Groundwater Inventory, Monitoring, and Assessment Technical Guide
Contents
4.0
Monitoring Groundwater and Groundwater Systems .................................................................... 3
4.1
Groundwater Monitoring Design .............................................................................................. 3
4.1.1
Groundwater Monitoring Program Objectives ....................................................................... 3
4.1.2
Types of Groundwater Monitoring Programs ......................................................................... 4
4.1.3
Process for Designing a Groundwater Monitoring Network ................................................... 4
4.1.4
Considerations in Monitoring Network Design ....................................................................... 6
4.2
Groundwater Level Monitoring .............................................................................................. 16
4.2.1
Selection of Observation Wells, Springs, and Other Sites ..................................................... 16
4.2.2
Frequency of Water-Level Measurements............................................................................ 17
4.2.3
Quality Assurance for Water-Level Measurement................................................................ 18
4.2.4
Long-term Water-Level Monitoring Data .............................................................................. 19
4.3
Groundwater Quality Monitoring ........................................................................................... 20
4.3.1
Selection of Groundwater Quality Monitoring Sites and Parameters .................................. 21
4.3.2
Frequency of Groundwater Quality Sampling ....................................................................... 23
4.3.3
Techniques and Protocols for Groundwater Quality Sampling ............................................. 23
4.3.4
Sources of Sampling Error ..................................................................................................... 24
4.3.5
Quality Assurance and Quality Control Plans ........................................................................ 25
4.4
Evaluation and Reporting ....................................................................................................... 28
4.4.1
Water Quality Data Reporting ............................................................................................... 28
4.4.2
Water-Level Data Reporting .................................................................................................. 29
References ...................................................................................................................................... 32
Appendix 4-A – Quality Assurance and Quality Control Guidelines for Field Data Collection .............. 35
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4.0
Monitoring Groundwater and Groundwater Systems
Groundwater monitoring encompasses a wide variety of activities, including routine measurements of
water level in a network of observation or pumping wells, dye tracer studies, collection of groundwater
samples for characterization of the extent and movement of contaminants, and installation and
maintenance of stream gauges and meteorological stations. The nature and scope of monitoring
programs vary widely depending on the objectives of and resources available. This section describes how
to define monitoring objectives that are consistent with investigative objectives, as well as how to select
environmental indicators that are consistent with monitoring objectives. This section also presents
general guidelines for designing monitoring programs. Specific guidance is provided for collection of two
of the most common types of parameters in groundwater monitoring: groundwater levels and
groundwater quality.
The information in this section and associated documents is not intended to provide complete instructions
on how to perform the described activities. Although Forest Service personnel may be able to perform
some of them, most activities will require contractors with the appropriate skills and equipment. This
information is primarily intended to provide Forest Service personnel with a basic understanding of the
common activities and options associated with these types of projects, and a base of knowledge to
facilitate communication and project management.
4.1
Groundwater Monitoring Design
When designing and implementing monitoring programs, it is vital to consider the differences in the
spatial and temporal characteristics of ground and surface waters. Groundwater has a three-dimensional
distribution within a geologic framework, defined by aquifer and geologic characteristics and limited
accessibility (that is, groundwater must be sampled through a well, spring, or cave). Therefore, the design
and implementation of a groundwater monitoring program must be based on a conceptual model
grounded in a thorough understanding of the unique hydrogeologic characteristics of the groundwaterflow system under investigation and the locations of particular land uses and contaminant sources likely to
affect groundwater quality.
4.1.1
Groundwater Monitoring Program Objectives
The first step in any monitoring program is defining the objectives of the monitoring. The general
objectives for groundwater monitoring programs are:




Assess background groundwater quantity and quality conditions;
Comply with statutory and regulatory mandates;
Determine changes (or lack thereof) in groundwater conditions over time to define existing and
emerging trends, guide monitoring and management priorities, and to evaluate effectiveness of
land and water management practices and programs; and
Improve understanding of the natural and human-induced factors affecting groundwater (e.g.,
land use activities or facilities).
The monitoring program objectives should be specified in writing so that both the specialists and decision
makers have clear understanding of the purpose and goals of the monitoring.
Effective project management of inventory and monitoring programs can ensure appropriate quality
assurance and quality controls are incorporated into all program phases. Data quality benefits not only
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from development of an inventory or monitoring plan, but also from use of techniques and practices
described in Appendix 4-A.
4.1.2
Types of Groundwater Monitoring Programs
Several types of groundwater monitoring are conducted by Federal, State, local, and private organizations
to accomplish one or more of the objectives stated above. The general types include: background
monitoring (national or statewide monitoring), baseline monitoring (in advance of project or activity
initiation), and monitoring for compliance of permitted facilities.
Gathering background or baseline water quality data often involves sampling an area for the first time. A
wide variety of chemical, physical, and biological contaminants may affect groundwater resources (Fetter
1999). As a result, background groundwater monitoring programs are designed to establish
characteristics and to investigate long-term trends in resource conditions. The parameters measured in
baseline monitoring programs provide data on pre-activity groundwater conditions. Some common
baseline parameters in groundwater are water levels, temperature, and concentrations of elements,
species or chemical substances present which are derived naturally from geological, biological or
atmospheric sources or from human activities. For these monitoring efforts, parameters are identified on
the basis of a thorough understanding of the resource to be evaluated and the potential water quality
changes or sources of contamination involved.
Compliance monitoring is conducted in response to specific regulatory requirements or permit conditions
for facilities regulated under various programs. These can include the Resource Conservation and
Recovery Act (RCRA), the Safe Drinking Water Act, or monitoring in support of remedial activities such as
the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA). Compliance
monitoring is also conducted for mining and special use permits.
4.1.3
Process for Designing a Groundwater Monitoring Network
A general process for designing a groundwater monitoring network once objectives of the monitoring
program are clearly specified is outlined below (modified from Florida Department Environmental
Protection 2008, table 1). This approach was designed for monitoring water quality to identify
contaminants and should be adjusted to reflect the monitoring objectives in specific applications.
1) Describe the physical and hydrogeologic characteristics of the area, including:
a.
Direction and rate of groundwater flow, including impermeable barriers to flow.
b.
Hydraulic characteristics (hydraulic conductivity, storage properties) of aquifer(s).
c.
Areal extent and thickness of aquifer(s).
d.
Vertical hydraulic conductivity, thickness, and extent of any confining beds.
e.
Topography, soil, and vegetation information, and surface water drainage systems
surrounding the site.
f.
Areas of potential recharge (including septic return, wastewater recharge basins, and effluent
streams).
g.
Areas of potential discharge (including springs, wetlands, and pumping wells).
h.
Precipitation and evaporation rates.
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i.
River, stream, and spring flow rates.
j.
Ambient groundwater quality.
2) Depending on project objectives, identify the characteristics of the area relevant to groundwater
quality or contamination.
a.
Known water quality for all aquifers, other groundwater-bearing media, and associated
surface water.
b.
The locations of known or suspected releases of contamination that could impact
groundwater and the associated types of contamination.
c.
The locations of known or suspected activities with a potential to release contamination to
groundwater and the associated types of contamination.
d.
The locations and extents of known or suspected groundwater contaminant plumes and the
associated types of contamination.
e.
The locations and extents of other known or suspected groundwater quality concerns and the
associated types of constituents.
f.
The locations and nature of all potential groundwater receptors (including, water supply wells,
springs, and groundwater-dependent ecosystems).
g.
Potential flow paths and their associated characteristics that could affect water quality or the
migration of contaminants (including, hydraulic conductivity, natural attenuation factors, and
the presence of chemicals or constituents that could reduce or increase contaminant
migration or impacts).
3) Establish project data quality objectives and associated levels of data quality. Depending on
project objectives (e.g., meeting regulatory requirements), there may be required procedures for
quality assurance and quality control. Otherwise consult applicable guidance materials (for
example, the U.S. Environmental Protection Agency [EPA] website on quality management at
http://www.epa.gov/quality/; U.S. EPA 2012).
4) Establish criteria for selecting existing monitoring wells and other monitoring sites (Lapham et al.
1997, pp. 6-11 discuss selection of existing wells, selection criteria for the wells, and limitations
and advantages of using existing wells for groundwater monitoring).
a. Obtain design specifications and construction data for the existing monitoring wells, confirm
they can be used to meet project objectives, and establish elevations of measuring points at
the selected wells and other monitoring sites.
b. Identify the existing monitoring points meeting the criteria to be used.
5) Identify the locations of the proposed monitoring sites necessary to fill in the gaps in the existing
monitoring sites.
a. Determine the construction and development requirements of any new wells (see Forest
Service Groundwater Technical Note on Well Construction and Development) or other
monitoring sites;
6) Indicate those designated as background or potentially contaminated sites.
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7) Establish and document natural background (where available) or background quality of the
groundwater in the vicinity of the monitoring network.
8) Develop measurement and sampling frequency for monitoring sites.
9) Establish a schedule periodically to review the monitoring data (to check for anomalies, data
collection or equipment problems and network effectiveness), and establish data analysis
protocols for review of monitoring data.
10) Develop a decommissioning plan for sites1 in the monitoring network for such a time when the
network is no longer required (note that some states may have limits on how long wells may
remain in place if they are no longer being used as well as requirements for their abandonment;
check for any State requirements or guidance first).
11) Develop a field safety plan for conducting the monitoring activities.
4.1.4
Considerations in Monitoring Network Design
Observation networks are designed for a specific purpose. A network may be used to monitor long-term
effects of climatic changes on groundwater systems, to monitor the effects of a new well field adjacent to
a unit on groundwater levels within the administrative boundaries, or to monitor contaminant movement
from a landfill or other pollution source. Each of these networks has different design considerations.
This section includes a general discussion of factors that should be considered in the design of monitoring
networks, including well placement, the use of new and existing wells, and cost as a limitation on
monitoring. Forest Service Groundwater Technical Notes address related field procedures, including:




Groundwater Level Measurement,
Well Construction and Development,
Groundwater Monitoring Well Installation for Shallow Water Tables and Wetlands
Groundwater Sampling
Proper design of a monitoring network is critical to meeting monitoring objectives successfully.
Groundwater monitoring undertaken by the Forest Service typically is oriented towards addressing sitespecific or project-specific issues such as mine operations, CERCLA activities, snow making, water rights,
drinking-water system operation, or particular Forest Service research projects, including prescribed fire
and thinning (ACWI 2009, p. 25). Other Federal agencies, such as the U.S. Department of Interior, U.S.
Geological Survey (USGS) and the National Park Service, EPA, and individual State agencies also maintain
groundwater monitoring networks, but each network is designed to meet agencies’ specific objectives.
Although this section focuses on the use of monitoring wells, both springs and surface water bodies (if
present) should also be monitored to provide a more complete picture of the hydrologic system.
