6 LAND CONTAMINATION IMPACT

6.0.0.1 This Section presents the results of the investigations into the potential environmental issues related to land contamination, and where appropriate, identifies areas for further assessment in the subsequent construction phases of the Deep Bay Link (DBL).

6.0.0.2 The main objectives of the land contamination investigation are to:

• provide an clear account on the past land use history, as far as possible, and the present uses of the land in question, in relation to potential land contamination;
• identify those areas of potential contamination and associated impacts, risks or hazards;
• evaluate potential impacts and extent of contamination and selection of appropriate cleanup technologies;
• submit a Contamination Assessment Plan (CAP) to evaluate the actual contamination conditions for soil and/or groundwater.

6.1 Legislation, Policies, Plans, Standards and Criteria

6.1.0.1 Assessments of land contamination and the potential impacts are guided by the EPD's document Professional Persons Environmental Consultative Committee Practice Note 3/94 - Contaminated Land Assessment and Remediation (ProPECC PN 3/94), the Technical Memorandum on Environmental Impact Assessment Process (EIAO-TM), and the EPD's 1999 Guidance Notes for Investigation and Remediation of Contaminated Sites of: Petrol Filling Stations, Boatyards, and Car Repair/Dismantling Workshops (Guidance Notes). In accordance with these documents, the assessment evaluation should:

• provide a clear and detailed account of the present use of the land in question and the relevant past land use history, in relation to possible land contamination;
• identify those areas of potential contamination and associated impacts, risks or hazards; and
• as required, submit a plan to evaluate the actual contamination conditions for soil and/or groundwater

6.1.0.2 Under the ProPECC PN 3/94 note and the Guidance Notes, and in the absence of any formal legislation requiring cleanup of soil and groundwater contamination in Hong Kong, the "Dutch Ministry of Housing, Planning and Environmental Soil and Groundwater Standards" (the Dutch Guidelines) (1994) are used as reference criteria by the EPD for the classification of contaminated materials. It should be noted that the Dutch Guidelines, whilst widely recognised and generally applicable on a global scale, are not enforceable standards in Hong Kong. In the Netherlands, the Dutch Guidelines were developed in the specific case where the drinking water supply is source entirely from groundwater. Hence, the Dutch Guidelines are very strict in regard to some specific contaminants, but must be viewed in the relative context of the Hong Kong situation.

6.1.0.3 Under the EIA Ordinance, Annex 19: Guidelines for Assessment of Other Impacts, and the 1999 Guidance Notes, consideration shall be given to a number of potentially contaminating historical land uses, including petrol filling stations, oil installations, shipyards/boatyards, car repairing and dismantling, power plants and gas works. If these land uses are identified, then the applicant is required to generate a Contamination Assessment Plan (CAP).

6.1.0.4 The following legislation, documents and guidelines may also cover or have some bearing upon land contamination and the handling, treatment and disposal of contaminated waste in Hong Kong:

• Water Pollution Control Ordinance (WPCO);
• Waste Disposal Ordinance (Cap 354);
• Waste Disposal (Chemical Waste) (General) Regulation (Cap 354); and
• Code of Practice on the Packaging, Labelling and Storage of Chemical Wastes, Environmental Protection Department (1992).

6.2 Description of Environment

6.2.0.1 The DBL passes through a variety of land uses along its proposed alignment. At the Ngau Hom Shek end of the alignment (Figure 6.1a), the uses are mainly residential areas, fields, fish ponds, livestock farms, hillside and some workshops / open storage areas.

6.2.0.2 For the area of the proposed Ha Tsuen Interchange (Figure 6.1a) the current land use are mainly open storage of mixed materials and machinery, car repair and dismantling area and workshops.

6.2.0.3 Areas south to the San Wai Sewage Treatment Works (Figure 6.1a) are mainly open storage for cargo containers, and some farms and abandoned green areas.

6.2.0.4 Areas further south (Figure 6.1b) is made up of open storage sites of mixed materials, workshops, car repair and dismantling sites, farms, pigeon farms, and a concrete batching plant nearby.

6.2.0.5 Areas near Lam Tei Interchange and Yuen Long Highway (Figure 6.1c) where the alignment will pass through are mainly residential with village/squatter houses. Near Fuk Hang Tsuen, the alignment encroaches workshops of mixed nature, including car repairing and dismantling sites, hardware manufacturing sites etc. At the Lam Tei Interchange, many of the residential areas are 1-3 storey houses with a small field / farm area nearby.

6.2.0.6 Most of the land being used/resumed are those directly encroached by the alignment (the affected land), or those just next to the affected land. Typically the affected area or work areas will be 30m or less from both sides of the alignment.

6.3 Assessment Methodology

6.3.0.1 The objective of the current land contamination study is to identify and screen any concerns with respect to potential soil and groundwater contamination along the proposed DBL alignment.

