CEMP-RA

Engineer Pamphlet

1110-1-27

Department of the Army

U.S. Army Corps of Engineers

Washington, DC 20314-1000

EP 1110-1-27

27 January 2000

Engineering and Design

OPERATION AND MAINTENANCE OF

EXTRACTION AND INJECTION WELLS

AT HTRW SITES

Distribution Restriction Statement

Approved for public release;

distribution is unlimited.
CEMP-RA 

DEPARTMENT OF THE ARMY 

U.S. Army Corps of Engineers 

Washington, DC 20314-1000 

EP 1110-l-27 

Pamphlet 

No. 111 O-1 -27 27 January 2000 

Engineering and Design 

OPERATION AND MAINTENANCE OF EXTRACTION 

AND INJECTION WELLS AT HTRW SITES 

1. Purpose. This engineer pamphlet transmits a document which describes requirements for carrying 

out Operations & Maintenance (O&M) for extraction and injection wells at HTRW sites. 

of this document contains logs and checklists to be used during O&M of extraction or injection wells, 

or to review O&M plans submitted by contractors. 

2. Applicability. This pamphlet applies to HQUSACE elements, and all USACE commands, having 

responsibility for preparing or reviewing O&M plans for extraction and injection wells at HTRW sites. 

3. Distribution Statement. Approved for public release, distribution is unlimited. 

4. References. Required and related publications are listed in Appendix A, 

5. Explanation of Abbreviations and Terms. Special terms used in this pamphlet are explained in 

Appendix B. 

FOR THE COMMANDER: 

4 Appendices UL 

(See Table of Contents) Major General, USA 

Chief of Staff 
i

DEPARTMENT OF THE ARMY EP 1110-1-27

 U.S. Army Corps of Engineers

CEMP-RA Washington, DC 20314-1000

Pamphlet

No. 1110-1-27 27 January 2000

Engineering and Design

OPERATION AND MAINTENANCE OF

EXTRACTION AND INJECTION WELLS AT HTRW SITES

Table of Contents

Subject Paragraph Page

Chapter 1

Introduction

Purpose 1-1 1-1

Applicability 1-2 1-1

References 1-3 1-1

Distribution Statement 1-4 1-1

Safety 1-5 1-2

Scope and Application 1-6 1-2

Terminology 1-7 1-2

Basis 1-8 1-3

Chapter 2

Suggested Minimum Baseline Data for Each Well

Causes of Well Problems 2-1 2-1

Well Tests: Purpose and Description 2-2 2-4

Specific Capacity Data 2-3 2-6

Development Data 2-4 2-7

Well Construction Diagram 2-5 2-9

Construction Boring Log 2-6 2-9

Pump, Flow Meter, Pressure, Electrical, and other Monitoring 2-7 2-10

Ground Water Geochemistry: Hazardous and Nonhazardous 2-8 2-13

Biological Assay 2-9 2-16

Field Data Reporting and File Documentation 2-10 2-17

Chapter 3

Historical Data: Influence on Pumping/Injection and

Drawdown Results

General 3-1 3-1

Pumping Rates 3-2 3-1

Wellhead Pressure 3-3 3-1

Water-Level Data 3-4 3-2
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Subject Paragraph Page

Piezometric Data 3-5 3-2

Electrical (Power) Data 3-6 3-2

Video for Historical Comparison 3-7 3-3

Piezometric Maps 3-8 3-3

Geologic Regime 3-9 3-3

Maintenance Logs for Individual Wells 3-10 3-3

Downtime History 3-11 3-4

Chapter 4

Data Evaluations and Troubleshooting in Well System

Maintenance

Institutional and Funding Issues in Maintenance Planning, Analysis and

Execution

4-1 4-1

Quarterly Review of Site Performance Data 4-2 4-2

Baseline and Historical Data for Wells/Site 4-3 4-2

Operator/Working Crew Leader Qualifications and Training 4-4 4-3

Determination of Operational Maintenance Responsibilities 4-5 4-3

Biological Activity Implications 4-6 4-4

Impacts on Plant 4-7 4-5

Chapter 5

Schedule of Maintenance Actions for Wells

Well and Plant Maintenance Schedule Overview 5-1 5-1

Minimum and Optimal Regular Schedule for First Year 5-2 5-1

Schedule for Reducing Maintenance After First Year 5-3 5-4

Schedule for Intensive Maintenance for Critical Wells 5-4 5-4

Chapter 6

Chemical Dosage for Wells

Lists of Chemicals to be Used 6-1 6-1

Use and Interpretation of MSDS 6-2 6-5

Calculation Work Sheets 6-3 6-5

Chapter 7

Health and Safety Concerns

Health and Safety Plan 7-1 7-1

Level of Protection for Mixing and Well Application 7-2 7-1

Chemical Handling Hazards 7-3 7-1

Mixing Chemicals 7-4 7-1

Chapter 8

Checklists

Type and Frequency of Data to be Collected 8-1 8-1

Well Maintenance Log 8-2 8-1

O&M Calculation Work Sheet 8-3 8-1

Other Records 8-4 8-1
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Subject Paragraph Page

Chapter 9

Suggested Maintenance (Minimum and Optimum)

Design Aspects 9-1 9-1

Chemical Addition 9-2 9-4

Mechanical Agitation 9-3 9-4

Chemical Recovery 9-4 9-5

Well Development 9-5 9-5

Maintenance Monitoring Well Deterioration and Redevelopment

Evaluation

9-6 9-7

Chapter 10

O&M Equipment Needed

Overview 10-1 10-1

Example Basic Well Maintenance Field System 10-2 10-1

Provision of Maintenance Equipment 10-3 10-2

Appendix A

List of References and Bibliography

Appendix B

Explanations of Abbreviations and Terms

Appendix C

Experience Basis and Maintenance Treatment Example

Appendix D

Examples of Logs, Checklists, Calculations
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1-1

Chapter 1

Introduction

1-1. Purpose

a. This engineer pamphlet (EP) provides geotechnical, chemical, microbial, and operational

guidance for U.S. Army Corps of Engineers (USACE) elements in identifying aspects of groundwater

extraction and injection wells and systems that have led to failures of either the extraction and injection

wells or related piping and treatment systems at hazardous, toxic, and/or radioactive waste (HTRW) sites.

These guidelines are a compilation of specific problems that have been identified in each of several

categories, along with a technical discussion of their diagnoses and solutions.

b. This EP provides the multidisciplinary guidance needed to:

(1) Sustain the performance of ground water extraction and injection systems so that site mission

(ground water cleanup) failure does not occur.

(2) Delay substantial, radical rehabilitation of these systems as long as possible.

c. This EP will provide:

(1) Background and rationale for well maintenance problems.

(2) Demonstrated prevention and remedial methods for wells.

(3) Specific guidance in applying solutions.

d. This background and associated recommendations will be based on experience and applied

research by USACE, its contractors, and other experienced parties.

e. The USACE and the programs it oversees in HTRW ground water remediation have the

responsibility to ensure that the projects fulfill their mission of cleaning up ground Water to the extent

necessary (defined by risk analysis or legal maximum contaminant levels (MCLs)) to protect human

health and the environment where technically feasible. Pumping and injection well systems are integral

parts of these efforts on many sites. It is the management's responsibility to ensure that well systems

installed continue to function at the optimal level.

1-2. Applicability

This EP applies to all USACE Commands having Civil Works and/or Military Programs HTRW project

responsibilities.

1-3. References

Required and related publications are listed in Appendix A.

1-4. Distribution Statement

Approved for public release; distribution is unlimited.
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1-2

1-5. Safety

Personal safety is the top priority in any operations on HTRW sites. The guidance in this EP is provided

with safety in mind. However, users of this pamphlet are responsible for following the requirements of

EM 385-1-1 and ER 385-1-92.

1-6. Scope and Application

a. Scope. This EP is concerned with the operation and maintenance (O&M) of ground water

injection and extraction systems on HTRW sites; however, it does not address the rehabilitation of these

systems (that is, the actions taken to restore a well after substantial loss of performance), although

maintenance operations will have some similarities with rehabilitation. The scope also excludes the O&M

of the water treatment plant facility. Other pumping or injection wells besides those at HTRW sites (for

example, ground water monitoring wells or water supply and injection wells for purposes other than

HTRW cleanup) have performance and water quality problems associated with well deterioration. Also,

monitoring wells (for either HTRW or preventive monitoring) may become clogged and no longer

provide reliable samples for water quality analysis. While not specifically addressed to these applications,

many features of the diagnosis and maintenance treatments will also apply to these other wells.

(1) Performance. This EP will emphasize the role of preventive design and construction (based on

good quality data and practice) in preventing or delaying problems. It is assumed that wells on HTRW

sites will

• operate under conditions that often promote rapid well performance deterioration.

• need to be designed and operated in such a way that unavoidably promotes well performance

problems.

(2) Effects of past design and maintenance. The EP also addresses situations where installation

operators are required to maintain well systems that were not optimally designed in the first place. In

studying the operating challenges of such systems, it has become apparent that some O&M practices for

HTRW site well systems are ineffective, and obsolete processes are being followed that do not reflect

modern understanding of microbial and geochemical processes. This EP is intended to provide guidance

to update O&M processes, taking into consideration modern understandings to improve O&M

effectiveness.

b. Application. The specific application of and adherence to these guidelines must be tailored to

each project function, the contaminants of concern, the adopted treatment solution, local geohydrologic

properties, geotechnical judgment, available resources, applicable regulatory requirements, policy and

guidance, public concerns, and remediation goals.

1-7. Terminology

Communication between regulatory, oversight, owner, and contractor personnel involved in the remediation of an HTRW site is important both before and during remediation of the site. Communication is

complicated by the involvement of numerous technical disciplines and regulatory agencies, and it is

imperative that the descriptive language used during discussions be compatible. Likewise, the practices of

well design, construction, and maintenance and rehabilitation also have specific terminology and usages.

This EP promotes an interdisciplinary approach to well-system design and O&M that works to enhance

system performance. The reader is assumed to be a technically competent person who may not be familiar

with all specific terminology usages, but has a general but not thorough knowledge of ground water and

well-system construction. Therefore, a wide range of definitions will be supplied to promote clarity.
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1-3

a. Definitions.

(1) EM 1110-1-4000 provides definitions for terms in the following topical areas:

• Drilling and well installation plan/drilling plan.

• Field activity (FA).

• Field drilling organization (FDO).

• Geotechnical data quality management.

• Hazardous and/or toxic waste.

• Well redevelopment/rehabilitation.

• Screened interval.

• Site Safety and Health Plan (SSHP).

• Well development.

(2) Additional industry (e.g., National Groundwater Association, American Water Works

Association (AWWA) Research Foundation, American Society for Testing and Materials (ASTM)) and

international sources of definitions were used in preparation of this pamphlet. Several relevant documents

provide lists of definitions specific to the O&M of wells, particularly Borch, Smith, and Noble (1993),

Cullimore (1993), Driscoll (1986), Helweg, Scott, and Scalmanini (1983), Smith (1992), and Alford and

Cullimore (1999). ASTM Standard Guides cited herein (e.g., D 5978, Standard Guide for Maintenance

and Rehabilitation of Ground-Water Monitoring Wells) also provide definitions of specific terms used.

(3) Some technical terms have come to be commonly used in specific ways in well maintenance

activities and are frequently used in this pamphlet. Most of these relate to causes of problems. Others are

used in specific ways in this pamphlet and are defined in Appendix B.

1-8. Basis

The basis for the information and recommendations contained in this pamphlet is experience in actual

operations. Relevant case history information is published in Leach et al. (1991); Smith (1995); and

Alford and Cullimore (1999).
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2-1

Chapter 2

Suggested Minimum Baseline Data for Each Well

2-1. Causes of Well Problems

a. Cause summary. HTRW well-system problems have a number of identified causes (Driscoll

1986; Borch, Smith, and Noble 1993; Smith 1995; Alford and Cullimore 1999) that often work together

to produce conditions encountered on the well site. Table 2-1 summarizes problems with wells.

b. Symptom determination. In many cases, symptoms of well deterioration may not be apparent

until well performance is severely impaired, unless the results of system water and quality and

performance monitoring are compared over time to establish trends. Such problems can be prevented and

mitigated by effective O&M, but to do so requires valid information on the environment, hydrology, and

material performance of the well system produced by information collection in the process known as

“maintenance monitoring.”

c. Purpose of maintenance monitoring. Maintenance monitoring is one aspect of well problem

prevention, and includes maintenance and rehabilitation that is employed to provide early detection of

deterioration of wells. The ideal situation is to detect deteriorating effects in time to prevent problems or

allow the easiest possible treatment. Table 2-2 summarizes useful well information to collect for

troubleshooting and predicting problems.

d. Minimum analysis goals. At a minimum, a preventive maintenance (PM) monitoring program

should provide regular analyses to determine:

• Whether a deteriorating condition may be occurring.

• The reasons for changes in well and pump performance and water quality as soon as the

changes can be detected.

e. PM monitoring information use. In order for O&M to make use of such information over time:

• A maintenance system must have organized and accessible records.

• Information collection should begin with the project design phase and continue throughout

the working life of the extraction and injection system.

• Records must be regularly reviewed by qualified personnel.

f. Adjusting maintenance monitoring protocols. In general maintenance monitoring approaches

should be tried and reviewed over a period of time and adjusted based on experience. They must be

implemented as part of a systematic maintenance program involving:

• Institutional commitment.

• A goal of deterioration prevention.

• Systematic monitoring as part of site maintenance procedures.

• A method evaluation of information to determine what maintenance actions are necessary.

In any case, it has to be recognized that monitoring approaches and responses will be site specific, and

likely will require adjustment during implementation.
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2-2

Table 2-1. Definitions of Poor Well Performance and Causes

Problems Causes

Sand/Silt Pumping: Pump and

equipment wear and plugging.

Inadequate screen and filter-pack selection or installation, incomplete

development, screen corrosion, collapse of filter pack due to washout

resulting from excessive vertical velocity in the filter pack, presence

of sand or silt in fractures intercepted by a well completed “openhole,” incomplete casing bottom seat (casing-screen break) or

casing-screen break due to settlement, ground movement, or poor

installation. Pumping in excess of gravel pack and system capacity

(oversized pump, pipe breakage lowering pumping head, etc.).

Silt/Clay Infiltration: Filter

clogging, sample turbidity.

Inadequate well casing seals, infiltration through filter pack, or "mud

seams" in rock, inadequate development, or casing-screen break due

to settlement, ground movement, or poor installation. Formation

material may be so fine that engineered solutions are inadequate.

Pumping Water Level

Decline: Reduced yields,

increased oxidation, well

interference, impaired pump

performance.

Area or regional water-level declines, pumping in excess of

sustainable well capacity, well interference, or well plugging or

encrustation. Sometimes a regional decline will be exaggerated at a

well due to plugging.

Injection water level rise and

reduced acceptance rate or

increased injection system

head.

Area or regional water-level rise; injection in excess of sustainable

well capacity; well plugging or encrustation; encrustation, plugging,

or corrosion and perforation of discharge lines; increased TDH in

water delivery system.

Lower (or Insufficient) Yield:

Unsatisfactory system

performance.

Dewatering or caving in of a major water-bearing zone, pump wear

or malfunction, encrustation, plugging, or corrosion and perforation

of discharge lines, increased total dynamic head (TDH) in water

delivery or treatment system.

Complete Loss of Production:

Failure of system.

Most typically pump failure. Also loss of well production due to

dewatering, plugging, or collapse.

Chemical Encrustation:

Increased drawdown, reduced

output or reduced injection

acceptance rate.

Deposition of saturated dissolved solids, usually high Ca, Mg

carbonate, and sulfate salts or iron oxides, or FeII sulfides. May

occur at chemical feed points, e.g., feeding caustic soda to raise pH

into a Ca-rich water.

Biofouling Plugging:

Increased drawdown, reduced

output or reduced injection

acceptance rate, alteration of

samples, clogging of filters

and lines.

Microbial oxidation and precipitation of Fe, Mn, and S (sometimes

other redox-changing metals that are low solubility when oxidized)

with associated growth and slime production. Often associated with

simultaneous chemical encrustation and corrosion. Associated

problem: well "filter effect": samples and pumped water are not

necessarily representative of the aquifer. Often works simultaneously

with other problems such as silting.

Pump/Well Corrosion: Loss

of performance, sanding, or

turbidity.

Natural aggressive water quality, including H2S, NaCl-type waters,

biofouling and electrolysis due to stray currents. Aggravated by poor

engineered material selection.

Well Structural Failure: Well

loss and abandonment.

Tectonic ground shifting, ground subsidence, failure of unsupported

casing in caves or unstable rock due to poor grout support, casing or

screen corrosion and collapse, casing insufficient, local site

operations.
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Table 2-2. Parameters Useful in Well Maintenance Monitoring

Type Tests Parameters Obtained

Hydraulic testing Flow and drawdown for specific capacity (water

level rise in injection wells).

Total amount of pumping time and quantity

pumped per year.

Periodic step-tests for well and pump efficiency.

Power and fuel consumption for pump efficiency.

Total and ferric iron, and total manganese (and

other metals as indicated).

Important anions as identified, including sulfides,

sulfates, carbonates, and bicarbonates.

pH, conductivity, and redox potential (Eh) where

possible (instrument readings may be replaced by

checking ratios of Fe (total) to Fe2+ (soluble)).

Turbidity or total suspended solids calculation of

product water.

Physicochemical parameters (for changes due to

deterioration)

Calculation of corrosion/encrustation potential

using a consistent method.

Microbial Total Fe/Mn-related bacteria (IRB), sulfurreducing bacteria (SRB), slime-forming and other

microbial types of maintenance concern as

indicated.

Pump and other equipment inspection for

deterioration

Visual/physical

Borehole TV for casing and screen deterioration.

g. Incorporating PM data collection into the site data collection effort. Too often the significance

and central importance of data are overlooked in the context of the scope of the whole project. What may

seem to be minor clerical details to those responsible for a project's overall management can be important

later in site operations. The quality and completeness of boring logs, well completion diagrams, and well

testing, etc., are often left to contractors who do not appreciate the value of the data, or left to

inexperienced, overworked, or unsupervised junior technical staff. Omissions in the data are often

apparent only when it is too late to correct the deficiency.

(1) Data are easiest to obtain and more accurate if data collection is incorporated into the project

plan at the onset. There is a tendency to omit maintenance planning, data gathering, and repair costs when

bids are higher than budgeted, or to inadequately fund these tasks as costs are adjusted to available funds

during project management. Budgets to fund remediation activities themselves can be unrealistic in this

regard in not adequately considering the real costs of maintenance.

(2) Compiling data at a later stage of a project's operation is generally difficult and less

successful. The following sections describe the types of testing and information recommended, and how

the information should be collected, recorded, and managed, along with useful references and standards in

practical use. A minimum of baseline data on each well is needed to assess and interpret the well’s

performance through time. Specifications should assure that there are specific requirements for data

collection and analysis for O&M purposes.
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2-2. Well Tests: Purpose and Description

a. General. Reliable, valid tests are critical to well assessment and management. Such assessment

and management is enhanced by a history of valid well data over time, back to installation if possible

(Chapter 3). Valid results depend on their reliable, valid, and reproducible test design, performance,

reporting, and interpretation. In practice, performance and proper reporting of results lag behind

performance standards. This pamphlet briefly reviews pumping test types and how they are used to assess

pump, well, and pumped-formation (aquifer) parameters. It describes minimum valid baseline data to be

reported, including

• Minimum data standards for tests.

• Minimum data for individual water level measurements (not just final levels), pumping rates,

sand (particulate) or colloidal content, and information on conditions that would affect

results.

• How to determine adequate testing intervals.

b. Data collection.

(1) Accurate discharge flow data are needed for any pumping test. All devices should be

calibrated prior to installation, and at regular intervals to ensure proper operation. Flow measurement

devices suitable for pumping tests include:

• Orifice weirs: Driscoll (1986) provides a detailed description of the necessary elements of the

construction and use of an orifice weir.

• Mechanical flow meters which may also be used.

• Sonic-based flow meters available that are accurate and well adapted to this application.

(2) Equally important are time and water level measurements throughout the test. The times of

measurements must be accurately reported and the water levels themselves reported accurately in decimal

units (for analysis input). If there is the potential for water cascading in the well during the test, fit the

well with a drawdown (stilling) tube to shield the water level probe from the cascading water and ensure

accurate water level measurements. Finally, the data must be recorded on a sheet specifically structured to

record and organize pumping test data (an example is supplied in Appendix D). Directly measuring

system gauge pressure is essential in evaluating pump performance and useful in making field decisions

on tests of relatively unknown wells or pumps.

c. Step-drawdown tests. Step-drawdown tests are probably the most valuable hydraulic testing

tool available for assessing well performance in the context of maintenance and rehabilitation. When

properly conducted and analyzed, they provide data on specific capacity and well and aquifer losses.

Additionally, from the analysis, well efficiency and drawdown and specific capacity at a given discharge

rate can be estimated.

(1) Conducting and analyzing step-drawdown tests are treated in detail in Kruseman and de

Ridder (1994). For porous medium aquifers, the Hantush-Bierschenk method of analysis is employed,

which is relatively straightforward. For fractured rock aquifers, Rorabaugh's method may be required,

which is less straight forward. A computer application to solve Rorabaugh's method, such as FASTEP

(Labadie and Helweg 1975), may be useful. Plate D-2 is an example step drawdown plot. Plates D-3 and

D-4 provide an analysis of the step-drawdown test charted in Plate D-2 to determine well and aquifer loss.

Plates are provided in Appendix D.
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2-5

(2) The utility of data derived from the step-drawdown test is in the ability to:

• Determine characteristics about both the well and the aquifer simultaneously (aquifer and

well loss).

• Extrapolate or interpolate the performance of the well at various discharge rates, using

measured data points as a reference.

• Determine the operating characteristics of the well pump used.

(3) If performed immediately after a well is constructed, the step-drawdown test provides an

estimate of the efficiency of the well and effectiveness of the well development phase of the well

construction, and the baseline well and pump performance for comparison in the future. First checks of a

well design’s criteria or assumptions can also be made and adjusted as needed. It is highly recommended

that all of these wells be pre-developed immediately after the well screen and filter pack are installed.

This procedure gives a far greater chance of removing both drilling fluid solids and natural fines, and of

replacing any of the filter pack that subsides due to consolidation, etc.

(4) Note that well loss does not increase linearly to the discharge rate; therefore, well efficiency

and specific capacity are not constant and decline with increasing discharge rate. This relationship makes

comparing well performance data through time and various discharge rates difficult without normalizing

the data to the same discharge rate. The equation describing well and aquifer loss to interpolate or

extrapolate pumping water levels should be used as needed. The equation can also be used to estimate

specific capacity and efficiency at the intended discharge rate. Changes in well performance will then be

apparent.