A well-designed groundwater monitoring network will fulfill the monitoring objectives and be cost
effective. The type, depth, construction details, and locations of wells and the types and locations of other
1
To avoid having to deal with orphaned wells, if a third party will be responsible for installing and maintaining monitoring wells on NFS lands be
sure they provide a decommissioning plan for the wells or that the responsibility for maintenance and decommissioning of the wells is expressly
passed on to someone else.
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monitoring points that comprise the network (see Forest Service Groundwater Technical Note on
Monitoring Well Construction and Development) are highly dependent on the objectives of the network.
For example, is the network intended to monitor groundwater levels only or to also monitor water
quality? Is the network intended to monitor natural or undisturbed groundwater conditions or to monitor
the effects of development (e.g., pumping, mining) or contaminant movement? If the network is intended
to monitor the effects of development or land management activities, baseline hydrologic conditions
should be established by the network prior to development. If the network is intended to monitor
movement of existing or potential contaminants, information on the type(s) of contaminants and the
frequency of monitoring will be needed. In addition, it will be necessary to identify whether the
contaminants of interest might exist at background levels in the groundwater system. A network intended
to monitor salt-water intrusion into an aquifer will be much simpler than one intended to monitor low
levels of hazardous chemicals.
Equally critical to the success of the monitoring network is an understanding of the hydrogeologic
conditions of the area to be monitored. This understanding is fostered through the development of a
conceptual model of the area. Knowledge of groundwater flow paths allow monitoring wells to be located
in the correct areas to detect contaminants, as well as to monitor background conditions (i.e.,
uncontaminated conditions or pre-existing occurrences). Design of a network to monitor a relatively
uniform, alluvial aquifer can be very different from a network to monitor groundwater in a fractured-rock
or karst aquifer. The American Society for Testing Materials (ASTM 1996) and U.S. EPA (Quinlan 1989)
developed guidelines for monitoring and sampling groundwater in karst and fractured-rock aquifers.
Selection of the optimum number of wells to include in the monitoring network is often a hit-and-miss
process. It may be impractical and expensive to include all existing wells in the network, although this is
commonly done. Wells may exist in areas or produce from depths or ranges of depths that will not
monitor or detect movement of the contaminant of interest so these wells may not need to be monitored.
Use of statistical methods to select wells to monitor, or to locate new wells, may improve the cost
effectiveness of the network as illustrated in figure 4-1. This pair of maps illustrate that a small number of
strategically-placed wells can provide a much greater “return on investment” than a large number of
wells. Visual Sample Plan (VSP) developed by the Pacific Northwest National Laboratory
(http://vsp.pnnl.gov/) and Spatial Analysis and Decision Assistance (SADA) developed by the University of
Tennessee-Knoxville (http://www.sadaproject.net/) are two well developed and widely accepted software
tools that support the development of a defensible sampling plan based on statistical sampling theory and
the statistical analysis of sample results. They can be downloaded and used for free.
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Figure 4-1—(A) Water-level elevation in the Equus Beds aquifer, in central Kansas, based on a network
of 244 observation wells. (B) Water-level elevation in the Equus Beds aquifer, based on data from a
network of 47 wells selected by using 16-square-mile hexagons. The two contour maps are very similar,
differing by less than 5 percent. (Taylor and Alley 2001, figs. C-1, C-2).
Analysis of groundwater models may also help to identify gaps in the monitoring network and indicate
areas where additional monitoring wells need to be located. If wells need to be drilled to fill in gaps in the
monitoring network, they should be located and constructed in such a way as to ensure that objectives of
the monitoring network are met. In addition to wells, springs and surface water bodies within the area
should also be monitored, even if they are on adjoining private land.
For identifying and delineating contaminant plumes it has become common practice to use an approach
that permits rapid collection and field-based analysis of samples so that new sample locations can be
identified and sampled during the same field effort. Ideally, the extent of contamination will be identified
in just one round of field work. The Triad approach was originally developed by the U.S. EPA to specifically
facilitate these types of “dynamic field investigations.” It is now supported by multiple Federal and State
agencies through the Triad Resource Center (2012).
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The most common approach is to use direct-push technology, such as a Geoprobe®, to establish holes and
install temporary wells for collection of soil and grab groundwater samples. For small investigations,
sample location selection is guided by visual or olfactory indications of contamination in soil samples as
well as field measurements or screening by using easily operated equipment. For large investigations,
more advanced field-based analytical techniques, including mobile field laboratories, can cost effectively
allow selection of new sample points and delineation of contamination in the field. Permanent monitoring
wells are then installed and sampled for laboratory analyses to confirm the results of the initial
investigation. If the contaminants of concern are sufficiently volatile, it may be more cost effective to
perform a soil gas survey first to tentatively identify the extent of contamination and then place and
sample monitoring wells to confirm it.
Surface geophysical methods might allow preliminary identification or delineation of important geological
or hydrogeological characteristics or contaminant extent (see Forest Service Groundwater Technical Note
on Geophysical Methods). This may help minimize the number of monitoring wells required while
optimizing their placement.
Monitoring Program Design
Monitoring program design addresses the geographic area covered by the program, the number and type
of wells and other monitoring sites needed to characterize conditions accurately, the frequency of
measurement or sampling, and the parameters to be monitored, including the specific water quality
constituents to be analyzed (if any). In determining the program design, a critical issue affecting program
costs is the decision whether to use existing wells or to install new monitoring wells. Existing wells may be
found in the area to be monitored in the form of community water supply or residential drinking water
wells, irrigation wells, or wells used for compliance monitoring or other ambient monitoring activities.
Existing wells may be adequate to support the monitoring program if they are completed within the
aquifer of concern, screened at an appropriate sampling depth, constructed properly, and in sufficiently
acceptable condition so as not to interfere with the sampled analytes.
The number of water quality analyses within a sampling cycle (e.g., annually) can be determined based on
the number of analytes, the number of wells, and the sampling frequency (e.g., quarterly versus annually).
Depending on the purpose of the monitoring, add additional analyses of quality control samples to the
primary set of analyses. Ideally these requirements will be known or easily determinable up front for
common types of monitoring. If not determined initially, the number of quality control samples can be
assumed to be about 10 to 20 percent of the primary samples for preliminary planning purposes. Finally,
the monitoring program design should also include provisions for establishing data processing and
management, quality assurance, reporting, and interpretation methods. These program design guidelines
establish the basis for conducting and executing all other components of a groundwater monitoring
program.
Use of Existing Wells
Identification of existing wells that are suitable for monitoring may be divided into three steps: (1) identify
all the wells in existing databases that are screened only in the hydrogeologic unit targeted for monitoring;
(2) apply a screening process to the wells identified in step 1 to determine the subset of wells that meet
the explicitly defined suitability criteria for monitoring; and (3) evaluate the spatial distribution of wells
that are suitable for monitoring, not only in map view but also relative to the depths of the screened
intervals of these wells within the hydrogeologic unit(s) of interest. This evaluation is accomplished most
efficiently by plots of wells on a map, showing depth of screened interval below the water table or depth
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of screened interval relative to total thickness of each hydrogeologic unit. An important prerequisite for
screening existing water quality data is the existence (preferably in an electronic database), of basic
information on well location, well-construction details, and at least one water level when the well was not
being pumped. Large numbers of otherwise suitable wells may have to be eliminated as candidates for
monitoring because essential information about the wells is not available.
Criteria for wells that are suitable for monitoring may vary for different projects. Therefore, a critical
initial action in defining suitable wells is to list explicitly (and document subsequently) a set of criteria that
must be present, and information about the well that must be available to meet the minimum acceptable
criteria for monitoring. These same criteria are a starting point in developing specifications for newly
constructed project wells.
A monitoring well should yield water from the particular zone (hydrostratigraphic unit) that is targeted for
monitoring. Wells that are completed across more than one hydrostratigraphic unit provide information
on subsurface conditions that mixes water quality and water-level data. Often, it can be difficult or
impossible to attribute the data that belong to each unit. When resources are tight and the need for
additional monitoring points is critical, groundwater specialists often will utilize wells that are completed
across hydrostratigraphic units. When this happens, provisions have to be made to interpret the
information from those wells.
A monitoring well should be adequately constructed and completed at a depth that is relevant to the
program objectives. Well construction information should be available, obtained, or measured for any
well that is to be sampled. Information such as screened interval, total depth, size and type of well casing,
filter pack, and surface seal design, should meet the needs of the monitoring program. Key considerations
include: (a) Length of intake interval—project objectives may not be served by very long well screens or
long open-hole intervals in bedrock wells because these create uncertainties in the water source; (b) the
type of casing material—results of monitoring for metals may be compromised by metal casing, and some
volatile organic compounds (VOCs) by PVC casing, particularly if casing joints are glued; and (c) methods of
drilling and developing the well—could introduce contaminants into the strata or change the chemical
environment in the vicinity of the wellbore (Brobst 1984).
Finally, the current condition of an existing well must meet the needs of the monitoring program. A well
may have deteriorated or may not have been properly maintained and, therefore, may no longer be
suitable for monitoring purposes. For example, the screen on a water supply well may be obstructed by
iron oxide or bacteria, or have a cracked casing that allows shallower water to enter the well. A
monitoring well may have a damaged riser pipe, surface cover, or seal, or have suffered frost heave that
has pulled its screen above the top of the filter pack. If its surface cover/riser pipe is missing or otherwise
unsecured the well may have been contaminated by surface runoff or deliberate placement of materials
down it. If use of a particular well is highly desired but there are concerns about its conditions, it may be
worth having it inspected by a qualified well driller or other contractor. This may require the use of a
borehole televiewer to inspect the well’s interior condition. At a minimum, all candidate wells should be
field assessed for obvious problems before final selection.
Use of Surface Water Monitoring Sites
Groundwater and surface water monitoring should be integrated where applicable. Because groundwater
and surface are often interconnected across the landscape, surface water features (ponds, lakes, springs,
wetlands, streams) frequently reflect the elevation of a shallow water table as well as points of
groundwater recharge or discharge. Including these points in a water monitoring network makes sense
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because they are locations where data can be acquired without the expense of installing a monitoring well
and they may support a groundwater-dependent ecosystem. Surface water monitoring locations are also
critical when the objective is to define groundwater/surface water interactions, for example, to determine
the effect of groundwater use on stream flow and fisheries habitat. Similarly precipitation may need to be
monitored to help explain changes in groundwater levels or surface water systems.