6.3.0.2 The following methodology has been adopted in this land contamination study:

• preliminary review of the current and historical land uses to evaluate the likely level of potential for any soil and ground contamination;
• description of the likely nature of any potential contamination;
• a preliminary review of potential environmental impacts or health concerns arising as a result of the development or during future use of the land, as a result of exposure to potentially contaminated materials; and
• overview of typical mitigation measures.

6.3.0.3 During this study reference to the following sources of information was made:

• Selected aerial photographs along the alignment route from 1945 to 1999;
• correspondence with various Government Departments;
• Hong Kong Ordinance Survey maps along the proposed alignment;
• records and photographs from site visits.

6.3.0.4 A list of the aerial photographs reviewed during the course of the study is presented in Table 6.1 below. The photographs are reviewed for general changes in land use, as well as specific development.

6.4 Identification, Prediction and Evaluation of Potential Impacts

6.4.1 Sources of impact

6.4.1.1 The DBL project requires the taking over of some of the existing government land and private land for the construction of roads and carriageways. Much of the road alignment will be formed on existing hillside or agricultural land. A minor portion of land which DBL will run through is occupied by workshops and open storage sites. Depending on the nature of these operations, potential contaminants may enter the soil and groundwater to varying extent, which may lead to land contamination impact. However, DBL is comprised of mainly elevated roads and carriageways which are relatively insensitive to land contamination. Impact of land contamination may only be apparent during the construction phase when the suspected sites within the foundation areas are disturbed.

6.4.2 Review of Historic and Current Land Uses

6.4.2.1 A review of selected historical aerial photographs indicates that the majority of land along the proposed alignment and its associated facilities has primarily been used for farms, fish ponds and residential uses (e.g. Ngau Hom Shek, Lam Tei Interchange), and storage area of cargo containers (near San Wai Sewage Treatment Works). Table 6.2 below lists the historical change in land use in these major areas.

6.4.3 Potential Sources of Land Contamination

6.4.3.1 Potential sources of land contamination along the DBL alignment and its vicinity are presented in Figure 6.1, and the details are summarized in Table 6.3.

6.4.3.2 Field visits revealed that the majority portion of the land where DBL is located or requires would have relatively low potential for land contamination impacts. Several sites were identified which would require further investigation and they are:

(i) Area C1 near proposed helipad
(ii) Area C3 near propose road to helipad
(iii) Area D near Ha Tsuen Interchange
(iv) Area F under the alignment of DBL south to San Wai Sewage Treatment Works
(v) Area G under the alignment of DBL south to San Wai Sewage Treatment Work
(vi) Area J under the alignment of DBL along Fuk Hang Tsuen Road
(vii) Area L at Lam Tei Interchange
(viii) Area M at Lam Tei Interchange
(ix) Area K at Lam Tei Intechange
(x) Area B near the proposed

6.4.3.3 Further contamination assessment at the above sites should follow the requirements laid out in the proposed contamination assessment plan.

6.4.3.4 For Area K and Area B, further inspection is required when access to the site is available, probably after the land is available to DBL. The inspection aims to identify if there is likely land contamination through site appraisal.

6.4.4 Proposed Contamination Assessment Plan

6.4.4.1 It is not possible to make access to some private land lots for these concerned sites at this stage of study since the sites are still in operation. Considering most sites are open sites without roof or cover, weather conditions e.g. flooding or rains and future activities would likely to change the level of contamination. An outline of the Contamination Assessment Plan (CAP) was worked out for further investigation that would be conducted before the construction stage (probably immediately after the land is made available to DBL).

6.4.4.2 Table 6.4 lists the parameters that should be analysed, and the number of samples to be taken at each identified area (according to EPD's Guidance Notes for Investigation and Remediation of Contaminated Sites). All the information given in Table 6.4 (including the number and location of sampling points and testing parameters) should be reviewed during the preparation of Contamination Asessment Plan.

6.4.4.3 The Contamination Assessment Plan (CAP) shall be prepared and submitted to EPD for endorsement prior to conducting the site investigation. A Contamination Assessment Report (CAR) should be prepared based on results obtained from site investigation and submitted to EPD.

6.5 Mitigation of Adverse Impacts

6.5.0.1 Concerned sites have been identified in the previous section. Contamination assessment should be carried out to determine whether the sites are contaminated and what level of contamination is present.

6.5.0.2 Potential impacts from these sites are to be determined by the level of contamination present and the possible pathway of exposure by sensitive receivers. Since DBL is comprised of mostly elevated road and carriageways, potential concern would be limited to the exposure during the disturbance of soil in construction phase where foundation are located. Provided that the Contamination Assessment Plan would investigate and identify the contamination level, a Remedial Action Plan could be formulated to remediate the soil to an accepted level. No residual impact is expected after necessary remediation.

6.5.0.3 Available methods of remediation include but not limited to:

Excavation / Disposal

The principle use of this method is for shallow contamination, one-off excavation and contaminant removal. It addresses all contaminants, and pretreatment of excavated soil prior to disposal may be required.

