Increased Quarry Depth – Hydrology: Cemex

Case Study

CemexIn 2009 CEMEX instructed us to prepare a hydrogeological impact assessment to support plans for an increased depth of working at Freemans Quarry. Planning permission for the quarry is subject to a number of conditions relating to groundwater including impact assessments before the quarry can be deepened below the water table. We produced a detailed report supporting the planned increase in depth and subsequent restoration of the quarry.

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CEMEX UK Materials Ltd operates Freemans Quarry at Broadfield Down, Somerset, for the extraction of Carboniferous Limestone. The quarry is subject to a Section 106 agreement which requires that quarrying activities should not intercept the water table without CEMEX agreeing mitigation measures with the Mineral Planning Authority. This is in order to allow further hydrological and hydrogeological data to be collected before working below the water table.

 

We have assisted CEMEX over a number of years in preparing annual reviews of the hydrological monitoring data for the site. In 2009 CEMEX instructed ESI to prepare a hydrogeological impact assessment to support the planned increased depth of working, and subsequent restoration of Freemans Quarry.

 

The report concluded that only occasional, limited dewatering would be required to work the next bench and that any minor impacts from working the final bench could be mitigated by discharge of the water to local soakaways. No significant impacts from the proposed restoration were identified.

 

In reviewing the report, the Environment Agency offered to provide outputs from its regional water resources study to allow a more quantitative approach to be adopted. We therefore used the outputs from the Agency’s 4R recharge-runoff model to develop transient water balances for the local area in order to quantify the quarry dewatering more accurately.

 

This work supported the findings of the original investigation.