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Geology and hydrogeology ... …

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

the impurities, heavy metals and other dangerous substances, which are dissolved from the fly-ash. RWE npower, in an unsupported statement “consider that the clay layer is 30 metres thick”. Evidence is presented here to show that it is probably much thinner. Three types of imperfection in the clay are discussed. Failure of the clay seal around H and I, and, if proceeded with, Lake E, will lead to leaching of dangerous substances into the ground water in the river terrace gravels. This groundwater is stated by RWE npower to be deflected towards the west (i.e. towards housing close by, and on the edge of

Abingdon.

Deflection of potentially

water from the accumulating that

H/I. Bunding problem.

of

ground will have the groundwater is Lake E and filling

contaminated groundwater towards potentially serious consequences.

those drawing Evidence is

already contaminated to the south and west of Lakes it with fly ash can only add to this environmental

RWE npower present their hydrogeological and geological arguments on the basis of very little evidence. Before any permissions to proceed with their proposal are given, they must be required to substantiate the many conjectures in their assessment and to determine the integrity of the bunds around H/I by measuring the leach rate into surrounding

groundwater. measurement, lakes.

A possible method is proposed herein. and show that no leakage is occurring, before

They should make this building any more bunded

Finally, I draw attention to a number of pieces of extremely sloppy writing found in Appendix 7 of the RWE npower ES1, the chapter on flooding. There are indications of sloppy thinking, as well as writing. This casual, careless and unprofessional approach leads them to make many dangerous and unsupported statements. These include the following key-points, but the reader is referred to the review, later in this document, of the overall lack of conviction of this significant contribution to the ES.

  • Restoration levels of Lakes H/I, are shown to be too high. This will take volume out of the floodplain in two ways (a) by occupying it and (b) by blocking access to fluvial water from the Thames from spreading northwards towards and across the disused railway track, so allowing the area in the vicinity of Lakes E and F to contribute their large surface area to the floodplain. The County Council and the Environment Agency should think again about the risk they would be taking if the proposed restoration for Lakes H/I were to be allowed.

  • The small volume of the drainage ditch proposed to remove groundwater blocked by the bunding on Lake E is shown to be too small to matter, but the continued insistence by RWE npower shows that they secretly believe that Lake E is in the floodplain, even though they say that it is not.

  • Incorrect estimates of groundwater flow have been made, understating the flow by an order of magnitude or two.

In a postscript (Appendix 1) written after the main document, I examine the likelihood of springs, associated with faulting, occurring within the Kimmeridge Clay. Many such springs are known to occur, and evidence of their presence under gravel may not necessarily be visible at the surface as the spring would typically flow directly into the gravel and the flow would remain underground. However, if springs were to occur at the base of a PFA lake subject to sealing by clay, then this would have important implications for the long term integrity of those seals; and, if the springs were (eventually, if not initially) able to penetrate to the lake contents, for the ability of those contents to consolidate and stabilise. Although very much an afterthought, this may well be the most serious risk associated with the proposed PFA disposal method at Radley, and carries with it many worrying implications

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© SAVE RADLEY LAKES 2006

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