9. Land Contamination and Ground Conditions

Transcription

1 9. Land Contamination and Ground Conditions 9.1 Executive Summary The site is located upon an area that has historically been utilised for opencast quarrying and was subsequently backfilled with quarry waste material. It is therefore considered that the development is located on brownfield land which could have a potential contaminative legacy. The drift geology map identifies the site as underlain by man-made deposits of waste and or natural earth materials filling a former opencast excavation. The surrounding area is of glacial meltwater deposits comprising of moundy deposits of sand and fine to course grained gravel, with deposits of laminated silt and clay. It is likely that these deposits would have underlain the site prior to the opencast excavations and may have been used as fill material. The solid geology underlying the site comprises the Lower Limestone Group of sandstone, siltstone, mudstone and limestone contained within the Carboniferous Limestone Series. To prove the underlying ground conditions at the site an Intrusive Site Investigation was undertaken by Waterside Environmental, supervised by RPS. This included the completion of a number of boreholes, soil gas and groundwater monitoring installations. During the investigation analytical testing and site monitoring was carried out to provide data on the geology, the chemical condition of the site soils and the level of soil gases present underlying the site. The results of the site investigation revealed that there is a limited impact to site soils. None of the results exceeded the soil guideline values (SGV) or generic assessment criteria (GAC) for a Commercial and Industrial land use scenario. Gas monitoring carried out at the site on four occasions has revealed no presence of methane gas and only slightly elevated concentrations of carbon dioxide, maximum concentration of 4.3% recorded in borehole T3 (see Appendix 12 of Interpretative Site Investigation Report for location of boreholes) on the second round of monitoring. Where any impacts are evident these are typically associated with the made ground and are present at relatively minor levels. These are not considered likely to present any significant implications on the future land use at the Facility site. The assessment identified a number of potential impacts that may be associated with the construction and operation of the Facility. The impacts identified can be mitigated to levels considered to be of negligible significance through the implementation of construction management practices or readily practiced engineering design principles. 9.2 Introduction The proposed location of the Facility is upon a site historically utilised for opencast quarrying. This has subsequently been back-filled with quarry waste material. Consequently, land upon which the development is planned should be regarded as brownfield land with a potential contaminative legacy. In order to ensure the environmentally sound development of the site this Chapter details the existing baseline conditions at the site and assesses the potential for these to be adversely 180

2 impacted by the development. This enables any appropriate mitigation measures to be identified as necessary. This Chapter assesses the potential impacts associated with the Facility on the surrounding geological conditions taking due account of contaminated land considerations. During the construction stage existing geological and contaminative conditions will be assessed and considered in the engineering design of the development. The ground conditions at the site have been summarised using available published records and site reports, to determine the baseline conditions and potential constraints of the proposed development. 9.3 Methodology To establish the baseline information for the site the following sources of information were gathered or completed: desk study information; site walkover; and intrusive investigation. Further details of information used in the determination of the baseline study are included in the sections below. In order to carry out the Environmental Assessment for the Land Contamination and Ground Conditions the following was undertaken: consultation with relevant statutory and non-statutory organisations to obtain information on key elements that these parties would require to be considered within the assessment; assessment of the significance of potential impacts that the proposed development could have on present site conditions and their surroundings based upon sensitivity, severity, risk and likelihood and in line with the principles advocated in Part IIA of the Environmental Protection Act 1990 and CIRIA guidance C552; and recommendations of mitigation measures to reduce impacts to acceptable levels and the identification of any residual impacts and their significance, (as required). Further details of how the Assessment was carried out are detailed in the sections below. Legislative Background This assessment has been conducted in consideration of the principles of Part IIA of The Environmental Protection Act 1990, amended by the Contaminated Land (Scotland) Regulations 2005 in light of the Water Environment and Water Services (Scotland) Act