Installation of New Monitoring Wells
New project wells may be needed either for all samples in the study, to “fill in the gaps” where wells do
not exist, or where suitable wells or other monitoring points are not available. The obvious advantages of
constructing new project wells include: (a) selection of the well location and access to the well for
monitoring; (b) designation of the screened interval of the well within the hydrogeologic unit; (c) control
over specific construction features of the well (well design); and (d) assurance of long-term availability of
the well for monitoring. The principal disadvantages of constructing new project wells are the potentially
large additional costs for the project and the increased time and costs associated with obtaining any
needed permits, and the permitting and legal easements to drill wells in desired locations. Additional time
is also required for completing all required environmental documents. It is also important to remember
that each new well or boring represents a potential conduit for contaminant migration or groundwater
flow and must be considered a potential liability to investigative activities.
If available, follow any guidance/requirements for wells related to the program under which you are
conducting monitoring (i.e., State environmental regulations). Additional guidance on constructing and
developing monitoring wells can be found in the Forest Service Groundwater Technical Notes on Well
Construction and Development.
One type of monitoring well that often justifies special design and construction as a new well is a
monitoring well that will be used for long-term monitoring, that is, a “trend analysis” well or wells as
reference for comparing data and trends from nearby developed lands. Because of the large costs to
collect and analyze the samples over a period of many years, reliability of the data is imperative, and a
well specifically drilled and constructed for this purpose would likely be cost effective.
Another type of monitoring well that often justifies construction as a new well is a shallow, driven or
hand-augered well. This type of well is only suitable in particular hydrogeologic settings (shallow water
table in generally soft sediments), is relatively inexpensive, and can be constructed in many areas that may
not be amenable to access by a drill rig (see Forest Service Groundwater Technical Notes on Groundwater
Monitoring Well Installation for Shallow Water Tables and Wetlands).
Effective monitoring well design and construction require considerable care and at least some
understanding of the hydrogeology and subsurface geochemistry of the site. Preliminary borings, well
drilling experience, and the details of the operational history of a site can be very helpful. Monitoring well
design criteria include size and material of the well, depth, screen size, filter pack specifications, and yield
potential. These considerations differ substantially from those applied to water supply wells. The
simplest, small-diameter well completions that will permit development, accommodate the monitoring
gear, and minimize the need to purge large volumes of potentially contaminated water are preferred for
effective routine monitoring activities. Helpful references include Barcelona et al. (1983), Driscoll (1986),
Lapham et al. (1997), and Wehrmann (1983).
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Well Placement
The placement and number of wells in a network, as well as the placement and number of rain gauges or
stream gauging stations, depends upon the purpose of the network and the hydrogeologic complexity of
the study area. Ideally, the wells chosen for an observation network provide data representative of the
topography, geology, soils, climate, and land-use environment present within the area of interest. The
more varied these environments are within that area, the more wells will be needed. Geophysical
techniques (see Forest Service Technical Note on Geophysical Methods) can be very helpful in determining
the optimum placement of monitoring wells under appropriate conditions and when sufficient
hydrogeologic information is available (Evans and Schweitzer 1984).
The placement and number of wells also depend upon the degree of spatial and temporal detail needed to
meet the goals of the program. Placement and number may also be constrained by surface conditions,
including concerns about site access (remote areas or non-National Forest System property) and
protecting the well from damage or vandalism. An understanding of the variability or distribution of
hydraulic conductivity, in both the vertical and horizontal dimension, allows one to isolate the major zones
of water transmission and, therefore, to select the proper depths of wells and the position and length of
well screens. Accurately identifying vertical aquifer boundaries and placing screens is critical not just
because cross-connecting two aquifers will negatively impact the monitoring results, but also because it
may allow contamination to travel from one aquifer to another or otherwise negatively affect an aquifer.
With this knowledge, it also may be possible to estimate the nature and location of pollutant sources for
sites where contamination is an issue (Gorelick et al. 1983). Well placement should be viewed as an
evolutionary activity or an “adaptive approach” that may expand or contract as the needs of the program
dictate.
For contaminant monitoring, wells should be placed within and near the area of the suspected
contamination pathway including the source area if possible, as well as upgradient of the site. Initial
investigations need to be carried out to determine the flow system before effective monitoring wells can
be installed. If hydrogeologic conditions are such that there are several aquifers present, then observation
wells that monitor each individual aquifer will be required. This can be accomplished by using multiple
wells, each completed in an individual aquifer and isolated from the others at a site, or by the use of
multiple screened intervals isolated from other aquifers by using packers or some other isolating medium
such as bentonite or cement. Wells completed at multiple depths may also be needed in situations where
there are vertical head gradients within a single aquifer (e.g., near a lake or stream that receives
groundwater discharge), or where contaminant migration may be along preferential flow paths (fractures
or sand lenses). Where multiple-completion wells are required, care should be taken physically to isolate
each zone of interest. Detailed discussions of well design, well completion, and well development are
described in Lapham et al. (1997).
The placement of nested piezometers in closely spaced, separate boreholes of different depths is
generally the preferred method for determining vertical head differences and the potential for vertical
movement of contaminants, while monitoring wells with appropriately located screens are used to
determine the lateral movement of contaminants in the saturated zone. One should also consider
whether vadose zone monitoring is required. Nested lysimeters can be used to detect contaminants in
the vadose zone.
For contaminant monitoring, determination of the length and position of well screens also must be based
on the nature of the contaminant. For example, if the contaminants are miscible with the liquid phase, it
may be possible to use only one well per monitoring point. It also may be possible to use only one well if
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the transmissive zone is very thin. If the contaminants are immiscible with the liquid phase (i.e., sinkers or
floaters) the well screen must be located accordingly. The length of well screen selected is relative to the
vertical scale of investigation, and to the thickness of the hydrogeologic unit of interest. The longer the
screened (or open) interval relative to aquifer thickness, the less likely will be the ability to distinguish
differences in water quality at specific depth intervals. Mixing of waters within the screened interval can
lead to constituent concentrations that do not necessarily represent the maximum or minimum
concentrations of those constituents within the aquifer. For this reason, relatively short screens are used
when the objective is to investigate water quality at discrete intervals and to define chemical stratification
within the aquifer. If determining the vertical distribution of water quality in an aquifer is the objective,
installing wells at different depths, each with a relatively short screen length, is often the most effective
design.
Screen lengths for monitoring wells typically range from 2 to 20 feet (-0.6 to 6 meters). As a general rule,
screen lengths of 20 feet or less generally are appropriate for most assessment studies (10 feet are
standard for monitoring at the water table and 5 feet are standard for below it). Screen lengths of 5 feet
(-1.5 meters) or less generally are better suited for studies to determine fate, transport, and geochemistry
of groundwater constituents. A screen length of 5 feet might be too long if information suggests that
marked vertical differences in the distribution of hydraulic head or water quality occur on the order of a
few feet or less.
The length of the open interval also depends on the scale of the investigation. For example, a 20-foot-long
screen is too long for an investigation of a 5-feet-thick contaminant plume, whereas it might be
considered too short in an investigation of the water quality in an aquifer that is several hundreds of feet
(tens to hundreds of meters) thick. A 100-foot-long (about 30.5 meters) open interval might be
considered short in an investigation of the water quality of an aquifer 1,000 feet (305 meters) thick.
Additional factors to consider when deciding on screen length are:



A short screen generally provides measurements of hydraulic head and groundwater quality that
more closely represent point measurements than measurements provided by a long screen.
However, a short screen interval in a thick hydrogeologic unit may entirely miss sampling a zone of
contamination. This is a particular risk in assessing fractured bedrock where only a small subset of
the fractures may control groundwater flow.
Samples taken from wells with long screened intervals could exhibit smaller concentrations or a
higher frequency of samples with nondetectable concentrations (leading to a "false negative"
assessment) in comparison to samples taken from wells with short screened intervals.
A long well screen also can induce mixing of waters of different chemistry in comparison to a short
well screen because of vertical flow along the screened interval and because of differences in head
along the screened interval (well-bore flow). Well-bore flow can occur even in homogeneous
aquifers with very small vertical head differences. Well-bore flow might also contribute to aquifer
contamination by providing a pathway for contaminant movement from contaminated to
uncontaminated zones along the screened interval(s).
Groundwater-Dependent Ecosystem Monitoring
Depending on the purpose of the groundwater monitoring, it may be appropriate to include monitoring of
groundwater-dependent ecosystems (GDE). For example, it may be necessary to monitor the potentially
affected GDEs for a proposal that involves the withdrawal of groundwater, such as a mine or water supply
well. The existing GDE Field Guides provide a foundation for developing a GDE monitoring program. For
additional, information on GDE inventory and monitoring, see Section 3 of this technical guide. Another
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useful resource for GDE monitoring is the Forest Service Groundwater Technical Note on Groundwater
Well Installation for Shallow water Tables and Wetlands that provides guidance on hand installation of
shallow wells. Fonseca (2008) discussed monitoring groundwater-dependent ecosystems in southeastern
Arizona, and presented a generalized monitoring plan for these systems.
Monitoring Network Installation
Installing a well or piezometer is the best way to understand and monitor subsurface hydrogeologic
conditions. There are a number of methods available to install a well, and determining the best method
depends on both the use of the well and the hydrogeologic environment. The available well installation
methods generally fall into two categories, driven or drilled. Driven wells are most useful in areas where
the groundwater system of interest is located in unconsolidated geologic materials relatively near the
ground surface, and can be as simple as pounding a minipiezometer into soft sand with a hammer. Drilled
wells can be installed in most geologic settings. In areas of unconsolidated material with shallow
groundwater, hand installation can be used.
In areas with consolidated bedrock, drilling can require the use of a large drilling rig with ancillary
equipment and a large field crew. With drilled wells in particular, the drilling is only the beginning. Once
the borehole is drilled, the well must be completed and equipped for its intended use. Well completion
includes installation of casing or screens, surrounding the casing with the appropriate “packing” material
that will either restrict or promote water flow to the well, “development” of the well to maximize water
flow to the well and to ensure a good connection between the well and the aquifer, and a well
performance test or specific capacity test. Monitoring well installation also includes surveying their
completed locations and top of casing elevations so that the wells can be accurately located on a map and
measured water levels can be converted to elevations.
The selection of a particular drilling technique for observation-well construction depends on the geology
of the site, the expected depths of the well, the requirements for subsurface lithologic samples, and the
suitability of drilling equipment for the contaminants of interest. Available drilling methods include auger,
rotary using air or water-based fluids, cable-tool, jet-wash and jet-percussion, coring, direct-push, and
vibration drilling methods. The advantages and disadvantages of each method are described in detail by
Lapham et al. (1997, pp. 47–63). Regardless of the technique used, every effort should be made to
minimize subsurface disturbance. For environmental applications, the drilling rig and tools should be
steam cleaned at the start and between each hole to minimize the potential for cross-contamination
between formations or successive borings. Samplers, such as split spoons or Shelby tubes for soil
sampling, should be cleaned between each sample.
