9. CONTAMINATED LAND ASSESSMENT

Introduction

9.1 Contamination can be defined as "the introduction by man into the environment of substances or energy liable to cause hazards to human health, harm to living resources and ecological systems, damage to structures or amenity, or interference with legitimate uses of the environment" (Holdgate 1979, and adopted by the RCEP, 1984). The soil is a primary recipient, intended or otherwise, of many waste products and chemicals used in modern society.

9.2 The Spur Line passes across a range of landuses, including agricultural, residential, container storage, industrial and fish farming areas. While there are no extensive areas of contaminated land such as landfills, chemical stores, etc. across which the Spur Line passes, there is potential for the presence of small industries or storage sites to create an impact in the construction and operation of the Spur Line. This contaminated land assessment has been written to present the potential impact from the presence of contaminated land on the Spur Line project in accordance with EPD Practice Note for Professional Persons Concerning ProPECC PN 3/94 - Contaminated Land Assessment and Remediation and the EPD Guidance Notes for Investigation and Remediation of Contaminated Sites of: Petrol Filling Stations, Boatyards or Car Repair/Dismantling Workshops.

Methodology

9.3 This contaminated land assessment includes the following steps:

(i) A desktop study on the history of landuse along the Spur Line alignment (the Desktop Study) which provides a clear and detailed account of the relevant past land history and the present land uses along the alignment. This identifies areas of potential land contamination.

(ii) A site survey in order to identify potential 'hot spots' and pollutants for the land contamination assessment.

(iii) Recommendations for a schedule of 2 stage sampling, initially at potential “hot spots” identified in the Desktop Study and during the site survey followed by grid sampling if contamination is confirmed, and the laboratory analysis of essential parameters. This should be carried out at the site investigation stage of works to confirm the presence or absence of contamination.

(iv) Recommendations on appropriate remedial action for several scenarios based on the range of different types of contaminants which may be found during site investigations. Any remedial action proposed will be beneficial not only in terms of preparing the land for construction but will also alleviate potential impacts on groundwater, water quality in river courses and the ecology of the area.

(v) The application of the recommended sampling, analysis and remediation programme to specific locations along the alignment to facilitate the implementation of the Contamination Action Plan during the site investigation stage.

Study Area

9.4 The Study Area includes the direct track alignment and the engineering works boundary (Figure 2.1). Three temporary works areas have been earmarked at Lok Ma Chau, Kwu Tung and at the Sheung Shui Temporary Housing Area. In the Lok Ma Chau area, fishponds will require temporary draining and stabilisation with partial or complete infilling to create a base for pier and station foundation works.

9.5 Most of the alignment passes through rural areas dominated by agriculture. In these areas the potential for contamination is minimal. However, around Sheung Shui and in Kwu Tung a number of small industries and storage areas exist. At the Lok Ma Chau end of the alignment are a number of container storage yards which may contribute to land contamination.

9.6 The total alignment will include viaduct across low-lying areas such as Long Valley and Lok Ma Chau fishponds and at grade, cutting and embankment sections as it passes through Kwu Tung, Pak Shek Au and Chau Tau. Details of the alignment are provided in Chapter 21. The type and suitability of mitigation measures in a potentially contaminated site is largely determined by whether the alignment is at grade, in a cutting, on embankment or on viaduct.

9.7 Construction methods will include foundation works for the viaduct supports and for Lok Ma Chau station construction, bored piling works, and excavation of material along the sections at grade and in cutting.

Risks to Health

9.8 A contamination assessment is important because of the health risks posed to site workers on exposure to contaminated soil or sediments, and contamination of groundwater during earth moving operations, excavation or piling works. Workers could become exposed to contaminants either directly e.g. skin contact during the work by inhalation of dust or vapours, or through ingestion whilst eating or smoking on site.

9.9 If remediation is found to be necessary at any point of the alignment it should be carried out to a suitable level so as not to pose any future health risks to users of the site. As long as there is no direct human - soil interface, it is likely that in many places the sediments could remain in-situ or be remediated to a level sufficient for its future use.

9.10 Contaminants of particular concern due to their potential health risks include inorganics such as cyanides and heavy metals, organics such as mineral oils, halogenated solvents, polycyclic aromatic hydrocarbons and volatile aromatic hydrocarbons and minerals such as asbestos.

9.11 Contaminants may also pose a fire hazard or explosion risk if volatile gasses or flammable contaminants are found.

Desktop Study

Industries Having the Potential to Cause Land Contamination

9.12 Historically there is evidence that the New Territories was the location for various light industries and other landuses which change frequently but often have a potential to contaminate the land. These include car repair yards, container storage areas, livestock farms, paint and dye factories and other small scale industries. Many of these small industries still operate today, although the density of factories has reduced over recent years. In addition there are dumping grounds, refuse collection points and illegal dumping areas which are likely to result in some ground contamination. Many of these landuses fall within the areas of the proposed alignment and, if unmitigated, give rise to concern for their future landuse.

9.13 A number of industries have been identified in ProPECC PN 3/94 as having the potential to cause land contamination. These include:

· oil installations (e.g. oil depots, oil filling stations);

· gas works;

· power plants;

· shipyards/boatyards;

· chemical manufacturing/processing plants;

· steel mills/metal workshops; and

· car repairing/dismantling workshops.

9.14 This list is not exhaustive and judgement is needed to determine if contamination is likely from other land uses or industries. For example, there are several sites along the Spur Line alignment where chemicals used to treat leather are stored. Such solvents are known to be hazardous to the environment (LaGrega, 1994).

