Report No. SRL/FP/004.1 (10/05/2006)
Geology and Hydrogeology at the Radley Lakes
An Assessment of the Geological and Hydrogeological Suitability of the Radley Lakes for the Disposal of Pulverised Fuel Ash and the Risk of Groundwater Pollution associated with the Planning Application by RWE Npower to fill Lake E
P J Harbour
SUMMARY HYDROGEOLOGICAL REPORT
Save Radley Lakes
Summary: 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.
© SAVE RADLEY LAKES 2006