ASTM D5978/D5978M-16(2024)

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 D4412, D5472/D5472M, D7726 and Guides D4448, D5254/D5254M, D5521/D5521M, D5409/D5409M, D5410 and D5474.
Note 1: 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...
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 Units—The values stated in either inch-pound units or SI units presented in brackets are to be regarded 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.  
1.4 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice D6026, unless superseded by this standard.  
1.5 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.6 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 ...

General Information

• Status: Published
• Publication Date: 14-Mar-2024
• 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 D5978/D5978M-16 - Standard Guide for Maintenance and Rehabilitation of Groundwater Monitoring Wells
• Effective Date: 15-Mar-2024
• Refers: ASTM D4412-19(2024) - Standard Test Methods for Sulfate-Reducing Bacteria in Water and Water-Formed Deposits
• Effective Date: 01-Apr-2024
• Refers: ASTM D4412-19 - Standard Test Methods for Sulfate-Reducing Bacteria in Water and Water-Formed Deposits
• Effective Date: 01-Dec-2019
• Referred By: ASTM D6771-21 - Standard Practice for Low-Flow Purging and Sampling Used for Groundwater Monitoring
• Effective Date: 15-Mar-2024

Overview

ASTM D5978/D5978M-16(2024), "Standard Guide for Maintenance and Rehabilitation of Groundwater Monitoring Wells," provides a structured approach for selecting and implementing maintenance and rehabilitation programs for groundwater monitoring wells. Developed by ASTM International, this standard addresses the unique requirements of monitoring wells, which are critical for assessing groundwater quality, tracking contamination, and evaluating remediation efforts. The guide emphasizes minimizing impacts to the monitored environment and recognizes that procedures must be adapted to site-specific geological, hydrogeological, and regulatory conditions.

Proper maintenance and rehabilitation are essential for ensuring reliable data collection, extending well service life, and preserving well integrity. Neglect or improper maintenance can decrease well performance and lead to degraded sample quality, undermining the effectiveness of environmental monitoring and site management programs.

Key Topics

• Maintenance Planning and Execution
  The standard outlines the importance of preventative and rehabilitative maintenance based on objective observation, regular testing, and professional judgment. Well maintenance activities should be documented and tailored to the site’s unique characteristics.

• Symptoms and Indicators
  Guidance is given on identifying performance deficiencies, such as:

  • Infiltration of sand, silt, or clay
  • Reduced yield or slow water level response
  • Increased turbidity or changes in chemical indicators (e.g., iron, manganese, sulfur, pH, conductivity)
  • Physical damage or corrosion of well components
  • Biofouling and encrustation

• Maintenance Program Design
  Maintenance programs should include:

  • Routine inspection and monitoring
  • Benchmarking hydraulic performance and water chemistry
  • Decision-making processes for when to initiate rehabilitation or decommissioning

• Rehabilitation Procedures
  Recommendations are provided for when and how to perform well rehabilitation, with emphasis on minimizing impacts to groundwater chemistry. Physical methods are preferred, with chemical methods being used only when absolutely necessary and in compliance with regulatory requirements.

• Data Management and Reporting
  Systematic record keeping is emphasized, including the collection of data on well location, design, operational history, maintenance actions, observations, and testing results.

Applications

This ASTM standard is primarily used by environmental professionals, engineers, hydrogeologists, and site operators responsible for:

• Environmental site assessment and remediation projects
• Regulatory compliance on contaminated land or water supply monitoring
• Ongoing groundwater quality or level monitoring at industrial sites, landfills, or remediation projects
• Long-term stewardship and management of groundwater resources

By following the guidelines in ASTM D5978/D5978M, organizations can ensure reliable groundwater monitoring, satisfy regulatory requirements, and proactively address issues that might compromise well performance or sample integrity. The standard supports effective environmental management and risk mitigation for projects involving groundwater resources.

Related Standards

Several other ASTM standards and guides are referenced for comprehensive groundwater monitoring well management, including:

• ASTM D4448 - Guide for Sampling Ground-Water Monitoring Wells
• ASTM D5092/D5092M - Practice for Design and Installation of Groundwater Monitoring Wells
• ASTM D4412 - Test Methods for Sulfate-Reducing Bacteria in Water and Water-Formed Deposits
• ASTM D4750 - Test Method for Determining Subsurface Liquid Levels in a Borehole or Monitoring Well
• ASTM D5410 - Guide for Set of Data Elements to Describe a Groundwater Site
• ASTM D5521/D5521M - Guide for Development of Groundwater Monitoring Wells in Granular Aquifers
• ASTM D5254/D5254M - Practice for Minimum Set of Data Elements to Identify a Groundwater Site

Referencing these standards ensures a holistic approach to groundwater monitoring well design, operation, maintenance, and data management.

