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Geology and hydrogeology ... …

Report No. SRL/FP/004.1 (10/05/2006)


A summary report prepared by P J Harbour M.A., Ph.D., revised and edited by B J B Crowley D.Phil., C.Phys., F.Inst.P. with corrections and additional material by R M G Eeles B.Sc., Ph.D.


The in situ Kimmeridge Clay at Radley has been assumed thick and impervious, suitable for bunding lakes used as dumps for waste PFA, which contains soluble heavy metals. It is probably not thick and will probably not be impervious. The clay seals deflect groundwater towards Abingdon, where people are drawing on this groundwater for their gardens and ponds. Lakes H/I, already bunded with Kimmeridge Clay, may now be leaching metals and toxins into the groundwater. If permission is given for dumping PFA waste into Lake E at Radley, the bunding seal will fail. Permission should be refused.

The restoration plans for Lakes H/I, apparently agreed by the Environment Agency, will remove volume from the floodplain, both because of excess material and because the restored levels are too high to allow floodwater to access the area north of the disused railways track. The Environment Agency should be required to approve any finally agreed restoration levels and asked to make a plan to mitigate for the loss of floodplain that may already have been consented to.

A possible method of measuring the leach rate from Lakes H/I is proposed. RWE npower should be required to investigate this leach rate before any more dumping of fly ash is permitted in the floodplain at Radley, or indeed elsewhere.

The geological integrity of the Kimmeridge Clay layer is examined and it is found that there is a likelihood of springs associated with faulting. The presence of springs under the clay seals, even if initially prevented from entering the lake, would quite quickly undermine the seals by erosion and cause them to fail.


This report looks at the Hydrological, Hydrogeological and Geological aspects of the Planning Application by RWE Npower1 to fill Lake E at Radley with Pulverised Fuel Ash and concludes that there is strong evidence that the site is fundamentally unsuitable for this type of disposal within the terms the existing Groundwater Regulations, which did not apply when conditional planning permission was first granted in 19822. Whilst Save Radley Lakes has looked at pollution risks3 associated with the disposal of PFA slurry and has found evidence4 for groundwater pollution around Lake H/I, arguments relating to the causative aspects of this pollution have hitherto not been fully developed.

The in situ clay (Kimmeridge Clay), which RWE npower propose to use to seal the bunds around and under Lake E at Radley, may not be of sufficient quantity or quality to retain

1 RWE npower, Planning Application dated 31 January 2006, submitted to Oxfordshire County Council. The principal document

comprising this application is the Environmental Statement (ENV/057/2006) herein referred to as the ES.

2 Oxfordshire County Council, Conditional Planning Permission SUT/RAD/5948 (February 1982). This Permission was later superseded

by Conditional Planning Permission SUT/RAD/5948/12-CM (February 2002) which is essentially unchanged insofar as it applies to phase 2 operations.

3 Guyoncourt D M M , Crowley B J B and Eeles R M G, Pollution Risks Associated with the Deposition of PFA Slurry into the Radley

Lakes, Save Radley Lakes report SRL/FP/002.2 (April 2006)

4 Eeles R M G, Evidence of Ground- and Surface-Water Pollution Due to the Disposal of PFA at Radley, Save Radley Lakes report

SRL/FP/003.1 (April 2006)

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