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WATER WELL CONSTRUCTION

WATER WELL CONSTRUCTION. Statute: Part 127 – Water Supply and Sewer Systems Act 368, PA 1978, as amended (Public Health Code) (MCLA 333.12701 – 12715). R 325.1601 – 325.1781. Part 1 – Well Construction Code Part 2 - Drilling Contractors’ &

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WATER WELL CONSTRUCTION

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  1. WATER WELL CONSTRUCTION

  2. Statute: Part 127 – Water Supply and Sewer Systems Act 368, PA 1978, as amended (Public Health Code) (MCLA 333.12701 – 12715) R 325.1601 – 325.1781 • Part 1 – Well Construction Code • Part 2 - Drilling Contractors’ & • Pump Installers’ Registration • Part 3 – Drilling Machines & Service • Vehicles • Part 4 - Dewatering Wells FIRST BECAME EFFECTIVE FEB. 14, 1967 LAST REVISION – EFFECTIVE APRIL 21, 1994 For public water supply wells - Apply Part 8, Act 399, PA 1976 in addition to Part 127, Public Health Code

  3. U. S. Commerce, Bureau of Census 1990 Detailed Housing Characteristics 1.12 million household wells in Michigan HIGHEST IN NATION!

  4. PROPER WELL CONSTRUCTION MATERIALS SANITARY WELL COMPLETION PRACTICES TRAINED PROFESSIONAL WATER WELL CONTRACTORS COMPONENTS OF A SAFE & RELIABLE WATER WELL TARGET AQUIFER HAS AMPLE YIELD & SAFE WATER PROPER WATER SYSTEM MAINTENANCE SUFFICIENT SEPARATION FROM CONTAMINATION SOURCES ROUTINE MONITORING OF WATER QUALITY

  5. DEFICIENT WELL HEAD (CRACKED WELL CAP OR OPEN VENT) OLD WELLS WITH CORRODED WELL CASING SHALLOW DEPTH (OR SHORT CASING IN BEDROCK) POOR CONSTRUCTION (UNSEALED ANNULUS OR DUG WELL) WELLS MOST VUNERABLE TO MICROBIAL CONTAMINATION FLOODING, BURIED WELL HEAD OR SUBMERGED IN WELL PIT SEWER LINE BREAK, SEWAGE OVERFLOW OR CROSS- CONNECTION TOO CLOSE TO SEPTIC SYSTEM, AGRIC. RUNOFF OR ABANDONED WELL

  6. WATER WELL USE PUBLIC SUPPLY AGR. IRRIGATION INDUSTRIAL TEST WELL OTHER OTHER 2% HOUSEHOLD 98%

  7. RADIUS OF INFLUENCE STATIC WATER LEVEL WATER TABLE DRAWDOWN CONE OF DEPRESSION PUMPING WATER LEVEL AQUIFER COMMON WATER WELL TERMS

  8. Types of Water Wells • DRILLED • DRIVEN • DUG

  9. WATER WELL DESIGN • Provide well that meets needs of owner • Obtain highest yield with minimal drawdown (consistent w/ aquifer capabilities) • Provide suitable quality water (potable and turbidity-free for drinking water wells) • Provide long service life (25+ years) NEW: Minimize impacts on neighboring wells & aquatic environments

  10. DRILLED WELLS • Terminated in glacial drift (sand, gravel) or bedrock • Constructed with rotary, cable tool, jetting, hollow rod or auger drilling methods • 2 in. or larger casing (Domestic wells: 4 – 6 inch diameter)

  11. DRILLED WELLS • Casing material: Steel or PVC plastic • Installed by well drilling contractors • Much more common than driven or dug wells • Most are >50 ft. deep (avg. 125 ft.) • MOST SANITARY WELL TYPE

  12. WATER WELL DRILLING METHODS IN MICHIGAN LESS COMMON: MOST COMMON: CABLE TOOL 10% AUGER 2.5% ROTARY (Mud & Air) 84% JETTING 1% HOLLOW ROD 0.5% OTHER 2% EMERGING TECHNOLOGY DUAL TUBE ROTARY HORIZONTAL SONIC