Land Ownership

9.15 There is a variety of ownership along the alignment of the Spur Line. Across Long Valley there are many agricultural lots, whilst in Kwu Tung many owner occupied small houses typical of the New Territories are found. Significant Some areas of land along the alignment are Government Land, particularly in the Lok Ma Chau and Sheung Shui areas. However, the latter Government-owned areas are generally not the areas of potential contamination.

Landuse History

9.16 In order to assess potential land contamination, the past landuse history and the present landuse of the areas which will fall under the Spur Line alignment have been reviewed. Aerial photographs have been used and landuse information has been obtained from the District Land Offices in Yuen Long (DLO Yuen Long) and Fanling (DLO North).

Site Survey

Objectives and Methodology

9.17 The objectives of a site survey for the land contamination assessment are to confirm any land-uses found in the DLO records and to identify any other uses which may be illegal and not recorded. The site survey has also been used to gather information on other activities such as storage and management of hazardous substances.

9.18 Site inspections were carried out on 17 May and 27 July 1999. No advance notice was given to land users in order to obtain as authentic information as possible. A number of sites along the alignment were disregarded due to information obtained during the desktop study and site visits which indicated no likelihood of contamination. The findings of the site survey are evaluated to identify potential "hot spots" and parameters for further investigation in a sampling and analysis programme.

9.19 Ground conditions were also observed during the site surveys, to determine the ease of infiltration and potential for underground dispersion of pollutants.

Results of Desktop Study and Site Visits

9.20 A full listing of the desktop study results and the findings of site visits to each site are provided in Appendix K. As some sites cover more than one lot, each site listed has been assigned a letter. The sites are described from west to east along the alignment and their location identified in Figures 9.1 9.2 9.3. The nature of the land in each lot, and the activities being carried out which may potentially contaminate the ground, are shown in Plates 9.1 to 9.32. Not all lots could be photographed, however, a description of each lot is given in the following tables. Table 9.1 lists lot numbers, their assigned letter and whether each site is at grade, on viaduct or through cutting.

Table 9.1 Lot Numbers, Assigned Letters and Elevation

Letter	Lot Number	Elevation	Letter	Lot Number	Elevation
A (i)	DD99/372 S.D RP - Northern Section	Viaduct	K L	DD 96/717, 718, 721 Government Land north of Po Lau Road	Cutting At GradeEmbankment
A (ii)	DD99/372 S.D RP - Southern Section	Viaduct	L M	Government Land north of Po Lau Road DD95/ 786, 791, 792, 772 (part)	At Grade
B	DD99/ 470 - 483, 486 - 493, 527, 545 - 548	At Grade Embankment/ Viaduct	M N	DD95/ 786, 791, 792, 772 (part) DD96/ 772 (part)	Viaduct
C	DD96/352, 353, 354, 355, 423	At GradeEmbankment	N O (i)	DD96/ 772 (part) DD95/ 801 S.A. ss.1 RP	Viaduct
D	DD96/ 428	At GradeEmbankment	O (i) O (ii)	DD95/ 801 S.A. ss.1 RP DD95/ 801 S.A. RP	Viaduct
E	DD96/2250	At GradeEmbankment	O (ii) P	DD95/ 801 S.A. RP DD95/ 803 S.A. ss.	Viaduct
F, G	DD 96/62145 – sections	At GradeCutting	P Q	DD95/ 803 S.A. ss. DD95/ 803 S.A. ss.2, 803 S.A. RP and 803 S.A. ss.3	Viaduct
G H	DD 96/645 - sections DD 96/702	Cutting	Q R	DD95/ 803 S.A. ss.2, 803 S.A. RP and 803 S.A. ss.3 DD95/ 803 S.B.	Viaduct
HI	DD 96/702 DD 96/704, 705, 709, 716	Cutting	R S	DD95/ 803 S.B. DD95/ 1994	Viaduct
IJ	DD 96/704, 705, 709, 716 DD 96/698, 699	Cutting	S T	DD95/ 1994 DD95/ 43 - 45, 53 - 59, 65 - 67, 70 - 74	Viaduct
JK	DD 96/698, 699 DD 96/717, 718, 721	Cutting	TU	DD95/ 43 - 45, 53 - 59, 65 - 67, 70 -– 74DD96/717, 718, 721	ViaductCutting/Works Area

9.21 Table 9.2 summarises the results of the desktop study and site visits. The table lists the registered landuse of the site and the likely potential and extent of contamination. Appendix K includes any permit numbers or Short Term Tenancy Agreements (STT) or Short Term Waivers (STW) which cover the lots.

Table 9.2

Findings of Desktop Study & Site Visits and the likely Potential for Contamination

