Full Report - Sustainable Aggregates

CR/07/042N
The results of the drilling show a chalky glacial till to bedrock. This indicates one of two
scenarios. Either the sand and gravel is of variable thickness beneath the overlying till, or it was
deposited on top of the till and is within depressions in the till surface.
• BH7 [468628 298200]
BH6 was drilled approximately 150m from an outcrop of sand and gravel, and was drilled to
assess how continuous the deposit is beneath the glacial till.
The borehole discovered no sand and gravel, consisting of variable glacial till. This suggests that
the sand and gravel has a variable thickness beneath the till, or the deposit has been eroded and
so is only present in patches.
• BH8 [468900 295446]
Borehole 8 was drilled within a sand and gravel deposit approximately 0.5km long and 150m
wide, surrounded by glacial till. There was no existing PSA data for this deposit.
The borehole revealed slightly gravelly, very clayey SAND at 1.4-2.5m. It had a silt/clay content
of 26% and an overburden to mineral ratio within this borehole of 1.3:1. Made Ground was
recorded at th top of the borehole overlying the sand, and a firm till was recorded beneath to the
terminal depth of the borehole (18.75m). This would suggest that the pocket of sand and gravel
overlies the glacial till, and is therefore unlikely to be widespread.
• BH9 [471681 294153]
BH9 was drilled within a region of glacial till, with an aim of investigating the presence or
absence of an underlying glacial sand and gravel.
The results of the borehole suggest there is no underlying sand and gravel, with glacial till
recorded for the total borehole depth of 13m.
• BH10 [494064 293968]
BH10 was drilled in an area of glacial till, with sand and gravel mapped beneath it and
outcropping within approximately 100m. The location was chosen to confirm the relationship
between the two deposits, and gain PSA data for the sand and gravel.
The borehole revealed a clayey very gravely SAND at 2.4m, which had a depth of 1.1m. It had a
low silt/clay content of 16% and was 51% sand. The overburden to mineral ratio at this location
was 2.2:1.
• BH11a [459662 289360]
BH10 was drilled in an area of glacial till, with sand and gravel mapped beneath it and
outcropping approximately 1.5km away. The location was chosen to confirm the relationship
between the two deposits, to build an understanding of the distribution of the sand and gravel,
and gain PSA data for the sand and gravel.
The borehole identified no sand and gravel. The total depth of the borehole was 19m, indicating
that the sand and gravel is not continuous beneath the till.
• BH11b [457864 287578]
BH10 was drilled in an area of glacial till, with sand and gravel mapped beneath it and
outcropping within approximately 100m. The location was chosen to confirm the relationship
between the two deposits, and gain PSA data for the sand and gravel.
BH11b identified a thin deposit of clayey very sandy GRAVEL, at 7-7.8m. The deposit had a
small silt/clay content of 6%, and contained 41% sand. The overburden to mineral ratio for this
deposit is almost 9:1 at this location. The borehole demonstrated that glacial till is deposited
above and below this gravel.
155