Authority: IC 14-10-2-4; IC 25-39-4-2; IC 25-39-4-9

Affected: IC 25-39

Sec. 3. (a) This section establishes standards for monitoring wells that are in addition to the general requirements for drilling a well under this article.

(b) A monitoring well shall be equipped with casing. The composition, wall thickness, and nominal diameter of the casing shall be sufficient to allow the well to be used for its intended purpose.

(c) Monitoring well casing shall be new first class material that meets the American Society of Testing Materials (ASTM) standards ASTM A-120 (1984) or ASTM A-53 (1987) or the American Petroleum Institute (API) standards API-5A or API-5L (1987). Thermoplastic pipe shall comply with ASTM F-480 (1981). Well casing shall be as follows:

1. (1) Clean and free of rust, grease, oil, or contaminants and composed of materials that will have minimal impact on the quality of a water sample.
2. (2) Centered in the borehole and free of obstructions so monitoring devices can be lowered into the well.

(d) A monitoring well screen shall be composed of materials that will not corrode or react with chemicals found in the ground water at the site. The well screen slots shall not be hand cut and shall be sized to retain at least ninety percent (90%) of the grain size of the introduced filter pack or natural formation materials if an introduced filter pack is not used. The introduced filter pack shall:

1. (1) be properly sized and graded; and
2. (2) not extend more than two (2) feet above the top of the screen or the uppermost water bearing unit to be monitored in the well annulus unless otherwise approved by the division.

(e) A filter pack seal of bentonite slurry or granular, pelletized, medium grade, or coarse grade crushed bentonite may be placed in the annulus directly above the filter pack or sand grout barrier. The filter pack seal shall:

1. (1) be installed to prevent bridging; and
2. (2) not extend more than two (2) feet above the filter pack or sand grout barrier.

(f) Except as provided in subsection (h), the finished well casing:

1. (1) shall extend at least two (2) feet above the ground level; and

2. (2) if located in a flood plain, must be:

   1. (A) at least two (2) feet above the elevation of the regulatory flood; or
   2. (B) equipped with a watertight cap.

The monitoring well shall be located to protect against surface water ponding, and earthen materials, neat cement, or concrete shall be placed around the well casing to drain surface water from the well.

(g) A monitoring well, located where the casing is susceptible to damage, shall be equipped with a protective outer pipe consisting of a metal casing having a diameter large enough to allow easy access to the well. The protective cover pipe shall be firmly anchored in the ground. Additional protective devices, for example, brightly colored posts around the well, are required where construction equipment or vehicular traffic could damage the well.

(h) A monitoring well must be equipped with a locking cap or cover to prevent unauthorized access. The locking cap may be placed:

1. (1) directly on the well casing; or
2. (2) if required under subsection (g), on the protective cover pipe.

(i) A monitoring well installed so that the top of the well casing is finished at an elevation below the ground surface shall be equipped with a watertight cap. The top of the well casing shall terminate at a depth no greater than one (1) foot below the ground surface and shall be located in a flush mounted protective cover pipe. The flush mounted protective cover pipe shall include each of the following:

1. (1) A watertight one (1) piece or continuous welded metal casing:

   1. (A) at least one (1) foot long; and
   2. (B) having a nominal diameter at least four (4) inches greater than the nominal diameter of the monitoring well.
2. The casing shall be flanged for greater stability if installed in a location likely to be subject to vehicular traffic.
3. (2) A concrete ground surface seal, if an impervious surface, for example, concrete or asphalt, is not present. The ground surface seal shall be installed and extend not more than three (3) feet below the ground surface.

4. (3) A sealed lid that is not more than one-half (1/2) inch higher than the elevation of the ground surface. The sealed lid shall be as follows:

   1. (A) Of a quality to withstand vehicular traffic if installed in a location likely to be subject to vehicular traffic.
   2. (B) Clearly marked with the words "MONITORING WELL" or "MONITOR" and also display the words "DO NOT FILL".

(j) A monitoring well installed by the rotary or auger drilling method shall have a borehole with a diameter at least two (2) inches greater than the nominal diameter of the casing. Except as provided in subsection (e), the well shall be grouted as follows:

1. (1) Granular bentonite may be used to grout a monitoring well if the:

   1. (A) diameter of the borehole is four (4) inches or larger than the nominal diameter of the well casing; and
   2. (B) well is not more than twenty-five (25) feet deep.

