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Protection of the Citys Public Water Supply and the Aquifer Resource - PowerPoint PPT Presentation

City of Meridian Public Works Department Protection of the Citys Public Water Supply and the Aquifer Resource Meridian Public Works Primary Responsibilities Water Supply and Wastewater Treatment The mission of Public Works is to


  1. City of Meridian Public Works Department Protection of the City’s Public Water Supply and the Aquifer Resource

  2. Meridian Public Works • Primary Responsibilities – Water Supply and Wastewater Treatment – The mission of Public Works is to anticipate, plan and provide exemplary public services and facilities that support the needs of our growing community in an efficient, customer-focused and financially responsible manner. • Water Supply – Ensure an adequate supply of clean, safe, drinking water is available for all current and future residents.

  3. Water Supply • City Water Supply – Over 90,000 residents and growing fast – Groundwater diverted from 23 wells – 3.5 billion gallons pumped in 2015 – Future demand may approach 15 billion gallons per year – Is the resource sustainable? • Quantity • Quality

  4. Water Quantity • Where do we get data? – Test wells – Up to 20 years of ground Test Test water level monitoring Water Well Well Table • What does the data show? – Aquifer system includes many different layers – Aquifer system is full and robustly recharged – Water supply is sustainable • City actions – Continue to monitor water levels

  5. Water Quality Regulated by Safe Drinking • Water Act Where do we get data? • Test Test – Knowledge of land use and Water history Well Well Table – Water quality sampling from supply wells and monitoring Nitrate, Herbicides wells from multiple depths What does the data show? • – Human-introduced contaminants exist in some layers – Natural contaminants exist in some layers – Water chemistry and temperature varies with depth

  6. Water Quality Concerns and Strategies Potential Contaminant 1. Existing Paths contaminants Water Sealed • Build test wells Table Well • Seal wells • Pumping rates • Water Treatment Sealed wells are 2. Introduction of protected from contaminants future contaminants • Ordinances • Monitoring

  7. Water Quality Concerns and Strategies Potential Contaminant Paths 3. Disruption of natural barriers Unsealed Water Well Sealed Table Well to contaminant movement – Actions: Sealed wells are protected from • Maintain natural contaminants protective layers Unsealed well when building casings allow contaminants new wells to travel vertically

  8. Primary Water Quality Concern Well Casing • Unsealed domestic wells – “Drill and Drive” Open construction methods “Unsealed” Annular Space – Data collected from well Drive Shoe abandonments prove that voids exist outside casings “Drill and Drive” Drive shoe is larger than casing

  9. Protection Strategy Well Casing • Alternate drilling method – Mud-rotary drilling Tremie Pipe Drill Bit – Full-depth casing seals Drilling Mud Full-depth well seal Mud- rotary drilling

  10. Request for Area of Drilling Concern • Submitted to IDWR • Documents: – Aquifer characteristics – Presence of contaminants of concern – Unsealed nature of “drill and drive” wells • Proposes and suggest rules to: – Protect the groundwater resource from contamination and waste – Protect public health

  11. Conclusion • The water resource belongs to everyone and everyone is responsible for protecting it

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