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. 7-9

7.7           Prediction and Evaluation of Environmental Impacts. 7-14

7.8           Mitigation of Adverse Environmental Impacts. 7-14

7.9           Evaluation of Residual Impacts. 7-15

7.10         Environmental Monitoring and Audit Requirements. 7-15

7.11         Conclusion. 7-15

 

List of Tables

 

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

Table 7.2              Summary of Potential Land Contamination Issues within the Proposed YLSEPP Site  7-5

Table 7.3              Preliminary Sampling and Testing Plan. 7-11

 

List of Figures

 

Figure 7.1

Location Plan of YLSEPP and Relevant EIA Surveyed Sites

 

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 Housing Sites in Yuen Long South (Register No.: AEIAR-215/2017) (YLS EIA Study) under Agreement No. CE 35/2012 (CE) “Planning and Engineering Study for Housing Sites in Yuen Long South – Investigation”.  The scope of works covered under the YLS EIA study included site formation and, if necessary, decontamination works for the proposed YLSEPP site.  A Contamination Assessment Plan (YLS EIA CAP) was submitted as part of the YLS EIA Study and the YLS EIA Study was approved by EPD in November 2017.  

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 YLSEPP site to review the current land uses and to identify any sources of land contamination.  For desktop review, the following information was reviewed:

·         YLS EIA Study, including the YLS EIA CAP;

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

·         Available records on dangerous goods, chemical wastes, chemical spillage/leakage and fire incidents 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 sites 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 potentially contaminated sites within the proposed YLSEPP site are currently inaccessible and in operation.  The SI works and the subsequent assessment / remediation works are therefore proposed to be carried out when site access is available (e.g. after land resumption) but prior to commencement of any construction or development works at the identified contaminated sites.  For these identified potentially contaminated sites, review of the initial contamination, possible remediation methods, potential insurmountable impacts, SI requirements as well as the tentative timeframe for further works were presented in the CAP.

7.4                  Description of the Environment

7.4.1.1           The proposed YLSEPP is located in the southern end of Yuen Long South Development Area (YLS DA) and covers a total area of approximately 4.6 ha.  The proposed YLSEPP is located on a generally flat terrain and is mainly surrounded by various industrial land uses to the north, east and west, along with roads and nullah to the east and vegetated land to the west and south. The location of the Project is shown in Figure 1.1.

7.4.1.2           As mentioned in Section 2, site formation works for the proposed YLSEPP is not under the scope of this Project.  The site formation works (including any decontamination works) will be undertaken by CEDD separately under the YLS DA project prior to the construction of the proposed YLSEPP.

7.4.1.3           Land contamination assessment was conducted in the YLS EIA Study and the land contamination assessment area in the YLS EIA Study covers the proposed YLSEPP (refer to Figure 1.1). 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 YLS EIA Study, the proposed YLSEPP would encroach into 23 sites surveyed in the YLS EIA Study (the ‘EIA Surveyed Sites’), all of which were considered as potentially contaminated sites (i.e. sites categorised as “Yes contamination rating”).  Table 7.1 summarises the details of these EIA Surveyed Sites. The locations of the proposed YLSEPP and the relevant EIA Surveyed Sites are shown in Figure 7.1.

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

No.

EIA Surveyed Site ID(1)

Land Use of EIA Surveyed Site at the time of YLS EIA Study

Partial / Full Encroachment into Proposed YLSEPP Site

1

E379

Warehouse

Partial

2

E396

Warehouse

Partial

3

E397

Open area storage

Partial

4

E399

Open area storage

Partial

5

E400

Warehouse

Partial

6

E401

Warehouse

Full

7

E402

Warehouse

Full

8

E402a

Warehouse

Full

9

E403

Warehouse

Full

10

E404

Open area storage

Full

11

E405

Warehouse

Partial

12

E406

Construction equipment storage

Full

13

E407

Metal workshop

Partial

14

E408

Warehouse

Partial

15

E408a

Warehouse

Full

16

E409

Warehouse

Partial

17

E410m

Open area storage

Full

18

E412

Warehouse

Full

19

E413

Warehouse

Partial

20

E414

Warehouse

Partial

21

E415

Warehouse

Partial

22

E425

Warehouse

Partial

23

E486

Warehouse

Partial

                          Note:

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

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 of the YLS EIA Study, further desktop review and site walkover was carried out in the period from August 2020 to May 2021 for the proposed YLSEPP 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 YLS EIA Study

7.5.2.1           The historical land uses of the EIA Surveyed Sites have been reviewed under the YLS EIA Study.  The review included series of aerial photographs covering the period from 1963 to 2012. Relevant historical aerial photographs of the 23 EIA Surveyed Sites in Table 7.1 are presented in Appendix A of the CAP enclosed in Appendix 7.1.

