Chapter NR 141

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(32) (32) “Psi” means pounds per square inch.

NR 141.05(33) (33) “Purge” means an action that removes water from the well, commonly accomplished by using a pump or bailer.

NR 141.05(33m) (33m) “Recovery well” means a well intended and designed to capture and remove contaminated groundwater or non-aqueous phase liquids from the subsurface.

NR 141.05(34) (34) “Rotary wash drilling” means a drilling method whereby metal temporary casing is advanced into the borehole by driving. At selected intervals, the temporary casing is cleaned out using rotary drilling tools by pumping clean water through the rod to flush out accumulated cuttings. This drilling method is also known as wash bore or wash down drilling.

NR 141.05(35) (35) “Sand-cement grout” means a mixture of cement, sand and water in the proportion of 94 pounds of Portland cement, one cubic foot of dry sand and 5 to 6 gallons of water from a known safe and uncontaminated source.

NR 141.05(36) (36) “Sediment” means any solid material dropping from suspension in water, including clay, silt, sand and gravel sized particles.

NR 141.05(37) (37) “Solid stem auger drilling” means a drilling method where continuous flighting is welded onto a solid stem pipe. The flighting carries drill cuttings to the surface as the flighting is rotated and pushed down into the earth. The borehole is created by a cutting bit located at the tip of the lead auger.

NR 141.05(38) (38) “Specific gravity” means the weight of a particular volume of substance compared to the weight of an equal volume of water at a reference temperature.

NR 141.05(39) (39) “Surge” means an action causing water to move rapidly in and out of the well screen, thereby removing fine material from the surrounding aquifer.

NR 141.05(40) (40) “Temporary groundwater monitoring well” means any groundwater monitoring well in place for less than 60 days.

NR 141.05(41) (41) “Top of bedrock” or “top of firm rock” means at least 70% of the drill cuttings being either:

NR 141.05(41)(a) (a) Angular rock fragments, as in the case of crystalline rock; or

NR 141.05(41)(b) (b) Rock fragments composed of individual grains or rock particles that are cemented together to form an aggregate as opposed to a single sediment particle.

NR 141.05(42) (42) “Tremie pipe” means a pipe or hose used to install well construction materials in an annular space or a borehole.

NR 141.05(43) (43) “Unconsolidated material” means that material found above firm bedrock, composed of single sediment particles, individual grains or rock fragments. Unconsolidated material includes but is not limited to clay, silt, sand, gravel, loess, peat and organic soil.

NR 141.05(44) (44) “Unified soil classification system” means the soil designation system based on the physical properties of the soil developed from the airfield classification system in 1952 and adopted by the American society for testing and materials in standard test method D2487-83.

NR 141.05 Note Note: A copy of this publication is available for inspection at the offices of the department of natural resources, the secretary of state, and the legislative reference bureau and may be obtained for personal use from the American Society for Testing and Materials, 1916 Race Street, Philadelphia, Pennsylvania 19103.

NR 141.05(45) (45) “Water table” means the surface of unconfined groundwater where the water pressure is equal to atmospheric pressure.

NR 141.05(46) (46) “Water table observation well” means any groundwater monitoring well, in which the screen or open borehole intersects a water table, which is installed for the specific purpose of determining either the elevation of the water table or the physical, chemical, biological or radiological properties of groundwater at the water table or both.

NR 141.05 Note Note: Construction of a typical water table observation well is depicted in Figure 1.

NR 141.05(47) (47) “Well” means any borehole or other excavation or opening in the ground deeper than it is wide constructed for the purpose of obtaining or monitoring groundwater.

NR 141.05(48) (48) “Well depth” means the distance from the ground surface to the bottom of the well screen or to the bottom of the open hole when a well screen is not used.

NR 141.05(49) (49) “Well volume” means the volume of water contained in the well casing and the filter pack.

NR 141.05 History History: Cr. Register, January, 1990, No. 409, eff. 2-1-90; am. (7), (8) and (18), cr. (2m), (21m) and (33m), Register, June, 1991, No. 426, eff. 7-1-91; correction in (20) made under s. 13.93 (2m) (b) 7., Stats., Register, March, 2000, No. 531.

NR 141.055 NR 141.055 Borehole protection. If a borehole is left open, protective measures shall be taken to prevent the borehole from acting as a conduit for contamination or becoming a safety hazard.