  13. Rotary Cable Tool

  14. TABLE DRIVE ROTARY MUD HOSE MAST SWIVEL TABLE DRILL RODS MUD MIXER BENTONITE DRILLING FLUID DRILL BIT MUD PIT

  15. TOP HEAD DRIVE ROTARY TOP HEAD DRIVE UNIT DERRICK OR MAST DRILLING MUD RETURN FLOW HOSE DRILL RODS

  16. DRILLING RIG OPERATORCHECKING DRILL CUTTINGS DRILLING FLUID EXITING BOREHOLE STRAINER DRILLING MUD TANK

  17. DRILLER COMPLETING THE WATER WELL RECORD WATER WELL & PUMP RECORD DESCRIBES: WELL DEPTH CASING LENGTH GEOLOGIC MATERIALS PENETRATED STATIC WATER LEVEL PUMPING WATER LEVEL PUMPING RATE GROUTING MATERIALS WELL LOCATION PUMPING EQUIPMENT DRILLERS NAME DRILLING RIG OPERATOR

  18. TYPICAL ROTARY WELL CONSTRUCTIONSEQUENCE OVERSIZED BOREHOLE DRILLED 1 IDENTIFY AQUIFER 2 INSTALL CASING (& SCREEN) 3 YIELD TEST & WATER SAMPLING 6 WELL DEVELOPMENT 5 GROUT ANNULAR SPACE 4

  19. Bentonite Drilling Fluid - Functions - • REMOVAL OF DRILL CUTTINGS FROM BOREHOLE • STABILIZE THE BOREHOLE • COOL AND LUBRICATE DRILL BIT • CONTROL FLUID LOSS TO GEOLOGIC FORMATIONS • DROP DRILL CUTTINGS INTO MUD PIT • FACILITATE COLLECTION OF GEOLOGIC DATA • SUSPEND CUTTINGS WHEN DRILLING FLUID CIRCULATION STOPS

  20. Temporary well cap - installed between well drilling and pump hook-up

  21. Sanitary well cap (overlapping & self-draining) Screened air vent on underside of well cap Tight seal between cap and casing Electrical conduit Well casing pipe

  22. This drilled well has an older style well cap that does not seal tightly to the well casing. Insects and small animals can enter the well and contaminate the drinking water. Caps of this design are not acceptable and should be replaced.

  23. DRILLED WELL COMPONENTS WELL CAP or SEAL BOREHOLE SCREENED WELL CASING GROUT PACKER SCREEN

  24. DRILLED WELL COMPONENTS WELL CAP BEDROCK WELL BOREHOLE CASING GROUT OPEN HOLE IN BEDROCK AQUIFER NO CASING IN ROCK BOREHOLE

  25. BOREHOLE MINIMUM 2 IN. LARGER THAN CASING IF GROUTING THRU CASING MINIMUM 2 7/8 IN. LARGER THAN CASING IF GROUTING WITH GROUT PIPE OUTSIDE CASING Vertical circular boring to reach aquifer (water bearing geologic material)

  26. CASING Steel or plastic pipe installed to keep borehole wall from collapsing Houses submersible pump or turbine bowls & drop pipe STANDARD LENGTHS STEEL 21 FT. PLASTIC 20 FT. MINIMUM 25 FT. CASING LENGTH BELOW GRADE

  27. WELL CAP or SEAL Mechanical device to prevent contaminants (including insects) from entering well casing OVERLAPPING SEALED TIGHTLY TO CASING SCREENED AIR VENT TIGHT SEAL TO ELECTRICAL CONDUIT

  28. Device that seals space between casing & telescoped screen to keep sand out of well PACKER (Coupling with neoprene rubber flanges)

  29. Intake device to allow water to enter well and keep sand out Structural support of aquifer material Wire-wrapped screen most common SCREEN

  30. K - PACKER SCREEN BLANK WELL SCREEN

  31. GROUT • Impermeable cement or bentonite clay slurry placed in annular space between borehole and casing to: • prevent well contamination • maintain separation of aquifers • preserve artesianaquifers TOP VIEW CASING BOREHOLE

