAP. The possible land contamination sources are also shown in Figure B2 as the rotary kiln, secondary combustion chamber, bag house filter/dust collector and heat exchanger. These are all above ground structures where residues from the various activities may have collected. The wastewater storage tank could also contain residues of wastewater from the MRRF.

As mentioned above, all activities associated with the CCPP have ceased at the Project Site. During the short operation period (11 weeks) of the CCPP no accidents, leakages, spillages or other problems likely to cause land contamination were reported.

Historical Land Use and Activities

The Project Site is situated on an area of reclamation and was developed using fill materials from the nearby hillsides, see Figures D1 and D2 of the CAP.

Following start up of the cement plant in 1982, the Project Site was used for stockpiling of cement clinker until 1985. The Project Site was also used as an emergency open stockpile of natural limestone between 1990 and 1994. A propane storage area was reportedly built in the late 1980’s, but was never commissioned, and was removed in 1992.

Table 4.3a summarises the historical development of the GICP and CCPP. Further details of the historical land uses are provided in the Section 2.4 of the CAP.

Table 4.3a Site Historical of the GICP and CCPP Site

Time	GICP	CCPP Site
Late 1970s	Site reclamation	-
Before 1982	Construction of the cement plant	-
1982	Operation of the GICP cement kiln began	Reserved for propane storage and used as emergency stockpile of cement clinker until 1985
1984-1990	Operation of the cement kiln suspended	Reserved for propane storage and left vacant
1990-1994	Operation of the cement kiln restarted	Reserved for propane storage and used as emergency storage of limestone imported from Japan
1992	Continuous operation of the GICP	Propane storage was built but never commissioned. It was removed in March 1992
After 1994	Continuous operation of the GICP	Rehabilitated as a kiln lawn until the construction of CCPP
Dec 2001	Clinker production was suspended	Rehabilitated as a kiln lawn until the construction of CCPP
Jun 2004	Clinker production was suspended	Construction of the CCPP foundation
Apr 2005	Clinker production was suspended	First load commissioning test of the CCPP
Jul 2005	Clinker production was suspended	Second load commissioning test of the CCPP
Oct 2005	Clinker production was suspended	Continuous operation of the CCPP
Dec 2005	Clinker production was suspended	Operation ceased after all operation data has been collected
Jan 2006	Clinker production resumed	-

4.4 Potential Sources of Land Contamination at the Site

Based on the historical uses of the Project Site and the environmental setting described above, the following potential existing on and off-site sources of contamination that could affect the Project Site have been identified. They are described in the following sections.

4.4.1 Off-Site Sources

· The storage and transfer of fuel (diesel oil) at the fuel underground storage tanks (UST) and dispensing station located approximately 20m to the southwest of the Project Site. The USTs were reportedly constructed of single-shell steel encased in concrete with a minimum thickness of 150mm. In order to minimise risk of accidental oil leakages, tank piping pressure tests/hydraulic tests are conducted once every 5 years. The fuel dispensing station was used for filling of around 20 vehicles per day. The area was paved. The fuel UST and dispensing station will not be included in the proposed decommissioning of CCPP.

· Potential leakage of fuel from overhead fuel pipelines connecting the fuel oil storage tank (located approximately 100m to the southwest of the Project Site) with the CCPP and the main cement kiln. No evidence of leakage was observed during the site visit.

4.4.2 On-Site Sources

· The storage and handling of MSW used in the pilot tests. It is noted that prior to being fed into the rotary kiln, all the wastes were received, stored and sorted in the MRRF, which was an enclosed building with concrete floor. All leachate and wastewater generated in the building was collected in an enclosed drainage system leading to an UST and then transferred to the wastewater treatment plant of the GICP for treatment. The likelihood of the MSW or leachate / wastewater causing contamination below the impermeable concrete floor is considered to be negligible.

· Leakage and/or spillage from the UST for leachate generated from the MRRF. The UST is a steel tank and its integrity has been checked to ensure no leakage prior to use. The tank was used for a short period of time (11 weeks) during the operations of the CCPP and no evidence of leakage/damage was observed. Therefore the likelihood of the leachate / wastewater contaminating the soil around the tank and groundwater is considered to be very low. Moreover, the waste handled at the MRRF was MSW and the leachate generated from the operation of the MRRF would be expected to have been organic in nature and not expected to contain potential contaminants of concern such as heavy metals or persistent organic compounds.