(5) For step-test data to be useful in calculating well, pump, and aquifer performance parameters:

• Data must be accurately gathered, with data collected at standard intervals of decreasing

frequency as recommended (Helweg, Scott, and Noble (1983), and Driscoll, 1986).

• Each step must be of a sufficient length of time for either the water level decline to stabilize

or the decline trend to be established on a semi-log plot of drawdown versus time (but does

not have to be long).

• The effects of interference (such as other wells turning on and off) must be factored into the

analysis.

(6) HTRW sites may impose restrictions on optimal step testing methodology. For example, a

five-step test with pressure measurement is recommended to determine pump wear. However, pumping

contaminated ground water requires collection of the fluid. Perfecting the gathering of pump wear data

from a three-step test, and learning to extrapolate from short steps may be a necessary compromise in

methodology.

d. Constant rate and slug tests. Constant rate pumping tests and slug tests (in which an

instantaneous charge of water or a solid object is introduced into a well) are employed predominantly to

determine aquifer characteristics, that is, transmissivity, hydraulic conductivity, and storage coefficient.

Their utility in well maintenance and rehabilitation is less direct than with step-drawdown tests, but data

derived from these tests can be used in preliminary calculations of expected well hydraulic parameters.

(1) Constant-rate pumping tests.

(a) With knowledge of aquifer characteristics, the theoretical drawdown in the aquifer at the well

screen for a given discharge rate can be calculated and compared with the observed drawdown at the
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same rate, yielding the well efficiency at that rate. As a constant rate test approaches steady-state, the final

specific capacity at the discharge rate can be calculated. Neither the constant-rate or the slug test can

provide the means for predicting the well loss and the well efficiency that occurs over a range of

discharge rates. A step-drawdown test is needed.

(b) The constant rate test is conducted similarly to the step-drawdown test. As with the stepdrawdown test, accurate discharge, water level, and time measurements are essential. Again, Kruseman

and de Ridder (1994) provide an in-depth discussion of conducting and analyzing these tests. Computer

applications are available to aid in the analysis of constant rate tests. Boulding (1995) provides a useful

conceptual review of pumping test software which can be updated by research into current products.

(2) Slug tests. A slug test is also used to determine aquifer characteristics, not well performance,

and involves a different procedure and methods of analysis.

(a) Descriptions of procedures and methods of analysis are provided in Kruseman and de Ridder

(1994), Bouwer and Rice (1976), Hvorslev (1951), and ASTM D 4044, D 4050, and D 4104. The

computer applications available to aid in the analysis of constant rate tests, such as AQUITEST (Walton

1996), also provide analysis of slug tests. Because of the small volumes of water involved and the short

(or long) time span over which the test occurs, pressure transducers and digital data logging are generally

employed. Pressure tranducers are submerged in the well and register the pressure of the column of water

overlying them. Water-level changes are detected as changes in pressure as the height of the overlying

water column either increases or decreases. The data logger can be programmed to sample and record

data from the transducer at required time intervals. This feature of digital data logging is most useful

when conducting slug tests in high-permeability sediments where many water level measurements will be

required over a span of seconds as the water level rapidly recovers.

(b) As with constant rate pumping test data, calculations of aquifer characteristics based on slug

test data can be used for estimation of theoretical well mounding in injection wells.

2-3. Specific Capacity Data

a. Definitions. Specific capacity is a term used to express the productivity of a well, and is

defined as Q/s, where Q is the discharge rate and s is the drawdown in the well (Driscoll 1986). The

observed drawdown in the well is a function of aquifer and well loss; therefore, Q/s is a term

incorporating both aquifer and well performance. Step-drawdown tests described in Section 2-2 provide a

means of separating the aquifer and well loss components.

b. Use of Q/s calculations. Q/s calculations, using water-level change and well pumping data, are

used to assess pumping well performance and results of development and redevelopment (Helweg, Scott,

and Scalmanini 1983; Driscoll 1986; Borch, Smith, and Noble 1993). The data that need to be collected

(Q and s in pumping wells) are simple to obtain and the calculations simple to make. Specific capacity

and specific acceptance are relatively sensitive indicators of hydraulic performance change in wells.

Making valid calculations in turn depends on reliable data collection. Appropriate actions in response to

changing values depend on setting action levels that permit a response before performance is seriously

impaired.

c. Minimum data needed and standards for data gathering, reporting, and assessment. To

determine Q/s for a well, accurate static water-level, pumping water-level, and discharge rate data are

needed. Since the water table or potentiometric surface varies seasonally and with outside stresses, a

deeper pumping water level for a given discharge rate may not reflect a change in the well performance.

Therefore, some means will be required to determine the variation in the static water level, e.g., an
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observation well outside the influence of the pumping well or static water levels obtained when the well is

not pumped.

d. Effects on Q/s calculations. Static and pumping water levels can be affected by oscillations

caused by the pump, cascading water, the water level probe becoming entangled in wiring and pump

column, and operator error.

(1) Many problems can be avoided by installing a stilling (drawdown) tube in the well. Also,

clearly establishing the "measuring point" (MP) of the well from which all measurement are taken and

informing all personnel who will be collecting data of the MP will avoid many problems. The discharge

rate can vary in response to system back-pressure and changes in pump performance, and therefore cannot

be assumed to be constant. It should be measured along with water levels when determining Q/s. The

flow meter used to measure the discharge rate is also subject to error as it wears or clogs.

(2) It is desirable that a baseline Q/s be determined at the intended discharge rate when a well is

constructed (assuming the efficiency of the well is acceptable). Subsequent measurements of the

drawdown in the well and discharge rate and recalculation of Q/s will provide an indication of the

ongoing performance of the well (Borch , Smith, and Noble, 1993; Howsam, P., Misstears, B., and Jones,

C. 1995). See Chapters 4 and 5.

2-4. Development Data

a. Purposes of development. In well construction, development has three purposes:

•Repair damage done to the aquifer during drilling.

•Set the filter pack.

•Increase the permeability of the aquifer in the vicinity of the well.

b. Redevelopment. Later, development activities may be a component of a maintenance program

to further the original development effort, or applied as a component of a maintenance program to

maintain or restore a well's performance. In this use, the processes are termed “redevelopment.”

c. Development process description and importance. Detailed descriptions of development and

redevelopment processes can be found in Australian Drilling Industry Training Committee Limited

(ADITC) (1997), Driscoll (1986), NGWA (1998), and ASTM D 5521 (in the context of monitoring

wells).

(1) Drilling method influence. The drilling method will, to some degree, modify or damage the

aquifer material in the process of drilling the hole. One must know what damage or modifications are

likely to have occurred in the aquifer material to judge the applicability or effectiveness of the development effort. This information is usually recorded on the drilling field log maintained by qualified

oversight personnel. Each lithologic material will be uniquely vulnerable to the drilling process and may

require specific development methods. Also, future performance problems may be related to aquifer

lithology. Different well construction methods will require different methods of development and the

construction of the well will determine what methods are applied in future activities. Additionally, the

type of drilling method used tends to influence the method of development (if cable tool: surge blocks and

bailers, if rotary: air compressors and pumps).

(2) Development methods. Well development includes as components many tools and methods

and the development data should include descriptions of the tools and methods utilized. For example:
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(a) If air lifting was applied, what was the size and capacity of the air compressor, at what depth

was the airline set?

(b) If surging was applied, what was the configuration of the surge block assembly, does the

diameter of the assembly match the casing and screen, through what intervals was it applied, and what

was the length and speed of the stroke?

(c) If jetting was applied, what was the configuration of the jetting tool, through what intervals

was is applied, etc. (nozzle velocity and distance from screen)?

(d) Other pertinent information, e.g., how much time was spent on each interval in cleaning.

(e) What predevelopment planning and decisions were made that would make development more

or less likely to be successful?

d. Development data gathering. Valid and complete development information is necessary to

assess results and to provide benchmarks for future development efforts. This information is recorded in a

well development log and collected with drilling and well construction log information (see example

forms in Appendix D). Minimum development information necessary includes:

(1) Drilling method description -- it affects development methods chosen and how field data are

reported.

(2) Description of development procedures used -- air lifting, jetting, surge blocking, etc.,

including descriptions of equipment and capacities (e.g., air compressor cubic feet per minute (cfm)

capacity).

(3) Time for each segment.

(4) Description of material drawn into well -- amount and type to determine its origin (need to

know if it is aquifer or well pack), standards of development and how measured.

e. Integration of development data with other data. Development information is merged with

step-drawdown data, well construction data, and lithologic data to provide insight into how the aquifer

material has been modified or is behaving through time in the vicinity of the well. This insight is crucial

for assessing changes in well performance and the appropriateness and effectiveness of maintenance and

rehabilitation efforts.

f. Development data gathered and significance.

(1) Development time. The effectiveness of even an appropriate development method is related to

the amount of time it is applied, and it must be determined if the time of application was sufficient for the

method to be effective. Development data should include the amount of time devoted to each of the tools

and methods mentioned above. The construction log may provide the amount of time devoted to

development, or the work crews' time sheets or daily log may also provide the time devoted.

(2) Development results. The data should include some form of documentation of the progress of

the development. Some drillers estimate changes in the discharge from the well during air lifting or

surging to indicate the progression of development. The driller may record a qualitative description of the

sediment and material removed from the well. A semi-quantitative record of the sediment concentration
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may be had from allowing samples to settle in a bucket, and a quantitative record may be available if

water samples were collected using an Imhoff cone or Rossum sampler. These and other methods are

discussed in Driscoll (1986).

(3) Well acceptance tests. Finally, data from well acceptance tests, usually a step-drawdown test

(Section 2-2), is helpful to document the effectiveness of the development. (As described in the

discussion on step-drawdown testing, the resulting efficiency of the well can be estimated from the

analysis of the test.)

2-5. Well Construction Diagram

“As constructed” well construction records are used in well maintenance to provide a basis for

comparison of past and present conditions, and for use in other calculations. At a minimum, diagrams

shall contain an accurate geographic location and precise designation used by the project, accurate depth,

diameter (including different components), casing and screen material type, screen slot size and screen

length, filter pack type, particle size and dimension, grout type and dimensions, and well equipment

descriptions and dates drilled and developed. ER 1110-345-700 provides general guidance for plan

components. EM 1110-1-4000 provides general guidance on well construction documentation. Plate 2-3

is an example well construction diagram.

2-6. Construction Boring Log

Boring logs include precise geographic location and boring identification (with cross reference to

subsequent well designations), accurate formation descriptions (including sediment and rock descriptions

provided according to uniform accepted standards with accurate depths), and particle size descriptions of

water-producing/accepting zones.

a. Lithologic log. The lithologic log is a record of the character, depths, and thickness of geologic

materials encountered by the drill as the borehole is advanced, with emphasis given to hydraulic

properties of the materials. Lithologic logs should be recorded and maintained by qualified oversight

personnel, using standard engineering or geologic terminology. EM 1110-1-4000 provides guidance on

sample logging, the data to be recorded, and examples of forms used to record the data.

(1) The lithologic/boring log should contain as a minimum.

(a) The depth at which geologic changes occur and at which samples are collected and described.

(b) A description of cutting samples collected at every change of geologic materials and at 1- to

11⁄2 -m (3.28- to 5-ft) intervals, and 100 percent logging for the screened interval in either the pilot or the

final boring.

(c) Changes in drilling action, that is, penetration rate, fluid loss, drilling noise, etc.

(2) Descriptions of unconsolidated sediments should note dominant grain size, sorting, and

estimates of relative percentages of sizes according to the Unified Soil Classification System (USCS)

procedures and those described in ASTM 421 and 422. Grain shape and rounding are useful for

estimating hydraulic properties. Color related to degree of weathering and oxidation-reduction is useful in

determining degree of saturation. Descriptions of consolidated bedrock should note degree of

cementation, induration, and fracturing. The depth at which saturated conditions occur should be noted.

Changes in drilling fluid properties (gains or losses of fluids, changing specific gravity, etc.) should be

noted, as they provide information on water-bearing zones.
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b. Borehole camera survey. High-resolution borehole camera (still or video) surveys provide a

means of recording lithology and fracture features in open boreholes, in addition to construction features.

The camera provides depth-specific images for interpretation of lithologic features; for example,

noticeable changes in formation color and texture, water cascading into the hole through fractures, and

fracture orientations.

2-7 Pump, Flow Meter, Pressure, Electrical, and other Monitoring

a. Equipment and material choice importance in data gathering.

(1) Purpose. Meeting data-gathering goals requires apparatus that will provide the most accurate

possible measurements. The equipment should be reliable and not distort measurements. To achieve these

goals, the equipment should be well matched to the data-gathering needs and well operational

environment.

(2) Material choices. The choice of materials to be used in devices for pumping and injection well

performance is important to well system life and quality of service. For example, in most situations,

where metals are specified, they should be stainless steel or other materials resistant to corrosion in the

water being extracted. Materials should be specified based on analysis and experience under the

environmental conditions to be found in the system. This requires analysis of the geochemistry of the

fluid (Section 2-8) and comparison to the reactivity of materials proposed for use. This analysis should

consider biological fouling and corrosion predictions (Section 2-9) because biofouling routinely

introduces clogging and corrosive conditions where they might not occur in sterile fluids. Discussions of

the material choice decision-making process are provided in numerous references (e.g., EM 1110-2-1914,

EM 1110-1-4000, EM 1110-1-4008, and Powers, 1992; Borch, Smith, and Noble 1993; Smith 1995; and

McLaughlan 1996 in the open literature specific to well maintenance).

(3) System component capacity. Pumps should be sized to closely match the well capacity and

match the flow requirements and pressure head conditions in the system being supplied.

(a) Poor sizing affects performance adversely. Pumping well capacity can be established by step

testing (Section 2-2). Flow and head conditions may be calculated, allowing for any likely fluctuations.

Should as-built conditions differ from design conditions, pump selection should be reviewed to ensure

that it matches the as-built hydraulics.

(b) EM 1110-1-4008 provides guidance in pump discharge head calculations. Pump sizing then

can commence using standard ground water industry well pump sizing procedures. TI 814-1 provides

sizing calculation procedures for submersible and vertical turbine pumps typical of remediation extraction

wells. Powers (1992) provides design sizing methods for vacuum and ejector pump systems often

employed.

(c) Once hydraulic head and flow conditions are used to design an ideal pump, comparisons can

be made to pump capacity charts or pump curves generated by manufacturers and provided in the

Contract Submittals (TM 5 813-9). See also discussion in Chapter 9 concerning material choices.

(d) An important feature is the location of the low water-level (lwl) shut-off, as specified by

CEGS 11212. Manual override of the pump controls should not bypass the lwl shut-off.

b. Monitoring measurement systems. To obtain necessary baseline data, reliable methods of

monitoring system parameters are needed.
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(1) Water-level measurement recommendations include:

• Water-level data may be collected manually or the process automated.

• For relatively small numbers of wells and conditions where personnel are not at health risk

when water columns are exposed, electric water-level probe and manual data entry may be

used.

• For larger numbers of wells where personnel time would be inordinately devoted to waterlevel measurements, instrumented airline or automated water level recording via transducers

is recommended.

For conditions where exposure to vapors off-gassing from well fluids poses an inhalation hazard,

instrumented airline or automated water-level recording via transducers is recommended. Several

approaches to water-level measurement are possible, each with its advantages and disadvantages. Table 2-

3 summarizes these features.

(2) For flow measurements, each pumping well and receiving well or discharge should be

metered. Total system pumping production should match total discharge. Imbalances may indicate leaks

or metering inaccuracies.

(a) Flow meters should be sized to the expected flow. Instantaneous and totalized flow readings in

commonly used volume-rate units (cubic meters/hour, gal/min, etc.) are necessary.

(b) Flow measurement method selections should take into consideration the quality of the fluid to

be measured. High-solids, biofouling, or scaling water streams may foul turbine flow meters (TM 5-813-

5, TI 814-3). Acoustic devices may have better service lives under some circumstances. Systems standard

to industrial waste water treatment applications should suffice.

(c) At a minimum, measurements should be taken manually daily to weekly, depending upon

fluctuation.

(d) Wherever possible, flow meters should have automatic readouts, either to a central SCADA

system or readout device. Systems standard to industrial water supply should suffice. Calibrate the

equipment at the frequency recommended by the manufacturer.

(3) For pressure measurement, either manually read or digital read-out meters may be used. With

both, plugging of sensor orifices is to be expected. To detect pressure changes in the conveyance system,

pressure should be measured as near as possible to the wellhead (immediately downstream of the pump

discharge check valve). Measurements should be taken daily to weekly. Automation facilitates data

collection.

(4) For electrical (power), measure changes in pump motor amperage (A) draw, circuit voltage

(V), and resistance ohms (Ω) to detect problems in the electrical system. Portable equipment should be

available for testing purposes.

(a) Voltage should be within +10 percent of the motor nameplate voltage when the motor is under

load (running). Larger voltage variations may cause winding damage. These variations should be

corrected in the power supply or the motor replaced to match the supplied voltage characteristics if the

voltage remains constantly high or low.
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Table 2-3. Features of Water-Level Measurement Methods

Type of water-level

measurement

Advantages Disadvantages

Electric sounder Commonly available, reliable

when maintained, accurate under

most water-only conditions (+0.02

in.), not highly subject to

downhole fouling. One sounder

can be used on multiple wells.

Requires wellhead access and unobstructed water

surface access, probe will foul in floating material

on water surface, mechanical aging of conductor

wire must be considered, cross-contamination is

possible, requires personnel to take levels and

manually enter data.

Airline (gauge

measurement) or

instrument

measurement)

Inexpensive, no need for direct

access to water level surface, each

well has a dedicated airline.

Relatively inaccurate (+1 in. or more), subject to

fouling, requires personnel for taking levels and

manual entry of data.

Airline (instrument

measurement)

Inexpensive, no need for direct

access to water level surface, each

well has a dedicated airline. With

instrument, improves accuracy to

electric water-level sounder range.

Data recording possible.

Subject to fouling, requires personnel for taking

levels.

Water level

transducers

Relatively accurate when properly

selected and maintained, permits

automatic data querying in

SCADA* system, dedicated to

well, no personnel exposure to

water, no direct water access

needed.

Relatively expensive per unit, requires regular

maintenance to deter fouling. If maintenance not

performed, automatic systems may record

inaccurate (useless) data.

* Supervisory, control, and data acquisition. Note that all these water level monitoring methods provide data that

can be manually entered into SCADA databases. Note that all conventional water level measurement systems are

fouled by non-aqueous-phase liquids and will yield inaccurate results.

(b) Increases in amperage on start or run cycles over listed service factor amps indicate

• Loose terminals in the control box or possible cable defect.

• Too high or low service voltage.

• Motor windings are shorted.

• Mechanical resistance such as sand in bearings.

(c) A drop in typical “run” amperage indicates a loss of mechanical resistance against motor

operation. This datum, in combination with reduced flow and/or pressure data, can be used to confirm that

a problem has developed in pump output, such as if a hole has developed in the pump discharge pipe.

(d) Deviations in circuit ohms indicate wiring problems. Low values on one or more line legs

indicates a potential motor short. Greater-than-normal values indicate poor cable connections or joints, or

windings or cables may be open. If some values are higher than normal and others lower than normal,

drop leads may be mixed.

(e) Megaohm detections outside the circuit indicate ground faults. For a motor installed in a well,

if resistance between any wire lead and true ground is <0.5 MΩ, motor damage is likely to have occurred.

(f) Voltage imbalance in three-phase (3-φ) systems causes excessive motor aging and poor

performance, and should also be checked routinely.
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(g) Total kilowatt-hour (kWh) use can be used to calculate changes in motor and system

efficiency.

(h) Electrical monitoring should be automatic if at all possible or, if manual, checked weekly.

CEGS 13405 provides guidance in specifying apparatus for monitoring pump motor operation as well as

the flow, temperature, pressure, and chemical-physical properties of the discharge. Particular attention

should be paid to regularly monitoring wellhead voltage, amperage, Ω, and φ balance conditions of

individual wells. Grounding should also be checked on a routine O&M schedule.

(5) For water sampling, strategically placed water sampling ports permit analysis of maintenancerelated water quality parameters. A monthly to quarterly schedule is recommended (Section 5-1 to 5-3).

Noncorrodible taps placed to permit sampling fluid at well discharge and other strategic points are

necessary to detect indicators of chemical and biological clogging and corroding conditions. Where

corrosion and biofouling are sampled directly using coupons (Smith 1992; McLaughlan 1996; Little,

Wagner and Mansfield 1997), provision must be made for attachment of the necessary sampling devices

and discharge of flow-through fluids. (Note: After any manual measurement or sampling, the location of

the automatic lwl shut-off should be checked to verify that it was not adversely affected.)

(6) Measuring systems should be automated as much as possible. Measuring system maintenance

must be integral with the well maintenance plan (Chapter 5).

2-8. Ground Water Geochemistry: Hazardous and Nonhazardous

a. Physicochemical data purpose. Physicochemical parameters are necessary to specify well

materials, predict clogging and corrosive conditions, and plot environmental change. These parameters

should be collected in the planning phase and during operation.

b. Physicochemical data analyses to be conducted.

(1) The basic, nonhazardous water chemistry data should begin with a standard set of constituents

known as the “routine analysis for water quality” (Domenico and Schwartz 1990). This set of constituents

is generally used for assessing the suitability of a water for human consumption and agricultural and

industrial uses. The routine analysis includes the majority of the mass dissolved in the sample and that

which remains unidentified is negligible. The routine analysis will also include other items, for example,

pH, Eh (ORP or redox potential), and total dissolved solids (TDS). This analysis should enable one to

identify the major ion species present, and the potential for deposition of solids.

(2) The routine analysis contains most of the major and minor ionic constituents, as well as a few

of the minor constituents, if needed.

(3) Computer applications are available for organizing and plotting ionic constituent data that

would facilitate tracking spatial or temporal variations in water quality (for example, HydroChem

available from RockWare). Analyzing the chemistry data can be facilitated by utilizing programs such as

WATEQ (Truesdell and Jones 1974), BALANCE (Parkhurst et al., 1982), and MINTEQ (U.S. EPA).
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(4) Table 2-4 summarizes the purposes of specific physicochemical analyses recommended for

use in identifying the mechanisms at work in ground water within the influence of the sampled wells.

Analysis of geochemical mechanisms at work is crucial information in “triage” (Chapter 5) in which a

determination is made of the appropriate levels of maintenance monitoring should be made. As specific

redox-sensitive pairs important to a system are identified, these pairs can be monitored for change over

time.

