9.1.1. This section identifies the potential land contamination that may arise during construction and operation phases of the proposed Project. The potential environmental impacts associated with land contamination will also be assessed in accordance with the criteria and guidelines as given in Section 3.1 and 3.2 of Annex 19 of the EIAO-TM as well as clause 3.4.9 and Appendix E2 of the EIA Study Brief (No. ESB-267/2014).
9.2.1. The following three EPD publications provide guidance in relation to land contamination assessment:
· Guidance Note for Contaminated Land Assessment and Remediation (Guidance Note);
· Guidance Manual for use of Risk-based Remediation Goals (RBRGs) for Contamination Land Management (Guidance Manual); and
· Practice Guide for Investigation and Remediation for Contaminated Land (Practice Guide).
9.2.2. The Guidance Note sets out the requirements for proper assessment and management of potentially contaminated sites, provides guidelines on how site assessment should be conducted and suggests remedial measures for the clean-up of contaminated sites.
9.2.3. The Guidance Manual presents the background of RBRGs and the application of RBRGs in land contamination assessment.
9.2.4. The Practice Guide presents the standard investigation methods and remediation strategies for the range of potentially contaminated sites and contaminants typically encountered in Hong Kong.
9.3.1. The proposed Project is planned to be constructed on a piece of land which is currently allocated as a works and staging area of the Drainage Services Department (DSD). It is surrounded by Sheung Tat Street to the northwest, the Sheung Mau Street to the southwest and Sheung On Street to the southeast.
9.3.2. Existing facilities nearby include the New World First Bus Chong Fu Road Permanent Depot (NWFB) to the northeast, ExxonMobil Petrol-cum-LPG Filling Station immediate to the southwest and Citybus Depot further to the southwest.
9.3.3. Based on the best available information at the time of the EIA study, no major change in the existing environmental condition is anticipated in the future in the absence of the proposed Project.
9.4.1. The land contamination assessment was conducted with reference to the Practice Guide issued by EPD. The general procedures of the assessment include:
· Carrying out site appraisal (information collection);
· Designing site investigation and preparing Contamination Assessment Plan (CAP) for EPD’s approval;
· Conducting site investigation;
· Interpreting results and preparing Contamination Assessment Report (CAR) for EPD’s approval;
· Planning, designing remediation measures and preparing Remediation Assessment Plan (RAP) for EPD’s approval; and
· Preparing Remediation Report (RR) for EPD’s endorsement.
9.5.1. A site appraisal had been conducted to review the existing and historical land uses that may impact the Project site in order to identify the potential contamination sources, if any, within the Project site and its surroundings due to past and current uses.
9.5.2. The following sources of information have been collected and reviewed to ascertain the potential on-site and off-site activities that can contribute to land contamination at the Project site:
· Aerial photographs from Lands Department (LandsD) taken twice every five years between 1975 – 2013;
· Acquisition of information related to potential land contamination from the Environmental Compliance Division of EPD, Fire Services Department (FSD), District Lands Office (DLO) and NWFB Depot;
· Ground investigation records near the Project site; and
· Records and photographs from site walkover.
9.5.3. Historical aerial photographs from 1975 to 2013 (Figure 9.1) available in the Survey and Mapping Office at LandsD have been reviewed to identify the potential historical activities that could result in contamination of site.
9.5.5. Aerial photographs in 1989 and 1994 reveal that the Project site became temporary housing area. As indicated in the aerial photograph taken in 1999 and 2004, the temporary housing area was demolished and the Project site was further developed into a public carpark. The Project site has no undergone much change since then.
9.5.6. Land use summary from 1988 to present were also obtained from the DLO as shown in Table 9.1. The development history of the Project site confirms with that shown in aerial photographs as discussed above. The Project site recently served as a temporary works and staging area for the DSD.
9.5.7. Record of land use history prior to 1988 at the Project site cannot be traced, as formal confirmed by the DLO and Port Works Division of the Civil Engineering and Development Department (CEDD). As discussed in Section 9.5.4 above, land reclamation of the Project site and other sites on Sheung On Street was still in progress.
