Geology and hydrogeology ... …
Report No. SRL/FP/004.1 (10/05/2006)
APPENDIX 1: POSTSCRIPT
This appendix provides an account of information recently acquired by the author relating to three unsolved problems:-
On whether or not the Kimmeridge Clay in Lake E at Radley is suitable for large- scale bunding (sealing) the toxic contents,
A recollection of the previous owner30 that a significant amount of Kimmeridge Clay was removed mainly from the western part of Lake E to be used at Farmoor reservoir some years ago, making that area of Lake E the deepest part of the lake31. Also there is the
possibility of Radley, they
the existence of springs at could be associated with risk
Radley (see below).
are springs at of clay in each
bunded lake and/or the side lining. under any sealed lake exceeds that
The problem with springs is of the groundwater, there will
that, if water pressure inevitably be a reverse
flow from the spring into the groundwater. If that happens underneath or bunded lake, then the seal must be in doubt. If a spring exists then the integrity of the clay bund to any existing or planned PFA dump at Radley is
very close-by a question of the raised.
On whether or not Lake F will drain if and when Lake E is drained for at least 5 months The previous owner, Mr CW Drysdale, has claimed, in a letter to the local press32, that, when he drained Lake E for a number of weeks, some years ago, to remove the fish stock, there was no affect on Lake F. Mr Drysdale said he did not pump the water into Lake F when he drained Lake E. When questioned on this by the author and asked what exactly happened to the level of water in Lake F, he offered no direct knowledge, merely saying that there was no complaint from the "angling alliance" so there can have been no
problem. He said that the weather was
recollections in the community. drained, it was pumped into Lake
Mr R F and
fine at the time. However there seem to be other Faulkner has recorded that, when Lake E was then out to local drainage channels leading to the
River Thames. Some anglers and walkers who same story. However there appear to be two d r a i n i n g L a k e E . O n e i s t h a t i t w a s t o r e m o v e frequent the lakes appear to recollect the stories circulating about the purpose for the fish stock, in about 1990 or 1991, a v a r i o u s e y e w i t n e s s e s 3 3 a n d g r a v e l f r o m L a k e E 3 4 , w h i c h story supported by the anglers, Another is that it was drained to the walker, drywork the Mr was Drysdale. originally
wet-worked. Nothing there ever was dry working and, to bear
in my conversation with Mr Drysdale can be used to confirm that working; Mr Drysdale concentrated entirely on the history of wet this out, he noted that the large number of islands in Lake E would
not be still there had it worked through35. So
been dry-worked, because then the islands could easily have we have two questions. Was there more than one draining of
30 Drysdale C W, pers. comm.
31 Jarvis Associates (1992). See Guyoncourt D M M, Save Radley Lakes report SRL/WE/005.1, p.6.
32 Drysdale C W, letter published in The Herald, 28 April 2006
33 One observer at the time (Dr R Eeles) reports that the fish were removed over several weeks. After the fish were removed the lake
was allowed to fill without any gravel extraction at all.
34 ES, page 24
35 These islands are of sand and gravel (and are surrounded by very shallow water) where lithification has started (cementing of the
stones), a process which can be initiated by the presence of e.g. calcium and iron salts. It was common practice for Messrs Curtis to leave these islands and shallows so gravel around them was wet worked. Visual inspection on a visit to a number of these islands indicates that iron salts are copious and the sand/gravel is cementateous. There is no observational evidence to support the suggestion that dryworking ever occurred.
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© SAVE RADLEY LAKES 2006