NR 141.05(6)(d)(d) “Bentonite chips” means commercially processed angular fragments of pure bentonite, without additives. NR 141.05(7)(7) “Bentonite — cement grout” means a mixture with the ratio of 5 pounds of bentonite with 94 pounds of Portland cement and 8.5 gallons of water from a known safe and uncontaminated source. NR 141.05(8)(8) “Bentonite — fine sand slurry” means a mixture with the minimum ratio of 50 pounds of bentonite with 100 gallons of water from a known safe and uncontaminated source and 10-25% sand by volume for a mud weight of 11 pounds per gallon. NR 141.05(9)(9) “Borehole” means a circular hole deeper than it is wide, constructed in earth material for the purpose of either installing a well or obtaining geologic or groundwater related data. Boreholes are also referred to as drillholes. NR 141.05(10)(10) “Clay” means an inorganic soil with low permeability characteristics and a plasticity index of 7 or more. NR 141.05(11)(11) “Coarse sand” means a well sorted sand with a predominant grain size between 4.76mm and 2.0mm as established by the unified soil classification system. NR 141.05(12)(12) “Concrete” means a slurry mixture with a ratio of 94 pounds of cement, equal volumes of dry sand and gravel and 5 to 6 gallons of water from a known safe and uncontaminated source. The ratio of sand and gravel to cement may not exceed 3 parts to one. NR 141.05(13)(13) “Department” means the department of natural resources. NR 141.05(14)(14) “Driven point well” means a well constructed by joining a drive point with lengths of pipe and driving the assembly into the ground with percussion equipment or by hand, without first removing material below the 10 foot depth. NR 141.05(15)(15) “Filter pack” means the sand, gravel or both placed in direct contact with the well screen. NR 141.05(16)(16) “Filter pack seal” means the sealing material placed in the annular space above the filter pack and below the annular space seal to prevent the migration of annular space sealant into the filter pack. NR 141.05(17)(17) “Fine sand” means a well sorted sand with a predominant grain size between .42mm and .074mm, as established by the unified soil classification system. NR 141.05(18)(18) “Granular bentonite slurry” means a thoroughly blended mixture of up to 30 pounds of untreated bentonite powder added to 100 gallons of water from a known safe and uncontaminated source with a minimum of 100 pounds of untreated bentonite granules mixed together by a Venturi-hopper mud mixer or other equivalent high shear mixer. NR 141.05(19)(19) “Gravel” means an unconsolidated material with the predominant grain size being between 76.2mm and 4.76mm, as established by the unified soil classification system. NR 141.05(20)(20) “Groundwater” means any waters of the state, as defined in s. 281.01 (18), Stats., occurring in a saturated geologic formation of rock or unconsolidated material. NR 141.05(21)(21) “Groundwater monitoring well” means any cased excavation or opening into the ground made by digging, boring, drilling, driving, jetting or other methods for the purpose of determining the physical, chemical, biological or radiological properties of groundwater. Groundwater monitoring wells may be piezometers, water table observation wells or both. NR 141.05(21m)(21m) “High-solids grout” means a thoroughly blended mixture of water from a known safe and uncontaminated source with untreated bentonite, without additives, which has been approved by the department. NR 141.05(22)(22) “Hollow stem auger drilling” means a drilling method where continuous flighting is welded to a hollow stem pipe. The flighting carries drill cuttings to the surface as the flighting is rotated and pushed down into the earth. NR 141.05(23)(23) “Inside diameter” means the horizontal distance between the inner walls of a well casing, hollow stem auger or tremie pipe. NR 141.05(24)(24) “Medium sand” means a well sorted sand with a predominant grain size between 2.0mm and .42mm, as established by the unified soil classification system. NR 141.05(25)(25) “Montmorillonite” means a group of expanding lattice clay minerals of the general formula: R.33Al2Si4010(OH)2 ∘ H2O, where R means one or more cations of sodium, potassium, magnesium or calcium and where Al means aluminum, Si means silicon, O means oxygen and H means hydrogen. NR 141.05(26)(26) “Mud rotary drilling” means a drilling method whereby a borehole is advanced by using a circular rotating action applied to a string of drilling rods which have a diffused discharge bit attached to the bottom of the string. A bentonite and water mud slurry is used to provide borehole stability, to cool the bit and to carry cuttings to the ground surface. NR 141.05(27)(27) “Neat cement grout” means a slurry mixture with a ration of 94 pounds of Portland cement mixed with 5 to 6 gallons of water from a known safe and uncontaminated source. NR 141.05(28)(28) “Percussion drilling” means a drilling method using a cable tool drilling machine or a drilling method whereby the permanent or temporary well casing is driven, or is set into a borehole and then driven. NR 141.05(29)(29) “Permanent groundwater monitoring well” means any groundwater monitoring well in place for 60 days or longer. NR 141.05(30)(30) “Piezometer” means a groundwater monitoring well, sealed below the water table, installed for the specific purpose of determining either the elevation of the potentiometric surface or the physical, chemical, biological or radiological properties of groundwater at some point within the saturated zone or both. NR 141.05(31)(31) “Potentiometric surface” or “piezometric surface” means an imaginary surface representing the total head of groundwater and is the level to which water will rise in a well. NR 141.05(33)(33) “Purge” means an action that removes water from the well, commonly accomplished by using a pump or bailer.