TABLE OF CONTENT

7 land contamination. 7-1

7.1 Introduction. 7-1

7.2 Environmental Legislation, Standards and Criteria. 7-1

7.3 Assessment Methodology. 7-1

7.4 Description of the Environment 7-2

7.5 Identification of Potential Land Contamination Concern. 7-3

7.6 Site Investigation Plan. 7-8

7.7 Prediction and Evaluation of Environmental Impacts. 7-13

7.8 Mitigation of Adverse Environmental Impacts. 7-13

7.9 Evaluation of Residual Impacts. 7-14

7.10 Environmental Monitoring and Audit Requirements. 7-14

7.11 Conclusion. 7-15

List of Tables

Table 7.1 Summary of EIA Surveyed Sites within the Proposed HSKEPP Site. 7-2

Table 7.2 Summary of Potential Land Contamination Issues in the Northern Portion of Proposed HSKEPP (SWPTW) 7-6

Table 7.3 Summary of Potential Land Contamination Issues within the Southern Portion of Proposed HSKEPP 7-7

Table 7.4 Sampling and Testing Plan for Decommissioned SWPTW in Northern Portion of Proposed HSKEPP 7-10

Table 7.5 Preliminary Sampling and Testing Plan for Southern Portion of Proposed HSKEPP. 7-12

List of Figures

Figure 7.1	Locations of Identified Potentially Contaminated Sites / Hotspots within the Proposed HSKEPP Site
Figure 7.2	Concerned Areas and Proposed Sampling Locations (Northern Portion of Proposed HSKEPP)

List of Appendices

Appendix 7.1

Contamination Assessment Plan

7 land contamination

7.1 Introduction

7.1.1.1 This section presents the potential land contamination implications associated with the Project.

7.2 Environmental Legislation, Standards and Criteria

7.2.1.1 The relevant environmental legislation guidelines and standards on land contamination aspect include the following:

· Section 3 (Potential Contaminated Land Issues) of Annex 19 “Guidelines for Assessment of Impact on Sites of Cultural Heritage and Other Impacts” of the Technical Memorandum on Environmental Impact Assessment Process (EIAO-TM).

· Guidance Note for Contaminated Land Assessment and Remediation (Guidance Note)

The Guidance Note sets out the requirements for proper assessment and management of potentially contaminated sites such as oil installations (e.g. oil depots, petrol filling stations), gas works, power plants, shipyards / boatyards, chemical manufacturing / processing plants, steel mills / metal workshops, car repairing / dismantling workshops and scrap yards. In addition, this Guidance Note provides guidelines on how site assessments should be conducted and analysed and suggests practical remedial measures that can be adopted for the remediation of contaminated sites.

· Practice Guide for Investigation and Remediation of Contaminated Land (Practice Guide)

This guide outlines typical investigation methods and remediation strategies for the range of potential contaminants typically encountered in Hong Kong.

· Guidance Manual for Use of Risk-based Remediation Goals for Contaminated Land Management (Guidance Manual)

The Guidance Manual introduces the risk-based approach in land contamination assessment and present instructions for comparison of soil and groundwater data to the Risk-Based Remediation Goals (RBRGs) for 54 chemicals of concern (COCs) 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.

7.3 Assessment Methodology

7.3.1.1 Land contamination assessment was previously conducted in the EIA study for Hung Shui Kiu New Development Area (Register No.: AEIAR-203/2016) (HSK NDA EIA Study) under Agreement No. CE 2/2011 (CE) “Hung Shui Kiu New Development Area, Planning and Engineering – Investigation”. The land contamination assessment area in the HSK NDA EIA Study covers the proposed HSKEPP. A Contamination Assessment Plan (HSK NDA EIA CAP) was submitted as part of the HSK NDA EIA study and was approved by EPD in December 2016.

7.3.1.2 Site appraisal, including site walkover and desktop review, was carried out under this EIA study according to the EIAO-TM, Guidance Note, Practice Guide and Guidance Manual. Site walkover was conducted within the proposed HSKEPP site to review the current land uses and to identify any sources of land contamination. For desktop review, the following information was reviewed:

· HSK NDA EIA Study, including the HSK NDA EIA CAP;

· Aerial photographs and topographic maps held by the Lands Department;

· Desk Study Report for Site Investigation and Laboratory Testing under the Project; and

· Records on dangerous goods (DG), chemical wastes, chemical spillage/leakage and fire incidents from the identified potentially contaminated sites from Environmental Protection Department (EPD) and Fire Services Department (FSD).

7.3.1.3 Based on the site appraisal, soil and groundwater sampling and testing at the potentially contaminated areas have been proposed. A Contamination Assessment Plan (CAP), detailed findings of the site appraisal and the proposed site investigation (SI) works, were prepared and enclosed in Appendix 7.1.

7.3.1.4 As reported in the CAP, all the identified concerned areas within the proposed HSKEPP site are currently inaccessible and in operation, the SI works and the subsequent assessment / remediation works are therefore proposed to be carried out in later stage of the Project prior to the commencement of any development or redevelopment works at the concerned areas. For these concerned areas, review of the initial contamination, possible remediation methods, potential insurmountable impacts, SI requirements as well as the tentative timeframe for subsequent submissions were presented in the CAP.