7.5.2.2           In addition to the above, site walkovers were carried out under the YLS EIA Study from March 2013 to April 2014 to identify the land uses of the surveyed sites at the time.  All of the 23 EIA Surveyed Sites affected by the Project were inaccessible at the time and only peripheral observations were conducted during the site walkover. Findings of the 23 EIA Surveyed Sites under the YLS EIA Study, including land use history, site walkover observation and photographic records, are presented in Appendix B of the CAP enclosed in Appendix 7.1.

7.5.2.3           Table 7.2 summarised the potentially contaminating land uses identified within the EIA Surveyed Site under the YLS EIA Study.

Further Review under this EIA

7.5.2.4           A review of the latest available aerial photograph after the approval of YLS EIA Study has been undertaken to evaluate the likelihood of potential contamination associated with past land uses within the proposed YLSEPP 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, no significant land use changes were noted within the proposed YLSEPP site since the approval of the YLS EIA Study. Most of the proposed YLSEPP site remained occupied by industrial activities.

7.5.3              Geology and Hydrogeology

7.5.3.1           Based on the YLS EIA Study, the proposed YLSEPP is located within an area of relatively complex geology. The district of Yuen Long is situated in a structurally complex Palaeozoic sedimentary basin surrounded by Mesozoic granitic and volcanic rocks, with an extensive amount of faulting and folding. The rocks originally deposited within the sedimentary basin have been heavily metamorphosed, leading to the formation of marble. The younger volcanic rocks of the Tsuen Wan Volcanic group overlay the marble bearing Palaeozoic rocks. Both the sedimentary and volcanic rocks have subsequently been intruded by granite. 

7.5.3.2           The proposed YLSEPP is located almost exclusively on the low-lying Yuen Long Plain, an ancient alluvial flood plain, and is bound to the south and southeast by mountainous terrain. The superficial deposits anticipated within the proposed YLSEPP site are largely expected to comprise alluvium and colluvium. The colluvium deposits occur upslope of the alluvial plains, filling the floors of incised valleys, but are also found beneath alluvial deposits, mainly filling irregularities in the karst marble surface. The alluvium was deposited under various conditions, ranging from periods of active erosion leading to the deposition of coarser grained materials, to quieter periods allowing far-travelled silts and clays to be deposited. Contours in the local area suggest the paleogeography of meandering channels, with some pools of standing water leading to the deposition of lacustrine type deposits.

7.5.4              Records from Government Authorities

Review of YLS EIA Study

7.5.4.1           Based on the findings of the YLS EIA Study, there were no dangerous goods (DG) license / chemical waste producer (CWP) records, reported chemical spillage / leakage incidents or fire incidents within the proposed YLSEPP site.

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 YLSEPP site since the YLS 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 YLSEPP site. In addition, no records of DG licenses or fire incidents were found within the proposed YLSEPP by the FSD.

7.5.4.4           There are 4 CWP records identified within the proposed YLSEPP site. 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 walkover was conducted on 4 May 2021 under this EIA study to review the current land uses and to identify any sources of land contamination within the proposed YLSEPP site.  Similar to the findings of the YLS EIA CAP, the proposed YLSEPP site consisted of potentially contaminated sites (e.g. warehouses, open area storages and workshop).  However, all the sites were private land lots and were inaccessible at the time of site walkover for inspection.

7.5.5.2           Findings of the site walkover for the potentially contaminated sites are summarized in Table 7.2. Photographic records taken during the site walkover are presented in Appendix C of the CAP enclosed in Appendix 7.1.

Table 7.2          Summary of Potential Land Contamination Issues within the Proposed YLSEPP Site

Potentially Contaminated Site ID(1)

Current Land Use

Approx. Site Area (m2)

Site Observation / Current Potentially Contaminated Land Uses and Activities

Site Walkover Photographic Record Reference in Appendix C

Suspected Historical Potentially Contaminated Land Use / Activities (2)

Potential COCs(3)

Partial / Full Encroachment into Proposed YLSEPP Site

Relevant RBRGs Land Use Scenario(4)

E379

Unknown

1,620

(Area Encroached into Project: 10)

·      The site was inaccessible for site inspection.