As a rule, soil samples, rock cuttings, or rock cores should always be collected and logged by a qualified
person during drilling to obtain a record of geological conditions encountered at the well site and to
confirm the placement of the screen. Samples may also be needed to assess the potential presence of
contamination above groundwater. Wells should only be blind drilled if they are being placed next to a
boring of the same or greater depth that has been previously logged. Wells should never be blind drilled
solely to save money and time. If possible, storing and saving unused samples until the project is
completed may help avoid data gaps or the additional costs of resampling if there are later questions
about what was found. If drilling to evaluate contamination, be sure all drill cuttings and unsaved samples
are stored and disposed of in compliance with applicable laws and regulations.
The Forest Service Groundwater Technical Note on Monitoring Well Construction and Development
provides guidelines for construction (drilling, setting casing, and packing) and development of monitoring
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wells. The Forest Service Groundwater Technical Note on Groundwater Well Installation for Shallow water
Tables and Wetlands provides guidance on hand installation of shallow wells.
Monitoring Network Cost Considerations
Monitoring program costs can be classified into two categories: (1) development costs and (2) operating
costs. Development costs encompass activities involved in designing and initiating a monitoring program
and a monitoring network. Development costs include:



Monitoring program design;
Monitoring network installation; and
Aquifer analysis tests.
Development costs occur during the process of defining, establishing, and installing a monitoring program.
Additional development costs may be incurred as information is collected and analyzed from the initial
network and additional data gaps are recognized and the program is adapted to the actual data being
collected.
Monitoring network installation costs can encompass a significant portion of a monitoring program's initial
budget, particularly if existing wells are not adequate. Key factors influencing the number of wells in a
monitoring program design include the geographic size of the monitored region and the hydrogeologic
complexity of the groundwater system. For example, heterogeneous aquifer systems or systems with
rapid groundwater velocities may require a greater number of wells than more homogeneous, slowmoving groundwater systems to characterize local contamination issues.
Operating costs extend over the period of operation of the monitoring network. These operating costs
include all activities needed to collect, process (Quality Assurance/Quality Control), analyze, and report
data. These costs are characterized by the following seven components.:
Monitoring network maintenance - Maintenance costs consist of well integrity inspections and repairs
to correct well anomalies, repair of damaged staff gauges, etc. Top of casing elevations should be
periodically resurveyed as part of maintenance following repairs or if movement of the casing is
suspected, such as due to frost heave. Shallow monitoring wells, in wetlands for example, must be
resurveyed every year to account for vertical movement. Well repairs can range from regrouting to
closure of the monitoring well and the installation of a replacement.
Groundwater measurement and sampling - The measurement and sampling component incorporates
the costs of labor, materials, and expenses of site visits for measuring water levels, gathering other
data, and collecting samples and transporting them to a laboratory for analysis. The requirements
associated with shipping samples, including where and when they can be shipped, how soon they
must be received by the laboratory, and when the laboratory can receive them, can have a significant
impact on the field schedule and expenses.
Groundwater sample analysis - Laboratory analysis costs may vary significantly because different
analytical methods are used for different groups of analytes. A common oversight in estimating these
costs is to omit those associated with analyzing associated quality control samples.
Data management and quality assurance - Data management entails ensuring standardized and
accepted methods of data collection are used and that data are processed, documented, and stored in
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digital databases that have adequate backup and archival procedures. For projects where data quality
assurance requires verification (i.e., for some types of regulatory compliance and for anything subject
to litigation) allowances should be made for some type of independent data quality review and
verification.
Data interpretation - Comprehensive data interpretation may not strictly be considered a part of
monitoring costs, especially if the monitoring effort is conducted as part of a larger hydrogeologic
investigation. Monitoring programs should budget for data interpretation to evaluate the
performance of the monitoring program and allow for ongoing adjustments based on the results.
Reporting of monitoring results - Several methods are used to report monitoring results, including:
publishing a groundwater quality status report, conducting a groundwater quality seminar, conducting
a workshop among the stakeholders, or making monitoring results available for online access. The
goal of program communication is to inform management and the public about the status of
groundwater monitoring efforts.
Monitoring program evaluation and redesign - Monitoring program evaluation compares the
program’s goals with results achieved. The effectiveness and deficiencies uncovered by the evaluation
form the basis for program redesign, if present goals are not currently being met.
Operating costs are incurred to support ongoing implementation of the monitoring program. These costs
may vary from year to year, as the number of wells measured or sampled, the number of analytes
assessed, or the level of resources devoted to data management and reporting may change. One
important aspect of assessing operating costs, and by extension monitoring program viability, if
monitoring is to span multiple years, is to consider the time frame of monitoring against the likely
availability of funding and suitable personnel to conduct the monitoring. To ensure monitoring will be
sustained as long as needed, it may be necessary to get the monitoring integrated into forest planning
documents.
4.2
Groundwater Level Monitoring
Water-level measurements from observation wells are the principal source of information about the
hydrologic stresses acting on aquifers and how these stresses affect groundwater recharge, storage, and
discharge. Generally, water-level measurements taken in boreholes, piezometers, or monitoring wells are
used to construct water table or potentiometric surface maps and to determine flow direction and other
aquifer characteristics. A Forest Service Groundwater Technical Note on Groundwater Level
Measurements provides guidelines for determining the depth to water in an open borehole, cased
borehole, monitoring well or piezometer, domestic well, and in soil pits.
4.2.1
Selection of Observation Wells, Springs, and Other Sites
All groundwater-level monitoring programs depend on the operation of a network of monitoring sites.
These generally include observation wells—wells selected expressly for the collection of water-level data
in one or more specified aquifers–and staff gauges for springs and those lakes and streams that are well
connected with the aquifer(s) of interest. Decisions made about the number and locations of monitoring
sites are crucial to any water-level data collection program. Decisions about the areal distribution of all
sites and the depth of completion of observation wells also should consider the physical boundaries and
geologic complexity of aquifers under study. Water-level monitoring programs for complex, multilayer
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aquifer systems may require measurements in wells completed at multiple depths in different geologic
units. Large aquifer systems may require a network of observation wells that extends beyond the unit
boundaries. If one of the purposes of a network is to monitor ambient groundwater conditions, or the
effects of natural, climatic-induced hydrologic stresses, the observation network will require wells that are
unaffected by pumping, irrigation, or other water management and land uses that substantially affect
groundwater recharge. These and many other technical considerations pertinent to the design of a waterlevel observation network are discussed in detail in technical papers by Heath (1976), Peters (1972), and
Winter (1972).
Commonly overlooked is the need to collect other types of hydrologic information as part of a water-level
monitoring program. Meteorological data, such as precipitation and barometric pressure, aid in the
interpretation of water-level changes in observation wells. Monitoring of other parameters, such as
precipitation (and streamflow), may be needed to supplement the water-level data particularly in remote
areas or in small watersheds, if meteorological data are not available. In addition, water-use data, such as
pumping rates and volumes of pumped water, can greatly enhance the interpretation of trends observed
in water levels and explain changes in the storage and availability of groundwater that result from water
withdrawals over time.
4.2.2
Frequency of Water-Level Measurements
The frequency of water-level measurements is among the most important components of a groundwaterlevel monitoring program. Although often influenced by financial considerations, the frequency of
measurements should be determined to the extent possible by the anticipated variability of water-level
fluctuations in the observation wells and the data resolution or amount of detail needed to characterize
the hydrologic behavior of the aquifer. Figure 4–2 shows the relationship between frequency of waterlevel measurements in observation wells and various environmental factors.
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Figure 4-2—Common environmental factors that influence the choice of frequency of water-level
measurements in observation wells. (Taylor and Alley 2001, fig. B-1)
Typically, collection of water-level data over one or more decades is required to compile a hydrologic
record that encompasses the potential range of water-level fluctuations in an observation well and to
track trends with time. Systematic, long-term collection of water-level data offers the greatest likelihood
that water-level fluctuations caused by variations in climatic conditions and water-level trends caused by
changes in land use or water management practices will be “sampled.” The availability of long-term
water-level records greatly enhances one’s ability to forecast future water levels or to detect future
changes in water levels related to factors such as climate change or groundwater usage.
For groundwater-dependent ecosystems, project objectives might require very frequent measurements
(hourly) to capture the variability inherent in these systems. For example, water levels in wetlands and
flows in springs vary diurnally due to evapotranspiration from plants during the day.
4.2.3
Quality Assurance for Water-Level Measurement
Good quality-assurance practices help to maintain the accuracy and precision of water-level
measurements ensuring that the monitoring sites reflect conditions in the aquifer being monitored, and
provide reliable data for many intended uses. Consider carefully and consistently employ field and office
practices that will provide the needed levels of quality assurance for water-level data.
Some important field practices that ensure the quality of groundwater-level data include: establishment of
permanent reference points for water-level measurements (datums) for observation wells and staff
gauges, periodic inspection of well structures, and periodic hydraulic testing of wells to ensure their
communication with the aquifer. The locations and the altitudes of all observation wells and staff gauges
should be accurately surveyed to establish horizontal and vertical datums for long-term data collection.
Inaccurate datums are a major source of error for water-level measurements. Depending on the length of
the monitoring program, well and staff-gauge elevations may need to be periodically resurveyed,
especially if they may be subject to the effects of frost heave, subsidence, or other alterations of the
enclosing geological materials. Recent advances in the portability and operation of traditional surveying
equipment and in Global Positioning System (GPS) technology, have simplified the process of obtaining a
fast, accurate survey of well and gauge location coordinates and datums. In addition, to aid in locating
wells that may become lost or are simply hard to find, it is good practice to establish horizontal
coordinates from a nearby permanent benchmark and to take photographs of the well with identifiable
landmarks.
Existing wells selected and used for long-term water-level monitoring should be carefully examined to
ensure that no construction defects or deteriorated conditions are present that might affect the accuracy
of water-level measurements. This may entail the use of a downhole video camera to inspect the well
screen and casing construction. Over time, silting, corrosion, or bacterial growth may adversely affect the
way the well responds to changes in the aquifer. Any well selected for inclusion in an observation network
should be hydraulically tested to ensure it is in good communication with the aquifer of interest (see
procedure for slug testing described in Forest Service Groundwater Technical Note Instantaneous Change
in Head (Slug) Testing).
To help maintain quality assurance, establish a permanent file that contains a description of well and
gauge location coordinates, the datum used for water-level measurements, well construction and
development details, and the results of hydraulic tests. Water-level measurements should be compared
on a regular basis, or when one appears to be unusual, with previous measurements made under similar
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hydrologic conditions to identify potential anomalies in water-level fluctuations that may indicate a
malfunction of measuring equipment, problems with survey elevation, or a defect in the observation well.
Unusual measurements should either be documented as valid or invalid for an identifiable reason, or, if
that is not feasible, questionable with an assessment of their reliability.
