ASTM D5092/D5092M-16

Standard Practice for Design and Installation of Groundwater Monitoring Wells

SIGNIFICANCE AND USE
4.1 This practice for the design and installation of groundwater monitoring wells will promote (1) efficient and effective site hydrogeological characterization; (2) durable and reliable well construction; and (3) acquisition of representative groundwater quality samples, groundwater levels, and hydraulic conductivity testing data from monitoring wells. The practices established herein are affected by governmental regulations and by site-specific geological, hydrogeological, climatological, topographical, and subsurface geochemical conditions. To meet these geoenvironmental challenges, this practice promotes the development of a conceptual hydrogeologic model prior to monitoring well design and installation.
Note 1: This practice presents a design for monitoring wells that will be effective in the majority of formations. This practice is in general accordance with other national and state guidance documents on well construction (ANSI/NGWA-01-14 (1)4 and California EPA (2)) however; national, state, or local design regulations may control design and installation.  
4.2 A properly designed and installed groundwater monitoring well provides essential information on one or more of the following subjects:  
4.2.1 Formation geologic and hydraulic properties;  
4.2.2 Potentiometric surface of a particular hydrologic unit(s);  
4.2.3 Water quality with respect to various indicator parameters; and  
4.2.4 Water chemistry with respect to a contaminant release.
Note 2: The quality of the result produced by this standard is dependent on the competence of the personnel performing it, and the suitability of the equipment and facilities used. Agencies that meet the criteria of Practice D3740 are generally considered capable of competent and objective testing/sampling/inspection/etc. Users of this standard are cautioned that compliance with Practice D3740 does not in itself assure reliable results. Reliable results depend on many factors; Practice D3740 provides a means of...
SCOPE
1.1 This practice describes a methodology for designing and installing conventional (screened and filter-packed) groundwater monitoring wells suitable for formations ranging from unconsolidated aquifers (that is, sands and gravels) to granular materials having grain-size distributions with up to 50 % passing a #200 sieve and as much as 20 % clay-sized material (that is, silty fine sands with some clay). Formations finer than this (that is, silts, clays, silty clays, clayey silts) can be monitored but the well may not yield sufficient water required for sampling, and fine filter pack and screen requirements are difficult and costly to install. Use of coarser filter/screens in fine formations will result in wells with unstable filter packs and associated elevated sample turbidity that may adversely affect sample accuracy and data quality objectives. This practice is not applicable in fractured or karst rock conditions, but may be applicable for other porous rock formations.  
1.2 The recommended monitoring well design and installation procedures presented in this practice are based on the assumption that the objectives of the program are to obtain representative groundwater samples and other representative groundwater data from a targeted zone of interest in the subsurface defined by site characterization.  
1.3 This practice when used on coarse grained sand and gravel aquifers, in combination with proper well development (D5521), proper groundwater sampling procedures (D4448), and proper well maintenance and rehabilitation (D5978), will permit acquisition of groundwater samples free of artifactual turbidity, eliminate siltation of wells between sampling events, and permit acquisition of accurate groundwater levels and hydraulic conductivity test data from the zone screened by the well. For wells installed in fine-grained formation materials, it is generally necessary to use much finer pre-packed well screens (6.3.3.2) a...

General Information

• Status: Published
• Publication Date: 14-Nov-2016
• ICS: 13.060.10 - Water of natural resources
• Technical Committee: D18 - Soil and Rock
• Drafting Committee: D18.21 - Groundwater and Vadose Zone Investigations

Relations

• Replaces: ASTM D5092-04(2010)e1 - Standard Practice for Design and Installation of Groundwater Monitoring Wells
• Effective Date: 15-Nov-2016
• Refers: ASTM D3740-23 - Standard Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used in Engineering Design and Construction
• Effective Date: 01-Nov-2023
• Refers: ASTM D5778-20 - Standard Test Method for Electronic Friction Cone and Piezocone Penetration Testing of Soils
• Effective Date: 01-Jun-2020
• Refers: ASTM D1129-13(2020)e2 - Standard Terminology Relating to Water
• Effective Date: 01-May-2020
• Refers: ASTM D5088-20 - Standard Practice for Decontamination of Field Equipment Used at Waste Sites
• Effective Date: 01-May-2020
• Refers: ASTM D5787-20 - Standard Practice for Monitoring Well Protection At or Near Land Surface
• Effective Date: 01-Jan-2020
• Refers: ASTM D6432-19 - Standard Guide for Using the Surface Ground Penetrating Radar Method for Subsurface Investigation
• Effective Date: 15-Nov-2019
• Refers: ASTM D6286-19 - Standard Guide for Selection of Drilling and Direct Push Methods for Geotechnical and Environmental Subsurface Site Characterization
• Effective Date: 01-Oct-2019
• Refers: ASTM D3740-19 - Standard Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used in Engineering Design and Construction
• Effective Date: 01-Oct-2019
• Refers: ASTM D6167-19 - Standard Guide for Conducting Borehole Geophysical Logging: Mechanical Caliper
• Effective Date: 01-May-2019
• Refers: ASTM D4448-01(2019) - Standard Guide for Sampling Ground-Water Monitoring Wells
• Effective Date: 01-Feb-2019
• Refers: ASTM D6274-18 - Standard Guide for Conducting Borehole Geophysical Logging - Gamma
• Effective Date: 15-Dec-2018
• Refers: ASTM D6431-18 - Standard Guide for Using the Direct Current Resistivity Method for Subsurface Site Characterization
• Effective Date: 01-Feb-2018
• Refers: ASTM D5753-18 - Standard Guide for Planning and Conducting Geotechnical Borehole Geophysical Logging
• Effective Date: 01-Feb-2018
• Refers: ASTM D6639-18 - Standard Guide for Using the Frequency Domain Electromagnetic Method for Subsurface Site Characterizations
• Effective Date: 01-Feb-2018

Overview

ASTM D5092/D5092M-16 from ASTM International is a key standard providing comprehensive guidance for the design and installation of groundwater monitoring wells. This standard practice is intended to promote efficient site hydrogeological characterization, ensure durable well construction, and enable the acquisition of representative groundwater samples and data. Compliance with ASTM D5092/D5092M-16 helps organizations achieve high-quality, reliable groundwater monitoring results, which are essential for environmental site assessments, regulatory compliance, and contamination investigations.

Key Topics

• Site Characterization
  The standard emphasizes conducting a thorough site-specific assessment of geologic, hydrologic, and geochemical conditions. A conceptual hydrogeologic model should be developed prior to well design and installation.

• Well Design Principles
  ASTM D5092/D5092M-16 applies primarily to conventional (screened and filter-packed) monitoring wells installed in unconsolidated aquifers, such as sands and gravels, and granular formations with up to 20% clay-sized material.

• Selection of Materials
  Proper material selection for risers, screens, and filter packs ensures that well construction does not alter groundwater chemistry and that samples are reliable. Only inert materials should be used in contact with groundwater.

• Installation Methodology
  The standard describes general practices for drilling, installing, and developing conventional monitoring wells, including procedures for filter pack placement, annular seal installation, and well screen selection.

• Quality Assurance
  The reliability of groundwater data is strongly linked to the skill of personnel, the suitability of equipment, and the implementation of robust sampling procedures. The use of certified or qualified contractors is recommended.

• Limitations
  ASTM D5092/D5092M-16 is not recommended for fractured or karst rocks but is applicable to other porous rock formations. Special consideration is needed for fine-grained formations and regulatory requirements may override aspects of this standard.

Applications

Groundwater monitoring wells constructed according to ASTM D5092/D5092M-16 are widely used in:

• Environmental Site Assessments
  Wells provide essential data on groundwater flow, contamination plumes, and aquifer properties, informing risk assessments and remediation strategies.

• Regulatory Compliance
  Installations in adherence with this standard help meet federal, state, and local environmental regulations for groundwater monitoring at landfills, industrial sites, and remediation projects.

• Hydrogeological Investigations
  The practice facilitates the accurate characterization of formation geology, hydraulic properties, groundwater levels (potentiometric surfaces), and water quality parameters.

• Contaminant Studies
  High-integrity wells constructed by this standard enable reliable sampling for various chemical indicators and contaminants. This supports effective decision making in groundwater remediation.

• Filter Pack and Screen Design
  Properly designed filter packs and well screens reduce turbidity and enable the collection of representative water samples, minimizing sample bias due to sedimentation or well construction artifacts.

Related Standards

ASTM D5092/D5092M-16 references and complements several other ASTM standards and industry guidelines, including:

• ASTM D3740 – Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock
• ASTM D5521 – Guide for Development of Groundwater Monitoring Wells in Granular Aquifers
• ASTM D4448 – Guide for Sampling Ground-Water Monitoring Wells
• ASTM D5978 – Guide for Maintenance and Rehabilitation of Groundwater Monitoring Wells
• ASTM D6724/D6725 – Guides for Installation of Direct Push Groundwater Monitoring Wells
• ANSI/NGWA-01-14 – American National Standard for Water Well Construction
• California EPA Guidelines – State-specific regulations for well construction

Organizations should always verify and comply with any additional national, state, or local regulations and standards relevant to groundwater monitoring well construction.