7.4 Description of the Environment

7.4.1.1 The proposed HSKEPP is located in the western part of HSK/HT NDA and covers a total area of approximately 5.2 ha. The proposed HSKEPP is located on a generally flat terrain and is mainly surrounded by Yuen Tau Shan and Kong Sham Western Highway at its southwest side and surrounded by logistics facilities to the north and west. The northern portion of the proposed HSKEPP is currently the decommissioned San Wai Preliminary Treatment Works (SWPTW) and the southern portion is largely occupied by various industrial land uses. The locations of the northern portion (SWPTW) and southern portion of the proposed HSKEPP are shown in Figure 1.1.

7.4.1.2 As mentioned in Section 2, site formation works for the proposed HSKEPP is not under the scope of this Project. The site formation works (including any decontamination works) will be undertaken under the separate HSK NDA project prior to the construction of the proposed HSKEPP.

7.4.1.3 Land contamination assessment was conducted in the HSK NDA EIA Study and the land contamination assessment area in the HSK NDA EIA Study covers the proposed HSKEPP (refer to Figure 1.1 of the CAP enclosed in Appendix 7.1). The assessment comprised of desktop study (e.g. review of aerial photographs, survey maps and relevant information from EPD and FSD) and site surveys.

7.4.1.4 Based on the approved HSK NDA EIA Study, no sites surveyed in the HSK NDA EIA Study (‘EIA Surveyed Sites’) were identified in the northern portion of the proposed HSKEPP. However, the southern portion of the proposed HSKEPP would encroach into 5 EIA Surveyed Sites, 4 of which were considered as potentially contaminated sites. Table 7.1 summarises the details of these EIA Surveyed Sites. The locations of the proposed HSKEPP and the relevant EIA Surveyed Sites are shown in Figure 7.1.

Table 7.1 Summary of EIA Surveyed Sites within the Proposed HSKEPP Site

No.	EIA Surveyed Site ID^(1)	Land Use of EIA Surveyed Site at the time of HSK NDA EIA Study	Partial / Full Encroachment into the Proposed HSKEPP Site	Potentially Contaminated Site?
1	C80a	Warehouse	Partial Encroachment into the Southern Portion of Proposed HSKEPP	Yes
2	C80b	Construction Material Storage and Equipment Depot		Yes
3	C81	Container and Construction Material Storage		Yes
4	C84	Warehouse		TBC^(^2)
5	C85	Vacant		Yes

Note:

(1) Refer to Figure 7.1 for locations of the EIA Surveyed Sites.

(2) The land use of Site C84 was warehouse at the time of the HSK NDA EIA Study with no other historical potentially contaminated land uses identified. A site-reappraisal was recommended at later stage of the development in the HSK NDA EIA Study to confirm whether the site is potentially contaminated and necessity for site investigation works.

7.5 Identification of Potential Land Contamination Concern

7.5.1 General

7.5.1.1 Site appraisal, comprising a review of the relevant findings in the HSK NDA EIA Study, further desktop review and site walkover was carried out in the period from August 2020 to September 2021 for the proposed HSKEPP site. Findings of the site appraisal were detailed in the CAP enclosed in Appendix 7.1 and summarised below.

7.5.2 Review of Historical Land Uses

Review of HSK NDA EIA Study

7.5.2.1 The historical land uses within the proposed HSKEPP site have been reviewed under the HSK NDA EIA Study. The review included series of aerial photographs covering the period from 1978 to 2013. Relevant historical aerial photographs reviewed under the HSK NDA EIA Study are presented in Appendix A of the CAP enclosed in Appendix 7.1.

7.5.2.2 In addition to the above, helicopter reconnaissance and site walkovers were undertaken under the HSK NDA EIA Study in September 2014 and December 2014 respectively to identify the land uses of the surveyed sites at the time. As discussed in Section 7.4 above, no EIA Surveyed Sites were identified within the northern portion of the proposed HSKEPP. According to the relevant historical aerial photographs reviewed, the northern portion of the proposed HSKEPP was occupied by a fish pond from 1978 until 1995 when the SWPTW was developed and no significant land use change was noted since. For the southern portion of the HSKEPP, all of the 5 affected EIA Surveyed Sites were inaccessible at the time as the sites were under private occupation and only peripheral observations were conducted during the site walkovers. Findings of the 5 EIA Surveyed Sites under the HSK NDA EIA Study, including land use history, site observations and photographic records, are presented in Appendix B of the CAP enclosed in Appendix 7.1.

7.5.2.3 Table 7.3 summarised the historical potentially contaminating land uses identified within the EIA Surveyed Sites under the HSK NDA EIA Study.

Further Review under this EIA

7.5.2.4 A review of the latest available aerial photograph after the approval of HSK NDA EIA Study has been undertaken to evaluate the likelihood of potential contamination associated with past land uses within the proposed HSKEPP site. The reviewed aerial photograph is provided in Appendix A of the CAP enclosed in Appendix 7.1.

7.5.2.5 Based on the review of the year 2020 aerial photograph, land use changes (from storage areas / vacant land to warehouse type structures) were noted in EIA Surveyed Site C80b, C81 and C85 within the southern portion of the proposed HSKEPP since the approval of the HSK NDA EIA Study. In addition, an open area storage (Site C85a_2021) was observed which was previously vacant. No significant land use changes were noted within the northern portion and remaining areas of the proposed HSKEPP.

7.5.3 Geology and Hydrogeology

7.5.3.1 Based on the Desk Study Report for Site Investigation and Laboratory Testing of this Project, there is underlain 2m to 5m thick of fill material comprising of typically sand and gravel materials on the ground surface. Occasional 1.5m to 2m pond deposit with clay material is identified in the vicinity of the proposed HSKEPP site. Alluvium deposit comprise of interbedded clay, silt and sand materials with the thickness ranging 1m to 6m, is encountered under the fill stratum. 2m to 7m thick colluvium which comprises of typically silt with some gravel material, is deposited near the natural hillside slope.