3 Further guidance literature considered during the assessment is summarised below: TABLE 9.1 GUIDANCE LITERATURE Format Reference Legislation Control of Pollution Act (As Amended) 1974; and Environmental Protection Act 1990: Part IIA Contaminated Land Statutory Guidance (Edition 2, Scottish Executive May 2006). Statutory The Contaminated Land (Scotland) Regulations Instruments SEPA Policies No.54 Land Protection Policy. SEPA Pollution PPG2: Above ground storage tanks; Prevention PPG3: Use and design of oil separators in surface water drainage Guidelines (PPGs) systems; PPG6: Working at construction and demolition sites; PPG8: Safe storage and disposal of used oil; PPG11: Preventing pollution at industrial sites; and PPG21: Pollution incident response planning. Scottish Executive PAN 33 Development of Contaminated Land; Planning Advice PAN 51 Planning and Environmental Protection; and Notes (PANs) PAN 58 Environmental Impact Assessment. National Planning NPPG 10 Planning and Waste Management; and Policy and NPPG 6 Renewable Energy Developments. Guidelines Other Guidelines Protection of Workers and the General Public during the Development of Contaminated Land (HSE 19991); CLR 11: Model Procedures for the Management of Land Contamination (Environment Agency 2004); and CIRIA 552: Contaminated Land Risk Assessment A Guide to Good Practice (CIRIA 2001). CIRIA Environmental Good Practice on Site The principles that underlie the assessment of the potential impacts associated with contaminated land are documented in Part IIA of the Environmental Protection Act 1990 and advocate an approach based around source-pathway-receptor assessment. If each of these elements is present (i.e. a source, a pathway and a receptor) then a pollutant linkage exists that may pose a risk to the environment. Typically the presence of pollutant linkages is assessed in the form of a Conceptual Site Model (CSM) that highlights connections between sources and receptors by potential pathways. If a pollutant linkage exists the severity of the impact posed by this linkage, or risk, needs to be assessed to establish the level of significance of the potential impact, and hence whether any remedial actions are required to mitigate the impact. It is this same approach that can be adopted in the assessment of potential impacts to the environment as part of this ES. In the application of this approach the assessment considered the following: potential sources including historically impacted soils located on site or potential elements of the construction and operational phases of the development that may generate impacts (e.g. fuel storage areas); potential pathways including various forms of contact with humans (e.g. ingestion of soils), runoff of contaminants to soils, migration of soil gases to neighbouring properties; and Potential receptors including human health (e.g. neighbouring properties), the water environment, property or ecological sites (e.g. SSSIs). 182

4 It is important to consider wider receptors (e.g. the water environment) in the assessment of contamination and ground conditions as the interaction between these elements in the conceptualisation of the site is complex and one can define the nature or behaviour of the other. Consultation As part of the consultation process carried out in the Scoping Report the following relevant authorities were contacted in relation to the site and to comment on the proposed methodology for completion of the assessment. British Geological Society (BGS); and SEPA. Responses from the above authorities have outlined that due to the past quarrying activities and adjacent landfill, the BGS did not have any reason to make comment on the development or proposed methodology. In addition SEPA made no comment on the proposed methodology of the Land Contamination and Ground Conditions Chapter. Desk Study Information and Walkover In order to determine the baseline conditions at the Facility site, a desk study and site walkover were undertaken. When data gathered during this exercise was combined with more site specific information gathered during intrusive investigation works, this allowed the development of the conceptual site model, highlighting potential pollutant linkages and those that should be considered for significance. The desk based research undertaken has gathered information from the following sources: geological and hydrogeological plans; historical maps; Landmark Envirocheck Report, ref: _1_1; information available from local and regulatory authorities, including SEPA; and British Geological Survey (BGS) records. After an initial review of the available desk based information for the Facility site, a site walkover was undertaken. This exercise determined the current site conditions, surrounding conditions, and allowed for a visual inspection of areas of interest identified during the desk research, such as: current site use including potential sources of contamination; topography of site and surrounding area; visual/olfactory evidence of potential contamination; details of surrounding land use; and location of nearest watercourse. Intrusive Investigation In order to investigate geological conditions, and given the potentially contaminative historical land use at the site and the proposed development, intrusive investigations were undertaken based upon information compiled in the desk study. These 183

