Knock Airport

Water Framework Directive
Groundwater Monitoring Programme
Site Information
Knock Airport
ImagePath1: Knock
Airport\KnockAirport_A_Site_s.jp
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This site is a disused sand and gravel quarry in which rainwater and
groundwater collects and from which approximately 40-60 m³/d is
pumped (via a pump lowered inside a concrete caisson). The source is
essentially a groundwater seep into an excavated pit.
August 2011
Mayo
SITE INFORMATION
Site Name:
Knock Airport
County:
Mayo
RBD:
WRBD
EU Reporting Code:
---
Easting:
144869
GWB Name:
Moy SG
Northing:
297475
GWB Code:
IE_WE_G_0064
Site Use:
Drinking Water (PWS)
Drinking Water Code:
Hydrometric Area:
34
Water Level
Monitoring Network:
Townland:
Barnalyra
Ownership:
Knock Airport
Surveillance
Water Quality
Monitoring Network:
2200PUB1036
Level
Flow
N
N
Operational (Point)
N
Operational (Diffuse)
N
N
Site is located within a disused sand and gravel quarry pit surrounded by agricultural land.
Site Comments:
SITE DIRECTIONS
Location and Access
Information:
Take the N5 west from Charlestown. Take the first left onto a third class road and drive south for about 4.5km. Then take a
left hand turn (look out for a sign pointing to sand and gravel pits). The site is about 300m down this road on the left hand
side.
Additional Comments: ---
WELL INFORMATION
Monitoring Point Type:
Spring
Abstraction Rate (m³/d):
40
Ground Elevation (m OD):
129
Borehole Log Available:
---
Total Drilled Depth (m bgl):
n/a
Depth to Bedrock (m bgl):
---
---
Upper Casing Diameter
(mm):
---
Lower Casing Diameter
(mm):
---
Final Borehole Depth (m):
---
Upper Casing Bottom
Depth (m bgl) :
---
Lower Casing Bottom
Depth (m bgl):
---
Screen Interval (m bgl):
---
Screen Type
(PVC,Steel,other):
---
Screen Slot Size (mm):
---
Grout Type
(cement,bentonite):
---
Grouted above (m bgl):
---
Grout Volume Injected
(m³):
Gravel Pack Interval (m
bgl):
---
Gravel Pack Volume (m³):
---
Potential Yield (m³/day):
---
Specific Capacity
(m³/d/m):
---
Static Water Level (m bgl):
---
Scheme Name:
Knock Airport
Number of Abstraction
Points in the Scheme:
1
Top of Casing (m agl):
Source Report Info:
Scheme Summary:
---
--Open Hole Interval (m
bgl):
This site is a former sand and gravel pit that was active until 1984. It
has served as the water supply for Knock Airport since then. The
water in the pit is essentially a groundwater seep ("spring") whereby
Comments on Monitoring the water in the pit is a representation of the groundwater table in the
surrounding sand and gravel aquifer (which is higher than the
Site:
excavated depth of the pit). The standing water in the pit therefore
represents groundwater, plus rainwater. Water is pumped from a 1-m
diameter concrete caisson which sits approximately 2 m down on the
pit floor. A pump has been fitted inside the caisson.
Source Report
Available
N
---
The scheme consist of a pool of water which collects naturally in a disused gravel pit. Water is then pumped to Knock
Airport from a 2 m deep concrete caisson structure in which the pump sits. A small quantity of water is also gravity fed to
nearby homes.