·      Gate closed. Large temporary structures observed.

·      Based on EPD / FSD information, there were no chemical spillage / CWP / DG / incident records for the site.

 

Photo 7145 in PR1

Warehouse

·Metals (Full List)

·VOCs (Full List)

·SVOCs (Full List)

·PCRs

Partial

Industrial or other RBRGs based on the future land use outside the proposed YLSEPP site.

E396

Unknown

1,510

(Area Encroached into Project: 220)

·      The site was inaccessible for site inspection.

·      Gate closed. Large temporary structure with oil drums observed from the outside.

·      Based on EPD / FSD information, there were no chemical spillage / CWP / DG / incident records for the site.

 

Photo 1770 in PR3

Warehouse

·Metals (Full List)

·VOCs (Full List)

·SVOCs (Full List)

·PCRs

Partial

Industrial or other RBRGs based on the future land use outside the proposed YLSEPP site.

E397

Unknown

2,420

(Area Encroached into Project: 1,340)

·      The site consists of concrete paved access road and temporary structures.

·      Limited site access. Gates closed. Oil drum and forklift observed outside the temporary structures.

·      Based on EPD / FSD information, there were no chemical spillage / CWP / DG / incident records for the site.

 

Photo 1757, 1761 & 7231 in PR3

Open area storage

·Metals (Full List)

·VOCs (Full List)

·SVOCs (Full List)

·PCRs

Partial

Industrial or other RBRGs based on the future land use outside the proposed YLSEPP site.

E399

Unknown

880

(Area Encroached into Project:780)

·      The site consists of concrete paved access road and temporary structures.

·      Limited site access. Gates closed.

·      Based on EPD / FSD information, there were no chemical spillage / CWP / DG / incident records for the site.

 

Photo 1755 & 7140 in PR2

Open area storage

·Metals (Full List)

·VOCs (Full List)

·SVOCs (Full List)

·PCRs

Partial

Industrial or other RBRGs based on the future land use outside the proposed YLSEPP site.

E400

Unknown

430

(Area Encroached into Project: 250)

·      The site was inaccessible for site inspection.

·      Gates closed. Temporary structure observed behind closed gate.

·      Based on EPD / FSD information, there were no chemical spillage / CWP / DG / incident records for the site.

 

Photo 6598 in PR2

Warehouse / open area storage

·Metals (Full List)

·VOCs (Full List)

·SVOCs (Full List)

·PCRs

Partial

Industrial or other RBRGs based on the future land use outside the proposed YLSEPP site.

E401

Suspected warehouse

1,100

·      The site was inaccessible for site inspection.

·      Parked vehicles, metal carts, wooden pallets and parcels observed on concrete paved ground within large temporary structures.

·      Based on EPD / FSD information, there were no chemical spillage / CWP / DG / incident records for the site.

 

Photo 1666 in PR2

Warehouse / open area storage

·Metals (Full List)

·VOCs (Full List)

·SVOCs (Full List)

·PCRs

Full

Industrial

E402

Suspected warehouse

500

·      The site was inaccessible for site inspection.

·      Gate closed. Large temporary structures observed behind closed gate.

·      Based on EPD information, 1 invalid CWP record registered for import and export of industrial tires was identified for the site. No chemical spillage / DG / incident records were identified for the site.

 

Photo 1662 in PR2

Warehouse / open area storage

·Metals (Full List)

·VOCs (Full List)

·SVOCs (Full List)

·PCRs

Full

Industrial

E402a

Suspected warehouse

330

·      The site was inaccessible for site inspection.

·      Gate closed. Large temporary structures observed behind closed gate.

·      Based on EPD information, 1 invalid CWP record registered for import and export of industrial tires was identified for the site. No chemical spillage / DG / incident records were identified for the site.

 

Photo 1664 in PR2

Warehouse / open area storage

·Metals (Full List)

·VOCs (Full List)

·SVOCs (Full List)

·PCRs

Full

Industrial

E403

Suspected warehouse / waste recycling workshop

570

·      The site was inaccessible for site inspection.

·      Gate closed. Large temporary structure observed behind closed gate.

·      Based on EPD information, 1 valid CWP record registered for recycling and wholesales of electronic and metal products was identified for the site. No chemical spillage / DG / incident records were identified for the site.

