ASTM D5978-96(2011)e1
(Guide)Standard Guide for Maintenance and Rehabilitation of Groundwater Monitoring Wells
Standard Guide for Maintenance and Rehabilitation of Groundwater Monitoring Wells
SIGNIFICANCE AND USE
4.1 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.
4.2 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.
4.3 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.
4.4 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 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.
1.4 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 2011)
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.
ε NOTE—Editorial changes were made throughout in December 2011.
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 circumstances. This ASTM standard is not intended to repre-
sent or replace the standard of care by which the adequacy of
1.1 This guide covers an approach to selecting and imple-
a given professional service must be judged, nor should this
menting a well maintenance and rehabilitation program for
documentbeappliedwithoutconsiderationofaproject’smany
groundwater monitoring wells. It provides information on
unique aspects. The word “Standard” in the title of this
symptomsofproblemsordeficienciesthatindicatetheneedfor
document means only that the document has been approved
maintenance and rehabilitation. It is limited to monitoring
through the ASTM consensus process.
wells, that are designed and operated to provide access to,
representative water samples from, and information about the
2. Referenced Documents
hydraulicpropertiesofthesaturatedsubsurfacewhileminimiz-
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 D652Method of Test for Measuring Mica Stampings Used
maintenance and rehabilitation treatment methods suitable for in Electronic Devices and Incandescent Lamps (With-
monitoring wells is more restricted than for other types of drawn 1956)
wells. Monitoring wells include their associated pumps and D653Terminology Relating to Soil, Rock, and Contained
surface equipment. Fluids
D1889Test Method for Turbidity of Water (Withdrawn
1.2 This guide is affected by governmental regulations and
2007)
by site specific geological, hydrogeological, geochemical,
D4044Test Method for (Field Procedure) for Instantaneous
climatological, and biological conditions.
Change in Head (Slug) Tests for Determining Hydraulic
1.3 This standard does not purport to address all of the
Properties of Aquifers
safety concerns, if any, associated with its use. It is the
D4412TestMethodsforSulfate-ReducingBacteriainWater
responsibility of the user of this standard to establish appro-
and Water-Formed Deposits
priate safety and health practices and determine the applica-
D4448GuideforSamplingGround-WaterMonitoringWells
bility of regulatory limitations prior to use.
D4750Test Method for Determining Subsurface Liquid
1.4 This guide offers an organized collection of information
Levels in a Borehole or Monitoring Well (Observation
or a series of options and does not recommend a specific
Well) (Withdrawn 2010)
course of action. This document cannot replace education or
D5088Practice for Decontamination of Field Equipment
experienceandshouldbeusedinconjunctionwithprofessional
Used at Waste Sites
judgment.Notallaspectsofthisguidemaybeapplicableinall
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 Dec. 1, 2011. Published December 2012. Originally the ASTM website.
approved in 1996. Last previous edition approved in 2005 as D5978 – 96 (2005). The last approved version of this historical standard is referenced on
DOI: 10.1520/D5978-96R11E01. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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D5978 − 96 (2011)
D5092Practice for Design and Installation of GroundWater 3.2.6 well rehabilitation—for the purposes of this guide,
Monitoring Wells synonymous with well rehabilitative or restorative mainte-
D5254Practice for Minimum Set of Data Elements to nance.
Identify a Ground-Water Site
3.2.7 well rehabilitative or restorative maintenance—any
D5299Guide for Decommissioning of Groundwater Wells,
well maintenance action that is initiated for the purpose of
Vadose Zone Monitoring Devices, Boreholes, and Other
correcting well performance that has moved outside of prees-
Devices for Environmental Activities
tablished ranges.
D5408Guide for Set of Data Elements to Describe a
Groundwater Site; Part One—Additional Identification 4. Significance and Use
Descriptors
4.1 Theprocessofoperatinganyengineeredsystem,suchas
D5409Guide for Set of Data Elements to Describe a
monitoring wells, includes active maintenance to prevent,
Ground-Water Site; Part Two—Physical Descriptors
mitigate, or reverse deterioration. Lack of or improper main-
D5410Guide for Set of Data Elements to Describe a
tenance can lead to well performance deficiencies (physical
Ground-Water Site;Part Three—Usage Descriptors
problems) or sample quality degradation (chemical problems).
