Insight type
Case study
Blurb
Englobe was a subcontractor to Laing O’Rourke (LOR) whose scope included construction and commissioning of a large-scale sewage treatment plant.
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Laing O'Rourke, Davyhulme
Contaminated Soil Management
Englobe was a subcontractor to Laing O’Rourke (LOR) whose scope included construction and commissioning of a large-scale sewage treatment plant.

Approach

The scope of Englobe’s works included significant earthworks (200,000m³) with soils containing asbestos and geotechnically unsuitable materials that were managed appropriately, ground improvement by soil modification to form geotechnically suitable development platforms, remediation of hydrocarbon contaminated soils, removal of piling obstructions, water treatment, environmental monitoring and installation of piling mats.   Asbestos monitoring was also undertaken throughout the programme to verify that control measures were mitigating risks associated with disturbance of asbestos containing soils. 

 

Englobe undertook Early Contractor Involvement to help optimise the design and maximise the recycling and re-use of soils on site. It also provided all testing and reporting required to discharge the contaminated land planning conditions and satisfy stringent environmental monitoring requirements to ensure the works were delivered without significant disturbance to neighbouring residential properties.

Title
Large-scale sewage treatment plant
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Laing O’Rourke, Davyhulme
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Laing O’Rourke, Davyhulme
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Laing O'Rourke, Davyhulme

Challenge

Englobe was engaged at an early design stage by LOR’s team to help optimise and sequence the earthworks, with Englobe bringing expertise on the recycling and re-use of soils to reduce cost and maximise sustainability. This enabled LOR to benefit from lower overall costs through processing, remediating, modifying contaminated soil and geotechnically poor soils for re-use within the construction platform. Englobe’s environmental management expertise on a site where relations with adjacent residents and other key stakeholders, such as the local council’s Environmental Health Department, were critical to the client.

 

 

Risk was managed by:

  • Early engagement with the LOR’steam to integrate overall enabling works package to minimise overall build programme.
  • Provision of fixed price contract based on through understanding of waste volumes, treatment options and programme risk.
  • Robust environmental management to mitigate exceedances of defined monitoring parameters.
  • Design of on-site treatment for difficult soil and water wastes that provided alternatives at lower cost to off-site disposal and greater flexibility should volumes increase.
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As a result of Englobe’s design and contracting works:
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Statistic
Over 99%
Caption
of excavated soils were available for re-use on site.
Statistic
9,700m3
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of contaminated soil treated to be suitable for re-use on site and diverted from landfill.
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5% CBR
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was reached in terms of development footprints to provide working platforms and minimise requirement to import crushed stone.
  • The risk of excavating and re-using large quantities of soil containing asbestos fibres were mitigated and ambient fibre limits respected.
  • All works completed without disturbance to the site’s neighbours.

 

 

Contract Start Date: May 2015

 

Completion date: February 2017

 

Contract Value £6,100,000