ASTM D5978-96(2005)
(Guide)Standard Guide for Maintenance and Rehabilitation of Groundwater Monitoring Wells
Standard Guide for Maintenance and Rehabilitation of Groundwater Monitoring Wells
SIGNIFICANCE AND USE
The process of operating any engineered system, such as monitoring wells, includes active maintenance to prevent, mitigate, or reverse deterioration. Lack of or improper maintenance can lead to well performance deficiencies (physical problems) or sample quality degradation (chemical problems). These problems are intrinsic to monitoring wells, which are often left idle for long periods of time (as long as a year), installed in non-aquifer materials, and installed to evaluate contamination that can cause locally anomalous hydrogeochemical conditions. The typical solutions for these physical and chemical problems that would be applied by owners and operators of water supply, dewatering, recharge, and other wells may not be appropriate for monitoring wells because of the need to minimize their impact on the conditions that monitoring wells were installed to evaluate.
This guide covers actions and procedures, but is not an encyclopedic guide to well maintenance. Well maintenance planning and execution is highly site and well specific.
The design of maintenance and rehabilitation programs and the identification of the need for rehabilitation should be based on objective observation and testing, and by individuals knowledgeable and experienced in well maintenance and rehabilitation. Users of this guide are encouraged to consult the references provided.
For additional information see Test Methods D1889, D4412, D5472, and Guides D4448, D5409, D5410 and D5474.
SCOPE
1.1 This guide covers an approach to selecting and implementing a well maintenance and rehabilitation program for groundwater monitoring wells. It provides information on symptoms of problems or deficiencies that indicate the need for maintenance and rehabilitation. It is limited to monitoring wells, that are designed and operated to provide access to, representative water samples from, and information about the hydraulic properties of the saturated subsurface while minimizing impact on the monitored zone. Some methods described herein may apply to other types of wells although the range of maintenance and rehabilitation treatment methods suitable for monitoring wells is more restricted than for other types of wells. Monitoring wells include their associated pumps and surface equipment.
1.2 This guide is affected by governmental regulations and by site specific geological, hydrogeological, geochemical, climatological, and biological conditions.
1.3 The values stated in SI units are to be regarded as the standard.
1.4 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.
1.5 This guide offers an organized collection of information or a series of options and does not recommend a specific course of action. This document cannot replace education or experience and should be used in conjunction with professional judgment. Not all aspects of this guide 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.
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Designation: D5978 − 96(Reapproved 2005)
Standard Guide for
Maintenance and Rehabilitation of Groundwater Monitoring
Wells
This standard is issued under the fixed designation D5978; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
This guide for maintenance and rehabilitation promotes procedures appropriate to groundwater
monitoringwellsinstalledtoevaluatetheextentandnatureofcontamination,progressofremediation,
and for long-term monitoring of either water quality or water level.
1. Scope judgment.Notallaspectsofthisguidemaybeapplicableinall
circumstances. This ASTM standard is not intended to repre-
1.1 This guide covers an approach to selecting and imple-
sent or replace the standard of care by which the adequacy of
menting a well maintenance and rehabilitation program for
a given professional service must be judged, nor should this
groundwater monitoring wells. It provides information on
documentbeappliedwithoutconsiderationofaproject’smany
symptomsofproblemsordeficienciesthatindicatetheneedfor
unique aspects. The word “Standard” in the title of this
maintenance and rehabilitation. It is limited to monitoring
document means only that the document has been approved
wells, that are designed and operated to provide access to,
through the ASTM consensus process.
representative water samples from, and information about the
hydraulicpropertiesofthesaturatedsubsurfacewhileminimiz-
2. Referenced Documents
ing impact on the monitored zone. Some methods described
2.1 ASTM Standards:
herein may apply to other types of wells although the range of
D653Terminology Relating to Soil, Rock, and Contained
maintenance and rehabilitation treatment methods suitable for
Fluids
monitoring wells is more restricted than for other types of
D1889Test Method for Turbidity of Water (Withdrawn
wells. Monitoring wells include their associated pumps and
2007)
surface equipment.