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For more detailed information or to obtain ASTM D5092/D5092M-16, visit www.astm.org.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D5092/D5092M − 16
Standard Practice for
Design and Installation of Groundwater Monitoring Wells
This standard is issued under the fixed designation D5092/D5092M; the number immediately following the designation indicates the
year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last
reapproval. A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope* passive sampling devices (D7929) are two means to minimize
the potential sample bias associated with turbidity.
1.1 Thispracticedescribesamethodologyfordesigningand
1.4 This practice applies primarily to well design and
installing conventional (screened and filter-packed) groundwa-
ter monitoring wells suitable for formations ranging from installation methods used in drilled boreholes. Other standards,
including Guide D6724 and Practice D6725, cover installation
unconsolidated aquifers (that is, sands and gravels) to granular
materials having grain-size distributions with up to 50 % of monitoring wells using direct-push methods.
passing a #200 sieve and as much as 20 % clay-sized material
1.5 Units—The values stated in either inch-pound units or
(that is, silty fine sands with some clay). Formations finer than
SI units [presented in brackets] are to be regarded separately as
this (that is, silts, clays, silty clays, clayey silts) can be
standard. The values stated in each system may not be exact
monitored but the well may not yield sufficient water required
equivalents;therefore,eachsystemshallbeusedindependently
for sampling, and fine filter pack and screen requirements are
of the other. Combining values from the two systems may
difficult and costly to install. Use of coarser filter/screens in
resultinnon-conformancewiththestandard.Equivalentvalues
fine formations will result in wells with unstable filter packs
given in parentheses are shown for mix designs and sieves
and associated elevated sample turbidity that may adversely
sizes.
affect sample accuracy and data quality objectives. This
1.5.1 Sieve Designations (Specification E11) are identified
practice is not applicable in fractured or karst rock conditions,
using the “alternate” system, for example, #40, #200 sieve etc.
but may be applicable for other porous rock formations.
with nominal opening size in inches and particle sizes in mm.
See Specification E11 for standard metric sieve sizes.
1.2 The recommended monitoring well design and installa-
1.5.2 Well screen slots are expressed in inches and the
tion procedures presented in this practice are based on the
metric equivalent is given in the terminology section and when
assumption that the objectives of the program are to obtain
necessary in the standard (see 3.3.6).
representative groundwater samples and other representative
groundwater data from a targeted zone of interest in the
1.6 All observed and calculated values shall conform to the
subsurface defined by site characterization.
guidelines for significant digits and rounding established in
Practice D6026, unless superseded by this standard.
1.3 This practice when used on coarse grained sand and
gravel aquifers, in combination with proper well development
1.7 This standard does not purport to address all of the
(D5521), proper groundwater sampling procedures (D4448),
safety concerns, if any, associated with its use. It is the
and proper well maintenance and rehabilitation (D5978), will
responsibility of the user of this standard to establish appro-
permit acquisition of groundwater samples free of artifactual
priate safety and health practices and determine the applica-
turbidity, eliminate siltation of wells between sampling events,
bility of regulatory limitations prior to use.
and permit acquisition of accurate groundwater levels and
1.8 This practice offers a set of instructions for performing
hydraulic conductivity test data from the zone screened by the
one or more specific operations. This document cannot replace
well. For wells installed in fine-grained formation materials, it
education or experience and should be used in conjunction
is generally necessary to use much finer pre-packed well
with professional judgment. Nat all aspects of this practice may
screens (6.3.3.2) and/or employ sampling methods that mini- be applicable in all circumstances. This ASTM standard is not
mize screen intake flow velocity, and disturbance of the well
intended to represent or replace the standard of care by which
column including suspension of settled solids in the well. the adequacy of a given professional service must be judged,
Using low-flow purging and sampling techniques (D6771)or
nor should this document be applied without consideration of
a project’s many unique aspects. The word “Standard” in the
title of this document means only that the document has been
This practice is under the jurisdiction of ASTM Committee D18 on Soil and
approved through the ASTM consensus process.
Rock and is the direct responsibility of Subcommittee D18.21 on Groundwater and
Vadose Zone Investigations.
1.9 This international standard was developed in accor-
Current edition approved Nov. 15, 2016. Published December 2016. Originally
ɛ1
dance with internationally recognized principles on standard-
approved in 1990. Last previous edition approved in 2010 as D5092–04(2010) .
DOI: 10.1520/D5092_D5092M-16. ization established in the Decision on Principles for the
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5092/D5092M − 16
Development of International Standards, Guides and Recom- Subsurface Investigation
mendations issued by the World Trade Organization Technical D5778 Test Method for Electronic Friction Cone and Piezo-
Barriers to Trade (TBT) Committee.
cone Penetration Testing of Soils
D5781 Guide for Use of Dual-Wall Reverse-Circulation
2. Referenced Documents
Drilling for Geoenvironmental Exploration and the Instal-
2.1 ASTM Standards:
lation of Subsurface Water-Quality Monitoring Devices
C150 Specification for Portland Cement
D5782 Guide for Use of Direct Air-Rotary Drilling for
C294 Descriptive Nomenclature for Constituents of Con-
Geoenvironmental Exploration and the Installation of
crete Aggregates
Subsurface Water-Quality Monitoring Devices
D422 Test Method for Particle-SizeAnalysis of Soils (With-
D5783 Guide for Use of Direct Rotary Drilling with Water-
drawn 2016)
Based Drilling Fluid for Geoenvironmental Exploration
D653 Terminology Relating to Soil, Rock, and Contained
and the Installation of Subsurface Water-Quality Monitor-
Fluids
ing Devices
D1129 Terminology Relating to Water
D5784 Guide for Use of Hollow-Stem Augers for Geoenvi-
D1452 Practice for Soil Exploration and Sampling byAuger
ronmental Exploration and the Installation of Subsurface
Borings
Water-Quality Monitoring Devices
D1586 Test Method for Standard PenetrationTest (SPT) and
D5787 Practice for Monitoring Well Protection
Split-Barrel Sampling of Soils
D5872 Guide for Use of Casing Advancement Drilling
D1587 Practice for Thin-Walled Tube Sampling of Fine-
Methods for Geoenvironmental Exploration and Installa-
Grained Soils for Geotechnical Purposes
tion of Subsurface Water-Quality Monitoring Devices
D2113 Practice for Rock Core Drilling and Sampling of
D5875 Guide for Use of Cable-Tool Drilling and Sampling
Rock for Site Exploration
Methods for Geoenvironmental Exploration and Installa-
D2487 Practice for Classification of Soils for Engineering
Purposes (Unified Soil Classification System) tion of Subsurface Water-Quality Monitoring Devices
D2488 Practice for Description and Identification of Soils D5876 Guide for Use of Direct Rotary Wireline Casing
(Visual-Manual Procedures)
Advancement Drilling Methods for Geoenvironmental
D3282 Practice for Classification of Soils and Soil-
Exploration and Installation of Subsurface Water-Quality
Aggregate Mixtures for Highway Construction Purposes
Monitoring Devices
D3550 Practice for Thick Wall, Ring-Lined, Split Barrel,
D5978 Guide for Maintenance and Rehabilitation of
Drive Sampling of Soils
Groundwater Monitoring Wells
D3740 Practice for Minimum Requirements for Agencies
D6001 Guide for Direct-Push Groundwater Sampling for
Engaged in Testing and/or Inspection of Soil and Rock as
Environmental Site Characterization
Used in Engineering Design and Construction
D6026 Practice for Using Significant Digits in Geotechnical
D4448 Guide for Sampling Ground-Water MonitoringWells
Data
D5088 Practice for Decontamination of Field Equipment
D6067 Practice for Using the Electronic Piezocone Pen-
Used at Waste Sites
etrometer Tests for Environmental Site Characterization
D5299 Guide for Decommissioning of Groundwater Wells,
D6167 Guide for Conducting Borehole Geophysical Log-
Vadose Zone Monitoring Devices, Boreholes, and Other
ging: Mechanical Caliper
Devices for Environmental Activities
D6169 Guide for Selection of Soil and Rock Sampling
D5434 Guide for Field Logging of Subsurface Explorations
Devices Used With Drill Rigs for Environmental Investi-
of Soil and Rock
gations
D5518 GuideforAcquisitionofFileAerialPhotographyand
D6274 Guide for Conducting Borehole Geophysical Log-
Imagery for Establishing Historic Site-Use and Surficial
ging - Gamma
Conditions
D5521 Guide for Development of Groundwater Monitoring D6282 Guide for Direct Push Soil Sampling for Environ-
Wells in Granular Aquifers mental Site Characterizations
D5608 Practices for Decontamination of Sampling and Non
D6285 Guide for Locating Abandoned Wells
Sample Contacting Equipment Used at Low Level Radio-
D6286 Guide for Selection of Drilling Methods for Environ-
active Waste Sites
mental Site Characterization
D5753 Guide for Planning and Conducting Borehole Geo-
D6429 Guide for Selecting Surface Geophysical Methods
physical Logging
D6430 Guide for Using the Gravity Method for Subsurface
D5777 Guide for Using the Seismic Refraction Method for
Investigation
D6431 Guide for Using the Direct Current Resistivity
2 Method for Subsurface Investigation
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM D6432 Guide for Using the Surface Ground Penetrating
Standards volume information, refer to the standard’s Document Summary page on
Radar Method for Subsurface Investigation
the ASTM website.
3 D6519 Practice for Sampling of Soil Using the Hydrauli-
The last approved version of this historical standard is referenced on
www.astm.org. cally Operated Stationary Piston Sampler
D5092/D5092M − 16
D6639 Guide for Using the Frequency Domain Electromag- counteract caving, to advance the borehole, or to isolate the
netic Method for Subsurface Investigations (Withdrawn zone being monitored, or any combination of these.
2017)
3.1.8 casing, protective, n—in drilling, a section of larger
D6640 Practice for Collection and Handling of Soils Ob-
diameter pipe that is placed over the upper end of a smaller
tained in Core Barrel Samplers for Environmental Inves-
diameter monitoring well riser or casing to provide structural
tigations
protection to the well, to prevent damage to the well, and to
D6724 Guide for Installation of Direct Push Groundwater
restrict unauthorized access into the well.
Monitoring Wells
3.1.9 casing, surface, n—in drilling, pipe used to stabilize a
D6725 Practice for Direct Push Installation of Prepacked
borehole near the surface during the drilling of a borehole that
Screen Monitoring Wells in Unconsolidated Aquifers
may be left in place or removed once drilling is completed.
D6771 Practice for Low-Flow Purging and Sampling for
3.1.10 caving; sloughing, v—in drilling, the inflow of un-
Wells and Devices Used for Ground-Water Quality Inves-
consolidated material into a borehole that occurs when the
tigations (Withdrawn 2011)
borehole walls lose their cohesiveness.
D6914 Practice for Sonic Drilling for Site Characterization
and the Installation of Subsurface Monitoring Devices
3.1.11 cement, n—in drilling, commonly known as Portland
D7242 Practice for Field Pneumatic Slug (Instantaneous
cement. A mixture that consists of calcareous, argillaceous, or
Change in Head) Tests to Determine Hydraulic Properties
other silica-, alumina-, and iron-oxide-bearing materials that is
of Aquifers with Direct Push Groundwater Samplers
manufactured and formulated to produce various types which
D7929 Guide for Selection of Passive Techniques for Sam-
are defined in Specification C150. Portland cement is consid-
pling Groundwater Monitoring Wells