Site and Lot No.	Figure No. / Plate No	DLO Registered Landuse	Site Inspection	Potential for Land Contamination
A DD99/372	Figure 9.1 Plates 9.1 - 9.5	Container vehicle park, open storage	Confirmed landuse. Some petrol pumps, chemical waste area	Likely, rough surface, cracked concrete, storage of chemical and hydrocarbons on site
B DD99/470-483, 486-493, 527, 545-548	Figure 9.1 Plates 9.6 - 9.9	NA*	Containers, open storage, storage of chemicals, oils and solvents	Likely, gravel and cracked surface and storage of potential contaminants and scrap metals
C DD96/352, 353, 354, 355, 423	Figure 9.1 Plates 9.10 - 9.11	NA*	Sign said car repairs. Storage of many chemical drums, most marked harmful	Likely, evidence of spillage on ground. Concrete cracked
D DD96/428	Figure 9.1 Plate 9.12	NA*	Disused/abandoned pig farm with chemical storage	Likely, cracked surface and spillage evident
E DD/96/2250	Figure 9.2	Storage of building materials	Storage of large metal containers. No access was allowed	Unknown. Further clarification of activities and any chemical storage required
F	Figure 9.2 Plates 9.13 - 9.14	Lard Boiling Factory	Metal Factory and storage area. Some oil drums noted	Possible, metal works are listed in ProPECC PN 3/94.
F, G DD96/645	Figure 9.2 Plates 9.15 - 9.16	NA*	Farm buildings, chemical storage, livestock waste drums, site generally littered with waste	Inventory of chemicals and pesticides used required. Rough surface may have allowed some infiltration
H DD96/702	Figure 9.2	NA*	Car repairs/dismantling yard - no access allowed	Likely but unknown. Probably hydrocarbon and heavy metal waste.
I DD96/704, 705, 709, 716	Figure 9.2 Plates 9.17 - 9.18	NA*	Container lorries parking, some storage of old chemical drums	Possible but identification of past spillages would be required.
J DD96/698, 699	Figure 9.2	NA*	Farm buildings. Some storage of chemicals and livestock feeds	Possible - further identification of chemicals and feeds required
K DD96/717, 718, 721	Figure 9.2 Plates 9.19 - 9.27	NA*	Rough surface, many chemical drums stored and spillage noted over cracked concrete. May be just outside works area but chemicals may also have been moved around site.Container storage area, some parked vehicles and drum storage	Initially determine if the chemical storage area falls within the works area. Contamination is likely at this point. Testing should also clarify whether the drums have previously contaminated any other area of the site.Possible, some containers are very old, and battered, spillages could have occurred.
L Gut Land	Figure 9.2	Permits for agricultural buildings and activities	Several pig farms	Possible - depending on chemicals used and stored.
M DD95/786, 791, 792, 722	Figure 9.3 Plate 9.28	Illegal container storage	Container and storage area with temporary structures. Surface rough and some chemicals stored	Possible - depending on whether any spillages have occurred.
N DD96/772	Figure 9.3 Plate 9.29	No registered landuse	Metal recycling company. Many parked vehicles, rough gravel surface.	Possible - depending on whether spillages have occurred
O (i) DD95/801	Figure 9.3	Sawmill and timberyard	No access to site	Unknown
O (ii) DD95/801	Figure 9.3	Sawmill and timberyard	Storage of timber. No chemical treatment is carried out on site	Unlikely.
P DD95/803	Figure 9.3	NA*	Storage area for adjacent factory.	Possible form historic contamination as this was a leather goods factory
R DD95/803	Figure 9.3 Plate 9.30	NA*	Car repairs/dismantling yard. Ground concreted and vegetated	Likely due to infiltration through cracked concrete and vegetation
S DD95/1994	Figure 9.3 Plate 9.31	Metal Works	Disused metal workshop, concrete surface	Unlikely due to concrete surface. But should not be dismissed as this is a ProPECC PN 3/94 defined activity.
T DD95/43-45, 53-59, 65-67, 70-74	Figure 9.3 Plate 9.32	NA*	Access denied but site is fenced and appears to be used as a repairs and maintenance site for Paul Y ITC	Likely but activities carried out here must be clarified
U DD96/717, 718, 721	Figure 9.2 Plates 9.19 - 9.27		Rough surface, many chemical drums stored and spillage noted over cracked concrete. May be just outside works area but chemicals may also have been moved around site.	Initially determine if the chemical storage area falls within the works area. Contamination is likely at this point. Testing should also clarify whether the drums have previously contaminated any other area of the site.

Note NA* - No information available from DLO

9.22 The main areas for concern are container storage areas, particularly those in DD99 close to Lok Ma Chau (A and B), the chemical storage area east of Pak Shek Au, (K), any car repair/dismantling yards and the unknown risks posed by the former leather factory (P and Q).

9.23 The main contaminants are likely to be oils, organic solvents and heavy metals. Some chemicals known to be hazardous were found. These included methylene chloride, listed as a hazardous air pollutant (under the US Clean Air Act, 1991). Many chloro alkanes are designated as priority pollutants (Clean Water Act) and are on the Superfund Hazardous substances list, as is chloroform which was found at site K. In addition to specific named substances and chemicals there was much evidence of oil and petrol spillage, piles of scrap metals and storage of unspecified chemicals.

Site Appraisal

9.24 From the desktop study and site visit information collected, it is possible to determine whether a contaminated land site investigation is needed. This information was used to check against the set of criteria described in Table 9.3 which is taken from the EPD Guidance Notes for Investigation and Remediation of Contaminated Sites of: Petrol Filling Stations, Boatyards or Car Repair/Dismantling Workshops. For this set of landuses if the answer to any of the criteria is 'No', a full scale site investigation is recommended. A positive answer to all criteria indicates that simplified site investigation may be sufficient. The criteria can be used as guidelines or indicators for different potentially contaminating landuses.

Table 9.3 Criteria for Adoption of Full-scale or Simplified Site Investigation

Criteria	Yes/No
1. Length of operation of the site is less than 5 years.
2. There is a practice of recording spill incidents or monitoring chemical storage.
3. Waste disposal is carried out in accordance with Government requirements
4. Absence of underground storage tank on site
5. Absence of surface contamination indicators which include: a) stained areas b) uncontrolled chemical drum storage c) cracked concrete near storage of chemical drums d) unnatural colours and odours; and e) abandoned piping/mechanical components or cans.

