Indiana Administrative Code, Rule 21, Section 21-4 - Ground water monitoring well and piezometer construction and design | Indiana Administrative Code

(a) Ground water monitoring wells and piezometers installed after April 13, 1996, must comply with the requirements of this section.

(b) The following drilling techniques must be used to ensure proper ground water monitoring well construction:

(1) The method of drilling a borehole for a ground water monitoring well or for exploration must be selected to ensure the following:

(A) Subsurface materials are not adversely affected.

(B) Ground water or aquifers are not contaminated or cross-contaminated.

(C) Quality continuous unconsolidated and consolidated material samples are collected.

(D) Equipment sensitivity allows adequate determination of an appropriate screen location.

(E) The diameter of the borehole is at least four (4) inches larger than the diameter of the ground water monitoring well casing and screen, to allow tremie placement of the filter pack and annular sealants.

(F) Drill fluids other than water are to be avoided when possible. However, if fluid additives or lubricants are unavoidable, those used must be demonstrated to be inert and an impact statement must be made regarding the potential impact of any liquids introduced into the borehole on the physical and chemical characteristics of the subsurface and ground water.

(2) All equipment that will encounter formation materials must be decontaminated prior to drilling each new borehole.

(c) Casing and screen materials must comply with the following:

(1) Casing and screen materials must be chosen to:

(A) be resistant to corrosion and degradation in any natural or contaminated environment;

(B) be resistant to physical damage as a result of installation, usage, and time; and

(C) have minimal effect on ground water chemistry with respect to the analytes of concern.

(2) The casing sections must be physically joined and made watertight by:

(A) heat welding;

(B) threading; or

(C) force fitting.

(3) The use of solvents, glues, or other adhesives to join casing sections is prohibited.

(4) For:

(A) ground water monitoring wells, the casing must be two (2) inches in diameter or greater; or

(B) piezometers not to be used for sample collection, the diameter must be one (1) inch or greater.

(5) Except for open borehole bedrock ground water monitoring wells, screens are required for all ground water monitoring wells and piezometers and must include the following:

(A) The screens must be continuous slot wire or machine slotted.

(B) Slot size must retain ninety percent (90%) to one hundred percent (100%) of the filter pack material.

(C) Screen lengths must be not less than two (2) feet and not greater than ten (10) feet unless approved by the commissioner based on site-specific conditions.

(6) Ground water monitoring well and piezometer casing and screens must be cleaned prior to introduction into the borehole to prevent manufacturers' residues and coatings from contaminating the borehole or aquifer.

(7) Screen and casing must be properly centered in the borehole prior to filling the annulus.

(d) Procedures for collecting, analyzing, and storing core samples must comply with the following:

(1) Continuous downhole samples of the unconsolidated and consolidated materials must be collected in all ground water monitoring well and piezometer boreholes unless the ground water monitoring wells or piezometers are replacement monitoring wells or piezometers under section 1(g)(2)(B) of this rule [of this rule]. For monitoring well clusters or piezometer clusters, continuous samples must be collected from the surface to the base of the deepest monitoring well or piezometer; other monitoring wells or piezometers within the cluster must be sampled at all significant stratigraphic changes and at the screened interval. Samples must not be combined into composite samples for classification or testing.

(2) All procedures regarding testing and sampling must be described to the commissioner in writing.

(3) The owner, operator, or permittee shall:

(A) retain all borehole samples in labeled containers or labeled core boxes that are securely stored and accessible for a period of:

(i) seven (7) years after the samples are collected; or

(ii) seven (7) years after permit issuance; whichever occurs later;

(B) notify the commissioner, in writing, of the location of the core sample storage; and

(C) ensure that core samples are available for inspection, by the commissioner or by a representative of the department, at all reasonable times or during normal operating hours.

(4) Each significant stratum encountered in the borehole must have the following analysis performed and testing results must be identified with respect to sample elevations and borehole:

(A) Complete grain size using the following techniques:

(i) Sieve.

(ii) Hydrometer.

(B) Cation exchange capacity.

(C) Hydraulic conductivity if the information in this subsection for that strata is not available to the satisfaction of the commissioner.

(e) The ground water monitoring well or piezometer annulus must be filled as follows when drilling is complete:

(1) The annular space from six (6) inches below the well screen to two (2) feet above the well screen must be filled with a filter pack consisting of inert sand or gravel and shall comply with the following:

(A) A uniform grain size must be chosen to reflect three (3) to five (5) times the average fifty percent (50%) retained size of the formation material unless this filter pack grain size would impede adequate flow of ground water into the ground water monitoring well or piezometer. Should this happen, a filter pack grain size shall be used that allows ground water flow into the monitoring well or piezometer and prevents as much silt infiltration as possible.