· Leakage/spillage of contaminants from the ash generated from the rotary kiln system during the MSW incineration process. It is noted that all ash generated from the CCPP was collected from the kiln directly into bags and transferred for storage in the reception hall of the MRRF building. After the completion of the pilot test, the remaining ashes were vacuumed from the units and also collected in bags. Therefore it is unlikely that anything more than very limited fugitive ash was spilled on the paved floor of the reception hall. The likelihood of this ash then contaminating the soil or groundwater beneath the paved floor is considered to be negligible.

· Leakage/spillage of contaminants from bottom ash quenching tank located at the bottom of the rotary kiln. It is noted that the bottom ash was quenched, collected in bags and transferred for storage in the reception hall thus limiting the potential for the contamination of the underlying soils and groundwater to negligible levels.

Locations and photos of these potential sources are presented in the CAP (Annex A1).

The whole Project Site area was paved with concrete and asphalt. The wastewater from the MRRF was connected to a collection sump and was then transferred for treatment at GICP. The stormwater run-off from the outdoor plant area was collected within the GICP drainage system.

It was observed that the fuel oil transfer pipelines used overhead pipes. No oil, ash and wastewater spillage/leakage had reportedly occurred at the Project Site during its short period of operation and none were observed during the site visit.

Potential existing off-site sources of soil and groundwater contamination are associated with the current operation of the cement plant surrounding the Project Site. Further off-site, the potential sources may include the power station and a steel manufacturing plant which are also industrial use.

4.4.3 Potential Future Source

The Project Site’s future use remains industrial (manufacture of cement and cement related products) and is surrounded by remaining areas of the GICP. After decommissioning, the concrete and asphalt slab and concrete foundations and sub structures will be excavated, to a maximum depth of 1.5m. The whole Project Site will then be levelled using clean imported materials. The Project Site will remain as an open area for the operation and future development of the GICP. It is currently proposed that the surface of the clean imported materials will be rehabilitated into a grass lawn.

All traces of MSW and the associated CCPP will have been removed and there will not be a potential source of contamination present at the Project Site.

4.5 Land Contamination Site Investigation Programme

An intrusive contamination investigation was conducted at the Project Site, details of which are presented in the CAR (see Annex A2). The site investigation (SI) included:

· Excavation of six trial pits down to a maximum of 1.5m below ground level (m bgl), with two trial pits (S1/S2 and S3/S4) located adjacent to the wastewater UST and four trial pits (S5/S6, S7/S8, S9/S10 and S11/S12) located around the CCPP area to determine any soil contamination;

· Sampling of two (2) soil samples were taken from each sampling location at just below the concrete pavement and at between 1.0 to 1.5m bgl for laboratory analysis of potential contaminants plus QA/QC samples;

· Laboratory analysis of soil samples for heavy metals (including Antimony (Sb), Arsenic (As), Barium (Ba), Cadmium (Cd), Chromium III and VI (Cr III and Cr VI), Cobalt (Co), Nickel (Ni), Copper (Cu), Lead (Pb), Manganese (Mn), Mercury (Hg), Molybdenum (Mo), Nickel (Ni), Tin (Sn), and Zinc (Zn)); total petroleum hydrocarbons (TPH); and benzene, toluene, ethyl benzene, and xylene (BTEX); and

· Laboratory analysis of three soil samples for Polychlorinated biphenyls (PCBs) and Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) (see Annex A3).

4.5.1 Soil Analytical Results

The results of the laboratory analysis of the soil samples are presented in Tables 4.5a.

Levels of TPH analysed for all three carbon ranges were below the reported detection limits for all samples. Concentrations of BTEX were also below the reported detection limits at all locations. Levels of all metals analysed in all samples were well below the RBRG values. Levels of PCBs, dioxins and furans analysed in all samples were well below the RBRG values for soil in industrial area. Therefore, no concern of dioxins/ PCBs contamination in the soil is expected.

The detailed results of the laboratory analysis of the samples with the QA/QC information are presented in the CAR (Annex A2) and Annex A3 of this report.