4.2.4
Long-term Water-Level Monitoring Data
Water-level data are collected over various lengths of time, depending on their intended use(s). Shortterm water-level data are collected over periods of days, weeks, or months during many types of
groundwater investigations (see table 4–1). For example, tests done to determine the hydraulic
properties of wells or aquifers typically involve the collection of short-term data. Water-level
measurements needed to map the elevation of the water table or potentiometric surface of an aquifer are
generally collected within the shortest possible period of time so that hydraulic heads in the aquifer are
measured under the same hydrologic conditions. Usually, water-level data intended for this use are
collected over a period of hours, days, or weeks, depending on the logistics of making measurements at
different observation-well locations. Keep in mind the longer taken to complete a round of
measurements, the less reliable the final results. When doing multiple things at the wells (i.e., water-level
measurements, purging, sampling), a good practice is to collect water-level measurements at all wells first,
if feasible. Water-level data should always be collected at a well before any other activity that could affect
its water level. It may be necessary to restart a water-level collection round if it is interrupted by an event
that may affect groundwater levels (i.e., rain).
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Table 4-1—Typical length of water-level data collection as a function of the intended use of the data
(Taylor and Alley 2001).
Intended use of water-level data
Typical length of data-collection effort or hydrologic record required
Days/weeks
Months
Years
Decades
Determining the hydraulic properties of
aquifers (aquifer tests)
Mapping the elevation of the water
table or potentiometric surface
Monitoring short-term changes in
groundwater recharge and storage
Monitoring long-term changes in
groundwater recharge and storage
Monitoring the effects of climatic
variability
Monitoring regional effects of
groundwater development
Statistical analysis of water-level trends
Monitoring changes in groundwater flow
directions
Monitoring groundwater and surfacewater interaction
Numerical (computer) modeling of
groundwater flow or contaminant
transport
Note: Blue check marks = Most applicable for intended use. Yellow check marks = Sometimes applicable
for intended use.
Many of the applications of water-level data involve the use of analytical and numerical (computer)
groundwater models. Water-level measurements serve as primary data required for calibration,
validation, and testing of groundwater models, and it is often not until development of these models that
the limitations of existing water-level data are fully recognized. Furthermore, enhanced understanding of
the groundwater-flow system and data limitations identified by calibrating groundwater models provide
insights into the most critical needs for collection of future water-level data.
Long-term water-level data are applicable to a wide range of water resource issues. These include the
effects of groundwater withdrawals and other hydrologic stresses on groundwater availability such as:
land subsidence, changes in groundwater quality, and surface-water and groundwater interaction.
4.3
Groundwater Quality Monitoring
Whether the goal of the monitoring effort is inventory or detection of specific contamination, the
information gathered during sampling efforts must be of known standard and well documented. Highquality chemical data collection is essential in many groundwater monitoring programs. Each monitoring
program, however, has unique needs and goals that are fundamentally different from surface-water
investigative activities. The reliable detection and assessment of subsurface contamination require
minimal disturbance of geochemical and hydrogeologic conditions during sampling. The technical
difficulties involved in collecting truly "representative" samples are well documented (Grisak et al. 1978,
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Wood 1981). For further information on groundwater sampling methods, see the Forest Service Technical
Note “Groundwater Sampling.”
4.3.1
Selection of Groundwater Quality Monitoring Sites and Parameters
Decisions about the placement and construction of monitoring wells are among the most difficult in
developing an effective monitoring program (Barcelona et al. 1985). The initial locations and depths of
new monitoring wells should be selected on the basis of the best available pre-drilling data. Then as the
actual installation of these wells progresses, new geologic and hydrologic data should be incorporated into
the overall monitoring plan to ensure that the finished wells will perform the tasks for which they are
designed. In most instances, it is advisable to select a minimum array of monitoring wells for the
collection of geologic and hydrologic data. Then additional wells can be designed and constructed to more
effectively meet the goals of the monitoring program.
Parameter selection for water quality monitoring is very important to the effective planning of sampling
and analytical protocols (Barcelona et al. 1985). For exploratory efforts, and for little added expense, it is
useful to obtain slightly more chemical and hydrologic data than those required by the immediate
information needs of the program. The added data can normally be put to good use as the site conditions
become better defined. For example, in a situation where essentially no water quality data exist for a site,
a complete mineral analysis of the aquifer materials and site soils could be included. The mineralogical
results provide an internal consistency check on major ionic constituents, field determinations (e.g.,
alkalinity) and the potential effects of unusually high levels of metals or nutrients. Reliable analytical
methods for ionic constituents and routine field determinations (pH, Eh, temperature, conductance and
alkalinity) for groundwater samples are well referenced by the U.S. EPA, State agencies, and various other
groups (e.g., ASTM, National Sanitation Foundation). The results of the complete mineral analysis and
field determinations define the major ion solution chemistry, which is quite valuable to obtaining an
overall picture of the subsurface system of interest. Chemical speciation of many specific inorganic
constituents of interest (e.g., Fe, Cu, Pb) may be controlled by the inorganic solution chemistry. In turn,
the speciation of the chemical constituents of interest affects subsurface transport behavior. With a
complete mineral analysis and a clear view of information needs, one can then select the additional
chemical parameters of interest. These parameters may be characterized as general groundwater quality
parameters and pollution indicator parameters.
Water Quality Indicators
One of the key elements in the design of a water quality monitoring program is the selection of the
properties, elements, and compounds (indicators) to be measured, whether the program is focused on
background conditions, land use impacts, or compliance monitoring. Selection of indicators for
monitoring programs should be based on their relevance to important water quality issues, such as human
or aquatic health protection, and the existence of appropriate and well-established analytical
methodologies.
Because of differences in the importance of water quality issues in various regions of the country and
because of the potential for significant differences in the objectives of monitoring programs, no one set of
indicators is suitable or appropriate for all monitoring programs. Indicators appropriate for groundwater
quality monitoring should meet two general criteria. First, a parameter should be a candidate for
monitoring because it fulfills one or more of the following:
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




Is potentially toxic to human health and the environment, livestock, and plants; for example,
pesticides, volatile-organic contaminants, trace elements, nitrate and phosphorus.
Impairs the suitability of the water for general use; for example, hardness, iron, manganese, taste,
odor, and color.
Is of interest in surface water and may be transported from ground- to surface-water systems; for
example, nutrients such as ammonia, nitrite, and nitrate.
Is an important "support variable" for interpreting the results of physical and chemical
measurements; for example, temperature, specific conductance, pH, major ion balance, depth to
the water table, and selected isotopes.
Is an indicator of a condition or contaminant of concern with one or more of the characteristics
described above.
Second, analysis of the candidate indicator should be affordable by using well-established analytical
methods at appropriate minimum-detection and reporting levels necessary to achieve the objectives of
study. It is not always necessary or even affordable to monitor for every potential contaminant of
concern. It may be sufficient for a particular study to select a set of parameters that will indicate
conditions requiring more intensive investigation. For example, oil field waste fluids may contain a wide
variety of potential contaminants, but detecting a release of these fluids generally will only require
monitoring for a smaller set of parameters.
Based on these criteria, the following general groups of indicators should be considered for groundwatermonitoring programs, depending on the program objectives.










Field measurements (temperature, specific conductance, pH, Eh, dissolved oxygen, alkalinity,
turbidity, salinity, depth to water)
Major inorganic ions and dissolved nutrients (i.e., TDS, Cl, N03, SO4, PO4, SiO2, Na, K, Ca, Mg, NH4)
Organic carbon
Pesticides
Volatile and semi-volatile organic chemicals
Methane
Metals and trace elements (i.e., Fe (total, ferrous, and/or ferric), Mn, Zn, Cd, Cu, Pb, Cr, Ni, Ag, Hg,
As, Sb, Se, Be, B)
Bacteria and viruses (DNA fingerprinting)
Radionuclides
Environmental isotopes (H, O, S, N)
The process for selecting specific indicators for groundwater monitoring is discussed below.

Analyze Existing Information: The first step in the process is to determine whether there is a
recently documented occurrence of the indicator(s) by consulting existing information. This
includes identifying the sufficiency and usability of those data as well as identifying any data gaps
that may need to be addressed. In many areas, a large amount of water quality data has been
collected by many organizations to address a wide range of objectives. Many of these data can be
obtained from the U.S. Environmental Protection Agency's STOrage and RETrieval (STORET), the
U.S. Geological Survey's (USGS) National Water Information System (NWIS), and state databases.
In addition, data may be available from the USDA Agricultural Service and Forest Service long-term
experimental watersheds.
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
Determine Whether the Constituent or Contaminant Is Likely to Occur in the Groundwater System:
This step assesses the likely presence of specific indicators that have no documented occurrence
and have not been previously analyzed for in samples collected from the aquifer system of
interest. This assessment should take into account what is known about the potential sources of
the contaminants of interest, the physical and chemical properties of the contaminants, and
knowledge of the local hydrogeology and susceptibility of the aquifer to contamination, as well as
what has been reported in groundwater in areas with similar conditions and activities. Detailed
lists of indicators that could be considered for monitoring in areas with different types of land use
and sources of contaminants can be found in Franke (1997).

Test and Validate Constituent Occurrence: A screening survey begins with selecting wells in the
aquifer system to be sampled to determine if the constituent of interest is present. The number
of wells to be assessed would be determined on the basis of the size of the study region and the
complexity of the hydrogeologic setting. The timing of the survey might have to be considered
because the presence of some constituents may vary from non-detectable to above acceptable
levels on a temporal or seasonal basis within the same well due to variations in flow within the
aquifer, local land usage, or with well usage. On the basis of the results of this survey, the
investigator would determine whether the constituent should be included for subsequent
sampling of the system. As knowledge of the occurrence of different constituents in different
environmental settings improves, the uncertainty associated with understanding of indicator
occurrence, as well as the need for extensive verification, should decrease.
4.3.2
Frequency of Groundwater Quality Sampling
Traditional determinations of optimum frequencies for groundwater sampling have been made by
regulation or from statistics (Barcelona et al. 1985). Sampling frequencies determined by these methods
emphasize data needs and the cost of sample collection and analysis. A more reasoned approach is first to
evaluate the objectives of the monitoring and type of contaminant source being monitored (if any): a spill,
slug, intermittent source, or continuous source. Then one should consider the likely nature of any
contaminant plumes to be monitored, determine the minimum desired sampling spacing in terms of
length along the groundwater flow path, and use available hydrologic data to calculate the required
frequency to satisfy these goals.