ered a hydraulic cement because it must be mixed with water
D8037 Practice for Direct Push Hydraulic Logging Profiling
to form a cement-water paste that has the ability to harden and
Variations of Permeability Soils
develop strength even if cured under water.
E11 Specification for Woven Wire Test Sieve Cloth and Test
3.1.12 centralizer, n—in drilling, a device that assists in the
Sieves
centering of a casing or riser within a borehole or another
F480 Specification for Thermoplastic Well Casing Pipe and
casing.
Couplings Made in Standard Dimension Ratios (SDR),
3.1.13 confining unit, n—in hydrogeology, a body of rela-
SCH 40 and SCH 80
tively low hydraulic conductivity formation material strati-
graphically adjacent to one or more aquifers.
3. Terminology
3.1.13.1 Discussion—Synonymous with or may include for-
3.1 Definitions:
mations that are considered to be “aquiclude,” “aquitard,” and
3.1.1 For definitions of common technical terms in this
“aquifuge.”
standard, refer Terminology D653.
3.1.14 flush joint or flush coupled, n—in drilling, casing or
3.1.2 artifactual turbidity, n—in wells, filters, particulate
riser with ends threaded such that a consistent inside and
matter that is not naturally mobile in the groundwater system
outside diameter is maintained across the threaded joints or
andthatisproducedinsomewaybythegroundwatersampling
couplings.
process.
3.1.2.1 Discussion—May consist of particles introduced to 3.1.15 gravel pack, n—in wells, filters, common term used
to refer to the primary filter pack of a well (see primary filter
the subsurface during drilling or well construction, sheared
from the target monitoring zone during pumping or bailing the pack).
well, or produced by exposure of groundwater to atmospheric
3.1.16 hydrologic unit, n—in geology, hydrogeology, geo-
conditions.
logic strata that can be distinguished on the basis of capacity to
yieldandtransmitfluids.Aquifersandconfiningunitsaretypes
3.1.3 ballast, n—in drilling, materials used to provide sta-
of hydrologic units. Boundaries of a hydrologic unit may not
bility to a buoyant object (such as casing within a water-filled
necessarily correspond either laterally or vertically to lith-
borehole).
ostratigraphic formations.
3.1.4 borehole, n—in drilling, an open or uncased subsur-
face hole, generally circular in plain view, created by drilling. 3.1.17 neat cement, n—in grouting, a mixture of Portland
cement (Specification C150) and water.
3.1.5 borehole log, n—in drilling, the record of geologic
units penetrated, drilling progress, depth, water level, sample 3.1.18 piezometer, n—in wells, hydrogeology, a small-
diameter well with a very short screen that is used to measure
recovery, volumes, and types of materials used, and other
significant facts regarding the drilling and/or installation of an changes in hydraulic head, usually in response to pumping a
nearby well. Synonymous with observation well.
exploratory borehole or well.
3.1.6 bridge, n—in drilling, an obstruction within the annu- 3.1.19 piping, n—the progressive removal of soil particles
lusthatmaypreventcirculationorproperplacementofannular from a mass by percolating water, leading to the development
fill materials. of channels.
3.1.7 casing, n—in drilling, pipe, finished in sections with 3.1.20 primary filter pack, n—in wells, a clean silica sand or
either threaded connections or beveled edges to be field sand and gravel mixture of selected grain size and gradation
welded, which is installed temporarily or permanently either to that is installed in the annular space between the borehole wall
D5092/D5092M − 16
and the well screen, extending an appropriate distance above 3.1.33 well completion diagram, n—in wells, a record that
the screen, for the purpose of retaining and stabilizing the illustrates the details of a well installation.
particles from the adjacent formation(s). The term is used in
3.1.34 well screen, n—in wells, a device used to retain the
place of gravel pack.
primary or natural filter pack; usually a cylindrical pipe with
openings of a uniform width, orientation, and spacing.
3.1.21 PTFE tape, n—in drilling, joint sealing tape com-
posed of polytetrafluoroethylene.
3.2 Terms Referenced in D1129, Committee D19 on Water:
3.1.22 riser, n—in wells, the pipe or well casing extending 3.2.1 turbidity, n—expression of the optical properties of a
from the well screen to just above or below the ground surface. sample that causes light rays to be scattered and absorbed
rather than transmitted in straight lines through the sample.
3.1.23 secondary filter pack, n—in wells, a clean, uniformly
(Turbidity of water is caused by the presence of suspended and
graded sand that is placed in the annulus between the primary
dissolved matter such as clay, silt, finely divided organic
filter pack and the overlying seal, or between the seal and
matter, plankton, other microscopic organisms, organic acids,
overlyinggroutbackfill,orboth,topreventintrusionoftheseal
and dyes.)
or grout, or both, into the primary filter pack.
3.2.1.1 Discussion—The D19 definition is related to mea-
3.1.24 sediment sump, n—in wells,ablankextensionofpipe
surement of turbidity. For the purpose of this standard, turbid-
or well casing, closed at the bottom, beneath the well screen
ity is cloudiness or haziness in a fluid caused by the presence
used to collect fine-grained material from the filter pack and
of small suspended solids that are otherwise imperceptible to
adjacent formation materials during the process of well devel-
the naked eye.
opment. Synonymous with rat trap or tail pipe.
3.3 Definitions of Terms Specific to This Standard:
3.1.25 static water level, n—in hydrogeology, the elevation
3.3.1 annular space; annulus, n—the space between two
of the top of a column of water in a monitoring well or
concentric strings of casing, or between the casing and the
piezometer that is not influenced by pumping or conditions
borehole wall. This includes the space(s) between multiple
related to well installation, or hydraulic testing.
strings of casing in a borehole installed either concentrically or
3.1.26 tamper, n—in piezometers and wells, a heavy cylin- adjacent to one another
drical metal section of tubing that is operated on a wire rope or
3.3.2 grout (monitoring wells), n—a low-permeability ma-
cable. It either slips over the riser and fits inside the casing or
terialplacedintheannulusbetweenthewellcasingorriserand
borehole annulus, or fits between the riser and annulus. It is
the borehole wall (in a single-cased monitoring well), or
generally used to tamp annular sealants or filter pack materials
between the riser and casing (in a multi-cased monitoring
into place and to prevent bridging or break bridges that form in
well), to prevent movement of groundwater or surface water
the annular space.
within the annular space.
3.1.27 target monitoring zone, n—in geoenvironmental
3.3.3 multi-cased well, n—a well constructed by using
programs, the groundwater flow path from a particular area or
successively smaller diameter casings with depth.
facility in which monitoring wells will be screened. The target
3.3.4 packer (monitoring wells)—a transient or dedicated
monitoring zone should be an interval in subsurface materials
device placed in a well that isolates or seals a portion of the
in which there is a reasonable expectation that a monitoring
well, annulus, or borehole at a specific level.
well will intercept groundwater moving beneath an area or
3.3.5 single-cased well, n—a monitoring well constructed
facility and any migrating contaminants that may be present.
with a riser but without an exterior casing.
3.1.28 tremie pipe, n—in wells, a small-diameter pipe or
3.3.6 slot, n—wells screen opening, slot openings have been
tube that is used to transport filter pack materials and annular
designated by numbers which correspond to the width of the
seal materials from the ground surface into an annular space.
openings in thousandths of an inch. A No. 10 slot screen, for
3.1.29 uniformity coeffıcient, n—in soils, the ratio of D /
example, is an opening of 0.010 inch [0.25 mm].
D ,whereD andD areparticlediameterscorrespondingto
10 60 10
60 % and 10 % finer on the cumulative particle size curve,
4. Significance and Use
respectively.
4.1 This practice for the design and installation of ground-
3.1.30 uniformly graded, n—in soils, a quantitative defini-
water monitoring wells will promote (1) efficient and effective
tion of the particle size distribution of a soil that consists of a
site hydrogeological characterization; (2) durable and reliable
majorityofparticlesbeingofapproximatelythesamediameter.
wellconstruction;and (3)acquisitionofrepresentativeground-
A granular material is considered uniformly graded when the
water quality samples, groundwater levels, and hydraulic
uniformity coefficient is less than about five (Test Method
conductivity testing data from monitoring wells. The practices
D2487). Comparable to the geologic term well sorted.
established herein are affected by governmental regulations
and by site-specific geological, hydrogeological,
3.1.31 vented cap, n—in wells/piezometers, a cap with a
climatological, topographical, and subsurface geochemical
small hole that is installed on top of the riser.
conditions. To meet these geoenvironmental challenges, this
3.1.32 weep hole, n—in drilling, a small-diameter hole
practice promotes the development of a conceptual hydrogeo-
(usually ⁄4 in.) drilled into the protective casing above the
logic model prior to monitoring well design and installation.
ground surface that serves to drain out water that may enter the
annulus between the riser and the protective casing. NOTE 1—This practice presents a design for monitoring wells that will
D5092/D5092M − 16
be effective in the majority of formations. This practice is in general
5.2.1 Literature Search—Every effort should be made to
accordance with other national and state guidance documents on well
collect and review all applicable field and laboratory data from
construction (ANSI/NGWA-01-14 (1) and California EPA (2)) however;
previous explorations of the project area. Information such as,
national, state, or local design regulations may control design and
butnotlimitedto,topographicmaps,aerialimagery(seeGuide
installation.
D5518), site ownership and utilization records, geologic and
4.2 Aproperly designed and installed groundwater monitor-
hydrogeologic maps and reports, mineral resource surveys,
ing well provides essential information on one or more of the
water well logs, information from local well drillers, agricul-
following subjects:
tural soil reports, geotechnical engineering reports, and other
4.2.1 Formation geologic and hydraulic properties;
engineering maps and reports related to the project area should
4.2.2 Potentiometric surface of a particular hydrologic
be reviewed to locate relevant site information.
unit(s);
5.2.2 Field Reconnaissance—Early in the exploration, the
4.2.3 Water quality with respect to various indicator param-
soil and rocks in open cut areas (for example, roadcuts,
eters; and
streamcuts) in the vicinity of the project should be studied, and
4.2.4 Waterchemistrywithrespecttoacontaminantrelease.
various soil and rock profiles noted. Special consideration
NOTE 2—The quality of the result produced by this standard is
should be given to soil color and textural changes, landslides,
dependent on the competence of the personnel performing it, and the
seeps, and springs within or near the project area.
suitability of the equipment and facilities used. Agencies that meet the
5.2.3 Preliminary Conceptual Model—The distribution of
criteria of Practice D3740 are generally considered capable of competent
and objective testing/sampling/inspection/etc. Users of this standard are the predominant soil and rock units likely to be found during
cautioned that compliance with Practice D3740 does not in itself assure
subsurface exploration may be hypothesized at this time in a
reliable results. Reliable results depend on many factors; Practice D3740
preliminary conceptual site model using information obtained
provides a means of evaluating some of those factors.
in the literature search and field reconnaissance. In areas where
Practice D3740 was developed for agencies engaged in the laboratory
the geology is relatively uniform, well documented in the
testing and/or inspection of soils and rock. As such, it is not totally
applicable to agencies performing this practice. However, user of this literature,andsubstantiatedbythefieldreconnaissance,further
