PURPOSE: This rule specifically defines words used in Chapter 4 concerning monitoring wells, otherwise the definitions contained in 10 CSR 23-1.010 apply.

1. (1) Concrete means a slurry mixture with a ratio of ninety-four pounds (94 lbs.) of cement, equal volumes of dry sand and gravel, and five to six (5–6) gallons of water from a known safe and uncontaminated source. The ratio of sand and gravel to cement may not exceed three parts to one (3:1).
2. (2) Cone penetrometer means a device used to gather any subsurface information. The device penetrates the ground surface by direct push as a general method of installation.
3. (3) Direct-push well means a monitoring well that is ten feet (10') or greater in depth that is installed by pushing or hammering drive rods as opposed to drilling or augering. Direct-push wells tend to be smaller in diameter than their conventionally drilled counterparts leading to differences in annular space, casing, and sealing dimensions. Various screening or data collection devices, such as a cone penetrometer or lysimeter, may be used in a direct-push well.
4. (4) Extraction well is a monitoring well that is ten feet (10') or greater in depth utilized in the remediation of a site. These include, but are not limited to, the following: wells serving pump and treat systems, including multiwell systems, wells to capture a contaminant plume or alter the direction or magnitude of groundwater movement, and other associated wells. Passive and active methane wells that terminate within landfill trash are exempted from these rules but are regulated by the Missouri Solid Waste Management Program. Passive and active methane and leachate extraction wells that are located outside of trash or extend through trash into the underlying bedrock formations are regulated under these rules.
5. (5) Gas-migration well is a monitoring well that is ten feet (10') or greater in depth and designed for the sampling, detection, and analysis of a gas or vapor that is potentially present or migrating away from a contaminant source.
6. (6) Injection well is a monitoring well that is ten feet (10') or greater in depth into which fluid or other media is injected, to clean, treat, or prevent contamination of groundwater. All other types of injection wells are defined by the Environmental Protection Agency (EPA); these wells may be regulated by other department programs or state agencies.
7. (7) Lysimeter is a device used to measure the percolation of water through soils and/or for determining what soluble constituents are in the fluids moving through the soils.

8. (8) Monitoring well means a well that is ten feet (10') or greater in depth which is constructed during assessment, characterization, and/or remediation of a site to obtain sitespecific water quality, contaminant movement, or geologic or hydrologic data. This includes, but is not limited to:

   1. (A) Extraction wells;
   2. (B) Injection wells;
   3. (C) Soil borings;
   4. (D) Direct-push wells;
   5. (E) Piezometers;
   6. (F) Observation wells;
   7. (G) Gas-migration wells; and
   8. (H) Subsurface penetrations associated with field screening devices such as cone penetrometers and lysimeters.
9. (9) Nested well is a cluster of two (2) or more single riser limited interval monitoring wells installed at different depths in a single borehole with a grout seal separating each screened interval.
10. (10) Nominal diameter means the term used to describe the standard sizes for casing. Depending on the wall thickness, the inside diameter of the casing may be less than or greater than the number indicated. For example, two-inch (2") nominal Schedule 40 polyvinyl chloride (PVC) casing has a standard outside diameter of 2.375 inches, and an inside diameter of 2.067 inches; two-inch (2") nominal Schedule 80 PVC casing has the same outside diameter, but has an inside diameter of only 1.939 inches.
11. (11) Observation well means any monitoring well that is ten feet (10') or greater in depth, in which the screen intersects a water table, for the specific purpose of determining either the elevation of the water table or the physical, chemical, biological, or radiological properties of groundwater. Observation wells constructed in the tank pit used as a part of an underground storage tank leak detection system are excluded from this definition. 10 CSR 23-4
12. (12) Open-hole completion means a monitoring well cased through all overburden material and upper water producing zones, completed in bedrock, with no well screen or filter pack.
13. (13) Piezometer means a monitoring well that is ten feet (10') or greater in depth and used to measure the pressure of a fluid or the degree of compressibility of a substance when subjected to pressure or used to collect water samples for laboratory analysis. It is most commonly a small diameter well used to measure the hydraulic head of groundwater in subsurface water bearing zones. Piezometers used to monitor the geotechnical performance of dams are excluded from the requirements of this rule.
14. (14) Casing means an industry-standard-sized pipe for the purpose of sealing off a specific zone of geology or contaminants.
15. (15) Riser pipe means the pipe extending from the well screen into the surface completion.
16. (16) Shallow monitoring means obtaining groundwater samples from a monitoring well within five feet (5') of ground surface.
17. (17) Temporary well means a monitoring well used for field screening purposes that is ten feet (10') or greater in depth and is plugged within thirty (30) days of completion.

AUTHORITY: sections 256.603, 256.606, and 256.626, RSMo 2000.* Emergency rule filed Nov. 16, 1993, effective Dec. 11, 1993, expired April 9, 1994. Original rule filed Aug. 17, 1993, effective March 10, 1994. Amended: Filed July 13, 1994, effective Jan. 29, 1995. Amended: Filed Nov. 1, 1995, effective June 30, 1996. Amended: Filed Nov. 18, 2010, effective July 30, 2011. *Original authority: 256.603, RSMo 1985, amended 1991; 256.606, RSMo 1991; and 256.626, RSMo 1985, amended 1991.