Table 2-4. Summary of Physicochemical Methods Relevant to Well Maintenance

Constituent Analysis Purpose of Analysis

Fe (total, Fe2+/Fe3+, Fe minerals and complexes) Indications of clogging potential, presence of

biofouling, Eh shifts. Fe transformations are the

most common among redox-sensitive metals in

the environment.

Mn (total, Mn4+/Mn2+, minerals and complexes) Indications of clogging potential, presence of

biofouling, Eh shifts. Less common but locally

important in some wellfields.

S (total, S2-/S0/SO4

2-, S minerals and complexes) Indications of corrosion and clogging potential,

presence of biofouling, Eh shifts.

Eh (redox potential) Direct indication of probable metallic ion states,

microbial activity. Usually bulk Eh, which is a

composite of microenvironments.

PH Indication of acidity/basicity and likelihood of

corrosion and/or mineral encrustation. Combined

with Eh to determine likely metallic mineral states

present.

Conductivity Indication of TDS content and a component of

corrosivity assessment.

Major ions Carbonate minerals, F, Ca, Mg, Na, Cl determine

the types of encrusting minerals that may be

present and are used in saturation indices. One

surrogate for many cations is total hardness.

Turbidity Indication of suspended particles content, suitable

for assessment of relative changes indicating

changes in particle pumping or biofouling.

Sand/silt content (v/v, w/v) Indication of success of

development/redevelopment, potential for

abrasion and clogging.

Note: Generally, the Fe2+/Fe3+ ratio (easily measured using conventional field analysis instruments) is

the most useful. In some settings, Mn oxidation (resulting in more difficult-to-remove minerals) and

the sulfur system may be dominant.

c. Hazardous physical/chemical parameters. Personnel safety (Chapter 7) dictates that physical

(primarily radiological) and chemical conditions that will affect how maintenance can be performed

should be known. For the most part, data collected for the purpose of regulatory monitoring (and its

toxicological interpretation) should cover hazards of exposure to pumped fluids. Additional factors may

include:
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• Radon emission (hazard of exposure during long-term monitoring).

• Carbon dioxide, volatile organic gases, and hydrogen sulfide (hazard during confined space

entry or long-term exposure).

d. Compatibility with well cleaning chemicals.

(1) Chemicals that may be used in maintenance treatment of wells (Chapter 6) may react

unfavorably with pumped fluids to produce

• A hazardous personnel condition.

• Unexpected system damage.

(2) Potential reactions should determined prior to chemical application. Table 2-5 provides

representative incompatibility relationships with compounds used in well treatment.

Table 2-5. Well Treatment Chemical Incompatibility

Chemical Chemical Incompatibility

Acetic acid Chromic acid, ethylene glycol, nitric acid, hydroxyl compounds, perchloric

acid, peroxides, permanganates, and other strong oxidizers.

Acids (in general) Sulfides, cyanide compounds, chlorates and perchlorates, ammonium nitrate,

azides, alkali and alkaline earth metals, organic peroxides.

Carbon dioxide Dusts of aluminum, manganese, titanium, chromium, and maganese suspended

in carbon dioxide streams.

Chlorine Anhydrous ammonia, ammonia, acetylene, butadiene, hydrocarbons,

hydrogen, sodium carbide, turpentine, benzene, finely divided metals,

activated carbon, any strong reducing compounds.

Chlorine dioxide Organic materials, ammonia, methane, phosphine, hydrogen sulfide.

Halogens in general:

(Strong oxidants)

Fuels, any flammable liquid, or other organic compounds.

Hydrofluoric acid Aqueous or anhydrous ammonia, intensely corrosive to organics.

 Hydrogen peroxide

(Strong oxidant)

Copper, chromium, iron, most metals or their salts, alcohols, aniline, acetone,

organic materials in general.

Hypochlorites Acids (specifically HCl), activated carbon, other concentrated organic

compounds, anhydrous ammonia.

Nitric acid (conc.) Acetic acid, acetone, aniline, chromic acid, hydrocyanic acid, hydrogen

sulfide, flammable liquids, flammable gases

Organic acids Aluminum, arsenic compounds, strong reducing compounds.

Oxalic acid Silver, mercury (forms low-solubility minerals in presence of calcium).

Potassium

permanganate

(Strong oxidant)

(Strong oxidant) glycerin, ethylene glycol, benzaldehyde, sulfuric acid, fuels,

other organic compounds, flammable and explosive compounds.

(2) Persons designing any treatment involving fluids that contain strongly reactive, oxidative,

reductive, explosive, or volatile compounds should specifically review chemical reactivity databases for

conflicts. EM 385-1-1 provides guidance in health and safety physical/chemical reporting needs for health

and safety.
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2-9. Biological Assay

a. Purpose. Biofouling is historically a major or dominant component of corrosion and clogging

impacts on ground water remediation systems (Leach et al. 1991; Smith 1995; Alford and Cullimore

1999). Section 4-6 reviews potential effects of system biological activity.

(1) From a maintenance standpoint, it is well recognized that early detection is crucial to the

management of biofouling problems. However, it has always been difficult to correlate the results of

testing for biofouling components and the degree of deterioration of components of wells. For example,

samples that do not contain biofilm particulate matter and microorganisms do not necessarily indicate an

absence of this material. Cultivating media may not support microorganisms that contribute to fouling,

and sampling may not collect samples representative of the formation's and well system's microbial

ecology.

(2) Smith (1992), Cullimore (1993), Smith (1996), and Alford and Cullimore (1999) discuss and

provide guidance on biofouling assay methods and their utility in maintenance monitoring to provide

useful information. With such information, the following questions can be readily answered:

• Is biofouling present?

• What types of biofouling organisms are present?

• Is the well more or less biofouled than before? The answer to this last question requires

monitoring over time.

b. Mission of biological tests. Biological assay plans have differing strategies depending on the

purpose of the study. Biological assays for maintenance monitoring have goals different from those for

general aquifer ecology or bioremediation planning. Maintenance monitoring methods chosen should be

task-oriented to detect those biological indicators or conditions that lead to reduced well system

performance. For this reason, methods that provide rapid, general insight into biofouling and biocorrosive

conditions are preferred over methods that characterize genetic makeup or metabolic capabilities.

c. Types of biological analyses employed in PM monitoring.

(1) Examination by light microscopy. This has traditionally been the method of choice for

confirming and identifying "iron bacteria" (APHA, AWWA, and WEF, 1998, Section 9240). However, in

many instances, biofouling as a cause of well problems may be difficult to diagnose via microscopy

alone, even with very good tools and skills (Smith, 1996).

(2) Cultural enrichment.

(a) Culturing can provide a means to detect nonfilamentous, metabolically active biofouling

microflora, and also to profile the ecological physiology niches occupied by microorganisms. Currently,

the most promising cultural approach, from a practical application standpoint in the United.States., for

routine maintenance monitoring purposes available in North America is the Biological Activity Reaction

Test (BART) method (Cullimore 1993). This method was found by Smith (1992) in field trials to provide

useful qualitative information in well biofouling events and is increasingly accepted as a standard

biofouling monitoring method (Smith 1996).

(b) The BART method tubes come with a variety of media mixtures. The IRB-BARTTM0 , for

example, is designed to recover anaerobic (sulfur- and nitrate-reducing) and microaerophilic heterotrophic

Fe- and Mn-precipitating microorganisms (iron-related bacteria, IRB). Cullimore (1993), Smith (1992,
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1996), and Alford and Cullimore (1999) provide guidance in BART method use. Smith (1996) is a

proposed standard method, incorporating BART-type methods to replace the current (Section 9240 and

ASTM D 932) standard methods that rely on microscopy alone. MAG tests (MAG Ltda., La Plata,

Argentina) are a commercial alternative to some versions of BART (Gariboglio and Smith 1993; Smith

1996). In addition, bench-formulated liquid media may be used if preferred and facilities are available.

Kissane and Leach (1993) (Appendix C) and Smith (1992) provide guidance in the context of well

biofouling analysis. The commercial products eliminate the need to determine specific nutritional

requirements and the facilities typically needed for environmental microbiology, and thus are more likely

to be practical in maintenance monitoring use.

(3) Sampling issues.

(a) Cullimore (1993) describes a time-series pumped-sampling program that attempts to

overcome the uncertainties of collecting particulates (biofilm components) by grab sampling. Cullimore's

procedures involve taking advantage of the phenomenon that biofilm detachment occurs preferentially on

start-up after a period of rest, in which the pump is allowed to shut down for a period of time from 2 hr to

several days. This approach, which includes taking replicates of samples at each sample event, helps to

overcome the statistical limitations of pumped grab sampling for cultural analysis.

(b) Grab samples remain unreliable for microscopic analysis (Smith 1992; Tuhela, Smith,

Tuovinen 1993). For this purpose, some method is needed to provide enough sample to view or otherwise

analyze mineralogically or chemically. Methods for collection of biofilm on immersed surfaces can

provide essentially intact biofilms for analysis. These methods are also adaptable for collection of

samples of inorganic encrustations and evaluating MIC effects (McLaughlan 1996; Little, Wagner, and

Mansfield 1997). The flow cell system in Smith (1992) has been successful in practical use for such

biofilm collecting. Sample collection using this method will be described in the Standard Methods 20thEdition Supplement, Section 9240. Coupon sampling apparatus developed for MIC evaluation may also

be used.

d. Minimum biological testing elements. At a minimum, a maintenance monitoring program for

HTRW pumping and injection wells should include the use of tests kits (BART) and other selfmonitoring systems (biofilm collection and visual inspection of components) on site, and visual

inspection of equipment, at the least in a troubleshooting or baseline-monitoring role. Sample collection

should follow the procedures of Cullimore (1993) for BART grab sample collection. Biofilm collection

(either as a specific task or part of equipment inspection) can follow the protocol outlined in Smith

(1996). BART testing and biofilm collecting can be conducted in a baseline troubleshooting role and then

annually or at observed changes. Baseline-scheduled BART and other biofouling analyses are a useful

part of “triage” (Chapter 5) for establishing maintenance protocols for new systems and documenting

changes during operation when samples are collected regularly. Some sites may exhibit little or no change

in biofouling analysis results once well systems are established and other sites may provide chronically

aggressive results, so that BART analyses can be discontinued once the condition is documented. In these

sites, biofouling analysis can be minimized.

2-10. Field Data Reporting and File Documentation

a. Purpose. The primary purpose for collecting, analyzing, and tracking trends in collected data is

that there are many reasons why a well may experience diminished performance, and collected data are

crucial for identifying causes. Also, once a pattern of well performance decline is established, collected

data will enable the operators to plan maintenance and rehabilitation activities before a well is beyond

recall.
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b. Well data file features. Each well requires a comprehensive file of all data pertaining to its

ongoing maintenance and performance history as well as the initial data pertaining to its construction,

well performance, pump performance, water chemistry, and biological environment described above.

Establishing this record system for each well should be done at the onset of the project. Since such data

will periodically be manipulated and analyzed, a format for the records should be established that is

compatible with the methods used for analysis. Consistency will save time and frustration, and improve

accuracy.

c. File records purpose and format issues. Correct and relevant field data recording is essential

for data to be of any value. How this is done can be project specific. HTRW projects, which are under

regulatory supervision, by nature have in place systems to acquire, store, manage and report data sets. The

data management system in place for the project in question can be adapted to provide the same activities

for maintenance planning. Format issues include:

• Successful maintenance monitoring programs have been run using entirely physical paper

files in the water supply field.

• Spreadsheet organization of data provides a tabular display of various data, permits plugging

data into formulas to perform routine calculations such as those for specific capacity and

motor efficiency, and permits rapid charting of data trends.

• Database systems permit cross-comparison of parameters to ascertain cause-effect

relationships (e.g., changes in hydrocarbon concentration vs. head loss in pumping systems).

Storage and availability issues include:

• Copies of the spreadsheets should be kept on-site at the well field in individual log books for

each well.

• Essential well data (depth, diameter, pump type, and identification) should be marked at the

well.

• Accessible inventories of physical file components such as video tapes should be maintained

so that people reviewing files may know what data are available. Chapter 8 provides

checklists, and other chapter topics indicate data needs. These should be reviewed.

d. Types of records needed. Essential information includes:

(1) Physical locations and as-built descriptions of the wells and their equipment. The physical

geographic location of each well should include reference to fixed landmarks as well as precise

geographical coordinates such as provided by a geographical positioning system (GPS) for use in plotting

using geographical information systems (GIS).

(2) As-built diagram of the well's construction, with any modifications over time.

(3) Lithologic log of the well as constructed, well drilling and construction logs, and any other

logging data (caliper, gamma-gamma, etc.). Logs must be completely labeled with dates, depths, and

borehole site identification. Copies of interpretation reports should be included in the file.

(4) Records of pumping tests and geophysical structure, borehole flow meter, etc., tests of the

completed well over time.
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(5) Pump performance data from pumping tests as applicable by date, including analysis and

recommendations of pump performance reports.

(6) Pumping and static water levels by date and time of day.

(7) Dates of replacement of components, manufacturer and type of component, if known, and

length of service, if known. Itemized invoices with costs should be included. Photos or video tapes should

be made of deteriorated components for future reference, including descriptions. Copies of product owner

operation and service literature should be included along with documentation of any contractor service

personnel.

(8) Electrical, power and pump mechanical information.

(9) Water quality data from wellhead samples, plus biofilm collector results, listed by date. Labs

and costs should be tracked, and should include reports analyzing water quality data.

(10) Electrical, power and pump mechanical (submittal literature, shop drawings, and nameplate)

information.

(11) Details of well rehabilitation activities, including dates, diagnosis, if any, treatment methods,

results, time involved, and costs.

(12) Color borehole TV survey videotapes. These should be taken at any zero point such as at

well construction and at intrusive service intervals such as well rehabilitation to record visual changes in

well conditions. Tapes may be consolidated as summary tapes of important well features over the years.

Tapes should be labeled by well identification and date and stored properly in an accessible location.
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Chapter 3

Historical Data: Influence on Pumping/Injection and Drawdown Results

3-1. General

a. Purpose. The primary purpose of routine maintenance monitoring data acquisition is to provide

information to chart trends in historical well and system performance. These changes over time indicate

performance change, and trends are used to schedule maintenance activities. A checklist is provided in

Chapter 8 for use in assessing the adequacy of well maintenance actions.

b. Key factors. The key factors in maintenance monitoring analyses are not the absolute numerical

values (e.g., total Fe = 2.6), but the changes over time (total Fe was 2.6, 6 months later it was 0.6). A

significant change in parameters indicates that the well may be in need of attention, or indicates

biogeochemical changes of interest as microorganisms extract Fe, PO4, etc., which may eventually lead to

well performance changes. In any system or activity, data may be collected to fulfill some past directive,

but the purpose for the activity may be lost over time as personnel change. Personnel involved in well

maintenance should be conversant with all of the following sections.

3-2. Pumping Rates

The typical pumps used on HTRW projects are the widespread centrifugal pump designs adapted for well

applications. In centrifugal pumps, output flow is in a dynamic relationship with system head: as system

head is raised and lowered (e.g., due to clogging or other system hydraulic fluctuations), flow lowers or

rises in inverse proportion. Changes in pumping rates over time will result due to changes in pumping

head.

a. Internal pump changes. Clogging (increased resistance) and wear (reduced pressure) both

result in lowered pump output, usually as a gradual declining trend. In submersible or lineshaft turbine

well pumps, an abrupt loss of output usually is due to a hole developing in discharge piping. Another

cause may be an inadvertent valve closing or other obstruction.

b. External head changes. If regional or pumping/injection head changes, this change will affect

the pump output of an otherwise properly functioning pump. While direct measurement of water level

(Section 3-4) is a more sensitive parameter, increased drawdown may be reflected in reduced flow. The

size of this effect is specific to the pump.

c. System demand changes. Operational changes may affect the flow and efficiency of a pump.

Restricting flow (e.g., for plume management) may be reflected in a pump operating inefficiently and

having a shortened operating life.

3-3. Wellhead Pressure

Wellhead (system) pressure in the pump discharge significantly affects pump output flow (Section 3-2)

and likewise affects injection acceptance. If system head increases, a centrifugal pump cannot produce as

much output. Reduced flow then also may be a reflection of increased system head. This in turn is most

typically a result of clogging activity. However, other causes, such as inadvertent valve closing or

insufficient power, should also be investigated.
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3-4. Water-Level Data

a. General use of water-level data. Water-level data, combined with flow data, can be used to chart

changes in well specific capacity (and aquifer and well loss) over time. The longer and more

representative the water-level history, the more reliable the trends that can be drawn from the data.

b. Internal pumping/recharge well levels. Except when static, these levels only reliably reflect the

dynamics inside the well itself. Pumping output flow divided by the pumping (or injection) dynamic level

provides specific capacity (Section 2-2). This calculation should also be made over time. As with the

source data, the longer and more representative (seasonal, site pumping pattern) the specific capacity

history, the more likely that valid trends can be drawn.

c. Comparisons of water levels. Pumping/injection water levels in wells typically differ

(sometimes dramatically) from levels outside the casing. For direct comparison with aquifer loss and well

loss calculations (Section 2-2) and routine monitoring, these differences can be used to narrow down

• Whether a change in pumping water level reflects a "regional" (site) trend.

• Where clogs are occurring.

(1) Pumping or injection dynamic level to filter pack piezometer comparisons are used to

determine whether or not clogging is in the screen and filter pack. Installation of in-screen and satellite

rehabilitation wells facilitates this monitoring (Section 5.4 and Alford and Cullimore 1999).

(2) Pumping or injection dynamic level to area monitoring well comparisons are used to

determine if clogging is occurring in the screen and filter pack vicinity, or whether a change in pumping

water reflects change at the "regional" scale.

(3) Unit-specific piezometer levels are used to determine what changes are occurring in the

contributions by multiple units to a well.

3-5. Piezometric Data

Piezometric data provide water levels outside the immediate casing and pumping influence of a well.

Piezometers (water-level monitoring wells) offer information on the response of a producing or accepting

unit to change induced by site activities in addition to larger scale effects (e.g., changes in water table). As

with pumping and recharge wells, the reliability of water-level response in monitoring wells depends on

the wells’ original design, development, and maintenance. A Standard Guide to procedures for this

purpose has been published by ASTM (D 5978).

3-6. Electrical (Power) Data

Power component (V, A, φ) data (Section 2-7) charted over time provide a history of motor and power

system changes. Historically, power problems may be the most common source of well problems. Power

supply consistency is sometimes suspect, especially with φ imbalance. A history of φ imbalance data can

provide the evidence needed to take well system power source problems to the power supply for

correction.

a. Off-grid power quality. On generator- or solar-run systems, V and A changes reflect variability

of the quality of power supplied and can provide ideas on what changes may be necessary.
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b. Use of power data. Within a pump circuit, changes in amperage draw can be used to spot worn

motors, or pumping system problems such as a clogged or perforated discharge line. As with the

hydrologic data, the longer and more complete the records, the more likely that valid trends can be

charted.

3-7. Video for Historical Comparison

When properly used, downhole video provides a direct view of conditions within wells. Video documents

the as-built condition and timing of subsequent well damage and deterioration. Types of clogging

conditions can be identified visually with some background. A progression of videos in any particular

well, especially from the original construction condition, provides a direct way to watch changing

conditions in the well (e.g., progressing screen corrosion or biofouling development). A video can also be

used for comparison to file records where file records are suspect or incomplete.

3-8. Piezometric Maps

Existing interpretation aids available on typical HTRW projects can be used to assist in performance

analysis. Piezometric or water table maps provide information on "regional" head data that influence

specific capacity, and help to illustrate anomalies around pumping wells. Depths of water-bearing

formation exposure and evidence of pumping centers can also provide insight into well-clogging

oxidation occurrence in a well field.

3-9. Geologic Regime

a. Information on geologic maps. Geologic maps and cross-sections provide information on the

influence of stratification and particle and geochemical types on well performance and degradation, and

how effective original well designs were. Trouble-causing situations such as long, large-particle-size filter

packs in variable stratified aquifers can be identified. Expected well treatment problems such as

overdeveloping clay lenses can be predicted. Good geology and geophysical data relevant to the well's

location are essential for proper well design.

b. Problems with too little geologic information. Well systems are often designed based on too

little geologic site information. Problems that crop up often have a basis in a well being designed for a

generic site condition, sometimes based on single borings, instead of well-site specific data. Files reveal

when this is the case when multiple wells on a site will have identical depths, screen slot sizes, and filter

packs. Results include screens and filter packs that are too fine or too coarse for the formation material

and generally poor hydraulic efficiency.

c. Preserving original information. Because interpretations of geologic data over time may be

distorted or simplified, it is recommended that original field notes be preserved for reference. Good data

collection and analysis save operational money in the long term by aiding good well design that improves

the capability of facility operators to maintain well systems. It is important that facilities maintain an

archive that remains available and accessible despite management changes for use by future technical

oversight or advising personnel (Section 4-3).

3-10. Maintenance Logs for Individual Wells

a. File elements. Section 2-10 reviews major file elements for well system maintenance. While

general site information such as piezometric maps can be held centrally, files should be kept for

individual wells to record their specific O&M histories.
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b. Information recorded at well site. As an onsite backup, brief basic information on the well

should be kept within the casing or casing protection sleeve or structure. This information should include:

• Dimensions of the entire well (depth), casing (length) and screen (length, location, type, and

slot sizes), and filter pack (length, thickness, and particle sieve sizes).

• Material construction of each.

• Pump and power information.

• Information on any inserts downhole.

• Last service date and information on how to obtain more detailed records.

c. Offsite backup information. Files and video tapes kept at the project site should be duplicated at

an offsite location that will continue to be available to site O&M personnel perpetually, regardless of

changes in project management or service provider firms.

3-11. Downtime History

a. Information from well files. Well files should include a brief comment section on history of the

total (project site) system for use in pinpointing causes and effects. Service intervals, costs, details of

persons and companies involved, and analyses of results (what works, what doesn't, specific capacity

changes) should be included for a history analysis, and for the sake of the next person (perhaps years in

the future and unacquainted with the last service action).

b. Out-of-operation information. It is sometimes most useful to know why and how long a well

was out of operation. For example:

(1) It is commonly the case on HTRW remediation sites to construct wells and then to leave them

sitting idle for long periods during project development. It is widely observed that this practice results in

wells that must be rehabilitated before they can be used (Borch, Smith, and Noble 1993; Smith 1995;

NGWA 1998).

(2) Sites and individual wells may experience periods of hiatus in operations for various reasons.