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Keywords: groundwater monitoring well, well maintenance, well rehabilitation, sample quality, environmental monitoring, ASTM D5978, well performance, biofouling, groundwater sampling, environmental compliance.

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: D5978/D5978M − 16 (Reapproved 2024)
Standard Guide for
Maintenance and Rehabilitation of Groundwater Monitoring
Wells
This standard is issued under the fixed designation D5978/D5978M; 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.
INTRODUCTION
This guide for maintenance and rehabilitation promotes procedures appropriate to groundwater
monitoring wells installed to evaluate the extent and nature of contamination, progress of remediation,
and for long-term monitoring of either water quality or water level.
1. Scope responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter-
1.1 This guide covers an approach to selecting and imple-
mine the applicability of regulatory limitations prior to use.
menting a well maintenance and rehabilitation program for
1.6 This guide offers an organized collection of information
groundwater monitoring wells. It provides information on
or a series of options and does not recommend a specific
symptoms of problems or deficiencies that indicate the need for
course of action. This document cannot replace education or
maintenance and rehabilitation. It is limited to monitoring
experience and should be used in conjunction with professional
wells, that are designed and operated to provide access to,
judgment. Not all aspects of this guide may be applicable in all
representative water samples from, and information about the
circumstances. This ASTM standard is not intended to repre-
hydraulic properties of the saturated subsurface while minimiz-
sent or replace the standard of care by which the adequacy of
ing impact on the monitored zone. Some methods described
a given professional service must be judged, nor should this
herein may apply to other types of wells although the range of
document be applied without consideration of a project’s many
maintenance and rehabilitation treatment methods suitable for
unique aspects. The word “Standard” in the title of this
monitoring wells is more restricted than for other types of
document means only that the document has been approved
wells. Monitoring wells include their associated pumps and
through the ASTM consensus process.
surface equipment.
1.7 This international standard was developed in accor-
1.2 This guide is affected by governmental regulations and
dance with internationally recognized principles on standard-
by site specific geological, hydrogeological, geochemical,
ization established in the Decision on Principles for the
climatological, and biological conditions.
Development of International Standards, Guides and Recom-
1.3 Units—The values stated in either inch-pound units or
mendations issued by the World Trade Organization Technical
SI units presented in brackets are to be regarded separately as
Barriers to Trade (TBT) Committee.
standard. The values stated in each system may not be exact
equivalents; therefore, each system shall be used independently
2. Referenced Documents
of the other. Combining values from the two systems may
2.1 ASTM Standards:
result in non-conformance with the standard.
D653 Terminology Relating to Soil, Rock, and Contained
1.4 All observed and calculated values shall conform to the
Fluids
guidelines for significant digits and rounding established in
D3740 Practice for Minimum Requirements for Agencies
Practice D6026, unless superseded by this standard.
Engaged in Testing and/or Inspection of Soil and Rock as
Used in Engineering Design and Construction
1.5 This standard does not purport to address all of the
D4044/D4044M Test Method for (Field Procedure) for In-
safety concerns, if any, associated with its use. It is the
stantaneous Change in Head (Slug) Tests for Determining
This guide 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. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved March 15, 2024. Published March 2024. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 1996. Last previous edition approved in 2016 as D5978 – 16. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/D5978_D5978M-16R24. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5978/D5978M − 16 (2024)
Hydraulic Properties of Aquifers (Withdrawn 2024) 3.2.2.1 Discussion—Maintenance includes both physical ac-
D4412 Test Methods for Sulfate-Reducing Bacteria in Water tions taken at the well and the documentation of those actions
and Water-Formed Deposits and all operating data in order to provide benchmarks for
D4448 Guide for Sampling Ground-Water Monitoring Wells comparisons at later times. Desired level of well performance
D4750 Test Method for Determining Subsurface Liquid can vary depending on the design objectives.
Levels in a Borehole or Monitoring Well (Observation
3.2.3 well preventive maintenance, n—any well mainte-