Page 2 of 5
HYDROGEOLOGY
GEOLOGY
HYDROGEOLOGY
Soil:
Poorly drained mineral soils with peaty topsoil (BminSPPT)
Subsoil:
Glaciofluvial sands and gravels (GLs)
Bedrock:
Sand and gravel
Aquifer
Category:
Estimated
ZOC Size
(km²):
ZONE OF
CONTRIBUTION
ZOC
Delineation
Comments:
Groundwater
Vulnerability within
ZOC (% area):
Rkc
Vulnerability
at Monitoring
site:
0.04
ZOC
Delineated By:
Subsoil
Permeability:
High
High to Low
Flow Regime:
Sand and
gravel
CDM (HM)
Recharge Est
Recharge
(mm/yr):
Estimate
(mm/yr):
800
The disused pit with standing water is likely a "throughflow" pit, as groundwater in the sand and gravel aquifer
flows naturally from higher ground in the south to lower ground in the north. The ZOC delineated is based on
a recharge estimate, topography and the total estimated volume abstracted. The latter was increased by 50%
as the sand and gravel aquifer is expected to be able to produce a higher quantity of water (if pumped
harder). Some small (but unknown) quantity of water is also gravity fed to nearby homes, so 20 m³/d was
ascribed to the total abstraction rate to account for this purpose. The total abstraction rate used in the ZOC
delineation is therefore (40 m³/d x 150%) + 20 m³/d = 80 m³/d.
Extreme (X)
Extreme (E)
High
Moderate
Low
High to Low
Unclassified
0
0
0
0
0
100
0
HYDROCHEMISTRY
Few data are available.
Hydrochemical
Signature:
Alkalinity (mg/l HCO3):
Hardness (mg/l
CaCO3):
Conductivity (uS/cm):
---
Average:
Range:
---
---
Average:
Range:
---
---
Average:
Range:
398
389-406
Monitoring Record
Period:
Additional
Water
Chemistry
Information:
From:
To:
2007
2007
RISK ASSESSMENT
Pressure (e.g., Nitrates,
Phosphates, Abstractions):
Phosphates
Typical Contaminants:
---
Risk Category:
At risk, high confidence
GWB Status:
Good
Impact Potential within ZOC (%
area):
Extreme:
High:
Moderate:
Low:
Negligible:
0.00
0.00
0.00
79.88
20.12
OTHER INFORMATION
Water is chlorinated using conchlor liquid. The sampling tap is after chlorination. Untreated water can be sampled from the caisson.
Page 3 of 5
Site Overview
Gravel Pit
Well Head
Page 4 of 5
Data Summary Sheet - July 2011
Disclaimer: The data in this document are based on the best available information and understanding at time of writing. Neither
the Environmental Protection Agency, nor the individual bodies supplying data for this document and accompanying maps will
be responsible for any loss or damage from the use or interpretation of these data.
Rock Unit Geology Map: GSI, 2009
Aquifer Type Map: GSI, 2009
Groundwater Vulnerability Map: GSI, 2009
Soils & Subsoils Type: Teagasc, 2007
Recharge Map: GSI, 2009
Impact Potential Map: EPA, 2009
Risk Assessment Map: EPA WFD Risk Assessment, 2006
Groundwater Body Status: EPA WFD Status Assessment, 2008
Water Quality Data: EPA WFD Monitoring, 2008
Groundwater Threshold Values
Groundwater threshold values for selected parameters:
Nitrate - General Chemical Test/ Drinking Water Test (37.5 mg/I N03)
Ammonium - Drinking Water Test (0.175 mg/I N) / Surface Water Test (0.065 mg/l N)
Molybdate Reactive Phosphorus (MRP) - Surface Water Test (0.035 mg/I P)
Chloride -Saline/Intrusive Test (24 mg/I) / Drinking Water Test (175 mg/I Cl)
Electrical Conductivity -Saline/Intrusive Test (800 µS/cm) / Drinking Water Test (1,875 µS/cm)
Further information on groundwater threshold values is contained in the Groundwater Regulations (S.I. No.9 of 2010).
General Downgradient Distances
General Downgradient Distances (XL) applied to boreholes sourced in bedrock aquifers are constrained to estimate approximate
limits based on data at the GSl. ln some cases they may be higher or lower depending on local conditions.
Rk, Rkd, Lk
225 m
Lm
150 m
Ll, PI
60 m
It is assumed that groundwater downgradient of a spring cannot flow back up to the spring, however a precautionary 30m buffer
is generally applied which allows for instances where pumping under dry weather periods may induce a drawdown or where the
ground may be sloping toward the spring from the downgradient side.