4.3.3
Techniques and Protocols for Groundwater Quality Sampling
Water quality monitoring and analysis for Forest Service-related groundwater studies should conform to
techniques and protocols established by the U.S. Geological Survey in the National Field Manual for the
Collection of Water-Quality Data, Techniques of Water-Resources Investigations Book 9 (referred to in this
technical guide as the “USGS National Field Manual”; http://water.usgs.gov/owq/FieldManual/), unless
there are other governing regulatory requirements or specific Forest Service policy or guidance. The USGS
National Field Manual describes protocols and provides guidelines for USGS personnel who collect data to
assess the quality of the Nation’s surface-water and groundwater resources. Each chapter of the USGS
National Field Manual is published separately and revised periodically. New chapters and revisions can be
found online at the Internet address above. See the Forest Service Groundwater Technical Note on
Groundwater Sampling for agency guidance on the collection of groundwater samples that synthesizes
information in the USGS National Field Manual.
The USGS National Field Manual is targeted specifically toward field personnel to:
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



Establish and communicate scientifically sound methods and procedures;
Provide methods that minimize data bias and, when properly applied, result in data that are
reproducible within acceptable limits of variability;
Encourage consistent use of field methods for the purpose of producing nationally comparable
data; and
Provide citable documentation for USGS water-quality data collection protocols.
Formal training and field experience are needed to implement the protocols described in this manual
correctly. Sampling protocols addressed in the USGS National Field Manual include the following:

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






Preparations for Water Sampling
Selection of Equipment for Water Sampling
Cleaning of Equipment for Water Sampling
Collection of Water Samples
Processing of Water Samples
Field Measurements
o Temperature
o Dissolved Oxygen
o Specific Electrical Conductance
o pH
o Reduction-Oxidation Potential-Electrode Method
o Alkalinity and Acid Neutralizing Capacity
o Turbidity
Biological Indicators
o Five-day Biochemical Oxygen Demand
o Fecal Indicator Bacteria
o Fecal Indicator Viruses
o Protozoan Pathogens
Bottom-Material Samples
Safety in Field Activities
Monitoring for Legal and Regulatory Situations
Water quality monitoring for regulatory purposes, particularly at contaminated sites, may require specific
techniques and protocols identified by the lead Federal or State agency. Because these potential
requirements and guidelines are too varied to summarize here, consult the applicable regulatory agency
for its specific water quality monitoring requirements and guidance.
Water quality sampling for contaminant investigation and remediation, for regulatory compliance, or
potentially related to litigation, should be performed by people professionally qualified to do this type of
work and water quality analyses should be performed at an EPA certified laboratory.
4.3.4
Sources of Sampling Error
Representative (i.e., artifact or error free) sampling is a function of the degree of detail needed to
characterize subsurface hydrologic and geochemical conditions and the care taken to minimize
disturbance of these conditions in the process (U.S. EPA 1993). To collect high quality water quality data,
investigators must identify the type and magnitude of errors that may arise in groundwater sampling.
Table 4‒2 presents a list of the general steps involved in sampling and their principal sources of error.
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Table 4.2—Generalized steps involved in sampling and the principal sources of error.
Sampling Activity
Sources of Error
Establishing a Sampling Point
Improper construction/placement/development/maintenance
Field Measurements
Instrument malfunction; operator error; field conditions; vandalism
Sample Collection
Cross-contamination; sample exposure; degassing; oxygenation
Field blanks, Standards
Operator error; matrix interferences
Preservation/storage
Matrix interference; handling; labeling errors; wrong preservative
Transportation
Delay beyond holding times; sample loss
Other factors affecting groundwater quality sampling errors are the contamination of the subsurface by
drilling fluids, grouts, or sealing materials; the sorptive or leaching effects on water samples due to well
casing; pump or sampling tubing materials' exposures; and the effects on the solution chemistry due to
oxygenation, depressurization, or gas exchange caused by the sampling mechanism. Two of the most
critical elements of a monitoring program are establishing both reliable sampling points and simple,
efficient sampling protocols that will yield data of known quality.
Gillham et al. (1983) published a useful reference on the principal sources of bias and imprecision in
groundwater monitoring results. Their treatment is extensive and stresses the minimization of random
error, which can enter into well construction, sample collection, and sample handling operations. Gillham
et al. further stressed the importance of collecting precise data over time to maximize the effectiveness of
trend analysis, particularly for regulatory purposes. Accuracy also is important because the ultimate
reliability of statistical comparisons of results from different wells (e.g., upgradient versus downgradient
samples) may depend on differences between mean values for selected constituents from relatively small
replicate sample sets. Therefore, systematic error must be controlled by selecting proven methods for
establishing sampling points and collecting samples to ensure known levels of accuracy.
4.3.5
Quality Assurance and Quality Control Plans
Quality Assurance and Quality Control (QA/QC) is a large and complex discipline with its own specialists.
Larger or complex projects often have a dedicated QA/QC person with specialized training and experience.
Smaller or less complex projects may be completed by non-specialists following standard QA/QC
procedures (i.e., U.S. EPA, other Federal, State, or industry). Not all studies or monitoring efforts require
the level of QA/QC described here, for example, screening water quality at springs or other groundwaterdependent ecosystems.
Following is only a brief summary of some of the key elements of QA/QC. The level of QA/QC has to be
matched with the scope and objectives of the project. This is done through a QA/QC plan. A QA/QC plan
includes the establishment of a sampling procedure designed to minimize sources of error in each stage of
the sampling process, from sample collection to analysis to reporting of analytical data. Key elements
include:
1. Development of a statistically sound sampling plan for spatial and temporal characterization of
groundwater (U.S. EPA 1989);
2. Installation of a vertical and horizontal sampling network, which allows collection of samples that
are representative of the subsurface;
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3. Use of sampling devices that minimize disturbance of the chemistry of the formation water;
4. Use of decontamination procedures for all sampling equipment to minimize cross-contamination
between sampling points (ASTM 1990);
5. Collection of QA/QC samples (field blanks, duplicates, etc.); and
6. Bottling, preservation, and transport of samples to maximize the integrity of the samples.
Additional QA/QC procedures must be followed in the laboratory for valid results. As requirements for
precision and accuracy increase, the type and number of QA/QC samples will increase.
Quality assurance and quality control measures are those activities undertaken to demonstrate the
accuracy (how close to the real result) and precision (how reproducible the results are) of monitoring.
Quality Assurance (QA) generally refers to a broad plan for maintaining quality in all aspects of a program.
This plan should describe how the monitoring effort will be undertaken: proper documentation of all
procedures, training, study design, data management and analysis, and specific quality control measures.
Quality Control (QC) consists of the detailed steps taken to determine the validity of specific sampling and
analytical procedures. Quality assessment is the evaluation of the overall precision and accuracy of the
data, after the analyses have been run.
Internal checks that are performed by the project field staff and project laboratory include:
Field and Trip Blanks: A trip blank is deionized water treated as a sample, generally either shipped
with the sample bottles from the laboratory or collected in the office prior to departure. It is used to
identify errors or contamination in sample collection, transport, and analysis for volatile organic
compounds. Because trip blanks can absorb volatile organic contaminants in the ambient
environment before they reach the field site, it is important that they are stored, transported, and
handled to avoid exposure to potential volatile organic vapor sources such as petroleum fuels, vehicle
exhaust, or painting materials. The key to a trip blank is that it went everywhere that the bottles went
for the duration of the sampling event and is treated just like a sample at the end of the event.
Discard trip blanks if they are not used with the shipment of sample containers with which they
arrived. A field blank is deionized water collected in the field, usually once or twice each day, by using
the same water used to wash and decontaminate field gear in between samples. Once collected, each
field blank is treated just like a sample upon collection. With the use of trip blanks, field blanks
primarily verify the integrity of the field rinse water.
Negative and Positive Plates (for bacteria): A negative plate results when the buffered rinse water (the
water used to rinse down the sides of the filter funnel during filtration) has been filtered the same way
as a sample. This is different from a field blank in that it contains reagents used in the rinse water.
There should be no bacteria growth on the filter after incubation. It is used to detect laboratory
bacterial contamination of the sample. Positive plates result when water known to contain bacteria
(such as wastewater treatment plant influent) is filtered the same way as a sample. There should be
plenty of bacteria growth on the filter after incubation. It is used to detect procedural errors or the
presence of contaminants in the laboratory analysis that might inhibit bacteria growth.
Field Duplicate: A field duplicate is a duplicate sample collected by the same team or by another
sampler or team at the same place and same time. It is used to estimate sampling and laboratory
analysis precision. It can be submitted to the laboratory as a either a specified duplicate or a blind
field duplicate by giving it a sample identification unrelated to that of the original sample so that the
laboratory does not know which sample it is supposed to replicate. All field-based sampling plans
should include submission of a subset of duplicate samples (at least 10 percent of all field analyzed
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samples) for laboratory analyses to confirm the field results and provide information on how the field
results correlate with laboratory results.
Equipment Rinsate Samples: An equipment rinsate sample is collected in the field following
decontamination of sampling equipment, by passing deionized water through the equipment
following the same procedures used to collect a regular sample. It is used to verify the effectiveness
of equipment decontamination procedures.
Laboratory Replicates: A laboratory replicate is a sample that is split into subsamples at the laboratory.
Each subsample is analyzed and the results compared. They are used to test the precision of the
laboratory measurements. For bacteria, they are used to obtain an optimal number of bacteria
colonies for counting purposes.
Spike Samples (also referred to as Matrix Spike and Matrix Spike Duplicates): A known concentration
of the indicator being measured is added to the sample. This should increase the concentration in the
sample by a predictable amount. It is used to test the accuracy of the method of analysis.
Calibration Blank: A calibration blank is deionized water processed like the samples and is used to
"zero" the instrument. It is the first "sample" analyzed and used to set the meter to zero. This is
different from the trip blank in that it is "sampled" in the laboratory. It is used to check the measuring
instrument periodically for "drift" (the instrument should always read zero when this blank is
measured). It can also be compared to the trip blank to pinpoint where contamination might have
occurred.
Calibration Standards: Calibration standards are used to calibrate a meter. They consist of one or
more standard concentrations (made up in the laboratory to specified concentrations) of the indicator
being measured, one of which is the calibration blank. Calibration standards can be used to calibrate
the meter before running the test, or they can be used to convert the units read on the meter to the
reporting units (e.g., absorbance to milligrams per liter).
Field staff and a quality control laboratory perform external checks. The results are compared with those
obtained by the project laboratory. U.S. EPA and many States operate laboratory quality control
certification programs and require that all regulatory samples be analyzed by approved laboratories. All
Forest Service water quality samples that may be used in regulatory or legal proceedings should be
analyzed by laboratories certified under one or more of these programs.
Split Samples: A split sample is a sample that is divided into two subsamples at the laboratory. One
subsample is analyzed at the project laboratory and the other is analyzed at an independent
laboratory. The results are compared.