(B) Natural material may be an acceptable constituent of the filter pack if slump is unavoidable.

(C) The filter pack in a bedrock monitoring well or piezometer is optional. However, if used, the filter pack must be of a nonreactive coarse sand or gravel.

(D) The upper one (1) to two (2) feet of the filter pack must be of fine, inert sand to prevent infiltration of seal materials.

(E) The filter pack must be emplaced without bridging, preferably by tremie pipe, or other methods as approved by the commissioner to ensure the integrity of the filter pack.

(2) A bentonite seal of at least three (3) feet must be emplaced by tremie pipe in the annular space directly above the filter pack.

(3) The annular space from the bentonite seal to one (1) foot below the frost line must be tremied with a grout of bentonite, cement/bentonite, or other shrinkage-compensated, low permeability fill and shall include the following:

(A) All bentonite and cements must be mixed to the manufacturer's specifications.

(B) Full hydration, curing, or setting of the bentonite seal must occur prior to further backfilling as required by this subdivision.

(4) A surface seal of neat cement or concrete must be installed in the remaining borehole annular space above the intermediate fill, including the following:

(A) The apron of the surface seal must be designed to prevent ponding and infiltration by extending at least two and five-tenths (2.5) feet from the ground water monitoring well casing.

(B) The apron must slope at least fifteen (15) degrees outward.

(C) A locking protective metal casing must be installed around the ground water monitoring well casing and be anchored below the frost line in the surface seal.

(D) A vent hole or vented cap must be placed at the top of the ground water monitoring well or piezometer casing to allow accurate piezometric variation and to prevent gas build-up.

(E) The annular space between the ground water monitoring well casing and the protective metal casing must be neat cement filled to a level at least one (1) inch higher than that of the surrounding apron.

(F) A drainage hole must be drilled in the protective metal casing immediately above the cement fill specified in clause (E).

(G) The remaining annular space between the ground water monitoring well casing and the protective metal casing must be filled with a fine gravel.

(H) A weather resistant lock must be dedicated to the ground water monitoring well and must be serviced twice a year and when the ground water monitoring well is sampled.

(I) A permanent unique identification must be affixed to each ground water monitoring well and the identification must be visible.

(J) Three (3) foot bumper guards or other suitable protection may be required by the commissioner to prevent vehicular traffic from damaging the protective metal casing.

(f) The permittee shall provide ten (10) days' advance notification to the department of the date and time of the installation of the monitoring wells or piezometers.

(g) Development of ground water monitoring wells must occur as soon as possible after the seal and grout have set and must conform with the following:

(1) All ground water monitoring wells must be developed in such a way as to:

(A) allow free entry of formation water;

(B) minimize turbidity of the sample; and

(C) minimize clogging of the monitoring wells.

(2) Development methods chosen must be appropriate for the stratigraphic conditions.

(3) An in situ hydraulic conductivity test must be performed after the ground water monitoring well has been properly developed.

(h) Diagrammatical borehole drilling logs for all ground water monitoring wells and piezometers must be of similar scale and include the following information:

(1) The monitoring well or piezometer and borehole identification.

(2) The date of drilling.

(3) The method of drilling.

(4) The borehole diameter.

(5) The method of obtaining consolidated material and unconsolidated material.

(6) The type of any drill fluids, fluid additives, or lubricants other than water that have been used.

(7) Penetration measurements, such as hammer blow counts, penetrometer measurements, or other acceptable penetration measurements.

(8) The sample recovery measured to the nearest one-tenth (0.1) foot.

(9) Consolidated material and unconsolidated material field descriptions, including the following information:

(A) Lithology and sedimentology.

(B) Mineralogy.

(C) Degree of cementation.

(D) Degree of moisture.

(E) Color as referenced from soil color charts such as the Munsell soil charts.

(F) Grain size and textural classification of unconsolidated samples as referenced from the United States Department of Agriculture (USDA) textural classification charts. Grain-size divisions shall be based on a modified form of the Wentworth grain-size scale defined under 329 IAC 10-2-206.3. A determination shall be made of the percentage and grades of coarse fragments greater than two (2) millimeters in size based on 329 IAC 10-2-206.3 in addition to the USDA textural classification. Consolidated samples must be described using accepted geological classification systems and nomenclature. A clear description of the classification system used must be included with the logs.

