7.
Geology and Hydrogeology
7.8
Resources
7.8.1
Aquifers
Consolidated
Sediments (Bedrock)
The
main bedrock aquifers identified are:
- Sandstone
aquifer of the Kiltorcan formation. This formation may contain
aquifers of regional importance.
- Karstified
limestone: Ballyadams formation. This formation contains
an aquifer of regional importance. A large spring located
in the south of Paulstown is the source for a regional water
supply in a part of Co Kilkenny.
- Dolomitised
limestones, Waulsortian and Butlersgrove formations. A substantial
part of this aquifer drains in the River Nore. This aquifer
has been developed for industrial water supply in Carlow
town and for municipal supply in Bagenalstown.
- Ballysteen
Formation: can contain aquifers of regional importance (3).
- Ballymartin
Formation: only contains aquifers of minor importance (3).
- Maulin
Formation: These rocks contain only minor aquifers (3).
The constraints to route selection posed by bedrock aquifers
are not likely to be as significant as sand and gravel aquifers,
so they have not been plotted on the geotechnical constraints
maps.
Unconsolidated
Sediments (sands and gravels)
There
is a thick deposit, mainly of sand and gravel, which occurs
in the constraints study area as follows:
-
Major aquifer along the River Nore south of Kilkenny city
(10 m to 30 m), designated G-3.
- Other
gravel aquifers identifed stretching along the main rivers
occurring in the constraints study area are considered to
be minor aquifers (5).
Aquifer Vulnerability and Protection
Draft
groundwater vulnerability mapping was provided for County
Kilkenny by the GSI. The data available was examined to identify
any major vulnerable aquifers occurring within the constraints
study area. Some extremely vulnerable aquifers were reported
in areas where the shallow rocks lay within 0 m to 3 m from
the surface as follows:
-
Rock aquifer between Thomastown and Kilmacow
- Rock
aquifer between the north-east of Thomastown and Dungavan
- Rock
aquifer at the north-east and north-west of Gowran.
Where the water table would be lowered as a result of excavation
for road cutting, the potential effects on local wells would
need to be assessed. Lowering of the water table, potentially
could reduce or eliminate the well yields.
Road drainage as well as accidental spillages could also potentially
have an impact on the quality of the local groundwater. In
areas of road crossings through zones of high aquifer vulnerability,
specific design measures for road drainage may be required
to prevent surface activity from polluting the underlying
groundwater.
7.8.2
Mineral Resources
There are numerous active and disused sand and gravel pits
within the constraints study area, many of which are identified
on the geotechnical constraints figures. The locations of
rock quarries identified on the GSI maps, which are fewer
in number are also shown on the geotechnical constraints figures.
Some of these pits and quarries may also provide a source
for road construction materials.
As specific routes could impact on the viability of open cast
mining, the potential for mineral resources along specific
routes will be considered at route selection stage. It may
be possible to identify these potential mineral resource areas
in consultation with the Department of the Marine and Natural
Resources, the County Councils, as well as the minerals section
of the GSI.
The only mine identified in the constraints study area was
an active dolomite mine near Bennettsbridge.
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