Hydrogeologic Investigation & Groundwater Modeling Report

Slides from Presentation at March 16, 2011, Community Meeting (PDF)

Complete Report Documents

For ease of use, the above documents have been broken into smaller sections:

  • Section 1 Introduction (PDF)
    • 1.1 Site Location 1-2
    • 1.2 Environmental Setting 1-2
    • 1.2.1 Climate 1-2
    • 1.2.2 Topography and Drainage 1-2
    • 1.2.3 Hydrogeology 1-3
    • 1.3 Project Scope 1-4
  • Section 2 Hydrogeologic Investigation (PDF)
    • 2.1 Fly Ash Sampling 2-1
    • 2.2 Groundwater and Surface Water Analyses 2-1
    • 2.3 Aquifer Performance Test 2-1
    • 2.4 Investigation Derived Waste 2-2
    • 2.5 Additional Data Sources 2-2
  • Section 3 Hydrogeologic Investigation Results (PDF)
    • 3.1 Site-Specific Geology 3-1
    • 3.2 Groundwater Flow 3-2
    • 3.3 Groundwater and Surface Water Quality 3-2
    • 3.3.1 Initial Data Screening 3-3
    • 3.3.2 Detailed Constituent Analysis 3-4
    • 3.4 Groundwater and Surface Water Conclusions 3-5
    • 3.4.1 Constituent Concentrations 3-5
    • 3.4.2 Constituent Spatial Distributions 3-8
  • Section 4 Groundwater Model Data Review (PDF)
    • 4.1 Modeling Review and Previous Reports 4-1
    • 4.2 Hydrogeologic Data Review 4-2
    • 4.2.1 Aquifer Performance Test Analysis 4-2
  • Section 5 Hydrologic Analysis (PDF)
    • 5.1 Recharge, Drainage and Ponds 5-1
    • 5.2 Leachate Production Rates (HELP Model) 5-3
  • Section 6 Groundwater Flow Model (PDF)
    • 6.1 Model Code 6-1
    • 6.2 Model Domain and Computational Grid 6-2
    • 6.3 Hydrogeologic Layers and Properties 6-2
    • 6.4 Boundary Conditions 6-4
    • 6.4.1 Model Perimeter 6-4
    • 6.4.2 Rivers and Streams 6-4
    • 6.4.3 Agricultural Drainage 6-5
    • 6.4.4 Onsite/Golf Course Ponds 6-5
    • 6.4.5 Recharge and Evapotranspiration 6-6
    • 6.4.6 Groundwater Withdrawals 6-7
    • 6.5 Flow Model Calibration and Sensitivity 6-7
    • 6.5.1 Aquifer Performance Test Transient Calibration 6-7
    • 6.5.2 Steady State Calibration 6-8
    • 6.5.3 Model Sensitivity 6-9
    • 6.6 Simulated Groundwater Flow Field and Water Budget 6-10
  • Section 7 Transport Model (PDF)
    • 7.1 Model Code 7-2
    • 7.2 Input Parameters 7-2
    • 7.2.1 Source Representation 7-2
    • 7.2.2 Transport Parameters 7-7
    • 7.3 Transport Simulations 7-8
    • 7.4 Sensitivity Analysis 7-10
  • Section 8 Conclusions (PDF)
    • 8.1 Current Water Quality Conditions 8-1
    • 8.2 Groundwater Flow 8-1
    • 8.3 Future Water Quality Conditions 8-3
    • 8.3.1 HELP Model Infiltration Rates 8-5
    • 8.3.2 Arsenic Migration 8-6
    • 8.3.3 Nitrate Migration 8-6
    • 8.4 Future Land Use Considerations 8-7
  • Section 9 References (PDF)
    • Figures (PDF)
      • 1-1 Site Location Map
      • 1-2 Site Vicinity Map
      • 1-3 Climate Data
      • 1-4 Generalized Hydrogeologic Section
      • 1-5 Data Collection Locations
      • 3-1 Boring Log Summary
      • 3-2 Surficial Aquifer Sand Zone Structure Contour Map
      • 3-3 Yorktown Confining Zone Structure Contour Map
      • 3-4 Yorktown Aquifer Structure Contour Map