Outside Laboratory Analysis of Duplicate Samples: Either internal or external field duplicates can be
analyzed at an independent laboratory. The results should be comparable with those obtained by the
project laboratory.
Knowns: The quality control laboratory sends samples for selected indicators, labeled with the
concentrations, to the project laboratory for analysis prior to the first sample run. These samples are
analyzed and the results compared with the known concentrations. Problems are reported to the
quality control laboratory.
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Unknowns: The quality control laboratory sends samples to the project laboratory for analysis for
selected indicators, prior to the first sample run. The concentrations of these samples are unknown to
the project laboratory. These samples are analyzed and the results reported to the quality control
laboratory. Discrepancies are reported to the project laboratory.
Not only is it important to have a properly developed QA/QC plan, but other project documentation
should demonstrate how actual sampling related activities adhered to the plan. This includes thorough
field documentation such as logbooks, standardized field forms, and sample chains-of-custody as
described further below.
4.4
Evaluation and Reporting
Data collected as part of a monitoring network should be archived in a database, in accordance with
Forest Service policy so that they are readily accessible to specialists, decision makers, and researchers
(see FSM Chapters 1920 and 1940 for policy on archiving monitoring data). The database should be a
designated enterprise data management system, but for data that do not currently have an enterprise
system available it could be a simple Excel spreadsheet stored as part of a digital project archive. The
Advisory Committee on Water Information (ACWI 2009) has proposed standards for documenting
groundwater data for a National Ground Water Monitoring Network.
4.4.1
Water Quality Data Reporting
Thorough and accurate field notes can mean the difference between usable and unusable data. All field
notes obtained for network sites should be neat, legible, and leave no doubt about interpretation. Field
notes should include the following information for the purposes of thorough documentation, and if
necessary, to help identify causes of questionable data or resolve disputes:














Date, time, location, and purpose of sampling;
Names and affiliations of all field personnel including contractors;
Weather conditions;
Dates, times, and results of field equipment calibration;
Sample location measurements – ideally sufficient to relocate the original spot;
Any conditions of a sample location that might affect the sample (photos, sketches if necessary);
Starting time for collection of each sample;
Name, initials, or other identifier of sample collector of each sample;
Identifiers of all samples exactly as written on the sample containers, including QA/QC samples
(including actual and dummy name for laboratory blind samples);
All field readings, recorded exactly as read without conversions (can be done later);
Notes on related instrument/logger/unit malfunctioning, or site disturbances if any;
Deviations from plans, procedures, or protocols and reasons for deviations;
Any information related to the project exchanged in the field with third parties that are not part of
the field effort; and
Any other information that may be potentially relevant to someone interpreting the data.
Errors or modifications should be indicated by a single line drawn through them (no erasures or blackouts)
and initialed by the person making the change. Field notes should be initialed or signed on each page by
the person taking them. They should be photocopied or scanned as soon as practicable and uploaded to
the applicable database or electronically filed with the data in the event the original notes are lost or
damaged. Copies of field notes are kept with project records.
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Any electronic files used for the data collection (such as graphs or spreadsheets of field parameters during
well purging) should be backed up and archived in the appropriate database. Hard copies should be kept
with project records. Well-construction data for each well used in the network should be archived
accompanied by a sketch of the well.
Any deviations from established test-analysis procedures or assumptions should be documented and kept
with project records. If required, chain-of-custody documents for samples should be kept in accordance
with ASTM guidelines (ASTM 2010) or applicable regulations.
The need to collect other types of hydrologic data, in addition to groundwater levels or water quality data,
as part of an observation network is often overlooked (Taylor and Alley 2001). Meteorological data aids in
the interpretation of water-level changes in observation wells; therefore, include rain gauges as part of a
network if there are no representative gauges in the vicinity. Where observation wells are located in
aquifers that have a strong hydraulic connection to a stream or lake, hydrologic data (stream discharge or
stage) are useful in examining the interaction between groundwater and surface water. In addition,
water-use data, such as pumping rates and volumes of pumped water can greatly enhance the
interpretation of trends observed in water levels.
Contaminant detection is generally the most important aspect of a water quality monitoring program, and
must be assured in network design. False-negative contaminant readings due to the loss of chemical
constituents or the introduction of interfering substances that mask the presence of the contaminants in
water samples can be very serious. Such errors may delay needed remedial action and expose either the
public or the environment to an unreasonably high risk. False-positive observations of contaminants may
call for costly remedial actions or more intensive study, which are not warranted by the actual situation.
Thus, reliable sample collection and data interpretation procedures are central to an optimized network
design.
If field work is being performed by a contractor, it is a good idea to request or require in the project scope
of work that a scanned copy of all field documentation compiled by the contractor be provided to the
Forest Service.
4.4.2
Water-Level Data Reporting
Water-level data reporting techniques vary greatly depending on the nature of the data and their
intended use, but too often water-level measurements are simply tabulated and recorded in a paper file
or electronic database. Simple tabulation is useful for the determination of average, maximum, and
minimum water levels but does not easily reveal changes or trends caused by seasonal and annual
differences in precipitation, water use, or other hydrologic stresses. The Forest Service Groundwater
Technical Note on Groundwater Level Measurements contains some additional information on managing
water-level data, including time-series data collected by data loggers.
Water-level Hydrographs
Water-level hydrographs are graphical representations showing changes in water levels over time and are
a particularly useful form of data reporting. They provide a visual depiction of the range in water-level
fluctuations, seasonal water-level variations, and the cumulative effects of short-term and long-term
hydrologic stresses. In general, the value and reliability of the information presented by a water-level
hydrograph improves with increasing frequency of measurement and period of hydrologic record.
Hydrographs that are constructed from infrequent water-level measurements, or that have significant
gaps in time between the measurements, generally are difficult to interpret and may lead to biased or
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mistaken interpretations about the frequency and magnitude of water-level fluctuations and their causes.
Depending on the frequency of water-level measurement and period of hydrologic record, water-level
hydrographs can be constructed to illustrate historical water levels, compare recent and historical waterlevel data, and present descriptive statistics for water-level measurements.
Figure 4–3 shows hydrographs for a well in Vanderburgh County, Indiana, illustrating (A) continuous
record of daily water-level measurements made over about a decade, (B) comparison between water-level
measurements made in a single year to historical high and low water-level measurements, and (C)
statistical distribution (boxplots) of water levels for each month (Taylor and Alley 2001).
Figure 4–3—Hydrographs for a well in Vanderburgh County, Indiana (Taylor and Alley 2001).
To produce a hydrograph that truly reflects changes in water levels, the data may require processing or
data reduction to remove the effects of barometric pressure, aquifer conditions, and well conditions. This
processing may be particularly complex and require specialized expertise.
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The accessibility of water-level data is greatly enhanced by the use of electronic databases, especially
those that incorporate Geographic Information System (GIS) technology to depict the locations of
observation wells and staff gauges relative to pertinent geographic, geologic, or hydrologic features. The
availability of electronic information transfer on the Internet greatly enhances the rapid retrieval and
transmittal of water-level data to potential users. Water-level hydrographs, maps of observation-well and
staff-gauge networks, tabulated water-level measurements, and other pertinent information all can be
configured for access on the Internet. A significant advantage of this method of data reporting is the ease
and speed with which groundwater-level data can be updated and made available to users.
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References
Advisory Committee on Water Information (ACWI). 2009. A national framework for ground-water
monitoring in the United States. Advisory Committee on Water Information, Subcommittee on
Groundwater. 78 p. http://acwi.gov/sogw/pubs/tr/sogw_tr1_Framework_june_2009_Final.doc.
American Society for Testing and Materials (ASTM). 1990. Standard practice for decontamination of field
equipment used at nonradioactive waste sites. Standard D5088-02. West Conshohocken, PA: American
Society for Testing and Materials.
American Society for Testing and Materials (ASTM). 1996. Standard guide for design of groundwater
monitoring systems in karst and fractured-rock aquifers. Standard D5717-95e1. West Conshohocken, PA:
American Society for Testing and Materials. http://www.astm.org/Standards/D5717.htm.
American Society for Testing and Materials (ASTM). 2010. Standard guide for sampling chain-of-custody
procedures. ASTM D4840-99(2010). 8 p. http://www.astm.org/Standards/D4840.htm.
Barcelona, M.J.; Gibb, J.P.; Miller, R.A. [et al.]. 1983. A guide to the selection of materials for monitoring
well construction and groundwater sampling. Illinois State Water Survey Contract Report 327. USEPARSKERL, EPA-600/52-84/024. Washington, DC: U.S. Environmental Protection Agency. 78 p.
Barcelona, M.J.; Gibb, J.P.; Helfrich, J.A.; Garske, E.E. [et al.]. 1985. Practical guide for groundwater
sampling. Illinois State Water Survey Contract Report 374. USEPA-RSKERL under cooperative agreement
CR-809966-01. Las Vegas, NV: U.S. Environmental Protection Agency, Environmental Monitoring and
Support Laboratory. 94 p.
Brobst, R.B. 1984. Effects of two selected drilling fluids on groundwater sample chemistry. In: Monitoring
wells: their place in the water well industry. National Well Water Association Meeting and Exposition.
Educational Session. Las Vegas, NV: National Well Water Association.
Driscoll, F.G. 1986. Groundwater and wells. St. Paul, MN: Johnson Division. 1089 p.
Evans, R.B.; Schweitzer, G.E. 1984. Assessing hazardous waste problems. Environmental Science and
Technology. 18(11): 330A–339A.
Florida Department of Environmental Protection. 2008. Guidance for groundwater monitoring plan design.
Florida Department Environmental Protection, Bureau of Water Facilities Regulation. 28 p.
http://www.dep.state.fl.us/water/groundwater/docs/groundwater-monitoring-plan-design_final.pdf.
Fonseca, J. 2008. Aquifer monitoring for groundwater-dependent ecosystems. Pima County, AZ: Pima
County Office of Conservation Science. 36 p.
http://www.pima.gov/cmo/sdcp/reports/d51/Aquifer%20Report%20042808.pdf
Fetter, C.W. 1999. Contaminant hydrogeology. 2nd ed. Upper Saddle River, NJ: Prentice Hall. 500 p.
Franke, O.L. 1997. Conceptual frameworks for groundwater quality monitoring. Denver, CO:
Intergovernmental Task Force on Monitoring Water Quality. 112 p.
http://water.usgs.gov/wicp/gwfocus.pdf.
Gorelick, S.M.; Evans, B.; Remson, I. [et al.]. 1983. Identifying sources of groundwater pollution: an
optimization approach. Water Resources Research. 19(3): 779–780.
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Grisak, G.E., Jackson, R.E.; Pickens, J.F. [et al.]. 1978. Monitoring groundwater quality: the technical
difficulties. Water Resources Bulletin. June.