5 provided details on the site-specific conditions allowing for a more accurate interpretation of the potential pollutant linkages in the conceptualisation of the Facility site. Intrusive site investigations were undertaken by Waterside Environmental, supervised by RPS. This included the completion of a number of boreholes, soil gas and groundwater monitoring installations. Specific details regarding the findings of these investigations are provided in the following interpretative report presented in Appendix 9: Interpretative Site Investigation Report, September 2007, RPS. The intrusive investigation works, analytical testing and site monitoring provided data on the geology, the chemical condition of the site soils and the level of soil gases present underlying the site. Where appropriate, this information has been used in the interpretation of the site conditions as discussed below. Impact Assessment The following process was undertaken to assess the significance of potential environmental impacts that may arise as a result of the construction and operation of the development: Defining the Sensitivity of Receptors (Baseline) utilising information collated in the desk research and the intrusive site investigations to identify the condition of the site and its surroundings; Establishing Potential Sources (Potential Impacts) based on information made available regarding the nature of the project, determine the likely activities or form of development relating to the construction, operational and decommissioning phases of the project and considering historic activity at the site; Determining Pathways (Potential Impacts) consider how the above activities may impact receptors based upon conceptualisation of the site defining complete source, pathway and receptor linkages; Assessing the Impacts determine the significance of potential impacts based upon the process outline below in Diagram 9.1, in the context of the conceptualisation of the Facility site; Specifying Mitigation Measures identify any appropriate mitigation measures to eliminate, or reduce the significance of the potential impacts; and Reassessing the Impacts determine the residual significance of likely residual impacts based upon the process outline below. The significance of the potential environmental impacts was evaluated taking into account the following factors: receptor sensitivity; impact severity; consequence risk; and 184

6 likelihood, both before and after mitigation. The predicted severity of potential impacts is compared with the sensitivity of receptors in order to assess the level of risk posed by the consequence of that impact using the Sensitivity verses Severity Matrix, shown in Table 9.2. The risk is then compared against the likelihood of the impact occurring to determine the significance of the impact, as outlined in the Risk verses Likelihood Matrix, shown in Table 9.3. ly, the significance of the impacts can be re-assessed considering the likelihood that reflects any mitigation measures to be employed. This defines the residual significance of any potential impacts associated with the proposed construction, operation and decommissioning phases of the project. This complete process is outlined in Diagram 9.1. The structure and definitions used in the assessment process outlined below have been influenced by the processes specified for the classification of contaminated land as detailed in CIRIA guidance document, CIRIA 552: Contaminated Land Risk Assessment A Guide to Good Practice, These have been combined with forms of EIA significance assessment more widely used throughout consultancy to consider the sensitivity of the receiving environment. Those impacts identified with a significance of Moderate or Major should be regarded as Significant under the EIA Regulations. The Conceptual Site Model is presented in Figure 9.1. This highlights potential pollutant linkages present at the Facility site given the identified receptors and potential sources and pathways. It should be noted that Diagram 9.1 highlights a variety of receptors, such as human health, property and the water environment. Whilst the ground conditions form the focus of this Chapter, these other elements (e.g. the water environment) have been highlighted as they contribute to the consideration of the nature of the ground conditions. For example, should shallow groundwater (if present) be contaminated and require dewatering this may result in a greater impact upon the underlying soil conditions at the site by disturbance of contaminants within the groundwater. 185

7 DIAGRAM 9.1 SUMMARY OF PROCESS TO IDENTIFY SIGNIFICANCE OF IMPACTS Impact Severity Receptor Sensitivity Negligible Marginally Sensitive Pathway between source and receptor likely to be incomplete for linkage to either human health, water environment, property or ecological receptors. Low Human Health risk of chronic damage to human health but contamination isolated. Water Environment risk to water receptors through soil leaching. Property localised impact upon the fabric of existing properties. Ecology localised impact restricted to the confines of the site, likely to have minimal change upon a receptor. Medium Human Health risk of chronic damage to human health by widespread contamination. Water Environment impact upon surface water or ground water within the confines of the site. Property localised impact upon existing natural property (e.g. crops) or catastrophic upon the fabric of existing properties. Ecology a significant change or short term risk to an ecosystem (or part thereof) within the confines of the site. High Human Health risk of acute damage to human health irrespective of contamination distribution. Water Environment impact upon surface water or ground water within and beyond the confines of the site. Property catastrophic impact upon existing natural property (e.g. crops). Human Health no permanent existing human health receptors on or in vicinity of site, but potential temporary receptors. Water Environment no, or poor quality water receptors underlying or in vicinity of site. Property no existing properties on or in vicinity of site. Ecology no designated sites on or in vicinity of site. Sensitive Human Health existing human health receptors on or in vicinity of site but these are restricted to commercial/industrial land uses. Water Environment water receptors underlying site or in vicinity of site but likely to be of low, or potentially low, use. Property existing properties in vicinity of site. Ecology designated sites of regional importance on or in vicinity of site. Very Sensitive Human Health existing human health receptors on or in vicinity of site but these include residential or sensitive land uses (e.g. schools). Water Environment water receptors underlying site or in vicinity of site likely to be, or potential be, of high use. Property existing properties on or in vicinity of site. Ecology designated sites of international or national importance on or in vicinity of site. Ecology a significant change or short term risk to an ecosystem (or part thereof) within and beyond the confines of the site. Compare Magnitude and Sensitivity using Matrix in Table