7.5.3.2 The proposed HSKEPP site is underlain by diversified rock materials such as siltstone, metasiltstone, tuffaceous siltstone, tuffite, tuff, tuff breccia. The thickness of the saprolite (Grade IV/V material) layer is ranging 25m to 48m in the vicinity of the proposed HSKEPP site, and the rockhead level is varied from -20mPD to -43mPD according to the existing GI records.

7.5.3.3 The available 7-10 days groundwater monitoring records from the existing boreholes indicate that the average groundwater table generally range from 0.5m to 5m below ground level in the proposed HSKEPP site. The highest groundwater is recorded near the hillside on the west of the site.

7.5.4 Records from Government Authorities

Review of HSK NDA EIA Study

7.5.4.1 Based on the findings of the HSK NDA EIA Study, there were no DG license records, reported chemical spillage / leakage incidents or fire incidents within the proposed HSKEPP site. However, there were 4 active chemical waste producer (CWP) records within the proposed HSKEPP site. The relevant records for the proposed HSKEPP site are presented in Table 3.2 of the CAP provided in Appendix 7.1.

Further Review under this EIA

7.5.4.2 The EPD and FSD have been contacted for further records of (i) DG, (ii) CWP(s), (iii) chemicals and chemical wastes spillage / leakage and (iv) reported incidents within the proposed HSKEPP site since the HSK NDA EIA Study.

7.5.4.3 According to the replies given by EPD and FSD, there were no records of spillage / leakage of chemicals / DG reported within the proposed HSKEPP site. In addition, no records of DG licenses or fire incidents were found within the proposed HSKEPP by the FSD.

7.5.4.4 According to the records reviewed, there are 2 valid and 2 invalid CWPs within the proposed HSKEPP site, all of which had been identified in the HSK NDA EIA Study. The relevant details are presented in Table 3.2 of the CAP provided in Appendix 7.1.

7.5.5 Further Site Reconnaissance

7.5.5.1 Site walkovers were conducted under this EIA Study to review the current land uses and to identify any sources of land contamination within the northern portion (SWPTW) and southern portion of the proposed HSKEPP.

Northern Portion of Proposed HSKEPP (SWPTW)

7.5.5.2 Site walkover was conducted on 14 May 2021 within the decommissioned SWPTW. Questionnaire was conducted with available site representative of SWPTW from DSD and the site walkover checklist is attached in Appendix D of the CAP provided in Appendix 7.1.

7.5.5.3 According to the site representative, the SWPTW was decommissioned in March 2021. Currently, the site is largely used for the storage of construction materials. As observed during the site walkover, apart from the transformer house and backup generator, the observed STW facilities were no longer in operation. At the time of the site walkover, storage of construction materials was observed in the open areas in the south and southwest of the site. The remaining areas of the site are covered by access roads and vegetation. Except for the landscaped areas, all external areas including construction materials storage areas and access roads were observed to be paved with intact concrete in good condition and no oil stains / spillage / stressed vegetation were observed during the site walkover. Based on EPD/FSD/DSD records, there were no reported chemical spillage / leakage incidents within the decommissioned SWPTW.

7.5.5.4 Based on the site walkover, there are potential land contamination issues associated with past and current facilities / areas that handled chemicals or petroleum products / chemical wastes. The past and current facilities / areas include the former workshop, the existing chemical storage area in the former solids handling station, the existing backup generator and transformer house. No potentially contaminating land uses / activities were identified in the remaining areas of the decommissioned SWPTW.

7.5.5.5 Details of the site appraisal for the concerned areas identified within SWPTW are summarised in Table 7.2. Findings of the site walkover, including the photographic records and site layout plan, are shown in Appendix C of the CAP provided in Appendix 7.1.

Southern Portion of Proposed HSKEPP Site

7.5.5.6 Site walkover was conducted on 25 August 2021 within the southern portion of the proposed HSKEPP. Similar to the findings of the HSK NDA EIA Study, the southern portion of the proposed HSKEPP site largely consists of potentially contaminated sites (e.g. warehouses and container storage at EIA Surveyed Site C80a, C80b, C81, C84 and C85). An additional potentially contaminated site, an open area storage (Site C85a_2021), was observed. A total of 6 potentially contaminated sites were identified within the southern portion of the proposed HSKEPP. All the sites were private land lots and were inaccessible at the time of site walkover for inspection.

7.5.5.7 Details of the site appraisal for the potentially contaminated sites identified within the southern portion of proposed HSKEPP are summarised in Table 7.3. Findings of the site walkover, including the photographic records and site layout plan, are shown in Appendix C of the CAP provided in Appendix 7.1. The site walkover checklist is presented in Appendix D of the CAP provided in Appendix 7.1.

