Geoenvironmental Appraisal & Coal Mining Risk Assessment North Tyneside Council

The Cedars, North Shields. Geoenvironmental Appraisal North Tyneside Council

Geoenvironmental Appraisal & Coal Mining Risk Assessment – The Cedars, North Shields

DBS supported North Tyneside Council with the development of a site in North Shields known as “The Cedars”.

Client: North Tyneside Council

Summary

The site comprised a parcel of brownfield land that was formerly used as a nursing home; it was cleared of above ground structures including a boiler house and was proposed for redevelopment for residential housing.

DBS supported the council through site characterisation which commenced with a Phase 1 Geoenvironmental Desk Study report and a Coal Mining Risk Assessment (CMRA) report.

The Phase 1 report established the sites Conceptual Model, and potential pollutant linkages were identified for human health resulting from the sites past use and location, and also ground gas risks.

The coal mining risk assessment report identified potential shallow mining risks due to the presence of the Metal (aka Top Main) coal seam which outcropped through the site, and also risks to ground stability due to the presence of a historical mine shaft located next to the site entrance and risks of the shaft providing a conduit for mine gas in deeper workings to affect surface also identified.

A geoenvironmental ground investigation was subsequently designed by DBS to obtain pollutant linkages and ground conditions.

The investigation comprised shallow boreholes sunk to 5.0m bgl with a window sampler drilling rig, along with cable percussion boreholes to 10m bgl.

Rotary boreholes were also sunk to 30m bgl to probe the position of the Top Main coal seam and trial trenches were excavated at the recorded position of the historical mine shaft, including its recorded 10m departure zone. As part of the mine shaft prospecting work 50 No. window sample boreholes were also sunk on a grid basis to identify the location of the shaft.

A ground gas and groundwater level monitoring programme was also completed at the site post completion of the ground investigation works following the requirements of BS8485 guidance.

DBS supervised all specialist contractors appointed on the scheme and prepared detailed interpretative reports on the completion of the works, including information to support foundation design.

A Phase 2 Geoenvironmental interpretative report was prepared that updated the sites CM and provided a final risk assessment that identified that risks to receptors comprising human health, controlled waters and property were not present, and that the site could be taken forward without any need for a remediation options appraisal and/or site Remediation Strategy.

The shallow mining appraisal confirmed that shallow workings were not present on site, and the mine shaft prospecting works did not identify a shaft at its recorded location; the location was recorded by The Coal Authority from old NCB shaft records but no original source material was available for the shaft.

The work allowed the site redevelopment proposals to proceed safely and all work was approved by the Environmental Health Team of North Tyneside Council to allow planning condition discharge.

DBS also supported the client with detailed dialogue on the coal mining position with The Coal Authority helping to secure coal mining legacy planning condition discharge.

DBS supported North Tyneside Council to successfully deliver the site for residential use.

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