8 Risk No Risk There are no risks to receptors, either as human health, the water environment, property of ecology. Minor Human Health risk of chronic damage to commercial/industrial human health receptors. Water Environment risk to water receptors, albeit of low use value, through soil leaching. Property localised impact upon properties in vicinity of site. Ecology localised impact upon designated site of regional importance on site. Moderate Human Health risk of chronic damage to human health either by isolated or widespread impact, irrespective of land use. Water Environment risk of impact by leaching or direct impact upon water receptors, irrespective of level, or potential level, of receptor use, but confined to site. Property localised impact upon natural property or catastrophic upon properties, on or off site. Likelihood Unlikely There is a pollutant linkage but circumstances are such that it is improbable that an event would occur even in the long term. Possible There is a pollution linkage and circumstances are possible under which an event could occur. However, it is by no means certain that even over a longer period such event would take place, and is less likely in the shorter term. Likely There is a pollution linkage and all the elements are present and in the right place, which means that it is probable that an event will occur. Circumstances are such that an event is not inevitable, but possible or likely in the short or long term depending on the nature of the impact. Ecology impact upon an ecological receptor, regardless of designation or impact scale. Major Human Health risk of acute damage to residential human health, or other sensitive land uses, (e.g. schools). Water Environment impact upon surface water or ground water beyond the site boundary with a high use value, or potentially high use value. Property catastrophic impact upon existing natural property (e.g. crops), regardless of location. Ecology a significant change or short term risk to an ecosystem (or part thereof) of national or international importance, regardless of site boundaries. Compare Risk and Likelihood using Matrix in Table 9.3 to define Significance. 187

9 Negligible There is a possibility that an event could occur, however in this instance it is considered that there is no risk posed to receptors. Minor The probability of the event occurring may vary. If the event were unlikely, its consequences would represent a major risk to potential receptors, but if the event were likely the risks to potential receptors would only be considered as minor. If the event were possible, the risks would be considered as minor to moderate. Moderate The probability of the event occurring may vary. If an event were possible, its consequences would represent a major risk to potential receptors, but if the event were likely the risks to potential receptors would only be considered as moderate. Major There is a definite risk to receptors. This is considered likely to occur and poses a major risk. Reassess Risk and Likelihood considering any Mitigation Measures to determine the Residual Significance using Matrix in Table 9.3 Note: In the vicinity should be inferred as within the likely sphere of influence. TABLE 9.2 SENSITIVITY VERSES SEVERITY = RISK Sensitivity Severity Marginally Sensitive Sensitive Very Sensitive Negligible No Risk No Risk No Risk Low Minor Minor Moderate Medium Minor Moderate Moderate High Moderate Moderate Major TABLE 9.3 RISK VERSES LIKELIHOOD = SIGNIFICANCE Likelihood Risk Unlikely Possible Likely No Risk Negligible Negligible Negligible Minor Negligible Minor Minor Moderate Negligible Minor Moderate Major Minor Moderate Major 9.4 Baseline Assessment Site History A review of historical Ordnance Survey plans highlighted that the Facility site was open space (presumably agricultural land) until 1969 when both the site and surrounding land was developed as an opencast quarry. It is understood that this was part of the Blue Circle cement works (now Lafarge) with the limestone used in the manufacturing process. The OS plan dated shows that the site is no longer within the working area of the quarry, appearing as open space. The former use of the site as an opencast quarry, which has now been backfilled with quarry waste material (as proven by the intrusive works), could have resulted in the 188