9.25 In the case of Spur Line, no site along the alignment is known to have an underground storage tank. At several sites where chemicals are stored, a negative answer is likely to criteria 2 and 3 as most sites landuse is illegal and no DLO records are available. At many of the sites there is evidence of spillage of chemicals, uncontrolled chemical drum storage, cracked concrete or rough gravel surfaces, all of which are criteria for full scale site investigations. On the basis of this information, a Land Contamination Assessment Plan (CAP) is recommended. The following section describes the CAP for the Spurline Project.

Land Contamination Assessment Plan (CAP)

9.26 This section summarises the results of the desktop study and site inspection and proposes a sampling and analysis programme based on the data collected. The sampling programme should be carried out during the site investigation stage.describes the approach to be taken in the development of the CAP. A detailed CAP showing the locations of the boreholes and defining depths to be sampled and parameters to be sampled, will be presented as a separate document to EPD for approval.

Site Investigations

9.27 A site investigation should be approached in a systematic way bearing in mind the purpose and the level of detail which is required. The main topics, as defined by EPD (1999) are:

· Physical site conditions, including geology, topography, soil type and physical properties, drainage and groundwater.

· Likely contaminants - previous site use.

· Extent and severity of contamination, the concentrations, depth, spatial distribution of contamination in both soils and groundwater.

· Effects on users, including the nature and level of contamination with regard to future use.

· Potential environmental harm.

· Hazards during construction.

9.28 The subsurface geology and groundwater flow are important as petroleum hydrocarbons in particular can float and migrate some distance. This could impact other drainage waters around the Spur Line alignment and cause modification of BOD_s5, SS and other important parameters. Many of the areas where potential contamination sites were identified, are located on flat, low-lying land, not far above the water table. There is therefore potential for contaminants to enter the groundwater in these areas.

9.29 Table 9.4 below lists the lot numbers and the main activities at each site identified. Likely contaminants associated with different site activities are listed in Table 9.5. The level of contamination and the extent of contamination need to be determined through a formal sampling and analysis programme and the most suitable methods for clean up of the site determined.

Table 9.4 Lots along the Spur Line and Potential Contaminating Landuses

Site	Fuelling Areas	Servicing /Parking Areas	Paint Shop	Fitting out/ repairs	Coating/ steel treatment	Vehicle Breaking	Chemicals or waste storage	Drainage and soakaway systems	Agricultural Activities	Unknown
A	√	√	√	√	√	√	√	√
B	√	√	√	√	√	√	√
C							√
D							√		√
E										√
F	√				√		√
G									√
H		√								√ Vehicle repairs etc likely
I		√		√			√
J									√
K							√
L									√
M		√	√	√		√	√
N		√					√
O (i)										√
O (ii)							√			√
P							√
R		√	√	√			√
S				√	√		√
T	√	√	√	√	√	√	√
U							√

Table 9.5

Activities found along the Spur Line and their likely associated contaminants

Contaminant	Fuelling Areas	Servicing/ Parking Areas	Paint Shop	Fitting out/repairs	Coating/steel treatment	Vehicle Breaking	Chemicals or waste storage	Drainage and soakaway systems	Agricultural Activities	Others
Metals (all)	√	√	√	√	√	√	√	√	√	√
Lead	√	√	√
Chromium		√
Zinc	√		√
Copper	√	√
Cyanides				√	√		√	√		√
Organic Contaminants		√	√	√	√		√	√	√	√
Simple aromatics	√	√		√	√	√	√			√
Organic solvents	√	√	√	√	√		√			√
Polyaromatic hydrocarbons		√			√	√	√			√
Fuels/oils	√	√		√		√	√	√	√	√
Biocides				√	√	√	√	√	√	√
Oily sludges		√		√	√	√	√	√	√	√
Microbacteriological							√	√	√	√
Acids				√	√	√	√	√

NOTE:

Simple aromatics includes benzene, toluene, ethylbenzene, xylene etc

Organic solvents includes non-halogenated and halogenated solvents

Fuels/oils includes Total Petroleum Hydrocarbons

Acids includes sulphuric and hydrochloric

SOURCE: EPD (1999)

Voelcker Science (1999)

Preliminary Methodology for Evaluation of Contaminated Land

Selection of sampling locations

9.30 From the desktop study and site visit information collected, the need for a contaminated land site investigation was determined. This information was used to identify areas of potentially contaminated land. The approach taken to be taken in the CAP in selecting suitable locations for sampling and analysis tookmust take into account the following factors:

• The extent to which the potentially contaminated land site overlapsped with the KCRC Scheme boundary.

• The form of the railway alignment at the location of each site (viaduct, cutting or embankment/at grade).

• The location of boreholes being conducted for the GeotechnicalSite Investigation (S.I.)as part of the site investigation works.

9.31 The sections of each potentially contaminated land site which fall within the Spur Line Scheme Boundary are shown on Figures 9.4 –1 to 9.6-3 and tabulated in Table 9.6. The figures also show the limits of the viaduct, cutting and embankment sections along the alignment. The locations of those boreholes that are within the potentially contaminated sites and will be used for sampling and analysis under the Contaminated Action Plan (Stage 1) are highlighted. These boreholes have been located to coincide as far as possible with the locations of identified “hotspots” during site visits.Boreholes which are defined as part of the SI should be located, as far as possible, at “hotspot” locations defined in the CAP. These “hotspots” are generally locations where staining has been noted from vehicles, chemical storage areas, or spillage.