Well) (Withdrawn 2010)
nance action that is initiated for the purpose of meeting some
D5088 Practice for Decontamination of Field Equipment
preestablished rule or schedule that applies while well perfor-
Used at Waste Sites
mance is still within preestablished ranges.
D5092/D5092M Practice for Design and Installation of
3.2.4 well reconstructive maintenance, n—any preventive or
Groundwater Monitoring Wells
rehabilitative well maintenance action involving the replace-
D5254/D5254M Practice for Minimum Set of Data Ele-
ment of a major component (for example, pump, surface
ments to Identify a Groundwater Site (Withdrawn 2019)
protection).
D5299/D5299M Guide for Decommissioning of Groundwa-
3.2.5 well redevelopment, n—any preventive or rehabilita-
ter Wells, Vadose Zone Monitoring Devices, Boreholes,
tive well maintenance action, taken after start-up, for the
and Other Devices for Environmental Activities
purpose of mitigating or correcting deterioration of the filter
D5408 Guide for Set of Data Elements to Describe a
pack or adjacent geologic formations, or both, due to the well’s
Groundwater Site; Part One—Additional Identification
presence and operation over time, usually involving physical
Descriptors (Withdrawn 2019)
development procedures, applied in reaction to deterioration.
D5409/D5409M Guide for Set of Data Elements to Describe
a Groundwater Site;Part Two—Physical Descriptors 3.2.6 well rehabilitation, n—for the purposes of this guide,
(Withdrawn 2019)
synonymous with well rehabilitative or restorative mainte-
D5410 Guide for Set of Data Elements to Describe a nance.
Groundwater Site;Part Three—Usage Descriptors (With-
3.2.7 well rehabilitative or restorative maintenance, n—any
drawn 2016)
well maintenance action that is initiated for the purpose of
D5472/D5472M Practice for Determining Specific Capacity
correcting well performance that has moved outside of pre-
and Estimating Transmissivity at the Control Well
established ranges.
D5474 Guide for Selection of Data Elements for Groundwa-
ter Investigations (Withdrawn 2021) 4. Significance and Use
D5521/D5521M Guide for Development of Groundwater
4.1 The process of operating any engineered system, such as
Monitoring Wells in Granular Aquifers
monitoring wells, includes active maintenance to prevent,
D5753 Guide for Planning and Conducting Geotechnical
mitigate, or reverse deterioration. Lack of or improper main-
Borehole Geophysical Logging
tenance can lead to well performance deficiencies (physical
D6026 Practice for Using Significant Digits and Data Re-
problems) or sample quality degradation (chemical problems).
cords in Geotechnical Data
These problems are intrinsic to monitoring wells, which are
2.1.1 In addition, ASTM Volume 11.01 on Water (I) and
often left idle for long periods of time (as long as a year),
Volume 11.02 on Water (II) contain numerous test methods and
installed in non-aquifer materials, and installed to evaluate
standards that may be of value to the user of this guide.
contamination that can cause locally anomalous hydrogeo-
D7726 Guide for The Use of Various Turbidimeter Tech-
chemical conditions. The typical solutions for these physical
nologies for Measurement of Turbidity in Water
and chemical problems that would be applied by owners and
operators of water supply, dewatering, recharge, and other
3. Terminology
wells may not be appropriate for monitoring wells because of
3.1 Definitions:
the need to minimize their impact on the conditions that
3.1.1 For definitions of common technical terms in this
monitoring wells were installed to evaluate.
standard, refer to Terminology D653.
4.2 This guide covers actions and procedures, but is not an
3.2 Definitions of Terms Specific to This Standard:
encyclopedic guide to well maintenance. Well maintenance
3.2.1 well development, n—actions taken during the instal-
planning and execution is highly site and well specific.
lation and start-up of a well for the purpose of mitigating or
4.3 The design of maintenance and rehabilitation programs
correcting damage done to the adjacent geologic formations
and the identification of the need for rehabilitation should be
and filter materials that might affect the well’s ability to
based on objective observation and testing, and by individuals
produce representative samples.
knowledgeable and experienced in well maintenance and
3.2.2 well maintenance, n—any action that is taken for the
rehabilitation. Users of this guide are encouraged to consult the
purpose of maintaining well performance (see Discussion) and
references provided.
extending the life of the well to provide samples that are
representative of the groundwater surrounding it. 4.4 For additional information see Test Methods D4412,
D5472/D5472M, D7726 and Guides D4448, D5254/D5254M,
D5521/D5521M, D5409/D5409M, D5410 and D5474.
The last approved version of this historical standard is referenced on
www.astm.org. NOTE 1—The quality of the result produced by this standard is
D5978/D5978M − 16 (2024)
dependent on the competence of the personnel performing it, and the