Soil Venting / Air Sparging

The principle use of soil venting is for volatile contaminants in the unsaturated zone soils. Air sparging is mainly for groundwater treatment. These methods remove volatile chemicals and promote bioremediation.

Recovery Trenches or Wells

The principle use of this method is to remove leaked oil that floats on top of groundwater. It is a prerequisite use in conjunction with other remediation methods if leaked oil is found.

Containment of Contaminants

Due to the limitation of available landfill space for disposal of contaminated materials in Hong Kong, the EPD suggests that in-situ remediation methods should be used wherever possible. Contaminament of contaminants is one of the in-situ methods. Excavation and disposal should be the last resort and only used when (1) in-situ remediation is proved to be not feasible and (2) there is very localised contamination and the quantity of contaminated soil for landfilling is small.

6.5.0.4 The acceptance of disposal of contaminated soil at landfill also depends on the degree of contamination of the soil and the nature of the contamination. Special approval has to be obtained from the EPD for disposal to landfill. In some cases, the contaminated soil must be pretreated. According to the EPD's Guidance Notes document, the following factors should be considered when evaluating the different remediation methods and selecting the most suitable one for a site:

• Degree and extent of the contamination;
• Anticipated future uses of the site;
• Nature of the contaminants;
• Soil characteristics; and
• Time available for remediation.

6.5.1 Mitigation Measures During Construction Phase

6.5.1.1 It is considered unlikely that contaminated land issues will be a concern during either the construction or the operation of the DBL alignment as remediation on contaminated area would be carried out prior to construction. However, as a precaution, it is recommended that standard good practice be implemented during the construction phase to minimise any potential exposure to contaminated soils or groundwater. These measures include:

• The use of bulk earth-moving excavator equipment would minimise construction workers' potential contact with contaminated materials;
• Exposure to any contaminated materials may be minimised by the wearing of appropriate clothing and personal protective equipment such as gloves (when interacting directly with suspected contaminated material), providing adequate hygiene and washing facilities and preventing smoking and eating during such activities;
• Vehicles containing any excavated materials should be suitably covered to limit potential dust emissions or contaminated wastewater run-off, and truck bodies and tailgates should be sealed to prevent any discharge during transport or during wet conditions;
•  Only licensed waste haulers should be used to collect and transport any contaminated material to an appropriate disposal site and procedures should be developed to ensure that illegal disposal of waste does not occur;
• The necessary waste disposal permits should be obtained, as required, from the appropriate authorities, in accordance with the Waste Disposal Ordinance (Cap 354), Waste Disposal (Chemical Waste) (General) Regulation (Cap 35), as required;
• Records of the quantities of wastes generated and disposed of should be maintained; and
• In accordance with good construction practice, silt traps should be used to reduce the impact to drainage caused by suspended solids arising from disturbed ground, or any construction materials such as cement and gravel. Groundwater should be disposed of in accordance with the WPCO.

6.6 Conclusion and Further Investigation

6.6.0.1 This preliminary investigation has identified land uses along the proposed DBL alignment with the potential to give rise to land contamination as defined in the EPD guidance documents. A preliminary Contamination Assessment Plan (CAP) is prepared and included within the EIA under Annex 19 of the EIAO TM and the 1999 Guidance Notes.

6.6.0.2 Considering the rapid changing of landuses in the areas, the CAP should be updated with reference to concurrent site conditions. It would be necessary to carry out a site apprasial to review the findings of this EIA before construction work starts and confirm the exact sampling locations and testing parameters. This should be included in the finalised CAP in agreement with EPD. Upon receipt of the EPD's approval, the CAP will be implemented and the findings of the investigations will be reported in the Contamination Assessment Report (CAR).

6.6.0.3 The results of the sampling exercise would determine whether contaminated land is, in fact, an issue that needs to be addressed further. If results from sample analysis indicate the presence of potential contaminants, then it may be necessary to update or amend the current CAP in light of the findings. If land contamination is confirmed, a Remediation Assessment Plan (RAP) shall be prepared, and both the CAR and the RAP shall be submitted as a combined report to the EPD for approval prior to the implementation of any remedial technology. If applicable and required in consultation with the EPD, the contaminated site shall be remediated in accordance with the approved CAR/RAP.

6.6.0.4 Implementation of the RAP can begin once the CAR and RAP submission are approved by the EPD. The essential steps involved in remedial programme are detailed in the EPD's Guidance Notes document. In all cases, contaminated soil remediation, treatment or disposal of it must be managed in an environmentally sound manner, including compliance with all relevant legislation and Government requirements.

6.6.0.5 The CAP together with the sampling and testing work are planned to start after the land is available to DBL through early negotiations or resumption and the subsequent CAR and RAP shall be approved by the EPD before commencement of any construction work which may disturb the ground of the concerned sites. Contaminated soil should be remediated before construction work could be started on the concerned sites. It would take about one month to complete the CAP and another two months to complete the CAR and RAP.