 

Photo 7121 in PR2

Warehouse

·Metals (Full List)

·VOCs (Full List)

·SVOCs (Full List)

·PCRs

·PCBs

Full

Industrial

E404

Suspected waste recycling workshop

990

·      The site was inaccessible for site inspection.

·      Gate closed. A sign of metal recycling on the closed gate.

·      Based on EPD information, 1 valid CWP record registered for recycling and wholesales of electronic and metal products was identified for the site. No chemical spillage / DG / incident records were identified for the site.

 

Photo 6520 in PR4

Open area storage

·Metals (Full List)

·VOCs (Full List)

·SVOCs (Full List)

·PCRs

·PCBs

Full

Industrial

E405

Suspected warehouse

6,370

(Area Encroached into Project: 5,800)

·      The site was inaccessible for site inspection.

·      A large warehouse and container trucks on concrete paved ground were observed from the outside.

·      Based on EPD / FSD information, there were no chemical spillage / CWP / DG / incident records for the site.

 

Photo 7111 in PR5

Warehouse / open area storage

·Metals (Full List)

·VOCs (Full List)

·SVOCs (Full List)

·PCRs

Partial

Industrial or other RBRGs based on the future land use outside the proposed YLSEPP site.

E406

Suspected construction materials storage

2,380

·      The site was inaccessible for site inspection.

·      Large temporary structures, an operating crane truck with storage of construction materials e.g. iron bars and bricks were observed from the outside.

·      Based on EPD / FSD information, there were no chemical spillage / CWP / DG / incident records for the site.

 

Photo 1642 & 7096 in PR5

Construction equipment storage / open area storage

·Metals (Full List)

·VOCs (Full List)

·SVOCs (Full List)

·PCRs

Full

Industrial

E407

Suspected metal workshop

3,320

(Area Encroached into Project:3,260)

·      The site was inaccessible for site inspection.

·      One of the gates was opened. Large temporary structures, parked vehicles and heavy machineries with storage of metal bars observed.

·      Based on EPD / FSD information, there were no chemical spillage / CWP / DG / incident records for the site.

 

Photo 1626, 1627 & 1634 in PR5

Metal workshop / open area storage

·Metals (Full List)

·VOCs (Full List)

·SVOCs (Full List)

·PCRs

Partial

Lower of Industrial or Public Park or other RBRGs based on the future land use outside the proposed YLSEPP site.

E408

Suspected warehouse

2,770

(Area Encroached into Project: 2,730)

·      The site was inaccessible for site inspection.

·      Large temporary structures, metal carts and wooden pallets observed.

·      Based on EPD / FSD information, there were no chemical spillage / CWP / DG / incident records for the site.

 

Photo 6535 in PR4

Warehouse / open area storage

·Metals (Full List)

·VOCs (Full List)

·SVOCs (Full List)

PCRs

Partial

Lower of Industrial or Public Park or other RBRGs based on the future land use outside the proposed YLSEPP site.

E408a

Suspected warehouse

310

·      The site was inaccessible for site inspection.

·      Gates closed. Large temporary structures observed behind closed gates.

·      Based on EPD / FSD information, there were no chemical spillage / CWP / DG / incident records for the site.

 

Photo 1735 & 6715 in PR4

Warehouse / open area storage

·Metals (Full List)

·VOCs (Full List)

·SVOCs (Full List)

PCRs

Full

Industrial

E409

Suspected warehouse

450

(Area Encroached into Project: 440)

·      The site was inaccessible for site inspection.

·      Gate closed. Large temporary structure observed.

·      Based on EPD / FSD information, there were no chemical spillage / CWP / DG / incident records for the site.

 

Photo 1744 in PR4

Warehouse / open area storage

·Metals (Full List)

·VOCs (Full List)

·SVOCs (Full List)

·PCRs

Partial

Lower of Industrial or Public Park or other RBRGs based on the future land use outside the proposed YLSEPP site.

E410m

Suspected open area storage

3,190

·      The site was inaccessible for site inspection.

·      Limited site access. Gate closed. Storage of construction equipment / machineries were observed behind closed gate.

·      A truck on unpaved open area / access road was observed adjacent to the storage area.

·      Based on EPD / FSD information, there were no chemical spillage / CWP / DG / incident records for the site.

 

Photo 1660, 1741 & 6543 in PR3

Open area storage

·Metals (Full List)

·VOCs (Full List)

·SVOCs (Full List)

·PCRs

Full

Industrial

E412

Suspected warehouse

2,340

·      The site was inaccessible for site inspection.