9.32 Also included on the drawings are other boreholes from which samples will be taken and retained at the same time as sampling from Stage 1 boreholes. These samples will only be tested if the Stage 1 samples indicate contamination. Figures 9.7 to 9.187. Show further details of monitoring locations for Stage 2 of the CAP investigation, if samples from Stage 1 are found to be contaminated according to the Dutch List criteria. These figures show the grid locations for sampling under Stage 2 of the CAP, and locations for sampling in the viaduct sections of the railway alignment. Where these locations are within buildings (such as in farm sites), no samples will be taken unless analysis of locations outside the buildings have been taken and are shown to be contaminated. The number of boreholes and/or trial pits needs to be defined in the CAP and approved by EPD as part of the Stage 1 sampling. If samples from these locations are contaminated according to the Duch hint criteria (Appendix K), Stage 2 sampling is required. Stage 2 sampling takes the form of grid sampling according to ProPECC PN 3/94.

9.33 Where the sites are beneath a viaduct section of the railway, samples will should be taken from boreholes close to the proposed pilecaps. If further testing is required, this will be limited to the pilecap locations as shown on Figures 9.7 to 9.187. The remainder of the area around the pilecap will not be excavated and will therefore not require investigation. and other areas where significant ground disturbance or excavation may occur. If changes are made to the interface of the viaduct/cutting or viaduct/embankment sections during the detailed design stage, the principles described in this section regarding number and location of samples in each type of railway section should be followed.

9.34 Where no boreholes are available for sampling close to the potentially contaminated site, a trial pit willshould be dug within the site of interest at a suitable “hotspot”. In some cases, access could not be gained during the site visits and the location of the trial pit will need to be defined when the land has been resumedaccess has been obtained.

Sampling methodology

9.35 Prior to a borehole being constructed, it is usual practice to dig an inspection pit up to 3m deep to verify the presence or absence of utilities. An environmental scientist with experience in contaminated land assessment should be on site to monitor the first few boreholes to confirm that the samples are being taken at the right locations and in the correct manner. A visual inspection of the trial pits will also enable the environmental scientist to make a visual assessment of the likelihood of severe contamination.

9.36 It is preferable that samples are taken from the trial pit as a visual assessment of the ground material can be made more readily than a borehole and the exact sample depth can be verified. If contamination is suspected at the base of the trial pit, samples willshould be taken at a greater depth from the borehole. In locations where there are several boreholes being dug for geotechnical investigations, but only selected boreholes have been chosen at the “hotspots” for Stage 1 contamination assessment, samples will also be taken from the other boreholes at similar depths, and retained in cool conditions (at 4^oC) until results have been obtained for the initial “hotspot” samples.

9.37 Table 9.6 describesThe CAP should describe the locations and number of boreholes and trial pits to be sampled, the number of samples to take and the parameters to be tested. From site visits, it is likely that In all cases, Total Petroleum Hydrocarbons (TPHs) will be analysed in all cases. In selected samples, metals, cyanide and organics (chlorinated and non-chlorinated solvents, aromatics and polyaromatic hydrocarbons (PAHs)) will be included in Stage 1 sampling. In sites such as container yards, organics are unlikely less likely to be a problem. and are therefore not included in the parameter list. However, in chemical storage sites organics are one of the main potential contaminants. The result of these analyses will help to fine tune the testing required for Stage 2 sampling and analysis.

9.38 At Stage 2, additional samples should be taken in the same area if the potential “hot spot” samples are shown to be contaminated. These additional samples will be taken on a grid sample basis as outlined in ProPECC PN 3/94 and the Contaminated Sites Investigation Remediation Guidance Notes. The locations covered by the grid at the potentially contaminated sites will be shown in the CAP.

Table 9.7

Grid Sampling to be Conducted if “Hot-spot” Sample Indicates

the Presence of Contamination

9.39 The proposed analysis programme is summarised below:

Two Stage Analysis Programme

Sampling methods

9.40 There are several methods that can be used to obtain samples of potentially contaminated material within the ground. These are listed below:

· Hand methods - usually for depths up to 0.5m by manual excavation or up to 5m with a hand auger. This usually produces only small, disturbed samples.

· Trial pits - can be used up to about 53m depth. Allows easy collection of large samples.

· Light cable percussion boreholes - traditional method for geotechnical soil investigations. Can penetrate to 50m depth and allow easy water monitoring or gas wells to be inserted.

· Power auger drilling - very quick method, however samples are limited to around 6 m depth and are disturbed.

9.41 Trial pits are the most widely used technique, especially when sampling is required to depths of less than 3m. Care should be taken to avoid underground services. It is likely that a combination of boreholes and trial pits can be used for the Spurline iInvestigations.

9.42 For borehole sampling, samples will be collected from the top, middle and bottom (above rockhead) of the borehole as recommended in BSI DD175. The depth of the samples will depend on the field sampling data. For trial pit sampling, samples will be taken at three depths (e.g. 0.5m, 1.5m and 3m). If contamination is evident at 3 m depth, additional samples at greater depths should be collected. Where groundwater is encountered, groundwater samples should also be taken and records kept of the ground water level in the trial pit. Photographic records should be kept of each borehole and trial pit to show the gradient of pollution into the ground and the appearance of each sample. The presence of any free product floating on the top of the groundwater and the thickness should be recorded. The floating layer should be removed/recovered and analyzed.