5.3.4 Loss of Production—Usually caused by pump failure,
suitability of the equipment and facilities used. Agencies that meet the
but can also be caused by dewatering, plugging, or well
criteria of Practice D3740 are generally considered capable of competent
collapse.
and objective testing/sampling/inspection/etc. Users of this standard are
5.3.4.1 Well Collapse—Can be caused by tectonism, ground
cautioned that compliance with Practice D3740 does not in itself assure
reliable results. Reliable results depend on many factors; Practice D3740
subsidence, failure of unsupported casing (that is, in caves or
provides a means of evaluating some of those factors.
because of faulty grout), corrosion and subsequent failure of
Practice D3740 was developed for agencies engaged in the testing
screen and casing, improper casing design, local site
and/or inspection of soils and rock. As such, it is not totally applicable to
operations, freeze-thaw, or improper chemical or mechanical
agencies performing this practice. However, user of this practice should
recognize that the framework of Practice D3740 is appropriate for rehabilitation.
evaluating the quality of an agency performing this practice. Currently
5.3.5 Observation of physical damage or other indicator.
there is no known qualifying national authority that inspects agencies that
perform this practice.
6. Sample Quality Degradation
5. Well Performance Deficiencies
6.1 All of the preceding physical well performance deficien-
cies can result in sample quality degradation by dilution,
5.1 Proper well design, installation, and development can
cross-contamination, or entrainment of solid material in water
minimize well performance deficiencies that result in the need
samples. In addition, chemical and biological activity can both
for maintenance and rehabilitation. Practice D5092/D5092M
degrade well performance and sample quality. Any change in
and Guide D5521/D5521M should be consulted. Performance
well or aquifer chemistry that results from the presence of the
deficiencies include: sand, silt, and clay infiltration; low yield;
well can interfere with accurate characterization of a site.
slow responses to changes in groundwater elevations; and loss
of production.
6.2 Physical Indicators—Chemical and biological activity
that can lead to sample quality degradation include:
5.2 Preventable Causes of Poor Well Performance:
6.2.1 Chemical Encrustation—Precipitation of calcium or
5.2.1 Inappropriate well location or screened interval. These
magnesium carbonate or sulfate, iron, or sulfide compounds
may be unavoidable if a requirement for site characterization or
can reduce well yield and specific capacity.
monitoring exists;
6.2.2 Biofouling (Biological Fouling)—Microbial activity
5.2.2 Inappropriate drilling technique or methodology for
can result in slime production and the precipitation of iron,
materials screened;
manganese, or sulfur compounds and occasionally other
5.2.3 Inadequate intake structure design (screen, filter
materials, such as aluminum oxides. Biofouling may be ac-
material, and so forth);
companied by corrosion or encrustation, or both, and can result
5.2.4 Inappropriate well construction materials. This may
in reduced specific capacity and well yield. Biochemical
lead to corrosion or collapse;
deposits can interfere with sample quality by acting as chemi-
5.2.5 Improper construction, operation, or maintenance, or
cal sieves.
combination thereof, of borehole or well, wellhead protection,
6.2.3 Corrosion—Corrosion of metal well and pump com-
well cap, and/or locking device;
ponents (that is, stainless steel, galvanized steel, carbon steel,
5.2.6 Ineffective development;
and low carbon steel) can result from naturally aggressive
waters (containing H S, NaCl) or electrolysis. The presence of
5.2.7 Inappropriate pump selection; and
contaminants contributes to corrosion through contributions to
5.2.8 Introduction of foreign substances.
microbial corrosion processes and formation of redox gradi-
5.3 Physical Indicators of Well Performance Deficiencies
ents. Non-aqueous phase solvents may degrade PVC and other
Include:
plastics. Other environmental conditions such as heat or
5.3.1 Sand, Silt, and Clay Infiltration—Causes include in-
radiation may contribute to material deterioration (such as
appropriate and inadequate well drilling (for example, auger
enhanced embrittlement). Metals such as nickel or chromium
flight smearing), improper screen and filter pack, improper may be leached from corroding metals. Degradation of plastic
casing design or installation, incomplete development, screen
well components may result in a release of monomers (such as
corrosion, or collapse of filter pack. In rock wells, causes vinyl chloride) to the environment (see Note 2).
include the presence of fine material in fractures. The presence
NOTE 2—Naturally aggressive (for metals) waters have been defined as
of sand, silt, or clay can result in pump and equipment wear