NR 141.055 History History: Cr. Register, January, 1990, No. 409, eff. 2-1-90.

NR 141.06 NR 141.06 Soil testing. Specific soil sampling and testing procedures are specified in other chapters related to wastewater and solid and hazardous waste disposal facilities.

NR 141.06 Note Note: See chs. NR 110, 206, 214, 508, 512, and 660 to 679.

NR 141.06 History History: Cr. Register, January, 1990, No. 409, eff. 2-1-90.

NR 141.065 NR 141.065 Well location.

NR 141.065(1) (1) Monitoring wells installed where prior department approval is required shall be installed at the locations indicated on plans and specifications approved by the department prior to installation.

NR 141.065(2) (2) Following installation of the wells, an as-built plan map shall be submitted specifying the exact vertical and horizontal location of the wells. All monitoring well locations shall be reported to the department on a plan map drawn to a specific scale. The map shall indicate structure boundaries, property boundaries, any nearby surface waters and a north arrow. The plan shall show the wells in relation to each other, to property and structure boundaries, and to a common reference point on a horizontal grid system. The origin of the grid system shall be located according to latitude and longitude or according to the state plane coordinate system. The exact vertical location of the top of the well casing shall be referenced to the nearest benchmark for the national geodetic survey datum to an accuracy of 0.01 feet. This plan map shall show the exact location of the installed well on a horizontal grid system which is accurate to within one foot. Direction of groundwater flow shall be indicated. In addition, an 8.5-inch by 11-inch site map drawn to scale according to the horizontal grid system shall be submitted showing the location of wells and structures on the site.

NR 141.065(3) (3) The well casings for wells constructed in a floodplain or floodway shall terminate a minimum of 2 feet above the regional flood elevation for the well site.

NR 141.065 History History: Cr. Register, January, 1990, No. 409, eff. 2-1-90; am. (2), Register, June, 1991, No. 426, eff. 7-1-91.

NR 141.07 NR 141.07 Well casing.

NR 141.07(1) (1) Specifications. All permanent groundwater monitoring wells shall be constructed of new polyvinyl chloride (PVC) well casing materials except in situations where the rock, soil or groundwater may react with PVC, in which case an approval under s. NR 141.31 for alternative materials shall be requested. All PVC casing materials shall meet national sanitation foundation standard 14 and ASTM D1785 specifications for any one of the following cell classifications: 12454-B, 12454-C, 11443-B, 14333-D, 13233 or 15223-B. All casing shall have a minimum inside diameter of 1.9 inches. In unconsolidated geologic formations, all wells less than or equal to 100 feet in depth shall be constructed of at least schedule 40 PVC casing and all wells greater than 100 feet in depth shall be constructed of at least schedule 80 PVC casing. Groundwater monitoring wells shall be installed with well casing no larger than a 4-inch inside diameter. Groundwater monitoring wells shall have a vented cap except as provided in s. NR 141.13 (4) (b).

NR 141.07(2) (2) Reference. The listed national sanitation foundation and ASTM references are available for inspection at the offices of the department of natural resources, the secretary of state, and the legislative reference bureau and may be obtained for personal use from the National Sanitation Foundation, 3475 Plymouth Road, P.O. Box 1468, Ann Arbor, Michigan 48106, and the American Society for Testing and Materials, 1916 Race Street, Philadelphia, Pennsylvania 19103.

NR 141.07(3) (3) Assembly and installation. All casing couplings shall be constructed of flush threaded joints. Solvent welded joints may not be used without prior written approval by the department. The casing shall be centered in the borehole.

NR 141.07(4) (4) Inspection. Prior to use, the casings and couplings shall be inspected for cuts, deformations, gouges, deep scratches, damaged ends and other imperfections. Any casing or coupling having such a defect may not be used.

NR 141.07 History History: Cr. Register, January, 1990, No. 409, eff. 2-1-90; am. (1), Register, June, 1991, No. 426, eff. 7-1-91; correction in (2) made under s. 13.92 (4) (b) 6., Stats., Register March 2011 No. 663.

NR 141.09 NR 141.09 Well screen.

