Last edited 22 Nov 2016

Ground conditions

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Contents

[edit] Introduction

A thorough investigation and assessment of ground conditions and stability is an essential stage of any project in order to determine issues such as:

  • Whether a site is suitable.
  • Where the best place to locate any buildings or infrastructure might be.
  • Types and sizes of any foundations.

An assessment of ground conditions in relation to construction projects typically includes geology, hydrology, hydrogeology and soil conditions of a site and surrounding, along with contaminated land. A site investigation report will highlight any findings that may affect the construction of the works and identify any health and safety concerns.

The following conditions might be considered:

  • General landforms.
  • Flood risk.
  • Historical or present risk of landslides or subsidence.
  • Soil types.
  • Drainage and run-off.
  • The water table and any natural springs or waterlogged soils.
  • The proximity of the site to any proposed buildings or excavations.
  • The presence of any expansive clays.
  • The historic use of the site such as buried structures, contamination, earthworks and uncompacted fill.

Typically, for a large construction project where an Environmental Impact Assessment (EIA) is required, an assessment of the impacts on ground conditions is necessary. This would usually include a desk based assessment and a field survey.

The exact content of the desk based assessment would vary depending on the project in question, however it could include an assessment of the following sources of information relevant to the site and surrounding area:

The desk based assessment would inform the requirements for any field surveys. The field surveys are likely to include geo-environmental testing of the soil and groundwater for contamination through the excavation of trial pits or holes. Deeper investigations may be required using boreholes or dynamic probing.

[edit] Legislation and planning policy

[edit] Legislation

The predominant pieces of legislation that are relevant to ground conditions include:

  • Agriculture Act 1986.
  • Construction (Design and Management) Regulations 2015.
  • Contaminated Land (England) (Amendment) Regulations 2012.
  • Control of Pollution (Oil Storage) (England) Regulations 2001.
  • Control of Substances Hazardous to Human Health 2002 (as amended).
  • Environmental Damage and Liability (Prevention and Remediation) Regulations 2009.
  • Environmental Permitting Regulations (England and Wales) 2010.
  • Environmental Protection (Duty of Care) Regulations 1991 (as amended 2003).
  • Environmental Protection Act 1990 (as amended by the Environment Act 1995).
  • Hazardous Waste (England and Wales) Regulations 2005.
  • Landfill (England and Wales) Regulations 2002.
  • Landfill Directive 1999/31/EC 1999.
  • Landfill Tax (Contaminated Land) Order 1996.
  • Town and Country Planning Act 1990.
  • Water Act 2003.
  • Water Resources Act 1991 (WRA 1991) and Amendment 2009.
  • Wildlife and Countryside Act 1981 and (Amendment) Act 1985 (as amended by the Countryside and Rights of Way Act 2000).

[edit] Planning policy

The planning policies within the National Planning Policy Framework that are of direct relevance to geology, soils and contaminated land are:

109 The planning system should contribute to and enhance the natural and local environment by:

  • Protecting and enhancing valued landscapes, geological conservation interests and soils.
  • Recognising the wider benefits of ecosystem services,
  • Preventing both new and existing development from contributing to or being put at unacceptable risk from, or being adversely affected by unacceptable levels of soil, air, water or noise pollution or land instability.
  • Remediating and mitigating despoiled, degraded, derelict, contaminated and unstable land, where appropriate.

110 In preparing plans to meet development needs, the aim should be to minimise pollution and other adverse effects on the local and natural environment. Plans should allocate land with the least environmental or amenity value, where consistent with other policies in this Framework.

111 Planning policies and decisions should encourage the effective use of land by re-using land that has been previously developed (brownfield land), provided that it is not of high environmental value. Local planning authorities may continue to consider the case for setting a locally appropriate target for the use of brownfield land.

112 Local planning authorities should take into account the economic and other benefits of the best and most versatile agricultural land. Where significant development of agricultural land is demonstrated to be necessary, local planning authorities should seek to use areas of poorer quality land in preference to that of a higher quality.

113 Local planning authorities should set criteria based policies against which proposals for any development on or affecting protected wildlife or geodiversity sites or landscape areas will be judged. Distinctions should be made between the hierarchy of international, national and locally designated sites so that protection is commensurate with their status and gives appropriate weight to their importance and the contribution that they make to wider ecological networks.

117 To minimise impacts on biodiversity and geodiversity, planning policies should aim to prevent harm to geological conservation interests.

120 To prevent unacceptable risks from pollution and land instability, planning policies and decisions should ensure that new development is appropriate for its location. The effects (including cumulative effects) of pollution on health, the natural environment or general amenity, and the potential sensitivity of the area or proposed development to adverse effects from pollution, should be taken into account. Where a site is affected by contamination or land stability issues, responsibility for securing a safe development rests with the developer and/or landowner.

121 Planning policies and decisions should also ensure that:

  • The site is suitable for its new use taking account of ground conditions and land instability, including from natural hazards or former activities such as mining, pollution arising from previous uses and any proposals for mitigation including land remediation or impacts on the natural environment arising from that remediation.
  • After remediation, as a minimum, land should not be capable of being determined as contaminated land under Part IIA of the Environmental Protection Act 1990.
  • Adequate site investigation information, prepared by a competent person, is presented.

122 In doing so, local planning authorities should focus on whether the development itself is an acceptable use of the land, and the impact of the use, rather than the control of processes or emissions themselves where these are subject to approval under pollution control regimes. Local planning authorities should assume that these regimes will operate effectively. Equally, where a planning decision has been made on a particular development, the planning issues should not be revisited through the permitting regimes operated by pollution control authorities.

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