Again, equipped, developed wells, perhaps already with developing degrading conditions, sit idle.

(3) Such information can help personnel in troubleshooting problems down the line to make sense

of the condition they find. Checklists for site well array O&M planning are provided in Chapter 8.
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Chapter 4

Data Evaluations and Troubleshooting in Well System Maintenance

Making and refining maintenance decisions and evaluating the degree of maintenance action success

requires a systematic and effective data evaluation and troubleshooting process. Organizing such a

process requires both institutional and technical planning.

4-1. Institutional and Funding Issues in Maintenance Planning, Analysis and

Execution

a. Historic lack of well O&M planning. Successful O&M of any mechanical system such as a

pumping well array requires an institutional structure and indoctrination that preventive maintenance is

valuable and indeed essential in preventing future problems. This is well demonstrated for wells in a

variety of operating settings (including water supply, dewatering, and hydraulic relief) and particularly

well demonstrated in HTRW remediation. Despite the well-known vulnerability of monitoring and

remediation wells to performance degradation, provisions for preventive design and maintenance are

routinely shortchanged in practice (e.g., Smith 1995; Alford and Cullimore 1999).

b. Institutional and contractual barriers to well O&M implementation. A persistent problem in

encouraging rational well maintenance planning and execution is the array of roadblocks that discourage

the implementation of these logical behaviors in the HTRW remediation field. In the project

development-contract administration process, USACE internal professionals or a contracted architecturalengineering (AE) firm develops a scope of work (SOW), specifications, and design. Once a contract is let,

the work is administered by Construction teams. It is imperative that well system O&M be explicitly

incorporated into the SOW and specifications, and included as an issue in design (designing for ease of

maintenance). Likewise, contract administration needs to enforce the well system O&M imperatives of

the SOW.

(1) History and experience (e.g., Smith 1995; Alford and Cullimore 1999) demonstrate the

necessity of planning and adequately funding well system O&M oversight and professional review. Such

funding and O&M planning (with professional review):

• Should be an integral part of Title II HTRW remediation planning and funding activities at

the outset of project development, and should be included in any specifications or SOWs

involving the monitoring and pumping of ground water.

• Should be part of the USACE review checklist.

• Should include maintenance monitoring data management as an integral part of site data

management.

• Should ensure that, once constructed and active, HTRW remediation projects have the

funding budgeted and available to perform adequate routine well system maintenance

monitoring, repair, replacement, and cleaning as part of the overall site and system O&M

contract.

• Should be protected to the extent possible contractually from transfer to other purposes.

(2) Checklists for well system O&M maintenance planning are addressed in Chapter 8 and

examples provided in Appendix D.

c. Expected outcomes of a lack of maintenance planning. The logical necessity of such planning

takes the form of a typically remorseless "pay me now or pay me later" scenario:
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4-2

(1) Filter and other water treatment clogging occur due to constituents pumped from wells that

supply the treatment plants. Some of this is unavoidable, but others, such as biofouling buildup, can be

minimized by preventive maintenance actions at the well source.

(2) Hydraulic losses due to clogging occur that can be prevented and mitigated in the same way

by maintenance activities at the well source and preventive engineering design that reduces choke points

and permits line service.

(3) Perhaps most costly of all is a situation where the project's objectives (ground water cleanup)

are not achieved or delayed due to preventable well field problems.

d. The extent of O&M monitoring must be determined. Chapter 2 reviews testing recommended

and minimum data elements needed to define conditions that could cause well system clogging and

corrosion. Chapter 3 defines the historical background needed to establish trends. Once a baseline of

information on site hydrogeology, biogeochemistry, and operations is established, and trends become

apparent through scheduled monitoring (Chapter 5), the level of effort appropriate to detect deteriorating

conditions can be established.

4-2. Quarterly Review of Site Performance Data

a. Schedule of performance review. At a minimum, projects should review performance and other

maintenance monitoring data (Chapter 2) regularly. Doing so quarterly is a common recommendation and

fits into typical project review schedules. At this time project's operational team reviews data and

operational information to answer the questions: "Where do we stand now?" and "What do we expect to

happen?"

b. Personnel versatility. A review of the range of information required for baseline well field

maintenance monitoring (Chapter 2) shows that it is multidisciplinary. It is highly recommended that the

project involve personnel experienced in well field maintenance information review and interpretation.

Such persons (or a team of persons) should be conversant with all of the following sections. Desirable

qualifications of personnel should be incorporated in bid specifications if O&M contractors are to be

expected to comply with them.

4-3. Baseline and Historical Data for Wells/Site

a. Background. Chapters 2 and 3 outline necessary baseline and historical well and site

information and how it should be managed to facilitate O&M planning. A crucial element is the

availability of historical information and the means to interpret that information. If possible, information

should be available extending back to site characterization studies and forward to the present to aid in

evaluation of processes and activities affecting the maintenance of the well system. O&M personnel can

predict trends based on data gathered during troubleshooting, but uncertainty is higher than with actual

historical data.

b. Historical data management. An essential element in this process is a data management system

that permits the detailed tabulation, plotting, cross-reference, and statistical analysis of a broad range of

information as described in Section 2-10. A system that stores and permits the easy retrieval and crossreferencing of a variety of information without artificial topical boundaries helps human troubleshooters

and planners to see patterns that may not be immediately obvious. This archive may be physical and the

retrieval system a knowledgeable human, or on a computer. Project data systems should permit:
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4-3

• Charting of information (e.g., pumping water levels) back to the site's characterization and

development at flexible scales.

• Cross-referencing of various data to look for trends (e.g., specific capacity vs. lithology or

biofouling indicators).

• Data access by (or to be maintained by) the department or firm responsible for O&M if these

tasks are split from regulatory oversight.

c. Human operational experience and its preservation and transfer. As useful as data and other

information are, they are most valuable when filtered through human operational experience. All systems

have quirks or features that defy the kind of quantification possible in a computer database file.

(1) Filing systems are imperfect and incomplete. Human experience provides the kind of

anecdotal background that is often most useful in troubleshooting. For example, noting that problems

began when there was a change in pumps.

(2) HTRW remediation site maintenance planning should make provision for:

• Regular recording of maintenance actions and observations by operating personnel.

• Minimizing personnel changes to preserve memories.

• Ensuring that key operating personnel are well-informed and trained in their tasks.

• Outside expert assistance on an as-needed basis.

4-4. Operator/Working Crew Leader Qualifications and Training

Well-trained and motivated onsite operating personnel are crucial in successful O&M management.

Frequent turnover, poor training, and lack of positive motivation will defeat even the most well-crafted

O&M plan. While requirements may vary, the following are essential:

a. Institutional continuity and "ownership" of the O&M plan and its execution are crucial in

fulfilling any plans to properly maintain well arrays. Experience shows that if maintenance is the personal

crusade of one person, but not adopted by the entire site operator crew and management, that crusade

ends if the original enthusiast leaves.

b. The operators on site must understand the O&M plan, the purpose of its activities, and why

they are important to the operation of the remediation system. At a minimum, the operations supervisor

should understand and be able to verify field data collection, manage and participate with field personnel

in daily maintenance actions, and enforce common sense issues during daily operation.

c. For these reasons, training is essential. All personnel responsible for well array O&M should be

formally trained in the O&M plan, its components that pertain to the well system, and essential tasks

(Chapters 2 and 3).

4-5. Determination of Operational Maintenance Responsibilities

An important consideration in well system O&M is defining the roles of plant management and

operational personnel in scheduling, analyzing, reviewing, and revising various O&M activities. These

can be divided into two primary levels.
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a. Plant manager -- project level. This person or team operates at the level of the HTRW

remediation project's management level and integrates O&M activities into the overall project goals and

structure. Primary tasks related to well system O&M:

• Sets up maintenance action schedules

• Follows up to ensure actions are accomplished

• Is responsible for data collection and evaluation

• Prepares status report of evaluations

• Seeks and works with outside expert help as needed.

b. Designated oversight personnel -- operations level. This person or group operates at the

HTRW remediation site level. If a separate O&M Company oversees the regular function of the site's

physical plant, then this group may consist of both the O&M company's management and onsite

personnel. Their work scopes involve:

• Assisting in maintenance schedules and making recommendations for modifications based on

site-level experience with individual wells.

• Conducting necessary training of pertinent personnel (as necessary with outside expert

assistance).

• Being responsible for enforcing maintenance actions and reporting to the plant manager.

4-6. Biological Activity Implications

a. Biological activity importance to O&M. Section 2-9 reviews biological maintenance

monitoring needs. However, HTRW remediation projects are typically designed by personnel

(environmental engineers and hydrogeologists) who typically have a limited background in microbiology.

It is important to understand the purposes for the emphasis on bioassay in maintenance monitoring for it

to be properly implemented.

(1) Production and hydraulic efficiency loss. Historically, the primary factor in well system

production loss on HTRW projects is biological activity (e.g., Leach et al. 1991; Smith 1995; Alford and

Cullimore 1999; ASTM D 5978). Biofouling has been identified as a primary cause of well performance

problems in "clean" water supply for many years (e.g., Borch, Smith, and Noble 1993; Cullimore 1993),

For ground water contaminant plumes, unless the predominant contaminant is biologically recalcitrant

(such as TCE, for example), microbial activity is greatly accelerated and increases the rate of biological

corrosion and clogging.

(2) Effects of "representativeness" of monitoring samples. Biofilms, which serve protection and

scavenging functions for microorganisms that form them, naturally have the effect of attaching and

holding organic molecules and some metals. Consequently, it has been recognized that monitoring well

samples may not always be representative of bulk-formation ground water quality (unpredictable

accuracy). Smith (1995;1996) reviews the limited literature on this subject relevant to monitoring. This

effect and its implications are recognized in ASTM D 5978.

(3) "Unexpected" geochemical changes. Biological activity has the tendency to induce or

accelerate processes that may be unlikely or much slower in an abiotic environment. For example,

biological corrosion occurs in environments considered "encrusting" in Langelier, Ryznar, or similar

indices (Borch, Smith, and Noble 1993). Iron and occasionally manganese clogging accelerates where

metal-precipitating bacteria flourish. Iron, manganese, and sulfur (S0

0 or SO4

2-

) reduction processes (all

entirely microbial) mobilize large amounts of iron, manganese or sulfide (S2-) into solution. The S2-
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4-5

readily combines with dissolved iron (Fe2+) to form encrusting iron sulfide minerals. Iron oxidation is also

driven anaerobically by denitrification. The CO2 generated by microbial respiration drives carbonate

equilibrium toward bicarbonate saturation. These and other microbial effects tend to complicate

geochemical estimating.

b. The importance of biological assays in maintenance monitoring. These assays provide:

• An "early warning" method of predicting biological effects on geochemical transformations

such as predicting ferrous sulfide mineral formation in a 12.9o

 C (55o F) alkaline carbonate

ground water when SRB are detected.

• Means of evaluating changes in biological activity over time. In this, the historic record is

essential.

c. Interpretation. At the present time, the interpretation of biological assay information is not

always straightforward. Because the existing assay tools are inexact, proper interpretation is critical (but

becoming easier). Because interpretation is somewhat subjective and changing over time (e.g., compare

Smith 1992; Cullimore 1993; and Smith 1996), it is useful to involve personnel experienced with this type

of testing in planning an O&M program and in forming the O&M management team (Section 4.5). The

references to literature and web site resources provided (Appendix A) offer a background in the types of

effects to expect.

4-7. Impacts on Plant

The scope of this document does not extend to treatment plant O&M; however, it has become evident that

bio-physical-chemical activity in wells (pumping and injection) has a direct influence on plant and project

mission performance. In addition to the routine effects of pumped water quality on the plant, the

consequences of changes induced by well treatments should also be considered. Treatment effects may

include extended periods of sloughing from the well as damaged clog components are dislodged and

pumped out. In general, treatment plant effects expected should include direct adverse effects on

treatment plant performance, input and output effects, and institutional loss of confidence.

a. Direct adverse effects on treatment plant performance. These effects include:

• Excessive organic loading ((biological oxygen demand (BOD), chemical oxygen demand

(COD), etc.)) of the plant.

• Acid solution pH shock, which may be particularly disruptive for activated carbon or

biological digestion systems (relying on attached microflora). These should be neutralized to

within stated plant tolerance.

• Process disruption due to increased BOD, COD, etc., of the development solution and

subsequent pumpage from wells re-establishing the biogeochemical status prior to the

treatment event.

• Low contaminant concentration due to plume disruption.

• Sediment production and geochemical alteration of constituents so that they are not as well

addressed by the treatment system. Clogging slugs of biofilm and solids (sand, silt, clay)

developed out of wells may be particularly destructive to membrane and resin bed treatment

systems.

• Fouling of piping, sensors, air strippers, granular activated carbon columns, ultraviolet

emission lamps, etc.

• Alteration of geochemistry. Rapid flip-flopping of pH can be expected during treatments.

Plants adapted to established reductive water may have to transiently adapt to a more
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4-6

oxidative Eh. Erratic detections or spikes of compounds whose solubility is redox- or pHsensitive may occur.

• Metal oxide breakthrough from filters into the rest of the treatment train. Acidic waters may

flush attached iron and other metal oxides from filter particle surfaces, and breakthrough may

occur, resulting in coating of downstream media and membranes.

• Enhanced cost of operation due to lowered efficiencies and frequent cleaning, backwashing,

or replacement of media.

b. Input and output effects. The effects include:

• Pumping well and system clogging, which restricts flow so that cleanup of calculated plume

volume is slowed or stopped, or contaminated ground water bypasses the installed system

while wells are replaced or rehabilitated.

• Altered aquifer hydraulic conductivity so that the plume bypasses the pumping well array,

favoring higher-hydraulic conductivity channels less affected by biofouling.

• If injection wells cannot take enough water, the plant has to cut back or shut down.

c. Institutional loss of confidence in pump-and-treat strategies. This effect is already apparent in

the literature and discussion groups when “pump and treat” is discussed. Arguably, a contributing factor

in poor performance in these systems is performance deterioration due to environmental factors such as

biofouling that can be addressed through well system PM (Smith 1995; Alford and Cullimore 1999).
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5-1

Chapter 5

Schedule of Maintenance Actions for Wells

5-1. Well and Plant Maintenance Schedule Overview

a. General. Chapter 9 provides a recommended maintenance program. This pamphlet provides

recommendations and decision trees for a variety of operational settings. It is emphasized that this is a

guide that should be adapted to local needs and should be revised as experience dictates.

b. Pre-selection of maintenance testing intervals and methods. There is considerable debate

concerning appropriate monitoring and inspection intervals for maintenance of pumping and injection

wells for HTRW sites. The purpose of such monitoring is to

Detect deterioration symptoms in time to permit the most cost-effective repair or replacement.

Define the condition sufficiently so that correct rehabilitation diagnosis and treatment are possible.

The ideal situation from an operational standpoint is to achieve these objectives with the minimum

possible intrusion, time, and material costs. Some biogeochemical environments and hydrologic conditions result in a reduced likelihood of well clogging and corrosion than others. Among those conditions so

recognized are high-specific-capacity aquifer settings under nitrate-reducing conditions with modest total

organic carbon. Clogging potential is greater at both higher and lower redox potentials (e.g., sulfatereducing and iron-oxidizing). Field work on domestic water supply wells in a region with well clogging

and water quality concerns documented in Cullimore and Legault (1997) showed that, if there is a

background of data on well-deteriorating causes and effects, monitoring can be limited to one or a few

biological parameters. These parameters can be supported by the hydrologic measurements previously

identified in Chapter 2. However, defining deteriorating conditions is necessary during site development

for monitoring to be safely minimized and can only be reasonably accomplished using existing wells in

the area that have had time for biofouling to develop.

5-2. Minimum and Optimal Regular Schedule for First Year

This section and Sections 5-3 and 5-4 offer maintenance schedule recommendations based on the

principle of establishing a data baseline and then settling into less frequent (or more intense) preventive

maintenance (PM) activity if conditions warrant. Table 5-1 is a summary minimum recommendation for

first-year maintenance activity frequency for an HTRW well array. It is an appropriate monitoring levelof-effort for a new (or newly started) facility if

• There is sufficient background information on the biogeochemical and hydrologic

environment to make good estimates of the types and rates of deterioration to be expected.

• The well construction and system equipment are well documented (as in a new system) and

not one taken over from another responsible party or O&M service provider).

a. Choosing level of effort. “Sufficient” information may include experience with other facilities

with similar geochemistry and contaminants and hydrogeology or detailed site characterization including

geochemical information from samples of existing (e.g., domestic water) wells from which conclusions

about biological mechanisms can be made. Table 5-2 lists the type of data that should be available to

permit a minimized first-year maintenance testing schedule (Table 5-1).
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5-2

Table 5-1. Minimal First-Year PM Schedule

Maintenance Test Testing Regime Time Interval

Borehole color video On new wells, then at pump service

intervals

Surface facility inspection. Inspect

and clean as needed at sampling

points

Monthly or whenever visited

Physical inspection

Examination of pulled components As needed, when pulled.

Well discharge or acceptance

(volume rate and pressure)

Weekly (recommend installation of

automated data collection in

accordance with CEGS 13405)*

Drawdown or head change Weekly (recommend installation of

automated data collection)

Graphical analysis Quarterly

Specific capacity test (well hydraulic

performance) on selected

representative wells.

Annually on selected trouble or

recommended wells or at

recommended shorter intervals

Hydraulic

performance

Pump performance. Conduct step

“pump” test (Section 2.1) of

centrifugal pumps and similar wear

analysis of positive displacement

pumps, compare to “nominal” data.

At least annually or at recommended

shorter intervals if pump service is

severe (Q/s and pump test can be a

single operation). Alternative: In

maintenance system, include triggers

for out-of-nomimal power readings.

Electrical (power) System and motor V, A, φ, Ω When visited for service (Recommend

installation of current monitors with

alarms)

PH, mV, and temperature At well start up and quarterly using

project onsite instruments (calibrated)

or routine (laboratory)*

Physicochemistry

Suspended particulate matter (sand,

silt, clay)

At well testing then at pump test

intervals

Biofouling microbial

component

BART analyses. After clog-typing,

pick suitable test type (IRB, SRB, or

SLYM) and monitor for change.

At well start up for baseline, then

quarterly on selected representative

wells.

Well hydraulic improvement and

pumping systems

As testing indicates Q/s or injection

rate drops below 90% or pumping

system degrades

Treatments and

service

Instrumentation calibration In accordance with CEGS 13405

* CEGS 13405 specifies continuous metering, monitoring, and recording equipment for parameters such

as flow, temperature, pressure, and physical-chemical properties of discharged fluids. It does not include

methods for cleaning or other O&M issues.
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Table 5-2 Troubleshooting New Site Data Needs

Parameter Potential Problems

Fe and Mn (total, Fe2+/Fe3+, Fe minerals,

Mn4+/Mn2+, Mn minerals and complexes)

sometimes other metals such as Al. Select based

on presumed geochemistry.

Indications of clogging potential, presence of

biofouling, Eh shifts. Fe transformations are the

most common among redox-sensitive metals in

the environment. Mn is less common but locally

important.

S (total, S2-/SO4

2-, S minerals and complexes) as

suspected due to site geochemistry.

Indications of corrosion and clogging potential,

presence of biofouling, Eh shifts.

pH. Indication of acidity/basicity and likelihood of

corrosion and/or mineral encrustation. Combined

with Eh to determine likely metallic mineral states

present.

Conductivity. Indication of TDS content and a component of

corrosivity assessment.

Major ions. Carbonate minerals, F, Ca, Mg, Na, Cl determine

the types of encrusting minerals that may be

present and are used in saturation indices. One

surrogate for many cations is total hardness.

Sand/silt content (v/v, w/v). Indication of success of

development/redevelopment, potential for

abrasion and clogging.

Biofouling parameters. See Chapter 2 Section 9: Select appropriate

methods to permit a complete but convenient

assessment of biofouling mechanisms present.

b. Note on monitoring levels of effort. Choices should be made on the basis of long-term site lifecycle cost-effectiveness. The cost comparison should be between the cost to perform the appropriate

maintenance vs. the cost of having the well system or the remediation project to fail to function properly

with possible replacement of numerous wells. If specific experience with particular contaminant or site

conditions permit a much reduced level of effort without impairing performance, this is acceptable.

However, history indicates that

• Maintenance monitoring is cost-effective compared to the alternatives.

• Decisions made to minimize prevention and maintenance monitoring based on short-term

experience may be regretted later as deteriorating phenomena result in performance

degradation.

(1) It may actually reduce operational problems if certain monitoring is intensified, at least on

certain critical wells. For example:

• Test pumps at least annually.

• Conduct graphical analyses of pumping tests monthly, instead of quarterly, for wells in which

rapid decline or fluctuation of specific capacity is noted.

y Conduct physicochemical analyses at least monthly on wells which exhibit highly variable

water quality.

y Add turbidity or (better yet) particle counting, using automated, in-stream sensors, to detect

upswings in particulate sloughing that often accompanies enhanced biofouling.

y Add microscopy of samples from biofilm flow cells (Smith, 1992) to visually observe
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5-4

changes in biofilm consistency, and analyze collected samples for changes in elemental analysis

and crystalline structure of encrusting compounds. This information is useful in adjusting

treatment programs.

(2) Rather than reducing monitoring, cost and labor savings can be realized by using automated

sampling and data reporting and computerized maintenance management software to minimize human

time investment. Automated systems should be evaluated periodically and verified manually.

5-3. Schedule for Reducing Maintenance After First Year

Maintenance (including monitoring) intervals can be reduced as trends are established. (Exception:

troublesome wells that may be on annual or more-frequent treatment schedules based on first-year

experience.) Typically, on wells performing adequately, the frequency of physicochemical and

biofouling parameter testing can drop to quarterly if little change in conditions is noticeable after one

year. Table 5-3 summarizes a post-first-year PM schedule.

5-4. Schedule for Intensive Maintenance for Critical Wells

a. Long-term intensive maintenance. As site experience develops (1 to 5 years), certain wells will

be identified that will require intensive maintenance to continue useful operation. Intensive maintenance

will include the following (detailed in Appendix C):

• Premaintenance testing of performance components.

• Removal of pump and inspection of components, repair and refurbish as needed.

• Chemical treatment (primary well and satellite wells).

• Mechanical development.

• Re-installation of well components.

• Testing (pre- and post-repair testing and PM testing, which includes parameters listed in

Tables 5-1 and 5-2).

b. Schedule. A typical schedule is 3 to 6 months for injection wells and 6 months to annually for

pumping wells. Where pump removal is determined not to be cost effective, or is especially difficult,

pump testing to determine its status on the above schedule is a second option.

c. Well system modifications for treatment.