NR 141.09(1) (1) Specifications. All permanent groundwater monitoring well screens shall be constructed of material which is nonreactive with the constituents in soils and groundwater at the monitoring location. The well screen may not be hand cut and may not be wrapped with filter cloth. The well screen slot size shall be sized to retain at least 90% of the grain size of the collapsed formation, based on a sieve analysis, when collapsed formation is used as filter pack material or at least 90% of the grain size of the filter pack, based on a sieve analysis, if material other than collapsed formation is used. Well screens on water table observation wells may not exceed 15 feet in length. Well screens on piezometers installed for the purpose of determining the elevation of the potentiometric surface may not exceed 5 feet in length.

NR 141.09 Note Note: Well screens for wells other than the water table observation wells and piezometers identified above may vary in length.

NR 141.09(2) (2) Assembly and installation. All well screens shall be permanently joined to the well casing by flush threaded joints. All joints shall be watertight. All well screens shall be centered in the borehole. Monitoring wells installed in bedrock using an open borehole may be constructed without a well screen.

Figure 1.
Typical water table observation well and piezometer construction details.

NR 141.09 History History: Cr. Register, January, 1990, No. 409, eff. 2-1-90; am. (1), Register, June, 1991, No. 426, eff. 7-1-91.

NR 141.10 NR 141.10 Tremie pipes and sealing procedures.

NR 141.10(1) (1) Materials. The tremie pipe used for the placement of sealant materials shall be one of the following materials:

NR 141.10(1)(a) (a) Metal pipe,

NR 141.10(1)(b) (b) Rubber-covered hose reinforced with braided fiber or steel and rated for at least 300 psi, or

NR 141.10(1)(c) (c) Thermoplastic pipe rated for at least 100 psi including:

NR 141.10(1)(c)1. 1. Polyvinyl chloride (PVC)

NR 141.10(1)(c)2. 2. Chlorinated polyvinyl chloride (CPVC),

NR 141.10(1)(c)3. 3. Polyethylene (PE),

NR 141.10(1)(c)4. 4. Polybutylene (PB), and

NR 141.10(1)(c)5. 5. Acrylonitrite butadiene styrene (ABS).

NR 141.10(2) (2) Procedures. This subsection describes department approved sealant placement methods when a tremie pipe is used.

NR 141.10(2)(a) (a) The estimated and actual volume of sealing material used shall be calculated and reported to the department.

NR 141.10(2)(b) (b) The sealant material shall be placed in one continuous operation in such a manner as to not disturb the integrity of the filter pack and seal.

NR 141.10(2)(c) (c) When a tremie pipe is used, the bottom end shall be kept submerged in the sealant material throughout the sealing process.

NR 141.10(2)(d) (d) The sealant material shall be brought up to the ground surface seal. The density of the sealant material in the annular space or borehole at the bottom of the ground surface seal shall be the same as the density of the sealant material being placed. Any settling of the sealant material shall be topped off.

NR 141.10(2)(e) (e) Tremie pipe — gravity. As depicted in Figure 2, sealing material may flow by gravity through a funnel or hopper connected to a tremie pipe. The tremie pipe shall be lowered to the bottom of the annular space or borehole to be sealed and the sealing material placed from the bottom up. The end of the tremie pipe shall be kept submerged in the grout or slurry at all times.

NR 141.10(2)(f) (f) Tremie pipe — pumped. As depicted in Figure 3, the sealing material shall be placed by a pump through a tremie pipe into the annular space or borehole. Tremie pipes used for the placing of pumped slurry or grout shall be fitted with a J-hook end or a closed end with side discharge ports.

NR 141.10 Note Note: The J-hook end or closed end with side discharge ports of the tremie pipe will direct the flow of the materials to the side or upward

Figure 2.
Conductor (tremie) pipe — gravity method

Figure 3.
Conductor (tremie) pipe — pumped method

NR 141.10 History History: Cr. Register, January, 1990, No. 409, eff. 2-1-90; am. (2) (d) and (f), Register, June, 1991, No. 426, eff. 7-1-91.

NR 141.11 NR 141.11 Filter packs. All permanent groundwater monitoring wells installed in unconsolidated material and used for the collection of water quality samples shall be constructed with filter packs. Permanent groundwater monitoring wells installed in bedrock may be constructed with filter packs. When used, the filter pack shall be the only material in contact with the well screen. The estimated and actual volume of filter pack material used shall be calculated and reported to the department. All commercially prepared filter packs installed in permanent groundwater monitoring wells shall meet the requirements in sub. (1). All other filter packs shall meet the requirements in sub. (3).