Table 7.2 Summary of Potential Land Contamination Issues in the Northern Portion of Proposed HSKEPP (SWPTW)

Concerned Facility / Area (Approx. Area)^(1)	Hotspot (Approx. Area)^(1)	Site Observation / Current Potentially Contaminated Land Uses and Activities	Site Walkover Photographic Record Reference in Appendix C of the CAP in Appendix 7.1	Other Historical Potentially Contaminated Land Use / Activities^(2)	Potential COCs^(3)	Future Land Use	Relevant RBRGs Land Use Scenario
Former workshop in administration building (25 m^2)	- Existing chemical storage area (1 m^2) - -Former chemical waste storage area (1 m^2)	· A former workshop was observed within the administration building in the northeast of SWPTW. · The workshop was concrete paved noted to be in good condition with no oil stains / spillage observed. · The workshop has ceased operation since the SWPTW was decommissioned in March 2021. Repair and maintenance for plant equipment on site (e.g. pumps and valves) were reportedly conducted in the workshop when the SWPTW was in operation. · Typical maintenance may have included greasing and lubrication involving lubrication oils. · A signage of ‘chemical waste’ was observed in the former workshop, indicating possible former chemical waste storage. · A few spent lubricating oil drums were observed in the former workshop, which were stored directly on concrete paved floor. According to the site representative from DSD, these chemicals were temporarily stored on site for the current construction works of upgrading the San Wai Sewage Treatment Works (STW) (Phase 1) (adjacent to and north of SWPTW).	Photo 2191, 6848 & 7307 in PR1	-	·Metals (Full List) ·VOCs (Full List) ·SVOCs (Full List) ·PCRs	Effluent polishing Plant	Industrial
Former solids handling station (370 m^2)	Existing chemical storage area (2 m^2)	· The former solids handling station is located in the northwest of the SWPTW and comprised of a control room on the ground floor and a screening press room on the basement floor. The station has ceased operation since the SWPTW was decommissioned in March 2021. All internal floors were generally paved with concrete or tiles in good condition. · Storage of sodium hypochlorite solution (bleach) was observed on wooden pallet in the north of the basement floor. No signs of spillage were observed on the tiled floor in the vicinity of the storage area. As bleach is not considered as a land contaminant, no potential land contamination issues associated with the usage and storage of bleach were anticipated. · 9 lubricating oil / grease drums were observed in the south of the basement floor, which were stored directly on tiled floor. Oil stains were observed on the tiled floor in the vicinity of the chemical storage area. According to the site representative from DSD, these chemicals were temporarily stored on site for the current construction works of upgrading the San Wai STW (Phase 1) (adjacent to and north of SWPTW). · Based on site observation and information provided by the site representative, except for the existing chemical storage area, no other potentially contaminating activities were identified in the former solids handling station.	Photo 6907 in PR1, 2242 & 7345 in PR2	-	·Metals (Full List) ·VOCs (Full List) ·SVOCs (Full List) ·PCRs	Effluent polishing plant	Industrial
Backup generator (15 m^2)	Generator (15 m^2)	· A diesel-powered generator set with a 500L diesel tank was observed in the southeast of SWPTW. · The generator was reportedly used as the backup emergency generator for the site. · The generator was situated directly on intact concrete paved ground with no signs of oil stains / spillage observed in the vicinity.	Photo 7329 in PR1	-	·Metals (Full List) ·VOCs (Full List) ·SVOCs (Full List) ·PCRs	Effluent polishing plant	Industrial
Transformer house (110 m^2)	Transformer*	· The existing transformer house is located in the southeast of SWPTW and is currently operated by CLP and was inaccessible for detailed site inspection. · As reported by the site representative from DSD, the transformer house consists of a switch gear room and a transformer room. · Based on peripheral observations, the transformer house was located on concrete paved ground in good condition with no signs of oil stains / spillage observed in the vicinity.	Photo 6870 in PR1	-	·Metals (Full List) ·VOCs (Full List) ·SVOCs (Full List) ·PCRs ·PCBs	Effluent polishing plant	Industrial

Note:

(1) Refer to Figure 7.1 for locations of the concerned areas.

(2) Based on the findings under the HSK NDA EIA Study. Refer to Appendix A of the CAP in Appendix 7.1 for the relevant historical aerial photographs.

(3) The potential COCs were determined based on Practice Guide.

PCRs – petroleum carbon ranges; VOCs – volatile organic chemicals; SVOCs – semi-volatile organic chemicals and PCBs – polychlorinated biphenyls.

* The location and area of the transformer shall be confirmed when the transformer house was accessible for detailed site inspection.

Table 7.3 Summary of Potential Land Contamination Issues within the Southern Portion of Proposed HSKEPP

