COPYRIGHTED MATERIAL. Contents PART ONE: THEORY...1. Preface to the Third Edition xiii. About the Authors xv. Acknowledgements xvii

Transcription

1 Preface to the Third Edition xiii About the Authors xv Acknowledgements xvii Contents PART ONE: THEORY Groundwater in Construction Groundwater in the Hydrologic Cycle Origins of Dewatering Development of Modern Dewatering Technology 6 2. The Geology of Soils Geologic Time Frame Formation of Soils Mineral Composition of Soils Rivers Lakes Estuaries Beaches Wind Deposits Glaciers The Pleistocene Epoch Rock Limestone and Coral Tectonic Movements Man-made Ground Soils and Water Soil Structure 22 COPYRIGHTED MATERIAL v

2 vi CONTENTS 3.2 Gradation of Soils Porosity, Void Ratio, and Water Content Relative Density, Specific Gravity, and Unit Weight Capillarity and Unsaturated Flow Specific Yield and Specific Retention Hydraulic Conductivity Plasticity and Cohesion of Silts and Clays Unified Soil Classification System (ASTM D-2487) Soil Descriptions Visual and Manual Classification of Soils Seepage Forces and Soil Stress Gravity Drainage of Granular Soils Drainage of Fine-grained Soils: Pore Pressure Control Settlement as a Result of Dewatering Preconsolidation Other Side Effects of Dewatering Hydrology of the Ideal Aquifer Definition of the Ideal Aquifer Transmissivity T Storage Coefficient C s and Specific Yield Pumping from a Confined Aquifer Recovery Calculations The Unconfined or Water Table Aquifer Specific Capacity Characteristics of Natural Aquifers Anisotropy: Stratified Soils Horizontal Variability Recharge Boundaries: Radius of Influence R Barrier Boundaries Delayed Release from Storage Dewatering Design Using Analytical Methods Radial Flow to a Well in a Confined Aquifer Radial Flow to a Well in a Water Table Aquifer Radial Flow to a Well in a Mixed Aquifer Flow to a Drainage Trench from a Line Source The System as a Well: Equivalent Radius r s Radius of Influence R Hydraulic Conductivity K and Transmissivity T Initial Head H and Final Head h Partial Penetration Storage Depletion Specific Capacity of the Aquifer Cumulative Drawdown or Superposition Capacity of the Well Q w Flow Net Analysis and the Method of Fragments 79

3 CONTENTS vii 6.15 Concentric Dewatering Systems Vertical Flow Gravel Tremie Groundwater Modeling Using Numerical Methods Models in Dewatering Practice When to Consider a Numerical Model Principal Steps in Model Design and Application The Conceptual Model: Defining the Problem to Be Modeled Selecting the Program Introduction to MODFLOW Verification Calibration Prediction and Parametric Analyses Some Practical Modeling Problems D Model: Well System in a Water Table Aquifer Calibrating the Model D Model: Partial Penetration D Model: Vertical Flow D Model: Transient Analysis of a Progressive Trench Excavation Piezometers for Groundwater Measurement and Monitoring Subsurface Conditions Ordinary Piezometers and True Piezometers Piezometer Construction Verification of Piezometer Performance Obtaining Data from Piezometers Pore Pressure Piezometers in Fine-grained Soils Direct Push Technologies for Piezometer Installation Pumping Tests When a Pumping Test Is Advisable Planning the Pumping Test Design of the Pumping Well Piezometer Array Duration of Drawdown and Recovery Pumping Rate Monitoring the Pumping Test Analysis of Pumping Test Data Tidal Corrections Well Loss Step Drawdown Tests Testing of Low-yield Wells Delayed Storage Release: Boulton Analysis Surface Hydrology Lakes and Reservoirs Bays and Ocean Beaches 141

4 viii CONTENTS 10.3 Rivers Precipitation Disposal of Dewatering Discharge Water from Existing Structures Geotechnical Investigation for Dewatering Investigation Approach and Objectives Preliminary Studies and Investigations Borings In Situ Test Methods Piezometers and Observation Wells Borehole Seepage Tests for Evaluation of Hydraulic Conductivity Laboratory Analysis of Samples Chemical Testing of Groundwater Geophysical Methods Pumping Tests Permanent Effect of Structures on the Groundwater Body Investigation of the Potential Side Effects of Dewatering Presentation in the Bidding Documents Pump Theory Types of Pumps Used in Dewatering Total Dynamic Head Pump Performance Curves Vacuum Pumps Air Lift Pumping Testing of Pumps Groundwater Chemistry, Bacteriology, and Fouling of Dewatering Systems Types of Corrosion Corrosive Groundwater Conditions Dewatering in Corrosive Groundwater Conditions Incrustation Mineral Incrustation Biological Incrustation Dewatering Systems and Incrustation Field Evaluation of Well Fouling Rehabilitation and Maintenance Analysis of Groundwater Contaminated Groundwater Contaminants Frequently Encountered Design Options at a Contaminated Site Estimating Water Quantity to Be Treated Other Considerations in Treatment Design Elements of Groundwater Treatment Recovery of Contaminated Water with Dewatering Techniques Dynamic Barriers Wellpoint Systems and Multiphase Contaminants 232