      • 3-5 Surficial Aquifer Potentiometric Surface Map
      • 3-6 Yorktown Aquifer Potentiometric Surface Map
      • 3-7 Constituent Distributions in Groundwater
      • 3-8 Constituent Distribution in Groundwater
      • 4-1 Aquifer Performance Test Well Locations
      • 4-2 MW-3A/MW-3B Observed Water Levels
      • 4-3 PZ-1/PZ-2 Observed Water Levels
      • 4-4 MW-3C Observed Water Levels
      • 4-5 MW-5A/MW-5C Observed Water Levels
      • 4-6 Aquifer System Cross Section
      • 5-1 USGS Stream Flow Gauge Average Stream Flow Values
      • 6-1 Model Domain and Computational Grid
      • 6-2 On-site Model Computational Grid
      • 6-3 Cross-Section AA East-West
      • 6-4 Cross-Section BB North-South
      • 6-5 Land Surface Elevations
      • 6-6 Surficial Aquifer Base Elevation Map
      • 6-7 Yorktown Confining Zone Base Elevation Map
      • 6-8 Yorktown Aquifer Base Elevation Map
      • 6-9 Land Use
      • 6-10 Drainage Ditches
      • 6-11 Golf Course Ponds and Staff Gauge Locations
      • 6-12 Yorktown-Eastover Aquifer Pumping Location
      • 6-13 Aquifer Performance Test Well Locations
      • 6-14 Aquifer Performance Test Simulated and Observed Drawdowns
      • 6-15 Aquifer Performance Drawdown
      • 6-16 Upper Surficial Aquifer - A Wells - APT Model
      • 6-17 Lower Surficial Aquifer - B Wells - APT Model
      • 6-18 Upper Yorktown-Eastover Aquifer - C Wells - APT Model
      • 6-19 Upper Surficial Aquifer - A Wells - High Flow Model
      • 6-20 Lower Surficial Aquifer - B Wells - High Flow Model
      • 6-21 Upper Yorktown-Eastover Aquifer - C Wells - High Flow Model
      • 6-22 Upper Surficial Aquifer Flow Vectors - High Flow Model
      • 6-23 Simulated Head Contours - East-West Cross Section
      • 6-24 Simulated Head Contours - North-South Cross Section
      • 7-1 Ash Fill Emplacement Area
      • 7-2 through 7-9 Simulated Arsenic in Upper Columbia Aquifer
      • 7-10 through 7-13 Simulated Nitrate in Upper Columbia Aquifer
      • 7-14 Time History of Simulated Constituent Concentrations - Surficial Aquifer
      • 8-1 Conceptual Hydrogeologic Model
    • Tables (PDF)
      • 1-1 Data Collection Locations
      • 2-1 Fly Ash Data Summary
      • 2-2 Surface Water Data Summary
      • 2-3 Groundwater Data Summary
      • 2-4 Duplicate Sample Data Summary
      • 2-5 General Water Quality Parameters
      • 3-1 Water Level Data
      • 3-2 Water Quality Data Summary Statistics
      • 3-3 Water Quality Data Analysis
      • 4-1 APT Well Construction
      • 4-2 AQTESOLV Results
      • 5-1 Summary of HELP Model Simulations and Calculated Leachate Production Rates
      • 6-1 Groundwater Model Layers
      • 6-2 Assigned Model Hydraulic Properties
      • 6-3 Steady State Model Calibration Results: Aquifer Performance Test Model
      • 6-4 Steady State Model Calibration Results: High Flow Model
      • 6-5 Water Budget for Steady State Calibration: APT and High Flow Model
      • 7-1 Transport Analysis Constituents
      • 7-2 Summary of Initial Source Loading Rates and Source Decay Parameters
      • 7-3 Transport Parameters
  • Appendices (PDF)