Table 9.1 Summary of Historical and Current Land Uses
|
Period |
Previous / Existing Use |
|
1984 - 1988 |
Land Reclamation in Progress(1) |
|
1988 - 1997 |
Sheung On Temporary Housing Area (THA) |
|
2001 - 2002 |
Temporary works area for road construction
project in Chai Wan Reclamation Area |
|
2003 - 2004 |
Fee-paying public car park |
|
2005 - Present |
Temporary works area for Drainage Maintenance
and Construction in Hong Kong Islands and Islands Districts |
[1] Refer to aerial photographs taken in 1975, 1979 and 1984
9.5.9. Information regarding current and past registration of dangerous goods (DGs) records was requested from FSD for review. According to the information provided by FSD, there has not been record of dangerous goods storage within the Project site since 1990 and fire and special services incident in the past three years.
9.5.10. According to the information provided by the Environmental Compliance Division of EPD, there are no registered chemical waste producers at the Project site. Furthermore, no record of chemical spillage within the past 5 years has been identified.
9.5.11. As confirmed by New World First Bus Services Ltd., there has not been any land contamination issues arising from the adjacent NWFB Depot since it came into operation in 2001. A similar reply from New World First Bus Services Ltd. also confirmed that there has been no reported incident of land contamination caused by Citybus Depot since its operation in April 2004.
9.5.13. Written reply from District Lands Office confirmed that the current user of the Project site, the Director of Drainage Services, is required to reinstate the Project site and hand back the Project site to the District Lands Office free of structure/debris and cleared of all occupation.
9.5.14. Ground investigation (GI) was conducted in 1990 at a site approximately 100m to the northeast of the Project site which was further turned into NWFB Depot. A total of five vertical drill holes and two trial pits were drilled to study the general sequence of strata. The maximum depth of vertical holes drilled was 69.92m below ground level. According to the GI records, fill materials ranged in a thickness from 13m to 16m below ground level. Directly underneath the fill materials lie the marine deposit / alluvium. Copies of the drill holes and trial pit records are provided in Appendix 9.2.
9.5.15. As no major earthworks are required for site formation works of the proposed Project, the anticipated amount of excavated materials to be generated is limited to topsoil only. In view of the above findings, it is expected that the construction phase of the proposed Project will not lead to any potential land contamination issue.
9.5.16. Site walkover was carried out on 28th October 2013 at the Project site with the participation of an authorized representative from Welcome Construction Co., Ltd. (term contractor of DSD). Checklist of the site walkover is provided in Appendix 9.3.
9.5.17. It was observed from the site walkover that the whole site was paved by concrete and the pavement was in good condition (no oil stains and cracks). There was parking of contract vehicles and storage of construction materials such as aggregate, drainage pipes, manhole covers, cement, milled asphalt, etc. No storage of diesel and oils except a few sealed containers of lubricant were identified within the site boundary during the site walkover. Designated waste disposal area for temporary storage of excavated materials from drainage maintenance works was also identified. Since the Project site was paved, infiltration of any oils / chemical from spillage / leakage incidents were found to be unlikely.
9.5.18. It is noteworthy that past environmental inspection records from DSD’s term contractor revealed that there were temporary on-site storage of 2 to 3 drums of diesel / gasoline in the past at location as shown in Appendix 9.4 for refilling plants and vehicles under very rare occasion. However, no crack / stain was observed and documented at the concerned storage area by DSD’s term contractor. In addition, there has also been no record of chemical spillage / leakage at the Project site according to DSD’s term contractor and local authorities as summarised in Section 9.5.8 to 9.5.12 above. The potential land contamination issue attributed to the temporary storage of diesel/gasoline in the past is therefore not anticipated.
9.5.19. The site appraisal reveals that the present land use of the Project site is not anticipated to have caused spillage and leakage of chemical and dangerous goods, and the concrete-paved ground is expected to have minimised possible land contamination. Moreover, no potential contamination arising from the past activities at the site was identified. Therefore, it is concluded that subsequent soil and groundwater sampling and remediation at the construction phase (i.e. Step 3 to 6 of the land contamination assessment) is considered not necessary for the Project site in this EIA study.
9.6.1. Since no potential contamination arising from the past activities at the site was identified as mentioned in Section 9.5, mitigation measure is not required. Nonetheless, preventive measures are recommended to be implemented.
9.6.2. The Guidance Note identifies the following industries as having potential for causing land contamination:
· Oil installations (e.g. oil depots, petrol filling stations);
· Gas works;
· Power plants;
· Shipyard / boatyards;
· Chemical manufacturing / processing plants;
· Steel mills / metal workshops;
· Car repairing / dismantling workshop; and
· Scrap yards.