·      Large temporary structures with pallets, forklift, metal carts and trucks observed. The site was largely paved. 

·      Based on EPD / FSD information, there were no chemical spillage / CWP / DG / incident records for the site.

 

Photo 1698 in PR1

Warehouse / open area storage

·Metals (Full List)

·VOCs (Full List)

·SVOCs (Full List)

·PCRs

Full

Industrial

E413

Suspected warehouse

8,860

(Area Encroached into Project: 910)

·      The site was inaccessible for site inspection.

·      A large warehouse with storage of goods observed. Trucks and vehicles were parked on concrete paved ground outside the warehouse.

·      Based on EPD / FSD information, there were no chemical spillage / CWP / DG / incident records for the site.

 

Photo 6712 in PR1

Warehouse / open area storage

·Metals (Full List)

·VOCs (Full List)

·SVOCs (Full List)

·PCRs

Partial

Lower of Industrial or Public Park or other RBRGs based on the future land use outside the proposed YLSEPP site.

E414

Suspected warehouse

2,350

(Area Encroached into Project: 1,000)

·      The site was inaccessible for site inspection.

·      Large temporary structures, trucks, metal carts and wooden pallets were observed from the outside. The site was largely paved.

·      Based on EPD information, 1 invalid CWP record registered for recycling of electronic and metal products was identified for the site. No chemical spillage / DG / incident records were identified for the site.

 

Photo 1703 in PR1

Warehouse / open area storage

·Metals (Full List)

·VOCs (Full List)

·SVOCs (Full List)

·PCRs

Partial

Industrial or other RBRGs based on the future land use outside the proposed YLSEPP site.

E415

Suspected warehouse

730

(Area Encroached into Project: 230)

·      The site was inaccessible for site inspection.

·      A large warehouse with storage of goods, a truck and an excavator were observed from the outside.

·      Based on EPD / FSD information, there were no chemical spillage / CWP / DG / incident records for the site.

 

Photo 6625 in PR1

Warehouse / open area storage

·Metals (Full List)

·VOCs (Full List)

·SVOCs (Full List)

·PCRs

Partial

Lower of Industrial or Public Park or other RBRGs based on the future land use outside the proposed YLSEPP site.

E425

Suspected warehouse

940

(Area Encroached into Project: 510)

·      The site was inaccessible for site inspection.

·      Gate closed. Temporary structure observed.

·      Based on EPD / FSD information, there were no chemical spillage / CWP / DG / incident records for the site.

 

Photo 6441 in PR6

Warehouse / open area storage

·Metals (Full List)

·VOCs (Full List)

·SVOCs (Full List)

·PCRs

Partial

Lower of Industrial or Public Park or other RBRGs based on the future land use outside the proposed YLSEPP site.

E486

Suspected warehouse

8,910

(Area Encroached into Project: 7,810)

·      The site was inaccessible for site inspection.

·      Temporary structures, containers, generator and trucks observed.

·      Based on EPD information, 1 invalid CWP record registered for construction equipment service was identified for the site. No chemical spillage / DG / incident records were identified for the site.

 

Photo 1574, 6441 & 7042 in PR6

Warehouse / open area storage

·Metals (Full List)

·VOCs (Full List)

·SVOCs (Full List)

·PCRs

Partial

Lower of Industrial or Public Park or other RBRGs based on the future land use outside the proposed YLSEPP site.

Note:

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

(2) Based on the findings under the YLS EIA Study.  Refer to Appendix B of the CAP in Appendix 7.1 for details of the development history for the potentially contaminated land uses / activities.

(3) The potential Chemicals of Concern (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 (refer to Section 7.8.1).

      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 YLS EIA Study, where a site would be developed into more than one land uses (e.g. EIA Surveyed Sites that only partially encroached into the proposed YLSEPP site), the most stringent set of the RBRGs should be adopted.  In this regard, for the partially encroached EIA Surveyed Sites, the appropriate RBRGs land use scenario should be confirmed at the time of site re-appraisal (refer to Section 7.8.1) based on the final future land uses within the site that is outside of the proposed YLSEPP.  In any case, if there is doubt to the future land uses during the site re-appraisal, the most stringent set of RBRGs should be adopted as the clean-up standard.

7.5.6.4           In addition to the above, as recommended in the YLS EIA Study, if the remediated soils are required to be excavated during the construction stage and re-used off-site, the most stringent set of RBRGs should be adopted to ensure the remediated soil could be re-used in any situation.