Potentially Contaminated Site ID^(1)	Suspected Current Land Use	Approx. Site Area (m^2)	Site Observation / Current Potentially Contaminated Land Uses and Activities	Site Walkover Photographic Record Reference in Appendix C of the CAP in Appendix 7.1	Historical Potentially Contaminated Land Use / Activities ^(2)	Potential COCs^(3)	Partial / Full Encroachment into Proposed HSKEPP Site	Relevant RBRGs Land Use Scenario^(4)
C80a	Warehouse	9,080 (Area encroached into Project: 8,010)	· The site was inaccessible for site inspection. · Large warehouse-type structures and bags of goods on wooden pallets were observed on concrete paved floor from the outside. · Based on EPD information, 1 invalid CWP record registered for waste electrical and electronic equipment recovery was identified for the site. No chemical spillage / DG / incident records were identified for the site.	Photo 8480 in PR3	Container storage, open area storage, recycling facility and warehouse	·Metals (Full List) ·VOCs (Full List) ·SVOCs (Full List) ·PCRs ·PCBs	Partial	Industrial
C80b	Warehouse	17,180 (Area encroached into Project: 16,150)	· The site was inaccessible for site inspection. · A large warehouse and trucks were observed from the outside. The site was largely concrete paved. · Based on EPD information, 1 invalid CWP record registered for construction was identified for the site. No chemical spillage / DG / incident records were identified for the site.	Photo 8484 in PR3	Construction material storage and equipment depot / warehouse	·Metals (Full List) ·VOCs (Full List) ·SVOCs (Full List) ·PCRs	Partial	Industrial
C81	Warehouse and container storage	25,640 (Area encroached into Project: 7,680)	· The site was inaccessible for site inspection. · Large warehouse-type structures, open storage of containers and container handler were observed on concrete paved ground from the outside. · Based on EPD information, 2 valid CWP records registered for machine maintenance and transportation, and 1 invalid CWP records registered for construction were identified for the site. No chemical spillage / DG / incident records were identified for the site.	Photo 8486 & 9429 in PR3	Container and construction material storage / warehouse	·Metals (Full List) ·VOCs (Full List) ·SVOCs (Full List) ·PCRs	Partial	Industrial
C84	Warehouse	1,020 (Area encroached into Project: 860)	· The site was inaccessible for site inspection. · Temporary warehouse-type structures and lorries were observed on concrete paved ground from the outside. · Based on EPD / FSD information, there were no chemical spillage / CWP / DG / incident records for the site.	Photo 7574 & 9384 in PR4	Warehouse	·Metals (Full List) ·VOCs (Full List) ·SVOCs (Full List) ·PCRs	Partial	Industrial
C85	Warehouse	6,000 (Area encroached into Project: 1,070)	· The site was inaccessible for site inspection. · Large temporary warehouse-type structure was observed. · Based on EPD / FSD information, there were no chemical spillage / CWP / DG / incident records for the site.	Photo 7486 & 8496 in PR4	Warehouse	·Metals (Full List) ·VOCs (Full List) ·SVOCs (Full List) ·PCRs	Partial	Lower of Industrial or Public Park
C85a_2021	Open area storage	1,680 (Area encroached into Project: 1,040)	· The site was inaccessible for site inspection. · Pipes and metal sheets were observed on unpaved ground from the outside. · Based on EPD / FSD information, there were no chemical spillage / CWP / DG / incident records for the site.	Photo 7486 & 9391 in PR4	Open area storage	·Metals (Full List) ·VOCs (Full List) ·SVOCs (Full List) ·PCRs	Partial	Lower of Industrial or Public Park

Note:

(1) Refer to Figure 7.1 for locations of the potentially contaminated sites.

(2) Based on the findings under the HSK NDA EIA Study. Refer to Appendix A and B of the CAP in Appendix 7.1 for the relevant aerial photographs and details of the development history for the potentially contaminated land uses / activities.

(3) The potential COCs were determined based on Practice Guide and took in account current and historical land uses, which are subject to change based on site re-appraisal when site access is available.

PCRs – petroleum carbon ranges; VOCs – volatile organic chemicals; SVOCs – semi-volatile organic chemicals and PCBs – polychlorinated biphenyls.

(4) The relevant RBRGs land use scenarios would be subject to findings of the site re-appraisal (refer to Section 7.8.1).

7.5.6 Future Land Uses and Assessment Criteria

7.5.6.1 Land contamination assessment on the potentially contaminated sites would need to be evaluated against the Risk-based Remediation Goals (RBRGs) and if there were presence of non-aqueous phase liquid (NAPL), the soil saturation limit (Csat) and solubility limit, as stipulated in Table 2.1 and Table 2.2 of the Guidance Manual.

7.5.6.2 The RBRGs were developed based on a risk assessment approach to suit the local environmental conditions and community needs in Hong Kong. Decisions on contaminated soil and groundwater remediation are based on the nature and extent of the potential risks that are posed to human receptors as a result of exposure to chemicals in the soil and/or groundwater. RBRGs were developed for four different land use scenarios as below reflecting the typical physical settings in Hong Kong under which people could be exposed to contaminated soil and groundwater. Definitions of the land use scenarios are stipulated in the Guidance Note and Guidance Manual.

· Urban residential

· Rural residential

· Industrial

· Public park

7.5.6.3 As the proposed development under the Project is related to sewage treatment works, the Industrial land use scenario is considered appropriate as the assessment criteria. Nevertheless, as recommended in the HSK NDA CAP, in the event that future land use is revised subsequent to the HSK NDA CAP or in doubt during the assessment, the most stringent set of the RBRGs should be adopted.

7.5.6.4 The future land uses and the appropriate RBRGs land use scenarios are shown in Table 7.2 and Table 7.3

7.6 Site Investigation Plan

7.6.1 Northern Portion of Proposed HSKEPP (SWPTW)

7.6.1.1 Based on the findings of the site appraisal, intrusive SI works is considered necessary for the 4 facilities / areas identified with potential land contamination concerns at the SWPTW in the northern portion of the proposed HSKEPP. A total of 6 sampling locations are proposed to study the vertical profile of possible contamination at the SWPTW. The sampling locations are illustrated in Figure 7.2. However, as the existing transformer house was inaccessible for site walkover at the time of reporting, the proposed sampling location within the transformer house should be reviewed when access is available for site re-appraisal at a later stage of the Project. The key COCs proposed for laboratory analysis included VOCs, SVOCs, metals, PCRs and PCBs. The sampling and testing plan with rationale is presented in Table 7.4.

7.6.1.2 Permission of conducting SI works at the SWPTW could not be obtained from DSD as all the concerned facilities are still in use until demolition of the site. Therefore, it is considered not feasible to conduct the proposed SI works under this EIA study. Given that the transformer house is inaccessible and that the concerned facilities are still in use, site re-appraisal for the entire northern portion of the proposed HSKEPP and SI works should be carried out at a later stage of the Project (refer to Section 7.8.1 for details).