practice should recognize that the framework of Practice D3740 is
refinement of the conceptual model may not be necessary
appropriate for evaluating the quality of an agency performing this
unless anomalies are discovered in the well drilling stage.
practice. Currently there is no known qualifying national authority that
inspects agencies that perform this practice. Use of certified water well
5.3 Field Exploration—The goal of the field exploration is
drillers are recommended. There are national and state agencies that
to refine the preliminary conceptual site model so that the
certify water well drillers.
target monitoring zone(s) is (are) identified prior to monitoring
well installation.
5. Site Characterization
5.3.1 Exploratory Boreholes and Direct-Push Methods—
5.1 General—A thorough knowledge of site-specific
Characterization of the flow paths conceptualized in the initial
geologic, hydrologic and geochemical conditions is necessary
reconnaissance involves defining the porosity (type and
to properly apply the monitoring well design and installation
amount), hydraulic conductivity, stratigraphy, lithology, grada-
procedures contained within this practice. Development of a
tion and structure of each hydrologic unit encountered beneath
conceptual site model, that identifies the target monitoring
the site. These characteristics are defined by conducting an
zone(s), and generates a three dimensional (3-D) picture of
exploratory program which may include, but not limited to:
contaminant distribution and contaminant movement
drilled boreholes (see Guide D6286 for selection of drilling
pathways,isrecommendedpriortomonitoringwelldesignand
methods) and direct-push methods (for example, cone pen-
installation. Development of the conceptual site model is
etrometers (see Test Method D5778 or Guide D6067)or
accomplished in two phases—an initial reconnaissance, after
direct-push machines using soil sampling, groundwater sam-
which a preliminary conceptual model is created, and a field
pling and/or electrical conductivity measurement tools (see
exploration, after which a revised conceptual model is formu-
Guides D6001 and D6282; Practices D7242 and D8037).
lated. When the hydrogeology of a project area is relatively
Exploratory boreholes and direct-push holes should be deep
uncomplicatedandwelldocumentedintheliterature,theinitial
enough to develop the required engineering and hydrogeologic
reconnaissance may provide sufficient information to identify
data for determining the preferential flow pathway(s), target
flow paths and the target monitoring zone(s). However, where
monitoring zone(s), or both.
limited or no background data are available or where the
5.3.1.1 Sampling—Soil and rock properties should not be
geology is complex, a field exploration will be required to
predicted wholly on field description or classification, but
develop the necessary conceptual site model.
should be confirmed by laboratory and/or field tests made on
5.2 Initial Reconnaissance of Project Area—The goal of the
samples or in boreholes or wells. Representative soil or rock
initial reconnaissance of the project area is to identify and
samples of each material that is significant to the design of the
locate those zones or preferential flow pathways with the
monitoring well system should be obtained and evaluated by a
greatest potential to transmit fluids from the project area.
geologist, hydrogeologist, soil scientist or engineer trained and
Identifying these flow pathways is the first step in selecting the
experienced in soil and rock analysis. Soil sample collection
target groundwater monitoring zone(s).
shouldbeconductedaccordingtoPracticeD1452,TestMethod
D1586, Practice D3550, Guide D6282, Practice D6519 or
Practice D1587, whichever is appropriate given the anticipated
The boldface numbers in parentheses refer to a list of references at the end of
this standard. characteristics of the soil samples (see Guide D6169 for
D5092/D5092M − 16
selection of soil sampling methods). Rock samples should be are indicated. Borehole methods such as resistivity, gamma,
collected according to Practice D2113. Soil samples obtained gamma-gamma, neutron, and caliper logs (see Guide D6167)
for evaluation of hydraulic properties should be containerized can be useful to confirm specific subsurface geologic condi-
and identified for shipment to a laboratory. Special measures to tions. Gamma logs (Guide D6274) are particularly useful in
preserve either the continuity of the sample or the natural existing cased wells.
moisture are not usually required. However, soil and rock 5.3.3 Groundwater Flow Direction—Groundwater flow di-
samples obtained for evaluation of chemical properties often rection is generally determined by measuring the vertical and
require special field preparation and preservation to prevent horizontal hydraulic gradient within each conceptualized flow
significant alteration of the chemical constituents during trans- pathway.However,becausewaterwillflowalongthepathways
portation to a laboratory (see Practice D6640). Rock samples of least resistance in the highest hydraulic conductivity, most
for evaluation of hydraulic properties are usually obtained transmissive, formation materials at the site, actual flow
using a split-inner-tube core barrel. Evaluation and logging of direction may be oblique to the average hydraulic gradient
the core samples is usually done in the field before the core is (withinburiedstreamchannelsorglacialvalleys,forexample).
removed from the core barrel. Flow direction is determined by first installing piezometers in
the exploratory boreholes that penetrate the zone(s) of interest
5.3.1.2 Boring Logs—Care should be taken to prepare and
at the site. The depth and location of the piezometers will
retain a complete boring log and sampling record for each
depend upon anticipated hydraulic connections between con-
exploratory boring or direct-push hole (see Guide D5434).
ceptualized flow pathways and their respective lateral direction
NOTE3—Siteexplorationsconductedforthepurposeofgeneratingdata
of flow. Following careful evaluation, it may be possible to
for the installation of groundwater monitoring wells can vary greatly due
utilize existing private or public wells to obtain water-level
to the availability of reliable site data or the lack thereof. The general
data (Guide D6285). The construction integrity of such wells
procedure would be as follows: (1) gather factual data regarding the
surficial and subsurface conditions, (2) analyze the data, (3) develop a should be verified to ensure that the water levels obtained from
conceptual model of the site conditions, (4) locate the monitoring wells
the wells are representative only of the zone(s) of interest.
based on the first three steps. Monitoring wells should only be installed
Following water-level data acquisition, a potentiometric sur-
with sufficient understanding of the geologic, and hydrologic and geo-
face map should be prepared. Flow pathways are ordinarily
chemical conditions present at the site. Monitoring wells often serve as
determined to be at right angles, or nearly so, to the equipo-
part of an overall site exploration for a specific purpose, such as
determining the extent of contamination present, or for predicting the
tential lines, though consideration of complex geology can
effectiveness of aquifer remediation. In these cases, extensive additional
result in more complex interpretations of flow
geotechnical and hydrogeologic information may be required that would
go beyond the Section 5, Site Characterization, description. 5.4 Completing the Conceptual Model—Aseriesofgeologic
andhydrogeologiccrosssectionsshouldbedevelopedtorefine
Boring logs should include the location, geotechnical data
the conceptual model. This is accomplished by first plotting
(that is, penetration rates or blow counts and sample intervals),
logs of soil and rock observed in the exploratory soil boreholes
and sample description information for each material identified
or test pits, and interpreting between these logs using the
in the borehole either by symbol or word description, or both.
geologic and engineering interrelationships between other soil
Description and identification of soils should be in accordance
and rock data observed in the initial reconnaissance or with
with Practice D2488; classification of soils should be in
geophysical techniques. Extrapolation of data into adjacent
accordance with either Practice D2487 or Practice D3282.
areas should be done only where geologically uniform subsur-
Identification of rock material should be based on Nomencla-
face conditions are known to exist.The next step is to integrate
ture C294 or by an appropriate geologic classification system.
the geologic profile data with the potentiometric data for both
Observations of seepage, free water, and water levels should
vertical and horizontal hydraulic gradients. Plan view and
also be noted. The boring logs should be accompanied by a
cross-sectional flow nets should be constructed. Following the
report that includes a description of the area investigated; a
analysis of these data, conclusions can be made as to which
map illustrating the vertical and horizontal location (with
flow pathway(s) is (are) the appropriate target monitoring
reference to national vertical datum such as North American
zone(s).
VerticalDatumof1988[NAVD88]ortoastandardizedsurvey
grid)ofeachexploratoryboreholeortestpit,orboth;andcolor
6. Monitoring Well Construction Materials
photographs of rock cores, soil samples, and exposed strata
6.1 General—Thematerialsthatareusedintheconstruction
labeled with a date and identification.
of a monitoring well that come in contact with water samples
5.3.2 Geophysical Exploration—Geophysical surveys may
should not alter the chemical quality of the sample for the
be used to supplement borehole and outcrop observation data
constituents being examined. The riser, well screen, and
and to aid in interpretation between borings. Appropriate
annular seal installation equipment should be cleaned imme-
surface and borehole geophysical methods for meeting site-
diately prior to well installation (see either Practice D5088 or
specificprojectobjectivescanbeselectedbyconsultingGuides
D5608) or certified clean from the manufacturer and delivered
D6429 and D5753 respectively. Surface geophysical methods
to the site in a protective wrapping.
such as seismic (Guide D5777), electrical-resistivity (Guide
D6431), ground-penetrating radar (Guide D6432), gravity 6.2 Water—Water used in the drilling process, to prepare
(Guide D6430) and electromagnetic conductance surveys grout mixtures and to decontaminate the well screen, riser, and
(Guide D6639) can be particularly valuable when distinct annular sealant injection equipment, should be obtained from a
differencesinthepropertiesofcontiguoussubsurfacematerials source of known chemistry that does not contain constituents
D5092/D5092M − 16
that could compromise the integrity of the well installation. 6.3.2 Materials—The primary filter pack should consist of
Water used in the process should be analyzed for the same an inert granular material (generally ranging from gravel to
analytes if required in the sampling plan. very fine sand, depending on formation grain size distribution)
of selected grain size and gradation that is installed in the
6.3 Primary Filter Pack:
annulusbetweenthewellscreenandtheboreholewall.Washed
6.3.1 General—The purposes of the primary filter pack are
and screened silica sands and gravels, with less than 5 %
to act as a filter that retains formation material while allowing
non-siliceous materials, should be specified.
groundwater to enter the well, and to stabilize the formation to
6.3.3 Design—The design theory of filter pack gradation is
keep it from collapsing on the well. The design of the primary
based on mechanical retention of formation materials.
filter pack is based on the grain-size distribution of the
formation material (as determined by sieve analysis—see Test 6.3.3.1 Coarse Grained Formations—For formation mate-
Method D422) to be retained (3, 4, 5, and 6). The grain size rials that are relatively coarse-grained (that is, fine, medium
distribution of the primary filter pack must be fine enough to and coarse sands and gravels), the grain size distribution of the
retain the formation, but coarse enough to allow for unre- primary filter pack is determined by calculating the D (30 %