10 presence of gas within the landfilled material. Soils have been placed over the backfilled material consisting of clayey, silty, sandy and gravely soils from the glacial drift deposits that are considered to have been above the working face. The early evidence of historical wells (1884 OS plan) in the area suggests that there is some source of groundwater with abstraction on a small scale, in this locality. The depth of the wells or the strata from which groundwater was abstracted is not known. Site Description The topography of the Facility site is gently sloping, with a decrease in elevation from 40m AOD from the access road in the southwest to 25m AOD towards the north-east corner of the site, gently sloping from southeast to the north-west. Surface cover is mainly grass and small shrubs. Site Surroundings The Facility site is located within the land ownership of Oxwellmains Landfill and the working area of the landfill is located to the east of the Facility site. Lafarge Cement Works is located north and north-west of the site. To the north of the site is the main Edinburgh to London east coast rail line and the A1 trunk road is located to the south of the site. In the surrounding area, outwith the land ownership of Oxwellmains Landfill, lies predominantly agricultural land. Approximately 1.8km to the north-east is Barns Ness coastline, a designated SSSI. The nearest residential areas and properties are located in Meikle Pinkerton, Easter Meikle Pinkerton and Thurston located approximately 500m southwest and 1km southeast of the Facility site. The Dry Burn is located approximately 1.5km to the east of the site boundary. Drift Geology Information on the underlying geology of the site at Oxwellmains, Dunbar has been obtained from British Geological Survey (BGS) maps, sheet 33E (Dunbar), 1978, at a scale of 1:50,000. This review identified that the site is underlain by man-made deposits of waste and or natural earth materials filling a former opencast excavation. Surrounding the site is an area of glacial meltwater deposits comprising of moundy deposits and terraced spreads of bedded sand and fine to course grained gravel, with associated deposits of laminated silt and clay. It is likely that these deposits would have underlain the site prior to the opencast excavations and may have been used as fill material. Intrusive site investigation works undertaken as part of Oxwellmains Landfill PPC Application (2004) and historic borehole data has indicated reworked superficial deposits to 17m bgl, providing an indication of ground conditions at the Facility site. However, this investigation was not completed to bedrock. The above site investigation also encountered pockets of white/grey flue dust deposits which are presumed to be the waste product from the cement industry which were deposited when in-filling the quarry. Intrusive site works carried out in March 2007 (RPS Interpretative Site Investigation Report, August 2007) for the Facility site confirmed that reworked glacial deposits and quarry waste material are present across the entire site. The re-worked deposits ranged in thickness from 11.9m bgl to 20.7m bgl. It should be noted that no pockets of flue dust were encountered during the site works however the presence of these cannot be discounted. 189