7.6.2 Southern Portion of Proposed HSKEPP

7.6.2.1 Based on the findings of the HSK NDA EIA Study and site appraisal, 6 potentially contaminated sites were identified within the southern portion of the proposed HSKEPP. However, all these concerned sites were inaccessible at the time of reporting to determine the sampling locations for SI works. Given that all of the concerned sites are inaccessible at this stage in time and that re-development of the concerned sites would only commence after a number of years, site re-appraisal should be carried out when site access is available to determine the actual sampling and testing requirements for the concerned sites.

7.6.2.2 A preliminary sampling and testing plan for these potentially contaminated sites has been prepared based on the findings of the HSK NDA EIA Study and site re-appraisal and with reference to EPD’s Practice Guide. Details of the preliminary sampling and testing plan is shown in Table 7.5. Grid sampling strategy, in accordance with Table 2.1 of the Practice Guide and recommendations of the HSK NDA EIA Study, was generally adopted for these potentially contaminated sites. Subject to the findings of site re-appraisal when site access is available, extra sampling locations may be required for any additional potential sources of contamination (or ‘hotspots’) within the concerned sites. The key COCs for the potentially contaminated sites were determined with reference to EPD’s Practice Guide and include VOCs, SVOCs, metals, PCRs, and PCBs.

Table 7.4 Sampling and Testing Plan for Decommissioned SWPTW in Northern Portion of Proposed HSKEPP

Concerned Facility / Area (Approx. Area)	Hotspot (Approx. Area)	Sampling Location ID^(1)	Sampling and Testing Rationale	Sampling Method	Sample Matrix/ Depth^(2)		Parameters to be Tested^(3)
							PCRs	VOCs	SVOCs	Metals	PCBs
Former workshop in administration building (25 m^2)	-	SWENV-BH01	Sampling to target the former workshop (approx. 25 m^2)	Borehole drilling to 2m below the groundwater table or 6m bgl	Soil	(i) 0.5m bgl (ii) 1.5m bgl (iii) 3.0m bgl (iv) at GW level or 6m bgl^(4)	ü	ü	ü	ü	-
					GW	If present^(4)	ü	ü	ü	Mercury only	-
	Existing chemical storage Area (1 m^2)	SWENV-BH02	Target potential hotspot area at chemical storage area (approx. 1 m^2)	Borehole drilling to 2m below the groundwater table or 6m bgl	Soil	(i) 0.5m bgl (ii) 1.5m bgl (iii) 3.0m bgl (iv) at GW level or 6m bgl^(4)	ü	ü	ü	ü	-
					GW	If present^(4)	ü	ü	ü	Mercury only	-
	Former chemical waste storage area (1 m^2)	SWENV-BH03	Target potential hotspot area at former chemical waste storage area (approx. 1 m^2)	Borehole drilling to 2m below the groundwater table or 6m bgl	Soil	(i) 0.5m bgl (ii) 1.5m bgl (iii) 3.0m bgl (iv) at GW level or 6m bgl^(4)	ü	ü	ü	ü	-
					GW	If present^(4)	ü	ü	ü	Mercury only	-
Former solids handling station (370 m^2)	Existing chemical storage area (2 m^2)	SWENV-BH04	Target potential hotspot area at chemical storage area (2 m^2)	Borehole drilling to 2m below the groundwater table or 6m bgl	Soil	(i) 0.5m bgl (ii) 1.5m bgl (iii) 3.0m bgl (iv) at GW level or 6m bgl^(4)	ü	ü	ü	ü	-
					GW	If present^(4)	ü	ü	ü	Mercury only	-
Backup generator	Generator (15 m^2)	SWENV-BH05	Target potential hotspot area at generator (approx. 15 m^2)	Borehole drilling to 2m below the groundwater table or 6m bgl	Soil	(i) 0.5m bgl (ii) 1.5m bgl (iii) 3.0m bgl (iv) at GW level or 6m bgl^(4)	ü	ü	ü	ü	-
					GW	If present^(4)	ü	ü	ü	Mercury only	-
Transformer house (110 m^2)	Transformer^(5)	SWENV-BH06^(5)	Target potential hotspot area (e.g. transformer) at transformer house	Borehole drilling to 2m below the groundwater table or 6m bgl	Soil	(i) 0.5m bgl (ii) 1.5m bgl (iii) 3.0m bgl (iv) at GW level or 6m bgl^(4)	ü	ü	ü	ü	ü
					GW	If present^(4)	ü	ü	ü	Mercury only	ü

Note:

(1) Refer to Figure 7.2 for concerned facility / area and proposed sampling locations.

(2) bgl = below ground level; GW = groundwater

(3) The testing parameters refer to the parameters as shown in Table 2.1 – RBRGs for Soil & Soil Saturation Limit and Table 2.2 – RBRGs for Groundwater and Solubility Limit under VOCs, SVOCs, Metals, PCBs and PCRs in the Guidance Manual.

Since RBRG value of benzo(a)anthracene, benzo(a)pyrene, benzo(g,h,i)perylene, benzo(k)fluoranthene, bis-(2-Ethylhexyl)phthalate, dibenzo(a,h)anthracene, indeno(1,2,3-cd)pyrene and phenol were not available for groundwater, the said parameters would not be tested in groundwater samples.

(4) The deepest depth of sampling should be at groundwater table or 6m bgl, whichever is shallower. Groundwater sample would only be collected if encountered.

(5) The existing transformer house was inaccessible for site walkover at the time of reporting. The potential hotpot area (e.g. transformer) and the proposed sampling location within the transformer house should be reviewed when access is available for site re-appraisal at a later stage of the Project.