low pH (<7.0), high DO (>2 mg/L), high H S (>1 mg/L), high dissolved
and plugging, turbid samples, filter pack plugging, or combi- −
solids (>1000 mg/L), high CO (>50 mg/L), and high Cl content (>500
nation thereof.
mg/L). However, local conditions may result in corrosion at less extreme
values. Expression of corrosion is also dependent on materials load.
5.3.2 Low Yield—Causes include dewatering, collapse or
consolidation of fracture or water-bearing zone, pump mal-
6.2.4 Change in Turbidity—Causes include biofouling and
function or plugging, screen encrustation or plugging, and
intake structure, screen or filter pack clogging or collapse.
pump tubing corrosion or perforation or clogging.
Increase in turbidity may not always be the result of a problem
5.3.3 Water Level Decline—Causes include area or regional with the well. Changes in the purging and sampling procedures
water level decline, well interference, and chemical or micro- and devices used can affect the turbidity of water from a
bial plugging or encrustation of the borehole, screen, or filter monitoring well. For example, using a bailer where a pump
pack. was previously utilized, or pumping at a higher rate than
D5978/D5978M − 16 (2024)
previously used could increase turbidity; likewise, pumping a 7.2.2 A maintenance plan includes those practices, includ-
well that was previously bailed could increase turbidity. ing preventive design and construction practices (see 5.1), an
6.2.5 Change in Sand/Silt Content or Particle Counts— assessment of identified and potential problems (see 5.2, 6.1,
Causes include biofouling (resulting in clogging or sloughing) 6.2), procedures for how these potential problems will be
and intake structure clogging or collapse. Increase in the monitored and evaluated (see Sections 6 and 7), and a
sand/silt content may not always be the result of a problem decision-making process on how to proceed to address prob-
with the well. Changes in the purging and sampling procedures lems as they occur.
and devices used can affect the sand/silt content of water from 7.2.2.1 The decision-making process should include, as a
a monitoring well. For example, using a bailer where a pump minimum, who will make the decisions based on what criteria,
was previously utilized, or pumping at a higher rate than a set of alternatives such as establishing a program of preven-
previously used could increase the sand/silt content; likewise, tive treatment, replacing components on an as-needed basis,
pumping a well that was previously bailed could increase the and how to proceed if more intrusive rehabilitation or decom-
sand/silt content. missioning is needed. This decision-making process should be
triggered if there are changes in condition or performance
6.3 Chemical Indicators (Observed in Groundwater
detected in routine monitoring that show deterioration or the
Samples)—Chemical and biological activity that can lead to
potential to affect the well’s ability to provide acceptable
sample quality degradation include (see Note 3):
information. The decision-maker must decide what the stan-
NOTE 3—Changes in chemical indicators can also be a result of
dards are and the importance of detected changes. It is
site-wide changes in hydro-geochemistry.
understood that there is no single level of performance or
2+ 3+
6.3.1 Iron (Changes in Total Fe, Fe /Fe , Iron Minerals maintenance standards that exists or is possible due to the
and Complexes)—Causes include corrosion, changes in redox
individual character of wells and site conditions.
potential, and biofouling.
7.2.3 In setting the goal(s) for an acceptable level of
2+ 4+
6.3.2 Manganese (Changes in Total Mn, Mn /Mn , Man-
performance, the users of this guide should keep in mind what
ganese Minerals and Complexes)—Causes include changes in
is possible in a given situation and evaluate whether desired
redox potential and biofouling.
standards can be met. The decision process should include
2− 0 2−
6.3.3 Sulfur (Changes in Total S /S /SO , Sulfur Miner-
personnel with special knowledge or skill in well maintenance
als and Complexes)—Causes include changes in redox poten-
and rehabilitation, especially field or contractor personnel with
tial and biofouling. direct experience in these activities. The well owner or
6.3.4 Changes in Redox Potential (Eh)—Causes include responsible party should be informed of the preventative
microbial activity and changes in O , CH , CO , N, S, Fe, and maintenance program and its goals.
2 4 2
Mn species present in the system.
7.3 Maintenance Program Design—The design of a main-
6.3.5 Changes in pH—Causes include corrosion; microbial
tenance program should incorporate all available information
activity; dissolved gases such as oxygen, carbon dioxide, and
about site-specific factors that could cause sand, silt, or clay
hydrogen sulfide; and encrustation.
infiltration, sample turbidity or alteration, corrosion, or clog-
6.3.6 Changes in Conductivity—Causes include changes in
ging. Such information can include biological activity, redox
tot
...