(1) In situations where pump removal is expensive and difficult (and this situation cannot be

modified readily), some wells may respond well to in-well recirculating cleaning systems properly

installed and operated. Such systems involve installing a return-flow pipe string to the open zone below

the well pump, connected to the well pump discharge. An electronically actuated valve is controlled by a

timer or other control device that flushes the sump or screen to remove built-up slime, oxides and

sediment. Chemical feeds can be added to effect more aggressive cleaning.

(2) Additional wells should be installed at these locations to permit alternating wells in operation.

Wells should be sufficiently far away from their alternating partners to be outside the likely clogging

zones (if possible), but situated to maintain hydraulic control of the plume at this location.

(3) Satellite wells are recommended for introduction of cleaning solutions. Three to five wells

may be installed at regular intervals around the pumping well at a distance of 2 to 7 m (6.6 to 23 ft). The

distance depends on local hydraulic conductivity and the perceived degree of existing clogging).
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5-5

Table 5-3. Long-Term PM Schedule

Maintenance Test Testing Regime Time Interval

Physical inspection Borehole color video At each major rehabilitation (before and

after) or five years (whichever is sooner).

Concentrate on screen and other stress

points

Surface facility inspection. Inspect and

clean as needed at sampling points

Quarterly or each visit

Examination of pulled components As needed (at least test pump if not

pulling it annually). Wells should be

equipped for easy pulling if at all possible.

Hydraulic performance Well discharge or acceptance (flow rate

and pressure)

Weekly (recommend installation of

automated data collection in accordance

with CEGS 13405*)

Drawdown Weekly to biweekly. (recommend

installation of automated data collection)

Graphical analysis Quarterly

Specific capacity test (well hydraulic

performance)

Annually or at recommended shorter

intervals for specific representative or

trouble wells.

Pump performance. Conduct step

“pump” test (Section 2-2) of centrifugal

pumps and similar wear analysis of

positive displacement pumps, compare to

“nominal” data

At least annually or at recommended

shorter intervals if pump service is severe

(Q/s and pump test can be a single

operation). Severe: This is subjective. One

useful criterion: Pump replacement in 3 yr

or less.

Electrical (power) System and motor V, A, φ, Ω Weekly (Recommend installation of

current monitors with alarms)

Inorganic parameters At least quarterly using project onsite

instruments (calibrated) or routine

monitoring (laboratory)*

Physicochemistry

Suspended particulate matter (sand, silt,

clay)

Manually at well testing then quarterly

Turbidity (adds colloidal) In-line monitors (continuous)*

BART analyses. Pick one indicator type

based on past performance (IRB, SRB,

SLYM, DN) and use for a marker.

Quarterly. Watch others (IRB, SRB,

SLYM) at least annually. May be

discontinued if results vary little over

time.

Biofouling Microbial

Component

Biofilm flow cell for microscopy Annually on selected wells

Well hydraulic improvement and

pumping systems

As testing indicates Q/s drops below 90%

or pumping system degrades

Treatments and Service

Instrumentation calibration In accordance with CEGS 13405.

* CEGS 13405 specifies continuous metering, monitoring, and recording of parameters such as flow, temperature,

pressure, and physical-chemical properties of discharged fluids.

(4) Chemical feeds (pellet or solution) are sometimes prescribed for well maintenance cleaning.

Operators should resist any temptation to rely on chemical feed systems themselves to maintain wells.

The feed suggested in item (1) would inject a cleaning solution along with flushing. Chemical choices

recommended may be found in Section 6-1.
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Chapter 6

Chemical Dosage for Wells

Chemical treatment in a preventive mode is a major aspect of maintenance of well and fluid system

performance. ASTM D 5978, which addresses the maintenance of monitoring wells, does not recommend

the use of chemicals, but redevelopment only. This restrictive guidance is not extended to pumping and

injecting wells on HTRW sites, for which the responsible use of chemicals in PM redevelopment is

usually needed to improve the well’s effectiveness. Experience shows that chemical choices in well

treatment are often made based on incomplete information or vendor sales literature. And while

information should not be dismissed if it comes from a commercial source (as vendors frequently seek to

educate), it is crucial that personnel engaged in the planning of well system O&M seek expert advice and

review publications specifically written for these types of sites to become well acquainted with the

features of chemical choices, both for effectiveness and safety.

6-1 Lists of Chemicals to be Used

a. Issues in chemical choices. The listings of chemicals in this section include brief summaries of

the chemicals’ uses. Detailed information is provided in Borch, Smith, and Noble (1993), ADITC (1997),

and Smith (1995).

(1) Reactivity with constituents of contaminated ground water is an issue in HTRW remediation

and monitoring well maintenance. Table 2-4 provides a summary of common reactions.

(2) Cost is frequently cited as an issue in choices made as to whether to use chemicals and

electing which ones and how much to use.

(a) Three factors affect the market price of chemical products used in well cleaning:

• Actual process and shipping costs.

• Premiums for purity and standard certification.

• Degree of commercial exclusivity (particularly with proprietary products).

(b) In terms of effectiveness, a more expensive chemical may be a better choice and therefore

cost-effective. Among the acids, for example, organic-based and more concentrated products are more

expensive than inorganic acids, primarily due to process costs. However, their effectiveness against

biofouling and relative handling safety may outweigh the actual material cost differential.

(c) The USACE directs that HTRW site project and O&M management take a “long-view”

approach to O&M cost-effectiveness calculations, i.e., to consider cost-effectiveness on a life-cycle cost

basis. Available research (Sutherland, Howsam, and Morris 1994) in water supply applications indicates

that even aggressive PM is cost-effective compared to losses in efficiency, equipment repair, and well

failure. HTRW ground water plume management adds the factor of the project mission, i.e., the cost of

failure to control contaminated ground water.

(d) Warning. The chemicals used in O&M are all reactive and pose risks to skin, mucous

membranes, and other soft tissues of humans, and are potentially harmful to the environment if handled

improperly. They should only be used by trained personnel familiar with their safe use, and who are

equipped with proper respiratory and skin protection. Material Safety Data Sheets (MSDS) and other

safety information must be reviewed by all personnel involved (mandatory). No HTRW remediation
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6-2

project should employ personnel or contractors to perform well cleaning who cannot clearly demonstrate

competence in use of, and a thorough understanding of the potential reactivity between well cleaning

chemicals, contaminants of concern and other chemicals present on the site.

b. Chemical classes and properties. The following paragraphs summarize chemical purposes and

effects, safety, handling, and effectiveness features.

(1) Acids. Acids are used to dissolve hard encrusting materials, including Fe and Mn oxides and

carbonate deposits. Tables 6-1 and 6-2 list acids most commonly used in well rehabilitation. Table 6-1

lists recommended compounds. Table 6-2 lists commonly used well cleaning compounds not

recommended by the USACE for HTRW well PM treatment.

Table 6-1. Recommended Acid Compounds

Acid Descriptors Safety & Handling

Safety: Use gloves, splash protection, and

respirator at barrel end*. Does not require

placarding for shipment.

Acetic acid Excellent biocide and biofilm

dispersing acid. Relatively safe to

handle. Often a major component of

biofouling “enhancers” and brandname mixtures specified for

biofouling. Acidizing to pH < 2 with

sulfamic acid recommended (rapidly

loses acid power without). Should use

food or good industrial grade > 85 %

acid. (variation: glycolic or hydroxyacetic acid).

Handling: These solutions freeze at working

ambient temperatures: glacial at 10o

 to 12.8o C

(50o

 - 55o F), 84% at 4.4o C (40o F), 15%

(working solution) ~ 0o

 C (32o F). Make the

dilution at an ambient above the stock solution

freezing point.

Safety: Relatively safe to transport and handle

(solid, dust inhalation should be avoided).

Sulfamic

acid

Relatively effective against carbonate

scales, and as an acid enhancer for

acetic acid. Not effective alone

against biofouling or metal oxides.

Handling: Solid, less aggressive than HCl

(Table 6-2). Use gloves, dust mask and

goggles. Provide proper ventilation. Circulate

during mixing.

Other Safety: Safe to transport.

organic acids

For example, oxalic and citric acids.

Useful as chelating agents. Oxalic

acid is also effective as a primary

acidizer in low-Ca water. Often form

insoluble precipitates in high-Ca

waters.

Handling depends on form (typically granular

solids). Use gloves, dust mask, and goggles.

Provide proper ventilation. Circulate during

mixing.

* Refer to Chapter 7 and health and safety references.

(2) Biocides. These agents are used in the attempt to reduce bacterial populations. As in water

supply well cleaning (Borch, Smith, and Noble 1993), in HTRW well cleaning (maintenance or

rehabilitation), reducing bacterial numbers is typically impractical and no longer considered a primary

objective (Smith 1995; Alford and Cullimore 1999). The reduction of hydraulic impact and other

symptoms for the longest time possible is the primary objective.

(a) Chlorine (typically sodium or calcium hypochlorite (AWWA Standard B300)). Sodium

hypochlorite is liquid and more likely to retain solubility in high total dissolved solids solutions. One

procedure used to limit and remove biological encrustation is termed a "shock" chlorine treatment.

Standard ANSI/AWWA C654-97 covers the procedures for shock chlorination and bacteriological testing
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6-3

for the disinfection of wells for potable water service. Well cleaning maintenance and rehabilitation are

not standardized but methods are available (Borch, Smith, and Noble 1993). Concentrations as high as

500 to 2,000 mg/L of chlorine are usually desirable for this. This is NOT RECOMMENDED for HTRW

maintenance treatment applications. Chlorine is a powerful oxidant that reacts with organic compounds,

causing chemical alteration of the compounds to more difficult-to-treat forms or to potentially explosive

situations with eruption of chemicals at the surface. This latter reactivity, particularly in light of the

carcinogenic properties of some chlorinated organic compounds, is the basis for increasing regulatory

scrutiny of the use of chlorine for purposes other than maintaining potability of water.

Table 6-2. Common Well Cleaning Chemicals in Use -- Not Recommended

Acids Safety Concerns* Effectiveness

WARNING: Extremely

hazardous to handle. Volatile

liquid: Requires respiratory and

splash protection.

Powerful for removing mineral and

inorganic metal oxide scale. Relatively

ineffective against biofouling and

deleterious to stainless steel (CEGS 13405).

Muriatic acid (HCl)

DO NOT mix with chlorine

reaction in well can lead to

surface eruption of chemicals

and Cl gas; use inhibitors for

metal well screens but note that

some industrial inhibitors should

not be used in potentially

potable ground water (toxicity),

and gelatin (safe) provides

nutrient and inoculum for

regrowth.

Steel industry pickling liquor by-product.

Quality is a problem, with cadmium and

other impurities often present in industrial

grades, although NSF 61** certified

solutions are available. NOT

RECOMMENDED for maintenance

treatments.

WARNING: Extremely

hazardous to handle. A strong

food grade quality acid, readily

available, 75%, in 208 liter (55

gal) drums and 45.4 – 56.8 liter

(12-15 gal) containers.

Effective against metal and mineral

hydroxides. Somewhat effective against

biofouling, but no more so than some other

mixtures.

Phosphoric acid

Quite hazardous to handle. Full

breathing mask and splash

protection required. Adequate

ventilation a must.

Leaves phosphate residue behind for

bacteria. NOT RECOMMENDED for

maintenance treatments.

* Refer to Chapter 7 and health and safety references.

** NSF International Standard 61 covers the safety of chemicals for human contact.

(b) Ozone. Ozone (O3) is formed by exposure of oxygen O2 to strong electrical charges. Ozone

has to be generated at the point of application due to its instability, which precludes storage under

pressure or transport, making it largely impractical for rehabilitation. Ozone does not have a recognized

practical application in well maintenance treatment, although it may be used in piping system treatment to

repress biological activity (CEGS 13405 and EM 1110-1-4008).

(c) Hydrogen peroxide. Like ozone, aqueous hydrogen peroxide is a powerful disinfectant and

oxidant. It has been used with some effectiveness in removing well biofouling in both water supply and

environmental wells. There are a variety of sources of "generic" 50% peroxide mixtures available

commercially. It should also be noted that H2O2 is aggressively attacked by bacterial enzymes. It breaks
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6-4

down to form H2O and O2, and the resultant oxygenation can actually enhance microbial growth away

from the well and the lethal oxidant zone. It may be used in piping system treatment to repress biological

activity. (CEGS 13405 and EM 1110-1-1008).

(d) Potassium permanganate. Potassium permanganate (AWWA B303), another powerful oxidant

used in maintaining industrial process systems and in water treatment (CEGS 13405) for relatively

uncontaminated water, is not used as a primary oxidant in well treatments. Dissolution of metals and

biofilms is more effectively accomplished using acids (Section 6-1c(1)).

(e) Use of heat. In some cases, water heated to 54o

 C and recirculated over several days is

sufficient without chemicals at least in the short term. Note: Heat propagates from the application source,

but typically accumulates in the well structure due to the poor thermal conductivity of soil materials. Heat

can actually enhance growth away from the thermal shock zone, as well as cause drying and shrinking

clays such as bentonite grout. Using heat alone is also very inefficient in terms of fuel or power to

generate thermal energy. The best approach to using heat is in a process such as the blended chemical

heat treatment method described below (6-1.c) with a prudent selection of chemicals (Alford and

Cullimore, 1999).

(3) Sequestration. In well treatment, these compounds are most properly used in low

concentrations in chemical blends as aids in acidizing mixtures to retain biofilm and metal oxide

components in solution for removal, once they are dissolved and dispersed in the water column. Examples

are various polyphosphates, pyrophosphates, and polyacrylamide-based compounds. In addition, acetic

acid and citric acid (Section 6-1c(1)), and some proprietary acid formulations also have related chelating

properties.

(a) Phosphate-containing compounds are NOT RECOMMENDED for maintenance well

treatment. Residuals of the compounds themselves (higher molecular weight (MW) polymers) and

breakdown products (low-MW pyrophosphate and orthophosphate or phosphate) remain behind in the

formation (attached to clays). The presence of an enhanced phosphate resource induces enhanced biofilm

development, often at the edge of development influence.

(b) Polyacrylamide and similar polyelectrolyte wetting agents provide the desired effects of

dispersing clogging deposits and clay/silt buildup without being phosphate sources. These compounds are

not readily attacked by microorganisms. They should be handled, used, and ultimately disposed of

according to manufacturer/supplier and MSDS instructions.

(4) Reactivity. Consult reactivity tables (e.g., Table 2-4) for problems with ground water

constituents. EM 1110-1-1008 provides guidance in system material reactivity.

c. Blended method treatments. Typically, no one chemical type will address all encrustation and

biofouling removal, suspension, dispersal, and repression needs. Blending approaches can permit more

effective removal of multiple problems, or treat a single difficult problem more effectively (Smith, 1995;

Alford and Cullimore, 1999). Appendix C includes one scenario. The exact blend of chemicals for a

particular well field situation is determined based on an analysis of the needs for cleaning the clogging

materials present and ground water quality.

d. Role of development. It should be emphasized that all chemical mixtures are far more effective

with adequate mechanical mixing and development, and should be specified based on an adequate

analysis of the problem.
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6-5

e. Purge water handling. Any purge water should be disposed of properly in wastewater

treatment or surface spreading on soil. The definition of “properly” will depend on the chemical mixtures,

their chemical properties (e.g., pH), and the sensitivity of the treatment or land system. Discharge to any

surface waters must be avoided. Phosphate-loaded water discharged to surface waters can cause algal

blooms and oxygen depletion, resulting in suffocation of aquatic animals. Additionally, pH shock is toxic

to aquatic life, and turbidity can suffocate.

6-2 Use and Interpretation of MSDS

a. Requirement. Having MSDS on hand is a requirement of governing agencies (including

USACE) and a central feature in safety plans involving chemical safety. The Occupational Safety and

Health Administration (OSHA) requires the MSDS to accompany each container of reactive chemical

from point of origin to point of consumption or final disposal. Each person handling each chemical must

verify that he/she has read the MSDS, or has had it read to him/her and that he/she understands the

precautions necessary.

b. Use. MSDS must be on hand to provide guidance in personnel exposure problems, reactivity

concerns, and neutralization recommendations, and to provide information on basic physical properties

(e.g., the relatively high freezing temperature of organic acids). The MSDS of proprietary chemical

blends also permits interpretation of their contents and modes of operation in treatment.

6-3 Calculation Work Sheets

This pamphlet provides calculations for well volume dosages, and includes well volume/foot tables for

common well diameters. These are found in Appendix D. Appendix C offers recipes for commonly used

mixtures.
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Chapter 7

Health and Safety Concerns

HTRW well system O&M has a number of critical health and safety issues related to general well and

pump mechanical and electrical operation and control, as well as specific concerns of handling potentially

hazardous formation and treatment fluids, and related issues such as confined space operation.

7-1 Health and Safety Plan

O&M safety must be a component of overall site safety. The development and implementation of a

specific but flexible plan is needed, including personnel expertise and compliance, and training to make

personnel thoroughly familiar with chemical and mechanical activities. Depending on the specific nature

of the well system and the nature of the contaminants and treatment chemicals, O&M activities will

require worker hazard analyses and compliance with any applicable OSHA standard found in 29 CFR

1910 and/or 29 CFR 1926, in addition to any applicable requirements of EM 385-1-1. In all cases, the

O&M safety and health managers will be required to comply with 29 CFR 1910.132 through the

performance of a site-specific hazard analysis, the selection of personal protective equipment (PPE)

appropriate to protect workers from the hazards identified, a written hazard assessment certification, and

worker training in the hazards and PPE to be used. The following guidance will assist in that effort.

7-2 Level of Protection for Mixing and Well Application

Well maintenance treatments involve the use of reactive chemicals (Sections 6-1 and 6-2). Once a

chemical regime is selected, the appropriate use of chemical-resistant gloves, boots, and apparel, full-face

splash shields, and other specific protection such as for handling hot and supercold solutions should be

specified. See Section 6-1 and other references. An excellent strategic policy for safety is to, as a rule,

employ treatment mixtures that minimize hazard and the likelihood of personal injury due to error, while

still being effective. The mixture in Appendix C is one such treatment.

7-3 Chemical Handling Hazards

a. Transferring chemical solutions. Typically, the major exposure injury risk point during PM

treatment is at drums containing concentrated acid, caustic, or oxidizing agent solutions. Spilling or

transfer hose troubles may result in skin exposure. Vapors may cause mucous membrane and eye tissue

irritation or damage. Persons handling concentrated chemicals should wear full-face splash guards and

respirators and chemical resistant clothing and gloves. Persons handling dilute solutions may work with

care in OSHA Level D gear (29 CFR 1910).

7-4 Mixing Chemicals

a. Mixing hazards. Mixing of concentrated reactive solutions can result in personal hazards. For

example, neutralization of acids poses a potential hazard if basic compounds are added too rapidly to

strongly acid solutions (pH <5). Significant foaming may occur.

b. Hazard review. Personnel should review how to handle specific chemical source stock and

solutions. MSDS provide general guidance but should not be relied upon for complete instructions, which

should be in the site-specific O&M Site Safety and Health Plan (Section 7-1). General chemical mixing

safety requirements are listed below:
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7-2

• Personnel should always add acid to water and not vice versa.

• Strong oxidants should never be used where hydrocarbon concentrations are high in well

water solutions, as ignition is a low-but-not-zero probability.

• Alkaline and caustic compounds should be added slowly to acidic compounds when

neutralization is required, and never added to wells when acid solutions are still in the well.

• Hoses, valves, and connections should be secured and not leaking. Spraying acid or oxidant

chemicals can result in dermal burns and clothing damage.

• All work should be conducted in unobstructed and well-ventilated areas.

• Personnel must routinely review MSDS and company recipe sheets before each treatment

event and work at a deliberate pace, avoiding rush.

• Extra lime or soda ash should be kept on hand to treat spills, and eyewash packages and

abundant clean water should be kept close at hand for dilution when personnel are splashed.
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Chapter 8

Checklists

Checklists facilitate the implementation of the site well array O&M plan by providing site personnel with

concrete tasks and schedules. Checklists for the following may be found in Appendix D.

8-1 Type and Frequency of Data to be Collected

Checklists should include daily and totalized flows, pressure per well, and other data (pH, drawdown).

Consult Chapter 5 for frequencies.

8-2 Well Maintenance Log

Table 8-1 lists the recommended information to be logged during a PM treatment event.

Table 8-1. PM Treatment Log Items

Data types Description

Physical properties Well identification and diameter, depth to screen, screen interval, total

depth

Remediation measures Type and amount of chemical used, surging method and times

Periodically and before and after remediation --

 Amount and identification of sedimentation

 Flow

 Well drawdown

 Piezometer drawdowns

Related measurements

Power data and notations on instrumentation

Notes on repairs and

replacements

Modifications to the well structure and all equipment data

Related comments All potentially pertinent information (weather, delays, equipment

problems, discussions over methods, change orders)

Itemization of costs For budgeting and future reference.

8-3 O&M Calculation Work Sheet

Specific formula calculation sheets should be provided, specific to the wells to be treated. See Section 6-1

and Appendix C for chemical and treatment choice information.

8-4 Other Records

a. Field data sheets. As discussed in Chapter 2, drawdown and flow sheets should be developed

for routine field data collection and should include all relevant data columns. A variety of examples exist

from text, government, and commercial sources.

b. Cost-effectiveness calculation spreadsheets. Sutherland, Howsam, and Morris (1994) provides

cost-effectiveness work sheets and spreadsheets adaptable for HTRW site use.

c. Work orders. Most organized sites generate work orders for activities such as PM well

treatment or equipment repair. These may be paper forms or generated in software maintenance

management systems.
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Chapter 9

Suggested Maintenance (Minimum and Optimum)

The following paragraphs list recommended maintenance practices, intervals, and evaluation processes.

They are adapted from more in-depth discussions elsewhere (e.g., Borch, Smith, and Noble 1993;

Howsam, Misstears, and Jones 1995; Powers 1992; Smith 1995; ADITC 1997; NGWA 1998) and project

experience.