D5472Test Method for Determining Specific Capacity and
These problems are intrinsic to monitoring wells, which are
Estimating Transmissivity at the Control Well
often left idle for long periods of time (as long as a year),
D5474GuideforSelectionofDataElementsforGroundwa-
installed in non-aquifer materials, and installed to evaluate
ter Investigations
contamination that can cause locally anomalous hydrogeo-
D5521GuideforDevelopmentofGround-WaterMonitoring
chemical conditions. The typical solutions for these physical
Wells in Granular Aquifers
and chemical problems that would be applied by owners and
2.1.1In addition, ASTM Volume 11.01 on Water (I) and
operators of water supply, dewatering, recharge, and other
Volume 11.02 on Water (II) contain numerous test meth-
wells may not be appropriate for monitoring wells because of
ods and standards that may be of value to the user of this
the need to minimize their impact on the conditions that
guide.
monitoring wells were installed to evaluate.
3. Terminology
4.2 This guide covers actions and procedures, but is not an
encyclopedic guide to well maintenance. Well maintenance
3.1 Definitions:
planning and execution is highly site and well specific.
3.1.1 For definitions of common technical terms in this
standard, refer to Terminology D652 and Guide D5521.
4.3 The design of maintenance and rehabilitation programs
3.2 Definitions of Terms Specific to This Standard:
and the identification of the need for rehabilitation should be
3.2.1 well development—actions taken during the installa-
based on objective observation and testing, and by individuals
tion and start-up of a well for the purpose of mitigating or
knowledgeable and experienced in well maintenance and
correcting damage done to the adjacent geologic formations
rehabilitation.Usersofthisguideareencouragedtoconsultthe
and filter materials that might affect the well’s ability to
references provided.
produce representative samples.
4.4 For additional information see Test Methods D1889,
3.2.2 well maintenance—any action that is taken for the
D4412,D5472,andGuidesD4448,D5409,D5410andD5474.
purpose of maintaining well performance (see Discussion) and
extending the life of the well to provide samples that are
5. Well Performance Deficiencies
representative of the groundwater surrounding it. Maintenance
5.1 Proper well design, installation, and development can
includes both physical actions taken at the well and the
minimize well performance deficiencies that result in the need
documentation of those actions and all operating data in order
for maintenance and rehabilitation. Practice D5092 and Guide
to provide benchmarks for comparisons at later times.
D5521 should be consulted. Performance deficiencies include:
3.2.2.1 Discussion—Desired level of well performance can
sand, silt, and clay infiltration; low yield; slow responses to
vary depending on the design objectives.
changes in groundwater elevations; and loss of production.
3.2.3 well preventive maintenance—any well maintenance
5.2 Preventable Causes of Poor Well Performance:
action that is initiated for the purpose of meeting some
5.2.1 Inappropriatewelllocationorscreenedinterval.These
preestablished rule or schedule that applies while well perfor-
maybeunavoidableifarequirementforsitecharacterizationor
mance is still within preestablished ranges.
monitoring exists,
3.2.4 well reconstructive maintenance—any preventive or
5.2.2 Inappropriate drilling technique or methodology for
rehabilitative well maintenance action involving the replace-
materials screened,
ment of a major component (for example, pump, surface
5.2.3 Inadequate intake structure design (screen, filter
protection).
material, and so forth),
3.2.5 well redevelopment—any preventive or rehabilitative 5.2.4 Inappropriate well construction materials. This may
wellmaintenanceaction,takenafterstart-up,forthepurposeof lead to corrosion or collapse,
mitigating or correcting deterioration of the filter pack or 5.2.5 Improper construction, operation, or maintenance, or
adjacent geologic formations, or both, due to the well’s combination thereof, of borehole or well, wellhead protection,
presence and operation over time, usually involving physical well cap, and locking device,
development procedures, applied in reaction to deterioration. 5.2.6 Ineffective development,
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D5978 − 96 (2011)
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
was previously utilized, or pumping at a higher rate than
operations, freeze-thaw, or improper chemical or mechanical
previously used could increase the sand/silt content; likewise,
rehabilitation.
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.
2+ 3+
degrade well performance and sample quality. Any change in
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 Chemical Encrustation—Precipitation of calcium or redox potential and biofouling.
2− 0 2−
magnesium carbonate or sulfate, iron, or sulfide compounds
6.3.3 Sulfur (Changes in Total S /S /SO , Sulfur Miner-
can reduce well yield and specific capacity. als and Complexes)—Causes include changes in redox poten-
6.2.2 Biofouling (B
...
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