The Llanfair DC borehole measures groundwater levels in Permo-Triassic Sandstones in the Vale of Clywd.
Our enquiries service can help you to access groundwater level data for this well.
|Datum||83.08 m AOD|
|Monitored by||EA Wales|
The borehole is in the Vale of Clywd, and representative of levels within the important Permo-Triassic Sandstone aquifer.
The borehole is drilled into the Kinnerton Sandstone Formation (Sherwood Sandstone Group) overlain by till deposits. It is possible that the sandstones are in hydraulic continuity with Carboniferous Limestone, which may contribute water to the aquifer.
The observed water levels are within the till, rather than sandstones, implying that the sandstone aquifer is confined.
The well is 121.9 metres deep, lined to 18.59 metres, with a diameter of 248 mm reducing to 146 mm at depth. It was drilled as a purpose built observation well, with a secondary aim of establishing the geological succession.
The driller's log identifies a very porous zone between 98.8 and 100.6 mbgl.
The hydrograph shows a spiky annual sinusoidal pattern, within a relatively restricted range, with fluctuations generally less than 1 metre per annum.
Long-term trends are apparent in the data, with a slow rise through the 1970s, generally falling levels from 1985 to the mid 1990s and a relatively marked increase in levels to a record high in 2002. Since 2002 levels have fallen back slightly and appear to be relatively stable. It is assumed that these fluctuations reflect long-term changes in catchment water balance.
Considered to be good, reliable data.
The borehole was previously numbered SJ15/15.
Contact Andrew McKenzie for further information