Table 7.5 Preliminary Sampling and Testing Plan for Southern Portion of Proposed HSKEPP

Potentially Contaminated Site^(1)	Suspected Current / Historical Potentially Contaminating Land Use ^(2)	Approx. Site Area (m^2)	Approx. Encroached Area (m^2)	Potential COCs^(3)	Recommended Minimum Number of Sampling Locations (Based on Area Within the Proposed HSKEPP Site) ^(4)
C80a	Warehouse / container storage / open area storage / recycling facility	9,080	8,010	Metals (Full List), VOCs (Full List), SVOCs (Full List), PCRs and PCBs	28
C80b	Warehouse / construction material storage / equipment depot	17,180	16,150	Metals (Full List), VOCs (Full List), SVOCs (Full List) and PCRs	29
C81	Warehouse / container storage / construction material storage	25,640	7,680	Metals (Full List), VOCs (Full List), SVOCs (Full List) and PCRs	27
C84	Warehouse	1,020	860	Metals (Full List), VOCs (Full List), SVOCs (Full List) and PCRs	5
C85	Warehouse	6,000	1,070	Metals (Full List), VOCs (Full List), SVOCs (Full List) and PCRs	6
C85a_2021	Open area storage	1,680	1,040	Metals (Full List), VOCs (Full List), SVOCs (Full List) and PCRs	6

Note:

(1) Refer to Figure 7.1 for locations of the identified potentially contaminated sites.

(2) Due to limited site access and only peripheral site inspections were carried out at the time of site walkover and the HSK NDA EIA study, the land use may be subject to change after site re-appraisal when the site is accessible.

(3) The potential COCs are based on findings of the HSK NDA EIA Study and will be confirmed after the site is accessible for re-appraisal.

(i) -Full list refers to the parameters as shown in Table 2.1 – Risk-Based Remediation Goals (RBRGs) for Soil & Soil Saturation Limit and Table 2.2 – RBRGs for Groundwater and Solubility Limit under Volatile Organic Compounds (VOCs), Semi-Volatile Organic Compounds (SVOCs), metals and Petroleum Carbon Ranges (PCRs) in the Guidance Manual for Use of Risk-Based Remediation Goals for Contaminated Land Management.

(ii) - PCBs refer to polychlorinated biphenyls.

(iii) -Since RBRG value for metals except for Mercury, Benzo(a)anthracene, Benzo(a)pyrene, Benzo(g,h,i)perylene, Benzo(k)fluoranthene, bis-(2-Ethylhexyl)phthalate, Dibenzo(a,h)anthracene, Indeno(1,2,3-cd)pyrene and Phenol were not available for groundwater, the said parameters would not be tested in groundwater samples.

(4) The recommended minimum number of sampling locations were based on the area encroached into the proposed HSKEPP site and Table 2.1 of the Practice Guide. For potentially contaminated sites that only partially encroached into the proposed HSKEPP site, the minimum number of sampling locations should be reviewed if the SI works within and outside the proposed HSKEPP site are to be conducted together (e.g. similar to the minimum number of sampling locations recommended in the HSK NDA EIA Study). The actual number of sampling locations will be subject to the findings of the site re-appraisal when the site is accessible.

7.7 Prediction and Evaluation of Environmental Impacts

7.7.1.1 Based on the findings of the HSK NDA EIA Study and the site appraisal under this EIA study, 4 facilities / areas with land contamination concern were identified within the northern portion of HSKEPP (SWPTW) and 6 potentially contaminated sites were identified within the southern portion of proposed HSKEPP.

7.7.1.2 For the northern portion of the proposed HSKEPP (SWPTW), the potential land contamination concerns were associated with handling and storage of chemicals or petroleum products. The sizes of the identified hotspots (ranged from 1 m² to 25 m²) were considered small and all the handling and storage activities of chemicals or petroleum products were carried out on paved concrete floor. For the southern portion of the proposed HSKEPP, it was suspected that the identified potentially contaminated sites are mostly used for storage (e.g. open area storage, container storage, warehouse and construction material storage). The majority of storage sites are usually kept for the storage of goods, whilst only a small portion of the site may be used for potentially contaminating activities such as vehicle / equipment maintenance and the associated chemical handling/storage. In addition, as reported by EPD and FSD, there are no records of spillage / leakage accidents of chemicals / chemical wastes within the proposed HSKEPP. As such, the contamination extent, if any, caused by the operations of the concerned areas is anticipated to be localized. Furthermore, the COCs identified included metals, VOCs, SVOCs, PCRs and PCBs, which are readily treatable using established techniques and have been effectively remediated in Hong Kong using proven remediation techniques.

7.7.1.3 All the concerned areas were inaccessible for detailed site walkover or SI works. In addition, as the proposed HSKEPP site are still in use, there could be change in land use or additional hotspots within the concerned areas or other areas within the proposed HSKEPP site prior to development. Similar to the HSK NDA EIA Study, further works including site re-appraisal for the entire proposed HSKEPP site, SI and if necessary remediation works are recommended to be carried out for the concerned sites prior to the construction of the proposed HSKEPP. Details of the recommended further works are discussed in Section 7.8.1.

7.7.1.4 If the recommended further works were properly implemented, any contaminated soil and groundwater within the proposed YLSEPP site would be properly identified and treated using appropriate remediation methods and according to EPD’s approved Remediation Action Plan (RAP) prior to the construction works. Hence, no potential land contamination impact is anticipated during construction and operation phase of the Project.