2. (2) Except as provided in subdivision (3), the annulus of the monitoring well shall be pressure grouted with neat cement or a bentonite slurry or be grouted with pelletized, medium grade, or coarse grade crushed bentonite from the top of the filter pack or filter pack seal under subsection (e) (for a well installed in unconsolidated materials) or the bottom of the well casing (for a well penetrating bedrock) to the ground surface or to within one (1) foot of the ground surface if a flush mounted protective cover pipe is installed if the:

   1. (A) diameter of the borehole is four (4) inches or larger than the nominal diameter of the well casing; and
   2. (B) well is not more than one hundred (100) feet deep.

3. (3) The annulus of the monitoring well shall be pressure grouted with neat cement or a bentonite slurry from the top of the filter pack or filter pack seal under subsection (e) (for a well installed in unconsolidated materials) or the bottom of the well casing (for a well penetrating bedrock) to the ground surface or to within one (1) foot of the ground surface if a flush mounted protected cover pipe is installed where either the:

   1. (A) diameter of the borehole is less than four (4) inches larger in diameter than the nominal diameter of the well casing; or
   2. (B) well is more than one hundred (100) feet deep.

(k) A monitoring well installed by the cable tool method shall be grouted as follows:

1. (1) The well casing shall be centered in a borehole:

   1. (A) with a diameter of at least two (2) inches greater than the nominal diameter of the casing to be driven;
   2. (B) dug at least three (3) feet, but not more than five (5) feet, below the ground surface; and
   3. (C) filled with granular bentonite or a bentonite slurry during the installation of the casing.
2. Notwithstanding 312 IAC 13-5-1(c), bentonite slurry may be introduced into the borehole annulus by gravity methods during the installation of the well casing.

3. (2) Grouting shall be performed as provided under subsection (i) if a larger diameter:

   1. (A) temporary casing is used to install a smaller diameter permanent well casing; or
   2. (B) borehole is drilled to install a smaller diameter well casing.

(l) A monitoring well installed by the direct push method must be constructed as follows:

1. (1) The well shall be equipped with a prepacked well screen.

2. (2) A sand grout barrier shall:

   1. (A) be placed directly above the prepacked well screen in the annulus between the well casing (riser pipe) and the borehole wall as the probe rods are retracted;
   2. (B) be installed to prevent bridging; and
   3. (C) extend not more than two (2) feet above the top of the prepacked well screen.
3. (3) A filter pack seal may be installed under subsection (e) directly above the sand grout barrier.

4. (4) The remaining annulus between the well casing (riser pipe) and probe rods shall be pressure grouted with neat cement or a bentonite slurry from the top of the sand grout barrier or filter pack seal to:

   1. (A) if a flush-mounted protective pipe is installed, within one (1) foot of the ground surface; or
   2. (B) the ground surface.
5. (5) The probe rods shall be pulled during installation of the grout material.

(m) A monitoring well shall be developed following installation and before water samples are collected. This development shall be accomplished to produce water that is as free as practicable from the following:

1. (1) Sediment.
2. (2) Drill cuttings.
3. (3) Drilling fluids.

If a well is installed to monitor ground water quality, the well shall be adequately developed to present a representative sample of the water quality.

(n) Contaminated drill cuttings, fluids, and surge and wash waters produced in the drilling and development of a monitoring well shall be collected and contained to:

1. (1) prevent contamination of the area; and
2. (2) protect persons who might otherwise come in contact with these materials.

(o) Monitoring well construction and development equipment that comes in contact with contaminated water or contaminated geologic materials shall be cleaned with high-pressure hot water or steam, using inorganic soap or other suitable solvents, and rinsed thoroughly. Contaminated fluids or wash waters shall be collected and contained so that the result is not:

1. (1) contamination of the area; or
2. (2) a hazard to individuals who may come in contact with these materials.

(Natural Resources Commission; 312 IAC 13-8-3; filed Nov 22, 1999, 3:34 p.m.: 23 IR 770; errata filed Dec 30, 1999, 4:02 p.m.: 23 IR 1109; readopted filed Aug 4, 2005, 6:00 p.m.: 28 IR 3661; filed Jul 14, 2006, 1:23 p.m.: 20060809-IR-312050341FRA; readopted filed May 20, 2011, 3:28 p.m.: 20110615-IR-312110002RFA; readopted filed Jul 19, 2017, 3:45 p.m.: 20170816-IR- 312170132RFA; readopted filed May 17, 2023, 10:52 a.m.: 20230614-IR-312230069RFA)