Buchanan and St Ambrose Independent Review: final report

Chapter Seven: Soil Quality

7.1 Chapter 4 sets out the history of examining the site for contaminants at the time when the site was being identified as an option and through the planning process and beyond. This started with a Human Health Risk Assessment in 2008 which identified a number of concerns, a Generic Quantitative Risk Assessment in 2009 to assess these risks in more detail and a Site Specific Risk Assessment which determined the risks from the point of view of its use as a secondary school. These reports as we reviewed in Chapter 4 of this report were considered by officials as part of the planning application.

7.2 Given ten years have passed since these assessments were completed and public concerns have risen hugely in recent months, we took the view that a more up-to-date assessment of soil quality was needed on the site.

7.3 We stress that this was a precautionary approach with the aim being to consider risks from contaminants that may be present in soil to human health based on the current use of the site as a secondary school.

7.4 For background, in the UK land contamination is assessed using a risk-based approach taking account of the magnitude (severity of the hazard) and likelihood (probability) of occurrence. A 'receptor' is something that could be adversely affected by contamination (e.g. people, an ecological system, property or a water body). A 'pathway' is a route or means by which a receptor is or could be exposed to or affected by a contaminant. A 'contaminant source' is a hazard but it can only pose a risk to a receptor where a pathway is present. A risk can therefore only be released where a contaminant source, pathway and receptor are all in place, referred to as a 'pollutant linkage'.

7.5 We initially obtained independent expert advice from Fife Council Environmental Protection Team who reviewed the previous site investigation and site-specific risk assessment documents, recommendations for remediation works and validation of the works.

7.6 On the basis of this advice, we instructed an independent environmental consultancy, RSK Environment Ltd., on 16 July to carry out rigorous, independent soil testing on the school campus.^[45] The aim was to assess the current presence of any contamination by determining the concentration of a wide range of chemicals in the soil within areas of grass cover across the site. Samples were not needed from underneath the school buildings, car park areas or underneath the synthetic playing fields because the surfaces themselves form barriers to any potential exposure to the soils beneath. The buildings, car parks and playing fields exclude pathways to the surface.

7.7 A total of fifty trial-pits were excavated across the site, to depths varying between 0.3m and 0.6m. Up to 74 soil samples were examined and scheduled for tests on a wide range of contaminants of potential concern. For completeness, sampling and testing of soils from raised beds and a polytunnel used for growing fruits and vegetables was also carried out at the same time. Attached to this Report is a map showing the locations of sampling by RSK.

7.8 In addition, as public concern about unconfirmed radioactive sources within the historic landfill had been reported to the review team, radiological monitoring was undertaken to test the soil arisings from the trial-pits and within the Buchanan High School Science/Technical corridor. All radiological monitoring results were within background ranges for radioactivity providing evidence that radioactive sources are not present in shallow soils or in this area of the building.

7.9 The trial-pits revealed that the grassed areas on site are underlain by topsoil and 'made ground', consistent with the development history of the site. The made ground was a sandy soil but contained various materials such as ash, brick and concrete pieces, glass fragments and concrete. Other items such plastic wrappers, bottles, clothing and shoes were encountered occasionally. The soils from the trial-pits were examined carefully and there was little visual evidence of contamination such as staining of soils or presence of volatiles (odours/ headspace testing).

7.10 The soil samples obtained from the trial-pits and raised beds were analysed for a very comprehensive range of chemicals at a specialist environmental laboratory. The testing was selected taking into account the possible contaminants associated with the site history and those found in previous investigations. It was also extended to identify whether other substances could be present taking account of possible uncertainties and the nature of this review. The chemical analysis covered over 150 different compounds, including heavy metals, hydrocarbons, asbestos, volatile organic compounds (VOCs), pesticides and dioxins.

7.11 Potential chronic (long-term exposure) risks have been assessed to current site users from exposure to contaminants, where present, in the soils tested. The laboratory testing data has been assessed by RSK in accordance with technical guidance published by authoritative bodies, such as Defra and the Environment Agency, and accepted by regulatory authorities in Scotland. 'Generic Assessment Criteria' (GAC) are values for concentrations of contaminants in soils that have been developed to be protective of human health based on a series of assumptions about the characteristics and behaviour of sources, pathways and receptors for a particular land use.

7.12 In this case, the GAC were selected based on a 'typical' secondary school land use, where the most sensitive receptor is identified in guidance as a girl 11-16 years old. The pathways considered are direct skin contact with soils, ingestion of soil and dust generated from soils, and breathing in any dust or vapours generated from the soils being tested. These GAC also allow assessment of potential risks, and are protective of adults who work on the site for many years and on a daily basis. It does not cover risks for maintenance workers who may need to dig up soils whose potential for exposure to soils is greater but mitigated by good working practices. In addition, ingestion via consumption of fruit and vegetables has been considered for the samples taken from the raised beds only, leading to use of a different set of GAC.

7.13 The laboratory test data is compared against the GAC values to assess the level of risk. Where the soil concentrations are below the GAC, the risk is considered not to be realised and no further assessment is required. Where the soil concentrations are above the GAC, this does not necessary mean that a risk is realised; either more detailed (site-specific) risk assessment or remediation works may be carried out on precautionary basis.

7.14 RSK's full results will be published shortly, once the risk assessment and reporting process has been completed. The key findings to date are summarised below:

7.15 In conclusion, the concentrations measured in soils, with the exception of PCBs at one location, are not of concern and represent a low risk to site users, including pupils, teachers and visitors.

7.16 The test results for the soil samples from the raised beds shows that the concentrations of contaminants are not above GAC and accordingly we consider that no further assessment is required.

Conclusion by Review Team

7.17 The testing and analysis described above has been informed by expert advice, been undertaken in a thorough and systematic way, and has covered a wide range of potential contaminants. The laboratories used are all accredited and the risk assessment (GAC) is set at a precautionary level.

7.18 The work has identified one sample pit located in the south east part of the site (HP50) which been found to contain higher than expected concentrations of PCBs (polychlorinated biphenyls). On a strictly precautionary basis, remediation is advised following further delineation.

7.19 The location of HP50 is on the periphery of the site and can be isolated from site users whilst remediation is undertaken.

Recommendation

7.20 We would be supportive of a decision of North Lanarkshire Council as Education Authority to open the schools, on the basis that North Lanarkshire Council are undertaking (and commencing with a view to completion as soon as possible) full and independently verified remediation of area designated HP50, entailing the removal of the contaminants present there or otherwise render the area safe from the risks from those contaminants.