7.5.6.5           The future land uses and the appropriate RBRGs land use scenarios are shown in Table 7.2.

7.6                  Site Investigation Plan

7.6.1.1           Based on the findings of the YLS EIA Study and site appraisal, 23 potentially contaminated sites were identified within the proposed YLSEPP site.  However all of these concerned sites remained 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 after land resumption, site re-appraisal should be carried out when site access is available to determine the actual sampling and testing requirements for the concerned sites.

7.6.1.2           A preliminary sampling and testing plan for these potentially contaminated sites has been prepared based on the findings of the YLS EIA Report and site appraisal and with reference to EPD’s Practice Guide.  Details of the preliminary sampling and testing plan is shown in Table 7.3.  Grid sampling strategy, in accordance with Table 2.1 of the Practice Guide and recommendations of the YLS EIA Study, was generally adopted.  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 chemicals of concern (COCs) for the potentially contaminated sites were determined with reference to EPD’s Practice Guide and include metals, volatile organic compounds (VOCs), semi-volatile organic compounds (SVOCs), petroleum carbon ranges (PCRs) and polychlorinated biphenyls (PCBs).

Table 7.3          Preliminary Sampling and Testing Plan

Potentially Contaminated Site (1)

Suspected Current / Historical Potentially Contaminating Land Use (2)

Approx. Site Area (m2)

Approx. Encroached Area (m2)

Potential COCs(3)

Recommended Minimum Number of Sampling Locations (Based on Area Within the Proposed YLSEPP Site)(4)

E379

Warehouse

1,620

10

Metals (Full List), VOCs (Full List), SVOCs (Full List) and PCRs

1

E396

Warehouse

1,510

220

Metals (Full List), VOCs (Full List), SVOCs (Full List) and PCRs

3

E397

Open area storage

2,420

1,340

Metals (Full List), VOCs (Full List), SVOCs (Full List) and PCRs

8

E399

Open area storage

880

780

Metals (Full List), VOCs (Full List), SVOCs (Full List) and PCRs

5

E400

Warehouse / open area storage

430

250

Metals (Full List), VOCs (Full List), SVOCs (Full List) and PCRs

3

E401

Warehouse / open area storage

1,100

1,100

Metals (Full List), VOCs (Full List), SVOCs (Full List) and PCRs

7

E402

Warehouse / open area storage

500

500

Metals (Full List), VOCs (Full List), SVOCs (Full List) and PCRs

3

E402a

Warehouse / open area storage

330

330

Metals (Full List), VOCs (Full List), SVOCs (Full List) and PCRs

3

E403

Warehouse / waste recycling workshop

570

570

Metals (Full List), VOCs (Full List), SVOCs (Full List), PCRs and PCBs

3

E404

Waste recycling workshop / open area storage

990

990

Metals (Full List), VOCs (Full List), SVOCs (Full List), PCRs and PCBs

6

E405

Warehouse / open area storage

6,370

5,800

Metals (Full List), VOCs (Full List), SVOCs (Full List) and PCRs

20

E406

Construction materials storage / construction equipment storage / open area storage

2,380

2,380

Metals (Full List), VOCs (Full List), SVOCs (Full List) and PCRs

12

E407

Metal workshop / open area storage

3,320

3,260

Metals (Full List), VOCs (Full List), SVOCs (Full List) and PCRs

13

E408

Warehouse / open area storage

2,770

2,730

Metals (Full List), VOCs (Full List), SVOCs (Full List) and PCRs

13

E408a

Warehouse / open area storage

310

310

Metals (Full List), VOCs (Full List), SVOCs (Full List) and PCRs

3

E409

Warehouse / open area storage

450

440

Metals (Full List), VOCs (Full List), SVOCs (Full List) and PCRs

3

E410m

Open area storage

3,190

3,190

Metals (Full List), VOCs (Full List), SVOCs (Full List) and PCRs

13

E412

Warehouse / open area storage

2,340

2,340

Metals (Full List), VOCs (Full List), SVOCs (Full List) and PCRs

12

E413

Warehouse / open area storage

8,860

910

Metals (Full List), VOCs (Full List), SVOCs (Full List) and PCRs

5

E414

Warehouse / open area storage

2,350

1,000

Metals (Full List), VOCs (Full List), SVOCs (Full List) and PCRs

6

E415

Warehouse / open area storage

730

230

Metals (Full List), VOCs (Full List), SVOCs (Full List) and PCRs

3

E425

Warehouse / open area storage

940

510

Metals (Full List), VOCs (Full List), SVOCs (Full List) and PCRs

3

E486

Warehouse / open area storage

8,910

7,810

Metals (Full List), VOCs (Full List), SVOCs (Full List) and PCRs

27

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 YLS EIA study, the land use may be subject to change after site re-appraisal when the site is accessible.