Version 0:
Prepared by
Date:
Version 1:
Prepared by CDM (HM)
Date:
Version 2:
Prepared by
Date:
Version 3:
Prepared by
Date:
Version 4:
Prepared by
Date:
Feb 2011
Page 5 of 5
145500
²
146000
298500
145000
2200PUB1036
297000
!
.
297500
298000
144500
Leitrim
Sligo
Mayo
)
"
Roscommon
Galway
Location Map for KNOCK AIRPORT
!
.
Abstractions
Zone of Contribution
River
© Ordnance Survey Ireland. All rights reserved.
Licence number EN0059208
0
0.25
0.5
1
km
296500
Donegal
145000
145500
²
298000
Rkc
146000
298500
144500
!
.
297500
Rkc
2200PUB1036
297000
Lg
Pl
Leitrim
Sligo
Mayo
Pl
)
"
Roscommon
Galway
Aquifer Category Map for KNOCK AIRPORT
!
.
Abstractions
Ll
Pl
Zone of Contribution
Lm
Rkc
Lg
Fault
River
© Ordnance Survey Ireland. All rights reserved.
Licence number EN0059208
0
0.25
0.5
1
km
296500
Donegal
145500
²
146000
298500
145000
!
.
297500
298000
144500
2200PUB1036
297000
Lg
Leitrim
Sligo
Mayo
)
"
Roscommon
Galway
Bedrock Map for KNOCK AIRPORT
!
.
Abstractions
Dinantian Pure Bedded Limestones
Ordovician Volcanics
Fault
Lg
Zone of Contribution
River
© Ordnance Survey Ireland. All rights reserved.
Licence number EN0059208
0
0.25
0.5
1
km
296500
Donegal
145500
²
146000
298500
145000
2200PUB1036
297000
!
.
297500
298000
144500
Leitrim
Sligo
Mayo
)
"
Roscommon
Galway
Groundwater Vulnerability Map for KNOCK AIRPORT
!
.
Abstractions
E (Rock near surface or Karst)
M (Moderate)
Water
Zone of Contribution
E (Extreme)
L (Low)
No Data
River
H (High)
HL (unmapped - High to Low)
© Ordnance Survey Ireland. All rights reserved.
Licence number EN0059208
0
0.25
0.5
1
km
296500
Donegal
145500
²
146000
298500
145000
2200PUB1036
297000
!
.
297500
298000
144500
Leitrim
Sligo
Mayo
)
"
Roscommon
Subsoils Map for KNOCK AIRPORT
!
.
Galway
Abstractions
Alluvium
Made ground
Zone of Contribution
Blanket peat
Till derived from Devonian and Carboniferous sandstones
River
Cutover raised peat
Till derived from granites
Gravels derived from Devonian and Carboniferous sandstones
Water
Gravels derived from limestones
© Ordnance Survey Ireland. All rights reserved.
Licence number EN0059208
0
0.25
0.5
1
km
296500
Donegal
²
145500
146000
298500
145000
2200PUB1036
297000
!
.
297500
298000
144500
Leitrim
Sligo
Mayo
)
"
Roscommon
Soils Map for KNOCK AIRPORT
!
.
Galway
Abstractions
Acid Deep Well Drained Mineral
Basic Shallow Well Drained Mineral
Mineral Alluvium
Zone of Contribution
Acid Deep Poorly Drained Mineral
Basic Shallow Poorly Drained Mineral
Made
River
Acid Shallow Well Drained Mineral
Basic Shallow Poorly Drained Peaty Mineral
Water
Acid Shallow Poorly Drained Mineral
Blanket Peat
Acid Shallow/Rocky/Peaty Mineral
© Ordnance Survey Ireland. All rights reserved.
Licence number EN0059208
Cutover/Cutaway Peat
0
0.25
0.5
1
km
296500
Donegal