NR 141.11(1) (1) Specifications. The filter pack shall be a well sorted, silica based sand or gravel. The sand or gravel used for filter packs shall be hard and durable and shall have an average specific gravity of not less than 2.50. The sand and gravel shall be visibly free of clay, dust and micaceous and organic matter. Not more than 5% of the sand or gravel shall be soluble in a 10% hydrochloric acid solution. Thin, flat or elongated pieces of gravel, the maximum dimension of which exceeds 3 times the minimum dimension, may not constitute more than 2% of the material by weight. The filter pack for wells installed in unconsolidated material shall be sized to retain at least 50% of the surrounding formation based on a sieve analysis. In formations which are predominantly silt and clay, the filter pack shall be a fine sand. In bedrock, the filter pack shall be a medium or coarse sand or gravel. Crushed limestone, dolomite or any material containing clay or any other material that will adversely impact on the performance of the monitoring well may not be used as filter pack.

NR 141.11(2) (2) Installation. The filter pack shall extend from 6 inches beneath the bottom of the well to 2 feet above the top of the well screen. For water table observation wells constructed in areas where the depth to water table is less than 7 feet, the required filter pack height above the top of the well screen may be reduced to 6 inches to allow for the required amount of annular space sealant to be placed. To ensure that the filter pack is installed evenly surrounding the well screen and casing over the proper depth interval, a tape measure, measuring rod or similar device shall be used to measure the height of the filter pack. The tape measure, measuring rod or similar device shall be carefully raised and lowered while the filter pack is being installed to identify bridging. If bridging occurs the filter pack material shall be tamped into place, surrounding the well screen and casing, using a measuring rod or similar device.

NR 141.11(3) (3) Collapsed formation. Collapsed formation may be used as filter pack material if the collapsed formation will limit the passage of formation fines into the well screen and either an artificial filter pack cannot be installed or the formation grain size is greater than or equal to fine sand sized grains. The grain size distribution of the collapsed formation shall be such that at least 90% of the formation will be retained by the well screen based on a sieve analysis. Analysis of the collapsed formation for specific gravity and particle size shall be performed and documentation shall be submitted to the department to support its use as an acceptable filter pack. Following review of the submitted information, the department may require new well construction if the collapsed formation analysis is not consistent with the filter pack specifications.

NR 141.11 History History: Cr. Register, January, 1990, No. 409, eff. 2-1-90; am. (1) to (3), Register, June, 1991, No. 426, eff. 7-1-91.

NR 141.13 NR 141.13 Sealing requirements. All materials and procedures used in the installation of seals for permanent groundwater monitoring wells shall meet the requirements of this section. The calculated and actual volume of sealant material used for the filter pack seal and annular space seal shall be reported to the department.

NR 141.13(1) (1) Filter pack seal.

NR 141.13(1)(a) (a) Specifications. All permanent groundwater monitoring wells installed with filter packs shall be constructed with a filter pack seal. For all water table observation wells and piezometers, the filter pack seal shall extend 2 feet upward from the top of the filter pack and shall consist of 2 feet of clean fine sand. When high-solids grout, granular bentonite slurry, bentonite-cement grout or neat cement grout is used as the annular space sealant, 5 feet of bentonite shall be placed on top of the clean fine sand seal. Bentonite chips no greater than 3/8 inch in diameter or bentonite pellets shall be used for seals placed below the water table. Bentonite granules may be used for seals when there is no standing water above the filter pack and the borehole is less than 25 feet or in areas where the depth to water table is less than 7 feet. For water table observation wells constructed in areas where the depth to water table is less than 16 feet, the filter pack seal shall be reduced to 2 feet of bentonite to allow for the required amount of annular space sealant to be placed. For water table observation wells constructed in areas where the depth to water table is less than 7 feet, the required filter pack seal may be reduced to allow for the required amount of annular space sealant to be placed.

NR 141.13(1)(b) (b) Installation. A tape measure, measuring rod or similar device shall be used to ensure that the filter pack seal is installed over the proper depth interval. The tape measure, measuring rod or similar device shall be carefully raised and lowered while the filter pack seal material is being placed to identify bridging. If bridging occurs the filter pack seal material shall be tamped into place, surrounding the well casing, using a measuring rod or similar device. When a tremie pipe is used to place the filter pack seal the procedures of s. NR 141.10 (2) shall be followed. Bentonite pellets, bentonite chips or bentonite granules shall be hydrated in 2 foot lifts as placed in the borehole when placed above the water table.