Water Framework Directive. Groundwater Monitoring Programme. Site Information. New Inn

Transcription

1 Water Framework Directive Groundwater Monitoring Programme Site Information New Inn ImagePath1: New Inn\New_Inn_pump_house_a_(8 00_x_600).jpg The water sampled at New Inn represents pumping from 4 different wells which produce an average of 550 m³/d in total. Wellhead protection is poor which might affect water quality results. An investigation is recommended. August 2011

2 Site Name: RBD: Site Use: New Inn WRBD Easting: Northing: Drinking Water (GWS) Hydrometric Area: 30 Townland: Ownership: Water Quality Monitoring Network: CASTLEBIN SOUTH New Inn Group Water Scheme SITE INFORMATION County: EU Reporting Code: GWB Name: GWB Code: Drinking Water Code: Water Level Monitoring Network: IE_WE_G_0007_07_018 Loughrea IE_WE_G_ PRI7451 Several wells housed inside small below-ground vaults/chambers in the general parking area of the local GAA club and field. Level Surveillance Operational (Point) Operational (Diffuse) Y N Y N Flow N Site Comments: Location and Access Information: SITE DIRECTIONS Located in the village of New Inn, immediately behind (NW of) the GAA building. Additional Comments: Poor wellhead protection is a theme for the site. Monitoring Point Type: Borehole Log Available: Top of Casing (m agl): Borehole Y -0.6 WELL INFORMATION Abstraction Rate (m³/d): 600 Ground Elevation (m OD): 85 Total Drilled Depth (m bgl): 12.2 Depth to Bedrock (m bgl): 7 Upper Casing Diameter (mm): 200 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: New Inn GWS Screen Type (PVC,Steel,other): Comments on Monitoring Site: Number of Abstraction Points in the Scheme: PVC Screen Slot Size (mm): 2 Grouted above (m bgl): Grout Volume Injected (m³): 2-12 Gravel Pack Volume (m³): Open Hole Interval (m bgl): Eight production wells have been drilled in total between the late 1970s to One well, original well BH1, has been decommissioned. The three most recently drilled wells, PW1, PW2, and PW3, stand idle. Four wells are currently producing water, PW4, PW5, PW6, and PW7. PW7 is the main well, producing about 30 m³/hr for hours each day. PW4, PW5 and PW6 produce approximately 12 m³/hr in total and are pumped less. Water is pumped to the onsite reservoir, where the collective water can be sampled pre-treatment at the inflow. The well details above are for 7 Source Report Available N Scheme Summary: Scheme consists of 7 wells, of which 4 produce water. Water is pumped from each well to a nearby reservoir where water is chlorinated and pumped to distribution network. The GWS is operated by TSSL Ltd from Athenry. Page 2 of 5

3 HYDROGEOLOGY GEOLOGY Soil: Subsoil: Bedrock: Made/Built land (Made) n.a. (Made) Sand and Gravel Subsoil Permeability: Low HYDROGEOLOGY ZONE OF CONTRIBUTION Aquifer Category: Estimated ZOC Size (km): ZOC Delineation Comments: Vulnerability Ll at Monitoring Low Flow Regime: Sand and site: Gravel 0.72 ZOC Delineated By: CDM (HM) with D. Ball Recharge Est Recharge (mm/yr): Estimate (mm/yr): The New Inn wells pump water from sands and gravels at the margins of an esker which runs roughly SW-NE through the village to the east of the site. The ZOC is delineated on the basis of a recharge estimate (300 mm/yr), topography, geometry of esker sand and gravel deposits, and the abstracted volume (max. 600 m³/d). The ZOC has been reviewed "in principle" by David Ball on the basis of his knowledge of the site. 300 Groundwater Vulnerability within ZOC (% area): Extreme (X) 2.98 Extreme (E) 0 High Moderate 5.24 Low High to Low 0 Unclassified 0 Hydrochemical Signature: Alkalinity (mg/l HCO3): Hardness (mg/l CaCO3): Conductivity (us/cm): Monitoring Record Period: Pressure (e.g., Nitrates, Phosphates, Abstractions): Average: 331 Average: 369 Average: 710 From: 1995 Ca-HCO3 Diffuse Range: Range: Range: To: 2010 HYDROCHEMISTRY Additional Water Chemistry Information: RISK ASSESSMENT Typical Contaminants: During the monitoring period: The average nitrate concentration was 12 mg/l NO3 and the maximum nitrate concentration was 27 mg/l NO3. The average ammonium concentration was mg/l N and the maximum ammonium concentration was 0.23 mg/l N. The average molybdate reductive phosphorus (MRP) concentration was 0.05 mg/l P and the maximum MRP concentration was mg/l P. The average chloride concentration was 24.6 mg/l Cl and the maximum chloride concentration was 33 mg/l Cl. Nitrates Risk Category: Not at risk, low confidence GWB Status: Good Impact Potential within ZOC (% area): Extreme: 0.00 High: 1.83 Moderate: Low: Negligible: OTHER INFORMATION The New Inn GWS has a long history with many changes and additions. Several investigators have been involved in its development, most recently by David Ball (since 1995/96). A good summary of GWS history is provided in reports by David Ball in 1999 and A formal SPZ report has not been prepared by the GSI or other, however, the site characteristics are well understood and a ZOC can be delineated with reasonable confidence. One item of note - the wellhead completions at PW4 through 7 are poor. These sit in below ground vaults and respective casings are nearly flush to the vault floors. On the day of the site visit, standing water was observed inside each vault, with direct ingress of surface water observed in PW4 and PW7. The best protected wells, PW1, PW2 and PW3 are not used. According to the caretaker, they have "poor yields", "high drawdowns", and "high ammonia concentrations". It is recommended this be looked at by the EPA. Page 3 of 5

4 Pump House Well Head (BH7) Direct Ingress to Well (BH4) Page 4 of 5

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 Lm Ll, PI 225 m 150 m 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: Version 1: Version 2: Version 3: Version 4: Prepared by Date: Prepared by CDM (HM) Date: Feb 2011 Prepared by Date: Prepared by Date: Prepared by Date: Page 5 of 5

6 !. / IE_WE_G_0007_018 Sligo Sligo Leitrim Longford Laois Location Map for New Inn BasinDistrict km

7 !. Ll / IE_WE_G_0007_018 Sligo Leitrim Aquifer Category for New Inn Ll k

8 !. / IE_WE_G_0007_018 Sligo Leitrim Bedrock Map for New Inn Dinantian Upper Impure Limestones km

9 !. / IE_WE_G_0007_018 Sligo Leitrim Groundwater Vulnerability for New Inn E (Extreme) M (Moderate) H (High) E (Rock near surface or Karst) L (Low) km

10 !. / IE_WE_G_0007_018 Sligo Leitrim Subsoils Map for New Inn Cutover raised peat Gravels derived from limestones Lacustrine sediments Made ground Bedrock outcrop or subcrop Till derived from limestones km

11 !. / IE_WE_G_0007_018 Sligo Leitrim Soils Map for New Inn Basic Deep Well Drained Mineral Basic Deep Poorly Drained Mineral Basic Shallow Well Drained Mineral Basic Shallow Poorly Drained Mineral Cutover/Cutaway Peat Lacustrine Basic Poorly Drained Peaty Mineral Basic Shallow Poorly Drained Peaty Mineral Made km