Grassmoor tar lagoons remediation scheme

The site of the Grassmoor Country Park, Chesterfield, UK, was formerly six lagoons formed within spoil tips associated with the extensive workings of the former Grassmoor colliery. Historically, the lagoons were used for treating effluent from the former Grassmoor gasworks and coking plant. After Grassmoor coking plant’s demolition, the lagoons continued to treat effluent from the nearby Avenue coking plant.

In September 2009, Derbyshire County Council appointed RemedX as the principal contractor to remediate the tar lagoons. Initially, we completed ground investigations and pilot trials followed by an environmental impact assessment, which supported planning submission for remediating the site.

A key aspect of the planning work involved refining the conceptual site model and risk modelling to determine site-specific target levels that would be protective of an open-space end-use and the nearby brook running through the country park. Particular attention was given to the assessment of the remediation treatment options and air quality.

Through working with other RSK companies, RemedX was able to gain planning and regulatory approvals for the design as part of a collaborative project team. RemedX submitted the planning application in July 2010; by December 2011, the planning committee granted permission. During the planning process, RSK’s ecological team identified a badger sett and relocated it to a new, purpose-built sett outside the working area.

RemedX scientists selected ex-situ bioremediation as the most sustainable treatment technique. The remediation process was kept within the original time frame by optimising the process using a pretreatment phase. Concurrent to the remediation process, we monitored the air quality on- and off-site and routinely sampled it for targeted compounds, dust and toxic metals at several locations.

Treatment work began in July 2012 and remedial work was completed in December 2014. Land forming work commenced in January 2015. Seeding of the newly formed park took place the following autumn and resulted in a wildflower-rich grassland and an increase in biodiversity.