D4044Test Method for (Field Procedure) for Instantaneous
1.2 This guide is affected by governmental regulations and
Change in Head (Slug) Tests for Determining Hydraulic
by site specific geological, hydrogeological, geochemical,
Properties of Aquifers
climatological, and biological conditions.
D4412TestMethodsforSulfate-ReducingBacteriainWater
1.3 The values stated in SI units are to be regarded as the
and Water-Formed Deposits
standard.
D4448GuideforSamplingGround-WaterMonitoringWells
D4750Test Method for Determining Subsurface Liquid
1.4 This standard does not purport to address all of the
Levels in a Borehole or Monitoring Well (Observation
safety concerns, if any, associated with its use. It is the
Well) (Withdrawn 2010)
responsibility of the user of this standard to establish appro-
D5088Practice for Decontamination of Field Equipment
priate safety and health practices and determine the applica-
Used at Waste Sites
bility of regulatory limitations prior to use.
D5092Practice for Design and Installation of GroundWater
1.5 This guide offers an organized collection of information
Monitoring Wells
or a series of options and does not recommend a specific
D5254Practice for Minimum Set of Data Elements to
course of action. This document cannot replace education or
Identify a Ground-Water Site
experienceandshouldbeusedinconjunctionwithprofessional
1 2
ThisguideisunderthejurisdictionofASTMCommitteeD18onSoilandRock For referenced ASTM standards, visit the ASTM website, www.astm.org, or
and is the direct responsibility of Subcommittee D18.21 on Groundwater and contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Vadose Zone Investigations. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved Jan. 1, 2005. Published February 2005. Originally the ASTM website.
approved in 1996. Last previous edition approved in 1996 as D5978–96. DOI: The last approved version of this historical standard is referenced on
10.1520/D5978-96R05. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5978 − 96 (2005)
D5299Guide for Decommissioning of Groundwater Wells, adjacent geologic formations, or both, due to the well’s
Vadose Zone Monitoring Devices, Boreholes, and Other presence and operation over time, usually involving physical
Devices for Environmental Activities development procedures, applied in reaction to deterioration.
D5408Guide for Set of Data Elements to Describe a
3.2.6 well rehabilitation—for the purposes of this guide,
Groundwater Site; Part One—Additional Identification
synonymous with well rehabilitative or restorative mainte-
Descriptors
nance.
D5409Guide for Set of Data Elements to Describe a
3.2.7 well rehabilitative or restorative maintenance—any
Ground-Water Site; Part Two—Physical Descriptors
well maintenance action that is initiated for the purpose of
D5410Guide for Set of Data Elements to Describe a
correcting well performance that has moved outside of prees-
Ground-Water Site;Part Three—Usage Descriptors
tablished ranges.
D5472Test Method for Determining Specific Capacity and
Estimating Transmissivity at the Control Well
4. Significance and Use
D5474GuideforSelectionofDataElementsforGroundwa-
4.1 Theprocessofoperatinganyengineeredsystem,suchas
ter Investigations
monitoring wells, includes active maintenance to prevent,
D5521GuideforDevelopmentofGround-WaterMonitoring
Wells in Granular Aquifers mitigate, or reverse deterioration. Lack of or improper main-
tenance can lead to well performance deficiencies (physical
2.1.1In addition, ASTM Volume 11.01 on Water (I) and
Volume 11.02 on Water (II) contain numerous test meth- problems) or sample quality degradation (chemical problems).