finer) size, the D (60 % finer) size, and the D (10 % finer)
stricted movement of groundwater into and through the moni-
60 10
toringwell.Thedesignofthewellscreen(see6.4.3andFig.1) size of the filter pack. The first point on the filter pack
mustbedoneinconcertwiththedesignofthefilterpack.After grain-size distribution curve is the D size. The primary filter
development, a monitoring well with a correctly designed and pack is usually selected to have a D grain size that is about
installed filter pack and screen combination should produce 4 to 6 times greater than the D grain size of the formation
samples free of artifactual turbidity. material being retained (see Fig. 1). A multiplication factor of
FIG. 1 Example Grading Curves for Design of Filter Pack and Slot Size (5)
D5092/D5092M − 16
4 is used if the formation material is relatively fine-grained and smallest commercially available slotted well casing is 6 slot,
well sorted or uniform (small range in grain sizes); a multipli- 0.006 in. [0.15 mm]; the smallest commercially available
cation factor of 6 is used if the formation is relatively coarse continuous-slot wire-wound screen is 4 slot, 0.004 in. [0.10
grained and poorly sorted or non-uniform (large range in grain mm]). Second, the finest filter pack material practical for
conventional (tremie tube) installation is a #40 by #70 sieve
sizes). Thus, 70 % of the filter pack will have a grain size that
is 4 to 6 times larger than the D size of the formation size, [425 to 212 µm] sand, which can be used with a well
materials. This ensures that the filter pack is coarser (with a screen slot as small as 8 slot, 0.008-in., [0.20 mm]. Finer
higherhydraulicconductivity)thantheformationmaterial,and grained filter pack materials cannot be placed practically by
allows for unrestricted groundwater flow from the formation either tremie tubes or pouring down the annular space or down
into the monitoring well. augers.
(1) The next 2 points on the filter pack grain-size distribu- (1) Pre-Packed Well Screen—The best method for ensuring
tion curve are the D and D grain sizes.These are chosen so proper installation of filter packs in predominantly fine-grained
60 10
that the ratio between the two grain sizes (the uniformity formation materials is to use pre-packed or sleeved screens,
coefficient) is less than 2.5.This ensures that the filter pack has whicharedescribedindetailinPracticeD6725.A#50by#100
a small range in grain sizes and is uniform (see technical Note [300 to 150 µm] sieve size filter-pack sand can be used with a
4).The D and D grain sizes of the filter pack are calculated 6 slot size pre-packed or sleeved screen, and a #60 by #120
60 10
by a trial and error method using grain sizes that are close to [250 to 125 µm] filter-pack sand can be used with a 4-slot slot
the D size of the filter pack.After the D ,D and D sizes size pre-packed or sleeved screen. Filter packs that are finer
30 30 60 10
of the filter pack are determined, a smooth curve is drawn than these (for example, sands as fine as #100 by #120 [150 to
through these points. The final step in filter pack design is to 125 µm], or silica flour as fine as #200 mesh [75 µm]) can only
specify the limits of the grain size envelope, which defines the be installed within stainless steel mesh sleeves that can be
permissible range in grain sizes for the filter pack. The placed over pipe-based screens. While these sleeves, or the
permissible range on either side of the grain size curve is 8 %. space between internal and external screens in a pre-packed
well screen may be as thin as ⁄2-in. [15 mm], the basis for
The boundaries of the grain size envelope are drawn on either
side of the filter pack grain-size distribution curve, and filter mechanical retention dictates that a filter-pack thickness of
only two or three grain diameters is needed to contain and
packdesigniscomplete.Forexamples,seereferences(3, 4, 5).
A filter medium having a grain-size distribution as close as control formation materials. Laboratory tests have demon-
possible to this curve is then obtained from a local sand strated that a properly sized filter pack material with a
supplier. thickness of less than ⁄2-in. [15 mm] successfully retains
formation particles regardless of the velocity of water passing
NOTE4—Becausethewellscreenslotshaveuniformopenings,thefilter
through the filter pack. (3, 4)
pack should be composed of particles that are as uniform in size as is
(2) The theoretical limit of mechanical filtration for moni-
practical. Ideally, the uniformity coefficient (the quotient of the 60 %
toring wells is defined by the finest filter pack material that can
passing, D size divided by the 10 % passing D size [effective size]) of
60 10
the filter pack should be 1.0 (that is, the D % and the D % sizes should
be practically installed via a pre-packed or sleeved screen
60 10
be identical). However, a more practical and consistently achievable
encased within a very fine mesh screen of stainless steel or
uniformity coefficient for all ranges of filter pack sizes is 2.5. This value
other suitable material. Dam filter design practice has found
of 2.5 should represent a maximum value, not an ideal.
that a medium sand filter with sufficient fine fraction (10 to
6.3.3.2 Fine-Grained Formations—In formation materials
30 %) of #50 to #100 sand with a D less than 0.2 mm is
that are predominantly fine-grained (finer than fine to very fine
effective in retaining most all clay formation materials (8, 9).
sands), soil piping can occur when a hydraulic gradient exists
NOTE 5—Although not recommended as standard practice, often a
between the formation and the well (as would be the case
project requires drilling and installing the well in one phase of work.
Therefore, the filter pack materials must be ordered and delivered to the
during well development and sampling).To prevent soil piping
drillsitebeforesoilsamplescanbecollected.Inthesecases,thesuggested
in these materials, the following criteria are used for designing
wellscreenslotsizeandfilterpackmaterialcombinationsarepresentedin
granular filter packs (7):
Table 1.
D of filter D of filter
15 15
6.4 Well Screen:
# 4 to 5 and $4to5
D of formation D of formation
85 15
6.4.1 General—Purposes of the well screen are to provide
The left half of this equation is the fundamental criterion for designed openings for groundwater flow through the well, and
the prevention of soil piping through a granular filter, while the to prevent migration of filter pack and formation material into
right half of the equation is the hydraulic conductivity crite- the well. Well screen design is based on either t
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
´1
Designation: D5092 − 04 (Reapproved 2010) D5092/D5092M − 16
Standard Practice for
Design and Installation of Groundwater Monitoring Wells
This standard is issued under the fixed designation D5092;D5092/D5092M; the number immediately following the designation indicates
the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last
reapproval. A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
ε NOTE—The units statement in 1.5 was revised editorially in August 2010.
1. Scope Scope*
1.1 This practice describes a methodology for designing and installing conventional (screened and filter-packed) groundwater
monitoring wells suitable for formations ranging from unconsolidated aquifers (i.e., (that is, sands and gravels) to granular
materials having grain-size distributions with up to 50 % passing a #200 sieve and as much as 20 % clay-sized material (i.e., (that
is, silty fine sands with some clay). Formations finer than this (i.e., (that is, silts, clays, silty clays, clayey silts) should not be
monitored using conventional monitoring wells, as representative groundwater samples, free of artifactual turbidity, cannot be
assured using currently available technology. Alternative monitoring technologies (not described in this practice) should be used
in these formationscan be monitored but the well may not yield sufficient water required for sampling, and fine filter pack and
screen requirements are difficult and costly to install. Use of coarser filter/screens in fine formations will result in wells with
unstable filter packs and associated elevated sample turbidity that may adversely affect sample accuracy and data quality
objectives. This practice is not applicable in fractured or karst rock conditions, but may be applicable for other porous rock
formations.
1.2 The recommended monitoring well design and installation procedures presented in this practice are based on the assumption
that the objectives of the program are to obtain representative groundwater samples and other representative groundwater data from
a targeted zone of interest in the subsurface defined by site characterization.
1.3 This practice, practice when used on coarse grained sand and gravel aquifers, in combination with proper well development
(D5521), proper groundwater sampling procedures (D4448), and proper well maintenance and rehabilitation (D5978), will permit
acquisition of groundwater samples free of artifactual turbidity, eliminate siltation of wells between sampling events, and permit
acquisition of accurate groundwater levels and hydraulic conductivity test data from the zone screened by the well. For wells
installed in fine-grained formation materials (up to 50 % passing a #200 sieve), it is generally necessarymaterials, it is generally
necessary to use much finer pre-packed well screens (6.3.3.2 to use ) and/or employ sampling methods that minimize screen intake
flow velocity, and disturbance of the well column including suspension of settled solids in the well. Using low-flow purging and
sampling techniques (D6771) in combination with proper wellor passive sampling devices (D7929 design to collect turbidity-free
samples. ) are two means to minimize the potential sample bias associated with turbidity.
1.4 This practice applies primarily to well design and installation methods used in drilled boreholes. Other Standards,standards,
including Guide D6724 and Practice D6725, cover installation of monitoring wells using direct-push methods.
1.5 Units—The values stated in either inch-pound units or SI units [presented in brackets] are to be regarded as standard, except
as noted below. The values separately as standard. The values stated in each system may not be exact equivalents; therefore, each
system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the
standard. Equivalent values given in parentheses are mathematical conversions to SI units, which are provided for information only
and are not considered standard.shown for mix designs and sieves sizes.
1.5.1 Sieve Designations (Specification E11) are identified using the “alternate” system, for example, #40, #200 sieve etc. with
nominal opening size in inches and particle sizes in mm. See Specification E11 for standard metric sieve sizes.
1.5.2 The gravitational system of inch-pound units is used when dealing with inch-pound units. In this system, the pound (lbf)
represents a unit of force (weight), while the unit forWell screen slots are expressed in inches and the metric equivalent is given
in the terminology section and when necessary in the standard (see 3.3.6mass is slugs.).
This practice is under the jurisdiction of ASTM Committee D18 on Soil and Rock and is the direct responsibility of Subcommittee D18.21 on Groundwater and Vadose
Zone Investigations.
Current edition approved Aug. 1, 2010Nov. 15, 2016. Published September 2010December 2016. Originally approved in 1990. Last previous edition approved in 20042010
ε1ɛ1
as D5092D5092–04(2010)–04 . DOI: 10.1520/D5092-04R10E01.10.1520/D5092_D5092M-16.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5092/D5092M − 16
1.6 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice
D6026, unless superseded by this standard.
1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use.
1.8 This practice offers a set of instructions for performing one or more specific operations. This document cannot replace
education or experience and should be used in conjunction with professional judgment. Nat all aspects of this practice may be
applicable in all circumstances. This ASTM standard is not intended to represent or replace the standard of care by which the
adequacy of a given professional service must be judged, nor should this document be applied without consideration of a project’s