Table 4.5a Soil Analytical Results (all results in mg/kg dry weight)

Parameters	LOR^(a)	S1	S2	S3	S4	S5	S6	S7	S8	S9	S10	S11	S12	S13^(b)	RBRG Industrial	Csat ^(d)
% Moisture Content	0.1	15.3	8.1	10.6	9.8	10.3	9.8	9.4	10.6	7.4	7.5	9.5	10.6	7.6	-	-
TPH
· C6-C8 Fraction	5	<5	<5	<5	<5	<5	<5	<5	<5	<5	<5	<5	<5	<5	1.00E+04	1.00E+03
· C9-C16 Fraction	200	<200	<200	<200	<200	<200	<200	<200	<200	<200	<200	<200	<200	<200	1.00E+04	3.00E+03
· C17-C35 Fraction	500	<500	<500	<500	<500	<500	<500	<500	<500	<500	<500	<500	<500	<500	1.00E+04	5.00E+03
Benzene	0.2	<0.2	<0.2	<0.2	<0.2	<0.2	<0.2	<0.2	<0.2	<0.2	<0.2	<0.2	<0.2	<0.2	9.12E+00	3.36E+02
Toluene	0.2	<0.2	<0.2	<0.2	<0.2	<0.2	<0.2	<0.2	<0.2	<0.2	<0.2	<0.2	<0.2	<0.2	1.00E+04	2.35E+02
Ethyl-benzene	0.2	<0.2	<0.2	<0.2	<0.2	<0.2	<0.2	<0.2	<0.2	<0.2	<0.2	<0.2	<0.2	<0.2	8.24E+03	1.38E+02
m,p-Xylene	0.4	<0.4	<0.4	<0.4	<0.4	<0.4	<0.4	<0.4	<0.4	<0.4	<0.4	<0.4	<0.4	<0.4	1.23E+03^(c)	1.50E+02^(c)
o-Xylene	0.2	<0.2	<0.2	<0.2	<0.2	<0.2	<0.2	<0.2	<0.2	<0.2	<0.2	<0.2	<0.2	<0.2	1.23E+03^(c)	1.50E+02^(c)
Priority Metal
· Antimony (Sb)	1	7	<1	5	<1	2	<1	1	<1	<1	<1	2	1	<1	2.61E+02	-
· Arsenic (As)	1	25	<1	25	<1	2	<1	1	<1	<1	<1	4	1	2	1.96E+02	-
· Barium (Ba)	0.5	110	30.4	109	23.1	53.4	23.1	41.5	29.4	22.8	21.1	60.4	35.8	24.5	1.00E+04	-
· Cadmium (Cd)	0.2	2.2	0.2	0.7	<0.2	0.6	<0.2	0.5	<0.2	<0.2	<0.2	0.6	0.7	<0.2	6.53E+02	-
· Chromium III (Cr III)	0.5	35.3	8.8	28.2	2.3	14.2	3	12.1	4.2	8.5	3.2	15.7	21.5	24.5	1.00E+04	-
· Chromium VI (Cr VI)	0.5	<0.5	<0.5	0.8	<0.5	<0.5	<0.5	<0.5	<0.5	<0.5	<0.5	<0.5	<0.5	1.2	1.96E+03	-
· Cobalt (Co)	0.5	11.5	3.2	14.6	2.7	3.9	3.4	5.2	2.6	2.3	1.4	4.3	3.7	3.5	1.00E+04	-
· Copper (Cu)	1	226	22	103	2	35	2	20	3	17	2	57	32	30	1.00E+04	-
· Lead (Pb)	1	85	42	35	61	54	59	46	42	51	42	49	42	47	2.29E+03	-
· Manganese (Mn)	0.5	152	452	447	296	279	265	339	254	364	316	298	221	344	1.00E+04	-
· Mercury (Hg)	0.05	0.24	<0.05	0.08	<0.05	<0.05	<0.05	0.05	<0.05	<0.05	<0.05	0.05	<0.05	<0.05	3.84E+01	-
· Molybdenum (Mo)	1	77	3	33	5	19	2	7	2	2	2	21	12	4	3.26E+03	-
· Nickel (Ni)	1	21	3	22	1	<1	<1	3	<1	2	<1	2	<1	13	1.00E+04	-
· Tin (Sn)	0.5	45.7	5.4	8.2	4.2	7.4	4.3	5.5	4	4.2	2.6	7.6	5.8	6.9	1.00E+04	-
· Zinc (Zn)	1	523	72	387	31	116	31	114	34	92	32	142	162	228	1.00E+04	-
Dioxins and Furans ^(e)
· PCDD/F	Note ^(f)	1.2E-04	-	-	-	6.3E-06	-	8.9E-06	-	-	-	-	-	-	5.00E-03	-
· PCBs	Note ^(f)	9.8E-06	-	-	-	6.1E-07	-	6.4E-07	-	-	-	-	-	-	7.48E-01	-
Notes: (a) LOR = Limit of reporting (b) The duplicate sample taken from S7 (c) The RBRG Industrial values for Total Xylenes (d) The Csat value/limit is the contaminant concentration in soil at which the absorptive limits of the soil particles, the solubility limits of the soil pore water and saturation of soil pore air have been reached (e) Based on the locations and their potential of PCDD/Fs and PCBs contamination, laboratory analysis for PCBs and PCDD/Fs were conducted for three soil samples (S1, S5 & S7). (f) The limits of detection for different PCDD/Fs and PCBs compounds can be referred to the Annex A3.