7.8 Mitigation of Adverse Environmental Impacts

7.8.1 Recommended Further Works

7.8.1.1 Similar to the HSK NDA EIA Study, the identified concerned areas were inaccessible for detailed site walkover or SI works and were still in operation. In addition, there might be change in land use prior to development which could result in further land contamination issues. Therefore, site re-appraisal should be conducted for the identified concerned areas prior to development of the sites in order to update findings of the site appraisal (e.g. change in land use and additional hotspots) and the sampling and testing requirements for SI works. In addition, re-appraisal would be required for the other remaining areas of the proposed HSKEPP site in order to assess the latest land uses and site conditions. Supplementary CAP(s), incorporating findings of the site re-appraisal for the entire proposed HSKEPP site and the updated sampling and testing strategy, should be prepared and submitted to EPD for approval prior to conducting any SI works.

7.8.1.2 SI works should then be carried out according to the EPD approved supplementary CAP(s). After completion of the SI works, CAR(s) should be prepared to present findings of the SI works. If contamination has been identified, RAP(s) should be prepared to recommend specific remediation measures and submitted to EPD for approval. Any contaminated soil and groundwater should be treated according to the EPD approved RAP(s) and Remediation Report(s) (RR(s)) would also be prepared to demonstrate that the clean-up works are adequate and should be submitted to EPD for approval after completion of the remediation works. No development works shall be commenced prior to EPD’s agreement of the RR.

7.8.2 Possible Remediation Measures

7.8.2.1 According to the Practice Guide, the need to remediate the contaminated areas and the nature, level and extent of contamination would be determined based on the findings of the SI works to be presented in the CAR(s). The appropriate remediation methods should be selected based on the findings of the SI works and would be presented in the RAP(s). The possible remediation methods are detailed in Section 5.2 of the CAP provided in Appendix 7.1.

7.8.3 Mitigation Measures for Remediation Works

7.8.3.1 Mitigation measures for the remediation works would depend on the nature / extent of contamination and the method of treatment. The mitigation measures will be recommended in the RAP and would typically include the following:

· Excavation profiles must be properly designed and executed with attention to the relevant requirements for environment, health and safety;

· Excavation shall be carried out during dry season as far as possible to minimise contaminated runoff from contaminated soils;

· Supply of suitable clean backfill material (or treated soil) after excavation;

· Stockpiling site(s) shall be lined with impermeable sheeting and bunded. Stockpiles shall be fully covered by impermeable sheeting to reduce dust emission. If this is not practicable due to frequent usage, regular watering shall be applied. However, watering shall be avoided on stockpiles of contaminated soil to minimise contaminated runoff.

· Vehicles containing any excavated materials shall be suitably covered to limit potential dust emissions or contaminated wastewater run-off, and truck bodies and tailgates shall be sealed to prevent any discharge during transport or during wet conditions;

· Speed control for the trucks carrying contaminated materials shall be enforced;

· Vehicle wheel and body washing facilities at the site’s exist points shall be established and used; and

· Pollution control measures for air emissions (e.g. from biopile blower and handling of cement), noise emissions (e.g. from blower or earthmoving equipment), and water discharges (e.g. runoff control from treatment facility) shall be implemented and complied with relevant regulations and guidelines.

7.9 Evaluation of Residual Impacts

7.9.1.1 Land contamination issue within the concerned areas are considered surmountable if the recommended actions as outlined in Section 7.8.1 were carried out. Any contaminated soil and groundwater would be identified and properly treated using appropriate remediation methods and according to the EPD approved RAP prior to development of the concerned areas. No residual land contamination impacts are expected.

7.10 Environmental Monitoring and Audit Requirements

7.10.1.1 Remediation works, if necessary, would be carried out based on the recommended further works outlined in Section 7.8.1. Mitigation measures as recommended in the future EPD approved RAP should be implemented during the remediation works. The Environmental Monitoring and Audit (EM&A) requirements should be carried out in the form of regular site inspection to ensure the recommended mitigation measures are properly implemented.

7.11 Conclusion

7.11.1.1 A site appraisal, including the review of the HSK NDA EIA Study, desktop review and site walkover, was conducted from August 2020 to September 2021 to identify any potentially contaminating land uses within the proposed HSKEPP site. Based on the site appraisal findings, 4 facilities / areas with land contamination concern within the northern portion of HSKEPP (SWPTW) and 6 potentially contaminated sites within the southern portion of HSKEPP were identified.

7.11.1.2 Similar to the HSK NDA EIA Study, the identified concerned areas were inaccessible for detailed site walkover or SI works and still in operation. In addition, there might be change in land use prior to development which could result in further land contamination issues. Therefore, site re-appraisal should be conducted for the identified concerned areas prior to development of the sites in order to update findings of the site appraisal (e.g. locations of hotspots) and the sampling and testing requirements for SI works. In addition, re-appraisal would be required for the other remaining areas of the proposed HSKEPP site in order to assess the latest land uses and site conditions. The further works including site re-appraisal for the whole proposed HSKEPP site, associated SI works, any necessary remediation works and submission of supplementary CAP / CAR / RAP / RR are recommended to be carried out prior to commencement of any construction or development works, and would follow the relevant Guidance Manual, Guidance Note and Practice Guide.

7.11.1.3 With the implementation of the recommended further works for the Project, any soil / groundwater contamination associated with past or present contaminating land uses would be identified and properly treated prior to the construction works. No insurmountable land contamination impacts to the Project are therefore anticipated.