many unique aspects. The word “Standard” in the title of this document means only that the document has been approved through
the ASTM consensus process.
2. Referenced Documents
2.1 ASTM Standards:
C150 Specification for Portland Cement
C294 Descriptive Nomenclature for Constituents of Concrete Aggregates
D421 Practice for Dry Preparation of Soil Samples for Particle-Size Analysis and Determination of Soil Constants (Withdrawn
2016)
D422 Test Method for Particle-Size Analysis of Soils (Withdrawn 2016)
D653 Terminology Relating to Soil, Rock, and Contained Fluids
D1129 Terminology Relating to Water
D1452 Practice for Soil Exploration and Sampling by Auger Borings
D1586 Test Method for Penetration Test (SPT) and Split-Barrel Sampling of Soils
D1587 Practice for Thin-Walled Tube Sampling of Fine-Grained Soils for Geotechnical Purposes
D2113 Practice for Rock Core Drilling and Sampling of Rock for Site Exploration
D2217 Practice for Wet Preparation of Soil Samples for Particle-Size Analysis and Determination of Soil Constants
D2487 Practice for Classification of Soils for Engineering Purposes (Unified Soil Classification System)
D2488 Practice for Description and Identification of Soils (Visual-Manual Procedure)
D3282 Practice for Classification of Soils and Soil-Aggregate Mixtures for Highway Construction Purposes
D3441 Test Method for Mechanical Cone Penetration Testing of Soils
D3550 Practice for Thick Wall, Ring-Lined, Split Barrel, Drive Sampling of Soils (Withdrawn 2016)
D4220D3740 Practices for Preserving and Transporting Soil SamplesPractice for Minimum Requirements for Agencies Engaged
in Testing and/or Inspection of Soil and Rock as Used in Engineering Design and Construction
D4700 Guide for Soil Sampling from the Vadose Zone
D4750D4448 Test Method for Determining Subsurface Liquid Levels in a Borehole or Monitoring Well (Observation
Well)Guide for Sampling Ground-Water Monitoring Wells (Withdrawn 2010)
D5079 Practices for Preserving and Transporting Rock Core Samples
D5088 Practice for Decontamination of Field Equipment Used at Waste Sites
D5254 Practice for Minimum Set of Data Elements to Identify a Ground-Water Site
D5299 Guide for Decommissioning of Groundwater Wells, Vadose Zone Monitoring Devices, Boreholes, and Other Devices for
Environmental Activities
D5434 Guide for Field Logging of Subsurface Explorations of Soil and Rock
D5518 Guide for Acquisition of File Aerial Photography and Imagery for Establishing Historic Site-Use and Surficial Conditions
D5521 Guide for Development of Groundwater Monitoring Wells in Granular Aquifers
D5608 Practices for Decontamination of Sampling and Non Sample Contacting Equipment Used at Low Level Radioactive
Waste Sites
D5730 Guide for Site Characterization for Environmental Purposes With Emphasis on Soil, Rock, the Vadose Zone and
Groundwater (Withdrawn 2013)
D5753 Guide for Planning and Conducting Borehole Geophysical Logging
D5777 Guide for Using the Seismic Refraction Method for Subsurface Investigation
D5778 Test Method for Electronic Friction Cone and Piezocone Penetration Testing of Soils
D5781 Guide for Use of Dual-Wall Reverse-Circulation Drilling for Geoenvironmental Exploration and the Installation of
Subsurface Water-Quality Monitoring Devices
D5782 Guide for Use of Direct Air-Rotary Drilling for Geoenvironmental Exploration and the Installation of Subsurface
Water-Quality Monitoring Devices
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
The last approved version of this historical standard is referenced on www.astm.org.
D5092/D5092M − 16
D5783 Guide for Use of Direct Rotary Drilling with Water-Based Drilling Fluid for Geoenvironmental Exploration and the
Installation of Subsurface Water-Quality Monitoring Devices
D5784 Guide for Use of Hollow-Stem Augers for Geoenvironmental Exploration and the Installation of Subsurface
Water-Quality Monitoring Devices
D5787 Practice for Monitoring Well Protection
D5872 Guide for Use of Casing Advancement Drilling Methods for Geoenvironmental Exploration and Installation of
Subsurface Water-Quality Monitoring Devices
D5875 Guide for Use of Cable-Tool Drilling and Sampling Methods for Geoenvironmental Exploration and Installation of
Subsurface Water-Quality Monitoring Devices
D5876 Guide for Use of Direct Rotary Wireline Casing Advancement Drilling Methods for Geoenvironmental Exploration and
Installation of Subsurface Water-Quality Monitoring Devices
D5978 Guide for Maintenance and Rehabilitation of Groundwater Monitoring Wells
D5979 Guide for Conceptualization and Characterization of Groundwater Systems
D6001 Guide for Direct-Push Groundwater Sampling for Environmental Site Characterization
D6026 Practice for Using Significant Digits in Geotechnical Data
D6067 Practice for Using the Electronic Piezocone Penetrometer Tests for Environmental Site Characterization
D6167 Guide for Conducting Borehole Geophysical Logging: Mechanical Caliper
D6169 Guide for Selection of Soil and Rock Sampling Devices Used With Drill Rigs for Environmental Investigations
D6235 Practice for Expedited Site Characterization of Vadose Zone and Groundwater Contamination at Hazardous Waste
Contaminated Sites
D6274 Guide for Conducting Borehole Geophysical Logging - Gamma
D6282 Guide for Direct Push Soil Sampling for Environmental Site Characterizations
D6285 Guide for Locating Abandoned Wells
D6286 Guide for Selection of Drilling Methods for Environmental Site Characterization
D6429 Guide for Selecting Surface Geophysical Methods
D6430 Guide for Using the Gravity Method for Subsurface Investigation
D6431 Guide for Using the Direct Current Resistivity Method for Subsurface Investigation
D6432 Guide for Using the Surface Ground Penetrating Radar Method for Subsurface Investigation
D6519 Practice for Sampling of Soil Using the Hydraulically Operated Stationary Piston Sampler
D6639 Guide for Using the Frequency Domain Electromagnetic Method for Subsurface Investigations
D6640 Practice for Collection and Handling of Soils Obtained in Core Barrel Samplers for Environmental Investigations
D6724 Guide for Installation of Direct Push Groundwater Monitoring Wells
D6725 Practice for Direct Push Installation of Prepacked Screen Monitoring Wells in Unconsolidated Aquifers
D6771 Practice for Low-Flow Purging and Sampling for Wells and Devices Used for Ground-Water Quality Investigations
(Withdrawn 2011)
D6914 Practice for Sonic Drilling for Site Characterization and the Installation of Subsurface Monitoring Devices
D7242 Practice for Field Pneumatic Slug (Instantaneous Change in Head) Tests to Determine Hydraulic Properties of Aquifers
with Direct Push Groundwater Samplers
D7929 Guide for Selection of Passive Techniques for Sampling Groundwater Monitoring Wells
D8037 Practice for Direct Push Hydraulic Logging Profiling Variations of Permeability Soils
E11 Specification for Woven Wire Test Sieve Cloth and Test Sieves
F480 Specification for Thermoplastic Well Casing Pipe and Couplings Made in Standard Dimension Ratios (SDR), SCH 40 and
SCH 80
3. Terminology
3.1 Definitions:
3.1.1 annular space; annulus—the space between two concentric strings of casing, or between the casing and the borehole wall.
This includes the space(s) between multiple strings of casing in a borehole installed either concentrically or adjacent to one another.
3.1.1 For definitions of common technical terms in this standard, refer Terminology D653.
3.1.2 artifactual turbidity—turbidity, n—in wells, filters, particulate matter that is not naturally mobile in the groundwater
system and that is produced in some way by the groundwater sampling process. May consist of particles introduced to the
subsurface during drilling or well construction, sheared from the target monitoring zone during pumping or bailing the well, or
produced by exposure of groundwater to atmospheric conditions.
3.1.2.1 Discussion—
May consist of particles introduced to the subsurface during drilling or well construction, sheared from the target monitoring zone
during pumping or bailing the well, or produced by exposure of groundwater to atmospheric conditions.
D5092/D5092M − 16
3.1.3 assessment monitoring—an investigative monitoring program that is initiated after the presence of a contaminant in
groundwater has been detected. The objective of this program is to determine the concentration of constituents that have
contaminated the groundwater and to quantify the rate and extent of migration of these constituents.
3.1.3 ballast—ballast, n—in drilling, materials used to provide stability to a buoyant object (such as casing within a water-filled
borehole).
3.1.4 borehole—borehole, n—in drilling, an open or uncased subsurface hole, generally circular in planplain view, created by
drilling.
3.1.5 borehole log—log, n—in drilling, the record of geologic units penetrated, drilling progress, depth, water level, sample
recovery, volumes, and types of materials used, and other significant facts regarding the drilling and/or installation of an
exploratory borehole or well.
3.1.6 bridge—bridge, n—in drilling, an obstruction within the annulus that may prevent circulation or proper placement of
annular fill materials.
3.1.7 casing—casing, n—in drilling, pipe, finished in sections with either threaded connections or beveled edges to be field
welded, which is installed temporarily or permanently either to counteract caving, to advance the borehole, or to isolate the zone
being monitored, or any combination of these.
3.1.8 casing, protective—protective, n—in drilling, a section of larger diameter pipe that is placed over the upper end of a
smaller diameter monitoring well riser or casing to provide structural protection to the well, to prevent damage to the well, and
to restrict unauthorized access into the well.
3.1.9 casing, surface—surface, n—in drilling, pipe used to stabilize a borehole near the surface during the drilling of a borehole
that may be left in place or removed once drilling is completed.
3.1.10 caving; sloughing—sloughing, v—in drilling, the inflow of unconsolidated material into a borehole that occurs when the
borehole walls lose their cohesiveness.
3.1.11 cement—cement, n—in drilling, commonly known as Portland cement. A mixture that consists of calcareous,
argillaceous, or other silica-, alumina-, and iron-oxide-bearing materials that is manufactured and formulated to produce various
types which are defined in Specification C150. Portland cement is considered a hydraulic cement because it must be mixed with
water to form a cement-water paste that has the ability to harden and develop strength even if cured under water.
3.1.12 centralizer—centralizer, n—in drilling, a device that assists in the centering of a casing or riser within a borehole or
another casing.
3.1.13 confining unit—unit, n—in hydrogeology, a body of relatively low hydraulic conductivity formation material
stratigraphically adjacent to one or more aquifers. Synonymous with “aquiclude,”“ aquitard,” and “aquifuge.”
3.1.13.1 Discussion—
Synonymous with or may include formations that are considered to be “aquiclude,” “aquitard,” and “aquifuge.”
3.1.15 detection monitoring—a program of monitoring for the express purpose of determining whether or not there has been a
contaminant release to groundwater.
3.1.16 d-10—the diameter of a soil particle (preferably in mm) at which 10 % by weight (dry) of the particles of a particular
sample are finer. Synonymous with the effective size or effective grain size.
3.1.17 d-60—the diameter of a soil particle (preferably in mm) at which 60 % by weight (dry) of the particles of a particular
sample are finer.
3.1.14 flush joint or flush coupled—coupled, n—in drilling, casing or riser with ends threaded such that a consistent inside and
outside diameter is maintained across the threaded joints or couplings.
3.1.15 gravel pack—pack, n—in wells, filters, common term used to refer to the primary filter pack of a well (see primary filter
pack).
3.1.20 grout (monitoring wells)—a low-permeability material placed in the annulus between the well casing or riser and the
borehole wall (in a single-cased monitoring well), or between the riser and casing (in a multi-cased monitoring well), to prevent
movement of groundwater or surface water within the annular space.
3.1.16 hydrologic unit—unit, n—in geology, hydrogeology, geologic strata that can be distinguished on the basis of capacity to
yield and transmit fluids. Aquifers and confining units are types of hydrologic units. Boundaries of a hydrologic unit may not
necessarily correspond either laterally or vertically to lithostratigraphic formations.