4.6 Land Contamination Impact Assessment

4.6.1 Conceptual Site Model at the CCPP Site

Based on the above sources identified and the results of the investigation a conceptual site model has been constructed for the Project Site as presented in Table 4.6a (see also Section 3 of the CAR).

Table 4.6a Conceptual Model at the CCPP Site

Source	Pathway	Receptor	Risk
Historical storage of cement and limestone/ foundation construction	Ingestion, inhalation and skin contact	Site workers involved in the decommissioning and demolition work	None – The concentrations in the soil samples were well below the RBRGs. The demolition work will be limited to the top 1.5 m and hence will not touch these materials.
	Soil pore migration	Ground and surface waters	None – The concentrations in the soil samples were well below the RBRGs. The storage occurred over 10 years ago.
MSW feedstock	Ingestion, inhalation and skin contact	Humans (eg Site workers during decommissioning and demolition works)	None – The concentrations in the soil samples were well below the RBRGs. No MSW remains on site at the time of the site visit.
Ash residue from the thermal treatment trial	Ingestion, inhalation and skin contact	Humans (eg Site workers during decommissioning and demolition works)	None – The concentrations in the soil samples were well below the RBRGs. No ash residues were left on the ground at the time of the site visit. The residues currently properly stored within the MRRF building and will be properly utilised or disposed of.
Liquid runoff from MSW/ash	Ingestion, inhalation and skin contacts	Humans (eg Site workers during decommissioning and demolition works)	None – The concentrations in the soil samples were well below the RBRGs.
Liquid runoff from MSW/ash	Soil pore water	Groundwater/ surface water	None – The concentrations in the soil samples were well below the RBRGs. Impermeable hardstanding and enclosed drainage system. No leakage of the wastewater collection UST reported.
Off-site contamination sources	Migration on to the CCPP site via soil pore water or air borne dust	Humans - Site workers during decommissioning Groundwater under the Site	None – The concentrations in the soil samples were well below the RBRGs. There was no evidence to suggest any spillages or leaks have occurred off-site to such an extent as to impact the soils or groundwater underlying the Project Site.

4.6.2 Potential Impacts

It is considered that the only potential receptors at risk might be site workers involved in decommissioning and demolition works, which was discussed in the CAP (see Annex A1).

As the contaminants analysed were either not detected or with concentrations well below the RBRGs, it is not considered that the activities of the CCPP pose risks to any receptor.

No potential land contamination impact is anticipated during the CCPP demolition or thereafter.

4.7 Land Contamination Mitigation Measures

Based on the above investigation results, no mitigation measures are required during the demolition works.

4.8 Residual Environmental Impacts

After completion of demolition works, the Project Site will be backfilled with clean soil and landscaped. The area will be left as an open grassed area whilst awaiting a future industrial use as part of the GICP operation.

There will not be any residual impacts at the Project Site after completion of the demolition works.

4.9 Environmental Monitoring and Audit

Based on the above investigation results, no further investigation is warranted.

As no potential risks to receptors anticipated, no monitoring is deemed necessary.

4.10 Conclusions

The assessment of land contamination sources and the potential impacts to potential receptors were investigated in accordance with the RBRG Guidance. Site appraisal comprising a site visit, and a review of background information and land history in relation to possible land contamination was conducted. Potential sources of contamination and associated impacts, risks or hazards are identified in the CAP (see Annex A1). Land contamination assessment was carried out and results presented in the CAR (see Annex A2).

The results of the site investigation works determined that:

· TPH/BTEX were below the reported detection limits in any of the soil samples collected;

· Concentrations of priority pollutant metals detected were well below the RBRG standards; and

· Levels of PCBs, dioxins and furans analysed in all samples were well below the RBRG values.

Excavation works proposed for the decommissioning and demolition works will be limited to the concrete sub-structures and UST. No soil excavation or groundwater extraction will be required for the Project and hence no off-site disposal of soil and groundwater will be required.

The substructure areas of the Project Site will be filled using clean imported fill materials and rehabilitated as green lawn and open area. The potential for human contact with any underlying contamination in the future is considered low.

As the result of the above, no potential impact from the contaminated soil is anticipated.