11 Solid Geology Published records detail that bedrock comprise strata of the Lower Limestone Group (LLG) of sandstone, siltstone, mudstone, limestone and fossiliferous calcareous siltstones and mudstones contained within the Carboniferous Limestone Series. The thickness of the LLG is between 90-95m. The strata dips between 5 and 15 to the north and north-east and appears to fold into a syncline. To the southwest is a major fault known as the Innerwick Fault and is downthrown to the north-east, trending in a north-west southeast direction and exposes the older Devonian and Silurian bedrock. The LLG is faulted across the outcrop, however these are not directly associated with the site. Faulting is evident around the site directly to the north, south-west and southeast, trending north-east to southwest. Records indicate the presence of sensitive geological features within the surrounding area of the Facility site. Barns Ness coastline approximately 1.8km to the north-east is a designated geological and botanical SSSI and is a noted Geological Trail. Intrusive site investigation works undertaken as part of Oxwellmains Landfill PPC Application (2004) and historic borehole data indicate that bedrock has been encountered at the adjacent landfill between approximately 11m AOD and 19m AOD and as such it was anticipated that bedrock would be encountered at similar depths at the Facility site. The intrusive site investigations (March 2007) carried out for the Facility site identified rockhead at a depth of 24.67m AOD (12m bgl) in the southwest of the site and 2.84m AOD (20.8m bgl) towards the north of the site. Bedrock was exhibited as red grey sandstone and grey fractured limestone. The sandstone was proven to extend to depths of 50m bgl. Mining History There are five fossiliferous limestones within the LLG, the thickest of these being the Middle Skateraw and Upper Longcraig Limestones, and these have been extensively worked. Thin coal seams (1m 5.5m) occur beneath some of the limestones and mine workings are known to exist in the area that exploited these seams. Depths of workings are known to be between 32.55m AOD and 35.9m AOD, as reported in the Oxwellmains Landfill PPC Application (2004). This suggests above the current level of the site (40m AOD to 25m AOD). It has been presumed that if mine workings were present beneath the site they would have been destroyed during opencast quarrying. The site is located within a BGS Recorded Mineral Site, this is registered as an opencast works operated by Blue Circle Industries Plc, now ceased, and quarried the Lower Limestone Formation. Contaminated Land The results of the site investigation reveal that there is limited impact to site soils. The soil results are provided in Appendix 9 within the Interpretative Site Investigation Report. None of the results exceeded the soil guideline values (SGV) or generic assessment criteria (GAC) for a Commercial and Industrial land use scenario. Gas monitoring carried out at the site on four occasions has revealed no presence of methane gas and only slightly elevated concentrations of carbon dioxide, maximum concentration of 4.3% recorded in borehole T3 (see Appendix 8 of 190

12 Interpretative Report for location of boreholes) on the second round of monitoring. Results are provided within Appendix 8 of the Interpretative Report. Where any impacts are evident these are typically associated with the made ground and are present at relatively minor levels. These are not considered likely to present any significant implications on the future land use at the Facility site. 9.5 Impact Assessment Potential Receptors Prior to considering potential impacts associated with the proposed works, it is necessary to identify any existing sensitive receptors, namely: nearby residential properties Easter Meikle Pinkerton located approximately 500m to the south-west of the proposed EfW site; nearby commercial/industrial properties the existing Oxwellmains Landfill located approximately 300m to the east and Lafarge Cement Works 400m north-west of the Facility site; underlying groundwater; underlying shallow soils; and Barns Ness SSSI. Further discussion of the potential impacts upon these receptors is provided below in conjunction with any recommended mitigation measures. There are not considered to be any sensitive receptors, at risk (with regard to contaminated soils) from site construction works, facility operations or decommissioning works, of the following types: human health receptors adjacent to site (i.e. direct bounding the site); ecological receptors on site or in the vicinity of site (i.e. within the likely sphere of influence); or property, either in the form of crops, livestock or buildings in the vicinity of site. Potential Impacts (Sources and Pathways) Given the present knowledge of the Facility, the following sources that have the potential to generate impacts require consideration: earthworks of made ground and soils potentially impacted by historic site land use; the use of spoil generated on site to form landscaping bunds; displacement of shallow soil gases; storage of fuels and materials during construction; storage of fuels, materials by-products during operations; and surface runoff. Further discussion of these potential impacts is provided below in section 9.6 in conjunction with any recommended mitigation measures. 191