3.1.22 multi-cased well—a well constructed by using successively smaller diameter casings with depth.
3.1.17 neat cement—cement, n—in grouting, a mixture of Portland cement (Specification C150) and water.
D5092/D5092M − 16
3.1.24 packer (monitoring wells)—a transient or dedicated device placed in a well that isolates or seals a portion of the well,
annulus, or borehole at a specific level.
3.1.18 piezometer—piezometer, n—in wells, hydrogeology, a small-diameter well with a very short screen that is used to
measure changes in hydraulic head, usually in response to pumping a nearby well. Synonymous with observation well.
3.1.19 piping, n—the progressive removal of soil particles from a mass by percolating water, leading to the development of
channels.
3.1.20 primary filter pack—pack, n—in wells, a clean silica sand or sand and gravel mixture of selected grain size and gradation
that is installed in the annular space between the borehole wall and the well screen, extending an appropriate distance above the
screen, for the purpose of retaining and stabilizing the particles from the adjacent formation(s). The term is used in place of gravel
pack.
3.1.21 PTFE tape—tape, n—in drilling, joint sealing tape composed of polytetrafluoroethylene.
3.1.22 riser—riser, n—in wells, the pipe or well casing extending from the well screen to just above or below the ground surface.
3.1.23 secondary filter pack—pack, n—in wells, a clean, uniformly graded sand that is placed in the annulus between the
primary filter pack and the overlying seal, or between the seal and overlying grout backfill, or both, to prevent intrusion of the seal
or grout, or both, into the primary filter pack.
3.1.24 sediment sump—sump, n—in wells, a blank extension of pipe or well casing, closed at the bottom, beneath the well screen
used to collect fine-grained material from the filter pack and adjacent formation materials during the process of well development.
Synonymous with rat trap or tail pipe.
3.1.31 single-cased well—a monitoring well constructed with a riser but without an exterior casing.
3.1.25 static water level—level, n—in hydrogeology, the elevation of the top of a column of water in a monitoring well or
piezometer that is not influenced by pumping or conditions related to well installation, or hydraulic testing.
3.1.26 tamper—tamper, n—in piezometers and wells, a heavy cylindrical metal section of tubing that is operated on a wire rope
or cable. It either slips over the riser and fits inside the casing or borehole annulus, or fits between the riser and annulus. It is
generally used to tamp annular sealants or filter pack materials into place and to prevent bridging or break bridges that form in
the annular space.
3.1.27 target monitoring zone—zone, n—in geoenvironmental programs, the groundwater flow path from a particular area or
facility in which monitoring wells will be screened. The target monitoring zone should be an interval in subsurface materials in
which there is a reasonable expectation that a monitoring well will intercept groundwater moving beneath an area or facility and
any migrating contaminants that may be present.
3.1.28 tremie pipe—pipe, n—in wells, a small-diameter pipe or tube that is used to transport filter pack materials and annular
seal materials from the ground surface into an annular space.
3.1.29 uniformity coeffıcient—coeffıcient, n—in soils, the ratio of d-60/d-10,D /D , where d-60D and d-10D are particle
60 10 60 10
diameters corresponding to 60 % and 10 % finer on the cumulative particle size curve, respectively.
3.1.30 uniformly graded—graded, n—in soils, a quantitative definition of the particle size distribution of a soil that consists of
a majority of particles being of approximately the same diameter. A granular material is considered uniformly graded when the
uniformity coefficient is less than about five (Test Method D2487). Comparable to the geologic term well sorted.
3.1.31 vented cap—cap, n—in wells/piezometers, a cap with a small hole that is installed on top of the riser.
3.1.32 weep hole—hole, n—in drilling, a small-diameter hole (usually ⁄4 in.) drilled into the protective casing above the ground
surface that serves to drain out water that may enter the annulus between the riser and the protective casing.
3.1.33 well completion diagram—diagram, n—in wells, a record that illustrates the details of a well installation.
3.1.34 well screen—screen, n—in wells, a device used to retain the primary or natural filter pack; usually a cylindrical pipe with
openings of a uniform width, orientation, and spacing.
3.2 Terms Referenced in D1129, Committee D19 on Water:
3.2.1 turbidity, n—expression of the optical properties of a sample that causes light rays to be scattered and absorbed rather than
transmitted in straight lines through the sample. (Turbidity of water is caused by the presence of suspended and dissolved matter
such as clay, silt, finely divided organic matter, plankton, other microscopic organisms, organic acids, and dyes.)
3.2.1.1 Discussion—
The D19 definition is related to measurement of turbidity. For the purpose of this standard, turbidity is cloudiness or haziness in
a fluid caused by the presence of small suspended solids that are otherwise imperceptible to the naked eye.
3.3 Definitions of Terms Specific to This Standard:
D5092/D5092M − 16
3.3.1 annular space; annulus, n—the space between two concentric strings of casing, or between the casing and the borehole
wall. This includes the space(s) between multiple strings of casing in a borehole installed either concentrically or adjacent to one
another
3.3.2 grout (monitoring wells), n—a low-permeability material placed in the annulus between the well casing or riser and the
borehole wall (in a single-cased monitoring well), or between the riser and casing (in a multi-cased monitoring well), to prevent
movement of groundwater or surface water within the annular space.
3.3.3 multi-cased well, n—a well constructed by using successively smaller diameter casings with depth.
3.3.4 packer (monitoring wells)—a transient or dedicated device placed in a well that isolates or seals a portion of the well,
annulus, or borehole at a specific level.
3.3.5 single-cased well, n—a monitoring well constructed with a riser but without an exterior casing.
3.3.6 slot, n—wells screen opening, slot openings have been designated by numbers which correspond to the width of the
openings in thousandths of an inch. A No. 10 slot screen, for example, is an opening of 0.010 inch [0.25 mm].
4. Significance and Use
4.1 This practice for the design and installation of groundwater monitoring wells will promote (1) efficient and effective site
hydrogeological characterization; (2) durable and reliable well construction; and (3) acquisition of representative groundwater
quality samples, groundwater levels, and hydraulic conductivity testing data from monitoring wells. The practices established
herein are affected by governmental regulations and by site-specific geological, hydrogeological, climatological, topographical,
and subsurface geochemical conditions. To meet these geoenvironmental challenges, this practice promotes the development of a
conceptual hydrogeologic model prior to monitoring well design and installation.
NOTE 1—This practice presents a design for monitoring wells that will be effective in the majority of formations. This practice is in general accordance
with other national and state guidance documents on well construction (ANSI/NGWA-01-14 (1) and California EPA (2)) however; national, state, or local
design regulations may control design and installation.
4.2 A properly designed and installed groundwater monitoring well provides essential information on one or more of the
following subjects:
4.2.1 Formation geologic and hydraulic properties;
4.2.2 Potentiometric surface of a particular hydrologic unit(s);
4.2.3 Water quality with respect to various indicator parameters; and
4.2.4 Water chemistry with respect to a contaminant release.
NOTE 2—The quality of the result produced by this standard is dependent on the competence of the personnel performing it, and the suitability of the
equipment and facilities used. Agencies that meet the criteria of Practice D3740 are generally considered capable of competent and objective
testing/sampling/inspection/etc. Users of this standard are cautioned that compliance with Practice D3740 does not in itself assure reliable results. Reliable
results depend on many factors; Practice D3740 provides a means of evaluating some of those factors.
Practice D3740 was developed for agencies engaged in the laboratory testing and/or inspection of soils and rock. As such, it is not totally applicable
to agencies performing this practice. However, user of this practice should recognize that the framework of Practice D3740 is appropriate for evaluating
the quality of an agency performing this practice. Currently there is no known qualifying national authority that inspects agencies that perform this
practice. Use of certified water well drillers are recommended. There are national and state agencies that certify water well drillers.
5. Site Characterization
5.1 General—A thorough knowledge of site-specific geologic, hydrologic and geochemical conditions is necessary to properly
apply the monitoring well design and installation procedures contained within this practice. Development of a conceptual site
model, that identifies potential flow paths and the target monitoring zone(s), and generates a 3-D three dimensional (3-D) picture
of contaminant distribution and contaminant movement pathways, is recommended prior to monitoring well design and
installation. Development of the conceptual site model is accomplished in two phases -- an phases—an initial reconnaissance, after
which a preliminary conceptual model is created, and a field investigation,exploration, after which a revised conceptual model is
formulated. When the hydrogeology of a project area is relatively uncomplicated and well documented in the literature, the initial
reconnaissance may provide sufficient information to identify flow paths and the target monitoring zone(s). However, where
limited or no background data are available or where the geology is complex, a field investigationexploration will be required to
develop the necessary conceptual site model.
5.2 Initial Reconnaissance of Project Area—The goal of the initial reconnaissance of the project area is to identify and locate
those zones or preferential flow pathways with the greatest potential to transmit fluids from the project area. Identifying these flow
pathways is the first step in selecting the target groundwater monitoring zone(s).
5.2.1 Literature Search—Every effort should be made to collect and review all applicable field and laboratory data from
previous investigationsexplorations of the project area. Information such as, but not limited to, topographic maps, aerial imagery
(1) Driscoll, F.G., 1986, Groundwater and Wells, Johnson Division, St. Paul, MN, pg.443The boldface numbers in parentheses refer to a list of references at the end of
this standard.
D5092/D5092M − 16
(see Guide D5518), site ownership and utilization records, geologic and hydrogeologic maps and reports, mineral resource surveys,
water well logs, information from local well drillers, agricultural soil reports, geotechnical engineering reports, and other
engineering maps and reports related to the project area should be reviewed to locate relevant site information.
5.2.2 Field Reconnaissance—Early in the investigation,exploration, the soil and rocks in open cut areas (e.g., (for example,
roadcuts, streamcuts) in the vicinity of the project should be studied, and various soil and rock profiles noted. Special consideration
should be given to soil color and textural changes, landslides, seeps, and springs within or near the project area.
5.2.3 Preliminary Conceptual Model—The distribution of the predominant soil and rock units likely to be found during
subsurface exploration may be hypothesized at this time in a preliminary conceptual site model using information obtained in the
literature search and field reconnaissance. In areas where the geology is relatively uniform, well documented in the literature, and
substantiated by the field reconnaissance, further refinement of the conceptual model may not be necessary unless anomalies are
discovered in the well drilling stage.