Gillham, R.W.; Robin, M.J.L.; Barker, J.F.; Cherry, J.A. [et al.]. 1983. Groundwater monitoring and sample
bias. Prepared for American Petroleum Institute, American Petroleum Institute Publication 4367.
Washington, DC. 206 p.
Heath, R.C. 1976. Design of groundwater level observation-well programs: Groundwater. 14(2): 71–77.
Lapham, W.W.; Wilde, F.D.; Franceska, D.; Koterba, M.T. [et al.]. 1997. Guidelines and standard
procedures for studies of groundwater quality: selection and installation of wells and supporting
documentation. Water-Resources Investigations Report 96-4233. Washington, DC: U.S. Department of
Interior, U.S. Geological Survey. 110 p. http://water.usgs.gov/owq/pubs/wri/wri964233/.
Peters, H.J. 1972. Criteria for groundwater level data networks for hydrologic and modeling purposes.
Water Resources Research. 8(1): 194–200.
Quinlan, J.F. 1989. Ground-water monitoring in karst terranes: recommended protocols and implicit
assumptions. Report EPA/600/X-89/050. Las Vegas, NV: U.S. Environmental Protection Agency,
Environmental Monitoring Systems Laboratory. 100 p.
Taylor, C.J.; Alley, W.M. 2001. Groundwater-level monitoring and the importance of long-term water-level
data. U.S. Geological Survey Circular 1217. 68 p. http://pubs.usgs.gov/circ/circ1217/.
Triad Resource Center. 2012. http://www.triadcentral.org/.
U.S. Environmental Protection Agency (EPA). 1989. Report on minimum criteria to ensure data quality.
Report EPA 530/SW-90/021. Washington, DC: U.S. Environmental Protection Agency. 36 p.
U.S. Environmental Protection Agency (EPA). 1993. Subsurface characterization and monitoring
techniques. Report EPA 625/R-93/003. Cincinnati, OH: U.S. Environmental Protection Agency Center for
Environmental Research Information.
U.S. Environmental Protection Agency (EPA). 2012. Quality management tools - systematic planning.
http://www.epa.gov/quality/dqos.html. (13 December 2013).
U.S. Geological Survey (USGS). variously dated. Chapters A1-A9: National field manual for the collection of
water-quality data. In: Techniques of water resources investigations, Book 9.
http://pubs.water.usgs.gov/twri9A.
Wehrmann, H.A. 1983. Monitoring well design and construction. Groundwater Age. 4: 35–38.
Winter, T.C. 1972. An approach to the design of statewide or regional groundwater information systems.
Water Resources Research. 8(1): 222–230.
Wood, W. W. 1981. Chapter D2: Guidelines for collection and field analysis of groundwater samples for
selected unstable constituents. In: Techniques of water resources investigation, Book 1. Washington, DC:
U.S. Geological Survey. 24 p.
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Additional References Related to Monitoring Groundwater and Groundwater Systems
Alley, W.M.; Reilly, T.E.; Franke, O.L. [et al.]. 1999. Sustainability of groundwater resources. U.S. Geological
Survey, Circular 1186. Denver, CO: U.S. Department of Interior, U.S. Geological Survey. 79 p.
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Appendix 4-A – Quality Assurance and Quality Control Guidelines for Field Data Collection
The following guidelines address common QA/QC procedures that are applied during field data collection
and are provided to give some sense of the minimum requirements for field data quality control, but are
not intended to provide a comprehensive review of data quality requirements. It cannot be
overemphasized that proper data quality control is critical to obtaining data that are considered reliable
and usable. Depending on the nature of the project data quality control may require developing formal
documents running to hundreds of pages, involve specialists in the area of data quality, require following
rigorous procedures, and require advanced statistical and other analyses techniques. These guidelines are
geared toward collection of water or soil samples when the data may be used for litigation purposes.
However, for projects involving litigation or regulatory compliance the use of a qualified contractor with
experience in collecting data for these purposes is recommended. For projects that are not likely to be
litigated, use of these guidelines is still encouraged.
Sample/Data Point Identification
Establish a systematic approach for identifying and labeling samples and data points before going into the
field. It should specify how the samples will be numbered (sequentially as collected or based on sample
location or some other way that best works for project purposes). Depending on the purposes of the
sample/data collection the sample/data point identification may also include one or more of the following
types of information:
1. Date and or time of sample/data collection.
2. An abbreviation indicating the location type (i.e., monitoring well (MW), piezometer (PZ)) or
sample type (i.e., groundwater (GW), surface water (SW)).
3. An abbreviation for the site name.
4. An abbreviation indicating who collected it (contractor, field crew).
5. Type of QA/QC the sample or data represents (i.e., duplicate (DUP), trip blank (TB), matrix
spike/matrix spike duplicate (MS/MSD)).
6. Other information that may be critical to later identifying samples or data.
Field Data Recording Procedures (General)
Field crew members should be aware that field records are potential legal records and must be properly
and consistently maintained. Be sure to write legibly. Language should be objective, clear, factual, and
free of personal feelings or other terminology that might prove inappropriate, since field records are the
basis for later written reports. All data should be recorded in indelible, waterproof ink (Sharpies or
something else resistant to smearing or running work best) and not pencil to avoid charges later of data
tampering. All errors should be crossed out with a single line so they are still readable. This helps with
trouble-shooting data problems, and reduces the potential for charges of data tampering. If the
information and data may be used in a legal context, corrections or changes to the records should be
initialed and dated. Ideally one person (preferably the field crew leader) should maintain the field log for
consistency.
At a minimum, daily field logs should begin with sample site location information, field crew member
names, weather conditions, and a summary of planned field activities or objectives. The top of each page
of the log should include a page number, an identifier for the site or project, and the date in case the field
log pages get separated. Signing or initialing the bottom of each page indicates who recorded the
information on the page.
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Daily field logs should be maintained chronologically so that field activities can be reconstructed. Even if
data are recorded elsewhere, the locations of all sample and data collection should be noted in the daily
field log along with the approximate time the activity was completed. All data recorded in the field by
hand should be recorded in the values and units in which they were measured to minimize recording
errors. Data can be converted later to a more useful format. Record all times in military time (i.e. 0800,
1430).
Critical, electronically recorded data (such as sample GPS coordinate locations) should be written down
while in the field to guard against possible electronic data loss. All calculations, results, and calibration
data for field sampling, field analytical, field screening, and field physical measurements should also be
recorded in the daily field logs, except where these are referenced as being recorded on approved field
forms. Any information with potential bearing on data quality should be noted, especially problems
encountered and how they were addressed.
Record information about photographs taken in the daily field log (photo number, time, direction, etc.) or
on a dedicated field photo information form. At the end of the day record the types, amounts, and
disposition of any field wastes generated during the day that require special handling and disposal. Taking
photographs of sample/data locations is a good practice for showing conditions at the time of
sample/data collection, or to help document location relative to other landmarks.
Additional Field Data Recording Procedures (Legal or Enforcement)
Some projects will have legal or enforcement implications making proper field data recording critical to
the outcome of a legal or enforcement action. Depending on the sensitivity of the work the following
additional field procedures should be employed.
The presence of all field visitors, whether expected or authorized, or not, should be noted in the daily field
log. Conversations that the field crew leader has with outside parties about the field activities or project
(other field crew members as a rule should not be talking about these things with outside people) should
be summarized in the field log book. This helps avoid potential he-said, she-said situations later. Unless
the field crew leader is authorized to talk with outside parties about specific topics related to the work, he
or she should refer outside inquiries to the appropriate person.
Blank lines or spaces in the daily field log should be lined through with a diagonal line to indicate that no
information was inserted. The person maintaining the field log should indicate the end of the log for that
day by signing it. All sample chain-of-custody forms should be completed at the end of the day, if not
completed during sampling.
Field Data Recording Media
The use of a field data recorder or preformatted field forms are useful for making sure all data are
collected and recorded as required. If a field data recorder or field forms are not available, a log of field
activities should be maintained. Frequently, the only way to troubleshoot data problems is by
reconstructing what happened in the field based on the field activity log. Furthermore, if the data is ever
challenged or questioned, this record may be the only means to defend its validity. While this can be kept
on special daily field log forms, it is preferable to keep it in some type of bound logbook or notebook
dedicated specifically to recording field information. Specially designed field logbooks with water resistant
paper are ideal. If a bound logbook is used, and not filled up, it is best reserved for recording future
information solely related to that project or site. If this is done, be sure all pages are numbered uniquely
and a table of contents is maintained identifying the starting page for each field event.
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Groundwater Inventory, Monitoring, and Assessment Technical Guide - DRAFT
Field Data Recorder software implements QA/QC through use of code sets and error checking. The
validation includes notice of incorrect codes and missing required values. The software also validates
measurement units (e.g., English or metric). There are very few free-form text fields other than
Comments and Notes. Additional validation occurs when data are uploaded from a PDR into NRM.
Field Record Handling
At the end of each day all hard copy field records not yet backed up should be photocopied or scanned
and stored in a safe place. This is especially important if the records are in a notebook or logbook that will
be used in the field again. Also backup all photographs and other electronic data and store the backups in
a safe place. Store the original and copy in separate locations per Forest Service record management
requirements. Lock up or otherwise secure all field records at the end of the day.
Field Risk Management
Most problems encountered in the field can be reasonably anticipated or preparations made to address
potential problems. Planning for how to deal with them will better ensure field time is used most
efficiently and productively. This is particularly important when fieldwork will be performed by someone
other than the project manager or person responsible for the direction and outcome of the project. By
developing specific approaches for how to respond to various problems within the context of the project
requirements, the field crew will be less likely to miss collecting important data or samples, or waste time
trying to fix an unimportant problem. Advance preparation and troubleshooting by the project manager is
particularly important when the field crew is working in remote or poorly accessible locations with limited
or no communication options. Things to consider include:
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Does the field crew have a properly prepared Job Hazard Analysis (FSH 6709.11 and 6709.12)
that covers allowable changes to field activities?
What are the sampling or data collection priorities? For example when is it essential to spend
time getting samples or data from specific locations, and when is it more important to
maximize the number of sample and data collection locations.
When might field activity have to be altered or halted in response to weather conditions? For
example, can water samples be collected in the rain?
When is it necessary to halt collecting certain types of samples or data in the event of
equipment or supply problems, and when should they proceed without the samples? For
example, if a field instrument malfunctions preventing collection of one or more types of field
data, can sample or other field data collection proceed without collection of that data?
How can field activities be acceptably re-sequenced?
What types of backup equipment or field supplies are essential if altering the planned
fieldwork or returning to the field at a later date or time is not an acceptable alternative?
If samples or data cannot be collected with the planned approach, what, if any alternative
approaches are acceptable?
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