These problems are intrinsic to monitoring wells, which are
ods and standards that may be of value to the user of this
guide. often left idle for long periods of time (as long as a year),
installed in non-aquifer materials, and installed to evaluate
contamination that can cause locally anomalous hydrogeo-
3. Terminology
chemical conditions. The typical solutions for these physical
3.1 Definitions:
and chemical problems that would be applied by owners and
3.1.1 Except where noted, all terms and symbols in this
operators of water supply, dewatering, recharge, and other
guideareinaccordancewiththefollowingpublicationsintheir
wells may not be appropriate for monitoring wells because of
order of consideration:
the need to minimize their impact on the conditions that
3.1.1.1 Terminology D653,
monitoring wells were installed to evaluate.
3.1.1.2 Guide D5521,
4.2 This guide covers actions and procedures, but is not an
3.1.1.3 Compilation of ASTM Standard Terminology, 7th
encyclopedic guide to well maintenance. Well maintenance
Edition, 1990, and
planning and execution is highly site and well specific.
3.1.1.4 Webster’s Ninth New Collegiate Dictionary, 1989.
3.2 Definitions of Terms Specific to This Standard:
4.3 The design of maintenance and rehabilitation programs
3.2.1 well development—actions taken during the installa-
and the identification of the need for rehabilitation should be
tion and start-up of a well for the purpose of mitigating or based on objective observation and testing, and by individuals
correcting damage done to the adjacent geologic formations
knowledgeable and experienced in well maintenance and
and filter materials that might affect the well’s ability to rehabilitation.Usersofthisguideareencouragedtoconsultthe
produce representative samples.
references provided.
3.2.2 well maintenance—any action that is taken for the
4.4 For additional information see Test Methods D1889,
purpose of maintaining well performance (see Discussion) and
D4412,D5472,andGuidesD4448,D5409,D5410andD5474.
extending the life of the well to provide samples that are
representative of the groundwater surrounding it. Maintenance
5. Well Performance Deficiencies
includes both physical actions taken at the well and the
5.1 Proper well design, installation, and development can
documentation of those actions and all operating data in order
minimize well performance deficiencies that result in the need
to provide benchmarks for comparisons at later times.
for maintenance and rehabilitation. Practice D5092 and Guide
3.2.2.1 Discussion—Desired level of well performance can
D5521 should be consulted. Performance deficiencies include:
vary depending on the design objectives.
sand, silt, and clay infiltration; low yield; slow responses to
3.2.3 well preventive maintenance—any well maintenance
changes in groundwater elevations; and loss of production.
action that is initiated for the purpose of meeting some
5.2 Preventable Causes of Poor Well Performance:
preestablished rule or schedule that applies while well perfor-
5.2.1 Inappropriatewelllocationorscreenedinterval.These
mance is still within preestablished ranges.
maybeunavoidableifarequirementforsitecharacterizationor
3.2.4 well reconstructive maintenance—any preventive or
monitoring exists,
rehabilitative well maintenance action involving the replace-
5.2.2 Inappropriate drilling technique or methodology for
ment of a major component (for example, pump, surface
materials screened,
protection).
5.2.3 Inadequate intake structure design (screen, filter ma-
3.2.5 well redevelopment—any preventive or rehabilitative terial, and so forth),
wellmaintenanceaction,takenafterstart-up,forthepurposeof 5.2.4 Inappropriate well construction materials. This may
mitigating or correcting deterioration of the filter pack or lead to corrosion or collapse,
D5978 − 96 (2005)
5.2.5 Improper construction, operation, or maintenance, or and low carbon steel) can result from naturally aggressive
combination thereof, of borehole or well, wellhead protection, waters (containing H S, NaCl) or electrolysis.The presence of
well cap, and locking device, contaminants contributes to corrosion through contributions to
5.2.6 Ineffective development, microbial corrosion processes and formation of redox gradi-
5.2.7 Inappropriate pump selection, and ents. Nonaqueous phase solvents may degrade PVC and other
5.2.8 Introduction of foreign substances. plastics. Other environmental conditions such as heat or
radiation may contribute to material deterioration (such as
5.3 Physical Indicators of Well Performance Deficiencies
enhanced embrittlement). Metals such as nickel or chromium
Include:
may be leached from corroding metals. Degradation of plastic
5.3.1 Sand, Silt, and Clay Infiltration—Causes include in-
wellcomponentsmayresultinareleaseofmonomers(suchas
appropriate and inadequate well drilling (for example, auger
vinyl chloride) to the environment (see Note 1).