13 9.6 Mitigation Construction The degree of earthworks required as part of the development is unconfirmed at present, however, it is likely that excavation of areas of made ground will be undertaken for foundations in low bearing pressure areas. Any excess excavated spoil may also be used in the formation of landscaping bunds. Excluding the results of the intrusive investigation, considering the potential for the presence of impacted soils associated with the historic use of the site, and the presence of made ground, there may be risks posed to human health receptors (i.e. off-site residents and future site users). These would be due to handling of the material and any subsequent mobilisation in the form of dust generation. However, the nearest receptor, the residential property to the southwest of the site, is located approximately 500m away and the nearest industrial receptor is located approximately 300m east and 400m north-west (from the main body of the Facility site). Given these distances and now considering the absence of significant contaminants identified by the site investigation, these impacts are anticipated to most likely, be minimal. However, it is anticipated that a construction management plan should be in place to ensure the potential for dust generation is minimised, by adopting standard good working practices, as a matter of course. Construction works will require the storage of fuels and materials. The daily storage and use of these, and the potential for spill incidents may result in potential impact upon the localised shallow soils. In order to mitigate these potential impacts a construction environmental management plan should be in place to ensure the potential for spillages is minimised by adopting standard good working practices and demonstrating compliance with regulations, such as SEPA Pollution Prevention Guidelines. It is considered due to the distance of Barns Ness SSSI (1.8km) from the Facility that it is sufficiently far enough away to remove potential pollutant linkage and so considered to be no risk. Operation Any excess excavated spoil may be reused on site in the formation of landscaping bunds. Given that the source of this material has been subjected to historic brownfield land use, or the material may comprise made ground, there is the potential that excavated spoil may be impacted by historic contamination of the Facility site. This has the potential to pose a theoretical risk to off site receptors (e.g. residential properties located 500m to the west of the Facility site), through wind blow and subsequent inhalation or contact, should the backfilled soil remain exposed. However, as above, given these distances and the lack of significant contaminants identified by the site investigation, these impacts are considered to be most likely minimal. To ensure this is the case any made ground reused on the site should be visually monitored and if any unexpected material or deviation from the current understanding of the site conditions, is encountered then the soils should be reassessed and potentially analysed, to determine their condition and hence suitability for use in landscaping areas. The incorporation of inert topsoil above any areas of reused soils or the presence of vegetation will assist in reducing the potential for windblown impacted dust generation by providing a capping or preventative layer above any exposed impacted soils. However, based on results, generally the 192

14 condition of the site soils are such that it is considered unlikely that significant risks may be generated by the re-use of site soils, from a contamination perspective. The Facility will require the storage of a number of raw materials and by-products from the operation of the Facility. These include predominantly solids although some fuels and liquids will also be stored on site. The storage and use of fuels on site, and the potential for spill incidents, has the potential to impact upon localised shallow soils. However, it is assumed storage areas will be located on hardstanding areas and include appropriate control measures to mitigate against spillages. The primary aqueous discharges at the Facility site will comprise surface runoff and solid discharges will comprise bottom ash and flue gas treatment residue (fly ash). Surface runoff has the potential to contain low levels of contaminants (under normal circumstances) associated with the daily operation of the Facility. Collection of surface runoff in the proposed site drainage system will mitigate the potential to impact upon shallow site soils. It is considered that the main solid discharges (i.e. bottom ash and fly ash) will not generate any potential risks to geological receptors as these wastes will be collected, contained and removed from the site under controlled conditions, e.g. sealed conveyors and silos fitted with dust filters. Other materials stored on site include Municipal Solid Waste (MSW), Auxiliary Fuel (Light oil), Ammonia, Phosphate, Activated Carbon, Sodium Bicarbonate, Maintenance Oils and greases and Boiler Water Treatment Chemicals (Hydrochloric Acid, Sodium Hydroxide, Sodium Phosphate). All storage containers will be adequately bunded, located on areas of hardstanding and fitted with level or leakage alarm systems. All deliveries will be monitored by site personnel to ensure deliveries occur without incident. Storage facilities for liquid fuel will be bunded to the required specifications and supplied with instructions for dealing with spillages. An up-to date list of all raw materials will be used on-site and maintained by the relevant personnel. A Material Safety Data Sheet (MSDS) will be kept for each chemical and material and held in the appropriate location. 9.7 Cumulative There are not considered to be any significant cumulative impacts associated with the proposed development on the geological regime at the Facility site. 9.8 Statement of Significance Assessment of Significance The assessment of the significance of the impacts is presented in the table below. These have been assessed in the first instance assuming no mitigation measures are in place, hence: spoil material (i.e. made ground) material is present in exposed landscaping bunds; no dust mitigation measures are employed during construction earthworks; construction fuels and materials are stored on site in an uncontrolled manner; the storage of raw material and by-products are not housed in suitably designed structures; and surface runoff is not controlled. 193