(G) Any other physical characteristics of the consolidated material and unconsolidated material such as scent, staining, fracturing, and solution features.

(H) The percent recovery and rock quality designation.

(I) Other primary or secondary features.

(J) Drilling observations and appropriate details required for unconsolidated drilling logs.

(K) A clear photograph of all consolidated cores, labelled with:

(i) the date the photograph was taken;

(ii) the sample interval;

(iii) the reference scale;

(iv) the reference color scale; and

(v) the identification of the borehole.

(L) Interval of continuous samples and unconsolidated material test data.

(10) Distance to and depth of any water bearing zones, measured to the nearest one-hundredth (0.01) foot.

(11) Static water elevations measured to the nearest one-hundredth (0.01) foot and indicating the dates and times the measurements were taken.

(12) The elevation of permanent monitoring wells or piezometers at the ground surface to the nearest one-tenth (0.1) foot, with the referenced measuring mark measured to the nearest one-hundredth (0.01) foot relative to the National Geodetic Vertical Datum.

(13) The horizontal location of permanent monitoring wells or piezometers measured to the nearest thirty (30) cm using Universal Transverse Mercator (UTM) coordinates.

(14) Total borehole depth and elevation measured to the nearest one-hundredth (0.01) foot.

(15) Elevation range of screened interval measured to the nearest one-hundredth (0.01) foot.

(i) The construction details and diagrams of all pertinent ground water monitoring wells must be recorded on logs and include the following information:

(1) The monitoring well identification and UTM coordinates as described under subsection (h)(13).

(2) The composition of monitoring well and protective casing materials.

(3) The type of joints and couplings between monitoring well casing segments.

(4) The elevations of the ground surface to the nearest one-tenth (0.1) foot and of the referenced measuring mark at the top of the monitoring well casing measured to the nearest one-hundredth (0.01) foot relative to the National Geodetic Vertical Datum.

(5) The diameter of monitoring well casing and borehole.

(6) The elevation of the bottom of the borehole and the depth of the borehole measured to the nearest one-hundredth (0.01) foot.

(7) The screen slot size.

(8) The elevation range of the screened interval measured to the nearest one-hundredth (0.01) foot.

(9) The screen length measured to the nearest one-hundredth (0.01) foot.

(10) Methods of installation of the annular fill.

(11) The elevation range and the depth of the filter pack measured to the nearest one-hundredth (0.01) foot.

(12) The length of the filter pack.

(13) The grain size and composition of all filter pack materials and the fifty percent (50%) retained size of the formation material when used to determine the grain size of the filter pack materials.

(14) The elevation and depth range of the bentonite seal above the filter pack measured to the nearest one-hundredth (0.01) foot.

(15) The thickness of the bentonite seal above the filter pack.

(16) The composition of annular fill.

(17) The elevation range, depth range, and thickness of annular fill measured to the nearest one-hundredth (0.01) foot.

(18) The composition and design of the surface seal.

(19) The design and composition of materials used for the protection of the monitoring well casing.

(j) The construction details and diagram of each piezometer must be recorded on logs and include the following:

(1) Piezometer identification number and UTM coordinates.

(2) Elevation of the top of the piezometer casing.

(3) Height of piezometer casing above the ground.

(4) Elevation of the ground surface.

(5) Elevation and depth to the bottom of the borehole.

(6) Diameter of piezometer casing and borehole.

(7) Elevation and depth to the bottom and top of the piezometer screen.

(8) Length of piezometer casing.

(9) Composition of piezometer casing materials and piezometer screen material.

(10) Length of piezometer screen.

(11) Screen slot size.

(12) Type of joints or couplings, or both, between casing segments.

(13) Elevation and depth to the top and bottom of the gravel filter pack surrounding the piezometer screen.

(14) Length of the gravel filter pack.

(15) Elevation and depth of the bottom of the piezometer casing.

(16) Elevation and depth of the top and bottom of the seal above the gravel filter pack.

(17) The grain size and composition of all filter pack materials and the fifty percent (50%) retained size of the formation material when used to determine the grain size of the filter pack materials.

(18) Thickness of the seal above the gravel filter pack.

(19) Elevation and depth of the annular seal above the gravel filter pack seal.

(20) Thickness of the annular seal.

(21) Material used for the annular seal.

(22) Method of installation of the annular seal.

(23) The composition and design of the surface seal.