(3)     The potential chemicals of concern (COCs) are based on findings of the YLS EIA report 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 YLSEPP site and Table 2.1 of the Practice Guide.  For potentially contaminated sites that only partially encroached into the proposed YLSEPP site, the minimum number of sampling locations should be reviewed if the SI works within and outside the proposed YLSEPP site are to be conducted together (e.g. similar to the minimum number of sampling locations recommended in the YLS 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 YLS EIA Study and the site appraisal under this EIA study, of the 23 identified potentially contaminated sites, 21 (or 91% of the potentially contaminated sites) have been used as storage or warehouse.  The majority of these sites are usually kept for the storage of goods, whilst only a small portion of the site is reserved for chemical storage.  As such, the contamination extent, if any, caused by the operations of the identified potentially contaminated sites is anticipated to be localised.  Furthermore, the COCs identified included metals, VOCs, SVOCs, PCRs and PCBs, which are readily treatable using established techniques and these COCs have been effectively remediated in Hong Kong using proven remediation techniques.

7.7.1.2           Given the above and similar to the findings of the YLS EIA Study, the land contamination problems in the identified potentially contaminated sites would not be considered as insurmountable.

7.7.1.3           The potentially contaminated sites were inaccessible for detailed site walkover or SI works.  In addition, as the sites were still in operation, it was considered not suitable to carry out the SI works as there could be change in land use prior to development for both the potentially contaminated sites and other areas within the proposed YLSEPP site.  Similar to the YLS EIA Study, further works including site re-appraisal for the entire proposed YLSEPP site, SI and if necessary remediation works are recommended to be carried out for the concerned sites prior to the construction of the proposed YLSEPP. 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 recommendation in the YLS EIA Study, site re-appraisal should be conducted for the potentially contaminated sites once site access is available (e.g. after land resumption) in order to identify the need for SI for any additional hotspots as a result of the on-going land contaminating activities.  In addition, re-appraisal would be required for the other remaining areas of the proposed YLSEPP site to assess the latest site situation in order to address any change in land use that may give rise to potential land contamination issues.

7.8.1.2           Findings of the re-appraisal and strategy of the recommended SI, if required, will be presented in a supplementary CAP.  Upon approval of the supplementary CAP and completion of the SI works, a Contamination Assessment Report (CAR) would be prepared to present findings of the SI works.  If contamination has been identified, a RAP would be prepared to recommend specific remediation measures.  Upon completion of the remediation works, if any, a Remediation Report (RR) would also be prepared to demonstrate that the clean-up works are adequate.  The CAR, RAP and RR would be submitted to EPD for approval prior to commencement of any construction / development works at the identified contaminated sites.

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 sites 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 sites. 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 YLS EIA Study, further desktop review and site walkover, was conducted from August 2020 to September 2021 to identify any potentially contaminating land uses within the proposed YLSEPP site.  Based on the site appraisal findings, 23 potentially contaminated sites are located within the proposed YLSEPP site.

7.11.1.2        Similar to the recommendation in the YLS EIA Study, as the potentially contaminated sites were inaccessible and still in operation, and there could be changes in site operation or changes in land use within the proposed YLSEPP site prior to development which may cause potential land contamination issues, site re-appraisal for the potentially contaminated sites within the proposed YLSEPP site should be conducted once site access is available (e.g. after land resumption) in order to identify the need for SI for any additional hotspots as a result of on-going land contaminating activities. In addition, re-appraisal would be required for the other remaining areas of the proposed YLSEPP site to assess the latest site situation in order to address any change in land use that may give rise to potential land contamination issues.  The further works including site re-appraisal for the whole proposed YLSEPP site, associated SI works, any necessary remediation works and submission of supplementary CAP / CAR / RAP / RR are recommended to be carried out when site access is available (e.g. after land resumption) but prior to commencement of any construction or development works at the identified contaminated sites, 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 would be identified and properly treated prior to the construction works.  No insurmountable land contamination impacts to the Project are therefore anticipated.