Water Framework Directive. Groundwater Monitoring Programme. Site Information. Knock Airport

Transcription

1 Water Framework Directive Groundwater Monitoring Programme Site Information Knock Airport ImagePath1: Knock Airport\KnockAirport_A_Site_s.jp g This site is a disused sand and gravel quarry in which rainwater and groundwater collects and from which approximately 4-6 m³/d is pumped (via a pump lowered inside a concrete caisson). The source is essentially a groundwater seep into an excavated pit. August 211

2 Site Name: RBD: Site Use: Knock Airport WRBD Easting: Northing: Drinking Water (PWS) Hydrometric Area: 34 Townland: Ownership: Water Quality Monitoring Network: Barnalyra Knock Airport SITE INFORMATION County: EU Reporting Code: GWB Name: GWB Code: Drinking Water Code: Water Level Monitoring Network: Level Site is located within a disused sand and gravel quarry pit surrounded by agricultural land. Moy SG IE_WE_G_64 22PUB136 Surveillance Operational (Point) Operational (Diffuse) N N N N Flow N Site Comments: Location and Access Information: SITE DIRECTIONS Take the N5 west from Charlestown. Take the first left onto a third class road and drive south for about 4.5. Then take a left hand turn (look out for a sign pointing to sand and gravel pits). The site is about 3m down this road on the left hand side. Additional Comments: Monitoring Point Type: Borehole Log Available: Spring WELL INFORMATION Abstraction Rate (m³/d): 4 Ground Elevation (m OD): 129 Total Drilled Depth (m bgl): n/a Depth to Bedrock (m bgl): Top of Casing (m agl): 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): Grout Type (cement,bentonite): Gravel Pack Interval (m bgl): Potential Yield (m³/day): Specific Capacity (m³/d/m): Static Water Level (m bgl): Scheme Name: Source Report Info: Knock Airport Screen Type (PVC,Steel,other): Comments on Monitoring Site: Number of Abstraction Points in the Scheme: Screen Slot Size (mm): Grouted above (m bgl): Grout Volume Injected (m³): Gravel Pack Volume (m³): Open Hole Interval (m bgl): This site is a former sand and gravel pit that was active until It has served as the water supply for Knock Airport since then. The water in the pit is essentially a groundwater seep ("spring whereby the water in the pit is a representation of the groundwater table in the surrounding sand and gravel aquifer (which is higher than the 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. 1 Source Report Available N Scheme Summary: 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

3 HYDROGEOLOGY GEOLOGY Soil: Subsoil: Bedrock: Poorly drained mineral soils with peaty topsoil (BminSPPT) Glaciofluvial sands and gravels (GLs) Sand and gravel Subsoil Permeability: High HYDROGEOLOGY ZONE OF CONTRIBUTION Aquifer Category: Estimated ZOC Size (): ZOC Delineation Comments: Vulnerability Rkc at Monitoring High to Low Flow Regime: Sand and site: gravel.4 ZOC Delineated By: CDM (HM) Recharge Est Recharge (mm/yr): Estimate (mm/yr): 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 5% 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 2 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 (4 m³/d x 15%) + 2 m³/d = 8 m³/d. 8 Groundwater Vulnerability within ZOC (% area): Extreme (X) Extreme (E) High Moderate Low High to Low 1 Unclassified Hydrochemical Signature: HYDROCHEMISTRY Few data are available. Alkalinity (mg/l HCO3): Hardness (mg/l CaCO3): Conductivity (us/cm): Monitoring Record Period: Pressure (e.g., Nitrates, Phosphates, Abstractions): Average: Average: Average: 398 From: 27 Phosphates Range: Range: Range: To: 27 Additional Water Chemistry Information: RISK ASSESSMENT Typical Contaminants: Risk Category: At risk, high confidence GWB Status: Good Impact Potential within ZOC (% area): Extreme:. High:. Moderate:. Low: Negligible: 2.12 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

4 Site Overview Gravel Pit Well Head Page 4 of 5

5 Data Summary Sheet - July 211 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, 29 Aquifer Type Map: GSI, 29 Groundwater Vulnerability Map: GSI, 29 Soils & Subsoils Type: Teagasc, 27 Recharge Map: GSI, 29 Impact Potential Map: EPA, 29 Risk Assessment Map: EPA WFD Risk Assessment, 26 Groundwater Body Status: EPA WFD Status Assessment, 28 Water Quality Data: EPA WFD Monitoring, 28 Groundwater Threshold Values Groundwater threshold values for selected parameters: Nitrate - General Chemical Test/ Drinking Water Test (37.5 mg/i N3) Ammonium - Drinking Water Test (.175 mg/i N) / Surface Water Test (.65 mg/l N) Molybdate Reactive Phosphorus (MRP) - Surface Water Test (.35 mg/i P) Chloride -Saline/Intrusive Test (24 mg/i) / Drinking Water Test (175 mg/i Cl) Electrical Conductivity -Saline/Intrusive Test (8 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 21). 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 Lm Ll, PI 225 m 15 m 6 m It is assumed that groundwater downgradient of a spring cannot flow back up to the spring, however a precautionary 3m 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 : Version 1: Version 2: Version 3: Version 4: Prepared by Date: Prepared by CDM (HM) Date: Feb 211 Prepared by Date: Prepared by Date: Prepared by Date: Page 5 of 5

6 !. 22PUB Location Map for KNOCK AIRPORT

7 Rkc Rkc!. Lg 22PUB136 Pl Pl Aquifer Category Map for KNOCK AIRPORT Ll Lm Pl Rkc Lg Fault

8 !. Lg 22PUB Bedrock Map for KNOCK AIRPORT Dinantian Pure Bedded Limestones Ordovician Volcanics Lg Fault

9 !. 22PUB Groundwater Vulnerability Map for KNOCK AIRPORT E (Rock near surface or Karst) E (Extreme) H (High) M (Moderate) L (Low) HL (unmapped - High to Low) Water No Data

10 !. 22PUB Subsoils Map for KNOCK AIRPORT Alluvium Blanket peat Cutover raised peat Gravels derived from Devonian and Carboniferous sandstones Gravels derived from limestones Made ground Till derived from Devonian and Carboniferous sandstones Till derived from granites Water

11 !. 22PUB Soils Map for KNOCK AIRPORT Acid Deep Well Drained Mineral Acid Deep Poorly Drained Mineral Acid Shallow Well Drained Mineral Acid Shallow Poorly Drained Mineral Basic Shallow Well Drained Mineral Basic Shallow Poorly Drained Mineral Basic Shallow Poorly Drained Peaty Mineral Blanket Peat Mineral Alluvium Made Water Acid Shallow/Rocky/Peaty Mineral Cutover/Cutaway Peat