flight smearing), improper screen and filter pack, improper
casing design or installation, incomplete development, screen
NOTE 1—Naturally aggressive (for metals) waters have been defined as
low pH (<7.0), high DO (>2 mg/L), high H S (>1 mg/L), high dissolved
corrosion, or collapse of filterpack. In rock wells, causes
−
solids (>1000 mg/L), high CO (>50 mg/L), and high Cl content (>500
includethepresenceoffinematerialinfractures.Thepresence
mg/L). However, local conditions may result in corrosion at less extreme
of sand, silt, or clay can result in pump and equipment wear
values. Expression of corrosion is also dependent on materials load.
and plugging, turbid samples, filterpack plugging, or combina-
6.2.4 Change in Turbidity—Causes include biofouling and
tion thereof.
intake structure, screen or filter pack clogging or collapse.
5.3.2 Low Yield—Causes include dewatering, collapse or
Increaseinturbiditymaynotalwaysbetheresultofaproblem
consolidation of fracture or water-bearing zone, pump mal-
withthewell.Changesinthepurgingandsamplingprocedures
function or plugging, screen encrustation or plugging, and
and devices used can affect the turbidity of water from a
pump tubing corrosion or perforation.
monitoring well. For example, using a bailer where a pump
5.3.3 Water Level Decline—Causes include area or regional
was previously utilized, or pumping at a higher rate than
water level decline, well interference, and chemical or micro-
previously used could increase turbidity; likewise, pumping a
bial plugging or encrustation of the borehole, screen, or
well that was previously bailed could increase turbidity.
filterpack.
6.2.5 Change in Sand/Silt Content or Particle Counts—
5.3.4 Loss of Production—Usually caused by pump failure,
Causes include biofouling (resulting in clogging or sloughing)
but can also be caused by dewatering, plugging, or well
and intake structure clogging or collapse. Increase in the
collapse.
sand/silt content may not always be the result of a problem
5.3.4.1 Well Collapse—Canbecausedbytectonism,ground
withthewell.Changesinthepurgingandsamplingprocedures
subsidence, failure of unsupported casing (that is, in caves or
and devices used can affect the sand/silt content of water from
because of faulty grout), corrosion and subsequent failure of
a monitoring well. For example, using a bailer where a pump
screen and casing, improper casing design, local site opera-
was previously utilized, or pumping at a higher rate than
tions, freeze-thaw, or improper chemical or mechanical reha-
previously used could increase the sand/silt content; likewise,
bilitation.
pumping a well that was previously bailed could increase the
5.3.5 Observation of physical damage or other indicator.
sand/silt content.
6. Sample Quality Degradation
6.3 Chemical Indicators (Observed in Groundwater
Samples)—Chemical and biological activity that can lead to
6.1 Alloftheprecedingphysicalwellperformancedeficien-
sample quality degradation include (see Note 2):
cies can result in sample quality degradation by dilution,
cross-contamination, or entrainment of solid material in water
NOTE 2—Changes in chemical indicators can also be a result of
samples. In addition, chemical and biological activity can both
site-wide changes in hydro-geochemistry.
degrade well performance and sample quality. Any change in 2+ 3+
6.3.1 Iron (Changes in Total Fe, Fe /Fe , Iron Minerals
well or aquifer chemistry that results from the presence of the
and Complexes)—Causes include corrosion, changes in redox
well can interfere with accurate characterization of a site.
potential, and biofouling.
2+ 4+
6.2 Physical Indicators—Chemical and biological activity 6.3.2 Manganese (Changes in Total Mn, Mn /Mn , Man-
that can lead to sample quality degradation include: ganese Minerals and Complexes)—Causes include changes in
6.2.1 Chemic
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