The British Geological Survey map shows that the site in Bretforton lies in an
area of fan gravel over lower lias, mainly clay. The trial pits undertaken
corroborate this.
Groundwater is located in soil pore spaces and voids within rock formation
fractures underground. The depth at which these pores and voids become
saturated is called the water table. Clay soils that are predominant in the
District have very small pore spaces in comparison to gravels; the ability for
groundwater to permeate through clay soil is therefore greatly reduced in
comparison to gravel soils with larger particle composition.
2012 has been officially recorded as the wettest year on record and in this
District the total rainfall exceeded that recorded in 2007. The only ‘relatively
dry spell’ recorded in 2012 was during the months of January, February &
March.
November and December 2012 were two of the wettest months of the year
and despite the fact the level of rainfall experienced was much less intense
than during the 20th & 21st July 2007 event, surface water flooding was
experienced throughout the District on a large scale simply because the
ground was at saturation point.
Taking this into account, it is therefore highly probable that flooding to the
extent witnessed was not previously experienced apart from in July 2007.
The size of the trial hole excavations would not have any subsequent affect
on the movement of groundwater. Only excavated material from the specific
trial hole in question would be placed back in it as backfill, so this can only be
a combination of gravel and clay; groundwater will always find its way
naturally through ground and unless there is a specific spring or seep where
groundwater issues, then the recent flooding was the result of nothing more
than ground at saturation point. Monitoring of groundwater within the trial pits
was undertaken in accordance with national guidelines; unless anything
untoward is discovered during the excavation, there is no need to carry out
long-term monitoring.
The flooding of the property mentioned in 2007 does not compare with the
recent flooding; this undoubtedly flooded as a result of the intensity of rainfall
experienced at the time, as mentioned above.
In conclusion, there is no evidence to suggest that any problem has been
caused during the site investigation, or that the Flood Risk Assessment
submitted is ‘incomplete and flawed’.
M. Cross
28.1.13