9.6.3. In view of the nature of the proposed Project, the potential sources of land contamination during operation are identified as follows:
· Vehicle washing bays;
· Vehicle repair / testing areas;
· DGs and chemical storage areas; and
· Chemical waste storage areas.
9.6.4. A total of approximately 20m2 designated areas will be provided to store DGs. The quantity of on-site storage of DGs due to daily operation of the GL Specialist Laboratory is as follows:
· DGs Category 2: 10 cylinders per month
· DGs Category 3: 20kg and 100L per month
· DGs Category 5 (Division 1): 160L per month
· DGs Category 5 (Division 2): 210L per month
Designated Storage Areas
9.6.5. Chemical waste will be stored in designated storage areas in accordance with EPD’s Waste Disposal (Chemical Waste) (General) Regulation and Code of Practice on the Packaging, Labelling and Storage of Chemical Waste;
9.6.6. The proposed Project will be covered, except the landscape area on Level 1 and the roof floor, and properly paved by concrete. The storage area for liquid chemical waste containers should have an impermeable floor or surface made of suitable materials. The storage area should be kept clean and dry;
9.6.7. Where the storage area is not located within the premises in which chemical waste is produced, the storage area should be kept secured with an appropriate door/gate and locked at all time;
9.6.8. Containers should be checked for leakage or spillage before use; and
9.6.9. Drainage management system such as oil/petrol interceptors will be incorporated in the proposed Project for on-site treatment and removal of DGs, chemical and waste.
Procedures for Waste Disposal
9.6.10. Chemical wastes will be regularly removed from the proposed Project in accordance with Code of Practice on the Packaging, Labelling and Storage of Chemical Wastes. The contractor of the chemical waste treatment centre (CWTC) is expected to collect waste chemical from the laboratory on a weekly basis.
Emergency Procedures
9.6.11. Any spillage and / or leakage incident must be reported to the future operator of the proposed Project who should attend to the spillage and initiate any immediate actions required to protect workers and to confine and clean up the spillage.
Spillage / Leakage of Liquid Chemical / Waste at Storage Area
9.6.12. Where the spillage / leakage is contained in the enclosed storage area, the material should be transferred to suitable containers by appropriate equipment, e.g. hand-operated pumps, scoops or shovels. If the spillage / leakage quantity is small, it should be covered and mixed with suitable absorbing materials. The resultant slurry should be treated as chemical waste and transferred to suitable containers for disposal.
9.6.13. Areas that have been contaminated by chemical waste spillage/leakage should be cleaned. While water is a suitable solvent for aqueous chemical wastes and water soluble organic waste, kerosene or turpentine should be used for organic chemical wastes that are not soluble in water. The waste from the cleanup operation should be treated and disposed of as chemical waste.
9.6.14. In incidents where the spillage/leakage may result in significant contamination of an area or risk of pollution, the EPD should be informed immediately.
Spillage / Leakage at Other Areas
9.6.15. For spillage/leakage in other areas, immediate action is required to contain the spillage/leakage. Suitable liquid absorbing materials such as tissue paper, dry soft sand or vermiculite should be used to cover the spill. The resultant slurry should be treated as chemical waste and transferred into containers for proper disposal.
Record of Incidents
9.6.16. An incident logbook detailing the estimated amount of each spillage and / or leakage incident shall be compiled and maintained by future operator of the proposed Project. The incident logbook will be used to evaluate the corresponding environmental impacts arising from each specific spillage and / or leakage incident.
9.7.1. Since no significant land contamination impacts are predicted during the construction and operation phases of the proposed Project, adverse residual impacts will not be anticipated.
9.8.1. As the land contamination at the Site was identified to be insignificant during construction and operation phases with the implementation of good site practice and design, no EM&A for land contamination is recommended.
9.9.1. The land contamination assessment was undertaken by reviewing historical and current land uses and site reconnaissance. With reference to the findings of the site appraisal, there is no sign of land contamination due to past and current activities at the Project site.
9.9.2. The operation of the proposed Project is not anticipated to lead to quantifiable adverse land contamination impacts with proper site practice for handling, storage, transportation, collection and disposal of DGs, chemical and chemical waste.
9.9.3. However, since the construction works of the proposed Project will only commence in Mid 2016 the earliest, land contamination assessment and any necessary remediation work will be required to be carried out by the contractor if there is any sign of land contamination issue identified prior to or during the construction phase of the proposed Project. The land contamination assessment and associated remediation works must be in accordance with EPD publications as summarised in Section 9.2.