9-1 Design Aspects

A variety of design considerations can serve to prevent or slow well system deterioration, and facilitate

maintenance and rehabilitation in the future. In many cases, the improvements cost little or no more than

inferior designs and materials initially, and save money in life-cycle costs.

a. Improved materials. Corrosion- and deterioration-resistant materials slow the deterioration of

well components and limit recurrence of preventable problems, making the success of maintenance

actions more likely. EM 1110-1-4008 provides information on material compatibility. Specific to well

equipment, polyvinyl chloride (PVC) casing, for example, is corrosion-resistant and suitable for most

HTRW applications. Alternative metal casings are available where plastic or fiberglass casings are not

suitable (Smith 1995; NGWA 1998). Notable product developments (approaching 20 years in service)

include the widespread availability of all-stainless-steel and stainless-and-plastic pumps, high-quality

rigid plastic pump discharge (drop) pipe with twist-on-twist-off connections, and flexible discharge hose

(specifically designed for well pump use) composed of reliable, high-strength, corrosion-resistant material

that permits easy pump service. Relatively smooth pump interior surfaces and corrosion resistance are

showing increasing intervals between pump service events.

b. Other pump selection considerations. Pump motor and discharge-end product lines can seem to

have a remarkable sameness in a competitive market. On the other hand, pumps may be marketed for

"environmental duty" which may not be superior to other products for aggressive ground water pumping

applications. Some considerations:

(1) Pump end material selection.

(a) A material designation of "stainless steel" includes a range of corrosion-resisting alloys. Some

do well in anaerobic environments typical of high-organic-carbon water (e.g., Type 316 and better), and

some do not (Type 304). The alloy should be selected to be compatible with the service environment.

(b) Welding and stamping alter the corrosion-resisting characteristics of stainless steel alloys so

that the manufactured product may not match the resistance of the unaltered alloy. In some cases, a cast

stainless bowl selection may be superior.

(c) While versatile, stainless steel may not suit every situation. In some high-chloride, biocorrosive environments, only high-silicon bronze or plastics may provide suitable service life. At high

temperature or high radiological activity , some plastics degrade at unacceptable rates. In addition to bowl

and impeller materials, selections of bearing materials and designs are factors in selection.

(2) Pump end hydraulic efficiency. Higher efficiency pump ends are recommended. Pump

impeller-bowl designs and numbers of stages should be matched to the operating head conditions.
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(3) Submersible vs. lineshaft installations. In general, submersible models are more versatile but

characteristically provide less wire-to-water efficiency than many lineshaft turbine models. Lineshaft

installations offer the advantage of having the motor at the surface, where it is accessible, heavy motors

for very large pumps are not suspended downhole, and motors are less expensive to repair. Disadvantages

of lineshaft installations include:

• The need for a lineshaft and its associated bearings which require lubrication and are

vulnerable to wear, especially in aggressive, biofouling water.

y The need to use steel column pipe, which is subject to rapid corrosion.

y Restricted access at the surface for drawdown measurement and other access to the well

casing.

y Greater skill is needed in lineshaft pump repair, and wells must be very straight and plumb.

y Surface-mounted motors must be protected from weather and heated or cooled as needed.

(4) Achieving a balance of equipment features. As exact matches to conditions and ideals may not

be possible, pump choice may be a balance of features. In general, the highest efficiency pump models

should be used. Exceptions occur where service is so severe that short operating lifespans can make more

expensive, tunable pumps not cost-effective to operate. In these cases (particularly where efficiency

differences are minor), low-priced but serviceable pumps that can be discarded and replaced or cleaned

may be the better option.

c. Computers and controllers. Automated water-level and flow information facilitates data

analysis and planning. Devices exist to provide "real time" water-level and flow measurements without

personnel being onsite. SCADA systems originally developed for process treatment can be adapted for

well fields, permitting rapid, easy, and continuous monitoring of well and pump hydraulic performance,

and even physical-chemical changes. Pump controllers help to maintain regular current flow of the proper

characteristics and phase to pump motors, thereby prolonging motor life and shielding motors from line

surges. All pump motors should be equipped with automatic controllers.

d. Suction flow control. One technology that has developed in recent years is the refinement of the

controlled-inflow pump tailpipe referred to as a suction flow control device (SFCD). These simple

devices are perforated pump intake pipes. The perforations are made in a pattern that forces flow to enter

the well in a more cylindrical fashion (Nuzman 1989 and Ehrhardt and Pelzer 1992), instead of

• An upward-faced cone pattern typical of pumped screened wells in which almost all flow

enters through the top 10 to 15% of the screen when the pump is above the screen.

• Preferentially at the point where the pump is located within the screen, typical of many

HTRW pumping wells.

Unfortunately, practical commercial access to the best quality devices is at present still limited to Europe

and the Mediterranean, and inclusion in U.S. site planning has to await commercial availability in this

country.

e. Well and water system modifications to facilitate maintenance. A maintenance-friendly

wellhead setup is important to minimize the difficulty of performing maintenance. Issues include meeting

limits to avoid confined space designation, making the well seal secure but removable, and discharge

head and instrument connections easy to detach. Table 9-1 provides recommendations for wellhead

features to facilitate maintenance.
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f. Wellhead chemical treatment.

(1) A hydrant should be installed between the well pitless discharge and the well house flow

meter-valve assembly for discharge to waste during treatment. Several suitable self-draining hydrant

styles approved for potable water distribution are available on the market (ANSI/AWWA C503 and

CEGS 02510). During the well treatment process, a hose may be run from the blowoff hydrant to

containment and treatment.

(2) Chemical feed pumps can be used to meter chemical mixtures into wells (CEGS 11242). The

manufacturer should also be consulted about the chemical compatibility of diaphragm and housing of the

liquid end. Also, the suitability of hose installed for short term, periodic service feeding pH 2 solutions

should be double-checked.

Table 9-1. Design and Equipment for Wellheads to Facilitate Maintenance

Recommended Features Feature Application

Room exists for personnel to operate and

manipulate equipment around the wellhead,

reasonably accessible, dry and stable wellhead

area, elimination of confined-space-entry

conditions.

Improves accuracy and reduces the potential for

accidental injury or equipment damage or loss.

Minimizes personnel needs for routine tasks;

reduces time and equipment required for

maintenance events.

Locks, caps, or security apparatus are corrosionand weather-resistantPersonnel do not waste time and risk injury or

equipment damage attempting to perform

maintenance. Instrumentation is not easily

damaged by heat, cold, or vandalism.

Water-level measurement access and flow

readings are easily obtained

Personnel can perform these tasks efficiently and

willingly.

Wellhead structures and fittings permit easy

removal of pumps and downhole equipment.

Pumps can be removed quickly, saving money.

Piping and valving is designed to limit pressure

drops, and permit convenient flow diversion and

pipe maintenance.

Clogging is minimized, and maintenance flushing

and pigging can be accomplished. See paragraphs

9-1f and 9-1g.

Water quality taps are accessible and protected

from weather and corrosion.

Samples can be readily obtained and taps

maintained.

(3) Systems have been developed to systematically redevelop with the pump in place, and

designed to provide treatment chemicals to the screen where past pump-in-place designs were not

effective. An example is a system in which a valved return flow pipe is installed to permit periodic or

demand flushing of the well water column. These should be considered as maintenance treatment options.

g. Distribution pipeline maintenance. Distribution lines from wells may also develop deposits of

iron oxides and biofilm. If oxidation and fouling in wells are kept to a minimum, lines are likely to remain

relatively clean. However, line clogging is a very common problem in systems pumping contaminated

ground water to treatment.

(1) If the system head shows signs of increasing, a program of pigging and flushing can be

instituted. Pigging is the process of running a soft plug with a rough, abrasive outside surface through the

lines to remove deposits. (The procedure is described in Deb et al. (1990)). Some system modification
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will be needed to accommodate the procedure, and it is recommended that planning for this option be part

of well system design. Pigging requires:

• An upstream entry point for the pig (for example at a well house).

• A means of providing water pressure to propel the pig (water pressure from a potable water

system fire hydrant would suffice).

• An outlet collection point for wastewater and pig.

(2) Alternatives such as electrostatic dispersion of colloidal fouling components have also been

suggested, and possibly have application.

h. Well array design recommendations. These design recommendations are detailed below.

(1) Have enough wells installed in a pumping or injection array to permit continued operation and

plume control while wells are out of service (being treated or pumps replaced).

(2) Install a ring of treatment wells around pumping or injection wells subject to clogging

(Section 5-4). These can greatly improve treatment success in the near-well formation by providing a way

to force treatment chemicals toward the pumping well screen from the outside and also to provide more

access for agitation of the near-well formation.

(3) On sites with very deep wells, options (1) and (2) may be quite expensive. In these cases,

where both replacement and rehabilitation may be very expensive and difficult, designing and planning

for a rigorous maintenance defense of the existing pumping wells are especially important.

9-2 Chemical Addition

a. Methods of addition. Chemicals may be introduced into wells by gravity (tremie), pumping in

against water column pressure, and high-pressure jetting. A feature of each is that chemical solutions are

directed to the screen region and not simply poured into the well. For maintenance treatments, simple

pouring and pumping (versus jetting or pressurizing) is usually sufficient. Jetting may be used for more

completely developed clogging situations. Note that both redevelopment methods and chemicals used in

maintenance (as well as rehabilitation) treatments can be hazardous to personnel and possibly damaging

to well structures.

b. Professionalism. Any treatment program must be initiated by professional contractors highly

familiar with these treatments. Site personnel can be trained in the safe use and evaluation of the

effectiveness of these methods by the contractor.

9-3 Mechanical Agitation

Chemicals introduced should be mixed through the screen column, either through surging (see Section

9-5) or recirculation pumping. As it is mixed and pumped in, and later during development, the solution

should be checked and adjusted to maintain pH <2. Current research under way at the Canadian Federal

Government's Praire Farm Rehabilitation Administration's geotechnical laboratory suggests that most

chemicals should have a maximum in-well contact time of less than 10 hr where clay swelling is a

possibility.
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9-4 Chemical Recovery

Chemical solutions containing biofilm, metal oxides, and other solid debris must be removed from the

well column. It is essential to note that neutralization should never be conducted in the well column itself,

because

• Clogging material will drop out of suspension or solution.

• Explosive effervescence is possible when caustic solutions are introduced into solids-laden

acid solutions.

a. Containment. Containment and treatment such as neutralization are then necessary before

release into the environment. Options include:

(1) Pump into holding tanks. Development slurries are typically best pumped to pretreatment

tanks for settling and acid neutralization. Such tanks should be sufficiently large to hold three to six times

the borehole volume so that development (Section 9-5) does not have to stop. Other options include

neutralization "on the fly" in smaller tanks using a calculated feed rate of neutralizing chemical solution.

(2) Divert to existing lagoons. On occasion, slurries may be diverted to surface containment and

permitted to lose acid or oxidant power. Solids may settle in place.

(3) Divert to treatment plant. Typically on HTRW remediation sites, water treatment is available,

and development slurries must pass through them prior to release. Typically pretreatment is necessary.

The tolerances and requirements of the treatment process should be known and not exceeded.

b. Regulatory aspects. Environmental regulations and standards that apply to such impoundments

apply. Project agreements with regulators and local regulations may need to be checked before

discharging to existing treatment plants or lagoons if they were not originally intended to accept such

waste. Ultimately solids must go to secure disposal per regulatory requirement.

9-5 Well Development

Practically all methods of drilling cause compaction of unconsolidated materials of variable thickness in

an annulus around a drill hole. In addition, fines are driven into the wall of the hole, drilling mud invasion

may occur to a greater or less extent, and a mud cake (if used) may form on the wall of the hole. These

effects are well described in standard well construction references such as ADITC (1997) and Driscoll

(1986).

a. Defining well development and redevelopment. Well development is the final well construction

step that

• Removes formation damage caused by the borehole drilling process.

• Establishes the optimal hydraulic contact possible between the well and the aquifer formation

supplying fluids to (or accepting fluids from) the well.

Redevelopment is the process of using development methods to remove accumulating clogging material

from around an installed well.

b. Well development and redevelopment effects. The importance of proper initial well
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development and redevelopment in well maintenance is difficult to emphasize enough. Proper well

development breaks down the compacted borehole wall, liquefies gelled mud, and moves both mud and

formation fines into the well, from which they are removed by bailing or pumping. This action creates a

more permeable and stable zone about the screen or intake bore. The stabilization of the formation

adjacent to the well intake that is achieved by development can practically eliminate sand pumping, and

contributes to a more efficient well, longer well life, and reduced operation and maintenance costs. EM

1110-2-1914 and TM 5-813-1 provide general guidance on well development. Numerous detailed

references on development methods are available, including ADITC (1997), Driscoll (1986), and Roscoe

Moss Company (1992). Borch, Smith, and Noble (1993) provide information and guidance from a

redevelopment perspective. NGWA (1998) provides specific pumping well methods description and

guidance.

c. Well development and redevelopment methods.

(1) Overpumping. The development process consists of continuous or intermittent pumping at

pumping rates up to 1-1/2 times the design capacity. Overpumping lacks the necessary in-and-out action

of optimal development action but can be conducted with available well pumps.

(2) Surging and bailing (utilizing surge block). The development process is carried out by surging

and bailing the well. The surging is done by a single or double solid (or valved) surge block with

development water and sediment removed typically by airlift pumping. Surging should be conducted with

tools capable of a 0.3- to 0.6-m/sec (1- to 2-ft/sec). stroke and capable of working the screen in 0.6- to

1.5-m (2- to 5-ft) sections, concentrating on known trouble spots. One variation is swabbing (e.g., Roscoe

Moss Co., 1992).

(3) Surging and pumping. Where there is insufficient submergence for airlift pumping to work

properly, development can proceed using surging and pumping with a well pump. Pumping is conducted

through the surge block which incorporates a piece of the suction pipe in the fabrication of the block, at

rates up to one half of the design capacity. Upon completion of the development work, the well is cleaned

to the bottom. A variation of surging and pumping and overpumping, especially useful in tight wells,

employs a well pump moved up and down with a reversible pump puller. Pumps especially equipped for

this purpose with attached surge block collar, etc., are available. Care must be taken to ensure that air

does not enter the formation, but is only used to move fluid, which carries the kinetic development force

(see paragraph 9-5e).

(4) Hydraulic jetting. Development is accomplished by simultaneous high velocity, horizontal

jetting and pumping. The outside diameter of the jetting tool must be 1 in. (about 25 mm) less in diameter

than the screen inside diameter. The minimum exit velocity of the jetting fluid at the jet nozzle should be

150 ft/sec (45 m/sec). The tool is rotated at a speed less than 1 rpm and positioned at one level for not

less than 2 min and then moved to the next level, which is no more than 6 in. (150 mm) vertically from

the preceding jetting level. Pumping from the well should be at a rate of 5 to 15% more than the rate at

which water is introduced through the jetting tool. Water to be used for jetting must contain less than 1

ppm suspended solids.

(5) Air development. Development is conducted:

• Using a single pipe air pumping system either using the casing or the bore hole itself as the

eductor line (casing open) or with the casing closed to the atmosphere.

• With a dual-line air system employing an air introducing pipe and an air and water eductor

line.
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(a) Sizing. Compressors, airlines, hoses, fittings, etc., should be of adequate size to pump the well

by the airlift method at l-l/2 to 2 times the design capacity of the well. Each case is specific in terms of

depth, submergence, well diameter, and screen hydraulic conductivity. For wells less than 300 ft (91.4 m)

in depth, with 60% submergence possible, approximately 0.75 cfm of air compressor capacity is needed

per gpm (0.133 cfm) (~5.6 m3

/sec of air per 1 m3/sec water) of anticipated pumping rate (Driscoll 1986,

Fig. 15.12). In practice, a 375-cfm compressor developing 100 psi can usually pump 400 to 500 gpm

(approximately 44 to 67 cfm or 1.25 to 2.0 m3

/sec) of water with proper airline submergence.

(b) Development process. The first goal is to establish a piston effect (surging) and not to conduct

airlift pumping. In surging, sufficient air is fed to raise the water level as high as possible, then released to

let it drop. Airlift pumping is then used to pump the well periodically to remove sediment from the screen

or borehole. When the well yields clear, debris-free water, the airline is lowered to a point below the

bottom of the eductor line and air introduced until the water between the eductor pipe and the casing is

raised to the surface. At this time the airline is raised back up into the eductor line causing the water to be

pumped from the well through the eductor line. The procedure of alternating the relative positions of the

air and eductor line is repeated until the water yielded by the well remains clear when the well is surged

and backwashed by this technique.

(6) Combination tools and methods: The better features of several tools and methods can be

combined. For example, combination surging and jetting tools are used to surge while jetting in acid.

d. Care in performing development. To avoid applying forces on the casing, screen, and grout that

are beyond their capacity for resistance, care and attention to detail are required in development and

redevelopment. Sufficient force, efficiently supplied, is needed to set formation particles in motion and to

sheer off encrustation. However, this does not have to be violent force that damages the well. For

example, causing an excessive difference in hydrologic pressure between the outside and inside of a

casing may result in casing distortion. Sharp shock loading or unloading of some well screens may cause

distortion or collapse.

(1) Development typically should proceed in 2.74- to 4.57-m (3- to 5-ft) segments.

(2) Tools should not impact sharply against casing joints or screen rods.

(3) In air development, especially, there is a tendency to “overdo it.” Sufficient air flow volume

(cfm) should be available (paragraph 9-5d(5)(a)) to mobilize the water in the well and the near-well

formation, but being careful to not disturb the filter pack. Exceeding a 10:1 air-water volume ratio can

actually reduce airlift pumping flow rates because the well is impeded by excessive air volume.

9-6 Maintenance Monitoring Well Deterioration and Redevelopment Evaluation

a. Evaluation in the PM plan. Including recommendations, processes, and checklists for methods

to evaluate well performance, its deterioration, and repair and treatment results in the well system PM

plan permits evaluation of treatment effectiveness, the need for additional actions, or changes in

subsequent treatment. An overview of maintenance monitoring schedule and parameter recommendations

is provided in Sections 5-2 and 5-3.

b. PM evaluation instrumentation recommendations. The following are some specific instrument

recommendations for maintenance monitoring:

(1) Physical-chemical monitoring for maintenance water quality testing. Electronic colorimetric

or spectrophotometric instruments and electronic pH-mV, temperature, and conductivity meters are
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sufficient for PM monitoring with proper calibration (CEGS 13405). If there is an established

maintenance and calibration schedule for all instruments, accuracy is not sacrificed using onsite,

commercially available instrumentation, and the greater frequency of analysis possible economically

provides more data points to plot trends.

(2) Biofouling microbial component.

(a) Sampling. Pumped grab methods in time-series for BART and turbid sample analysis by

microscopy and biofilm collection on surfaces (sidearm for outflow from wells to collect samples of

biofouling indicative of that occurring in wells).

(b) Analysis. Light microscopy and BART methods (Section 2-8), biofilm mineralogical analysis

(X-ray diffraction for mineralogy and elemental speciation to establish fouling mineral predominant

components).

(c) Recommendation. A combination of time-series pumped sampling and BART analysis and

microscopy for filamentous iron and sulfur bacteria and FeIII-oxide minerals provides a good profile of

biofouling conditions. Routine monitoring can be limited to specific BART analyses selected to best

gauge change and periodic sampling of biofouling solids to gauge changes in type and structure (Sections

5-2 and 5-3 provide a schedule). A one-time mineralogical (XRD) and elemental analysis of solids is

useful to refine preventive maintenance chemical feed choices.

(d) Alternative. Particle counting and turbidity (both of which can be automated) can replace

biofouling sampling in systems with known biofouling characteristics.

(3) Sand content testing. Sand content may be determined by sampling with a Rossum Valve

sampler (Roscoe Moss Company 1992)

(a) At strategic intervals during well development.

(b) Averaging the results of five samples collected at incremental times during a pumping test.

NGWA (1998) provides specific recommendations. A limit of 5 ppm is achievable and optimal criterion

for well redevelopment completeness.

(c) Hydraulic monitoring using methods as described (Section 2-1).

c. Flow meter and other sensor maintenance. To ensure their usefulness in maintenance

monitoring, flow meters, and other sensors must be maintained. An open pipe insert type or nonintrusive

ultrasonic flow meter should be used to limit the effects of encrustation. Units that can be readily removed

should be specified and installed. If used, venturi flow meters (vulnerable to clogging) and sensors

(vulnerable to coating and fouling) should be periodically examined and cleaned as needed. Manual

cleaning using a mild acid detergent and rinse should suffice.
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Chapter 10

O&M Equipment Needed

10-1 Overview

There is a variety of equipment available for initial delivery of maintenance chemicals, developing wells,

and handling well pumps. These are generally described in ADITC (1997), Borch et al. (1993), NGWA

(1998), Alford and Cullimore (1999), and other publications with a focus on field equipment and

techniques appropriate to well PM. The following recommendation is not intended to be all-inclusive, but

illustrative. Such systems should not be assembled or operated without training by personnel experienced

in these practices.

10-2 Example Basic Well Maintenance Field System

a. Chemical mixing. A tank trailer should be equipped with

• 500-gal (1.9 cu m) chemical mixing tank for chemicals (acid duty, see EM 1110-1-4008).

• A second set of tanks to contain purge water for transfer to treatment. These tanks often need

to be augmented by additional portable tanks.

• Transfer pumps (in line to mix and feed to the well) and hoses with fittings to match those at

treated wellheads.

• Provision to house personal protective gear and additional safety gear such as ventilator

blowers and harnesses, MSDS, and material and instruction for neutralization and first aid,

spare parts, and basic chemical mix recipes. Also included should be a convenient means to

call for assistance such as a wireless telephone or site-frequency radio.

b. Equipment handling. A means of hoisting and handling chemical drums, pumps, and associated

pipe systems is needed. Commonly this is a conventional water well pump hoist with a maneuverable

boom, of sufficient size to hoist any object to be lifted in the well field (not < 5-ton (4535 k) hoisting

capacity).

(1) Some hoists are equipped with reciprocating beams to permit surging. These are suitable for

light surging redevelopment that is not of long duration.

(2) Alternatives include small, motorized, reversible pump puller units that apply force to pipe via

rubber tires or tracks. The motion is reversible, suitable for surging, and also permits rapid pump pulling

for service and inspection. This will save much time and effort. Rigid well pipe would be specified for

this application.

(3) Flexible well discharge pipe is coiled in the same manner as fire hose. A wheel device to run

the hose smoothly from the vertical to the horizontal orientation is needed. These are routinely supplied

by the hose supplier.

c. A development and test pumping trailer. This trailer should house:

• Development tools such as surge blocks or jets, brushes, or equipment for recirculation

cleaning.

• Spare pipe and hose.
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10-2

• Orifice weirs or flow meters.

• Water-level probes and other instrumentation and spare components such as bolts, weir

plates, and blocking.

d. Ancillary gear. Additional parts and equipment needed on hand include:

• Spare parts, pipe and hose, and pumps, which should be standardized to the extent possible.

• Air compressors, generators, etc.

• Hand tools.

• Biofouling (BART etc.) tests and portable water quality and power testing instruments for

maintenance monitoring.

