Prepared by the Coal Authority and presented to South Tyneside Council & Durham County Council 25 September 2012 Tyne & Wear Aquifer Protection Scheme

Context - Aquifers Aquifer – an underground layer of water-bearing, permeable rock or drift deposits from which groundwater can be extracted An aquifer is filled by rain or melted snow that drains into the ground from the surface and acts as a reservoir for groundwater. Wells drilled into the aquifer allow this groundwater to be pumped out for drinking, agriculture and industrial uses. The Environment Agency aims to protect groundwater and coastal waters from pollution by controlling discharge of certain substances, such as mine water.

Context – Drinking Water Northumbrian Water Ltd are licensed to abstract ground water from a number of boreholes drilled into the aquifer beneath the study area. NWL pumping station abstracts enough drinking water to supply ~30,000 residents in the Sunderland area. Fulwell GWS Extent of Aquifer

Deep Coastal Mine Shaft Abstraction of Ground Water Limestone Aquifer Carboniferous Coal Measures North Sea Context – Rising Mine Water Impact on Aquifer Rising mine water Polluting mine water

The resultant ochreous mine water has a distinctive orange colour and can cause unwanted pollution to receiving waters. The mine water within the workings is very saline – as salty as sea water. Context – Mine water

Context - Mine Water Monitoring The Coal Authority predicts that mine water levels could reach sea level in Jan 2018, at which point the overlying aquifer will be at risk of pollution from the saline and ochreous mine water. 6

Site Identification The Coal Authority’s aim is to start pumping out the mine water at a rate that will stop the rise in mine water at a ‘control level’ below the base of the aquifer. Access into the mine workings for pumping is best achieved at or close to former colliery shafts Three former colliery sites have been identified where good connectivity to the mine workings is feasible. Westoe Whitburn Wearmouth Inland extent of Mining Block

Previous Investigations Small scale pumping trial at Westoe Colliery Crown Shaft Key findings: Max. allowable abstraction rate had no impact on mine water levels. A second, larger scale trial was subsequently proposed Larger scale pumping trial was carried out over 3-month period from a new borehole drilled into the old Whitburn Colliery workings. Key findings: At an abstraction rate of 10l/s, the mine water levels: dropped at Whitburn held steady at Westoe slowed to half original rate at Wearmouth and Boldon. The mine water chemistry was established No ochreous staining was observed beyond 10m from discharge point.

9 Previous Investigations OUTCOME Hydrogeological findings from these trials led to the confirmation of three sites where abstraction could potentially control mine water levels across the mining block: Westoe Colliery Crown Shaft Whitburn - Coastal Park Wearmouth - Stadium of Light

Site Assessment As part of the Coal Authority’s Feasibility Study, meetings and discussions have been held with key stakeholders to review options and proposals. Consultees:South Tyneside Council Sunderland City Council Environment Agency Natural England National Trust Northumbrian Water A comparative site assessment has been compiled, addressing the key feasibility issues relevant to development of this scheme

Westoe Colliery Crown Shaft 11 Trow Quarry Trow Lea Gypsies Green Recreation Ground Trow Point Westoe Crown Village Westoe Crown Shaft & Compound WESTOE Graham’s Sand Sandhaven Beach Coast Road A183 The Leas Directionally-drilled gravity sea outfall Pumping main Site rejected because: Access shaft located within new residential development Long-term shaft maintenance required Long pumping main required to reach sea outfall Discharge adjacent to popular bathing beach Significant impact on high amenity area anticipated if future treatment is required The Site The Proposed Works

Wearmouth - Stadium of Light 12 Keir Hardy Way Wear Estuary Stadium of Light Steep bank Aquatic Centre Restricted access to mine water via existing capped shafts Site rejected because: Very deep borehole required close to high amenity sites Outfall construction difficult Discharge into tidal estuary – poor dispersion All suitable adjacent land identified in UDP – no land if future treatment is required New borehole and Headworks Directionally-drilled gravity estuary outfall Diffuser The Site The Proposed Works

Whitburn Coastal Park 13 The Wherry Souter Lighthouse Mill Lane A183 Whitburn Coastal Park Coastal Path New Headworks at existing borehole Gravity discharge pipe in trench Directionally-drilled gravity sea outfall Diffuser Site selected because: Existing borehole proven to control mine water levels the across mining block Pump Test results give high confidence of scheme success Sampling test results showed minimal impact on coastal environment Outfall sufficiently remote from bathing beaches Good mine water dispersion predicted in vigorous sea conditions Site suitably distant from residential properties Suitable adjacent land if future treatment is required The Site The Proposed Works

Regulation The proposed discharge of mine water to the sea will require the Coal Authority to apply for a Permit to Discharge from the Environment Agency The EA will consult with a range of environmental organisations before making a decision on approval of the application.

Preferred Solution Extended pump test at Whitburn Coastal Park Pumped abstraction of mine water from existing borehole and gravity discharge to sea via new outfall off The Wherry. It is anticipated that discharge of the untreated mine water will be initiated at 10l/s with levels across the mining block being continuously monitored over a 12 month period Regular sampling and testing of the mine water and the receiving coastal waters will be implemented to check compliance.

Preliminary Project Programme October 2012 to July Surveys, negotiations and applications for Licenses, Approvals and Permits October 2012 to December Concept and Detailed Design February 2014 to December Construction January 2015 to December Monitoring and Sampling/Testing July 2015 to December Data review and additional design work if required.

Questions are invited