  32. DOWNWARD LEAKAGE AROUND UNGROUTED CASING INFILTRATION FROM SURFACE CONTAMINANTS STATIC WATER LEVEL CONTAMINANT PLUME UNSEALED ANNULAR SPACE AROUND CASING DOWNWARD LEAKAGE UNCONFINED AQUIFER

  33. UPWARD LEAKAGE AROUND UNGROUTED CASING (Artesian Condition) STATIC WATER LEVEL UNCONFINED AQUIFER CONFINING LAYER CONFINED AQUIFER UPWARD LEAKAGE

  34. BENEFITS OF WELL GROUTING • PREVENT CONTAMINANT MIGRATION FROM SURFACE (Keeps surface runoff from moving downward along well casing) • SEAL OFF POOR QUALITY AQUIFERS (Prevents mixing of water from different aquifers) • PRESERVE ARTESIAN AQUIFER PROPERTIES • ADDED SEALING OF CASING JOINTS

  35. WELL GROUTING MATERIALS TYPE COMPOSITION CHARACTERISTICS • FLEXIBLE LOWER STRENGTH SEAL • MAY SUBSIDE IN VADOSE ZONE • MOST POPULAR DUE TO LOWER COST AND TARGETED MARKETING • WASH-OUT UNDER ARTESIAN PRESSURE • NO HEAT OF HYDRATION • MORE WIDELY USED IN OIL FIELD THAN WATER WELLS • HIGHER STRENGTH RIGID SEAL • BEST CHOICE FOR BEDROCK WELLS & FLOWING WELLS • HEAT OF HYDRATION & MICROANNULUS CONCERNS • MORE PERMEABLE THAN NEAT CEMENT GROUT • MORE DIFFICULT TO PUMP (ABRASIVE) • GOOD CHOICE FOR LARGE DIAMETER WELLS BENTONITE SLURRY POWDERED BENTONITE & WATER GRANULAR BENTONITE, POLYMER & WATER NEAT CEMENT PORTLAND CEMENT & WATER CONCRETE GROUT PORTLAND CEMENT, SAND & WATER

  36. GRANULAR BENTONITE POURED INTO MIX WATER PORTABLE GROUTING MACHINE (MIXER & PUMP) GROUT PIPE TO BOTTOM OF ANNULAR SPACE BENTONITE GROUT RETURN AT SURFACE (GELATIN – OATMEAL TEXTURE)

  37. WELL GROUTING ROTARY VS. CABLE TOOL GROUT PIPE IN ANNULAR SPACE DRY GRANULAR BENTONITE POURED AROUND CASING WELL CASING IN OVERSIZED BOREHOLE GROUT FOLLOWS DRIVE SHOE AS CASING IS DRIVEN • DEPTH OF GROUT TRAVEL IS UNCERTAIN • LIMITED BY HIGH WATER TABLE GROUT PUMPED FROM BOTTOM

  38. BEDROCK WELL DETAILS CASING PIPE SHALE TRAP OR SHALE PACKER GROUT PREVENTS GROUT SPILLAGE INTO BEDROCK BOREHOLE BETTER SEAL AT BEDROCK INTERFACE TOP OF BEDROCK BEDROCK BOREHOLE (SMALLER DIAMETER THAN CASING)

  39. Groundwater Concerns in Karst Bedrock UNPLUGGED ABANDONED WELL SEWAGE SYSTEM AGRICULTURAL WASTE & RUNOFF SINKHOLE CONTAMINATED WATER SEEPS DOWNWARD THROUGH THIN SOIL LAYER INTO FRACTURES & CREVICES IN KARST BEDROCK • SIGNIFICANT RAINFALL OVER SHALLOW CARBONATE BEDROCK • CAN CAUSE: • SURGE IN WATER LEVELS (Increases hydraulic pressure) • INCREASED SURFACE WATER-TO-GROUNDWATER INTERCHANGE • FLUSHING OF TURBIDITY & ORGANIC MATTER INTO • GROUNDWATER