9.43 All soil samples should weigh not less than 0.5 kg and must be representative of the location at which they are taken. Samples should be handled in an appropriate manner so as to avoid cross contamination, and should be stored between 0 - 4ºC. Cooling of samples containing volatile contaminants is especially important. All samples should be properly labelled and any excess sample kept for further testing if necessary. Sample containers should be thoroughly cleaned between sampling of individual samples. It is important for the sampling person to avoid direct or indirect contact with potentially contaminated materials.

9.44 All samples should be well contained, sealed, properly labelled and any excess sample kept for further testing if necessary.

Parameters to be Tested for Contamination

9.45 The parameters to be tested at each proposed sampling location are shall be based on the expected contaminants related to the land use. Prior to sampling, an examination of the site should be made by an environmental scientist responsible for the sampling, to confirm whether additional or alternative analyses are required apart from those listed in Table 9.6to those listed in the CAP.

9.46 Waste automotive oils which may be detected at container sites are composed of an organic base with additives to increase performance. Additional compounds such as chlorinated solvents may be present in the waste oils due to blending of used oils during storage. The presence of such suspected carcinogens and mutagens is the basis of concern about waste oils in the environment. The sampling programme recommends that in Step 1 only total petroleum hydrocarbons (TPH) are tested for as recommended in ProPECC PN 3/94 (Appendix III). If necessary, Polyaromatic hydrocarbons (PAHs) and Benzene, Toluene, Ethylbenzene and Xylene (BTEX) will be required to be determined if Step 2 of the analysis programme is to be implemented.

9.47 For the inorganic analysis heavy metals (including Cd, Cr, Cu, Hg, Ni, Pb and, Zn etc) should be determined in addition to cyanides and sulphates.

Analytical Laboratory and Methodology

9.48 The laboratory for chemical analysis for the land contamination assessment should achieve HOKLAS accreditation for environmental testing of sediment trace metals: Cd, Cr, Cu, Ni, Pb, Zn and Hg and preferably for TPH, PAHs and BTEX.

9.49 The methodology should be compatible with international standard methods. Detection limits should be to standards listed in Table 9.8.

Table 9.8

Detection Limits of Parameters to be analysed

GroupNo.	Parameter	Detection Limit (mg/kg dry soil)
1	Metals: Cd, Cr Cu Hg Ni Pb Zn	0.2 20 10 0.1 10 10 40
2	Total Petroleum Hydrocarbons (TPH)	20
3	Benzene Toluene Ethylbenzene Xylene	0.002 0.01 0.01 0.01
4	Polyaromatic Hydrocarbons (PAH)	0.2

9.50 The preliminary sampling number and locations will be reviewed and a detailed land contamination assessment plan will be submitted for approval by the Director in accordance with the requirements set out in the ProPECC Practice Note 3/94 “Contaminated Land Assessment and Remediation” prior to on-site assessment before commencement of works.

Evaluation of Potential Impacts

9.51 The interpretation of analytical results should be considered by comparing the data with the Dutch Indicative List which is recommended by EPD in ProPECC PN 3/94 for interpretation of the analytical results.

9.52 The soils, geology, groundwater and climate of Hong Kong are different to those of the Netherlands. The reference values have been developed for use under these specific conditions. The adsorption of pollutants to soil colloids may be different under such conditions and therefore pose a different toxicity risk.

9.53 Appendix K contains the Dutch list which should be considered carefully in terms of application to the Hong Kong environment. It can be used as an indicative measure of levels of contamination, qualitatively based on like groups of contaminants, known landuses and possible pollutants.

Remediation Measures to be Considered in the Remediation Action Plan (RAP)

9.54 Following approval of the CAP by EPD and completion of the sampling and analysis programme, a Contaminated Assessment Report (CAR) will be produced. The CAR will detail the results of the implementation of the CAP and evaluate the extent of the potential contamination on the site. Suitable means of minimizing the environmental impact from these areas of contamination should be defined. If remediation of the land is required, the type of remediation should be identified in a Remediation Action Plan (RAP).

9.55 The selection of an appropriate remediation technique for a site is dependent on a number of factors including:

(i) the type of contamination;

(ii) the extent of contamination;

(iii) the time available and speed of each technique;

(iv) cost effectiveness;

(v) the future use of the site;

(vi) availability of expertise and equipment.

9.56 There are a range of options available for treating contaminated land sites and new techniques are constantly being developed. The main methods in use are:

· Retention and isolation of material on-site using an appropriate form of cover, barrier or encapsulation system.

· Physical, chemical or biological treatment to eliminate or immobilise the contaminants.

· Removal of material from the site for disposal elsewhere.

9.57 ProPECC Note PN 3/94 also includes recovery trenches or wells for removal of leaked oil and soil venting for volatile organic compounds (VOCs). It suggests that "wherever possible, in-situ remedial measures should be adopted". This policy should be followed as far as possible in order to prevent increasing the pressure on landfills.

9.58 Table 9.9 describes several techniques which would may be applicable to contamination expected within the works of the Spur Line.