5 CONTENTS ix 14.9 Reinjection Health and Safety Regulating Authorities Piping Systems Dewatering Pipe and Fittings Losses in Discharge Piping Losses in Wellpoint Header Lines Losses in Ejector Headers Water Hammer 243 PART TWO: PRACTICE Choosing a Method of Groundwater Control To Pump or Not to Pump Open Pumping Versus Predrainage Methods of Predrainage Methods of Cutoff and Exclusion Methods in Combination Sumps, Drains, and Open Pumping Soil and Water Conditions Boils and Blows Construction of Sumps Ditches and Drains Gravel Bedding Slope Stabilization with Sandbags, Gravel, and Geotextiles Use of Geotextiles Soldier Piles and Lagging: Standup Time Longterm Effect of Buried Drains Leaking Utilities Battered Wellpoints Horizontal Wellpoints Deep Well Systems Testing During Well Construction Well Installation and Construction Methods Wellscreen and Casing Filter Packs Development of Wells Well Construction Details Pressure Relief Wells, Vacuum Wells Wells That Pump Sand Systems of Low-capacity Wells Wellpoint Systems Suction Lifts Single and Multistage Systems 310

6 x CONTENTS 19.3 Wellpoint Design Wellpoint Spacing Wellpoint Depth Installation of Wellpoints Filter Sands Wellpoint Pumps, Header, and Discharge Piping Tuning Wellpoint Systems Air/ Water Separation Automatic Mops Vertical Wellpoint Pumps Wellpoints for Stabilization of Fine-grained Soils Wellpoint Systems for Trench Work Ejector Systems and Other Methods Two-pipe and Single-pipe Ejectors Ejector Pumping Stations Ejector Efficiency Design of Nozzles and Venturis Ejector Risers and Swings Ejector Headers Ejector Installation Ejectors and Groundwater Quality Ejectors and Soil Stabilization Drilled Horizontal Wells Trencher Drains Groundwater Cutoff Structures Cutoff Terminology and Efficiency Steel Sheet Piling Slurry Trenches Slurry Diaphragm Walls Secant Piles Deep Soil Mixing Tremie Seals Grouting Methods Permeation Grouting Jet Grouting Rock Curtain Grouting Grouting of Structures and Flowpaths Dewatering and Groundwater Control for Soft Ground Tunneling Soft Ground Tunneling Methods with Conventional Dewatering Ground Behavior Mixed-face Ground Conditions Dewatering Design for Tunnels Methods of Tunnel Predrainage Tunneling Techniques with Built-in Groundwater Control 500

7 CONTENTS xi 23.7 Compressed Air Tunneling Dewatering of Access Shafts, Penetrations, and Starter Tunnels Ground Freezing General Principles Freezing Applications Freezing Methods and Equipment Ground Freezing and Soils Design Effect of Groundwater Movement Ground Movement Potential as a Result of Artificial Freezing Artificial Recharge Recharge Applications Design Objectives Potential Problems with Recharge Water and Plugging of Wells Sources of Recharge Water Treatment of Recharge Water Construction of Recharge Systems Operation and Maintenance of Recharge Systems Permits for Recharge Operations Electrical Design for Dewatering Systems Electrical Motors Motor Controls Power Factor Electric Generators Switchgear and Distribution Systems Grounding of Electrical Circuits Cost of Electrical Energy Long-term Dewatering Systems Types of Long-term Systems Access for Maintenance Instrumentation and Controls Dewatering Costs Format of the Estimate Basic Cost Data Mobilization Installation and Removal Operation and Maintenance Summary Specialty Dewatering Subcontractor Quotations Dewatering Specifications, Allocation of Risk, Dispute Avoidance, and Resolution of Disputes Performance Specifications 585

8 xii CONTENTS 29.2 Owner-designed Dewatering Systems Specified Minimum Systems Dewatering Submittals Third-party Damage Caused by Dewatering Differing Site Conditions Disputes Review Board 595 Appendix A 597 Appendix B 603 Appendix C 620 Index 623