15 TABLE 9.4 ASSESSMENT OF SIGNIFICANCE Activity Impact Risk Significance Sensitivity Severity Risk Risk Likelihood Significance Construction Earthworks Fuel/Liquid Storage Operation Landscaping Bunds Fuel/Liquid Storage Surface Runoff Windblown dust to adjacent receptors Spillages on shallow soils Reuse made ground and generation of windblown dust Spillages on shallow soils Discharge to shallow soils Sensitive Low Minor Minor Unlikely Negligible Marginally Sensitive Low Minor Minor Likely Minor Sensitive Low Minor Minor Unlikely Negligible Marginally Sensitive Marginally Sensitive Low Minor Minor Likely Minor Low Minor Minor Likely Minor Assessment of Residual Significance The assessment of the residual significance of the impacts is presented in the table below. These have been assessed assuming mitigation measures are in place, hence: spoil material (i.e. made ground) is tested/capped in landscaping bunds, if required; dust mitigation measures are employed during construction earthworks; construction fuels and materials are stored on site in accordance with a appropriate management systems; the storage of raw material and by-products are housed in suitably designed structures; and surface runoff is controlled. TABLE 9.5 ASSESSMENT OF RESIDUAL SIGNIFICANCE Activity Impact Mitigation Measure Residual Significance Risk Likelihood Significance Construction Earthworks Windblown dust adjacent receptors to Construction method statement and best practice operating procedures. Minor Unlikely Negligible 194

16 TABLE 9.5 ASSESSMENT OF RESIDUAL SIGNIFICANCE Activity Impact Mitigation Measure Residual Significance Risk Likelihood Significance Fuel/Liquid Storage Spillages on shallow soils Construction method statement and best practice operating procedures. Minor Unlikely Negligible Operation Landscaping Bunds Fuel/Liquid Storage Surface Runoff Reuse made ground and generation of windblown dust Spillages on shallow soils Discharge to shallow soils Suitability for use proven by validation testing (only if required) of soils or Minor Unlikely Negligible topsoil and vegetation capping installed. Engineered design. Minor Unlikely Negligible Engineered design. Minor Unlikely Negligible Proposed Monitoring No monitoring is proposed. Statement of Significance The assessment has identified a number of potential impacts that may be associated with the construction and operation of the Facility. These have accounted for the construction elements and the nature of the proposed development. In consideration of these elements, in relation to the baseline conditions at the Facility site, these impacts can be mitigated to levels considered to be of negligible significance through the implementation of construction management practices or readily practiced engineering design principles although, even in the unmitigated state potential impacts are deemed to be minor at worst, it is anticipated that mitigation measures should still be employed as part of best practice construction, design and operating requirements. This assessment has been founded on the principles of contaminated land assessment and the endorsement of mitigation measures will ensure compliance with current construction, design and management practices beyond the context of a contaminated land assessment. 195

17 WEST SITE BOUNDARY EAST LAFARGE CEMENT WORKS PROPOSED INDUSTRIAL DEVELOPMENT (Energy from Waste Facility) R3 DUNBAR LANDFILL Soil / dust ingestion P1 Dermal contact P2 P8 Storage of fuels & materials P3 Future site users R1 Groundwater extraction at Lafarge R4 Groundwater R2 P6 Gas/vapour migration Direct contact with building and permeation of water supply pipes/services R3 MADE GROUND (QUARRY FILL MATERIAL) Potential contamination from historic made ground / quarry fill Lateral groundwater migration (through saturated zone) P7 P5 LOWER LIMESTONE GROUP (Sandstone, Siltstone, Mudstone, Limestone) Gas/vapour migration P6 Pockets of Flue dust Potential Groundwater contamination from made ground P4 Drawing ref: S:\0893saw Dunbar\Drawings\0893_001 - Initial Conceptual Site Model (Fig9.1).cdr P1 P2 P3 P4 P5 P6 P7 P8 R1 R2 R3 R4 Text Text Soil / dust ingestion Dermal contact Direct contact with building materials Migration through unsaturated zone Migration through saturated zone Vapour migration through unsaturated zone Permeation of water supply pipes Surface Run-off Site users / future site users Underlying groundwater Property Underlying Shallow Soils Source Pathways Text Receptor Major Aquifer 45 Timberbush Bernard Street Leith Edinburgh EH6 6QH T F E rpsed2@rpsgroup.com W Date: 30/08/07 Scale: NTS Rev: Job No: SAW0893 Drawn: NF Checked: AM Client: Viridor Waste Management Ltd Project: Energy from Waste Facility, Oxwellmains Landfill Title: Initial Conceptual Site Model Figure No: 9.1