Table 9.9

Remediation techniques which could be used at sites along the Spur Line

Type of Contamination	Technique
Oil - surface layers	Bioremediation - in-situ or on site degradation of organic pollutants to harmless CO2 & water using microbes. Ranked I by Haiges (1989). Other bioremediation techniques include adding cotton which absorbs the oils. Bacteria which occur naturally in the cotton then degrades the oils before decomposing the cotton into the soil and enriching it. Soil washing/flushing – addition of a surfactant/solvent and flushing in-situ or washing excavated soil. The oils and fluids separate out and the oily waste can then be bioremediated.
Oil - above groundwater or at depth in the soil.	Recovery trenches or wells – used to constrain groundwater flow so that oils settle and can be skimmed off. A dual pump system uses a deep pump in the groundwater to create a depression cone into which the free floating product will migrate. This can then be pumped off. The dual pump system is ranked I by Haiges. Other techniques include simpler pumps which extract both oils and water which can then be separated at the surface..
Heavy hydrocarbons and oily sludges	Thermal treatment - soil is excavated, sorted and fed into a rotary kiln thermal unit and heated until combustion occurs. The clean soil is then cooled and moistened and can be replaced.
Cyanides	Incineration – similar thermal heating and combustion as for heavy hydrocarbons. Care must be taken to ensure that air emissions achieve required standards.
Heavy Metals	Soil washing – soil is passed through sieves and scrubbers using water or oxidising chemicals which leach the contaminants out. The sludge residue can then be disposed of at a chemical waste treatment plant. Discharge of wasthed water must comply with WPCO standards. Stabilisation – contamination can be permanently isolated using lime, cement, thermoplastic or soluble silicate reagents to chelate metal ions to soil colloids. The soil is excavated, sorted and injected with the reagent before replacing and compacting to high density.
Volatile Compounds	Soil Venting – contaminant are removed through extraction wells using a vacuum which enhances chemical movement from soil particles to air pockets. Air Sparging – mainly used to remove volatiles from groundwater by injecting air into the saturated zone and transferring the contaminants to the vadose zone from which they can be vented.
Microbiological	Incineration – to eliminate any toxic micro-organisms or bacterias, such as anthrax spores, the only consistently dependable method is incineration.
Broad spectrum of contaminants	Excavation and Landfilling – best used for shallow contaminants and one off excavations. Because of limits on contaminants that can be disposed of in landfills (based on TCLP)* pre treatment may be required by another method (e.g. bioremediation) prior to disposal.

NOTE:

Haiges (1989) rated techniques from 1 (best) to 8 (worst) for treatment of oil contaminated soils on the basis of technical feasibility, achievable treatment levels, adverse impacts, cost and time taken.

* TCLP - Toxicity Characteristic Leaching Procedure Limits - as outlined in the Guidance notes issued by EPD (1999).

Application of Contamination Action Plan to Spur Line

9.59 From the desktop study, site survey and generic methodology for sampling and analysing pollutants from potentially contaminated sites, a number of sites along the Spur Line alignment have been identified as being potentially contaminated.

9.60 Prior to the completion of the CAP and CAR, an estimate has been made of the quantity of contaminated land which may be present at each site (Table 9.10). This is based on site visits, the extent of the area used at each site, and the assumption that the contamination has penetrated to a depth of approximately 1 m from the ground surface. Where viaduct occurs, it is assumed that only the area around the viaduct support footing pile cap will be impacted during construction (each footing pile cap is assumed to be 2.56.0 m diameter with an additional 2.0 m allowed for the works area.) HoweverIn the embankment and cutting sections, the whole width of the viaduct (32 m) may be impacted and has therefore been included in the calculation. Where quantities of material are too small to make physico-chemical or biological treatment cost-effective, disposal of the material may be considered.

9.61 The total quantity of contaminated land is estimated at this stage of the assessment, to be up to 5635,000 m³. This volume needs to be confirmed through implementation of the CAP and the sampling and analysis programme during site investigation, at which time the quantities requiring remediation or disposal will be more accurately defined.

9.62 Where volumes are relatively small and/or contaminant level is low, disposal may be a preferable option. Where volumes are large and/or contaminant levels are high, remediation techniques should be considered as a cost effective and environmentally favourable option.

Table 9.10 Main Activities at Each Site, Contaminants Likely to be

Present and Possible Extent of Contamination

Site	Main Activities	Estimated quantity (m³)	Main Contaminants Likely to be present
A	Container Storage	8 and EVA = 80700 m³	Metals, organics, fuels/oils, acids, cyanides
B	Container Storage	13,00011,000 m³	Metals, organics, fuels/oils, acids, cyanides
C	Chemical Store	1,7000 m³	Organics, oils, metals, solvents
D	Pig Farm	5600 m³	Organics, mMetals, microbacteriological
E	Building Materials Storage	200 m³	Metals
F, GF	Farm BuildingsMetal factory	5000 m³<100 m³	Organics, mMetals, microbiologicalMetals, organics
HG	Car Repairs/ dismantlingFarm Buildings	300 m³5000 m³	Metals, cyanides, organics, fuels/oils, acidsOrganics, metals, microbiological
IH	ContainersCar Repairs/ dismantling	2000 m³<300 m³	Metals, organics, fuels/oils, acids, cyanidesMetals, cyanides, organics, fuels/oils, acids
JI	Farm BuildingsContainers	1000 m³2000 m³	Organics,M metals, microbiological contaminationMetals, organics, fuels/oils, acids, cyanides
KJ	Chemical StorageFarm Buildings	1300 m³1000 m³	Organics, solvents, metals, oilsOrganics, metals, microbiological contamination
K L	Pig FarmsChemical Storage	10000 m³1300 m³	Organics, mMetals, microbiological contamationOrganics, solvents, metals, oils
ML	Container StoragePig Farms	100 m³10000 m³	Metals, organics, fuels/oils, acids, cyanidesOrganics, metals, microbiological contamation
NM	Metal RecyclingContainer Storage	-2000 m³	Metals, TPH organics (oils)Metals, organics, fuels/oils, acids, cyanides
O (i)N	Sawmill and TimberyardMetal Recycling	<100 m³300 m³	Unknown activitiesMetals, organics (oils)
O(ii)O (i)	Sawmill and TimberyardSawmill and Timberyard	100 m³500 m³	OrganicsUnknown activitiesUnknown activities
PO(ii)	StorageSawmill and Timberyard	-2000 m³	Organics, solvents, metals, oils, bacteria sporesOrganics
RP	Car Repairs/ dismantlingStorage	-300 m³	Metals, cyanides, organics, fuels/oils, acidsOrganics, solvents, metals, oils, bacteria spores
SQ	Metal WorksBag Factory	-<100 m³	Metals, organics, solventsOrganics, solvents, metals, oils, bacteria
TR	Vehicle MaintenanceCar Repairs/ dismantling	300 m³600 m³	Metals, cyanides, organics, fuels/oils, acidsMetals, cyanides, organics, fuels/oils, acids
US	Chemical StorageMetal Works	1500 m³200 m³	Metals, oOrganics, solvents, atMetals, organics, solvents
Total volume (m³)		5635,0200 m³

