Chapter NR 141
GROUNDWATER MONITORING WELL REQUIREMENTS
Tremie pipes and sealing procedures.
Drilling methods and fluids.
Disposal and decontamination.
Aquifer test or recovery wells.
Well and borehole construction documentation.
Driven point wells.
Temporary groundwater monitoring wells.
Special circumstances and exceptions.
NR 141.01 Purpose.
The purpose of this chapter is to establish minimum acceptable standards for the design, installation, construction, abandonment and documentation of groundwater monitoring wells. These rules are adopted under chs. 281
NR 141.01 History
Cr. Register, January, 1990, No. 409
, eff. 2-1-90; correction made under s. 13.93 (2m) (b) 7., Stats., Register, March, 2000, No. 531
NR 141.03 Applicability.
This chapter applies to all persons installing and abandoning groundwater monitoring wells and boreholes for purposes regulated by the department under ch. 160
, Stats., or in permits, plan approvals, licenses or orders issued under those chapters. In addition, this chapter applies to all persons installing groundwater monitoring wells and boreholes in fulfillment of terms of a contract with the department. All wells and boreholes installed for purposes regulated by the department under this chapter shall be abandoned according to s. NR 141.25
. All other wells and boreholes shall be abandoned according to the provisions of ch. NR 812
NR 141.03 Note
Additional requirements concerning soil testing and groundwater sampling are located in other chapters regulating wastewater and solid and hazardous waste disposal, see chs. NR 110
and the 600 and 700 series.
NR 141.03 History
Cr. Register, January, 1990, No. 409
, eff. 2-1-90; am. Register, June, 1991, No. 426
, eff. 7-1-91; correction made under s. 13.93 (2m) (b) 7., Stats., Register, September, 1995, No. 477
; corrections made under s. 13.93 (2m) (b) 7., Stats., Register, March, 2000, No. 531
NR 141.05 Definitions.
In this chapter:
“Air rotary drilling" means a drilling method whereby the borehole is advanced using a circular rotating action applied to a string of drilling rods which have a diffused discharge bit attached to the bottom of the rods. Pressurized air is forced through the drilling rods and cools the drilling tools and removes the cuttings from the borehole.
For wells constructed with filter packs, it is the material placed above the top of the filter pack or the filter pack seal up to the surface seal and between the well casing and the adjacent formation; or
For wells constructed into bedrock formations and without well screens, it is the material placed from the bottom of the enlarged borehole up to the surface seal, between the well casing and the adjacent formation.
“Aquifer test well" means a well installed to provide information on the hydraulic conductivity, transmissivity, storage coefficient, capture zone, specific capacity, radius of influence or other physical parameters of an aquifer, defined geologic unit, or water bearing formation through the imposition of a sustained stress on the aquifer by removal of water.
“ASTM" means american society for testing and materials.
“Bedrock" means the solid rock underlying any loose surficial material such as soil, alluvium or glacial drift. Bedrock includes but is not limited to limestone, dolomite, sandstone, shale and igneous and metamorphic rock.
“Bentonite" means a clay consisting of at least 85% sodium montmorillonite. Bentonite is available in the following forms:
“Bentonite powder" means 200 mesh pure bentonite, without additives.
“Bentonite granules" means 8 mesh pure bentonite, without additives.
“Bentonite pellets" means commercially manufactured tablets made by compressing pure bentonite, without additives, into forms greater than 1
“Bentonite chips" means commercially processed angular fragments of pure bentonite, without additives.
“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.
“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.
“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.
“Clay" means an inorganic soil with low permeability characteristics and a plasticity index of 7 or more.
“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.
“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.
“Department" means the department of natural resources.
“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.
“Filter pack" means the sand, gravel or both placed in direct contact with the well screen.
“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.
“Fine sand" means a well sorted sand with a predominant grain size between .42mm and .074mm, as established by the unified soil classification system.
“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.
“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.
“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.
“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.
“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.
“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.
“Inside diameter" means the horizontal distance between the inner walls of a well casing, hollow stem auger or tremie pipe.
“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.
“Montmorillonite" means a group of expanding lattice clay minerals of the general formula: R.33
O, 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.
“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.
“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.
“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.
“Permanent groundwater monitoring well" means any groundwater monitoring well in place for 60 days or longer.
“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.
“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.
“Purge" means an action that removes water from the well, commonly accomplished by using a pump or bailer.
“Recovery well" means a well intended and designed to capture and remove contaminated groundwater or non-aqueous phase liquids from the subsurface.
“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.
“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.
“Sediment" means any solid material dropping from suspension in water, including clay, silt, sand and gravel sized particles.
“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.
“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.
“Surge" means an action causing water to move rapidly in and out of the well screen, thereby removing fine material from the surrounding aquifer.
“Temporary groundwater monitoring well" means any groundwater monitoring well in place for less than 60 days.
“Top of bedrock" or “top of firm rock" means at least 70% of the drill cuttings being either:
Angular rock fragments, as in the case of crystalline rock; or
Rock fragments composed of individual grains or rock particles that are cemented together to form an aggregate as opposed to a single sediment particle.
“Tremie pipe" means a pipe or hose used to install well construction materials in an annular space or a borehole.
“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.
“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.
“Water table" means the surface of unconfined groundwater where the water pressure is equal to atmospheric pressure.
“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.