5.3 Field Investigation—Exploration—The goal of the field investigationexploration is to refine the preliminary conceptual site
model so that the target monitoring zone(s) is (are) identified prior to monitoring well installation.
5.3.1 Exploratory BoringsBoreholes and Direct-Push Methods—Characterization of the flow paths conceptualized in the initial
reconnaissance involves defining the porosity (type and amount), hydraulic conductivity, stratigraphy, lithology, gradation and
structure of each hydrologic unit encountered beneath the site. These characteristics are defined by conducting an exploratory
program which may include drilled soil borings include, but not limited to: drilled boreholes (see Guide D6286 for selection of
drilling methods) and direct-push methods (e.g., (for example, cone penetrometers [see(see Test Method D3441D5778 or Guide
D6067]) or direct-push machines using soil sampling, groundwater sampling and/or electrical conductivity measurement tools
[see(see Guides D6282D6001 and D6001D6282]). ; Practices D7242 and D8037). Exploratory soil borings boreholes and
direct-push holes should be deep enough to develop the required engineering and hydrogeologic data for determining the
preferential flow pathway(s), target monitoring zone(s), or both.
5.3.1.1 Sampling—Soil and rock properties should not be predicted wholly on field description or classification, but should be
confirmed by laboratory and/or field tests made on samples or in boreholes or wells. Representative soil or rock samples of each
material that is significant to the design of the monitoring well system should be obtained and evaluated by a geologist,
hydrogeologist, soil scientist or engineer trained and experienced in soil and rock analysis. Soil sample collection should be
conducted according to Practice D1452, Test Method D1586, Practice D3550, Guide D6282, Practice D6519 or Practice D1587,
whichever is appropriate given the anticipated characteristics of the soil samples (see Guide D6169 for selection of soil sampling
methods). Rock samples should be collected according to Practice D2113. Soil samples obtained for evaluation of hydraulic
properties should be containerized and identified for shipment to a laboratory. Special measures to preserve either the continuity
of the sample or the natural moisture are not usually required. However, soil and rock samples obtained for evaluation of chemical
properties often require special field preparation and preservation to prevent significant alteration of the chemical constituents
during transportation to a laboratory (see Practice D6640). Rock samples for evaluation of hydraulic properties are usually obtained
using a split-inner-tube core barrel. Evaluation and logging of the core samples is usually done in the field before the core is
removed from the core barrel.
5.3.1.2 Boring Logs—Care should be taken to prepare and retain a complete boring log and sampling record for each exploratory
soil boring or direct-push hole (see Guide D5434).
NOTE 3—Site investigationsexplorations conducted for the purpose of generating data for the installation of groundwater monitoring wells can vary
greatly due to the availability of reliable site data or the lack thereof. The general procedure would be as follows: (1) gather factual data regarding the
surficial and subsurface conditions, (2) analyze the data, (3) develop a conceptual model of the site conditions, (4) locate the monitoring wells based on
the first three steps. Monitoring wells should only be installed with sufficient understanding of the geologic, and hydrologic and geochemical conditions
present at the site. Monitoring wells often serve as part of an overall site investigationexploration for a specific purpose, such as determining the extent
of contamination present, or for predicting the effectiveness of aquifer remediation. In these cases, extensive additional geotechnical and hydrogeologic
information may be required that would go beyond the Section 55, Site Characterization, description.
Boring logs should include the location, geotechnical data (that is, penetration rates or blow counts),counts and sample
intervals), and sample description information for each material identified in the borehole either by symbol or word description,
or both. Description and identification of soils should be in accordance with Practice D2488; classification of soils should be in
accordance with either Practice D2487 or Practice D3282. Identification of rock material should be based on Nomenclature C294
or by an appropriate geologic classification system. Observations of seepage, free water, and water levels should also be noted.
The boring logs should be accompanied by a report that includes a description of the area investigated; a map illustrating the
vertical and horizontal location (with reference to either national vertical datum such as North American Vertical Datum of 1988
[NAVD 88] or to a standardized survey grid) of each exploratory soil boring borehole or test pit, or both; and color photographs
of rock cores, soil samples, and exposed strata labeled with a date and identification.
5.3.2 Geophysical Exploration—Geophysical surveys may be used to supplement soil boring borehole and outcrop observation
data and to aid in interpretation between soil borings. Appropriate surface and borehole geophysical methods for meeting
site-specific project objectives can be selected by consulting Guides D6429 and D5753 respectively. Surface geophysical methods
such as seismic (Guide D5777), electrical-resistivity (Guide D6431), ground-penetrating radar (Guide D6432), gravity (Guide
D6430) and electromagnetic conductance surveys (Guide D6639) can be particularly valuable when distinct differences in the
D5092/D5092M − 16
properties of contiguous subsurface materials are indicated. Borehole methods such as resistivity, gamma, gamma-gamma, neutron,
and caliper logs (see Guide D6167) can be useful to confirm specific subsurface geologic conditions. Gamma logs (Guide D6274)
are particularly useful in existing cased wells.
5.3.3 Groundwater Flow Direction—Groundwater flow direction is generally determined by measuring the vertical and
horizontal hydraulic gradient within each conceptualized flow pathway. However, because water will flow along the pathways of
least resistance (withinin the highest hydraulic conductivity conductivity, most transmissive, formation materials at the site),site,
actual flow direction may be oblique to the average hydraulic gradient (within buried stream channels or glacial valleys, for
example). Flow direction is determined by first installing piezometers in the exploratory soil borings boreholes that penetrate the
zone(s) of interest at the site. The depth and location of the piezometers will depend upon anticipated hydraulic connections
between conceptualized flow pathways and their respective lateral direction of flow. Following careful evaluation, it may be
possible to utilize existing private or public wells to obtain water-level data. data (Guide D6285). The construction integrity of such
wells should be verified to ensure that the water levels obtained from the wells are representative only of the zone(s) of interest.
Following water-level data acquisition, a potentiometric surface map should be prepared. Flow pathways are ordinarily determined
to be at right angles, or nearly so, to the equipotential lines, though consideration of complex geology can result in more complex
interpretations of flow
5.4 Completing the Conceptual Model—A series of geologic and hydrogeologic cross sections should be developed to refine the
conceptual model. This is accomplished by first plotting logs of soil and rock observed in the exploratory soil boringsboreholes
or test pits, and interpreting between these logs using the geologic and engineering interrelationships between other soil and rock
data observed in the initial reconnaissance or with geophysical techniques. Extrapolation of data into adjacent areas should be done
only where geologically uniform subsurface conditions are known to exist. The next step is to integrate the geologic profile data
with the potentiometric data for both vertical and horizontal hydraulic gradients. Plan view and cross-sectional flow nets should
be constructed. Following the analysis of these data, conclusions can be made as to which flow pathway(s) is (are) the appropriate
target monitoring zone(s).
NOTE 2—UUse of groundwater monitoring wells is difficult and may not be a reliable technology in fine-grained, low hydraulic conductivity formation
materials with primary porosity because of (1) the disproportionate influence that microstratigraphy has on groundwater flow in fine-grained strata; (2)
the proportionally higher vertical flow component in low hydraulic conductivity strata; and (3) the presence of indigenous metallic and inorganic
constituents in the matrix that make water-quality data evaluation difficult.
6. Monitoring Well Construction Materials
6.1 General—The materials that are used in the construction of a monitoring well that come in contact with water samples
should not alter the chemical quality of the sample for the constituents being examined. The riser, well screen, and annular seal
installation equipment should be cleaned immediately prior to well installation (see either Practice D5088 or D5608) or certified
clean from the manufacturer and delivered to the site in a protective wrapping. Samples of the riser and screen material, cleaning
water, filter pack, annular seal, bentonite, and mixed grout should be retained to serve as quality control until the completion of
at least one round of groundwater quality sampling and analysis has been completed.
6.2 Water—Water used in the drilling process, to prepare grout mixtures and to decontaminate the well screen, riser, and annular
sealant injection equipment, should be obtained from a source of known chemistry that does not contain constituents that could
compromise the integrity of the well installation. Water used in the process should be analyzed for the same analytes if required
in the sampling plan.
6.3 Primary Filter Pack:
6.3.1 General—The purposes of the primary filter pack are to act as a filter that retains formation material while allowing
groundwater to enter the well, and to stabilize the formation to keep it from collapsing on the well. The design of the primary filter
pack is based on the grain-size distribution of the formation material (as determined by sieve analysis—see Test Method D422)
to be retained. retained (3, 4, 5, and 6). The grain size distribution of the primary filter pack must be fine enough to retain the
formation, but coarse enough to allow for unrestricted movement of groundwater into and through the monitoring well. The design
of the well screen (see 6.4.3 and Fig. 1) must be done in concert with the design of the filter pack. After development, a monitoring
well with a correctly designed and installed filter pack and screen combination should produce samples free of artifactual turbidity.
6.3.2 Materials—The primary filter pack should consist of an inert granular material (generally ranging from gravel to very fine
sand, depending on formation grain size distribution) of selected grain size and gradation that is installed in the annulus between
the well screen and the borehole wall. Washed and screened silica sands and gravels, with less than 5 % non-siliceous materials,
should be specified.
6.3.3 Design—The design theory of filter pack gradation is based on mechanical retention of formation materials.
6.3.3.1 Coarse Grained Formations—1 For formation materials that are relatively coarse-grained (i.e., (that is, fine, medium and
coarse sands and gravels), the grain size distribution of the primary filter pack is determined by calculating the d-30D (30 % finer)
size, the d-60D (60 % finer) size, and the d-10D (10 % finer) size of the filter pack. The first point on the filter pack grain-size
60 10
distribution curve is the d-30D size. The primary filter pack is usually selected to have a d-30D grain size that is about 4 to
30 30
6 times greater than the d-30D grain size of the formation material being retained (see Fig. 1). A multiplication factor of 4 is used
if the formation material is relatively fine-grained and well sorted or uniform (small range in grain sizes); a multiplication factor
D5092/D5092M − 16
FIG. 31 Example Grading CurveCurves for Design of Monitoring Well ScreensFilter Pack and Slot Si
...