• Voltage, amperage, resistance meter

These can be housed separately or on one of the field trailers or vehicles.

10-3 Provision of Maintenance Equipment

a. Large and remote projects. Sizable and more remote sites should have equipment dedicated to

the project as described in Section 10-2 and trained personnel on staff to perform maintenance. The

criterion for this threshold is when a separate well service company would devote more than three-staff

months on site per year to perform services.

b. Additional equipment and service provision options. Systems that can be serviced by qualified

commercial well service providers should do so. These companies are typically in a better position to

maintain and provide a wider range of equipment more cost-effectively than site project management.

However, particular projects, sites, and O&M contractors may have specific skills, preferences, or needs

that would result in a combination of approaches. Options include:

(1) Dedicate equipment to the site and maintain a well maintenance crew where the level of effort for well

maintenance is six staff-months per year (crew of two, dedicating three work months each).

(2) Dedicate equipment to the site and out-source well maintenance crew services (where the

level of effort for well maintenance is three to six staff-months per year). Maintaining equipment and

parts onsite ensures their availability and reduces cross-contamination potential. Onsite operational

personnel should be trained in and perform maintenance monitoring.

(3) Out-source well service entirely: Generally, where this is feasible, it is a preferred option to

avoid tying up personnel and equipment to low-frequency tasks and to take advantage of competitive

bidding. Onsite operational personnel should be trained in and perform maintenance monitoring.

c. Example costs. The costs listed in Table 10-1 are provided to offer a range of costs for well PM

planning purposes. These numbers are based on past projects and are expressed in pre-1999 dollars for the

items described in Section 10-2.
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Table 10-1. Approximate Costs of PM Equipment

Equipment Method Cost

(1) Chemical mixing. A tank trailer equipped as recommended Purchase $3,500.00

(2) Equipment handling.

(a) Standard 5-ton(4535-k)-hoisting capacity pump hoist

equipped as described.

Purchase $60,000.00

Hired (per

day)

$1,500.00

(b) Motorized, reversible pump puller unit Purchase $3,000.00

(c) Equipment to handle flexible well pipe Purchase $1,000.00

(3) Development and test pumping trailer (equipped). Purchase $5,000.00

(4) Ancillary gear.

(a) Generator (5 kW) Purchase $3,200.00

(b) Air compressor (375-cfm (1.77 m3/sec)) Rent per

week

$200.00 to $1,000

(c) Maintenance monitoring instruments and apparatus

including voltage, amperage, resistance meter

Purchase $2,000.00

(d) Recommended spare parts and equipment Purchase $5,000.00
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A-1

Appendix A

List of References and Bibliography

A-1 Required References

29 CFR 1910

29 CFR 1926

TI 814-1. Water Supply

TI 814-3. Water Distribution

TM 5-813-5. Water Supply, Water Distribution

TM 5-813-9. Water Supply: Pumping Stations

ER 385-1-92. Safety and Occupational Health Document Requirements for Hazardous, Toxic, and

Radioactive Waste (HTRW) and Ordnance and Explosive Waste (OWE) Activities

ER 1110-345-700. Design Analysis, Drawings and Specifications

EM 385-1-1. Safety and Health Requirements Manual

EM 1110-1-4000. Monitoring Well Design, Installation, and Documentation at Hazardous, Toxic and

Radioactive Waste Sites

EM 1110-1-4008. Liquid Process Piping

EM 1110-2-1914. Design, Construction, and Maintenance of Relief Wells

CEGS 02510. Water Distribution System.

CEGS 11212. Pumps, Water: Vertical Turbine

CEGS 11242. Chemical Feed Systems

CEGS 13405, Liquid Process Control

A-2 Related Publications

CEGS 02521. Water Wells

CEGS 02522. Groundwater Monitoring Wells

ER 1110-1-263. Chemical Data Quality Management for Hazardous, Toxic, Radioactive Waste

Remediation Activities

ER 1165-2-132. Hazardous, Toxic, and Radioactive Waste (HTRW) Guidance for Civil Works Projects
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A-2

a. Literature references.

Alford, G., and Cullimore, D.R. 1999. The Application of Heat and Chemicals in the Control of

Biofouling Events in Wells, CRC Press Lewis Publishers, Boca Raton, FL.

APHA-AWWA-AWRA. 1998. Standard Methods for the Examination of Water and Wastewater, 20th

ed., American Public Health Association, Washington, DC.

Australian Drilling Industry Training Committee Limited. 1997. Drilling - The Manual of Methods,

Applications and Management, Boca Raton, Lewis Publishers, 615 p.

Borch, M.A., Smith, S.A., and Noble, L.N. 1993. “Evaluation and Restoration of Water Supply Wells,”

NGWA for AWWA Research Foundation, Denver, CO.

Boulding, J.R. 1995. Soil, Vadose Zone, and Ground-Water Contamination, CRC Press Lewis Publishers,

Boca Raton, FL.

Bouwer, H., and Rice, R.C. 1976. “A Slug Test for Determining Hydraulic Conductivity of Unconfined

Aquifers with Completely or Partially Penetrating Wells.” Water Resources Research 12(3): 423-433.

Campbell, M.D. and Lehr, J.H. 1973. Water Well Technology, McGraw-Hill, New York.

Cullimore, D.R. 1993. Practical Groundwater Microbiology, Lewis Publishers, Boca Raton, FL.

Cullimore, R., and Legault. T. 1997. “Microbiological Investigations of Water Wells in the Municipal

Disrict of Kneehill, Alberta,” Droycon Bioconcepts Incorporated, Regina, Saskatchewan.

Deb, A.K., J.K. Snyder, J.J. Chelius,J. Urie, and D.K. O'Day. 1990. Assessment of Existing and

Developing Water Main Rehabilitation Practices, AWWA Research Foundation, Denver, CO.

Domenico, P.A., and Schwartz, F.W. 1990. Physical and Chemical Hydrogeology, John Wiley & Sons, .

Driscoll, F.G. 1986. Groundwater and Wells, Johnson Div., St. Paul, MN.

Ehrhardt, G., and Pelzer, R. 1992. Wirkung von Saugstromsteuerungen in Bohrbrunnen. bbr - Heft 10/92.

(Function of in-flow rectification in bore wells). English translation available, Kabelwerk Eupen AG,

Eupen, Belgium.

Gariboglio, M.A. and S.A. Smith. 1993. Corrosión e incrustación microbiológia en sistemas de captación

y conducción de agua: aspectos teóricos y aplicados. Serie Investigaciones Aplicadas, Argentine Consejo

Federal de Inversiones, Buenos Aires, Argentina, 99 pp.

Helweg, O.J., Scott, V.H., and W.C. Scalmanini. 1983. Improving Well and Pump Efficiency, AWWA,

Denver, CO.

Howsam, P., Misstears, B., and Jones, C. 1995. “Monitoring, Maintenance and Rehabilitation of Water

Supply Boreholes,” Report 137, Construction Industry Research and Information Association, London,

U.K., 113 pp.
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A-3

Hvorslev, M.J. 1951. “Time Lag and Soil Permeability in Ground-Water Observations,” Bulletin No. 36,

U.S. Army Corps of Engineers, Waterways Experiment Station, Vicksburg, MS.

Kissane, J.A., and Leach, R.E. 1993. “Redevelopment of Relief Wells, Upper Wood River Drainage and

Levee District, Madison County, Illinois,” Technical Report REMR-GT-16, U.S. Army Corps of

Engineers, Waterways Experiment Station, Vicksburg, MS.

Kruseman, G.P., and Ridder, N.A. 1994. Analysis and Evaluation of Pumping Test Data, ILRI

Publication 47, International Institute for Land Reclamation and Improvement, Wageningen, The

Netherlands.

Labadie, J.W., and Helweg, O.J. 1975. “Step-Drawdown Test Analysis by Computer,” Groundwater

13(5): 438 - 444.

Leach, R.E., Mikell, A., Richarson, C., and Alford, G. 1991. “Rehabilitation of Monitoring, Production

and Recharge Wells,” , CETHA-TS-CR-91077, U.S. Army Toxic and Hazardous Materials Agency,

Aberdeen Proving Grounds, MD, pp 623-646.

Little, B.J., Wagner, P.A., and Mansfield, F. 1997. Corrosion Testing Made Easy: Microbially Induced

Corrosion, NACE International, Houston, TX.

McLaughlan, R.G. 1996. “Water Well Deterioration,” Technology Transfer Publication 1/96, National

Centre for Groundwater Management, Sydney, Australia, 99 pp.

MINTEQ (U.S. EPA).Center for Exposure Assessment Modeling (CEAM), Athens, GA 30605-2700).

National Ground Water Association. 1998. Manual of Water Well Construction Practices, Westerville,

OH.

Nuzman, C.E. 1989. “Well Hydraulic Flow Concept,” Recent Advances in Ground-Water Hydrology,

American Institute of Hydrology, Minneapolis, MN.

Parkhurst, D.L., Plummer, L.N., and Thostenson, D.C. 1982. “BALANCE -- A Computer Program for

Calculating Mass Transfer for Geochemical Reactions in Ground Water,” Water Resources Investigations

82-14, U.S. Geological Survey, Reston, VA.

Powers, J.P. 1992. Construction Dewatering, Wiley-Interscience, New York.

Roscoe Moss Company. 1992. Water Well Development, Wiley-Interscience, New York.

Smith, S.A. 1992. Methods for Monitoring Iron and Manganese Biofouling in Water Supply Wells,

AWWA Research Foundation, Denver, CO (96 pp).

Smith, S.A. 1995. Monitoring and Remediation Wells: Problem Prevention, Maintenance and

Rehabilitation, CRC Lewis Publishers, Boca Raton, FL (183 pp).

Smith, S.A. 1996. “Monitoring Biofouling in Source and Treated Waters: Status of Available Methods

and Recommendations for Standard Guide,” Sampling Environmental Media, ASTM STP 1282, J.H.

Morgan, ed., American Society for Testing and Materials, West Conshohocken, PA, pp. 158-175.
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A-4

Sutherland, D.C., Howsam, P., and Morris, J. 1994. “The Cost-Effectiveness of Monitoring and

Maintenance Strategies Associated with Groundwater Abstraction - A Methodology for Evaluation,”

ODA Project Report 5478A, Silsoe College, Silsoe, Bedford, U.K.

Truesdell, A.H., and Jones, B.F. 1974. “WATEQ, A Computer Program for Calculating Chemical

Equilibria in Natural Waters,” USGS Journal of Research 2(2): 233-248.

Tuhela, L., Smith, S.A., and Tuovinen, O.H. 1993. “Flow-Cell Apparatus for Monitoring Iron Biofouling

in Water Wells,” Groundwater 31:982-988.

Walton, W.C. 1996. Aquifer Test Analysis with WINDOWS Software, Boca Raton, Lewis Publishers, 301

pp.

b. Internet. The internet (specifically the World Wide Web) contains sources of information not

necessarily published. The following were consulted, and should remain stable and available for

reference.

http://www.arcc.net/ Alford, Rogers, Cullimore Concept Inc. information on BCHT well

remediation process.

http://www.groundwatersystems.com Smith-Comeskey Groundwater Science well maintenance

and rehabilitation information area.

http://www.ngwa.org National Groundwater Association (literature database).

http://www.dbi.sk.ca Droycon Bioconcepts (University of Regina) information on biological

well clogging and deterioration.

c. Concensus Standards. These are a partial listing of AWWA and ASTM Test Methods,

Standard Tests, and Standard Guides relevant to this work. They are offered as references for procedures

to consult and not necessarily as authoritative.

(1) AWWA.

AWWA B300, Chlorine.

AWWA B303, Potassium Permanganate.

ANSI/AWWA C503. Wet Barrel Fire Hydrants.

ANSI/AWWA C657-97. Well Chlorination.

ANSI/AWWA C654-97. Disinfection of Wells.

(2) ASTM.

A589-95a Standard Specification for Seamless and Welded Carbon Steel Water-Well Pipe.

D421 Standard Practice for Dry Preparation of Soil Samples for Particle-Size Analysis and

Determination of Soil Constants.

D422 Standard Test Method for Particle-Size Analysis of Soils.

D 932 Test Method for Iron Bacteria in Water and Water-Formed Deposits.

D 4043-96 Standard Guide for Selection of Aquifer-Test Method in Determining of Hydraulic

Properties by Well Techniques.

D 4044-96 Standard Test Method for (Field Procedure) for Instantaneous Change in Head (Slug)

Tests for Determining Hydraulic Properties of Aquifers.

D 4050 Standard Test Method (Field Procedure) for Withdrawal and Injection Well Tests for

Determining Hydraulic Properties of Aquifer Systems.
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A-5

D 4104 Standard Test Method (Analytical Procedure) for Determining Transmissivity of

Nonleaky Confined Aquifers by Overdaming Well Response to Instantaneous Change in Head (Slug

Test).

D 4750 Test method for determining subsurface liquid levels in a borehole or monitoring well.

D 5088 Standard practice for decontamination of field equipment used at non-radioactive waste

sites.

D 5092 Standard practice for design and installation of ground-water monitoring wells in granular

aquifers.

D 5472 Standard test material for determining specific capacity and estimating transmissivity at

the control wells.

D 5521 Standard guide for development of ground water monitoring wells in granular aquifers.

D5753-95 Standard Guide for Planning and Conducting Borehole Geophysical Logging.

D5786-95 Standard Practice for (Field Procedure) for Constant Drawdown Tests in Flowing

Wells for Determining Hydraulic Properties of Aquifer Systems.

D5903-96 Standard Guide for Planning and Preparing for a Groundwater Sampling Event.

D5911-96 Standard Practice for Minimum Set of Data Elements to Identify a Soil Sampling Site.

D 5978 Standard Guide for Maintenance and Rehabilitation of Ground-Water Monitoring Wells.

D5979-96 Standard Guide for Conceptualization and Characterization of Ground-Water

Systems.

D5980-96 Standard Guide for Selection and Documentation of Existing Wells for Use in

Environmental Site Characterization and Monitoring.

D6034-96 Standard Test Method (Analytical Procedure) for Determining the Efficiency of a

Production Well in a Confined Aquifer from a Constant Rate Pumping Test.

D6089-97 Standard Guide for Documenting a Ground-Water Sampling Event.

(3) NSF

ANSI/NSF Standard 61 Drinking Water System Components -- Health Effects. NSF International, Ann

Arbor, MI.
EP 1110-1-27

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B-1

Appendix B

Explanations of Abbreviations and Terms

(a) Attachment -- the act of a bacteria or a biocolloid becoming fixed to a surface. Growth may then

follow leading to the formation of biofilms.

(b) BART -- a patented biological activity reaction test biodetection system which can be customized to

determine the aggressivity and composition of selected consortia of microorganisms.

(c) BCHT -- a patented blended chemical heat treatment system which can be applied to rehabilitate

biofouled wells and systems by a three-step technology.

(d) Biocides -- specific chemicals or compounds which have a deleterious impact on the targeted

organism.

(e) Biodegradation -- the act of degrading a molecule to one or more smaller molecules by biochemical

mechanisms (e.g., enzyme action).

(f) Biofilm -- a slime-like matrix composed of extracellular polymer substances (EPS) within which a

consortium of microorganisms flourish. These biofilms may either grow over surfaces, or occupy voids in

a porous medium.

(g) Biofouling -- any deleterious event in which a definable biological activity causes a deterioration in an

engineered or natural process or system. Deleterious effects range from clogging, corrosion, and plugging

to gas production and bioaccumulation.

(1) Bioaccumulation -- any buildup of biomass, extracellular products and associated mineral and

particulate matter associated with biofilm formation and development.

(2) Biocorrosion -- biologically induced or accelerated corrosion (equivalent term: microbially

induced corrosion, MIC)

(h) Biomass -- the mass of a living entity which may be expressed as either the wet or dry weight.

Biomass may furthermore be given as the total mass including all associated mass, or as the viable mass

which would include just the viable cells. In biofilms, the total mass would relate to the total weight of the

"slime" as such (which has potential application in planning maintenance treatment) while the viable mass

would include just the mass directly associated with the living cells.

(i) Clogging -- the generation of a mass which interferes with physical functioning (e.g., hydraulic

conductivity) of a porous medium (e.g., gravel pack, sand filter) or transmitting capacity of a device or

pipe. Clogging can be formed through the maturation of biofilms fouling the media and may become

complex in structure.

(j) Consortium (plural: consortia) (synonym: community) -- communities or associations, often

interdependent, of microorganisms.

(k) Corrosion -- the process of erosive deterioration in the physical form and engineered characteristics of

a structure. These processes frequently involve electrolytic and/or corrosive chemical (e.g., acids) effects

which are sometimes mediated by microbial activities (biocorrosion or microbially induced corrosion). It

has been observed that corrosive pitting can form directly under biofilms.
EP 1110-1-27

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B-2

(l) Depositional biofouling -- biofouling resulting in the deposition of slime, metal oxide, and other

material on a surface or in a porous medium (bioaccumulation).

(m) Disinfection -- the act of destroying by chemical and/or physical means microorganisms that are

causing an undesirable infestation at a site. It does not mean that all microorganisms are killed; it means

that there is a selective action.

(n) Encrustation -- a relatively solid plate-like or crystalline structure coating a surface. It appears to be

chemical in nature due to the hardness of the structure. Often brittle (when dry) or plastic (when wet), the

organic content is usually relatively small.

(o) Extracellular polymer substances (EPS or ECPS) -- a general term for exopolymers produced by many

microorganisms, typical carbohydrate based, outside the cell (equivalent term, glycocalyx).

(p) Heterotrophic microorganisms -- those microbes which obtain their energy from the breaking down of

organic (carbon-containing) material. Some of these microbes are very specialized (e.g., cellulose

degraders) while others can utilize a variety of organic compounds.

(q) Iron oxidizing bacteria (IOB) -- those bacteria able to oxidize iron by any means from a reduced form

of iron (ferrous form) to an oxidized (ferric) state. Some authorities define genuine IOB as those

chemolithotrophs that oxidize iron metabolically.

(r) Iron reducing bacteria -- those bacteria which are able to reduce iron by any means from an oxidized

form (ferric) to a reduced (ferrous) state.

(s) Iron related bacteria (IRB) -- all of those bacteria which are able to accumulate iron in another form

beyond that for basic metabolic functioning. These accumulated iron compounds generally collect within

the slime (EPS) around the cells and gradually harden (crystallize) over time.

(t) Maintenance monitoring -- as part of a preventive maintenance strategy, monitoring of system

parameters to detect indicators of deteriorating conditions.

(u) Maintenance treatment -- a cleaning treatment applied in a preventive or proactive manner, typically

before performance of the system is impaired.

(v) Microbially induced corrosion -- see Biofouling.

(w) Preventive Maintenance (PM) -- a management strategy of ongoing monitoring and preventive repair

and replacement of components of a system or process to prevent or delay recognized deterioration.

(x) Rehabilitation -- the returning of a well or other system to its original specified state by the application

of suitable treatments.

(y) Redox (Eh) -- oxidation-reduction potential (ORP). Oxidation and reduction reactions mediate the

behavior of many chemical constituents in the environment. This is a relative scale of the intensity of

electron donor activity, as measured between a suitable reference electrode and an inert indicator

electrode, and typically expressed in terms of Eh volts or millivolts (plus or minus) in relation to the

reference.

(z)Redox fringe -- a term applied to transition zones that develop in formations around working wells

where the predominant ion state of metal changes from the reduced, dissolved form (e.g., MnII, FeII) to
EP 1110-1-27

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B-3

the oxidized, low-solubility form (MnIV, FeIII). This zone tends to be important as a buildup point for

clogging biofouling.

(aa) Shock treatment -- the application of a higher than normal chemical dose in order to maximize the

effectiveness of the treatment being applied.

(bb) Slime -- a surface growth on, or originating from, a surface which may be jelly-like in form

(typically EPS). Such slimes usually include various microorganisms and can act as sites for the

bioaccumulation of various chemicals.

(cc) Slime forming bacteria -- bacteria which produce slimes (from EPS), but do not necessarily (or

incidentally) accumulate iron within these slimes (BART acronym “SLYM” refers to these).

(dd) Sloughing -- the act of a slime, for whatever reasons, breaking up and releasing particles (from the

slime) to the water passing over the slime.

(ee) Substrate (biological) -- conceptually equivalent to available organic carbon. Also used for surfaces

on which biofilms attach.

(ff) Sulfate (or sulfur) reducing bacteria (SRB) -- anaerobic bacteria able to reduce sulfate (and some

other sulfur species) to hydrogen sulfide. This event may initiate electrolytic corrosion and/or rotten egg

taste and odors in water.
EP 1110-1-27

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C-1

Appendix C

Experience Basis and Maintenance Treatment Example

C-1. Case Histories of Well Maintenance Activities

Case histories are illustrative of possible problems and how they were handled elsewhere. A number of

water supply system case histories are summarized in Smith (1992), Borch, Smith, and Noble (1993), and

Cullimore (1993) among others. These are illustrative of the worldwide distribution of problems of wells,

and, in particular, those associated with Fe, Mn, and S biofouling, and how they have been addressed.

Several other geotechnical and environmental-studies case histories are summarized in Smith (1995) and

Alford and Cullimore (1999) and are the basis for the following.

(1) Problems associated with wells are largely the same all over the world.

(2) Lack of planning and adequate response to deterioration problems of wells results in reduced

performance of wells and water collection and distribution systems.

(3) The economic impacts of this deterioration can be significant, but are only now being

quantified adequately in the water supply setting (e.g., Sutherland, Howsam, and Morris 1994), but hardly

at all in the HTRW remediation field. For water supply wells, Sutherland, Howsam, and Morris (1994)

estimate that 40% of wells worldwide are operating inefficiently. It is estimated that $100 million is

annually spent on well and well pump rehabilitation in North America.

(4) Preventive actions useful in limiting the effects of biofouling (as documented in open

literature) have not been widely applied in the planning of ground water supply and control projects to

date.

(5) Design and operations poorly matched to the aquifer being pumped (e.g., choice of corrodible

materials or excessive pumping) aggravate environmental well deterioration causes.

(6) Adverse well deterioration effects on the reliability of ground water quality samples have been

documented.

(7) Wells operating under vacuum and anaerobically exhibit fewer clogging symptoms.

(8) Injection of biocides has largely been ineffectual in solving the immediate well problems.

They almost always fail to prevent a recurrence of problems, although recurrence of performance decline

may be significantly delayed.

(9) Where attention to microbial fouling potential (or the symptoms of such fouling) results in the

institution of a preventive maintenance program, biofouling-related problems can be controlled (see

additional case histories summarized in this section). However, programs have to be revised in response

to experience with a well field over time.