Precautionary Measures to be taken during Construction

9.63 The following measures should be implemented to minimise risks to workers during remediation works, excavation of soil, construction of viaducts, blasting of the cutting, piling works or construction of the stations. These measures will also mitigate against transferring contamination to groundwater, to surface water courses or to the air.

· Site workers should wear gloves, masks, and other protective clothing where exposure to vapours or contaminated soil may be encountered.

· Contaminated materials should be moved with bulk earth movers to prevent human contact.

· Adequate washing facilities should be provided and smoking/eating should be prohibited in the area.

· Contaminated sediments which have been stockpiled or are being transported should be covered with tarpaulin.

· Leakage of pollutants or leaching from excavated soil should be prevented by storing on an impermeable surface.

Temporary Works Areas

9.64 There are several temporary works areas in the Sheung Shui area which have previously been used as container parking areas. The site inspection showed that, as is typical of such landuses there has been some leakage of oils and lubricants. However, these sites should not pose a health risk during their use in the construction phase provided there are no earth moving activities at the sites. The leaked oil can be covered with a layer of gravel or sawdust to soak up the leaks, and the materials disposed of appropriately.

Other Projects in the Study Area

9.65 The recently publicized Kwu Tung SGA under the NENT Planning Study also has the potential to be impacted by contaminated land. The findings and recommendations of the Spur Line EIA should be taken into account in the EIA for the SGA, to minimize environmental impacts.

Summary

9.66 This contaminated land assessment includes a desktop study on relevant past and present landuses, a site survey, an assessment on the findings and recommendations on a schedule ofof the approach to the sampling / analysis of essential parameters and appropriate remediation measures. Application of the sampling/analysis programme to specific sites identified to have potential contamination along the Spur Line alignment is included. A Contaminated Land Assessment Plan (CAP) will be submitted separately to EPD for approval. This will outline the methods for sampling and analysis of the identified potentially contaminated sites, and criteria for evaluation.

9.67 No underground storage tanks or extensive areas of contaminated land have been identified in this assessment within the works area of the alignment. The main areas for concern are container storage areas, particularly those in DD99 close to Lok Ma Chau (A and B), the chemical storage area east of Pak Shek Au, (K), any car repair/dismantling yards and the unknown risks posed by the former leather factory (P and Q). The main contaminants are likely to be oils, organic solvents and heavy metals.

9.68 Remediation measures for different types of potentially contaminated land are recommended, however, the small quantities which have been identified for several sections of the alignment make remediation too costly to be effective, and disposal should be considered. It is estimated that the quantity of material in areas of potential contamination, which requires treatment or disposal is approximately 535,000 m³. These quantities and the degree of contamination need to be confirmed at the site investigation stage. Following the implementation of the approved CAP, a Contamination Assessment Report (CAR) and Remediation Action Plan (RAP) will be prepared to recommend the methods of remediation or disposal to be followed. This assessment indicates that potentially contaminated material excavated during the construction of the alignment, does not present an insurmountable environmental impact to the Project.

REFERENCES

Holdgate, M.W., (1979) A Perspective of Environmental Pollution, University Press, Cambridge.

Royal Commission on Environmental Pollution (RCEP), (1984), 10th Report: Tackling Pollution - Experience and Prospects, Cmnd 9194, HMSO, London.

LaGrega M.D., Buckingham P.L & Evans J.C. (1994), Hazardous Waste Management, McGraw-Hill, Singapore.

Cairney T (ed) (1993), Contaminated Land: Problems and Solutions, Chapman & Hall, London.

EPD (!999), Guidance Notes for Investigation and Remediation of Contaminated Sites of: Petrol Filling Stations, Boatyards or Car Repair/Dismantling Workshops. Report EPD/TR1/99

Voelcker Science (1999) Guide to Contamination Packages

HSE (1998), Protection of Workers and the General Public during Development of Contaminated Land.

http://www.ContaminatedLAND.co.uk/ - Pages on Past Industrial uses, Causes of Contamination, Standards and Guidelines, Remediation Techniques

British Standards Institution (1988), Draft for Development DD175: 1988 Code of Practice for the Identification of Potentially Contaminated Land and its Investigation, BSI, London.

Kelly R.T. (1980) Site Investigation and Material Problems, in: Reclamation of Contaminated Land, B21-B2-13, Society of Chemical Industry.

Haiges L et al. (1989) Evaluation of underground fuel spill clean-up technologies, in Haztech International Conference, San Francisco.

ProPECC PN 3/94. Environmental Protection Department. Practice Note for Professional Persons: Contaminated Land Assessment and Remediation.