  40. PROPER WELL CONSTRUCTION IN KARST SURFACE GLACIAL DRIFT OVER BEDROCK CASING & GROUT EXTENDING THRU UPPER BEDROCK IF BEDROCK WITHIN 25 FT OF SURFACE: MINIMUM 25 FT OF CASING GROUTED WITH NEAT CEMENT – BENTONITE GROUT NOT PERMITTED TOP OF BEDROCK SEVERELY WEATHERED LIMESTONE BEDROCK FRACTURES & INTERCONNECTED SOLUTION CHANNELS SHALE UNCASED BOREHOLE IN BEDROCK LIMESTONE

  41. POOR WELL CONSTRUCTION IN KARST SURFACE GLACIAL DRIFT OVER BEDROCK CASING & GROUT ONLY EXTEND INTO TOP OF BEDROCK EVEN THROUGH CASING & GROUTING EXTENDS 25 FT. SAFE WATER QUALITY CANNOT BE ASSURRED TOP OF BEDROCK SEVERELY WEATHERED LIMESTONE BEDROCK FRACTURES & INTERCONNECTED SOLUTION CHANNELS BECAUSE BOREHOLE BELOW CASING INTERCEPTS SHALLOW, FRACTURED BEDROCK… WELL IS VULNERABLE TO CONTAMINATION FROM SEPTIC SYSTEMS, LUSTs, AGRICULTURAL CHEMICALS & SURFACE WATER INFILTRATION SHALE SYMPTOMS – E.COLI OR SURFACE WATER INDICATORS PRESENT AND SUSCEPTIBLE TO TURBIDITY AFTER HEAVY RAINFALL UNCASED BOREHOLE IN BEDROCK LIMESTONE

  42. WELL CASING DEPTH IN KARST GLACIAL DRIFT OVER BEDROCK SEVERELY WEATHERED LIMESTONE BEDROCK FRACTURES & INTERCONNECTED SOLUTION CHANNELS • BENEFITS OF EXTENDING WELL CASING THROUGH UPPER FRACTURED BEDROCK: • TRAVEL TIME OF AQUIFER RECHARGE WATER IS INCREASED • DIE-OFF OF PATHOGENS MORE LIKELY TO OCCUR • IMPROVES CHANCES OF COLIFORM-FREE WATER UNCASED BOREHOLE IN BEDROCK LIMESTONE

  43. CASING MATERIALS COMPARISON PVC PLASTIC STEEL VS. Non-corroding Corrodes Lower strength Higher strength Fewer water quality Rusty water Rotary construction only Suitable for any drilling method 1/3 cost of steelNo heat of hydration impact from cement grout SDR 17 needed past 200 ft. complaints

  44. TYPICAL 5 IN. DIAMETER HOUSEHOLD WELL CONTRACTOR IS CUTTING PVC CASING TO FINISHED HEIGHT (MIN. 12 IN. ABOVE GROUND)

  45. DOUBLING WELL DIAMETER 10% YIELD INCREASE DOUBLING SCREEN LENGTH DOUBLES WELL YIELD WELL DIAMETER: Doubling well diameter appreciably increases well yield MYTH FACT

  46. SCREENED WELLS Naturally Developed Filter Packed (a/k/a Gravel-Packed) WELL SCREEN SET IN NATIVE GEOLOGIC MATERIALS (SAND OR GRAVEL) GRADED-WASHED SAND PLACED OUTSIDE WELL SCREEN

  47. FILTER - PACK BENEFITS • Greater porosity • Higher hydraulic conductivity • Reduced drawdown • Higher yield • Reduced entrance velocity • Faster development • Easier grouting • Longer well life • Improved well rehabilitation • Reduce sand pumping

  48. FILTER-PACKED WELL CONSTRUCTION CASING FILTER-PACK SANDPLACED BETWEEN BOREHOLE & SCREEN BEFORE GROUTING GROUT CASING CENTERING GUIDES (OPTIONAL) FILTER PACK IS NOT ALLOWED TO EXTEND MORE THAN 10 FEET ABOVE TOP OF SCREEN SCREEN

  49. DISINFECTED FILTER SAND POURED INTO ANNULUS AFTER CASING & SCREEN ARE INSTALLED AND DRILLING MUD IS FLUSHED FROM BOREHOLE

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