(10) New well construction may serve to temporarily avoid recurrence of a problem. However,

current experience is demonstrating that clogging, biofouling, and Fe/Mn/S transformations may extend

several meters away from wells with existing problems. The performance problems of the former wells

cannot be considered solved with new construction. The problems are likely to recur with the new wells

unless a maintenance program is implemented.
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C-2

C-2. Maintenance Treatment for Wells: Basic Procedure

The procedure described below is an invasive maintenance treatment procedure that has proven to be

generally effective in stemming biofouling-related decline of well system performance on HTRW sites.

Note that some well situations will not require Steps 1 and 2, but most do at some point. An approach

similar to this has been approved at a Superfund site location in New Hampshire.

1. Detach and remove the installed well pump and other equipment such as water-level gauge transducers.

Set aside, service, or replace components as needed, and clean in preparation for re-installation. NOTE: It

is better to remove the pump in most situations; however, if the well pump is on the bottom, or if the well

is specially equipped, the pumping system can be used for circulation.

2. Brush casing and screen and bail or pump out to remove settled and surface-attached debris in the well.

Brushes should be properly sized and designed to abrade surface deposits, but not to score or gouge

casing or screen materials. These are often specially shop-fabricated for specific well applications.

3. (Optional): Conduct a downhole TV survey to assess damage or material changes. Conduct the survey

before brushing is started.

4. Mix a solution for treatment in clean (sediment-free) chemical-resistant tanks: In a volume of clean

(potable) water three times that of the calculated volume of the well screen (including the gravel pack

volume often makes for an excessively large treatment volume), add sufficient nonphosphorus anionic

wetting agent to make a 1% solution and mix, add sufficient industrial-grade glacial (87%+) acetic acid

sufficient to make a 12% solution (range 10 to15 %), and amend with sufficient clean, industrial grade

sulfamic acid to adjust the pH to < 2 (mix well to dissolve). Oxalic or citric acids can be used in place of

acetic acid for heavy iron oxide encrustation in waters with less than about 120 to150 mg/L total

hardness. Adjust pH as needed by adding acid. NSF International listed products are available for some of

these applications.

NOTES:

Always add acids to water and not vice-versa. While relatively safe to handle, all the chemicals specified

can cause chemical burns of skin, eyes, and respiratory tissues if mishandled. Anyone handling well

treatment chemicals should have specific training for this purpose, and equipment should be supplied to

minimize the potential for accidental spills or human exposure.

Both acetic acid and sulfamic acid are readily available from conventional chemical supply sources.

While costly in relation to some acid products, acetic acid has the advantage of having some disinfection

properties, is not highly reactive with metals and metal oxides (in contrast to mineral acids), and is the

best detergent acid. Sulfamic acid is inexpensive and a readily transportable and storable solid. Both

acetic and sulfamic acids are Class 55 detergents (nonhazardous), which adds flexibility in transport.

Highly concentrated acetic acid solutions freeze below about 12o

 C (~ 55o F) and should be kept above

this temperature prior to mixing. Dilute treatment solutions have much lower freezing temperatures far

below most ambient ground water temperatures. Where this may be critical (as in application under very

cold surface conditions into near-freezing ground water), those conducting treatment should calculate the

freezing points of dilute solutions. Hot water can be mixed with acetic acid to avoid freezing, or more

dilute solutions can be used.

Constant rate pumping tests and slug tests (in which an instantaneous charge of water or a solid object is

introduced into a well)
EP 1110-1-27

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C-3

All surfaces potentially in contact with cleaning solution should be nonreactive with its components.

Chemical-resistant hose, stainless steel, PVC, and high density polyethylene (HDPE) plastics in tanks,

fittings, and pumps will provide good service.

5. After batch mixing, tremie into the screen zone by gravity from the bottom up across the screen

surface. Apply very slowly (~ 10 gpm ( ~ 0.0379 cu m/min)) through a 1- to 2-in. ( 2.54- to 5.08-cm) -

diameter pipe made of nonreactive materials.

6. Surge in place and leave overnight (12 to 24 hr). Do not leave in place more than a weekend.

NOTE: Surge tool and applications of conventional ground water technology for well development

surging apply to HTRW well cleaning. For example, surge blocks should have size and weight to permit a

1- to 2-ft/sec (0.3- to 0.6- m/sec) fall.

VARIATION (pump in place): Remove the well cap, disengage pitless adapter, and pull up pumping

discharge assembly to surface. Use a reversible friction pump puller to move the pump slowly up and

down to provide a surging action. Pump at a low rate during surging, recirculating back down the well

(monitor pH - treatment is finished if pH rises above about 5 or if water clears). Note: Watch for lockup

and stop immediately if it occurs.

7. If satellite wells are installed around a pumping or injection well for treatment application (highly

recommended), treat each 2- to 4-in (5.08- to 10.16-cm) -diameter well with a solution as in step 4, but

six times the satellite well's screen diameter. Surge in place and leave overnight (see step 6).

8. For both the target and satellite wells, sound wells to determine depth and safety to insert development

tools. Surge and pump to containment and necessary pretreatment prior to release to water/wastewater

treatment. Release water should pass through the site's remediation treatment facility prior to release to

the open environment.

NOTES:

Know the specific release and treatment requirements of the jurisdiction, project, and site.

Check pH and treat as needed to within 1 pH of background (pH 6.5 to 8.5 for wastewater treatment

plants).

Tanks for containment should be sufficient in size to handle the expected discharge water volume

requiring treatment without shutting down development. The system for neutralizing should permit

continuous and not batch treatment.

If site remedial treatment is digestive, expect a radical increase in BOD and COD. Expect and plan for

pretreatment for a large increase in mineral and encrustation-debris solids content.

9. Continue surging until a set standard for clarity is met (standard set realistically based on site

experience. Some standards used are < 5 NTU turbidity, < 5 ppm sediment, and a predetermined percent

recovery of specific capacity. Sound wells periodically and remove accumulated debris. Examine to

determine the nature of solids (filter pack? formation?). If excessive filter pack is brought in, examine

with downhole TV to determine if a screen or casing breach has occurred.

NOTE: This can be a lengthy process, especially if wells were not developed sufficiently when installed,

or during remediation attempts. Frequent maintenance treatments should reduce the necessary
EP 1110-1-27

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C-4

development time considerably.

10. Reassemble, install, and test the pump and in-well instrumentation and return to service.

11. Benchmark biofouling and performance indicators using methods suggested.

12. Clean and make necessary repairs to treatment equipment.

C-3. Treatments for Heavily Impacted Wells

a. While the intended scope of this EP is the maintenance of well system performance, it is recognized

that O&M personnel will usually find themselves in the situation of rehabilitating wells and systems that

have deteriorated in performance. Rehabilitative treatments have many similarities to maintenance

treatments such as the example outlined in paragraph C-2. Such treatments are summarized in Driscoll

(1986), Borch, Smith, and Noble (1993), Cullimore (1993), Smith (1995). One such treatment

summarized in Alford and Cullimore (1999) focuses on HTRW remediation applications.

b. Rehabilitation treatments outlined in these publications typically can be applied using adaptations of

conventional ground water technology equipment. In addition, well rehabilitation has a number of

specialty tool, equipment, supply, and service vendors. An attempt has been made to offer information on

and Internet links to sites on well rehabilitation from the "Groundwater Science" website

<http://www.groundwatersystems.com>.
D-1

Appendix D

Examples of Logs, Checklists, Calculations.

a. General: The logs and checklists in this appendix are provided as examples. Projects and

service providers typically have existing forms that they use. Records can be kept in any convenient paper

and/or electronic form with redundancy. Field checklists for well maintenance treatment should include at

least the information asked for in the example. It may be useful to divide checklists into specialty topics,

for example, separate pumping test, mechanical development, chemical dosing, and chemical treatment

forms. The pumping test analysis diagrams provided are generated from a pumping test analysis computer

program.

b. Calculations: A copy of Appendix 11.L of Driscoll (1986) is provided for calculation of

volumes in well casings and screens. Generally, screen pipe size volume x 1.5 is a safe volume figure to

use for treatment chemicals in maintenance. To calculate acid in pounds:

(1) Dry: well volume (WV) x 8.3 (convert water volume to lb) x (% acid/%active acid).

Example for a 10 % solution: 110 gal x 8.3 x (0.10/0.75) = 121.73 lb

(2) Liquid (gal): (WV x % acid)/(% available acid in solution).

Example for a 10 % solution from 84 % available acid stock:

110 gal x 0.10/0.84 = 13 gal of stock chemical

Note: Chemical suppliers may list acid solutions by weight. Suppliers can provide the specific gravity or

weight per volume of the stock solution needed.

c. Plates D-1 through D-13 are examples of logs and checklists to help collect and organize data.

The checklists are presented as aids but are not all-inclusive since each site has site-specific data.

D-1 Extraction Well Pumping Test Data Sheet

D-2 Chart of Step-Drawdown Test Data

D-3 Step-Drawdown Test Data, April 6, 1999, Hantush-Bierschenk Analysis

D-4 Step-Drawdown Test Data, April 6, 1999, Estimated Aquifer and Well Loss

D-5 Volume of Water in Casing or Hole (Appendix 11.L, Driscoll 1986)

D-6 Extraction, Injection, and Monitoring Wells Maintenance Checklist

D-7 Well Information Recording Sheet

D-8 Extraction Well Cleaning Data Sheet

D-9 Extraction Well Development Data Sheet

D-10 Well Service Record Sheet (blank)

D-11 Well Service Record Sheet (completed example)

D-12 HTRW Drilling Log (blank)

D-13 HTRW Drilling Log (completed example)
EP 1110-1-27 EXTRACTION WELL PUMPING TEST DATA

27 Jan 00 CONTRACT DACW45-92-C-0156

OTT/STORY/CORDOVA SUPERFUND SITE

NORTH MUSKEGON, MICHIGAN

WELL: DATE:

DRAWDOWN AND FLOW MEASUREMENTS

TIME ELAPSED

TIME (min)

METER

READING

(gal)

DEPTH TO

WATER (ft)

FILTER PACK

DEPTH TO

WATER (ft)

INNER REHAB

WELL

DEPTH TO

WATER (ft)

SATELLITE

WELL

DEPTH TO

WATER (ft)

SATELLITE

WELL

DEPTH TO

WATER (ft)

ADJACENT

WELL

OTHER DATA

TOTAL PUMPED (gal) TOTAL TEST DURATION (min) AVERAGE FLOW RATE (gpm) FINAL DRAWDOWN (ft)

SPECIFIC CAPACITY 

(gpm/ft)

FLOW METER

IDENTIFICATION NUMBER

WELL WATER pH AFTER

TEST

FINAL WATER TEMP. (°F)

WELL DEPTH BEFORE

TEST (ft)

WELL DEPTH AFTER TEST (ft) SAND IN DISCHARGE ? (YES

or NO)

SAND CONCENTRATION

(ppm)

AS-BUILT SPECIFIC

CAPICITY (gpm/ft)

AS-BUILT WATER TABLE (ft.

msl)

DATE INSTALLED

(ORIGINAL)

REMARKS

 _____________________________ ___________________________________________________

 DATE SIGNATURE OF QUALITY CONTROL REPRESENTATIVE

Plate D-1
EP 1110-1-27

27 Jan 00

Plate D-2
EP 1110-1-27

27 Jan 00

Plate D-3
EP 1110-1-27

27 Jan 00

Plate D-4
EP 1110-1-27

27 Jan 00

Volume of Water in Casing or Hole*

Diameter of

casing or hole

(in)**

Gallons per foot

of water

column**

Cubic feet per

foot of water

column**

Liters per meter

of water

column**

Cublic meters

per meter of

water column**

2 0.163 0.0218 2.024 2.02 x 10 -3

4 0.653 0.873 8.11 8.11 x 10 -3

5 1.02 0.1364 12.67 12.67 x 10 -3

6 1.469 0.1963 18.24 18.24 x 10 -3

7 2 0.2673 24.84 24.84 x 10 -3

8 2.611 0.3491 32.43 32.43 x 10 -3

10 4.08 0.5454 50.67 50.67 x 10 -3

11 4.937 0.66 61.31 61.31 x 10 -3

12 5.875 0.7854 72.96 72.96 x 10 -3

14 8 1.069 99.35 99.35 x 10 -3

16 10.44 1.396 129.65 129.65 x 10 -3

18 13.22 1.767 164.18 164.18 x 10 -3

20 16.32 2.182 202.68 202.68 x 10 -3

24 23.5 3.142 291.85 291.85 x 10 -3

34 47.16 6.305 585.68 585.68 x 10 -3

36 52.88 7.069 656.72 656.72 x 10 -3

* After Driscoll (1986) Appendix 11.L.

** 1 in = 25.4 mm.

 1 gallon = 3.785 L.

 1 meter = 3.281 ft.

 1 gallon water weighs 8.33 lb = 3.785 kg.

 1 L water weighs 1 kg = 2.205 lb.

 1 gallon per ft of depth = 12.419 L per ft of depth

 1 gallon per m of depth = 12.419 x 10 -3

cubic m per m of depth.

Plate D-5
EP 1110-1-27

27 Jan 00

EXTRACTION, INJECTION, AND MONITORING WELLS

12/16/99

Introduction

This checklist is meant to evaluate the adequacy of maintenance of the extraction and monitoring wells on

site. The adequacy of the extraction system should be evaluated using the Ground Water Extraction

Subsurface Performance Checklist. The adequacy of the monitoring network should be evaluated using the

Environmental Monitoring Checklist.

References

EM 1110-1-4000 Monitor Well Design, Installation, and Documentation at HTRW Sites

ETL 1110-1-201 Ground Water Extraction

Current Operating Conditions and/or Configuration

Record any deviations from as-builts ____________________________________________________

___________________________________________________________________________________

___________________________________________________________________________________

Adequacy of Operations and Maintenance:

Wellheads Protected from Standing Surface Water? ____

Is there settlement around the well (i.e. due to inadequate compaction or aquifer consolidation)? ____

Above-ground wellheads painted and clearly labeled? ____

Vault covers and vaults in good repair and clearly labeled? ____

Wellhead enclosures painted, well maintained, and clearly labeled? ____

Are concrete pads around the well in good condition? ____

Has there been physical damage to the well? ____

Is there evidence for frost heave/jacking of the protective casing or well casing? ____

Is there a regular program for evaluating the performance of the well (check specific capacity and

accumulated sediment)? ____

Is there evidence of degradation of well performance? ____

What was the original specific capacity and how does it compare to the current capacity?

Is there a regular program to evaluate down hole conditions (e.g., camera survey) ____

Have BART tests or other bacteriological tests been utilized to evaluate biofouling? ____

For injection wells only, has the treated/injection water been tested for the potential to cause inorganic

precipitation? ____

Is there a regular well maintenance program? ____

If so, What is the well maintenance protocol: _________________________________________

___________________________________________________________________________________

Can the prescribed well maintenance be carried out given the layout of the well and the available personnel

and equipment? ____

When was the well last developed and when will it be redeveloped? ____

Is there evidence of well or drop pipe corrosion? ____

Is there an up-to-date logbook for recording performance & maintenance for each extraction well? ____

How many gallons of water has the well pumped since it was installed? ____

Is there a maintenance schedule for the pump and how is it documented? ____

Has there been excessive pump wear noticed due to sediments? ____

Are all of the flow meters/totalizers in good working order? ____

Is there an inventory of appropriate spare parts for the pumps and related equipment? ____

Is there evidence suggesting the lines between the wells and the plant are occluded? ____

Sheet 1 of 2

Plate D-6
EP 1110-1-27

27 Jan 00

Problems to Watch For

Well siltation (fine material enters the well and settles to the bottom, ultimately occluding the screen)

Solution: periodic sounding of the well and bailing the sediment when it reaches a certain height above the

bottom cap.

Well encrustation or fouling (common problem, scale or biological growth forms on well screen, reducing

open area and increasing water entrance velocities, typically manifested by reduced specific capacity of the

well). Solution: periodic rehabilitation when the specific capacity decreases to a predetermined level

according to a protocol appropriate for the cause of the reduced capacity.

Physical damage to the well due to frost, vehicles, vandalism (can limit or prevent use of the well,

compromise integrity of the well and allow contaminated surface water to migrate to the subsurface).

Solution: inspection and repair. Severe damage can require well replacement. Damaged well must be

decommissioned in accordance with state requirements.

Excess sand/turbidity production even after extensive redevelopment (due to corrosion, inadequate design

of filter pack and/or screen). Solution: well replacement. Other alternatives (e.g., selective pressure

grouting of an affected zone or blank casing / small-slot screen inserts) could be considered for very

expensive/deep wells but may not result in adequate well performance.

Process Monitoring

Not Applicable

Alternatives for Possible Cost Savings

Extraction Wells:

Consider the following alternative

Extraction trenches (have increased intake area, lower entrance velocities.

Treatment walls or wells (see Ground Water Extraction Technology checklist)

Monitoring Wells

Buried Sensors

SeaMIST

Direct Push Probes

Sheet 2 of 2

Plate D-6
EP 1110-1-27

27 Jan 00

Plate D-7
EP 1110-1-27

27 Jan 00

EXTRACTION WELL CLEANING DATA

CONTRACT DACW45-92-C-0156

OTT/STORY/CORDOVA SUPERFUND SITE

NORTH MUSKEGON, MICHIGAN

 EXTRACTION WELL INITIAL DEPTH (FT) AS-BUILT DEPTH (FT) DATE

ACID TREATMENTS

ACID BLEND

BACKGROUND WATER TEMP

(• F)

BACKGROUND WATER pH

STARTING ACID END 10’ ZONE

ZONE WORK

PERFORMED

START

TIME

END

TIME

START

WELL

DEPTH

(FT)

ACID

BLEND

VOL.

(GAL)

pH TEMP.

(• F)

PRES

S

(PSI)

pH WELL

DEPTH

(FT)

TEMP.

(• F)

REMARKS

_____________________________ ___________________________________________________

 DATE SIGNATURE OF QUALITY CONTROL REPRESENTATIVE

Plate D-8
EP 1110-1-27

27 Jan 00

EXTRACTION WELL DEVELOPMENT DATA

CONTRACT DACW45-92-C-0156

OTT/STORY/CORDOVA SUPERFUND SITE

NORTH MUSKEGON, MICHIGAN

EXTRACTION WELL INITIAL DEPTH (FT) AS-BUILT DEPTH (FT) DATE

ACID TREATMENTS

ACID BLEND

BACKGROUND WATER TEMP (°F) BACKGROUND WATER pH

SURGING DATA

ZONE WORKED

PERFORMED

START TIME END TIME STARTING DEPTH

(FT)

ENDING DEPTH

(FT)

ENDING pH

WELL DEPTH BEFORE (FT) WELL DEPTH AFTER (FT) FINAL WATER pH

REMARKS

_____________________________ ___________________________________________________

 DATE SIGNATURE OF QUALITY CONTROL REPRESENTATIVE

Plate D-9
EP 1110-1-27

27 Jan 00

WELL SERVICE RECORD

Job

designation

Date started

Customer Date

finished

Job address City State

Work

performed

Personnel

 Checklist

 Surface facility

 inspection

 Pump

 test

 Pump removal,

 service, reset

 Well

pumping 

test (pre-)

Type of

test::

 Mechanical

well 

redevelopment

Type: Well

pumping 

test (post)

Type of

test:

 Chemical well 

 treatment

Type:

 Additional 

 service

Type:

Describe

equipment used

Well: ____________ Dimensions and capacities

Construction

date

Well

Depth

Casing diameter

Original yield Pump

type

Screen slot size

(state units)

Current yield Casing

material

Screen diameter

Original Q/s Screen

material

Screen length

Q/s before

action

(@ what gpm)

Q/s after

action @

Filter pack

description

Activity

Action description Time interval Dimensions Notes/comments:

Sheet _1_ of ___

Signature and date (print name and title):

Plate D-10
EP 1110-1-27

27 Jan 00

WELLS CONTRACTING LP Groundwater Contractors

345 Pumphoist Circle/St. Joseph, OH 46001/740-555-5555

WELL SERVICE RECORD

Job designation Oil City routine maintenance Date started 7/22/1999

Customer Oil City Properties LLC Date finished 7/24/1999

Job address 666 Lucky Ln City Sweetwater State WV

Work performed Scheduled well cleaning and pump service

Personnel Jeff Friederhorst, foreman; Ken Wells, journeyman

 Checklist

 Surface facility

 inspection

 Pump

 test

 Pump removal,

 service, reset

 Well

pumping 

test (pre-)

Type of

test::

 Mechanical

well 

redevelopment

Type: Surge and pump Well

pumping test

(post)

Type of

test:

Specific capacity

 Chemical well 

 treatment

Type: Acetic + CB4 10 % sol.

 Additional 

 service

Type: Fixed faulty controller

Describe

equipment used

Surge block w/ pump

Well: South pumping array PW-15 Dimensions and capacities

Construction date 5/1990 Well Depth 95 ft Casing diameter 8 _

Original yield 127 gpm Pump type Goulds 50L Screen slot size

(state units)

0.040 in

Current yield 118 gpm Casing

material

PVC Screen diameter 6 _

Original Q/s 13 gpm/ft Screen

material

315 stainless Screen length 20.5 ft

Q/s before action

(@ what gpm)

10 gpm/ft Q/s after

action @

12 gpm/ft Filter pack

description

3-in annular r.

0.060 silica

Activity

Action description Time interval Dimensions Notes/comments:

Checked equipment,

power

13:15-13:45 All nominal

Checked records, talked

to site supervisor

13:45-14:00 Nothing new

Pulled pump 14:00-14:30 45 ft of line Covered in iron bacteria

Steam clean pump 14:40-16:00 Cleaned up good

Run in surge 14:40-15:00 In screen

Run block 15:00-16:00 5 ft interval 7 min per section

Shut down

Start up surge 7:30

Mix chemicals 7:40-9:00 60 gal H2O, 7 gal 84% acetic + .5 gal CB4 +

1 lb sulfamic

Pump in load 9:00-9:15

Start on PW-18

Surge 12:30-14:30

Sheet 1 of 

Signature and date (print name and title):

Plate D-11
EP 1110-1-27

27 Jan 00

Sheet 1 of 2

Plate D-12
EP 1110-1-27

27 Jan 00

Sheet 2 of 2

Plate D-12
EP 1110-1-27

27 Jan 00

Sheet 1 of 3

Plate D-13

Bldg 201
EP 1110-1-27

27 Jan 00

Sheet 2 of 3

Plate D-13
EP 1110-1-27

27 Jan 00

Sheet 3 of 3

Plate D-13