The client, a major mineral extraction company, intended to apply for planning permission to extend an existing quarry located in sand deposits which form a locally important minor aquifer. Environmental Simulations International was instructed to provide specialist hydrogeological services to assess the potential hydrogeological impacts associated with the scheme and design mitigation measures where required.

The proposed extension was adjacent to current quarrying operations where dewatering was being undertaken to allow dry working of the mineral. There was to be a further period of dewatering during the restoration works. The site was close to a hydrologically sensitive SSSI and the work needed to address issues related to this site.

The scope of work for the project was undertaken in four stages;

	Collection of available information regarding geology, groundwater and surface waters and the design of a field programme to obtain information necessary for impact prediction.
	Development of a sound conceptual model of the groundwater flow system and development of simple 2D models using ESI’s Winflow package for impact prediction.
	Prediction of the area impacted by drawdowns as well as the estimation of potential dewatering requirements.
	Presentation of the findings in the form of a concise technical report for submission to relevant authorities in support of the planning application.

The likely dewatering yield and drawdown in the aquifer were evaluated and the impact of the proposed dewatering assessed. The drawdown at the site was evaluated and it was predicted that following restoration, water levels in the lake would be largely controlled by the elevation of recovered groundwater levels.

ESI also proposed that monitoring of groundwater be undertaken to provide further confidence that no adverse impacts would occur and facilitate optimum water management during the works.

The report submitted by ESI was incorporated into the planning application, which was subsequently approved.

Please contact ESI (01743 276100 / email) for more information on 'Hydrogeological Assessment of a Sand and Gravel Quarry'.

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